Following hot on the heels of the VP180 (which was the first Axiom loudspeaker I had the pleasure to work on) we have been noticing the subject of a "VP160" popping up in the VP180 thread. There are a number a good reasons that such a centre channel might make sense for us to look into, number one being that it would be an 8 ohm load which is an important consideration for some receivers. And naturally we don't want to deny those that can't drive a VP180 the opportunity to own a big centre channel!
The problem from an engineering standpoint is the driver complement of the M60 that the VP160 would have to match. Simply popping the M60 drivers into a horizontal cabinet would result in an asymmetrical driver layout which is bad news for a centre channel. So, we'd like your thoughts on what you'd like to see in a VP160. The early discussions I have had with Ian on the subject are pointing towards an VP180 driver complement in an M60 sized cabinet with only one midrange in the middle. I look forward to hearing your ideas!

Andrew

The first thing that came to my mind after reading the title was to go with only one midrange in the center, to give you a WTMTW configuration following the similar pattern of the VP180. Maybe to compensate for only one midrange, could you go with a larger size midrange than a 5.25"?

I'm not very knowledgeable but is it possible to side port a centre channel? I wish the 180 was designed this way, if possible, because it wouldn't require it to be positioned away from the wall, it's deep enough on it's own.

Not sure it's the feedback you're looking for, but it's really all I can offer .

You know Cam, I think that came up on one of our counsel calls, and I think for a center channel you make a very valid point. It is actually a good thing to have an arc from your left/center/right front soundstage, Alan has even mentioned this. Having rear ports on the center does indeed make this difficult, I think having them on the sides would be a great idea, however, there might be some design reason why Axiom didn't take this path.

your quadpoles are very unique. following in the interesting desing of things, could you make work maybe.. one or two mids on the top. maybe giveing the center channel some vertical depth. maybe taper it upwards.

its most likely crazy and wouldn't work but just an idea. and it would be kinda cool. :0).. and how in the hell did you guys get the quads to work so well. they are amazing!! lol

only downside is you wouldn't be able to flip it around like the VP150

With the driver complement of the M60 an interesting prototype to compare with the WTMTW is a WTMW with the midrange and tweeter vertically arranged and ported of course like the M60.

M60 owners should be very stoked! This is an awesome concept.

I had assumed the new BigAss center was going to be just like that, sort of a W(T^M)W. I would have been really happy with one of those, although of course I expect to be even happier with my VP180 if I can pry it loose from Purolator's "we only work on weekdays" hands

The side ports seem like a great idea. They would be a problem in a conventional TV stand so you wouldn't want to put them on all the center models, but anything too big for a TV stand would be fantastic with side ports. Placement instructions normally suggest that the center should be a bit closer to the wall than the mains, in order to give a consistent distance to the listener, which implies the center needs to be real cozy with the wall.

Andrew, as Randy comments, the configuration that you describe would most closely follow the VP180 pattern, with tweeters(of course a second tweeter would have to be added)inside the woofers and mid-range(s)in the middle. It wouldn't appear to be necessary to use a larger mid-range, since the M60 of course uses the single 5 1/4" mid-range now.

In line with the comment by Dr. House, over the years I've mentioned several times the possibility of using a W T/M W configuration(possibly using the 4" mid-range from the QS4s). Although the same drivers(no additional tweeter)could be used, unfortunately there wouldn't appear to be enough space on the M60 enclosure for the 5 1/4" midrange and the tweeter to be positioned vertically, even if the tweeter surround was partially cut away to allow closer spacing.

I'm pretty much with JohnK on this - I really like the idea of a W T/M W configuration with the tweeter aligned above the midrange. To differentiate this new concept from the existing models, it might be good to experiment with this different form-factor. I know it is quite a departure from the narrow baffles we've come to know and love, and could consequently present some manufacturing challenges. Some people may appreciate a taller, squattier center rather than the impossibly long/low profile presented by the VP150 and VP180.

Until I saw that Andrew started this thread, I was sure it was going to be a thread where forum members espoused a concept that was ultimately not viable for Axiom. It's really great and surprising to see this kind of brainstorming on the forum.

I have been bugging Brent for a new center channel for a few years now....

I might wind up upgrading to the vp-180 still thinking about it.

if the new vp-160 would use 2 7" woofers with 1 5.25" mid and the standard aluminum tweeter. That would be MY ideal center....

i know this would require sourcing new speakers, it wouldn't be an "off the shelf" speaker..

If the intent for the proposed VP160 is to complement the M60 first and foremost, then I would think the combination of having the woofers to the outside and the tweeter and mid in the central position with the tweeter above the mid would likely be the best combo. As Tom implied, it will probably call for a slightly boxier cabinet with a wider baffle so I'm not sure if this would be desirable or not. The other alternative would be woofers to the outside with the tweet and mid mounted slightly diagonal to each other in the centre. Ideally, you might want a mid on each side of the tweeter but then it almost becomes a VP180 (with only 1 tweet difference). Several different combos to consider....

With WT^MW configuration the cabinet obviously will have to re-designed. However this will allow more choice when choosing a center speaker whether an individual wants a wider and slimmer centre (VP150/VP180) or a more "stocky" centre. This trade off in choice between the long/slim form factor and the short/tall of a possible VP160 will also allow greater placement given any room.

Not only does the WT^MW (ported) configuration use the exact same drivers as the M60 , I would imagine it would also have a good, smooth on and off-axis response as well come close to the sonic qualities, power handling and extension of the M60 tower that owners love.

Even at the extra added cost involved in designing a new cabinet, and the cost involved being more than a single M60 tower, I still believe this design will garner great interest from a lot of individuals - both current and future.

Personally, I think the 5 1/4" midrange is part of the Axiom magic. I'm not nearly as fond of the 4" midrange in the QS4s, although mine are probably tis, not v2s, and certainly not of the current lineup. Of course, when I mentioned this to Ian, he kind of laughed and said it was more about the crossovers and matching the drivers to them than in the drivers themselves.

I think to match the M60s, you need the same size drivers, though.

