Axiom Home Page Forums General Discussion Stereo Subwoofers

I know this question has been hammered to death, and I don't want to add any more complexity to it, unless one of the Forum members feels that more parameters should be addressed.
Do I buy a EP350 at ~ $650, or a Velodyne DPS10B at $399 (Future Shop just put them on sale - regular price was $699).
Is it worth buying a sub with a DSP in it.

Thanks

Well, I don't think either of those have a DSP, so....

The EP350 doesn't, but the Velodyne DPS-10B does.

http://www.futureshop.ca/catalog/proddet...372&catid=10554

Shows what I know.

I don't want to sound like I'm an Axiom fanboy, but several things concern me about that sub:

--With 158 ratings, it's not rated very high,

--the frequency response is rated to 28Hz, but with no +/- tolerance listed, that's pretty much worthless, and

--the Velo has a 185 watt am VS. the 300 watt amp in the Axiom.

--Also, if it matters, the Axiom is available in other finishes than black....

Those are excellent points, Mark.

I agree.

Mark: Thank you. I see you have an eye for easily overlooked items.

I think you just made up my mind for me.

We forgot to add we need someone to get the new EP350 so we can get a review of it

Yep. We all think it's going to be really good, but AFAIK none of us have actually *heard* one yet.

I would get the new 350 from Axiom, much better then the previous model, and not much more in price.

I have never seen an audio shop setup to perform an A/B test synchronously; that is to say, evaluate two speakers almost simultaneously. I have also heard from an audio salesman (who looked well-seasoned) that memory retention of music lasts only a few minutes, or is that seconds.

So the question remains, how do we perform the evaluation.

Thanks sirquack. I seem to be getting the overwhelming opinion that Velodyne is not well liked (or is it that particular model).

Velodyne makes nice subs, I was just saying if your considering the older version of the 350, you may want to look at the new enhanced 350 which has better performance.

Velodyne makes excellent subwoofers make no mistake about it. They have been making subs since the early 1980s, longer than any other audio company. Velo's DD series pretty well set the stage for DSP controlled subs. I own a couple of Velos and am very happy with them, then again I own quite a few subs including Axioms that I enjoy.

However, I would pass on that particular Velo for different reasons than indicated above. Slot ports, such as those on these subs are notoriously noisy because of air turbulence from their sharp angled corners. But they are cheap to make and do provide extra output. If you compare it to the rounded vents on the 350 the Axiom will have far less chuffing at higher SPLs than a Velo DSP-10 or DSP-12 for that matter. The extension is also much better with the 350. No contest stick with the 350.

The Polk PSW505's have a slot port too. Is this a trend, or just plain laziness in the manufacturing process. I'd hate to think that a company would "compromise their design over a couple round holes.

Slot ports generally have edges and that is the main reason why they contribute alot of noise relative to round vents. Slot ports with rounded internal joints (no edges) can be very effective in moving air with minimal turbulence, same as a flared cylinder but that is not the case with the DPS-10 and many other slot ported subs. I also suspect that if they didn't round the edges outside then the inside opening will also not be flared. If that slot is similar to many slot design it will be angled at 90 degrees inside the enclosure.

Here is another take on why that is not a good characteristic if you don't mind some of these fluid dynamics principles, so bear with me in the physics below.

There is huge pressure inside that big box during loud passages. Inside the enclosure, air tends to slow down along the four corners of the port causing the air flowing along the middle of it to become more unstable or gusty. The 90degree angle of that edged slot port will also create unlinear air velocity (more artifacts) which in turn adds to internal air turbulence. If that isn't enough as this unstable air exits it must flow over another edge creating eddys and more turbulence as it abruptly contacts the stable air boundary outside the opening. The net result is uneven FR, resonance at higher frequencies which colours the bass, and other noise/distortions. Chuffing may or may not be detected but at high output the effect of these unlinearities will be evident compared to a flared rounded slot or a flared cylindrical port.

