Do all solid state amps sound the same?

[marc mc]

Marc, please note that I'm not saying you haven't heard or aren't hearing a difference, massive or otherwise. I'm only pointing out that your logic for why you're hearing it doesn't really make sense, technically speaking. A single, high efficiency driver will still have artifacts that will make a difference with some amps.

The fact that you're not hearing any difference simply means that your system is not of high enough resolution or your ears are simply not good enough. Sorry, just had to put that in there for the subjectivist crowd.

I can't say why you're not hearing a difference in amps in your setup when you do hear differences in those same amps in another setup with passive crossovers, but I can say that I doubt it's because of the loading of the amps. That will be a factor no matter what scheme you use to drive them.

Ray, your over simplifying my statements. First I understand their is more involved. Like active effectivley gives 3 db of gain which is near doubling of an amps output, it only asks the amp to play a slice of the frequencies and eliminates the variety of problems that a crossover presents to an amp. To name a few.

You might think I'm over stretching with the simple point but the outcome for me is active turned out (by accident) to be the solution for almost every problem I was trying to solve when I discovered it.

To even have to defend the advantages of active is rediculous. Ray your the speaker geeker, all the electronics engineers I know agree that active is by far the best way to go if its an option. I have said it several times that if the entire signal that I run with either of my big active set ups could be instantly switched to run through a single amp and a passive crossover at the levels I now routinely play my systems at. The amp and most of the drivers would instantly blow up. And while you know or need to know the technical reasons for that happening. I don't. all I have ever claimed is to be very good at is knowing the difference between what sounds fantastic, what sounds the same and what sounds like $hit.

marc mc

 

[whoaru99]

The point is that if we understand what truly makes one amp different from another, we become better consumers and can spend our money where it matters most.

For example, if a more expensive amplifier has a big honking power supply that allows it to double its power output at four ohms, then it is going to be better with my four ohm speakers than a cheaper amp that doesn't double its power even though they have the same power rating at eight ohms. For my eight ohm speakers the cheaper amp might be a better purchase which leaves me more money that I can spend on the most important upgrade: recorded music.

I look at it a bit differently, "backwards" so to speak.

If one chooses the amp based on worst case load/highest need, then for an amp to "half-up" is really a moot point because every one will do that.

For example, if I need/want 500wpc at 4 ohms, why do I care if the amp does 250wpc @ 8 ohms or 350wpc @ 8 ohms? From what I gathered, most amps that appear to double down merely have sandbagged readings at the higher impedances to create that appearance. Afaik, the only way to create an amp that truly doubles down without having to pad down the higher impedance powers is to have one with a regulated power supply, which then precludes any dynamic headroom because the rail voltages don't vary.

 

[Jon_Logan]

With regards to doubling down or not to double down.

This "change in output capability" is only a max output level difference, in most cases. It is usually caused by by the power supply sagging and unable to maintain a constant rail voltage and through the IR losses across the output transistors and emmiter resistors.

Under normal to loud listening levels, the output voltage is load invariant. There are/were some poorly designed VI limiters that "kicked in" too early, but those days are pretty long gone. What is available are amps that have too little protection and allow themselves to blow themselves up because VI limiting is not present, or ineffective, making them leave their SOA's.

So, I wouldn't think you're missing any thing with an amp that doesn't double down. You can calculate the dB difference and you'll find (I think) that the difference is small and that it really doesn't mean anything unless you listen to constant tones at clipping.

 

[marc mc]

I use an 80 and two 70 watt amps on one system and at levels that none of my passives could even attempt with Bryston 4b's it's yawning. I have clearly been moving down the power scale with actives.

marc mc

 

[marc mc]

I can't say for sure why you're not hearing a difference in amps in your setup when you do hear differences in those same amps in another setup with passive crossovers, but I can say that I doubt it's because of the loading of the amps. That will be a factor no matter what scheme you use to drive them.

How about the fact that the each amp is only being asked to amplify the frequencies the speaker its directly connected to needs? I mean lets face it even with three 80 watt amps running active results in basically twice the power and a third of the load for each amp.

