If you are using a truly BLIND A/B test setup please describe it. I have numerous speakers, preamps, CD and DVD players. They all tell the same story.
no I do not have a ABA testing setup but if you know what your listening too you can ...very quickly hear the differences/characteristics of each amplifier
there must be something common here at work find it and you may start to hear the differences....or again no disrespect to you ..you may just not be able to discern or quantify the differences its a learned talent ....
Lawrence
wow....terry there are thousands here that will agree with me ...it really is a learned talent
please...if you have no open mind how can you learn?..
and if all amplifiers sound they same why are you constantly building more? makes no sense
to each his own...
Lawrence
Thousands? I doubt it. I have a very open mind. There was a time when I too believed as you do that I could hear those subtle differences between different amps. In an effort to disprove nay-Sayers I went through the effort of making a blind A/B setup. Unfortunately, once I did this I found that what Rod Elliot and others had been saying was true. Once an amp reaches a certain point of low THD there is basically no audible difference between them. What I did discover was how much increasing or decreasing the volume of the output means to the sound. On click of increased volume can make an amp sound greatly different. THAT is the problem that so many face when trying to compare two amps without the ability to equalize the outputs and instantly switch between them.
When you tell me you have not compared using an blind A/B setup then for me, your findings are not valid.
I build amps for my enjoyment. It doesn't have to make sense to you.
When you tell me you have not compared using an blind A/B setup then for me, your findings are not valid.
I build amps for my enjoyment. It doesn't have to make sense to you.
we can agree to disagree i am not here to tell ya or convince you so but please dont say that there is no difference because you cannot or whomever cannot tell ...what proof is that ya?? again agree to disagree
good luck with your amplifier building
Lawrence
It has been stated by a few Amplifier Designers that all amplifiers (behaving and reproducing a scaled version of the input signal) that have the same frequency response sound the same.
They go on to say that the differences become evident when the amplifiers misbehave.
The major reason for misbehaviour is clipping. That could be current clipping, or voltage clipping. If one has an amplifier that never clips and it has the same frequency response, then you should "hear" that all sound the same.
The easiest way to avoid clipping is to never overload the amplifier. That means using the correct speaker impedance and using a power rating that is typically 100 to 300 times more than the average power level that you listen to.
If you use 1000mVac (1/8th W) as a typical average level to your 90dB speakers, then your average level is ~80dB @ 1m, or ~75dB @ 2.4m from 2 speakers.
A 10Vac output capability allows for unclipped signal of +20dB ref that 1000mVac signal , i.e. 95dB @ 2.4m
A 31Vac (+30dB ref 1000mVac) would allow 105dB @ 2.5m
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In general I agree and think that it is true. But in seeing the big picture, I disagree. Even worse than that, I think that there might be a big misunderstanding...
People think that when amps are equally "good" (notice the quote), they tend to sound the same because the difference is below (audibility) thresholds. And that "poorer" amps tend to sound different because they easily misbehave (low PSRR, high Zout, etc)... But really?
I suspect, "good" amps tend to sound the same because they simply follow the same "directions", which doesn't have to be the right direction.
You're suggesting that two amplifiers can process the signal incorrectly and differently but sound the same.
Is that a reasonable proposition?
I can add 222 +223 and get 445. Many others can do that and come up with the same answer.
But if one comes up with 418 and another 635 and another 172, What are the chances of coming up with the same wrong answer when there are 10^100 wrong answers and only one correct answer?
Is that a reasonable proposition?
I can add 222 +223 and get 445. Many others can do that and come up with the same answer.
But if one comes up with 418 and another 635 and another 172, What are the chances of coming up with the same wrong answer when there are 10^100 wrong answers and only one correct answer?
You have to factor that
Some people are fond of tubes and transformer designs. Lots of those options
Some people are fond of singleton such as what i see used in this thread.
Some like jfet front ends
Some like CFA over VFA
Some like low ppm distortion.
Some like them super fast
Some like no FB
Some like low open loop thd
So what features do you want? Lots of choices, which are more important than the other.
If your amp is going to clip you want the tube behavior over the bjt hard clip. I think the ole latfet is good solid state compromise.
With a CD source, use a passive pre-amp (pot) so you can take the pre-amp out of the picture.
Speakers are the most important.
Some people are fond of tubes and transformer designs. Lots of those options
Some people are fond of singleton such as what i see used in this thread.
Some like jfet front ends
Some like CFA over VFA
Some like low ppm distortion.
Some like them super fast
Some like no FB
Some like low open loop thd
So what features do you want? Lots of choices, which are more important than the other.
If your amp is going to clip you want the tube behavior over the bjt hard clip. I think the ole latfet is good solid state compromise.
With a CD source, use a passive pre-amp (pot) so you can take the pre-amp out of the picture.
Speakers are the most important.
Let's first give no definition to "correctness"...
No, my proposition was not that 2 (supposedly) inferior amps processing signal differently can sound the same, BUT 2 (supposedly) superior amps processing signal similarly can sound the same!