The slot port design can be improved by adding flares at both ends but that is more expensive to accomplish with a slot than a round cylinder hence why the cylinder ports are so popular. Flares help by compressing air into the body of the port inside the sub and expanding it upon exit. Because of this compression/expansion of air the length of the port can handle higher inner-port velocities without increasing the mid-section diameter. The angle of the flare is important and it needs to be a minimum of 45Deg along a circular path to achieve this type of airflow. Some people would suggest the flare curve needs to be parabolic but that's another story we don't need to get into right now.

The problem of internal edges also needs to be addressed. It gets expensive but the slot can be made effective if its internal and external edges are rounded and flared. In effect it increase laminar flow causing it to behave much like a cylinder.

Bottom line is avoid slot ports and especially slot ports with edges. Notice how well designed the Axiom sub ports are. Its one of the many underappreciated features of these subs.

John: From Klaus audio http://www.klausaudio.com/subwoofer-box-articles/flared-ports-vs.-slot-ports.php

"Many people question what the difference is between flared ports and slot ports. There are fairly basic differences between the two, and depending on your situation, one might suit you better than the other. The common purpose of the two ports is that they must be the correct length for the particular subwoofer box to achieve the desired sub box tuning. There are a few differences that may help in your decision between flared and slot ports for your custom subwoofer box.
Flared ports are very good at virtually eliminating port noise. Port noise is the noise created by the friction of air moving through the port. If you have sharp edges on a port (as with standard round ports, which we do not use), you are going to have significantly more port noise than with a flared port. A flared port requires the smallest acceptable port area for a subwoofer box. Since the ends are flared, and the inside of the port is round (no sharp edges), it is unlikely you will be able to notice any port noise from the subwoofer enclosure. However, if you are running a large, high-powered subwoofer, you will want to use two flared ports. A single flared port is still capable of creating port noise when very large amounts of air pass through it.

With a slot port, you can use as much port area as needed for your application, which is especially helpful in SPL applications. A slot port requires more port area than a flared port to minimize port noise. We generally use a rule of 12 square inches of port area per cubic foot of internal volume of the custom sub box. You may go with a larger port area, but this will increase the total volume and length of the port. In turn, a large port area will mean an increase in the total size of your subwoofer box. Slot ports are the standard for our ported custom subwoofer boxes.

If you are not limited on space, we would recommend going with a slot port for your subwoofer box. If space is tight, and you have a few extra bucks, you'll probably want to use a flared port (or two, depending on your subwoofer size and power). It is possible to achieve the same result from both subwoofer boxes, so the decision between flared ports or slot ports depends on your specific needs for your custom subwoofer box."

John: Another question comes to mind in regards to ports. If the vendor elects to use a slot, why doesn't he just put a chamfer or bevel the on the inside and outside edge of the enclosure, which is easily done with a router.

Because it adds to the cost. Rounding the edges is highly desirable but I've found that cheaper subs have slots to keep the cost down and most have edges so you get more port noise. Also it isn't just the outside port opening that needs flaring, its also the internal opening.

The author of the above article is correct in saying ports and edges should be flared or rounded to minimize port noise. What he isn't saying is that most slot openings are edged or have a 90deg edged joint inside the sub which is never rounded. Relative to flared cylinder ports, edged slots are a very cheap albeit noisy way to get SPLs.

Ports are a necessary evil in a high powered sub and the best designs avoid edged slots for flared vents in order to keep noise and resonance as low as possible. The Axiom vortex ports are as good as I've seen or heard on any vented alignment.

Do these arguments also apply to your primary speakers?

Never saw a speaker with a slot port so I wouldn't know.

All this talk of ports and angles has me thinking I need to bring out my cylinder head porting and polishing kit to see if I can manage a few more DB out of the EP400

By all means, but don't hurt yourself.

Ah, but remember that the EP400 originally had a port, and Axiom elected to take it out. Presumably there was a reason.

I believe that given the size of enclosure and the power of the DSP circuitry there wasn't any advantage in terms of output to going all sealed.

Perhaps there was an advantage in sound quality.

I agree with John. Given such a 'drastic' change, the speaker would have undergone many rigorous tests, and presumably, the current design reflects superior performance in its present configuration.

Question: Without a port, is the speaker now considered a sealed box? If so, wouldn't it have to have been made larger to obtain the same SPL as the older model?

the ep400 had an older model?

