Need amplifier advice

[Jayell]

I have a denon x-4000 and have several speakers hooked up including my polk monitor 70's. I am wanting to put an amp behind my denon that can push my polks and free up some power to my other speakers. I was told by best buy that i need a preamp but i think they are wrong. I am just wanting to spend a few hundred, not a thousand, to get a 4 channel amp that pushes about 150 per. My questions are, do i need a preamp or regular amp? Is it just an rca out from my denon into the amp rca input to get it to work?
Also, does anyone have any suggestions on what amp to use?

 

[Jetster]

So 125 watts per channel is not enough?

 

[DeathtoGnomes]

No you dont need a pre-amp, your Denon does it all. If you really need to up your amperage, contact Denon. They might have an amplifier that you can stack and that matches up aesthetically.

 

[Jayell]

So 125 watts per channel is not enough?

Nope

 

[EarthDog]

Not sure how an amp "frees up" wattage for "other speakers" on the same receiver. Your receiver is xxxW x however many channels. You don't get more wattage taking other loads off of it.

 

[Frederik S]

Depends on how loud you want to play. 125 watts into the Polk 70 should give you plenty of volume they seem quite efficient from the specification sheet. You definitely do not need a pre-amp as that is used when you have a power amplifier.

 

[Ferrum Master]

Not sure how an amp "frees up" wattage for "other speakers" on the same receiver. Your receiver is xxxW x however many channels. You don't get more wattage taking other loads off of it.

Because those multi channel amps are all shit at most. Their limiting point is the trafo itself. Not the B class output stage. Shared current as normaly in 5.1 all speakers are not used, so it is considered and gimped.

For speakers like those 125W is not enough. They are not bad nor stellar. Needs proper pairing. Dedicated amp is a way to go...

 

[Frederik S]

The amplifier is rated at 125 W continuous operation on the two front channels into an 8 Ohm load. There should be more than enough power for the Polk speakers, unless it is a huge room and insane listening levels. You can use the pre-outs on the Denon and get a power amplifier if you want.

 

[Ferrum Master]

The amplifier is rated at 125 W continuous operation on the two front channels into an 8 Ohm load. There should be more than enough power for the Polk speakers, unless it is a huge room and insane listening levels. You can use the pre-outs on the Denon and get a power amplifier if you want.

Those speakers are 250W... you are underdriving them, thus the amp runs on max always, overheats, clips, distorts and eventually will shut down. I have to remind you that speakers and amps need to be paired. As we see the OP already cranks up his denon so a power sag occurs. And that's the main issue here.

Nobody asks you for his desired/needed power for the room size.

Dennon apples are not the same as Polk Audio also for sure. Denon weights around 12kg, minus chassis and boards and elements, it means ~ 700W trafo, AB class roughly 600W on SEVEN channels + Woofer? Hanging 500W at the front... well... too much.

OP should really answer about the real application, and why he needs more than two speakers, that would narrow out exactly what kind of amplifier he needs.

 

[EarthDog]

Thier peak INPUT wattage is 275W.

When the volume isn't turned up on the the receiver, the amp isnt using all of its output. Only when the volume is up all the way would it use 125W. Not sure where you are getting at, but this 250W ea channel thing is for the receiver when the Polk 70's are hooked up. The sub has nothing to do with the amp since it isn't a powered channel, typically. Is it here?

The OP should be able to use preamp out from the receiver assuming it has it... and i expect a $1K recover will... and get an amp. But it won't free up wattage for the other channels...at least not a noticeable amount I wouldn't imagine.

 

[Frederik S]

There is no such thing as under driving them. If you can get them to play loud enough without distortion you have enough power. 125 W into the 8 Ohm load assuming normal speaker efficiency gives you plenty of volume.

If you turn up the amplifier to max it will output 125 W into 8 Ohm, if it is too quiet get a bigger amplifier.

 

[Ferrum Master]

it will output 125 W into 8 Ohm, if it is too quiet get a bigger amplifier.

