Putting an air gap in the OT lowers the primary inductance, which generally is not a good thing. But a small amount will provide some immunity from DC imbalance, without having to use a DC bias servo. E-I cores do it just about right for the P-P case. A nickel alloy pin-striped E-I can give you improved permeability for small signal levels, similar to an oriented cut-core or toroid.
If you want to experiment with some 2nd harmonic, just unbalancing the splitter or driver stage load resistors should give you near perfect 2nd harmonic injection. You probably don't want more than a couple percent. And cap coupling to the outputs can remove most of the DC component if they are biased equally. While tube loading will give 2nd, 3rd, 4th in a trailing sequence. DC into the OT puts 90 degree magnetizing current into the outputs and probably some phase shifted 2nd harmonic from AC permeability variation. I really couldn't say what the relative merits are soundwise. Low Zout from the output stage probably would fix the OT behavior besides.
If you want to experiment with some 2nd harmonic, just unbalancing the splitter or driver stage load resistors should give you near perfect 2nd harmonic injection. You probably don't want more than a couple percent. And cap coupling to the outputs can remove most of the DC component if they are biased equally. While tube loading will give 2nd, 3rd, 4th in a trailing sequence. DC into the OT puts 90 degree magnetizing current into the outputs and probably some phase shifted 2nd harmonic from AC permeability variation. I really couldn't say what the relative merits are soundwise. Low Zout from the output stage probably would fix the OT behavior besides.
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Yes, it will be a constant current source with a mu stage and a DC servo used at the cathode to lock the bias in. There will be silicon used but only in two places since it will be tube rectified.
I built 300B SE mono blocks for use powering mid drivers in a 4-way system
and later converted them to triode KT88's. I was having problems on one amp
where the heater/cathode resistance was breaking down, so I dismantled them
and sold the components. I tried replacing them with solid state (ESP P3A,
P101, DOZ), but was never able to recreate the sound.
IMO, SE KT88 amps are best utilized powering high efficiency composite mid
drivers in a multi-way system, i.e.; the low power doesn't lend itself to much
anything else.
and later converted them to triode KT88's. I was having problems on one amp
where the heater/cathode resistance was breaking down, so I dismantled them
and sold the components. I tried replacing them with solid state (ESP P3A,
P101, DOZ), but was never able to recreate the sound.
IMO, SE KT88 amps are best utilized powering high efficiency composite mid
drivers in a multi-way system, i.e.; the low power doesn't lend itself to much
anything else.
THD witch hunt should be stopped, its not funny at all.
All musical instruments, have typical sonic signature. Thanks to different amount of harmonics. As it been said long time ago, 3 or 5% difference 2ndHD is hard to spot.
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One instrument can give pure sinewave, so far i heard it only in techno music. It´s called signal generator
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I am thinking for a while about shade-d SE with 1642 hammond. 4-250A would fit nicely, around 1500Ua ~130m Ia. Pa idle ~200W
Bad thing is the opt is only 5k, but 8r to 4 winding should do trick. This would put max out of the opt 75W
~ 50H should be ok bass wise
Unfortunately hammond does not list optimal current
It is rather misleading to put harmonic distortion generated by an amplifier on a par with the natural occurrence of harmonics in the sound of a musical instrument. For one thing, the distortion in an amplifier (whether 2nd, 3rd or any other harmonic) gives rise to intermodulation distortions between the different frequencies contained in the audio signal, and these are never desirable.
By contrast, the fact that a violin note comprises harmonics as well as the fundamental does not mean that it causes intermodulation distortions among the sounds from all the other instruments in the orchestra!
Chris
The purpose of a power amplifier is to provide a scaled version of the input signal to the speaker. Nothing added and nothing of the wanted signal taken away.
Amplifiers generate harmonics and IMD. Instruments produce overtones, which are sometimes only approximately equal to harmonic frequencies. Therefore it is a mistake to equate harmonics and overtones.
It is also a mistake to confuse the harmonic structure which is specific to a single instrument with applying a harmonic structure blanket wise to all instruments. After all we don't want every instrument to sound like a violin do we.
Shoog
Shoog
Ideally, but impossible.
I agree that we must design power amplifier closest as ideal conditions. If we design power amplifier with a special character than we call it, sound effect. But many people seem want of a sound effect rather than power amplifier 🙄
Measurably impossible, yes.
Audible impossible, no. And you don't even have to spend a fortune.
Sure , why build amplifiers than? Looking at some responses from more technically skilled electricians I'd assume that their constructions reached plateau and should basically sound the same whatsoever , doesn't matter the technology , topology and parts used .
There can be only ONE true reference which doesn't subtract nor add. Since you guys seems to have it I want to hear it , seriously.
best L
There can be only ONE true reference which doesn't subtract nor add. Since you guys seems to have it I want to hear it , seriously.
best L
there can be lots of audibly transparent amplifiers - the inevitable "errors" just have to be below human audibility with the music, speakers, signal levels required
also includes EMI/PSRR, ect - things real engineers do actually know how to design for and test - some required by CE
multiway speaker XO, exotic drives can cause surprisingly high current demands
some music genre, good recording practice can require high dynamic headroom
there are some possible amp/speaker mismatches that I suspect get overstated
these issues should be easily avoided or designed for by those with enough knowledge to be competent diy builders
there is good reason to think that transparent audio amplification was achieved some time ago - not that that is everyone's goal either in mass market or audiophile land
speakers and rooms are where any rational evaluation of home music reproduction limitations will have you putting money, effort
also includes EMI/PSRR, ect - things real engineers do actually know how to design for and test - some required by CE
multiway speaker XO, exotic drives can cause surprisingly high current demands
some music genre, good recording practice can require high dynamic headroom
there are some possible amp/speaker mismatches that I suspect get overstated
these issues should be easily avoided or designed for by those with enough knowledge to be competent diy builders
there is good reason to think that transparent audio amplification was achieved some time ago - not that that is everyone's goal either in mass market or audiophile land
speakers and rooms are where any rational evaluation of home music reproduction limitations will have you putting money, effort
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No , there are very few audibly transparent amplifiers if any . All else being equal non of them sounds the same when you plug one in the system. How can you call that transparent? Same with cables and anything in the chain.
Who's to judge the level of transparency ? Raised on GMO millennial with the taste of Pterodactyl and DMM meter ?(to paraphrase Romy😉
Who's to judge the level of transparency ? Raised on GMO millennial with the taste of Pterodactyl and DMM meter ?(to paraphrase Romy😉
Yes. 99% of all tube amps are guitar amps and these are part of the instrument. But here we are talking about the 1% of the tube amp world that is reproducing recorded music. These HiFi amps should try to be somewhat faithful to the recording.
With HiFi tube amps I think we all know we can't make them perfect so what the various designs to is try and make the "color" of the distortion acceptable. As it turns out the distortion of a SE amp is not bad sounding even in the single digit percents of THD. This is NOT true of transistor amps.
We already have amps like that. Audibly transparent amps are mass produced and distributed throughout the electronics market these days.
It's also called SET amp.
People have preferences. Catering to that is the business many people make living off of.
I will have to dig again into Romy's wisdom . Most of us run from one thing to another like "wounded in the as s antelope" because we don't have a benchmark , cultural background , taste and technical/ critical ability to discern what a system supposed to do and how to proceed to realize that goal. An because we lack that ability we tend to rely on opinions of chimpanzees writing in audio magazines and on internet forums. It's all good as long as we make that decision consciously and are honest with ourselves about the real motives. I can really enjoy music on cheap SS mini-tower as long as nobody make pretentious claims regarding relative quality of playback.
Rgrds, L
Rgrds, L
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