There indeed was an earlier version with a port. I believe it wasn't up to Axiom's standards so the port was nixed.

I never ever hear anyone talk about the distortion the subwoofer DSP injects into the music. And if that is true, which I am sure it is, I would have thought that everyone would be buying passive subs. Am I missing something fundamental?

I just thought of the obvious answer. Subs take a lot of power, so it's going to suck it out of your amp, or you're going to have to provide the the sub with what it wants.

Just the same, do you see specs published on the speaker's integrated power supply, the same way you would on an amp?

When a band, or orchestra, or vocalist makes a recording, the music generated must go through a mic, preamp/amp, mixer, and some kind of encoding. It then gets pressed, and when you listen to it, it passes through CD player, preamp, amp, speakers, and sub if you have one.

The recording stage is a mess of a lot of wires criss-crossing, and most of the electronic equipment contains a lot of op-amps, which is a no-no for the purist. Finally, the speaker is the greatest source of distortion, and the sub probably even worse. So why does debate on these subjects usually involve the criticism of one component, when clearly the rest of your system has contributed considerably more distortion.

I think I'm going to have to start some serious auditioning. Every sub I've ever heard ruins the music I'm listening to. I have a pair of M60's, and they are a delight to listen to at all volumes, including excessively high volumes. Add a sub, and the experience is ruined, which begs the question: Do all these audio places have their subs set up right, or are subs putting out distorted crap, which people have been trained to accept as good.
This has been my experience. I am not claiming subs are crap, but everyone that I have ever heard sure sounds like it. And if these audio guys are trying to sell product, you'd think the theater room would be set up right, wouldn't you.

Hi Mark: 185 Watts vs 300 Watts, is only 2 dB.

What subs are you auditioning? And yes most places set up the subs way too hot to emphasize the pound which is what the general public seems to expect from a sub.

The EP400 is an absolute delight for music, it is not overpowering and blends seemlessly withe M80s. I would bet it would work just as well for the M60s.

You may just need 2 subs, one for music and one for HT. The EP400 just doesn't have enough air movement to shake the house for HT but just fills in the lower end when listening to music.

While I was searching for my first sub, I was given a PSW 505.

I agree with Jakewash that general public is looking for the big boom when shopping. You mentioned above that the subs you're listening to are in theater rooms, so most likely they're set up for movies and are running hot to "show off".

Have you been able to tweak and play with the subs at these stores? Adjusting the volume/gain on the subs amp shoud help. Which models have you listened to and have you found a shop that will let you demo the sub at your house or that has a liberal return policy?

I've been very happy with my HSU whether its set up to blend or if I want to make it to stand out a little with some bass heavy music like rap. One of the other Axiom subs that has been mentioned to be really good with music is the EP175 I believe.

I agree that when you're dealing with speakers and subs, you really need to bring them into your own environment, calibrate them and assess at your leisure.

I don't think I ever said the sub was in a theatre room. Currently, it's in my bedroom, and that's where they will stay until the kids move out. There are no stores around me that carry these subs.
I have a friend in Toronto who has the same amp & sub. He says his works fine. Maybe I'm expecting these subs to do something that it can't. It's also peculiar they appear to work when connected to the LFE input. But when I use this input, it sounds like all music is being sent out, not just the bass.

Hi Hay: Sorry, I misunderstood what you were saying. None of these stores seem to carry the Polk. The professional stores (as opposed to the Big Box stores) will probably allow you to fiddle with the settings of what they have setup, but I've never tried that.
I am now starting to get the feeling that I have expectations of a sub that a sub can't supply. I think I expect the sub bass to be as clean as the M60's playing back the whole spectrum of music.
When I turn off my sub, I'm just listening to the M60's. They are a delight to listen to. When the subs are turned on again, all the music from the sub sounds poor, and pollutes the M60's. But then again, maybe crap is what the people want.

My buddy has a similar issue with his sub. He uses his pre-amp to drive a sub whose name I can't remember. When I listened to it, I could hear vocals out of the sub. So I calibrated his sub and speakers and it sounded much better. But I could not get his sub to blend with his fronts the way my 600 blends with my 80s. The best way I can describe it is that the bass sounds distinct from the rest of the music. Now he doesn't perceive this and I certainly am not going to point it out since he's now a happy man.

