An Amp Sonics side-thread

[planet10]

Split from here Sealed Enclosures

Originally posted by R-Carpenter
[Don't think the amp should be a consideration for a choice of a driver.

The speaker should never be considered without knowing what kind of amp you will be using. The amp (or more correctly the amp given the load provided by the speaker) can make a huge difference in how a system sounds.

After all amp (with enough power) will make little or no difference in the outcome.

False. Very false.

dave

[MaVo]

Originally posted by Brett
True. Very true.

In which way does a different amp affect the sound? I suppose you are not speaking about noise levels or the harmonic distortion of tube amps.

[Brett]

Originally posted by MaVo


In which way does a different amp affect the sound? I suppose you are not speaking about noise levels or the harmonic distortion of tube amps.

Big question, but here is a short answer; you need to puzzle the details yourself.

THD: level, spectrum and how the spectrum changes with level. Also class; AB has worse distortion with decreasing level.
Noise: irrelevant in any well designed and implemented design
NFB; use of or not, level of NFB and how it's implemented
Output Z: can be of use if factored into some designs. Needs to be minimised in others.
Balance in PP CCTs: needs to be maintained under dynamic conditions. How you achieve that will sound different
Clipping behaviour: Amps should never clip, but when they do, how do they behave and how long before they settle.
Component quality: I find it better to design assuming there'll be as little NFB as possible.
Design: Linearity, linearity, linearity. And headroom
Power Supply: it's in series with the amp so make it as inaudible as possible
+ a myriad of other little build details.

[vasyachkin]

when it comes to amps i think that all good ones are the same, but not all "hi-fi" amps are good ... in fact most probably aren't.

if you have a solid amp that is flat 10hz - 50khz with 0.01THD, 2 ohm stable and with 10 times the power that you actually need then i think it should be transparent in the system.

such amp does not have to cost an arm and a leg. my QSC Audio PLX seems to be just fine and it costs about 35 cents per watt.

i had some other amps that were simply useless though (a Technics from around 1997 and a NAD probably from around same time). people would have me believe that the NAD will sound good even though its specs are weak simply because its british ... not so. apparently brute force still counts for something. apparently being british cannot make up for having 10 times the distortion, 10 times the noise, 10 times the output impedance, half the bandwidth and 1/10th the power.

i think in practical terms there are 3 problems with powering speakers:

1 - PA amps have loud fans
2 - PA amps are too big to run tweeters actively off of
3 - i like PA amps

[vasyachkin]

Originally posted by Brett
Clipping behaviour: Amps should never clip, but when they do, how do they behave and how long before they settle.

in a commercial application it only makes sense to run the amps full scale, but at home i think we can avoid clipping altogether by simply using a bigger amp. if the amp is something like class H there will not be much penalty in electrical bills.

i would love to use a class A amp in theory, but in practice no serious company (like Crown) will bother producing a class A amp because of how impractical it is. in practice i would rather use a class H amp of an excellent design and low cost than a class A amp of a poor design and high cost.

of course if you want to design and build your own class A amp then clipping will be a concern.

[R-Carpenter]

Originally posted by Brett
True. Very true.

I knew I was going to strike someone’s nerve with “Amp makes no difference” remark.

Unless we are talking about hopeless 1-watt class A tube design, I stand by my point. 99% of solid-state amps out there, given the fact that isn’t driven to clipping (as I mentioned before, “having enough power”) aren’t very much distinguishable in sound. Blind test have proven it number of times. I have been through about 8 blind tests, listening to the amps ranged in the price between $300 and close to $7000. No audible difference was found (5 more people participated in the tests, tests were done on 2 pairs of commercial speakers, ranged between $4500 and $5000 in price). Does it mean they will measure the same? Not at all but our hearing is much less sensitive then an oscilloscope. “Can’t you hear that?!” becomes useless with equipment covered up.
I have 1500 square foot shop and a SPL meter. If you want to prove me wrong, bring it. I will be first one to say, “I was off beam”.

I am not even going to go into solid state vs. tube argument but the point is that Speaker system makes the biggest impact on the sound reproduction! Why? Because unfortunately, there’s no ideal speaker system out there yet. They are all colored and have different frequency ups and downs and of axis response. In fact, room-speaker interaction gives it an infinite number of possibilities in coloration = character of a speaker.

The audible differences between electrostatics, magnetic planar type, horns, open baffle and as we talking about ported vs. sealed enclosures are major. It is first intelligent to consider, which type of coloration you prefer (ported or sealed in this instance) and perhaps think of enough wattage later, based on the efficiency of the driver and the impedance behavior of the speaker.

I always build my speakers with the impedance compensation to make amps life easier and prevent the impedance from dropping down below 3.5-4 ohms and jumping over 20 ohms at cone resonance.

[tinitus]

I have heard clear differense between good amps and VERY good amps, although very small differense its enough to make it very important...if quality matters more than quantity

No matter how well a speaker is designed, a good amp may in many cases be the very key to nirvana of sound

But some speakers demand fore more stable amps than others

Sure, you can do a setup where it probably doesnt matter much, but that doesnt make it a general rule

BTW, 5-7000USD worth of amp doesnt automatically mean its any bit better than cheaper ones

Speaker technology has changed rapidly and today its probably much easier to find a good speaker than a good amplifier...but thats only pure speculation

[vasyachkin]

Difference between NAD and QSC is like night and day. NAD sounds like FM radio between the stations and yet many people recommend it so its entirely possible to buy an amp that is supposed to be good and wonder why your speakers sound miserable.

just because its easy to make an amp sound transparent doesn't mean that even most amps are made that way.

instead a lot of people don't want to buy amps with op-amps in them (like QSC) so they go for fully discrete designs (like NAD) and in a discrete design there is a temptation to cut corners by throwing out some parts (to save money) and then you're left with an amp that sounds just barely good enough for most people buying it not to notice how bad it is.

if audiophiles could get over their religious beliefs maybe things could start to improve, but i think the 99% figure is way off ... maybe 10%.

[vasyachkin]

Originally posted by tinitus
Speaker technology has changed rapidly and today its probably much easier to find a good speaker than a good amplifier...but thats only pure speculation [/B]

amplifier technology changed a lot more than speaker technology. after all speakers are copper, aluminum and wood and amps are silicon.

i will venture to say that it will never be easier to find a good speaker than a good amp ... but thats only because speakers are nowhere even close to being "good enough" today.

[planet10]

Originally posted by vasyachkin
if you have a solid amp that is flat 10hz - 50khz with 0.01THD, 2 ohm stable and with 10 times the power that you actually need then i think it should be transparent in the system.

That is exactly the kind of amplifier that doesn't sound very god on most of my speakers. Damping factor is too high and the efficency of the speakers will have that amp running at its worst.

at home i think we can avoid clipping altogether by simply using a bigger amp.

But that is counter to the general tendency that sound quality is inversly proportional to power output -- hence design of speakers specifically to mate with very high quality 2-10W amplifiers.

dave