Admin help me choose an amp

[zandern]

I have asked this question before but no one really answers me. What size amp do I get for my RF-3II's and RC-3II. Currently I have a Denon 2802 receiver. Do I want a amplifier with 200 watts by 3 channels? More, Less, I have no clue?!?!

[leok]

I suggest you stay under 20 Watts / chan. More than that will simply damage your ears and add distortion and noise. Personally, I've never used over about 6 watts, but my speakers are 99bD and 102dB efficiency. Most important is low distortion at low power, and for that I would look for ss class A or tube. Most inexpensve ss amps are ss push pull and they are a disaster at low power (read high distortion = harsh).

leok

[lynnm]

I'm with leok on this one.

The RF 3 II will put out 110 db at 16 watts. That corresponds to a symphony orchestra at full crescendo. I run a pair of KLF30's with a 30watt/channel tube amp and can rattle my windows anytime the noise bylaws permit.

As pointed out above the quality of the power supplied to the speakers is far more important than the sheer quantity. That 1st watt is the most important.

[maxg]

I've said it before and I will say it again. The RF3 is the most forgiving Klipsch speaker there is when it comes to amplification.

I have heard this speaker being driven by amps ranging from a 1970's 20 wpc SS Marantz through a pair of push pull tube 45 wpc monoblocks, an Accuphase E211 integrated amp, a Yamaha A1 receiver, a Sharp all digital amp and a Rotel 1080 200 wpc power amp.

Whilst there were differences in the sound they all sounded perfectly reasonable and they all went way too loud for my tastes.

With the tubes (mine) they went so loud that I had to listen in the Garden with the volume on half way.

In answer to your question you do not need 200 wpc.

[TBrennan]

Depends on how loud you want to get and how much headroom you want to handle peaks. A pair of 8" woofs are gonna start compressing at over 100db, it does not follow that 16 watts will give 110db. Mind that peaks really eat-up power. The other day I observed my bass amp hitting over 10 watts, that's driving a horn-loaded Altec A-5 bassbin of about 106db efficiency. If your Denon gives you enough volume and dynamics for your taste then use an amp with similar power, if not use more. If you find an amp with 200 wpc that you like the sound of of use it.

In any case do some listening with different amps and your speakers, Hell, nobody here knows what you like. :-)

www.chicagohornspeakerclub.org

[zandern]

20 watt amp!! Ok I thought I knew little about amps, but now I am totally confused. My denon puts out 90 wpc. I called denon and that is continuous power. So why would I want to buy a 20 watt amp?!?! About a month ago I borrowed a 50 watt adcom amp (older) and I could notice a difference with it hooked up to one or both speakers, so I figured If I want more bass at a lower volume that I would need a bigger amp. So if someone could straighten me out that would help alot. Also how do you guys know how many watts your putting out at a specific time and the db? Do you have to stand there with a meter and read it?

Sincerley, Lost

[Ray Garrison]

Zandern,

Why are you thinking about getting a different amp? The answer to that question will steer the recommendations you get.

Here are some of the possible reasons I could think of. If you could give us an idea of why you're looking for a new amp, it would help us make some intelligent suggestions.

Zandern: "Hi. I would like to buy a new amp. I am using a Denon 2802 that puts out 90 watts per channel. I am thinking about a new amp because..."

a) "... I can't play music loudly enough with my Denon without the sound becoming conjested and harsh."

"... I would like tighter, deeper bass than I am getting. I've heard these speakers put out more bass, so I think it's my Denon that's limiting the bass I'm getting."

c) "... I think I can get better imaging and more accurate tone than I'm getting."

d) "... I just don't like the sound with the Denon. It plays loud enough and all, but the music is just not very involving."

e) "... I have way more power than I need - I barely turn up the Denon. I think I would get better sound with a higher quality, lower power amp."

f) "... "

Don't just say "all of the above" - seriously, what is it that you are looking to improve?

Ray

[lynnm]

Well it would seem to me that if your Denon can put out 90 w/channel then it has plenty of power for your RF 3's!

The suggestion regarding a 20 watt amp was merely to suggest that a clean 20 watter is adequate power and was not presented as a maximum rating.

As far as the differences you heard between the 2 amps - that is obviously related to the sonic character of the amplifiers being tested. This should serve to illustrate that you cannot rely on specifications to tell you how any amplifier is going to sound with any given set of speakers - or in any given room for that matter.

The figures I quoted for sound pressure vs. power input is based on the mathematics of sound output:

To double the Sounnd level produced by a speaker at a measured distance and frequency requires a doubling of input power. It gets a little confusing because a doubling of aucoustic power from some reference loudness is represented by the value +3db,(correspondingly a halving of acoustic output is described as being -3 db).