Mojo: I sure can tell the difference, and I'm considered tone-deaf (whatever that means).

M60's - heaven
Subs - ?xc#$

If you're near the TO area and have a buddy there, you may want to look up jakeman on these boards. He has a slew of subs and recently did testing with the EP400. I think from what you're looking for the EP400 may be the sub for you...

Hay: Well thanks for that recommendation. jakeman seems very knowledgeable in quite a few aspects of audio.

Mojo: I've never been able to blend the sub with the M60's. The only way I can do it, is to cut the phase close to zero, and set the sub's volume to almost zero. Perfect - the sub is now doing nothing, and I can listen to those sweet M60's.

Can you run an extra set of speaker wires to the high inputs of a sub instead of going in and out of the sub?

You should be able to integrate the crossover of a subwoofer with the M60s by dialing it around to the 50Hz point or so. Possibly even a bit less.
Then play around with the gain. I like to set my sub to a less than SPL equalized value compared to the M60 mains since i find most movies tend to run a bit 'hot'. For music i prefer the M60 bass anyway so a bit less from the sub works out perfectly.
One still needs a sub to hit those really low notes.

Hello bugbitten: I implemented your suggestion, but I get garbled audio. Thanks for the suggestion.

And it seems like I have to adjust the sub volume for different CDs. Is this normal?

If it wasn't so heavy, I was thinking that I'm soon going to punt this sub out the bedroom window.

Unfortunately it can be.
Each sound recording may be mixed by different companies, different sound engineers. Some may pump up the bass, some may make the recording 'hot' (more treble).
This will be noticeable across music discs.

You have to find a level of your sub that is a good blend for the best and the worst, or simply don't play the worst as often as the best.
Keep in mind THERE ARE LIMITATIONS to this audio reproduction. You may not find a perfect solution regardless of what equipment you buy!!

Hi chesseroo: If you have to tweak the sub for different CDs, it sounds like the sub excels at taking a 'good' piece of music and distorting it. If this is so, what reasonable person would ever buy a sub.

I frequently have to change the bass channel level depending on the recording. Some recordings are too hot and some are not hot enough.

I don't know if it's been mentioned but here are a couple of other things you should try. First, try increasing the level of the 60s and turning down the Polk. You may have the Polk set too hot thereby giving you flabby, floppy bass because the higher harmonics don't have enough volume.

I was going to say also try changing the distance of the sub in your receiver but I remembered that you don't have that capability. If it has a variable phase control try varying that. It could be that the timing between the sub and your 60s is off. If the timing isn't right, the fundamental and the overtones will be out of phase and it won't sound tight like it should.

If all else fails, you need to try that sub at someone else's place or bring another sub to your place to see if there's a difference.

Mojo: I've turned down the volume on the sub (it now sits at 10 o'clock), and increased the volume on the main amp. The Line In LPF has been adjusted to 80 degrees. I believe I'm making progress, but it sure is a lot of work. Some of the frustration is gone, and now it's starting to get fun.

If it's any consolation, I spent over 30 hours tweaking my 600. I discovered that I had my 600 tweaked properly within the first half hour but then I kept second-guessing myself.

Mojo: It seems I do the same. I get it to a point where everything sounds pretty good, and I should layoff. However, I always think I can make it better, and invariably, screw up everything.

Can you recommend an audio calibration disk?

Thanks to you and the others who forwarded good ideas to get me going.

Unfortunately I can't recommend one because I don't have one that is "latest and greatest". I've heard of something called Avia...maybe someone with experience on this can comment.

I use a CD that has test tones on it from 1990.

Here is a free download test tone site I used and it seems to work great. If you want to google "test tones" a ton of sites pop up free or pay you can get what you need.

I do have Avia which isn't that great for test tones but the Digital Video Essentials which I also have, has a pretty good speaker test tone array.