There is a speaker maker up here that uses a 80 watt Bryston 2B's for the bass cabs and 2 300b set amps for the mid and tweeter. This guy has done a few interviews about actives and is the first guy that has written anything that I can say has been my active experience as well.

http://www.aurumacoustics.com/crossover.html

Ray this is one point I was making:
"passive crossovers, especially in three-way designs similar to the Integris, consist of large complex filters that present difficult and wide-ranging impedance loads that can challenge many amplifiers. Complex passive crossovers also create a degree of separation or decoupling between the amplifier and driver in terms of control. Across much of the bandwidth, the amplifier is interacting with the crossover far more than with the loudspeaker's drive units. Without reactive crossover components, the largely resistive loads of the drivers are optimal for signal transfer and stable amplifier performance. "



marc mc

 

[RayW]

I agree with pretty much all of that. My only point is that a single speaker can present a difficult load too. That's all.

The decoupling of the driver from the amp via a crossover is a big part, IMO. The fact that the amp is interacting with the crossover more than each individual driver is also very important. The amp only driving a portion of the audio spectrum will also be a major factor as IM distortion will be greatly reduced.

I don't think the loading of the amp is nearly as big an issue. A well designed passive crossover will result in an impedance curve that may be easier to drive than many single drivers.

 

[spl225]

Alot of folks who are into vintage audio have 70's recievers they love because of looks and also because they say those recievers sound "warm" and "full" in comparison to current recievers. Isn't that proof enough :drool: for the sake of this thread that all amplifiers don't sound the same?
Some folks believe that all things being equal, things that measure the same should sound the same. Maybe in theory, but in reality, not necessarily so. As with loudspeakers, different quality parts, build quality, and technology in amplifiers yields different results. A pair of 70's Sansui or Pioneer speakers might have been measured the same as a pair of Magicos or Hansens, but all else being equal, they sure don't sound the same . Measurements don't tell the whole story.

 

[RayW]

A pair of 70's Sansui or Pioneer speakers might have been measured the same as a pair of Magicos or Hansens,

Let me know when you find those.

 

[Jon_Logan]

Alot of folks who are into vintage audio have 70's recievers they love because of looks and also because they say those recievers sound "warm" and "full" in comparison to current recievers. Isn't that proof enough :drool: for the sake of this thread that all amplifiers don't sound the same?

I don't believe that is proof, no. Impressions based based on poor test methodology is far from evidence needed to claim a fact.

Some folks believe that all things being equal, things that measure the same should sound the same. Maybe in theory, but in reality, not necessarily so. As with loudspeakers, different quality parts, build quality, and technology in amplifiers yields different results. A pair of 70's Sansui or Pioneer speakers might have been measured the same as a pair of Magicos or Hansens, but all else being equal, they sure don't sound the same . Measurements don't tell the whole story.

The quality of measurements we have for electronics is far better than any acoustic measurement techniques or methodologies. Even with current acoustic measuring methodologies, large differences are seen between speakers. No two measure the same. The resolution and array of measurements for electronics are such that if it measures the same, it will sound the same, in a carefully performed test. Speakers are different. Speaker performance varies widely from model to model and even speaker to speaker within the same speaker model. The distortions in speaker performance are magnitudes larger than the distortions found in electronics. Please don't say that people that don't find a difference in solid state amps (the topic here), think that there's no differences amongst speakers. That is not the case. I believe that most, if not all people believe there's a difference amongst loudspeakers. I certainly do, and recommend that that is where there the greatest attention should be given.

 

[whoaru99]

How about the fact that the each amp is only being asked to amplify the frequencies the speaker its directly connected to needs? I mean lets face it even with three 80 watt amps running active results in basically twice the power and a third of the load for each amp.

I'm partially following you here....an easier load for the amp, maybe, but 80w is still 80w if you push the amp that hard, and I doubt all that from the other two (assuming one is your woofer amp) is going into the mids or tweeters if you're connected directly to them...unless all the drivers are equal sensitivity and can handle that much power. Of course, things aren't run wide open all the time, but heavy load seems to be the main mitigating factor so I approach from that point.

As well, some depends on where the frequencies are split and too even the type of music affects the distribution.

 

[whoaru99]

I don't believe that is proof, no. Impressions based based on poor test methodology is far from evidence needed to claim a fact.

Further, to this point, stating one's opinion vs. professing as fact are two completely different things. It's fairly normal (or common), it seems, in audio discussions to present one's opinion as if it were fact. I am not a believer of perception = reality derived from what seem to be in some cases a solipsistic viewpoint.