Either way with the 4" or 5 and 1/4" inch drivers as the midrange you would need to design a new cabinet with the WT^MW config. Since the concept is a M60 centre, the single 5 and 1/4" midrange would make the most sense.

With using a smaller driver like the 4" there a certain physics that you can't overcome though. One thing to note as well as providing a linear response, excellent on and off-axis performance with special emphasis on the speech discrimination band (which as human beings we are most critical to). You also want to include in the design as close to the power handling and bottom end extension of the M60 as well.

For those of us that have built our cabinets for the width of a vp150, it would be nice if the 160 was the same width of a 150 but just taller. Also if its a ported design front ports would be nice so we didn't need to worry about rear clearance.

Yet there will be people who can go wider, but not taller.

Mostly junk food, I think.

Personally I think the perfect match for M60s is a VP180, but that's just me...

Yea that's the vp155

Could a M40 or M50 sized cabinet do?

Mindless question as my only claim to fame was installing RadioShack drivers in oak barrels and using them for end tables, ...well that; and numerous colour organs. Just shows how bizarre the 70s were.

Andrew, several suggestions for changes of varying degrees of complexity have been made. The simplest change to eliminate the 4 ohm "problem" would be to introduce the VP180-6 and M80-6, involving no changes whatever, but rating the speakers at a 6 ohm nominal impedance, rather than the 4 ohm minimum impedance, in accord with typical practice in the industry. This would also have the substantial benefit of reducing the time and space wasted on the boards in discussing whether certain receivers would "work" with certain speakers.

If the M60 is to be modified, again the WTMTW configuration proposed would most nearly follow the VP180 pattern.

If the M60 enclosure(which would have to be modified in any case)could be increased about 1" in height(when horizontal), the 5 1/4" mid-range and the tweeter could apparently be placed in the desirable vertical orientation, especially if the tweeter mounting plate was partially cut away to allow for closer placement.

And to toss out something totally different, with the present sized M60 enclosure a triangular configuration in the middle, composed of the tweeter directly above two side-by-side 4" mid-ranges would be feasible and undoubtedly would astonish Axiom critics on certain other forums.

I have always liked the sound of the WT/MW designs I have heard and would like to see/hear one from Axiom.

I really dislike the look of the WT/MW designs, but that's just me.

Although not a "complete match" to the M60, this is an interesting concept JohnK. So is this the driver layout right here W(6.5") M(4") ^T(1")^ M(4") W(6.5"). What would you have in mind sealed or ported? One thing for sure this would be one cool looking design.

I’d just go W – M – T – M – W and call it a 6 ohm speaker. The cabinet would be about 4” longer than the M60 (or taller standing on end). Pretty much the same thing as the VP180, but with one, centered tweeter verses two tweeters. Some folks (actually a lot) do not like the idea of a center with more than one tweeter. I’d play around with the porting some too. Seeing how it’s a center, and placed horizontally, you could port it downward, or at the ends. I’d rather the ports be downward as I would not be able to see them and if the center was mounted above the screen, just flip it over and the ports would be up, and again, not visible. If the cabinet depth could be reduced a few inches by porting or some other form of CAD wizardry, it may be possible to mount the thing with two or three FMB’s (especially if the ports were on the bottom verses the back).

Edit: I keep forgetting that some folks need to lay the center on a shelf or on the top of a TV. Ports on the bottom wouldn't work too well for these situations. I wonder if ports could be on the ends and the bottom and simply plug the ports that would not be usable?

See, I think that's a problem. If Axiom is going to introduce a FOURTH center channel (not including the inwall/onwall stuff), it should be sufficiently different in form factor to warrant interest from people that don't find the other, existing options appealing.

If the impedance is the ONLY factor driving the issue, then Mike's scenario is a no-brainer. But I think that anybody with the money and real estate for a center that big is probably going to also be able to find a way to drive a 4-6 ohm speaker and can just get a VP180.



Right. Users should be able to wall-mount OR shelf-mount it easily and elegantly. Honestly, I don't think having ports on the back is a big issue at all.

Lots of existing and potential customers want to "step up" from the VP100, but the VP150 and VP180 may both have some fatal flaws for them (the misplaced perception that having two tweeters is "bad", the large size of both). I think Axiom can address ALL of these factors, but not by making yet another exceedingly long speaker. It should be something geared toward people that have narrower spaces to work with, either in the room or in their equipment racks. Not much wider than a VP100 but a bit taller to accommodate the larger woofers.

I think you make some excellent points tomtuttle. A different form factor should be considered here that is different from the VP150 and VP180. The VP100 has a nice small footprint but is limited to smaller/medium rooms so anyone with a seating position that is far away the VP100 is not ideal. Anyone looking to trade up for better performance or a bigger room and if there is a 4th centre (which is a lot of centres btw ) a cabinet that is not as long as the VP150 but with a trade off in added height would be ideal. I would think this would give an individual as much choice as possible when considering what centre option one wants.

I don't think there is a problem with rear porting either, dual front ports could be a consideration as well.

Would a variable port option be possible, where you would just remove a cover at the place you would want a port? Whether what was front, side, back, bottom, etc.

Just for clarity, I'm thinking of an Axiom treatment of something similar to this...

I just think that would be to bulky for my taste.

It looks like a mail box?

Randy, I like the way you phrased it. Because the VP150 is not to my taste, and the VP180 is just ridiculously large for some people.

I'm sure I could get used to it though.

Perhaps they could make the cabinet the same kind of height(width?) as the M60...BUT!...they could use a secondary baffle(over the cabinet baffle) to extend the centre height a little for the upper-centre mounted tweeter.

So...a reg cabinet, with a 3/4"(1/2"?) baffle added to the face, with a hump at the centre to mount the tweet. This will keep the overall package narrower, and the front baffle can extend out from any stands or HT cabinets, thereby clearing the "hump" if necessary(ie, if the shelf is narrow and won't clear the tweet).

