Yes of course I want it to be exactly +/- 500mV. If the max. speed is 55 mph you want to drive that don't you!
😉
Thanks for that very informative link to us illiterates (on electronics) so now we can fiddle around with our consumer audio electronics from NP.
😉
Thanks for that very informative link to us illiterates (on electronics) so now we can fiddle around with our consumer audio electronics from NP.
just in case that you're not joking - figure of 500mV for absolute offset is max.
less is better
so leave it as is, fiddle with offsets only if you go for declared Iq and that brings some change in offsets
anyhow, commence with fiddling only when everything sits in your brain and you have exact idea what you're intending to do
less is better
so leave it as is, fiddle with offsets only if you go for declared Iq and that brings some change in offsets
anyhow, commence with fiddling only when everything sits in your brain and you have exact idea what you're intending to do
I'm really happy with your advice (as always) and you should be the European technical headmaster for Pass affairs.
Now for something slightly different:
Fifteen years ago I posted this question on the Pass Labs Community:
https://www.diyaudio.com/community/...asting-power-is-something-of-the-past.104589/
I got roasted for it but NP found it a legitimate question.
In that time D'Agostino already made his first series of plateau biasing amplifiers, Jeff Rowland was busy with small Class D amplifiers and Levinson didn't make amplifiers anymore like the famous ML-2's and their No. 20 derivatives. The Japanese had made dozen of copycats from the patented NP classic the Threshold 800A sliding bias (patent 1976).
With a keen eye on the exploding energy prices would it meanwhile be possible to refine or otherwise update this sliding bias patent and make a modern Pass Labs variant that sounds at least as good as the X series amplifiers? It's an open question and in no way an attack or disqualification of the current fixed bias designs of Pass labs. I'm genuinely interested if this is a possible strategy for the future?
Fifteen years ago I posted this question on the Pass Labs Community:
https://www.diyaudio.com/community/...asting-power-is-something-of-the-past.104589/
I got roasted for it but NP found it a legitimate question.
In that time D'Agostino already made his first series of plateau biasing amplifiers, Jeff Rowland was busy with small Class D amplifiers and Levinson didn't make amplifiers anymore like the famous ML-2's and their No. 20 derivatives. The Japanese had made dozen of copycats from the patented NP classic the Threshold 800A sliding bias (patent 1976).
With a keen eye on the exploding energy prices would it meanwhile be possible to refine or otherwise update this sliding bias patent and make a modern Pass Labs variant that sounds at least as good as the X series amplifiers? It's an open question and in no way an attack or disqualification of the current fixed bias designs of Pass labs. I'm genuinely interested if this is a possible strategy for the future?
My approach more recently has been on two fronts -
Push-pull square law stages that have much bigger Class A envelope for a given bias.
Lower power amplifiers paired with efficient drivers.
I might add my other patent for efficient Class A using a "floating cascode" which has not been manufactured.
Push-pull square law stages that have much bigger Class A envelope for a given bias.
Lower power amplifiers paired with efficient drivers.
I might add my other patent for efficient Class A using a "floating cascode" which has not been manufactured.
Thanks for your answer.My approach more recently has been on two fronts -
Push-pull square law stages that have much bigger Class A envelope for a given bias.
Lower power amplifiers paired with efficient drivers.
I might add my other patent for efficient Class A using a "floating cascode" which has not been manufactured.
I'm not a technician but the push-pull square law stages with a bigger Class A envelope you referring to, have they emerge anywhere in your current line-up of amplifiers?
The use of efficient loudspeakers permits the use of lower power amplifiers like your stereo 2 X 30 Watt XA30.8 which still takes 400 Watts from the wall according to your latest brochure. It's more economical than the XA200.8 which uses 1500 Watts the pair of course.
So you have two patents that enables you to develop efficient Class A amplifiers and although both patents are no longer valid because of the passing of the years, your brand name is so strong that you can make them without much competition.
Is there any chance we would see one of these schemes (or the combination of it) in the near future arise from Pass Labs? At least you could offer them alongside the current line-up because I think the fixed bias solutions are very much associated with your name.
All of the push-pull products enjoy some square law effect, but the XA25 has taken it to the max, as we completely
eliminated degeneration in the output stage.
None of the PL amps would be considered low draw, but then they are designed for high current. For modest consumption
you would have to go to First Watt.
The problem with low consumption bias schemes is that they are not popular - the competition brays "not really Class A!"
or "Not PURE Class A!" and so this is viewed with suspicion in the marketplace.
Better off to be Class D. 😉
eliminated degeneration in the output stage.
None of the PL amps would be considered low draw, but then they are designed for high current. For modest consumption
you would have to go to First Watt.
The problem with low consumption bias schemes is that they are not popular - the competition brays "not really Class A!"
or "Not PURE Class A!" and so this is viewed with suspicion in the marketplace.
Better off to be Class D. 😉
Okay I deduct that there won't be any floating cascode or sliding bias amplifiers in the near future under the Pass Laboratories brand name.
Today I experienced the first colder day (12 Degrees Celcius outside) from the year in my studio and even my underbiased (280 Watts draw instead of 550 Watts) X600.5's did slowly help me out with their radiated heat. Natural gas is four times as expensive as last year and electricity two times so it's now more "economical" to heat my room with the X600.5's than with gas. As a bonus I can enjoy their sound.
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let's just say that Pa is having much clearer conscience and much smaller carbon footprint than Producers of Weaponry
Haha, entertaining non-audiophile visitors. Extinction delay switch? You mean the delay of our extinction due to the so-called greenhouse effect that will engulf places like Martha's Vineyard to begin with?
Patents of NP:
https://patents.google.com/?inventor=Nelson+S.+Pass
1. Active bias circuit for operating push-pull amplifiers in class A mode: Threshold 800A
2. Active low frequency acoustic resonance suppressor: TubeTraps
3. Amplifier with gain stages coupled for differential error correction: Super-Symmetry, all Pass X power amplifiers.
4. Opto-isolated bias circuit for operating push-pull amplifiers in class A and Class AB modes: introduced in Threshold 'optical bias' models S/200 - SA/1.
5. Amplifier having an active current source: Aleph series??
6. Constant voltage - constant current high fidelity amplifier: introduced in Threshold Stasis 1, 2 & 3.
7. Efficient high fidelity audio power amplifier: floating cascode, not implemented?
https://patents.google.com/?inventor=Nelson+S.+Pass
1. Active bias circuit for operating push-pull amplifiers in class A mode: Threshold 800A
2. Active low frequency acoustic resonance suppressor: TubeTraps
3. Amplifier with gain stages coupled for differential error correction: Super-Symmetry, all Pass X power amplifiers.
4. Opto-isolated bias circuit for operating push-pull amplifiers in class A and Class AB modes: introduced in Threshold 'optical bias' models S/200 - SA/1.
5. Amplifier having an active current source: Aleph series??
6. Constant voltage - constant current high fidelity amplifier: introduced in Threshold Stasis 1, 2 & 3.
7. Efficient high fidelity audio power amplifier: floating cascode, not implemented?
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