Axiom Home Page Forums General Discussion Home Theater Fundamental Questions - Pls help

Sorry for the double post, but after I posted this in the "advice from owners" forum, I figured it actually belonged here...
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I am heavily researching my dedicated home theater (projection system, 24x14 sized room). However, I have limited knowledge when it comes to higher-end setups. So, if you wouldn't mind taking a few minutes, I would appreciate help with the following questions:

1. I am considering the M80 speakers. Would those be too much for a 24x14 sized room? What do the M80 speakers give me the M60's wouldn't?

2. What receiver would you recommend to run the M80's? I would like an amp that runs an 8.1 system. My budget is around $1,000. Note: I probably don't need multiple zones since it will be a dedicated HT receiver.

3. Would the receiver change for M60s?

4. Now, I had the theater pre-wired for the following speakers:
Front R&L Ceiling
Front R&L Floor
Rear R&L Floor
Rear R&L Ceiling
Right Side - 2 Speakers
Left Side - 2 Speakers
Rear Center Ceiling
Front Center Speaker
Now, lets say I wanted to run all of those speakers? Obviously a reciever can't power all of those, at least in the $1k range. How does a power-amplifier work? I assume its a post-reciever setup? Does someone have a link to a FAQ or website that describes that setup? What power-amplifier would you recommend to power all of those speakers?

5. Assuming I had the M80's for fronts, what would you recommend for front R&L ceiling speakers?

6. Is a voltage regulator or line conditioner recommended? Do you really need those? Do they make a difference?

7. How are the Axiom subs? On all of the other forums I always read about SVS, Velodyne and HSU.

8. Unfortunately my side speaker pre-wires are at least 3-4 feet in front of where I will be sitting. Is it worth it to put speakers there still? Or skip the 8.1?

9. What is the difference between 2-4-8 OHM? I am sure there is a FAQ out there which tells how speakers and receivers and OHMs all work, in laymans terms. But I can't find one...any links?

Thanks in advance! I appreciate you taking the time to answer what you can!

Hopefully once I get my Axioms, I will be able to demo my setup for all those who travel to Las Vegas!

I'll start off, then everyone else can jump in and correct me

1. My understanding is that the main difference between M80s and M60s is that the 80s can play louder (ie REALLY loud) and the bass goes a little bit deeper on the 80s. The 80s would probably be OK in a 14x24 room but my first thought for 14x24 would be the M60s. I have M60s and 13x23 room.

2. Don't know much about 8.1, but the main issue for M80s is that you need a receiver which will drive a 4 ohm load well. I think Denon and HK are the normal recommendations... with most other brands it seems like some models can handle the 4-ohm load and others can't.

3. The main difference with M60s would be that a much wider range of receivers would be able to drive them, since they are 8 ohm rather than the 4 ohm M80s. M60s are also a tiny bit less sensitive so to get the same (REALLY LOUD) volume out of the M60s you would need more power.

4. I don't know enough to answer this, but my first thought would be that having all those cabling positions gives you flexibility in speaker choice but that you would never want to use all the possible speaker positions at the same time. In the stereo world having multiple speakers driven off the same signal (eg. floor and ceiling mains) gives you more volume but blurs the imaging so usually nobody even tries. Might be different for HT -- anyone ?

5. My recommendation would be "you don't need R&L ceiling speakers"

6. Again, out of my depth. From reading other posts it seems that they can sometimes add "that last bit of detail" but they would be one of the last things to spend money on. If your area has exceptionally bad power quality it might be a different story.

7. I have never heard an Axiom sub but I have a PSB which is probably in the same league. I think the Axiom subs get a bit of a bad rep because they are just "really good" while the rest of the Axiom speakers are pretty much "absolutely the best thing you can get for the money". If you want the absolute best subwoofer performance for the dollar the HSU and SVS models seem to be ahead -- on the other hand lots of people order the Axioms, get a good-performing sub that matches the rest of their equipment and doesn't look like a big black wife-scaring lump lurking in the corner and are very happy.

Not sure where Velodyne fits in -- the sense I get is that the HSU and SVS seem to be what people looking for the last bit of performance tend to get.

8. Not even gonna try. Will watch the thread and try to learn something about 8.1

9. The whole 8 ohm / 4 ohm thing is always hard to explain from anything but a dry meaningless technical perspective... but let me try. Impedence is sort of "like resistance but for AC rather than DC". If you connect a battery (or an amplifier) to an 8-ohm load then a 4-ohm load you will get twice as much current going through the 4-ohm load, and will get twice as much power and play louder AS LONG AS THE AMPLIFIER CAN PUT OUT TWICE AS MUCH CURRENT as it was designed for (assuming it was designed for 8-ohm loads which is pretty common).

If the amplifier isn't up to driving the lower impedence load then a variety of bad things will happen if you turn up the volume -- overheating, clipping/distortion, or (more likely these days) a protection circuit in the amplifier will detect the extra current and shut down the amp. No music.

Some receiver mfgs believe that the ability to drive a higher current load is a generally good thing (slightly better sound) even if you are not running low impedence (4 ohm, 2 ohm) speakers. This high current design is what lets the receivers handle 4-ohm loads with few or no problems -- and that is why HK and Denon tend to be recommended for 4-ohm M80s.

Your next question is "so why are the M80s 4 ohm anyways ?". I don't know the answer to that one although there are a number of possible answers.