You fail to read... it is in two speaker setup @8ohm, hanging up all will almost halve the power... that's the issue and what the OP is asking around.

 

[EarthDog]

What? Where did he say that? It's 125W /ch at 8Ohm...these are front L and R channels...

Also, 150W isn't going to be much louder than 125W really anyway. Seems pointless without getting aN amp which can output more than 150W

 

[Frederik S]

There is nothing in the specification sheet that would suggest that the amplifier cannot handle 5 channels at max load under normal circumstances. From the reviews of the amplifier you can see that people are getting harder to drive speakers to be loud enough without running it at max, also in 5.1 setups.

 

[Ferrum Master]

What? Where did he say that

free up some power to my other speaker

And Denon states that 125W is at 2chan setup, it uses more it has less power... just as most AVR's does... BTW I think this AVR is capable of 9.1, it is designed to have a additional amp actually... nor that I've seen 9.1 content anywhere much lol.

And don't push him, he already told us that he needs more, no lecturing about it is enough.

So 125 watts per channel is not enough?

Nope

There is nothing in the specification sheet that would suggest that the amplifier cannot handle 5 channels at max load under normal circumstances. From the reviews of the amplifier you can see that people are getting harder to drive speakers to be loud enough without running it at max, also in 5.1 setups.

I did my simple math as you saw... in AB class amp it simply cannot be otherwise. I don't care for the tampered and subjective consumer device reviews really, imaginary friends.

Well maybe you can tell me what kind of magic can turn 670W eating from the mains(as stated on the device) running AB class + CPU/DAC/PREAMP/MSC into Six speakers running 125W? Mhm? Okay let it be... even quad setup?

 

[EarthDog]

Ferrum.. stop sitting hairs on the correct wattage and how it splits it up. You know darn well that isn't my/the point.

Clearly he needs it louder, but your points aren't making much sense to me with the "500W for the speakers" and "halving the power" etc..

Point is.. dude just needs to figure out if his receiver has preamp outs and if so, get an amp....preferably one with more than a mere 25W more than he is complaining about.

 

[Frederik S]

Is it "nope" as in not loud enough, or no as in some "hifi guy" told you you are under driving them.

The only case where using pre-outs to a power amplifier helps is if the power supply for the receiver is under dimensioned, which does not seem to be the case when looking at specifications.

 

[Ferrum Master]

some "hifi guy" told you you are under driving them.

Your denial of such thing amazes me... actually the term comes form PA segment where it is a daily occurrence, the thing he tries to do is very PA, as he seeks for power and doesn't care for else, and has nothing to do with some crapped HIFI I don't do also.

 

[Frederik S]

What does under driving do? It is not telling you anything.

If the amplifier is distorting or not producing enough power say that. Which is why is all boils down to volume. If the amplifier is distorting at his preferred volume setting then get a different amplifier.

The amplifier should drive an 8 Ohm load without distorting as it is designed for that load.

 

[Ferrum Master]

The amplifier should drive an 8 Ohm load without distorting as it is designed for that load.

Don't double post, please.

Running on 100% max for a longer period kills any device I know these days, these things are designed without a reserve. This time the OP is trying to to cut a tree with a foldable knife. Wanting to split a hair of power more? That's 125W at 1K... so at bottom 20-20K it really is some 100W per channel. No wonder someone complains.

Clipping is still a casual thing, don't you see simple LED's indicating on most PA devices? I wonder what for are those if such thing doesn't exist as under powering... really I am amazed mate, no offense, everything is fine with me, I am just not pushing my opinion as each person needs his own thing in such matter as audio, it ain't a SMPS power supply.

 

[Frederik S]

Why do you assume that he is utilizing even close to what the amplifier is capable of outputting? The 250 W input rating is a max number given by a manufacturer which the design can endure. This ensures that the drivers do not exceed their max design excursion and that the cross-over is not harmed.

You do understand that 100 W can give you more than enough volume overhead if the load is an 8 Ohm, 87 dB/W design. At a 100 W you would get 107 dB. Which should be more than enough for most people.