 

[marc mc]

Further, to this point, stating one's opinion vs. professing as fact are two completely different things. It's fairly normal (or common), it seems, in audio discussions to present one's opinion as if it were fact. I am not a believer of perception = reality derived from what seem to be in some cases a solipsistic viewpoint.

I agree with this point. Thats why I use as a rule my son as a soundboard. He has proven to have a fantastic ear for good sound. If I make a change of any form I sit him down for a listen without a word about what I did to see if he can hear it. He has never been wrong.

The other tool I use is 2 audiophiles that are nearby that have heard everything over the years. I lend them a piece or have them over for a listen. Both these guys tell it like it is, right to your face. I actually set up one of my active systems at both of their places and left it without a word. They both thought it was fantastic.

marc mc

 

[marc mc]

I'm partially following you here....an easier load for the amp, maybe, but 80w is still 80w if you push the amp that hard, and I doubt all that from the other two (assuming one is your woofer amp) is going into the mids or tweeters if you're connected directly to them...unless all the drivers are equal sensitivity and can handle that much power. Of course, things aren't run wide open all the time, but heavy load seems to be the main mitigating factor so I approach from that point.

As well, some depends on where the frequencies are split and too even the type of music affects the distribution.

IMO its the linearity of the top 2 amps that are freed from the bass work that makes this worthwhile regardless of the reasons. We could yatter about the why's forever but I care about the what. Don't tell me about your pudding! Bring me a bowl.

I am about action. If I hear a guy say "I did this and it sounded better" I give it a try. I have a friend that has some of the best gear I know of. I was talking to him last night and he was asking about the active stuff he knows I putter around with. He interupted me a some point and said I'm going to do it, I'm going to go buy an active crossover and try it. We need more of that. And I miss the days when we had the stores to settle all these debates in. I can assure you the active debate would be over in one song. And all the "why's" would mean squat to everyones ears.

marc mc

 

[Will S.]

With regards to doubling down or not to double down.

This "change in output capability" is only a max output level difference, in most cases. It is usually caused by by the power supply sagging and unable to maintain a constant rail voltage and through the IR losses across the output transistors and emmiter resistors.

Under normal to loud listening levels, the output voltage is load invariant. There are/were some poorly designed VI limiters that "kicked in" too early, but those days are pretty long gone. What is available are amps that have too little protection and allow themselves to blow themselves up because VI limiting is not present, or ineffective, making them leave their SOA's.

So, I wouldn't think you're missing any thing with an amp that doesn't double down. You can calculate the dB difference and you'll find (I think) that the difference is small and that it really doesn't mean anything unless you listen to constant tones at clipping.

Power ratings being what they are, perhaps my example was a poor one.

Your post is a good example of one reason why the subjectivist viewpoint is so attractive. After reading a post like that, a layperson is likely to throw up his hands in frustration that it's all incomprehensible and if he can just "trust his ears", he'll be OK. That's not a criticism, just an observation.

 

[kirk57]

I can assure you the active debate would be over in one song. And all the "why's" would mean squat to everyones ears.

What setup are you using marc? I have biamped Magnepans using a passive line level crossover between the pre and 2 power amps and actually preferred the sound of a single amp through the speaker's (heavily modified) passive crossover.

If actively biamping (with a Rane, Behringer, etc) the sound of the crossover itself also enters into the equation, doesn't it? I'm not disagreeing with your assertion, just saying it was not a slam dunk in my experience, but possibly I needed a different setup.

 

[blackfly]

Check out my siggy. I have the option of using 3 amps as a main. I have tried all 3 and not one of them sounds the same. The class A amp (Lux) is by far the best of the 3. The high power SS amp (Bryston) is clean, clear and robust, but lacks the warmth and liquidity in the midrange and upper end of the class A amp, but this could just as easily be a class A/class AB design debate.

However, you might find that the amp you love is fine with one speaker but dreadful with another, especially if the speaker has low impedences, bad conductance angles... get the amp with the most output current to prevent this.

But do NOT assume that because it is old they did not know what they were doing. There is a huge age gap in my two main amps and the older one (by 23 years) is the better one, despite age.

Listen for yourself and you might be suprised how little modern amps have come and perhaps how far ahead the older ones were. I am not saying this is the case with all old amps, but the TOTL ones for sure.