[quote=tomtuttle]Just for clarity, I'm thinking of an Axiom treatment of something similar to this...[quote]

Yes tomtuttle. I think a design like that would look very nice with the classic tapered Axiom cabinet. JohnK was alluding to a similar design as well. Do you have any information about the dimensions of that speaker? Just curious to compare it to the size of the VP150.

When I first heard about the 180, I was initially excited and wanted one. But when I started to think about it, I just don’t have room for it and I most definitely do not have room for one under and one over my screen. Plus, I don’t want to hang one above my screen with chains, which I think it the only real option for the above screen location. There are those who feel two centers is a bad idea, but having done it, I’ll never go with one center again.

When Andrew posted this conceptual idea thread, I started thinking about it from a purely selfish perspective, and not a perspective from a builder / designer. I think that to make this possible, I need to put my cabinet maker hat back on and think about the cost / benefit ratios with differing cabinet sizes and shapes. When looking at it from that perspective, the “hump” or “triangle” ideas will be a show stopper. To do that would require a very radical cabinet change which will also affect veneering and internal bracing. It can be done, but I suspect the expense would be cost prohibitive. The strength of the cabinet is obtained by how it is assembled and the size of each cabinet piece. The cabinet structural integrity would be drastically reduced if the lid is cut to accommodate a hump or triangle. Cutting and assembling a lid with an odd shape would be a nightmare. To keep the cabinet structurally sound, but large enough to stack drivers vertically, it would obviously have to be squattier, like the one Tom posted the picture of. I personally do not like this look, but others do.

Whatever cabinet shape is determined, I would really like to see this thing wall mountable so that I could mount one above and one below my screen without stands or chains. That will require the cabinet depth be reduced, considerably, to get the pivot / weight moment point closer to the wall.

It sure would be fun to build a few of these differing design ideas and do some blind testing……

I’m also very pleased that Axiom has thrown this out for the general input of forum users. I’ve often mentioned during our CC meetings that a broader opinion base would be great for some of this stuff. Thank you for doing that Andrew.

Michael, for the record, the "hump" that I eluded to would be on the outer baffle...the cabinet would be standard Axiom style with flat angled sides, but with another, separate baffle with a CNC'ed hump in the middle attached. The second baffle is a separate piece, the same size as the standard baffle(which is folded and glued up like the standard cab's) but with the extra material in the middle to house the tweet above the midrange.

Perhaps an alternative would be to add a small appendage to house the tweeter on top of the cabinet, glued and screwed from inside the main cabinet. This could be done in black for all the cabinets, no matter what finish the customer chooses on the main cabinet. The "appendage" would only be the size of your fist, or thereabouts.

It may be possible for Axiom to manufacture their tweeter with a truncated or greatly reduced flange size, like this...



Which might make the standard cabinet width work. Dunno. I'll let you detail people figure it out. I'm just a concept guy.

I agree with Mike about trying to make it less deep than a standard M60. I disagree with him that he doesn't have room for a couple of VP180's, though

Edit: Doc, the speaker in the picture I linked is about 24"W x 11.25"H x 13.25"D. Those are 7" woofers and a 4" midrange.

If you want it to sound like an M60, though, you're going to need roughly the same cabinet volume as an M60.

Good point. You certainly couldn't expect the same bass extension.

But there's just not enough difference - to me - between a full-format VP160 and the VP180 to make it worth doing.

You're right that my thinking on this is back-asswards; trying to decide on the box and drivers FIRST is nuts. But, you know, Ian does perform miracles sometimes and Andrew brought it up. I'm just playing along.

If the box were sealed, it would be somewhat smaller than the ported M60 cabinets, no?

I know I've been shouted down a bit here, but I think that what Axiom really needs are surrounds to compliment the M80s and new VP180. Maybe called the QS80.

There are 3 types of floor standing mains, 3 types of centers now, but still only 2 types of surrounds. Surrounds that could go as low as at least 60Hz would be great. Maybe something as simple as replacing one of the mids with a woofer, and making the box a little bigger (or ported).

I know I'd buy them.

Still unlikely to sound the same.

Agreed Ken (and I don't want to thread jack this one any further), but surrounds that could go lower and match more closely would be nice.

sroode, the only reason i can think not to do what you are saying. Is, how much audio does the surrounds really see? Also what kind.. most of the movies i watch, its just random noise, not usually music, or voices (well sometimes, but not that often)... if the surrounds were used more often i could see it....

It's more than for movies, at least for me since I listen to music more than watching movies. Most people would have said the same thing about center channels, but in reality (or maybe just my opinion) you want all of your speakers to be closely matched and able to reproduce any frequency to truly duplicate reality.

Most people will not listen in 7 channel stereo mode for this reason alone. If what you say is true, the surrounds may just as well be cubes like Bose puts out. I've had them, and they suck.

Again, I'm thread jacking and being a little selfish, but just as I hoped that a center that could match the M80 would sound spectacular (and it more than did!) I know that surrounds that could reach lower would really complete the experience.

you are dead on with the center though. in movies 70% of the dialog comes from the center. so you do want a large center.. like i've said in other threads I've been asking if they were working on one for a year now... but never though to get them to make a custom one.... now i need to decide when/if i am going to get a new center... I REALLY want a wilson center... but i don't have 6k$ atm for a used center channel....

i wish, that they would use 7" woffers

I'd try the VP180 if I were you (not sure what your other speakers are). It's a fantastic center channel, and if you don't like it you can just pay the shipping to send it back. IMO, if you are looking in the $6k used price range, you can easily afford the $50 or so to "rent" the speaker for a month to see if it's what you want.

I think you will be more than happy with it.

Stevereeno:
I gotta agree with you on the surrounds. For SACD and DVD-A discs, the fuller-the-range the better! Of course, that applies to the center even more so!

A friend just bought a set of QS8's and i thought they would be bigger so yes a pair with 6 inch woofers would be nice .

I am loathe to reward Steve's threadjacking, but...

If you really want full-range surrounds, just get M80's for surrounds.

Done.