I know I'm getting into this way late, but I'm having trouble picturing your setup. So you've got an integrated amp with 5.1 inputs, right? It does no processing whatsoever. So the only processing you're doing is in your SACD/CD player? How many speakers do you have? How is the SACD player hooked up? Does the integrated amp have provisions for crossovers for the main speakers? If so, then it's doing processing. If not, you're in my old condition, where I was actually using tape-outs to supply signal to my sub and using the sub's crossover. Now, I didn't have this setup with really good speakers, but it seemed to work.

I find that a sub can enhance music quite nicely--even with M80s, which have substantial bass of their own.

And yes, there were subs before HT.

Hello and thanks for giving me your views. I have an integrated tube amp (made in China), which plays stereo, and does nothing else. The integrated amp has four I/Ps for CD, SACD, DVD, and tuner, and two pairs of O/Ps to drive the M60's. It also has two pre-amp O/Ps.
I have two M60's, a CD Player and a Polk PSW505 sub which was donated to me.
The M60's plug into the left and right amp O/Ps, the CD Player into the CD I/P, and one of the pre-amp O/Ps to the Sub Line In+ and Line In-.
The sub also has volume and LPF control, LFE, and four Speaker Level O/Ps.
I connect the pre-amp of my integrated amp to the Sub Line In+ and Line In-.
Let me know if you need more info. The booklet the comes with the sub is pathetic.

Hmm. So the only crossover you've got is on the sub itself. What do you currently have that set for? It's harder to blend speakers with sub when that's all you've got; the bass from the speakers has to match the sub pretty well, and the sub has to be pretty fast, otherwise you get a bit muddy. I'd probably set it around 50 or 40 Hz, given the option. Also, does the sub have a phase control and have you played with that?

I agree about using the high level inputs on the sub; mine did not play nicely with that, although it didn't completely fail as yours sounds like it did.

I also experienced the joy of adjusting the volume on the sub/cd, although since you've got it on pre-outs, it won't be so bad for you.

In your testing, it sounds like you were trying to listen to the sub by itself, without the M60s. That's going to sound pretty odd; I'd test with the sub and 60s together and try to match it up that way.

What source material are you testing with? I thought I saw something about pipe organ. While that is undoubtedly a good sub workout, the bass is not necessarily repetitive. I tend to like using Sting--Mercury Falling or Brand New Day to test it out. Those particular albums have bass that you simply won't get through the M60s (I don't get all of it through the M80s, and certainly not nearly all of it through the M50s!), and it's pretty repetitive and constant if you pick the right track. Of course, it may also drive you insane depending on your musical preferences.

I would look at house music or drum n bass if you are looking for repetitive bass!

Hi: The crossover is in the sub. I have it set for 80 Hz, but I seem to have to change it for every different CD I put in. I'll back it down to 40 Hz as you have recommended. Volume on the sub is at 11 o'clock. In regards to the phase, I've tried switching between 0 degrees and 180 degrees - no discernable difference. I just can't seem to blend the sub with the M60's. But if I connect the amp to the sub's LFE input, I get the full spectrum of music - it just sounds like an ordinary speaker.
You are right in that I was listening to the sub, rather than the M60's and sub together - I'll correct that flaw in further testing.
I'm using a lot of organ music, the theme song to Jurrasic Park, and Time Warps. My son also has some music with a lot of bass - boy is that painful to listen to.

I'll just take that gawd-awful CD my son has, and set the CD player to repeat track1. This should encourage me to get the testing over quickly.

It may just be that this particular sub is better suited to HT, and simply won't blend with the M60s. You might want to try a sealed design for music (I have a sealed 12" sub). One example I can think of off the top of my head is the EP400, but I am sure there are others out there that might suit your budget better.

That said, the SVS and Axiom ported subs that I have heard have substantially added to music. Sadly, I haven't heard any Hsu subwoofers yet, but those are supposed to be quite good for music as well.

BTW, you want to hear all of the music out of the sub, to a point. It sounds like the crossover in the sub may not be working--does the sound change when you adjust it? At 40 Hz, you shouldn't be hearing anywhere near all of the music.

Thanks for the reference.

I can't hear anything coming out of the sub at 40 Hz.

I agree with your last paragraph: "BTW, you want to hear all of the music out of the sub, to a point. It sounds like the crossover in the sub may not be working--does the sound change when you adjust it? At 40 Hz, you shouldn't be hearing anywhere near all of the music."

