Have Pioneer VSX1121, need advise for external Amplifier - AVS Forum
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post #1 of 7 Old 10-04-2012, 04:19 PM - Thread Starter
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Hey guys,

So it's been a few years, and I've been playing with different things. Went through 4 different receivers and several speaker setups. Here's what I'm currently using:

Pioneer VSX1121 7.2

Center: Polk CS2 x1
Left/Right: Polk Monitor 70's x2
Surround Sides: Polk Monitor 50's x2
Rear Surrounds: Polk Monitor 40's x2
Subs: Polk PSW505's x2



Have some Polk Monitor 30's for front heights, but they're not in use because the receiver is 7.2 and not 9.2. So can't use them all at once with this receiver, but that's ok, I don't feel like they would add anything really, so they're just there for fun/experiments.

Sounds good, but I'm wondering if I'm under powering my CS2 & M70's. The M70's have 5 drivers each. When I isolate them, they just don't sound as good as the smaller M50's and M40's. Leads me to think the VSX1121 cannot output enough power to really bring all the drivers of the M70's to the same level.

Using this system mainly for home theater, and some music between movies.

Was thinking about getting a 3 channel amplifier, that does 200watts@8ohms, like an Emotiva XPA-3 perhaps.

Any thoughts on this? Would it be worth while to put more dedicated power to the M70's and CS2, then let the VSX1121 handle the M50's and M40's? I've had the Polk people tell me that I should put an amplifier on the M70's and get them off the receiver's power as they're not getting enough. But figured I'd get some more opinions else where.

Thanks!

Very best,

Source: Pioneer VSX1121 (shopping for an amplifier(s))
Fronts: Polk Monitor 70's x 2
Center: Polk Monitor 70
Side Surrounds: Polk Monitor 50's x 2
Rear Surrounds: Polk Monitor 50's x 2
Subs: Polk PSW505's x 2
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post #2 of 7 Old 10-04-2012, 04:35 PM
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Your CS2 and Monitor 70s both have efficiency figures of 90dB, so the receiver with its 110wpc is more than adequate in raw power to drive them. You won't make any sigificant improvements with separate amps in terms of raw volume, and the general character of the sound won't change either.

The main difference you probably hear is the difference in speaker design. The difference between radically different speaker design always results in a different tonal character, where the differences between power amps is inaudible except for maximum volume. However, to double your apparent volume you'd need 10X the power...in your case that's 1100wpc! Just upping the power to 200wpc will result in less than a 3dB change, hardly worth it, and that a change in the maximum undistorted volume only. With your 90dB efficiency speakers you should already have enough volume to play and louder than necessary volume.
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post #3 of 7 Old 10-04-2012, 05:05 PM - Thread Starter
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Originally Posted by has7738 View Post

Your CS2 and Monitor 70s both have efficiency figures of 90dB, so the receiver with its 110wpc is more than adequate in raw power to drive them. You won't make any sigificant improvements with separate amps in terms of raw volume, and the general character of the sound won't change either.
The main difference you probably hear is the difference in speaker design. The difference between radically different speaker design always results in a different tonal character, where the differences between power amps is inaudible except for maximum volume. However, to double your apparent volume you'd need 10X the power...in your case that's 1100wpc! Just upping the power to 200wpc will result in less than a 3dB change, hardly worth it, and that a change in the maximum undistorted volume only. With your 90dB efficiency speakers you should already have enough volume to play and louder than necessary volume.

Heya,

Thank you for that response; helps clear things up and makes lots of sense.

I am getting all the volume I need, no problems there. I just felt a little underwhelmed with the performance of the M70's I think. They didn't sound much different, or "bigger" than the M50's & M40's did when I isolate and listen to them stereo to test them all out individually. In that case, it's probably just the M70's being entry level towers so I can't expect that much from them.

Basically, it sounds like instead of spending $700 on a 3 channel 200wpc amp, I'd be better off putting that $700 into better speakers. Sound about right?

Thanks!