The RF3 II is rated as having a sensitivity of 98db/1watt/1 meter. In other words a sound pressure meter placed on axis 1 meter,(39") away from the speaker will display an SPL of 98db when the speaker is fed with a 1 watt signal at a frequency of 1 Khz. To double the out to 101db. under the same circumstances will require 2 watts and so on.

I don't have an SPL meter and therefore not tell how much output is being produced in my room at any given moment, although when I had an amp sporting power meters the reading rarely exceeded 10 watts. Bear in mind also that laboratory measurements are taken while feeding the speaker with a single frequency while music consists of very complex waveforms whose frequency will vary between 20 hz. and 20000 hz. Remember also that the readings from power meters etc. are not especially accurate as the meter movement cannot really accurately keep up with the fluctuations in power drawn by the speaker from the amplifier.

Sensitivity ratings then can at best be taken as a reference point by the vast majority of end users regarding how much amplifier power is needed to get optimal performance from a speaker. Many highly regarded speakers are rated at 89db. If you understand how those ratings work then the math will tell you that your 98db. speakers will produce about 6 times as loud an output at 1 watt in as the 89 db. speaker. The lower efficiency speaker will therefore require considerably more power than the higher efficiency units.

The above should not be taken to mean that higher efficiency speakers are by definition superior to lower efficiency speakers however. In my time I have listened to high efficiency speakers that sound awful and low efficiency speakers that sound very nice indeed.

[Deang]

Ray, as always - pegs it.

We need more info.

Budget limitations, as well as how big your room is, and how far away you sit -- would be nice too.

Since you have a center channel, it sounds like you are building a multi-channel system -- which really makes a difference as well.

As far as the power thing goes, I'm with Tom on this. Just because you have 200 watts doesn't mean you are going to be pushing 200 watts and blowing out your ears. The additional power will give you more headroom and extension during peaks -- and this is not a bad thing to have -- especially for HT.

I'm doing 35 watts with RF7's, which is just right for me -- as I do plenty of movies. I say with the RF3's, you should be fine with the 90 watts you have. So, enter Ray's post -- what are you looking for?

I just checked out the Denon 2802, and it looks really well made.

Maybe what you should really do is find something to replace that Aiwa:)

[sunnysal]

Ray is right...unless you aren't getting the volume you want from the existing rig I would not even consider changing amps, that receiver is quite good in fact. If you are unsatisfied with the quality of the sound that would be another story, let us know what you are trying to accomplish by swapping amp and we can be of more help. regards, tony

[zandern]

I just want more bass for when I play my music. I want the bass to punch me more. With my Infinity 250 watt 12" downfiring sub I get room shaking bass, but not the bass that you feel in your chest as much. As for the room, I move alot so the dimensions will change, but typically the room will have an 8 foot ceiling, and be oh lets say 15 X 15 or so, but one side of the room is open to the rest of the house.

Thanks for all the input already. I am learning and I am also finding out that I might not want to do this and have to replace my denon. I love the denon sound, just wanted more bass. Maybe I should just buy a second sub. Don't know, I just know that it seems like all these awesome HT have all these components and amps so I wanted to build my own.

[Deang]

To get the kind of bass you are describing then you are going to have to go into K-horn, or dual SVS-Ultra territory. No short-cuts here. You want your chest thumped, then you are going to need to move LOTS of air.

You could also do what some here have done. Instead of using a sub, use a pro type bass bin with four 12's or 15's and a plate amp. Run that with your RF3's and you'll be stroking -- or have a stroke, I'm not sure which:)

[sunnysal]

to make maximum thumpy bass make sure you turn up the bass tone control on the denon, have selected "large speakers" for all speakers in the setup and finally raise the crossover frequency and turn up the volume on the power subwoofer...this will maximize thump, though sound quality will not be optimized. it sounds like you want impact more than clarity...regards, tony

[zandern]

Ya I don't have the bass tone up all the way or the sub set to full power because like you said I don't want to lose of the clarity. I think more powerful subs is the way to go. Someday, (after college) I want the sunfire signature sub, that should help me get that stroke. Thanks for all the inputs.

[leok]

Hello zandern,

Your questions about power and reminded me of the connection between thin sound and distortion.

Distortion generally adds frequency related (harmonic and inter-modulation) material to the normal audio program material. It adds a lot of it in the mid and upper frequencies. This makes the bass sound weak because the combination of normal and added highs overwhelm it. As distortion is reduced, bass sounds louder because there is less junk in the higher ranges. High distortion systems sound harsh and thin .. little bass. Low distortion systems sound full with plenty of bass.

This is a simplification, but I believe it is correct as far as it goes.