Thanks everyone for the excellent comments and discussion so far. Keep those ideas coming!
It's interesting that the VP160 discussion seems to be settling into two camps: Make it the same driver complement and cabinet dimensions as the M60 so that it matches closely in terms of bass/timbre or change the driver complement and/or the form factor into a taller, narrower cabinet to allow for smaller TV cabinets and possible wall mounting. It looks like I'll be busy with drawing up a few CAD designs and having prototypes built over the next few weeks! One thing to keep in mind is that our decision on what version to produce will be based on the outcome of our blind listening tests, even if the result is something that does not follow conventional "wisdom". That being said, we always try to take into account functional requirements and it's pretty clear that a centre channel with a smaller form factor than the VP180 might be very desirable. The porting arrangement is also something we will be taking a close look at and a sealed cabinet might be possible, the only downfall being a reduction in bass extension.

Andrew

Andrew, I don't feel I have anything worthwhile to add to the discussion but did want to mention, as others have, how great it is that you and Axiom in general are soliciting opinions here.

Sort of been done before by Infinity:

http://reviews.cnet.com/separate-speakers/infinity-il36c/1707-7869_7-6899676.html

The Infinity IL36c was my old center. It was good, but the VP150 was better. The VP180 even better.

Now wait a minute... the point has been explicitly made on here time and time again that there is no difference between a ported design and a sealed design, only in the enginering of the two designs. So why couldn't the new center just be a sealed design to negate any and all problems with where the ports are placed, and enginered to hit the same bass extension as the ported center?

It has?? The point of a port is to extend the bass response of a speaker. Get rid of the port and you raise the low frequency 'cut off'.

yep, now as Cam mentioned why can't the ports be placed on the sides? Would this reduce the overall integrity of the cabinet? Or, possibly would there be room on the front?

There is a difference between ported and sealed as Andrew and FredK state. There are always trade offs Micah.

I think you might be confused with posts made by the likes of myself and Johnk that debunk statements and other subwoofer myths that are commonly thrown around like sealed subwoofer designs automatically "sound better" because they are "tighter" and "faster" for music than a ported subwoofer design. I know those issues on ported vs sealed have repeatedly come up here many times on the forum regarding subwoofers.

I've seen that discussion regarding subs, but not about speakers. Something else that comes up often is how close to a wall a sealed or ported speaker can be placed, and the answer is pretty much the same if my understanding is correct.

Just to be clear those discussions on ported vs sealed did not discuss extension but rather general notions about "musicality", "tightness" and "quickness" and other misused terms about subwoofers and the idea that is spread around that sealed subwoofers are always better than ported subwoofers for music listening. It is not necessarily the case.

I hope this clarifies things.

Ok, well while we are clarifying things, let's make it clear once and for all just what the differences are.

I for one had always had the understanding that ported designs were more efficient in producing lower bass, and moving more air because they made use of both the air being moved from the front of the woofer cone, as well as the air being moved from the back of the woofer cone via the port. And that sealed designs were more efficient in producing clearer bass due to the absence of 'port noise' that plague ported designs.

Now those were the views I held previous to becoming a member here on AxiomAudio.com. Since then I've come to the understanding that the end result in performance has nothing to do with the box design, only in the enginering of the equipment incorporated in such designs. So this is the information I've been passing along to others. Somewhere in the process I completely missed anyone explaining that ported designs have lower bass extension. And I've read pretty much every thread in this forum over the past year and a half. So if I missed it, I'm sure there are many other's who missed that as well.

This is in fact the 1st time I've heard it acknowledged that there are any advantages and/or disadvantages to the box design. That's not to say it has never been acknowledged before, just that this is the 1st time I can remember seeing it. So then what is being explained to us now is that ported box's hit lower bass notes? Is that what is meant by 'bass extension'? Please excuse my ignorance, I'm just tryng to get a clear picture of the differences between the two. And if ported box's produce greater bass extension, then what exactly is a sealed box's inherent characteristic?

The information all seems so contradictory sometimes. For instance my EP800 is sealed, yet produces lower bass extension than the ported EP600. Does this mean that a ported EP800 would have even greater bass extention? And if so, then what was the reason to use a sealed box?

Enquiring minds want to know. Up until now I thought I had finally come to understand that when a newbie popped up on here claiming, "I prefer ported box's over sealed box's", that he didn't know what he was talking about. Now it seems entirely possible that he prefers the greater bass extention of a ported box.

Clarifying the differences between these two designs would save a lot of confusion for me personally, as well as many, many others I'm sure.

The EP800 has lower bass extension than the EP600 because the EP800 has two drivers and therefore double (or 113.4 sq in) more driver surface area. This would be equivalent to a single 17" driver.

My, admittedly limited, understanding of ported speakers vs sealed(not referring to subwoofers, but woofers/mids) is that the ported speaker reaches lower as has been noted, and a sealed speaker gets it's "tighter" or quicker(accurate?) reputation from the fact that it is always supported by the air pressure within the box which causes the woofer to return to it's static position more quickly.

Also a sealed sub can still produce the same bass extension given the proper driver size and a HUGE amount of wattage behind it. A ported design is just easier to run and design to achieve lower bass extension or high output, also a ported design allows the user to tweak the port opening, ala my PB13, for more output or lower extension.

Size of the enclosure matters, too.

Look, there is A LOT of science in loudspeaker design, and you can't just reduce it to one factor (cabinet design) and generalize to "all".

Not ALL ported designs have greater bass extension than similarly sized sealed enclosures. There are dozens of other factors at play.

In addition to the excellent points made by Jay, Steve and Adrian, you also have to consider potential tradeoffs relative to SPL v. extension.

If loudspeaker design was "easy", people wouldn't get paid to do it or write books about it, or surf the internet all day.

That's pretty much what I figured. But where I start to lose a clear understanding of the way things work is, if they're using 600 watts to move the one woofer in the EP600 in a ported design, which is more efficient than a sealed box, then I would have thought the EP800, which uses a less efficient design, would require more than 400 watts per speaker to even get close to the output of the 600.

