Just What is so Special about adding a separate amp to a high power receiver?

Discussion in 'Archived Threads 2001-2004' started by Arthur S, Apr 24, 2002.

  1. Arthur S

    Arthur S Cinematographer

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    Folks on this forum are constantly discussing adding 1 or more separate amps to their receivers. I can understand this if we are talking a 50-60 watt receiver. But with the flagships we are talking 100-125 watts per channel, in multi-channel use.

    Also, it doesn't seem to be just one brand of receiver that people are anxious to add separates amps to. Do all the high power receivers sound inferior to all separate amps? Many high power receivers can deliver more than 175 watts per channel in stereo into 4 ohms. Isn't this enough?

    Added wattage is clearly noticable when trying to drive heavy bass with inefficient speakers, but today, most of us have subwoofers. So where is the great need?

    At this point I am simply not convinced that all separate amps sound better than all receiver amps despite the frequent testimonials.

    Artie
     
  2. Deane Johnson

    Deane Johnson Supporting Actor

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  3. Shane Martin

    Shane Martin Producer

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    Arthur,
     
  4. Harold_C

    Harold_C Stunt Coordinator

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    Arthur:

    The answer to your question requires having to explain that all "watts" are not created equal. Or actually, more to the point, the currently accepted standard of measuring "watts" with a test signal into an amplifier driving a load resistors on the test bench is not a particularly good indication of how loud an amplifier will play and how good it will sound in the real world.

    What a good amplifier has to do is deliver current to a load impedance that is constantly changing with frequency. It must deliver a constantly changing amount of current, rising and falling with the musical signal. This is a very different challenge than a test signal into a load resistor.

    The keys to good amplifier design are:

    a) a large power supply

    b) the ability to deliver large amounts of current on demand, particularly on musical peaks.

    c) sufficient cooling to dissipate the heat generated by large current flow

    d) output devices that can handle large current without blowing up.

    Unfortunately, all of these things require pricy components, large heat sinks, etc. Unfortunately none of these things fit into the budget dollars available to hit a price point for a receiver.

    So, what typically happens is that the receiver amplifiers are designed to produce a number or a "spec" under the lab test conditions. They don't have the extra current capability to really be tight and punchy on music. Then, to keep from blowing up output devices, they use large amounts of a protection mechanism called "current limiting". This is specifically intended to prevent the amplifier from delivering the current necessary for a big, tight, walloping bass note or a guitar chord that jumps out of the speakers.

    This is not to say that all separate amplifiers are good. There have been plenty of weak-knee'd separate amplifiers, mostly from the same brands that build weak-knee'd receivers. Generally not as bad as receiver amplifiers, but gutless nevertheless.

    However, most of separate amps are made by companies that cater, to some degree, to a more performance oriented audience. They tend to have more robust power supplies, more robust output devices, better cooling (heat sinks are one of the most expensive parts of an amp), less current limiting, and more ability (watt for watt) to make speakers stand up and shout. A very well-designed 50 watt amplifier could run rings around the typical "100 watt" receiver channel -- louder, cleaner, better bass, more punch, better imaging, more dynamic range, you name it. Most of the receiver amps are going to sound laid back or lifeless when pushed -- because of the current limiting prevents them from putting any real ooomph into dynamic peaks.

    The mass market audio industry loves selling "watts" because it's easy. Salesmen just spout a number. Consumers think a bigger number is better, and so on and so forth. Panasonic and Sony didn't get to be the size of Panasonic and Sony by trying to explain current limiting. These companies build feature/pricepoint driven products and peddling a nice simple number like "watts" fits that bill nicely, forget that today's "100 watt receiver amp" probably has less quality component content than a 40 watt integrated amp had in 1980. I could point you to an Onkyo or Sony V-FET integrated amp from that era that would pound their top of the line "100 watt per channel" receivers silly. It's not that Sony and the others have forgotten how to build a good amplifier. It's just that they can't churn it out in a Chinese factory at a price that will sell.

    The two most important things in a system are the speakers and the amplifiers driving them. Given the choice, that's where I would put my money and live with a cheapo preamp output receiver or a cheapo DVD player.

    I recently compared my system being driven by a "100 watt per channel) Pioneer receiver (actually it's more like 80 watts per channel) and being driven by a 70 watt per channel a/d/s/ amplifier using the Pioneer's pre-outs. The better amp was a stunning night and day difference -- as it always is. The receiver amps sounded "nice". The a/d/s/ amp rocks with sound exploding out of the speakers, much more detail, much more presences, much more dramatic soundstage, etc.
     
  5. Camp

    Camp Cinematographer

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    Arthur,

    I didn't believe it would matter either. I wanted a 5-channel amp as a first step into separates. I added a relatively "low end" Sherwood Newcastle AM-9080 to my Harmon/Kardon AVR-7000 receiver (a receiver known for its excellent amp stage). I figured I'd use the amp to power the receiver until I could afford a preamp but I never expected any performance gains.

    I was so wrong.