I think the sheer number of drivers makes it a lot easier to build them as 4 ohm. But that's just me making things up again.

VV, welcome, and I'll add a bit on some of your questions. 2. 3., don't know what's meant by an 8.1 system; 7.1( left, right and center in front, left and right side surround, and left and right back surround, plus a sub)are the usual full setup. In your price range two models that come to mind are the Denon 3805 and Yamaha 2500. Same for the M60s.

4., 5., don't follow what all the speaker points are intended for. You shouldn't have different speakers in different positions handling the same channel and possibly muddling the sound.

6., competently designed receivers, certainly including the ones which you'd be considering, have all the voltage regulation and power conditioning necessary done in the transformer, rectifier and filter capacitors in their power supply section; no further treatment is necessary.

8., side surrounds(when there are also back surrounds)are best placed even with or slightly ahead of the listening position.

9., 4 ohm speakers(there are almost no 2 ohm home speakers)have a lower impedance to current flow than an 8 ohm speaker and would draw more current if voltage was the same(Ohm's Law; I= V/R, or current in amps equals volts divided by resistance or impedance in ohms). As long as the receiver/amplifier is able to supply the increased current without shutting down as a protective measure, 4 ohm speakers are fine. The receivers mentioned above, among others, can handle this.

You should of seen my post in your other thread, but if you didn't....

Cheers, Jag

Hi VegasVec,

Excellent advice from all (bridgman, JohnK, kcarlile) and I have little to add except:

Do not use in-ceiling or in-wall speakers, unless you want mediocre sound quality that tonally will not match the neutral M60s, QS8s, and center channels.

kcarlile is correct: Using as many drivers as the M80 does (six), it is electrically difficult to keep the impedance curve of the system above 4 ohms.

If you want the M80s and wish to drive them hard, do not use an A/V receiver. Get a separate power amp, which will drive 4-ohm loads. Otherwise, the Denon and H/K receivers are fine with the M80s. With your room size, you'd be just as happy with the M60s. Running with a sub, there is very little difference between the M60s and M80s.

Go to the Axiom Archives and Audio Tips and Tweaks for more detail on impedance issues and related topics.

Regards,

Wow, thanks for the prompt and in-depth responses! This community really lives up to its reputation on other boards...

I don't think it matters much, but my measurements on the room were wrong...its a 28x17 room.

So, it appears that my room is considered a medium sized room and the M60's should be sufficient? I might be a little too analytical here, but I assume that the M60's would still be able to get loud and be "felt" even sitting 12-15 feet away?

I am torn, because part of me thinks it might be worth the extra $300 for the M80s....has anyone else struggled with the M60 vs M80 issue?

Also, how is the Axiom center speaker....it looks extremely inexpesnsive compared to other centers I have looked at.

Thanks again for the help.

Hi VV. I'll add a little fuel to the "M60s are more than enough" fire here and you will be happy with them in the room you have. The M80s are excellent as well, but louder is their value-add, but you must ask if you will play them loud enough to warant the purchase. Having said that, make the decision based on what makes you happy. Getting the M60s and spending the next few years of you life not quite being able to scratch that "what if" itch is a problem to be avoided. Also, the M80s would give you better bragging rights and assist your testosterone production.

Having the M60s gives you $300 more to apply to a receiver or separates. You can transfer your bragging rights to the receiver and win all the way around.

Both the VP100 and VP150 are excellent centers. I have the VP100 in a 16x22x10 room and it is terrific. Again, the VP150 soothes the upgrade muscle twitch.

When I assembled my HT setup, including my Axioms, I used the experience I have gained over time to make my decisions. Buy quality, get enough of it to assure I was happy and stop short of getting more than I would actually use, need or appreciate. I have spent alot of time wringing my hands over the decisions, but it's only HT - not life & death.

>>So, it appears that my room is considered a medium sized room and the M60's should be sufficient? I might be a little too analytical here, but I assume that the M60's would still be able to get loud and be "felt" even sitting 12-15 feet away?

FWIW, I have M2s and M60s. I set up the HT system with M60s but after some playing around realized that even the M2s (exquisite sound, just not real loud) could fill a room surprisingly well with a good center and good sub.

I moved the M60s upstairs in a stereo rig (mmm, nice) and am running M2s, VP100, PSB 6i sub and cheap surrounds (surrounds are next on the list). Shakes the room pretty darned good, since it's the sub that does most of the real shaking. Your room size is going to put a big demand on the sub(s), even more than the mains.

If I were in your shoes I would go with M60s and spend the money somewhere else. Upgrade the center to a VP150 and spend any leftover $$ on a killer sub.

Alright I agree with pretty much everything said here, and just for a bit more clarification:

8.1, heck even 7.1 and 6.1.. are *REALLY* new, and there are barely any DVD's using these decoding formats..yeah they're coming, and yeah you're future proofing I suppose, but that depends on your budget. 5.1 is just fine for me, 7.1 would be neat, but until every DVD under the sun starts shipping with 7.1 content, I'll wait, the choice is yours.

As for the Axiom center channel's, the VP150 is a very lovely speaker, it has enough oomph to scare me, and deep voices coming from it can slam into your chest.

As for the 60's, they've lovely speakers, although I haven't experience mine to their full potentional, and I know that, I'm VERY happy with them even in their current state (my room is a little smallish).

Cheers, and good luck!

- D