Amps & power

dholmes · February 2003

I have considered getting a 2 Adcom power amp, one rated at 300 watts x 3, the other 175 watts x5 ( for rear channels). Is this going to be a mis-match in sound ? It seems to me if you set the levels the same it would not matter. Thanks

mantis · February 2003

Umm yes.If your planning on a surround sound set up,home theater....then equal power is nessary for all channels.Go outside of this and your looking for mismatched sound.....dynamic range

George Grand · February 2003

Sorry, but I beg to differ. Don't drive the lesser powered amp to clipping levels, and all should be okay.

George Grand (of the Jersey Grand's)

mantis · February 2003

Why would you want to use unequal power if you have the chance to do it right from the start???
Dolby labs and DTS recommends equal power,why not use it?

nellis8166 · February 2003

*Some speaker companies* recommend hooking up a sub via speaker level terminals, but we don't do that, do we???..hehe
I have twice the power running my mains and center as I do to my side and rear surrounds. It is properly calibrated and I have never come close to driving the smaller amp to clipping point and it sounds just fine to, no difference at all.

-N

MxStYlEpOlKmAn · February 2003

LOL! My dad must go against all the laws of audio. he runs his mains with a 300 wat 2 channel amp from yammer, and his center and surrounds with 3 - 2 channel Adcom amps at 60 wats. hmm.....wow.

Believe it or not, thos adcom's run head to head with the yammer - both amps never clip or nething, I guess its all good...no?

jcaut · February 2003

*Some speaker companies* recommend hooking up a sub via speaker level terminals, but we don't do that, do we???

Actually there's nothing wrong with that, either. It all depends on your situation. A lot of people snub the speaker-level connections simply because their reciever has a line-level "sub out" and they feel compelled to use it... It's fine if your main speaker's bass roll-off and your processor's filter frequency on the sub-output jive with each other, but often the speaker-level connections will give you more adjustment flexibility. Plus, many subs don't have an unfiltered preamp-level input.

I don't see a problem with the unequal power question. 175W x5 ought to be plenty adequate for rear channels in a HT. Do Dolby Labs and DTS recommend identical speakers all the way around? If so, how many people do THAT? I would wager, not many; And a difference in speakers would be much more audible than unequal power.

Jason

RuSsMaN · February 2003

Agreed George, Jason.

Equal power is *not* needed from front to rear.

Cheers,
Russ

mantis · February 2003

answer me this then.A couple of years ago when Pro logic was in,unequal power receiver you found all the time.Then when Dolby Digital hit the market,EVERY SINGLE receiver manufactor went equal power for all channels.Find 1 receiver today that uses unequal power???Just one.
So what your saying on this is that dynamic range means nothing.Unequal power is the way to go.....brings me to my second question....why would you want unequal power in the first place????Why?

phuz · February 2003

Why NOT?

Some reasons I can think of having unequal power are cost, physical space, and lack of importance to have equal power.

For MOST PEOPLE, having exact matching equal power isn't an issue and probably never will be. Thats a fact.

RuSsMaN · February 2003

I have an Onkyo receiver that does not use equal power on all channels. TX-SV454.

You don't *NEED* it Dan. No one said it was 'the way to go', just simply that it is a viable option.

Cheers,
Russ

faster100 · February 2003

Ok seems if we calibrate our system to equal levels how is it gonna make a difference when the fronts have 300 watts and say the backs have 150 watts, equal is equal... levels all equal are all equal right?? if your SPL meter reads 75 db for all speakers, doesn't that mean its equal?? Ok now lets not take this at if your fronts have a 50 watt max amp and the rest have 500 watts that maybe at high volumes there will be a noticable diference, But we all here i think use comparable amps, IE: 150 wpc and a 200 or 300 wpc amp, anything within a 100 watts difference or so of each other is gonna be around the same output at "normal " levels...

