HIFI or high fidelity was first used in the 1930ths when the first uses of GNFB were used. Never post on the eighth beer.
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On Effects Boxes, two weeks ago I listened to a Chinese AM 833S, a version of the WAVAC 833 SET. Here's the picture:
AM Audio 833S Mono Amplifiers | News | StereoNET
These are much cheaper than the original, which is around $USD350k.
I would imagine THD would be around 1%, probably up around 10% at the stated 124W into 8R. Actually I'd be surprised if it goes more than 100W; the B+ on the 833A is only 900V at 220mA. Utterly quiet, and an enough heat and light to cook your breakfast and read a tabloid newspaper. Lineup is ECC88, KT88, and 833A, 75 Kg EACH - two monoblocks - each consuming 400W of precious electric power.
Despite the THD, despite the lower voltage, despite tens of kms of transformer wire, and despite a topology created a hundred years ago, this amplifier is arguably the best 'hifi' component I have ever heard.
It does take about half an hour to hit its stride. But it does deliver exceptional sound quality for an effects box; it completely blows away any amp I have ever heard, including my Class A SS attempts made early in my career. This may or may not relate to this thread, but FWIW the AM 833S has no global feedback.
AM Audio 833S Mono Amplifiers | News | StereoNET
These are much cheaper than the original, which is around $USD350k.
I would imagine THD would be around 1%, probably up around 10% at the stated 124W into 8R. Actually I'd be surprised if it goes more than 100W; the B+ on the 833A is only 900V at 220mA. Utterly quiet, and an enough heat and light to cook your breakfast and read a tabloid newspaper. Lineup is ECC88, KT88, and 833A, 75 Kg EACH - two monoblocks - each consuming 400W of precious electric power.
Despite the THD, despite the lower voltage, despite tens of kms of transformer wire, and despite a topology created a hundred years ago, this amplifier is arguably the best 'hifi' component I have ever heard.
It does take about half an hour to hit its stride. But it does deliver exceptional sound quality for an effects box; it completely blows away any amp I have ever heard, including my Class A SS attempts made early in my career. This may or may not relate to this thread, but FWIW the AM 833S has no global feedback.
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Small issue: Age related Hearing degredation is REAL.
In a perfect world No One of age 60 (Or arguably age 30..If One was being Honest).. Would be allowed to review ANY audio product.
More than a Bit like having your Gran review or Gawd forbid: 'evaluate' Cross trainers.. Ain't it??
In a perfect world No One of age 60 (Or arguably age 30..If One was being Honest).. Would be allowed to review ANY audio product.
More than a Bit like having your Gran review or Gawd forbid: 'evaluate' Cross trainers.. Ain't it??
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Indeed, it almost looks like a reasonable price compared with the the top-end SS stuff I see in the odd magazine (I laugh my socks off at pretty much every hi-end audio magazine these days).
Global feedback or not, isn't the secret sauce supposed to be in the OPT - hard to put an OPT in a feedback loop though.
Edit: I think experience counts for a lot, the over 60's have plenty of life in 'em yet.
p.s. Hugh - you deserve a pair of these, you know you do 🙂
Global feedback or not, isn't the secret sauce supposed to be in the OPT - hard to put an OPT in a feedback loop though.
Edit: I think experience counts for a lot, the over 60's have plenty of life in 'em yet.
p.s. Hugh - you deserve a pair of these, you know you do 🙂
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Bigun,
I like them, beautifully built, but it affronts me..... particularly the transformers.
I'm working on a SEmosfet at present using the FQA36P15. The biggest problem is dispensing with the heat; I calculate around 130W per channel for 45W. Looks good, and with a tube carefully operated in front, it should sound very, very nice, and a lot cheaper.
I really don't have a nice enough listening room for a SET, and I really don't like the power waste. But I can enjoy David's AM 833S, and do you know, he is 75 years old!! Just bought a diesel Jaguar, actually, he is very spritely.
Hugh
I like them, beautifully built, but it affronts me..... particularly the transformers.
I'm working on a SEmosfet at present using the FQA36P15. The biggest problem is dispensing with the heat; I calculate around 130W per channel for 45W. Looks good, and with a tube carefully operated in front, it should sound very, very nice, and a lot cheaper.