Very best,

Source: Pioneer VSX1121 (shopping for an amplifier(s))
Fronts: Polk Monitor 70's x 2
Center: Polk Monitor 70
Side Surrounds: Polk Monitor 50's x 2
Rear Surrounds: Polk Monitor 50's x 2
Subs: Polk PSW505's x 2
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post #4 of 7 Old 10-04-2012, 05:13 PM
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You can't ever go wrong getting better speakers. If you pick the right ones, they could last you 20 years, where electronics probably won't quite make it that long, and displays definitely not because technology changes. Good speakers from 1985, so long as they're still in good condition, are still good speakers. It's the one area of your system where your investment can be long term.
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post #5 of 7 Old 10-04-2012, 05:29 PM - Thread Starter
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Heya,

Hrm, so I'm curious why some people would advise me to throw on a better amplifier than what the VSX1121 already does? I'm a down to Earth kind of guy, if I'm not actually getting any real world audible difference from an amplifier beyond what the VSX1121 does, then I don't want to waste the money as I have other toys I'd love to spend that on and appreciate. A lot of them are saying that the VSX1121 is probably only actually outputting like 30~40watts per channel when using all channels (7) in extended stereo mode. And they're saying that's why a dedicated amplifier would be useful, to juice that up to higher performance. Seems weird though, why would something rated at 110 wpc only do half or less of that? Simply due to tricky advertising of specs? I actually got the VSX1121 because it had 2 sub out puts, pre-amp out for every channel, was 7.2, and had decent power rating at 110wpc at 7 channels (got it used for $400ish shipped from Amazon).

So is the whole power output thing really just a difference of audiophile myth stuff, compared to some real world folk?

Edit: I was just told that the VSX1121 only puts out 40 watts per channel at 8 ohms when all 7 channels are in use. How is this calculated or is this even true?

I would love to be able to test my M70's on a lot more power output to see if they sound different at the same perceived volume compared to my AVR to see. But all I have is weaker AVR's to see what it would sound like going from 75 watts to 110 watts basically, which doesn't seem like it would be much of a difference.

That said, when I isolate the M70's in stereo on the VSX1121, it seems like the bottom two drivers are not outputting the same as the top three drivers. I assume they are the bass woofers, which is why they're not outputting mids, as they sound more like mid-bass and lower end of mids. I'm not sure how it's wired though. I would assume it would all come from each speaker equally with the power distributed equally amongst the drivers. Any ideas how or why this is?

Very best,

Source: Pioneer VSX1121 (shopping for an amplifier(s))
Fronts: Polk Monitor 70's x 2
Center: Polk Monitor 70
Side Surrounds: Polk Monitor 50's x 2
Rear Surrounds: Polk Monitor 50's x 2
Subs: Polk PSW505's x 2
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post #6 of 7 Old 10-04-2012, 09:18 PM
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Quote:
Originally Posted by MalVeauX View Post


So is the whole power output thing really just a difference of audiophile myth stuff, compared to some real world folk?
The ability of an amp to supply power to a speaker in combination with the speaker's complex impedance and efficiency produces the maximum sound pressure level achievable at a particular distance. Maximum, not average. It's how loud you can play before distortion sets in. It's not a single number, because no speaker has a flat even impedance (load) at all frequencies. Some average 8 ohms, but dip to 4 ohms in some places. But don't obscess, the general average number do work out. In most cases, unless an amp is severely underdesigned, amps will sound identical to each other. If there are any differences at all, they'll be subtle, whereas the differences between speakers is huge, not subtle at all. Audiophiles mostly have at least a little OCD, and tend to obscess about all sorts of minutia, which is fine, but if we're being practical and trying to spend money wisely in areas that will make the most difference, it makes little sense to focus on the amp issue.
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Originally Posted by MalVeauX View Post


Edit: I was just told that the VSX1121 only puts out 40 watts per channel at 8 ohms when all 7 channels are in use. How is this calculated or is this even true?

It would be nice to see some measurements that confirm that, though as you read on it may not matter much.

I couldn't locate test data that showed power output with all channels driven, but that's not a real-world condition. 70% of everything you hear in a 5.1 (or 7.1) soundtrack comes from one channel: the center. Next are the left and right, splitting most of the remaining 30%, and only a tiny bit comes from the surrounds. You can't count the sub, of course, because it has an amp of its own.