faster100 · February 2003

Russ, The Tx-sv line was prologic if i'm correct, they did have unequal amps, I had the tx-sv727 and it had 100x2 fronts and like 55 wpc rears, Dan states the new dolby digital receivers have equal amps

rscamer · February 2003

I run a denon 1800 with 75 watts for the center and rears and my pre outs run a 200 wpc carver for my mains this works great. I see no problem running unequal as long as the more power goes to the mains. I have run movies and music and I find it runs good with both.:)

danger boy · February 2003

I'm running the front three speaks off 125 w amps. the rears off the receiver at 70wpc sounds good to me. some day I willl match the rears to the fronts.. but I don't think i'll notice much if anything. reason being.. surrounds don't produce half as much volume as your mains or center. I will say this though.. more power from an amp will make your speakers sound better, cleaner. I did notice that on my fronts.

dholmes · February 2003

Lots of interesting reading, Thanks everyone

mantis · February 2003

Russ,
is your receiver Dobly Digital 5.1 and DTS 5.1?Is it made today?
Or is it a pro logic receiver?

Here's my final words on using unequal power.Past what Dolby labs,DTS labs and THX want you to use,I have tried this 3 times and found it to be annoying.
Here's what I had going on...

Yamaha rxv992 with a B&K st140 which is 105 x 2.
This provided better 2 channel listening but my mains sounded different then the center and rears,and when dynamic passes happened,the mains had better dynamic range compared to the built in amps in the Yamaha.Yamaha is very dynamic,but couldn't keep up with the seperate power amp rated 25 watts more.The Yamaha was rated at 80 x 5.
Pioneer Elite vsx26tx with the B&K
this setup provided the same results as the last setup did.This time it was more noticable as the Pioneer wasn't as dynamic as the yamaha at lower volumes.
Denon avr3801 with the B&K, then a Rotel rb960bx.
Both setups where the same as above.The Rotel had better dynamic's then the B&K did.When driven to louder then 80db listening levels,then Rotel went crazy,the internal Denon amps did not.This was a big difference to me.

Despite what the companies tell you to use,I have found this didn't work for me with trying to do both music and home theater with the same system and using power amps for better fedelity for 2 channel.
I feel this way,if your going to add power amps to a receiver,which I'm not a fan of anyway,then at least use a multichannel or same brand same power all the way around.Think about that for a minute.
Some of you have and are doing mis match amp power now and don't seem to mind or notice any difference.Then why have the amps if they can't perform better then the internal amps when in home theater mode?If your sound is cleaner with the power amps,wouldn't you want cleaner sound all the way around?And what about dynamic range,if amps rated 100 watts plus have the same exact dynamic range,why have the extra power?

I feel like this, equal power to all channels,timber matching or exact speakers all the way around.Same length and grade wire for the front 3,and equal length and same grade wire to the rears,all 4 of them.

RuSsMaN · February 2003

The receiver is dig-ready. I use my Panny dvd player for outboard decoding, via 5.1 rca inputs.

You don't need equal power period, I'm not going sort through every receiver made, I'm sure there are a few out there still.

Dan, I have no idea what you just said, where's your point on equal power? Take a poll, see how many people here do not have equal power front to back, and then ask those if they have 'issues'.

I don't, RonP doesn't, looks like a couple members above don't have any issues either..... Ok for these members to have an opinion, or is the pro just going to beat this one to death?

Cheers,
Russ

TroyD · February 2003

You don't NEED equal power to all channels because not all channels require the same power at the same time. Even that isn't really a player because as long as there is enough power what does it matter what the amp is rated at? If all channels HAD to be equal, what about the sub amp?

I have a Carver m0.5t (140wpc) biamping the center and a Carver m400a (201wpc, thanks Russ) powering my fronts and the rears connected to the receiver. Works just fine to me.

BDT

TroyD · February 2003

a couple more points to be considered:

Pro-logic, if I remember correctly, the rear channels were monoaural with a pretty limited range so not a lot of power was required.

Next, very few, if any DD receivers have five separate mono amps. Meaning that one channel can essentially borrow from another, why? because not every channel requires the same amount of power.