Also, power only helps if you are using it. If you're drawing 1 watt from a 100 watt amp and 1 watt from a 6 watt amp, and the distortion is the same for both amps AT 1 WATT, then they will sound the same. The problem is, at 1 watt, a 6 watt tube or transistor class A amp is probably producing substantially less distortion than a 100 watt transistor pp amp at 1 watt. The 100 watt amp may be great a 90 or 100 watts, but that's not going to do you much good with a set of Klipsch speakers.

This is very general, but may help. I don't think it is misleading.

leok

[Strabo]

Been a lurker for a while, but had to finally add my 2cents.

These have all been great suggestions but missing the amps frequency response metric. I had the Denon 4802 for three months this summer, and decided to upgrade to something else. The 4802 was bright, plain and simple. This gave the impression that it lacked bass. In reality it did have less bass than it had mid and upper frequency output.

Power itself isn't as much of a concern, as said by many others here. My suggestion is to listen to a few different amps and find the one that sounds the best to you. Listen to them for hours even and bring music with you that you are used to hearing.

[mobile homeless]

I kind of disagree here in that I think all 90w amps are not created equal. Listen, speaker size and sensitivity notwithstanding, I have never heard a receiver, even of Denon's level, really put out high quality bass in the same category as an excellent amplifier with a top notch power supply and circuit. Basically, in a multi-channel receiver of this nature, Denon or not, you are going to get a compromised LOW END as well as compromised sonics all the way around, this relating to music, not HT. You basically have ONE BOX with a power supply now deligated to tuner, preamp, and MULTI-AMP duties. This power supply, one of the KEYS to bass, is spread around too much and is not even of a high quality to begin with. You are asking it to do service for MULTIPLE amps on top of preamp duties. As I said, you are just not going to get the quality low end you would get in a well-designed two channel amplifier with a dedicated stiff power supply(or better quality mulitchannel dedicated amp).

I have heard a plethora of AV multichannel receivers in this range and have never been satisfied with the sonics with anything but movies. And with movies, it seems a better dedicated amp with a high quality subwoofer does very well. Granted, a sub upgrade might be needed but to get the most out of your system for music, better quality amplification is needed. I am a big tube proponent, especially for music, but there is good solid state. Perhaps you can get chest thumping bass with mediocre electronics but it wont be of quality.

...And more watts is not always the answer.

kh

systems

[prodj101]

I say get more than 20 watts as stated in previous posts. I have had my SF-2's up there before. I just couldn't stand not being able to drive them at dance hall levels, and a 5 watt p/c amp simply won't be able to do that.

[Jolly Roger]

I think it depends on what you plan on doing with this amp personally. You asked about a three channel amp so I assume you plan on using it in conjunction with the rear amp channels in your denon.(for ht) If this is the case, you would have been better asking this in the home theater forum. People in here are a little too pro-tube. Sure you don't need alot of "watts" to power the rf-3's. Power in watts is not really a true example of how well a amp handles a load either. To say you only need x number amount of watts is kinda stupid imo. Its about design and sound. For example, my B&K 7250 is rated at 200 watts x 5 vs the amps in my Denon avr-3300 105 x 5 which was a respectable $1000 dollar reciever when I bought it. I think there is a huge difference. I do still use the denon pre also I might add. The amps in the denon sound way more bright. The B&k is much warmer with much better seperation. Do I use any more "watts" in one amp than the other? NO. The B&K is just a better design. Talk about transformer? This thing is huge. Break your freakin back to try and lift. I personally wouldn't try and mate three 20-30 watt tube amps with the ss amps in the 2802 but thats just me. Also, I'm from the camp thats its far easier to damage speakers with an under-powered amp than over. As stated, more than 16-32 watts into these speakers would be probably too much even though they are rated at 150 watts. So as far as clean power, these speakers can take it. Over-drive a low powered amp will blow speakers in no time. You know how when you turn your 2802 up really loud and it starts to sound not so good? Thats the amps dying not the speakers. (or amps killing the speakers either way) The thing is, tube amps don't have this problem or at least as bad. Something to do with even/odd order harmonics being produced. So 20 watts means pretty much 20 watts in tube power and this is why we never see 20 watt solid state amps. Anyway, there are alot of options. I would look more toward more quality products, than more or less powerful ones. This board is full of people that are into low powered tube amps and very efficient speakers. Especially the two channel forum. Keep in mind your getting that type of biased response when you ask questions here. JR

[dougdrake]

Not that I can add any credibility to mobile's post, but I found what he describes to be true in my setup. I was using a Denon 3300 (105x5) driving my Forte and Chorus speakers. Sounded nice, and the bass was certainly there. Then, I added an Acurus 200x3 (which by itself weighs much more than the Denon does - buying amplifiers by the pound!!) and the bass seemed to come alive. Not that I was using that much more power, it was just better power.

So now my 3300 acts as a preamp for the system, and as an amp for the rear channels (for now).

DD