I was very surprised when the EP800 came out that it was only their second sealed subwoofer. I'm very interested to hear, from one of Axioms designers, why they chose to go with a sealed box for the 800 instead of porting it like most of their subs, which produces greater bass extension. The way I'm understanding things now it just seems like it would have been easier to achieve their goal performance with a ported box.

If in fact a ported design holds an advantage in the area of bass extension, then I'm curious why they would take what seems like 'the harder road' to getting the EP800 to hit those awesome low bass notes that it does. And why it doesn't require gobbs more power than it does to perform the way it performs.

I'm certainly not trying to be difficult here, I'm just really mixed up in the reasonings behind all these decissions because my understanding of the differences between the two designs is very fuzzy. I've thrown out all the information I had on the subject growing up because it seems it was all based on myths. But so far, all attempts I've made searching for the differences via the internet seem to conflict with the information I've gotten here.

Which is why I'd love to hear it from the horses mouth. What advantage did the sealed box used with the EP800 have?

Micah,

This excellent link below that I have posted many of times will explain all the details you want to know about subwoofers and how they behave. While it is long and can get quite technical bear with it. In the end you will be able to take out of it a general answer to all of your questions you are seeking.

http://www.audiopulse.com/know-how/subwoofer-driver-guide/myths-about-subwoofers/

Mr. Link comes to the rescue again.

Thanks for the clarification Micah. I understand now where you are coming from.

I was thinking more of the quality of sound, and there, two similarly well engineered subs or speakers, one ported and one sealed, will not sound any different.

If you look at a frequency response graph for a sealed vs ported design using the same driver and without and equalization/dsp you will immediately see the difference between the two designs. The seales driver will roll off more gently as frequency drops. The ported design will 'fall off a cliff' below port tuning.

From there, the driver design and the goals of the designer dictate which direction to go.

As a general rule, with a sealed sub, you trade off size for efficiency/power. This is the main reason sealed subs remain popular. Not everyone wants a large box in their livingroom.

Hey Beavis, Tom said size matters, he he he he he, fire fire.

The speakers are wired in parallel and the amp achieves that much power, even more, IIRC.

You also have to consider how Axiom produces their lineup and to add another box design might be more costly than to simply router out a second hole in the already large cabinet of the 600 turning that cabinet design into a sealed unit.

We seem to have a different approach on this forum, straight talk and no myths.

I believe it was Ian that mentioned using the 600 box and amp due to the factors I previously mentioned way back when it was first introduced.

Whoa... FINALLY!!! That's what I'm talking about. I believe I can form a pretty solid foundation of education about sealed vs ported design characteristics based on that explanation alone! Why has it taken me so long for to find that tid bit of information? I'm not saying everyone's been hiding it away from me or anything of that nature, I've just never been able to find that sort of description anywhere!

Thanks for that. Ok so now on to my next real weakness in audio knowledge... It was said that the twin woofers in the EP800 are hooked up in 'parallel'... So does that mean that they each receive the roughly 800 watts put out by the amp? That's another thing that I've never truely understood, the laws of division and multiplication when it comes to electricity.

Say for instance an amp puts out 1000 watts and you hook one 8 ohm woofer up to it, now its driving that woofer at 1000 watts. So when you hook up another 8 ohm woofer up in 'parallel', they both get 1000 watts, at a 4 ohm load? Is that right? So in other words the two woofers in the EP800 are actually being driven harder than the one woofer in the EP600... Yes? I had been thinking that with the amp being an 800 watt amp, and there being two woofers to drive, that they both only got 400 watts a piece.

Hmmm... I may just grasp these concepts after all, provided I'm right in both of those assumptions. If not, then perhaps I'm a hopeless case!

Well, unless the amp is turned up to maximum gain, with a signal at maximum gain, no driver is getting 1000W or 800W, regardless of how many drivers are hooked up.

Yes Micah, you continue to discuss amplification as if the maximum output capability of an amplifier had something to do with how much power is actually used, despite much info to the contrary having appeared here. At a typical comfortably loud average listening level in the mid-80s of dBs, more like 1 watt, rather than 1000, is used.

If two drivers are driven in parallel, each uses the same amount of power and since they would put out at least 3dB more sound level than a single driver(of the same sensitivity)using the same amount of power, in order to keep the same sound level the power to the parallel drivers could be reduced and they would be driven a little less hard.

One of these days it will sink in John.

Take a gander at some of these sub drivers (scroll down).

http://www.tcsounds.com/index.htm

Stop right there! Just because an amp is rated for 1000W doesn't mean it is actually putting out 1000W the moment it is powered on. Maybe that's where your confusion lies. A 1000W amp paired up with a woofer does NOT mean that the woofer is being driven at 1000W. The amp does not "drive" the woofer in that sense, instead the woofer draws on the amp.

Here is a loose analogy. Think of an amp like a big magical well (of water). Let's say the well is capable of supplying 1000L of water. If one day you're thirsty and you go to the well for some water, you don't get hit with 1000L of water do you? No, instead you simply pull up and/or drink up as much water as you need in order to quench your thirst.

Likewise, a woofer (you) will only draw as much power (water) from an amp (the well) as needed in order to acheive the desired volume (quench your thirst).

I was using a 'max gain' scenario in my example, just for shits & giggles.

Good people understand that was not an attempt to say that the EP800 is ALWAYS pumping out 800 watts to each woofer 24/7. I was merely using the 'maximum output' scenario to understand the way power works. My previous understanding was that at maximum output of a 1000 watt amp with two drivers hooked up,each driver would consume 500 watts a piece.

So in that example I gave, I was showng off how wickedly knowledgeable I've become as I'd finally come to understand that they would both draw the full 1000 watts (at maximum output) that was available. Not divide that available power between them.

To add to the humor portion, I'll throw in this hardly related story.

I once tried using the water analogy on a coworker in trying to explain the difference between what our company describes a "access speed" vs. "service speed" on fiber circuits.