    It's like I bought new speakers...or got new ears. The difference is night and day. I could lay adjective after adjective upon you until I sounded like a magazine ad to describe the differences. I won't do that as this isn't a review so you'll have to trust me...the difference was staggering. My wife even agrees.
     
  6. Arthur S

    Arthur S Cinematographer

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    I've been a "budding" audiophile for about 35 years. The first experience I had with a receiver that could not meet the demands of a speaker was years ago when I had Bose 901s. They came with an equalizer that added something like 15-20 db of bass boost. The harmonic distortion of the receiver was very obvious. It was painfully obvious that much more power was needed to drive those speakers. (And please don't divert this into a Bose bashing session). Over the years I have had numerous receivers and integrated amps, including Harman Kardon, Pioneer, Sony, and one of the most powerful receivers ever the Technics SA-5760. The 5760 weighed 51 pounds including a 22 pound power transformer. This stereo receiver could deliver 205 watts rms per channel into 4 ohms with both channels driven simultaneously. How did it compare to lower powered receivers? Simple, with bass turned up it could deliver very strong tight bass into speakers that could reproduce it. Other than that, not much difference. This is why I suggest that since most everyone is using subwoofers these days, people are not cranking up the bass on their receivers.
    After arranging an in-home comparison of a $1,400 Yamaha receiver, a $600 Pioneer receiver, a $1,200 Nakamichi reciver, and a $1,000 Denon, I found that there was a difference in the sound. This one had better bass, that one had more punch, another one was more natural sounding. These differences were fairly sublte but real. I went with the more natural sounding Nakamichi.
    Since I was always taken by the sight of big separate amps, I got in on a closeout of a Citation 7.1. 450 watts per channel into 4 ohms. I am presently using it with the Nakamichi as the pre/pro. When I first listened to the Citation in stereo, it sounded at least as good as the Nakamichi (120 watts into 4 ohms) and probably a tiny bit better, but no where near the differences between the receivers.
    The Citation is the only amp I have ever brought home.
    And I am not looking to find anything better.
    I would never deny that receiver amps and separates amps sound different. I have enough evidence from my receiver testing to know that amps sound different. The question is why does everyone assume that a receiver amp can not sound as good as a separate amp.
    Yes, if you can actually stay in the same room with a system playing at the 105 db reference level, you are probably going to want a separate amp that rolls off the highs so your ears don't bleed. On my Rat Shack meter 92 db is very, very loud.
    So, based on my experience with receivers and the $2,800 Citation 7.1 separate amp that was part of Madrigal, the maker of Proceed, I believe that the flagships of today may sound as good or better alone as they do with some separate amps. Of course, this does not apply to those who listen at 105 db. But if the amps in the receiver are not clipping, I think it entirely possible that one could prefer the sound of the amps in a given receiver as well or better than the sound of a given amp.
     
  7. Joe Tilley

    Joe Tilley Supporting Actor

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    I have a question? Ok I'm not quite sure what way to go about saying this but what is the differance between clipping & distortion,or are they the same thing.The reason I ask is with my set up it sounds very good up to about -30 or so depending on the source being played on my reciver.I was wondering because I have thought about getting a seperate amp in hopes of cleaning this up.I'm just not sure if it would be the reciver running ot of juce or the speakers are at their limit. If it was the recever would an external amp make that much differance?
    My current set up is Sony STR-DA5ES reciever Polk RT55i Front mains,Front surrounds,Rear surrounds,CS400i Center,& DIY 15"dayton DVC Sonosub,but the sub dosent really apply here.I've been looking into something eather from Sunfire or Cinapro but I just wonted to know what the real adavantage would be here.
    Sorry I'm not tryen to take over anyones thread just thought that wile you were on the subject I'd ask.
    Thanks[​IMG]
     
  8. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

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    IMHO receiver sound lies somewhere between crap (muddy, flabby bass, poor sound staging, unlistenable at low volumes) and sub-optimal, even when including flagships like the Denon 5800. Let's assume it takes a hundred pounds of mostly heat sink and transformer to get an acceptable 100W out of seven channels using reasonable bias current (if there are real audible differences, I expect this is where they are rather than at maximum output which most people shouldn't reach) to prevent low level cross-over distortion and provide the same power when transient peaks hit all channels at the same time. In comparison, how well will 170W in a 60 pound box work?.

    Conversely, receivers plus power amplifers with a heftier weight total usually seem to suck less, and separates may be

    great.

    Of course, I wouldn't buy a receiver so I don't know what they sound like in my home, the shops selling them don't loan them out at no charge for a weekend, speaker placement in the "affordable" rooms at my favorite high-end shop's receiver room is sub-optimal, speaker placement in Sound Track's receiver-driven expensive room is sub-optimal, and most people place for aesthetics rather than performance so the comparison's I've made were most definately not apples-to-apples.

    OTOH, my old Adcom tuner/pre has sucked in single-blind comparisons while the Marantz 7C, Lexicon DC-1, etc were good so the all-in-one-box does seem sub-optimal in practice and on-paper they fail to live up to their specs more often than over-built separates. Of course, the cable swapper/level matcher may influence the listener in these tests.