 

[marc mc]

What setup are you using marc? I have biamped Magnepans using a passive line level crossover between the pre and 2 power amps and actually preferred the sound of a single amp through the speaker's (heavily modified) passive crossover.

Other than giving you the option of biamping, I think you just moved the passive to a different location. And in that case I can see how the modded original would be better. I am not a fan of passive pre's or running CDP's direct to amps. I have 2 CDV-2's which are tubed CDP's with volume controls and have never prefered them direct to amps. I have not tried them direct into the active crossover though. I should try it.

If actively biamping (with a Rane, Behringer, etc) the sound of the crossover itself also enters into the equation, doesn't it? I'm not disagreeing with your assertion, just saying it was not a slam dunk in my experience, but possibly I needed a different setup.

I understand that pro gear is frowned upon by audiophiles. I thought is was poor for years, but that was just a stereotype that the audio circles ran with. Bryston suffered from that stigma for years and was labled as cold or hard sounding. The truth is I use 2 Bryston pre's that kicked some awesome tube pre's I owned to the curb. And the phono stage was just as good as the super touted Whest phono that set me back a grand.

I am not the type of person to shine things over. If I buy or try something and its not better I don't care how much or little it costs its gone. Good is Good and Crap is Crap. If a piece of gear gets its ass kicked by something else I try. I hand it a Kleenex for its bleeding nose and point to the door. I don't own or keep "novilties" or "Legends" for statis. With that said I think that Rane active crossovers are big and open sounding.



marc mc

 

[dlaloum]

In the famous words of Peter Walker (of Quad fame) - any adequately designed amp should sound like any other.

The only way to test is to

1) Ensure that all amps are running within their ideal design parameters
2) This means the speakers must match the amps capabilities

So if you wanted to test a range of amps, you would choose an extremely sensitive, crossoverless speaker with great micro-dynamics, and high efficiency... (Lowthers? Horns?)

This way regardless of whether testing the 10W wimp or the 1000W giant - you should still be within their optimal design envelope...

Even then all you would be demonstrating is that they do (or don't) sound identical with that specific speaker.

And to add insult to injury the 1000W monster is probably designed for difficult/inefficient loads, and it's optimal design envelope requires it to be doing some work - otherwise you may find the noise floor becomes noticeable (and then they don't sound the same anymore do they...)

Heh the only way to make this sort of comparison work is to take 2 amps of similar design envelope (similar current capability, power output, impedance of input and output, damping factor, etc...) - and then compare them.... chances are they will sound the same.

After all there is no point comparing a MAC truck with a Moped - they both have internal combustion engines - you are not going to move a container with a moped. But, they can both drive at the identical speeds of 5mph, 10mph, 20mph, and will probably match each others braking distance when unloaded at those speeds.

My own observations (like many here) have been that in the real world, with real speakers, you start by auditioning speakers you like..... - cos the transducer is the one thing with the very highest level of colouration and distortion....

Having picked the speaker then automatically sets the parameters of your amplifier selection.....
does the speaker have low impedance/require high current, what is its efficiency/how much power is needed.... etc...

Then there are the compromises.... for example (and looking at only one parameter...) my speakers efficiency is 88db/1wm

So to reproduce a full blown symphony orchestra at 2m from the speakers I need to reproduce around 115db. (110db at 1m but adding a bit for additional distance from the speakers)

Calculating back every 3db requires doubling of the power
115db - 88db = 27db
27db / 3db = 9

Double 1W nine times = 512W

So to effectively be able to reproduce Symphonic music I need a 512W RMS amp for my 8 ohm speakers...

Except that in the lower frequencies (around 100 Hz I think) the impedance drops to 3.5 ohm .... so for the woofer I need 1024W RMS (4ohm), and for midrange and tweeters 512W RMS (8ohm) will do.

So to test amplifiers for whether they sound the same I would need to be comparing 2 amplifiers rated at 512W RMS per channel @ 8ohm but capable of
doubling down into 4ohm.

Anything other (less) than that, and I would start suffering various forms of distortion - and depending on the amp design, and its interraction with the speakers, this would manifest in a different sound.

I currently run my speakers biamped, with 2x high current 140W RMS @ 8ohm per channel amps.... not even close to the "amps may be identical" required spec.