I really don't have a nice enough listening room for a SET, and I really don't like the power waste. But I can enjoy David's AM 833S, and do you know, he is 75 years old!! Just bought a diesel Jaguar, actually, he is very spritely.
Hugh
Hugh, speaking about no GNFB hybrid solutions, I would suggest you try also output bjt triplet instead of FQA36P15. Somehow, without possibility to argue technically, the kind of output power transistor affects bass articulation and bass impression in general. As for me, laterals are worst, bjts are the best for bass. But, in my system, 40cm2 output trafors at tube output give even better bass, naturally articulated.
Vladimir,
Thank you for your timely post; you strike a chord with my experiences with bass!
I am assuming you mean a triple darlington configuration? I would be using 2N5551/2SC4793/2SC5200 and the complements would be OK?
Most appreciative,
Hugh
Thank you for your timely post; you strike a chord with my experiences with bass!
I am assuming you mean a triple darlington configuration? I would be using 2N5551/2SC4793/2SC5200 and the complements would be OK?
Most appreciative,
Hugh
I am not sure that C5200 are what we need, but not ready to propose definite better alternative. We need power transistors with the extremum of h21 vs Ic curve in the range 4...7 ampears.
I used russian KT947A (radio frequency 300W power transistors), and they have growing h21 up to 15A.
And, 2N5551 is not good as an input transistor.
Where is the threshold from an accurate amp to an "effect box"?
And how is this determined? (i.e. who is able to day "this is not an effect box but transparent and everything that sounds different in a DBT is an effect box or not neutral)
And how is this determined? (i.e. who is able to day "this is not an effect box but transparent and everything that sounds different in a DBT is an effect box or not neutral)
You answered your own question. If the output is indistinguishable from the input in an ears-only test, it's transparent. If it is distinguishable, it is an effects box. As long as the design engineer has a clear idea of what his goal his, he can design in either direction. The tricky job is the latter- designing transparent electronics is easy, designing stuff that has a desired "sound" is quite a bit trickier, especially validation.
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I have found good results using a BJT-FET combination. I think there's more than one way to skin the cat.
Hugh - that hybrid sounds too 'hot' to me. My plan is for less than half that power level (I think you've seen my circuit already).
SY
Would that not imply a perfect transparent source or speaker for that matter.
I have often wondered how anyone can audition anything with dome tweeters. They are simply not physically able to resolve the way a 30-50 times lighter ribbon tweeter does.
So when we're talking DBT. Then it may well be that that the results you're getting or not getting is due to rest of your "test" equipment.
Would that not imply a perfect transparent source or speaker for that matter.
I have often wondered how anyone can audition anything with dome tweeters. They are simply not physically able to resolve the way a 30-50 times lighter ribbon tweeter does.
So when we're talking DBT. Then it may well be that that the results you're getting or not getting is due to rest of your "test" equipment.
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amp performance can be evaluated in the electrical domain, divider at speaker terminals, decent prosumer soundcard - by all means use 24/96 or 192k
Audio DiffMaker implements a very high quality "null test", or you can use a diff amp, but often need some frequency response corrections for deep nulls
if that doesn't show you enough then foobar2000 abx, Senn HD-600 or similar decent headphone allows listening test with blinding, few will ever have lower distortion speakers, better time resolution in multiway speakers, room with multiple reflections
Audio DiffMaker implements a very high quality "null test", or you can use a diff amp, but often need some frequency response corrections for deep nulls
if that doesn't show you enough then foobar2000 abx, Senn HD-600 or similar decent headphone allows listening test with blinding, few will ever have lower distortion speakers, better time resolution in multiway speakers, room with multiple reflections
Aha, OK, so I need to measure and if input=output, it's transparent.
However, I'll never manage to develop such an amp.
Input is never going to be = output, maybe close, but not 100%.
Therefore, I need a design goal.
So, when does it start being an effect box?
at say 1 ppm distortion?
And what about 100 ppm?
0.1 %?
1%?
10%?
Has it been ever tested blind, DBT, when it starts to be an effect box?
Of course, all else which has importance to listening test outcome being equal (level, FR)