Polk says to send the DSP board back to whence it came.

Most likely when using the LFE input on the Polk it bypasses the internal crossover.

Ah, I was trying to figure out what on earth was the difference between the LFE input and the regular inputs.

I don't recall either, but the name LFE (low frequency effects) suggests that energy is so far down in the spectrum, that you will feel it, not hear it.
Now don't anybody take this as a fact, it's just my guess.

No, that's just the generic name for the .1 channel (bass effects) in Dolby Digital, DTS, etc. That channel need not incorporate all bass in the production, but is often used for that by pre/pros or receivers when the speakers are set to small.

In short, it's something of a nebulous term, and I'm guessing Rick has the right of it.

LFE is really for Low Frequency Effects. It is often confused with the "bass channel" inside a receiver that contains both the LFE and whatever frequencies is below the crossover. But they are distinct.

Yeah, I wasn't too clear about that in my attempt at an explanation.

He he he. I often call LFE-intensive movies as "Concerto for Subwoofer and Other Equipment"! I watched "Troy" in DolbyTrueHD on Sunday and even if I don't particularly like that movie, it was pretty sub-80hz rich!

Are you saying that bass contains LFE + notes below the cutoff? Then why does LFE have its own O/P?

Well, if the speakers are set to small, then yes, the LFE output channel from the pre/pro or receiver would include the bass from the other channels along with the content of the LFE channel from the source.

However, are you saying that your integrated amp has an LFE output on it?

LFE output is for dedicated LFE channels in a movie. Rarely (if ever) does a music source have a dedicated channel for LFE. Unless I am wrong

Multichannel discs (SACD/DVD-A) frequently have a dedicated channel for LFE.

I have 120 of them and they are all 5.0 (or 2.0, 4.0!). To have a LFE channel for music would mean that the sound engineer has decided for you what your sound system can handle. Exceptional cases like a canon firing or some other special effects could use the LFE channel, but those are rareties, not the norm.

Are you absolutely certain of that? If so, why are there 6 hookups?

Yes. The technical capabilities does not mean it has to be used. Furtermore, your player is capable of doing bass management so it needs to have a LFE output that will be used to redirect the bass to that channel that is typically connected pretty directly to a sub-woofer.

In any case (and I had to think about it myself at some point), think about it: if the sound engineer redirects some bass on the LFE, what's the xover? In case you never heard double-bass management (two different sets of xover) it is horrible. For a good ten minutes, a few weeks ago, both my Oppo player and my receiver were doing bass management, one at 100hz, the other at 80hz. The sound was soooo bad!

The 5.1 you read at the of DVD-Audio (SACD really displays that) is pure marketting. People are so used to "5.1" to mean surround that they feel cheated if they see "5.0". In the booklet, when they bother to mention it, they will ether say "unused for this recording" or "barely used", and the "barely used" is synonym with unused.

As I type, I am currently listening to a 5.0 (it is actually displayed as such on the receiver) SACD.

Hope this helped.

Oh fine...

Nope, my integrated amp is vanilla - an On/Off switch, Source selector, and volume control. The back panel has to pre-amp I/Ps. They don't make them simpler.

Jason: Thanks very much for the sound file. Now all need is a Radio Shack SPL meter. The analog ones are not made anymore (I'm) told, so that leaves the digital version ($100 in Canada).

You can get some like Mojo and I have at various places out of the states for the same money and I thnk they are a little more accurate. This is the one I have and Mojo has posted a link to the one he has, it is made by Galaxy sound, I have seen it advertised from Amazon.com and a few other places with the Avia disc, I would google for them.

Or if you live in a big city just post the city and someone will probably come over with an SPL meter...

... and maybe beer.

Jakewash's is higher quality and I believe it also has an analog output which is useful if you want to graph your room response on a PC.

You're right Mojo mine does have the analog out, I do plan on graphing my room sometime, but then again maybe not as I may find out my room is worse than Mark's.

I think my room has all of yours beat. My room response looks like a roller coaster ride.

Nah. Mark`s room response looks like the Rockies.

I guess it's nice to be known as the "Gold Standard" in something.....