And I haven't even bothered to discuss the equivalent measures for Rock Concert volume levels (between 120-140db)

By the way - I usually watch movies at 10db to 15db down from "reference" levels - so I doubt I ever attempt the types of loudness levels discussed.

Given the volume I usually listen at the power levels drop back to circa 32W@8ohm and 64W@4ohm - well within the envelope of my amps... yet when I connect my Onkyo Receiver amp - in Stereo mode(I use the Onkyo as a pre into my power amps) - rated at 140W "continuous FTC" @ 8ohm - it sounds different - a little harsh

Given a current limit of around 9 A (the receiver is rated at 9.6, allow 0.6A for the preamp section) - My max power into 3.5 ohm is around 70W/channel - starting to get very close to the rule of thumb requirements for my speakers at my listening levels!! - and it is showing.

I then switch it into bridged mode (using some of the surround amps in the receiver) - theoretically capable of double the power !
The highs definitely sounding sweeter (well within the envelope) - still doesn't sound as good as the twin power amps when complex crescendo's strike. (is the bass sounding not quite right...?)
Although theoretically capable of 210W/channel (according to Onkyo) - the current constraints are still in place - speakers now bottom out at 1.75ohm - and the available current limits the amp to a grand total of ..... 35W.

Going back to my power amps (Quad 606) they are capable of continuous current per amp of circa 4A - no problem in the tweeter/midrange area - we can pump 140W@8ohm.
Come to the bass zone and .... 56W is all they can provide - we are back below the required threshold - back in distortion territory - back in subjective evaluations of which distortion sounds better.

So far I have found the Quad 606 pair to sound better than the Onkyo TX-SR876 - But they do not sound the same, and could not be expected to under the circumstances.
To meet the needs of my normal listening volume would require around 4.6A per channel for 73W @ 3.5ohm

And for "absolute" requirements - ie reproducing full orchestra - 18.3 A Per channel for 1170W @ 3.5ohm.

I suggest that anyone wanting to compare amplifiers to see whether they are (or are not) audibly identical, choose speakers with a sensitivity of over 100db - in my case that would have lowered the Power requirement from 1170W to 73W... I would lay bets that with a pair of speakers of that sensitivity I would have trouble discerning the difference between my amps.

Anyway the point is - within the design/engineering limitations of an amp they probably sound very very very close... but I do not have the wherewithal to test this hypothesis - based on my own experience to date I will support Peter Walkers statement "all well designed amplifiers sound the same".

And I will save my pennies to try and get an amp putting out circa 36A into 3.5ohm

I always liked the way Rolls used to advertise power rating for their motors - before the laws changed and they were obliged to provide specs - "Adequate Power" - and then there was Aston Martin -"Adequate under ALL circumstances".

 

[davidro]

My friend did what you are talking about. Sounds like what it is; A pile o' junk.
I would advise you not try it, its so bad I couldn't even laugh. I just turned and looked at him with a disgusted face.

Thanks for the input! Can you please tell me what speakers and amp they were?

I did, for a brief time. My power amp was destroyed in a move, and until I could get a replacement we connected my wife's old (as in, early 90's) Sony shelf system to my speakers. Once I disabled the Sony's bass booster and spent some time tweaking its 5-band EQ sliders (the tone controls) the sound quality was "acceptable" (as in it didn't cause us physical pain to listen to it) as long as the volume was kept low (think Muzak levels), but any attempt to turn things up higher made the difference obvious to the oldest, most untrained ear that heard it.

A 20wpc solid state shelf system does NOT sound the same as a 170wpc solid state power amp, at ANY level.

Thanks for the input. So the speakers were Muzak? And when the vol goes high, did it make distortion etc?

Yes, a T amp and Tannoy 6o9's (when comparing retail value of both, not when comparing what I actually paid..)

And how does it sound?

The heavier amp may be a less efficient class, more conservatively rated, have bigger heat sinks, a larger power supply, a milled aluminum faceplate, more protection circuitry, etc, etc. Most of these things may make a better amplifier, but not, perhaps, a better sounding amplifier.

So what are the actual advantages then? Like durability?

 

[gkimeng]

Thanks for the input. So the speakers were Muzak? And when the vol goes high, did it make distortion etc?

The speakers were AR-2ax's. And yes, as the volume was increased distortion rose quickly, even though the amp was nowhere near clipping. I think the WPC rating was probably measured at something like 5% distortion.