Here's some test data on the two-channels driven condition, which while not totally realistic, is much closer to reality:
http://www.hometheater.com/content/pioneer-vsx-1021-av-receiver-ht-labs-measures

As you can see, it easily does better than 100wpc into two channels. What's unrealistic is, driving an number of channels with an exactly identical and full output signal is a condition peculiar to test signals only. It never actually happens with actual audio. Yes, being able to drive full power into all channels at once would be nice, but not really necessary.
Quote:
Originally Posted by MalVeauX View Post


I would love to be able to test my M70's on a lot more power output to see if they sound different at the same perceived volume compared to my AVR to see. But all I have is weaker AVR's to see what it would sound like going from 75 watts to 110 watts basically, which doesn't seem like it would be much of a difference.
You have to be really careful if you decide to do that. Just getting a big stereo amp and hooking it all up isn't a valid test because you KNOW you have a big amp hooked up, and you'll want to think it's better, so it will sound better. If you really want to know if it's different you have to set up a double-blind test, where you can switch from the AVR outputs to the amp outputs to compare them, then switch to a randomly selected unknown third choice, which will be one or the other, and try to match it to either the AVR or amp. That's why it's double blind. You don't know what the third choice is, and if you do multiple comparisons (you need about 15-20) where each time the third choice is randomly changed, you'll have valid data. Typically we see about 50% accuracy in these kinds of test, which is equivalent to guessing without hearing anything, in other words, the differences are not audible.

However, again, if you know what you're listening to, and probably will have the big massive and impressive looking amp on the floor in front of you, I promise you, you WILL think you hear the difference, but it won't be reality.

I'm fully prepared to hear from other posters that will say otherwise, but the scientific data isn't there. If on rare occasions amp do sound different, and can be detected reliably in a double-blind test, it's because one of them has a non-flat frequency response. But there's not too much more to it than that. You are, of course, welcome to give it a try. I have found a correlation between good industrial design and perceived sound quality. In other words, if the amp looks massive, or has a thick milled front panel, or has blue lights, green lights, red lights, or white lights, and something that moves like a meter, rounded corners rather than sharp, etc., it will sound "good" or "better" because of the additional positive sensory input it provides. Strip that all away, and you strip away the "good" sound too.
Quote:
Originally Posted by MalVeauX View Post

That said, when I isolate the M70's in stereo on the VSX1121, it seems like the bottom two drivers are not outputting the same as the top three drivers. I assume they are the bass woofers, which is why they're not outputting mids, as they sound more like mid-bass and lower end of mids. I'm not sure how it's wired though. I would assume it would all come from each speaker equally with the power distributed equally amongst the drivers. Any ideas how or why this is?
Very best,

The reason you're not hearing equal sound from all drivers most likely is that they aren't designed that way. In fact, if they were, you'd end up with a fairly odd sounding speaker. Designers have many tricks at their disposal. Controlling the level from each driver is only one thing they can do, there are lots of others, but I wouldn't expect them to all be equal. I know of a speaker that uses 3 tweeters in a stack. The middle one does all the work, the upper and lower help control the horizontal and vertical coverage of the speaker. The idea was to spread the highs out horizontally, but not vertically. But if you tried to listen to the upper or lower tweeter alone, you'd think something's wrong. That's just one example of a speaker that I'm more familiar with, but without more knowledge of how yours were designed it wouldn't be reasonable to assume anything.
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post #7 of 7 Old 10-04-2012, 09:55 PM - Thread Starter
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Heya,

Thanks for the explanation and links. Helps quite a bit. I totally get what you mean by being careful with tests. I do it with 40+ headphones and know what you mean with fancy gear making things sound better psychologically. I'm fairly realistic about it. I just don't have a discreet amplifier to test with to know with my own ears. I think at the end of the day, I just need to configure my channels and which ones are hot a little more to get the spread of sound that I like.

Very best,

Source: Pioneer VSX1121 (shopping for an amplifier(s))
Fronts: Polk Monitor 70's x 2
Center: Polk Monitor 70
Side Surrounds: Polk Monitor 50's x 2
Rear Surrounds: Polk Monitor 50's x 2
Subs: Polk PSW505's x 2
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