 

[EarthDog]

Don't double post, please.

Running on 100% max for a longer period kills any device I know these days, these things are designed without a reserve. This time the OP is trying to to cut a tree with a foldable knife. Wanting to split a hair of power more? That's 125W at 1K... so at bottom 20-20K it really is some 100W per channel. No wonder someone complains.

Clipping is still a casual thing, don't you see simple LED's indicating on most PA devices?

Who's running it at max??? What are you talking about? Your posts here have just been really nonsensical to me... sorry.

This train of misinformation simply needs to stop.

The OP simply needs to check if his receiver has a preamp out. If so, run those to a 2x150W+ (again, I encourage more) amp which takes preamp level input. Then it can be louder on his polks. The rest of the system WILL REMAIN UNCHANGED by this move.

Amd for the record, the receiver will do up to 7.1. Here is a line from the pdf:

7.1 channel + 2 channel pre-outs for additional stereo amplifier and speakers

 

[Ferrum Master]

Why do you assume that he is utilizing even close to what the amplifier is capable of outputting? The 250 W input rating is a max number given by a manufacturer which the design can endure. This ensures that the drivers do not exceed their max design excursion and that the cross-over is not harmed.

You do understand that 100 W can give you more than enough volume overhead if the load is an 8 Ohm, 87 dB/W design. At a 100 W you would get 107 dB. Which should be more than enough for most people.

Are you still trying to teach the man what he needs to do? That's the derail of this thread and that's what not the OP asks. It is not enough for him.

So again... I must repeat myself again... Denon Apples (wattage) are not the same as Polk audio... Polk actually is funny, 275W is not the rated speaker power, but recommended amplifier maximum it handles per channel, what kind of power (apples or oranges) RMS or old school sustained sinus, I cannot find any data sheet, for poor products they don't do that as they cannot sustain same quality and SPL range due to different parts. I don't believe in those specs actually, considering the complaints from the OP also.

This shitty Denon is prone to overheating as such. THIS. Also here. So running it on daily 3hour max? Yes it will die.

You understand that 100W may be okay with you. Maybe he wan't to put the music and go to work in his garage? Why are you judging, I cannot get that? It ain't some wicked church here.

Get a proper amp. Don't burn the Denon as it is an overpriced and buggy gimmick for a home theater where it actually should work fine.

Who's running it at max??? What are you talking about?

This train of misinformation simply needs to stop.

Obviously if it is not enough for him, he runs it on the eleven all the time.

 

[Mindweaver]

Guys you have given the OP a lot to think about. Let's calm down and see if the OP has any questions to any of the help that has already been given... and yes this is a warning.

 

[EarthDog]

It is not enough for him.

Truth. Frederick seems to gloss over that point... otherwise, he's spot on.

So again... I must repeat myself again... Denon Apples (wattage) are not the same as Polk audio... Polk actually is funny, 275W is not the rated speaker power, but recommended amplifier maximum it handles per channel, what kind of power (apples or oranges) RMS or old school sustained sinus, I cannot find any data sheet, for poor products they don't do that as they cannot sustain same quality and SPL range due to different parts. I don't believe in those specs actually, considering the complaints from the OP also.

Well aware the 275 value I mentioned earlier is the max for the speaker. We are also well aware that its 125W for the L and R channels. In surround, it likely breaks it down to less. Indeed. Not relevant... said that earlier...

This shitty Denon is prone to overheating as such. THIS. Also here. So running it on daily 3hour max? Yes it will die....

....Obviously if it is not enough for him, he runs it on the eleven all the time.

So, you think the OP just sits there with it cranked all the time.

I hear what you are saying, you are right... he needs an amp (as I and others mentioned)... but your information supporting it is erroneous (the 500W thing.. running it constantly "at 11"... the fact that it will change any output on the rest of the speakers in the system...etc).

Guys you have given the OP a lot to think about. Let's calm down and see if the OP has any questions to any of the help that has already been given... and yes this is a warning.

Shoot... I didn't refresh....

I digress.