My explanation:
If you were building a house and needed some pipes to get water from your well to your sink, there would be different size pipes.
Lets say instead of MB per second, we are talking water so lets call it "liters per second." You know you need to be able to pump through 5 liters per second at your sink ((yes I know that's a crazy number.)) That would be your desired "Service Speed".

When you go to the hardware store, the pipes come rated for only two sizes, the small one is 10 liters per second but the bigger one is rated for 100 liters per second. These pipe sizes are the "access speeds."

Either one would support your smaller service requirement of 5 LpS but the bigger one is going to cost you more. However, the smaller one will be limited to a max of 10 LpS, should you ever find a need for much more water flow later on.

Her Response:
"Ohhh, I get it. So the Access speed is the size of the pipe and I'd only need a 100MB pipe if I needed more Service speed than what the 10MB pipe can hold." (Yeah, I think shes got it!!!)
"But what is the water for, to keep the fiber cool?"

(DOH!!!, slaps forehead and gives up.)

The water analogy works well for describing electricity, but the way you've presented it here paints the wrong picture. Speakers do not draw anything, they are more of a flow restriction than anything else.

I've been meaning to write this up for a while. Consider this my first draft.

As I said the water analogy works well. So lets assign some common water works parts to an amplification/speaker system.

The electric grid is like a reservoir feeding a large area.
The power supply in an amp is like the a water tower covering a community.
The capacitors would be like a pump in a house.
The output transistors are a valve.
The speaker is plumbing after the valve.

We'll ignore the voltage/current thing for now, and I'll say power. But if you want to think about them, in terms of water, voltage is how much water there is, and current is how much pressure is behind it. You can have a lot of water at low pressure, and it'll just flow calmly, like a sewer pipe. Or you can have a little water at very high pressure, and it can be used for cutting, like a water saw.

The electric grid has a pretty much unlimited supply of power from the point of view of the amp. But only part of that is being made available by the power supply. You can't draw any more than power supply makes available at any given time. But if you need a little extra push for a short period of time, you can rely on the capacitors.

Most multi-channel amps have one power supply, and one bank of capacitors for all the output transistors. Think of the output transistors as a number of push-button valves. They're all fed from the same source, if you open all of them at once you'll come closer to exhausting the supply. But even wide open they can only flow so much. The reason I said push-button valves is because of what they're doing. Think of a valve that automatically springs shut when you stop pressing on it. But the harder you press the more water that flows at the time. The pre-amp stage is what's pressing that valve open. It's taking a little action, the desired output waveform, and causing it to be amplified by opening and closing the valve in the same pattern.

Finally after the valves there are a series of pipes. If a speaker has high resistance those pipes are narrow. If it's of lower resistance then the pipes are bigger. If you connect two pipes in parallel they'll have half the resistance of a single pipe.

Here's where the analogy breaks down. Water vales don't suffer the same was transistors do when they're turned wide open, and have big fat pipes behind them. But if you can imagine the water being damaging to the valve, and the valve itself not being designed to flow into an open space, but only being spec'd to use a specific diameter of pipe or smaller you can get a better idea of what happens with a too low of resistance speaker.



As I said, first draft, just off the top of my head.

LOL

Well, except for the day that nobody else is home and you decide to crank WOTW to bask in the LFE glory. Then that other 999 watts becomes useful, at least for a fleeting moment...

From what I understand of amp ratings and design, a 1000w amp is not designed to output the whole 1000w continuously for hours on end. That is not what music content demands and that is not what engineers design to.

When was the last time you guys mentioned the VP160?

Chris, I've emailed that post to myself so I can read it carefully when I have more time.

In the meantime, though, THANKS!

You're welcome. Please ask for clarifications where needed.

Club Neon,

Great analogy; I've used it myself at times. I think you got the voltage/current thing reversed, however.

Voltage provides the "push" or pressure behind the flow of water; current, in amperes, is like the diameter of the pipe. A big pipe, like a firehose, enables a big flow of current. A narrow pipe restricts the flow of the water.

Big fat wires like jumper cables carry tons of current "pushed" by a low voltage (12 volts in a car).

Cheers,
Alan

Hi Jay, Micah and all,

quote:

"If in fact a ported design holds an advantage in the area of bass extension, then I'm curious why they would take what seems like 'the harder road' to getting the EP800 to hit those awesome low bass notes that it does. And why it doesn't require gobbs more power than it does to perform the way it performs."

In chatting with Ian during the development of the EP800, the main reason he mentioned in using a sealed box was because if it were ported with the super low frequencies involved, it would be impossible to control port "chuffing" and noise.

So he went the sealed box route. In doing so, sensitivity is lost because you're essentially throwing away all the back-wave energy, so to get the sensitivity back up, he used two big drivers with dual voice-coils on each, wired in parallel. By doing that, he was able to extract the maximum amount of power from the amplifier because the impedance of the two drivers' dual voice coils was around 1 ohm. So we didn't lose out in sensitivity.

Regards,
Alan

Thanks for the information Alan.

Good info about the reason for the sealed design. I keep forgetting about port noise, as I never encounter it with my system nor at Mojo's.

Alan, I always really appreciate how concise and informative your posts are. Thank you.

How come no one has posted something like this to one of MY posts?

Yes, your square room sucks.

All better now?

If the amp is rated at 1000 watts RMS then it should, if the peak power output is 1000 watts then no it shouldn't. JC told us that they run their M80's at 800 watts for several hours on end to 'tourture test' them to make sure they don't break. I would be interested in knowing which amp is used in this tourture test?

Ahhh, so he was able to squeeze out the whole 1 watt eh?

J/K


Excellent information Alan, exactly what I was looking for. You have indeed cleared up many unanswered questions for me personally with that explanation, I thank you for that. And in fact the reasons you give actually give my old beliefs in subwoofer box design differences credibility. If you go back and read the beliefs I 'used to hold', I said we car audio junkies prefered ported box's because they ultimately put out more bass. I didn't know why, but with your definition it seems this is because they are more sensitive. With less power we were able to achieve greater amounts of air moved as we made use of the 'back wave energy'.