    It may also be based on perception and not Truth because we haven't done double blind comparisons.

    OTOH, if you pereceive it to be true does it matter? Especially when a used Lexicon and stack-o-power-amps costs about the same as a "flag ship" receiver?

    (I don't believe in cables, am unconvinced about the differences between "acceptable" solid state power amplifiers, but won't consider any receiver but a "flag ship" in the "acceptable" category based on how intelligible things are at low volumes and feel those are still in the "sub-optimal" category for more tenous experiences. Shops which can't/won't perform A/B switching using the same speakers haven't done anything to change this for better or worse).

    To summarize, it's a religious thing based on how much hearing we retain (I can still hear out past 19KHz), what we are trained to perceive (school bands, other live music), perception colored by the placebo effect, pseudo-science, the ocassional measurement that may or may not be noticeable, etc. You really need to come to your own descision, which will lie somewhere betweeen "and the reason I'd waste my money is..." and "night and day difference...".

    Any decent high-end shop will loan you equipment for the weekend, where you can evaluate it with your (presumably as near to optimal as patience and SAF allow) optimally set-up speakers in a level-matched, single-blind environment.

    Or you can buy used and resell for close to the purchase price if it doesn't work out.

    YMMV. Really.

    A good receiver should be possible (I'm an engineer and see nothing wrong with this idea), although would the market be there? "Audiophiles" (the word has negative connotations) will buy new or used equipment with list prices totalling several times as much so placating them doesn't matter. Keeping it affordable for the masses may lead them to buy it over something with less profit margin.

    The lack of real answers here is anoying, although one can understand reluctance amongst magazines like Stereophile to publish the results of real comparisons (lost advertising revenue) especially after the cable fiasco (real blind speaker wire comparisons, sufficient gauge zip cord won over smaller exotics and the larger ones couldn't be differentiated).

    In the results out there, the emphasis is also on average tests which aren't releveant to you if you hear better. If one of 20 reviews has a statistically probable chance (this is beyond the 99% and change certainty) of having noticed a real difference in the tests, you might. OTOH, if no one in hundreds did you'll probably experience the same.
     
  9. Carl Johnson

    Carl Johnson Cinematographer
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    One of the amps in my H/K avr75 receiver, a 5.1 unit that's about five years old is dying. 5.1 sound plays as it should but in stereo mode only one channel will play. Based on the info in this thread I'm considering buying a seperate five channel amp and pairing it with the preamp section of my current receiver. Would that potentially bring better sound quality than starting from scratch with a new integrated receiver?
     
  10. Aslam Imran

    Aslam Imran Second Unit

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    I have a feeling that this thread will end up in a DBT debacle.
     
  11. Cees Alons

    Cees Alons Moderator
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    Joe,
    Distortion and clipping aren't necessarily the same things. In fact, clipping is one kind of distortion, but there are also other types of distortion present in certain amplifiers.
    Distortion is the amount of difference between the shape of the input signal and the output signal (input signal is generally voltage, output signal is voltage as well as current in endstages). One important source of distortion is when the amplifier can no longer "follow" the input signal at larger voltages (or can no longer deliver the related current): clipping.
    Two other important forms of distortion are: base line non-linearity (the amplification of the amp at lower voltages is not equal to the amplification at larger amplitudos) and assymetry: amplification in one direction of the signal is not equal to the amplification in the other direction.
    If you think about it: distortion is in fact always the same as non-linear amplification.
    To answer your other question: to find out if your suspicion is right, find a dealer who allows you to try a nice amp (you had yourself demoed in the shop first) at your home for, say, a week. That way you can find out if it's the amps in the receiver, or the speakers (or both), or something else.
    It's rather dangerous ( [​IMG] )to try and give you any decent advice from here, given the available information.
    Cees
     
  12. Chris Demaree

    Chris Demaree Stunt Coordinator

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    I recently upgraded to a seperate amp (Parasound 855) and used my Outlaw 1050 as a pre/pro. I noticed a HUGE improvement in imaging and detail. I didn't expect much of a audible difference (bought the amp in preperation for the Outlaw 950), but I can honestly say that it made a substantial difference in imaging and detail.
     
  13. Joseph_Mikhail

    Joseph_Mikhail Stunt Coordinator

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    I just got my HK PA4000 today. Its powering my mains and center. Huge improvement. So much more detail. Really opens up the soundstage.
     
  14. Steven Hen

    Steven Hen Stunt Coordinator

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    Chris D,

    We must be on the same wavelength or something! I also just added the Parasound 855 to my Outlaw 1050 in preparation for the 950. I agree, it does make a difference. I'm not that good at translating to words what my ears hear but better detail is a good way to put it. I've only been on the 950 waiting list for 1 week so it probably will be awhile. I'm so tempted to pick up the Rotel 1066 now, not sure if I'm going to be strong enough to wait for my number to come up with the 950!
     

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