An example, yes, when an amp has high output impedance, it can sound different given wide variation in speakers. But if we use a proper speaker, is the high output impedance a mistake?
Another example, yes, when an amp has low PSRR of the input stage, it can sound different given wide variation in power line. But if we use a proper power supply, is the low PSRR a mistake?
So I hope my proposition is clear: When many amps sound the same, it is because they are designed with the same goals, not because the are "correct". Same logic with the opposite case.
Of course, the next question is what are the correct goals... But we know that there are compromises, so we need a "good" balance (that unfortunately will be affected by taste also).
It's not a tube/valve vs Solid State behaviour that you are describing.
It's the difference that feedback makes in trying to reduce distortion until finally it can't and the distortion due to the onset of clipping skyrockets.
Compare a (no global feedback) single ended valve to a single ended transistor.
Their distortion is similar.
Apply a small amount of feedback to both. Again the distortion is similar.
Increase to a medium amount of feedback. Distortion is similar.
Never said anything about FR can be different.
May be you're right, I'm not really sure I get your point, but none of those are related to my point.
So you have your point regarding the correct design goals:
(1) Flat frequency response. Can you specify where the -3db points are?
(2) Zero output impedance.
(3) A speaker that is not sensitive to source impedance. Like what exactly? Eight Ohms and +/-2 Ohms from 20Hz to 20kHz?
That's only 3 (and not precise). The more you add, the more you feel you need to "sacrifice" one or two of your goals. Try to specify a comprehensive one if you can. Then if you specify the details, be careful because I will ask you whether you can hear any difference if the threshold is increased or reduced
I notice that your standard is quite high regarding to the clipping requirement. Can you translate this into simple minimum requirements, such as how many amperes the transformer is capable of, how many capacitance is required, how big the woofer, etc. etc.? 105dB@2m for short term dynamic looks good to me. I have such system but never used them anymore.
Something to think about
Harmonic Distortion Weighting - Past and present is discussed.
http://www.gedlee.com/downloads/THD_.pdf
From time to time, I delve into Lynn's(you know the one) writings. If memory serves me well, He has described the subjective characteristic of each order of harmonic distortion from an amplifier.
Harmonic Distortion Weighting - Past and present is discussed.
http://www.gedlee.com/downloads/THD_.pdf
From time to time, I delve into Lynn's(you know the one) writings. If memory serves me well, He has described the subjective characteristic of each order of harmonic distortion from an amplifier.
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Jay
Hello my friend,
Quote: Another example, yes, when an amp has low PSRR of the input stage, it can sound different given wide variation in power line. But if we use a proper power supply, is the low PSRR a mistake?
what do you mean exactly by power line variation? voltage? or some other factor??
for the past 15 years I have noticed my hifi can sound different on a somewhat daily basis...I have measure power line voltage looked at it with a scope not much changes but the sound sure does...Ideas?
Lawrence
Hello my friend,
Quote: Another example, yes, when an amp has low PSRR of the input stage, it can sound different given wide variation in power line. But if we use a proper power supply, is the low PSRR a mistake?
what do you mean exactly by power line variation? voltage? or some other factor??
for the past 15 years I have noticed my hifi can sound different on a somewhat daily basis...I have measure power line voltage looked at it with a scope not much changes but the sound sure does...Ideas?
Lawrence
Hi Lawrence,
Not voltage sag (tho this has an effect), but I was referring to the contents of the supply line (noise). The LF and the HF. The LF is mainly the 100/120Hz hum, the HF is from switching devices connected to the power line.
Not everyone's house has clean power line. In my house, I can hear the interference to the audio if I plug in my laptop charger (it's a good Dell one) or my broadband Motorola modem.
Most efforts in amplifier design is towards the LF PSRR. It seems ridiculous to me. Why? Because this effort often unnecessarily complicates the circuitry, and my intuition (if not my ears) says that it (can) negatively affect the sound, while in reality, basics but careful layout and decoupling (and using quality caps) is sufficient to bring hum to inaudible level!
May be from the surrounding switching noise? At night when you turn off most of the electronics, the supply should be cleaner. And might be affected by neighborhood electronics as well.
Hi Mooly can you check whether you can make pcb in coordinate with jims audio ebay to restart and get live your project.Most of the users including me like to try but dont have the time to go behind pcb making and all.So if you put an effort to get some PCB here that will be really nice to restart this project
Hi, and thanks for the interest.
I've no PCB files as such for this amp as it was all done in my pre PC days, the old fashioned way with hand drawn and hand produced boards. The circuit design itself is still as valid as ever though, and I've no objections if anyone wishes to produce boards from the material in this thread.
I've no PCB files as such for this amp as it was all done in my pre PC days, the old fashioned way with hand drawn and hand produced boards. The circuit design itself is still as valid as ever though, and I've no objections if anyone wishes to produce boards from the material in this thread.