But just as Ian explained to you, along with lower bass notes, we got a lot of port noise that interfered with the music. Which is why sealed subs were considered 'clean' and or 'tight', because there was no port noise to contend with.

Anyone that wasn't into car audio won't understand any of this. You see at least back in the 80 and early 90's you couldn't find 'all-in-one' car audio subwoofers. You bought a woofer (usually a JL Audio or Kicker), an amp (most people bought amps that made 500 to 1000 watts), and then you either bought (or made) a sealed box or a ported box to put it in. We certainly weren't engineer's, we were just kids who liked to give our back seat passengers back massages while cruising the strip. And with the three ingredients listed above, those of us who liked 'clean' bass used a sealed box. Those of us who wanted the most bass you could possibly create used a ported box. It was as simple as that.

And I'm assuming a lot of people who come on here who say they prefer the 'clean' sound of a sealed box is from that very same school of audio education that I came from. Given a generic driver and a generic power supply you're going to get more bass out of a ported box, and a cleaner sound from a sealed box.

Since those days hundreds of subwoofer companies have refined subwoofer box's remarkably. They now include a built in amp, and drivers that are either very sensitive or not so sensitive to accomodate the box design being used. This is why so many people on here tell those people who come on here exclaiming they prefer one design over the other, "there is no difference". Because with today's subwoofers there isn't.

But perhaps, just perhaps this information can help bridge the two schools of thought so that they can understand where each is coming from. Thank you for chimming in on the subject Alan!

From my understanding thats not how the amp ratings work. I have started a separate thread about amps and power here to respond to your last post.

Pretty interesting, and quite frankly shooking information indeed. If amps are only designed to produce 1/8th of their rated power for a continuous amount of time, then I'm very curious to know what sort of amp they hooked up to their M80's during the Axiom torture test chamber excersize, during which they ran them with a full 700 watts (or was it 800?) for hours on end to make sure they wouldn't break.

It couldn't have been their own A1400-2, as the most it could put out at a continuous rate would be about 175 watts.

the diameter of the pipe would be the guage of the wire there for the resistance of the wire used.. the current would be the amount of water flowing past a certian point. voltage would be the pressure that the water tower had to offer.


if you have a lot of pressure, with low resistance you have a lot of flow...



nothing like describing electrical engineering principles over the internet on a HT forum??!!!???!!!

That analogy works well, I'll steal it.

A HT forum is a good place for EE. Having a little practical knowledge of how electric works helps remove the "magic", and allows consumers to avoid snake oil.

I've got some skunk oil I'd like to sell.

hey to sell skunk oil effectively you

1) need to make the package REALLY pretty
2) sell in boutique stores, or have a special area made in a retail chain...
3) charge a shit load of money.....


now go forth and make lots of money!!!

oh, one thing i did notice neon, no one has used any equations to try to explain anything......

i though about a few, but figured i be better off sticking with the water....

The KoolAid is much better

The water model does make things relatively easy to understand. The one thing that it doesn't answer for me is, take my QS8's.... If placed within 10 feet or so they only require 16 guage wire, (or a very narrow pipe). But in my situation they are about 40 feet from the power source, so I was advised to go with either 14 or 12 guage wire (a thicker pipe).

Is this because the voltage supplied isn't sufficient to "push" that current that far? Or is there another property of electricity that the water model doesn't account for?

My guess is the latter, but I'll wait for the experts to chime in.

It is the resistance to flow of the smaller gauge wire, over long distances, the smaller wire builds up to much resistance within itself over that length, while a larger wire has less resistance over a longer length. We are now getting into new terminology here as well, inductance, impedance etc. the finer qualities of electrical theory.

I know there is some loss with longer runs of wire, which is probably where those equations Dakkon eluded to come in to play.

That's pretty much it. Lower gauge wire has less voltage resistance per foot. When you have more feet of wire, you need lower resistance to keep it below 5% of the impedance of the speaker.

Oh joy!!!!

Electricity has always been a mystery to me, having never studied it. These explanations are very enlightening indeed, and in fact even fun to discuss. It makes me want to study it further just for the sheer joy of it....


Uh oh, was that a nerdy thing to say?

Yup, here is a quick link to some:


http://www.epanorama.net/documents/wiring/cable_impedance.html

AAAARRRRGGGGG!!!!!! Damn this hobby for turning me into a nerd!!!

Where do I pick up my mandatory pocket protector? Oh, I don't have to turn in my sportbike, do I???

Mm. I think with a sportbike, you're halfway there anyway.


::runs away laughing::

this comes from a guy with a Volvo wagon and a Honda Civic.

So, the VP160 will be an underwater speaker, then?

Cool!

I hope it's a sealed design then.

No no no...

If it's ported, it will make bubbles!

Well that's reasuring. So what do we nerds do for fun besides study electric theory anyway? Run around in packs beating up jocks?

Oh, and I bet we know how to grow the REALLY good weed as well don't we! Man I think I'm really gonna like this whole 'nerd' life after all!

That would be cool for fishtanks, maybe playback whale song or other fishy melodies.

micah, you think think about it, like when you go to a fast food place.. you hope they give you the big straw, so you can drink your liter of soda with ease... but those places that give you the thin puny straw, you REALLY have to work for that liter of cola.....


So you want a larger straw...if the straw was wire...

This is why my L/R/C all have 10 gauge wire.. is it over kill yup... but its like drinking cola though a fire hose.. NO problem....

and yes, the equations range from simple algebra, to calculus level and then some....

Oops. I put this in the wrong place.

No. I didn't. I'm putting it back.

One quick question, off topic, but concerning electricity. My sister's window air conditioner is a 110-120 volt 3 prong plug that I've recently installed a 3 wire receptacle with ground. Before it was just a 2 wire receptacle.

Both before and after I did this, the plug itself gets hot to the touch. What could be causing this? Is it's because it's an old air conditioner? She rents a small apartment and the land owner supplies the air conditioner.

Edited: I said Plug where I meant Receptacle.

If the cord has been pulled on the plug, there may be some broken strands, and thus less wire making the connection, and higher resistance. It is possible to cut the plug off a cord and wire in a new one.