Also, how much *real* difference is there between, say 80 and 125wpc?? In reality not much.

As was pointed out before, if you aren't clipping the smallest amp, you've got no worries.

BDT

madmax · February 2003

Originally posted by TroyD
Also, how much *real* difference is there between, say 80 and 125wpc?? In reality not much.

BDT

I would go for this one. So lets say you doubled the power of the fronts vs the rears. The difference is barely perceptable. Now if you were talking 5 to 10 times difference in power then I would agree that there is a problem. In principle I think the surrounds should be the same power as the fronts, or at least pretty close. I think the center and sub should be higher power than the rest though.
madmax

TroyD · February 2003

I'd tend to disagree a little bit with that, I think it would be, in order:
Fronts
Sub
Center
Rears

Reason being is that Fronts and sub are handling most of the bass that really sucks up the juice. Just MO.

BDT

HBombToo · February 2003

I'll add that if your not clipping while hitting the reference levels your fine.

Much talk on the audible characteristics that an amp would add suggests to me that all amps should be identical. I do not buy into this but I can see how the notion would be justified.

Like I have said in the past I am not trained to be a criticle listener nor do I take it to that level.

HBomb

faster100 · February 2003

agreed Hbomb, crimminey!!! enjoy the system.. if you get all anal about speaker wire length and brand, and amp brands and wattage outputs, Buy more exspensive gear that will outshine some if the minor defects you "think" you hear, I don't keep a log but when i use wire i try and make it even, bUt christ i don't get Hbomb the Engineer to make a blue print for my wire,LOL kidding, that was a compliment henry, But really when it gets down to this and nit picking details it's no longer fun, Fun is getting what you have sounding nice, buying new gear, watching a new DVD, or listening to a new dvdA CD, Not being on your knee's with a calculator and pocket protector figureing wattages and wire lengths... Have fun i say

faster100 · February 2003

can i get a amen?? I said can i get a Amen!! Amen Amen

north51 · February 2003

I heard the amen, but I had a question about two amps.

I have heard that even if you have two amps (ex. 200wpc on the fronts, and 100 wpc on the rest), that it won't matter once they're all calibrated (to say 75dB).

In theory, if the fronts have to work less hard to give you 75dB, wouldn't that be better on your amp? For example, they say that your amp has to work twice as hard to give you a 3dB increase in volume. If this is true, does the reverse work? Does your 200 wpc amp indeed work less hard than your 100 wpc to give you the same volume?

I have heard the same argument for lower gauge wire. Your 12 gauge wire has less resistance then 14 gauge, and it should enable you to get the same volume output using less power. Again, this would be a benefit because it would be easier on your amp.

Thoughts???

HBombToo · February 2003

AMEN! and absolutely no offense taken my friend.

HBomb

HBombToo · February 2003

Originally posted by north51

I have heard the same argument for lower gauge wire. Your 12 gauge wire has less resistance then 14 gauge, and it should enable you to get the same volume output using less power. Again, this would be a benefit because it would be easier on your amp.

Thoughts???

In general you have the idea. I'll add as an example if you have very long runs using 14 guage and you sense your amp every "now and then" clipping/distorting or just struggling with peaks then you may overcome this problem if you upgrade to a 12 guage. Let me qualify this by saying this example is not an extreme case of clipping but on the very hairy edge.

+3dB is double and -3dB is half

HBomb

MxStYlEpOlKmAn · February 2003

OK....Probally been stated -- but who in their right minds put a 105 wat B&K with a 80 wat Yammer and exspect the yammer not to clip? hahahaha - i need to pick myself up off the floor with that one. thats hilarious.

TroyD · February 2003

Pick yourself up off the floor.

How much difference, MX, is the difference between 80 and 105 wpc?

Damn little.

BDT

MxStYlEpOlKmAn · February 2003

no, im looking at the amps within -- I own a yammer, and there is no way on god's earth that 80 to a B&K rated at 105 could it run head to head, the yammer would scream bloody murder and sweat like it had a kidney stone.

Amps & power

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