Axiom Home Page Forums General Discussion Home Theater Thinking about getting amp for fronts

I've used many receivers for Home Theater - a Harman Kardon AVR 65, an Onkyo TS DX797 THX for 7.1 channel HT and DVD Audio, a Sony STRDB1070 for 5.1. I've also used the big Onkyo and Sony as processors with outboard amplification. I heard a big difference. The issue is not whether an Onkyo 797 or Sony STRDB 1070 will push Axioms to high SPLs, the issue is how good does it sound. My Onkyo 797 sounded better with outboard amplification than it did using its internal amplifiers. I used an Onkyo M-504 2 channel for the front L/R speakers and an Anthem PVA-5 for the rest. I don't know whether or not the outboard amps would play louder than the internal amps, but they sure sounded much better. I used 3 Onkyo M282 2 channel amps with the Sony, and that set-up certainly sounded much better than the Sony's internal amps.

I have a really nice 2 channel system in my garage - a Kenwood KA9100 with twin power meters, and a pair of Dahlquist DQM905s. I was listening to some nice jazz at pretty high levels and noticed that the Kenwood's power meters rarely bumped past 3 watts and most of the time the amp was putting out under 1 watt!

Now, for HT (and symphonic pieces) you need head room - amps which have the power reserves to handle sudden transients to high levels, booms, bangs, roars ... or the cannons from the 1812 Symphony ... that means you need more than 3 watts per channel. So, if most of the material we listen to does not require more than (let's go crazy) 5 watts per channel, what can be the difference between the internal amps in our receivers and dedicated outboard high power amps? More ... the Anthem PVA-5 puts out 120 watts per channel - pretty much the same as the rating for the internal amps in the Onkyo 797. So, if it's not the number of watts, what's the difference between the internal amps and dedicated outboard amps?

There's a saying - if the first watt isn't any good who cares how many more like it are lined up behind it? If you believe there is no difference between amps of similar output, then don't bother getting outboard dedicated amplification.

I tested the proposition using my ears - and upgraded my HT systems by using the receivers as processors with outboard amps. I've since sold my receivers and picked up dedicated processors - an Integra DTC 9.4 for the 7.2 system, and a fabulous Sony TA E9000ES for my 5.2 system. (I've since passed the Onkyo M282s along, and replaced them with 3 Yamaha M80s). Do I hear a difference? You betcha! Do I play my movies or music any louder? I do not! Do these systems sound better than with internal amplification? Absolutely they do! Do I know exactly why? No.

2x6spds, you nailed it man!

I agree with 2x6 and Minirock.
I used to run receivers like Rotels flagship RSX1065 receiver and the Pioneer 53TX. Both handled HT and music great. But when I went with external amps through the preouts of the above receivers using Bryston 4B,3B and 2B amps and my current Musical Fidelity A300, my music and HT sounded much better. Without telling my fiancee that I switched out the receiver and put in power amps she noticed a big difference in dynamics and extra information. Many people that have come and demo my system also have mentioned the increase of sound quality at the same level of output. Today I have pulled out the receiver altogether and run the power amps from the sound card of my HTPC which does 7.1 output to my power amp and to the projector.

In reply to:

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booms, bangs, roars ... or the cannons from the 1812 Symphony

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Keep in mind that the aspect of audio that requires the most power -- bass -- is frequently offloaded to powered subwoofers.

I agree that many A/V receivers wouldn't be able to properly drive a pair speakers to cleanly reproduce the cannon fire found in the 1812 overture without the ability to offload much of the duty to the outboard amp in the subwoofer.

I've actually used the Rotel RSX 1065 before. Great piece by itself and an excellent preamp when paired with good amps. "Increase in sound quality at the same level of output," is the perfect way to describe the advantage of using an external amp. Smooth/ warmer midrange, crystal highs, better low end if you are running your speakers full range, and less chance of otic fatigue which plagues entry level to moderate priced (all but the best) receivers.

I hesitate to ask, but what is "otic fatigue?"

ot is a Greek word root meaning ear; otic is the term that means pertaining to the ear. Otic fatigue can relate to both the auris sinistra and auris dextra (both ears). I guess you could also call it audio fatigue.

Luis, I'm sure that your comments are well-intentioned, but those factors that you describe simply don't exist. Competently designed amps operated within their power limits are transparent. There would have to be major measurable differences in frequency response or distortion for such audible differences to exist. Such measurable differences don't exist and any audible differences claimed disappear when the listener is forced to trust only his ears in a blind listening test.

I'm thinking you guys are going to have to agree to disagree on this subject.

This sounds like another one of those subjects nobody should post about without a beer in hand.

My own experience is that having a good power amp (high quality, heavy, 150+ WPC) does make a difference but (a) I have no idea why that is, and (b) amps in high end receivers seem to have gotten a lot better in the last 5-ish years so maybe that isn't true any more.

My personal theory is that being able to watch the power meters adds another sensory input and makes the sound SEEM better