It could also just be that the air conditioning has that high of a current draw that the plug is going to heat up no matter what. My (1500 Watt) blender has a really thick cord, and a well designed plug, but if I run it for 5 minutes the plug gets kinda warm.

The A/C compressor draws alot of power and this creates heat in the plug, especially if it has a long on cycle. Electricity moving through a wire creates heat, throw in a little bit of extra resistance/arcing due to a marginal connection and you get even more heat. If you replaced the wire plug in an attempt to cool off the wiring, try changing out the receptacle, it could be worn and the plug-in isn't making a good connection on the spades, but chances are everything is Ok and the heat is normal.

Receptacle is what I replaced. When I said plug, I meant receptacle. Sorry.

there could be a high resistance connection between the air conditioner and the outlet, this will cause the local connection to over heat... or the wiring in the wall could be an inadequate size. how many watt air conditioner are we talking??

if anything you could always cut the plug off and get another one and put that on the wire. if it is only the plug on the air conditioner that gets hot i would cut it off and replace it.

Good point. I'll replace the plug the next time I get a chance.

I don't understand how a center channel speaker could be an underwater air conditioner.

You guys make no sense.

Ok now that everyone here has received their IB (internet bachelors) degree in electricity, back to the VP160.

I was imagining the VP150 with two 6 1/2 inch drivers to replace the 150's 4 1/4 drivers, set in a cabinet the size of the M60 & ported. However I don't know that this center would be ..

A. different enough from the VP150 (same total number of drivers). And...

B. similar enough to the M60, as it would have an extra tweeter.

The design would be 'tweeter/6 1/2 driver/4 1/4 driver/6 1/2 driver/tweeter'. ButI don't know if the timbre match would work or not with the extra tweeter? The other model discussed with the tweeter over the 4 1/4 inch driver would pretty much be the only other possibility I can think of that would work. And the different shape would indeed give people more options for space limitations.

sorry it took me a minute to post, so now that its the receptacle that is overheating. you could try to put the air conditioner in another room and run it for a little bit, see if that receptacle heats up. if it does then that is a good indication that your air conditioner is drawing more power than the wire in the house was designed for. do you know what size of wiring is in the house? did you notice when you replaced the receptacle? 12 gauge is rated for 23 amps. you will need to see what the rating on the air conditioner is..

depending on the age of the apt she's in, it might not have an adequate electrical system.

if you look at Wilsons center channel they use 2 7" woofers and 1 tweeter....

No. I replaced the receptacle. It's the plug that's overheating.

Aperion's 6C has the configuration I'm looking for. However, it measures 8.5"H x 25"W x 11"D and I'd like to see it a bit narrower but deeper to accommodate placement on an equipment rack.



I still think there's no compelling reason to put this into an M60 cabinet; MUCH too close to the existing VP180 in form factor.

Whatever Axiom decides to do will be based on testing regardless of configuration. I do kind of like dakkon's observation about simply making a VP100-config (MTM) but with the larger midwoofers.

How much narrower are you thinking Tom? If the drivers get to close together it can cause problems.

<pedant>
I fail to see what is so special about 7" drivers...

And the mids Axiom uses across the board (other than ABs and QS4s) are 5.25", not 4 1/4".

</pedant>

</pedant>

</pedant> dammit, it won't turn off...

It depends on where you measure them. There seem to be two conventions - one measuring the outside of the speaker frame (5.25") and one measuring across the midpoint of the surround (4-ish). Axiom uses the first method IIRC.

In an M50 cabinet ?

Oooooh, I asked that once when I was looking to replace a driver on a non-Axiom speaker.

Dammit. I can't remember which was "standard".

I think measuring across the outside of the frame is a bit more common.

"The great thing about standards is that there are so many to choose from"

with the 2 larger woofers you can get a much lower frequency with less drivers.

just a simple looking design.

It's 1/2" bigger, dude. I mean, that's something, but a whole new woofer design? Simply because Wilson uses it? Why not an 8" woofer, then?

Whoops, my bad.

this is just my opinion, will it happen, probably not. They already have the 6 1/2's designed and in stock.. and without knowing the actual frequency response of both speakers it would be hard to tell any true benifit. i think with an 8" you would not get the midbass that either a 6 1/2 or a 7 would be able to provide. For now, i have a vp-180 on the way, and look forward to seeing what that has to offer.

Right, John, an M50 Center. Oh, wait, they already have a VP150. Wow, that complicates things.

Jay, I guess I wasn't thinking very precisely. My perception is that the VP150 is inordinately long, but it is only 27.5. I was thinking of something "shorter" than that.

Wouldn't going bigger affect dispersion?

Hmm. So what you're saying, Tom, is a center that's a better match for the M80s but would still fit on top of my 27" CRT.

I'm there for you, buddy.

Can you have them make it really short vertically, too?

Hey, wait, YOU'RE the one with juice, not me.

27 inch CRT eh? Wow... well if the whole 'compensation' theory has any merrit, then Ken you must have one ENORMOUS dick!!!

try </pendant>

I'm with you Tom. The VP180 works for those with a dedicated HT that has space, but it would be nice to have something a little more compact to choose from. People could then choose between the VP160 and VP180 based on their space constraints.

John, I believe that the measurement is nearly always stated as being to the outsides if the speaker frame. Although measuring to the middle of the cone surround would be an attempt to show the actual effective radiating diameter, I've rarely seen that measurement.

Yeah, Tom; I'd also tend to agree. In my view generally the same speaker as the mains, from M0 to M80, subject to available space for a vertical speaker, should be used. If a horizontal speaker was wanted, for a "big" one only the VP180 is needed. For a smaller one, instead of the VP100 and VP150, W T/M W configurations, such as Aperion and others use, would be suitable.

Well there. Its settled then. Axiom, make it so!

Well, it may *seem* like a good idea, but if it doesn't sound right, it'll (appropriately) never see the light of day.

Who said it was right? We are spending someone elses money here right?

I'm really good at spending other people's money.