What you say is true. However, the original unsubstantiated claim by mrlowmu that led to criticism was that AC plug orientation affected sonic quality that is distinct from and not related to hum and noise........a claim which Hari conveniently chooses not to assess.
New Design, SE 6005 Directly Coupled Audio Amplifier
- Thread starter drlowmu
- Start date
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RtoR King
Active Member
Yes, I could see how reducing hum and RF noise could improve detail and clarity. But if you already have inaudible hum and noise or swapping the line cord doesn't reduce it, eg, amplifier internal 60hz hum, I don't see how any improvement could be made.
There is no audible hum in my LP playback system, and the only broadband random noise that exists is that which is due to the 1500 ohm resistance of my phono cartridge, and that noise is totally overwhelmed by the residual noise floor of the LPs to which I listen. The claim that the orientation of the AC wall plug of either my phono preamp or my power amp affects the reproduction of the music that is on the vinyl is absurd and utter nonsense.
I too did not have any audible hum on my setup. Only the field coil power supply had a micro hum once I place my ear on the cone. This too vanished after I connected a 0.1uF, 400vdc polyester capacitor from the -ve rail to earth.
I don't have such a golden ear to assess sonic virtues by this small change TBH and any claims would be me hallunicating which I am avoiding.
I don't have such a golden ear to assess sonic virtues by this small change TBH and any claims would be me hallunicating which I am avoiding.
Good Hari,
LOL, your original E.E. education is showing . Your answer is just not good enough - at all - for me !!
Do not allow your own pre-concieived notions keep you from TRYING, and most importantly, from finding out what the real truth is !!
It is time for you to FINALLY set the AC polarity, internally, for each of your monoblocks. YES, you DO have adequate hearing, IF you just A-B it properly. What is properly??
DO NOT use the usually-sourced cheapest possible long thin wire clip leads. Make up some Mil Spec clip leads, I use seven inch long 14 AWG m22759/11 wire lengths, and I use pure COPPER , unplated clip leads, readily available on line. See photo below.
Do the procedure precisely as I have reported above in this thread, and report back to us all.
Make notes, mark ONE lead of each AC connection with a indelible magic marker, so there is NO way to get polarity confused.
Play a digital recording of DEMANDING music and make sure you stop and start at the same spot each time. No longer than one minute of demanding program material. Back and forth, back and forth. Over and over again. Play it loud !! All you need to do is determine what orientation sounds best, remove the clip leads, SOLDER the wires into the circuit, and go on to the next spot in your KT88 SE amplifier.
In this thread's stereo 6005 amp, by ear A-Bing on music, I had to reverse four out of five locations. It was appreciably better, surprisingly so, once the work was performed. Maybe, subjectively, in my own home's transparent, well wired, high efficiency ALTEC VOTT A7-8 horn system, the amplifier became 5 to 8 percent better in overall fidelity.
No one in audio I am aware of ( except me and Dennis Fraker ) does this internal polarity AC polarity optimization Hari. I just started doing this in my mid-2019 KT88 build. This is well-beyond any normal EE's thought processing capabilities, ( due to their training ) as we can all see here in this thread............ BEAUTIFULLY . LOL. But it is what I hear, and hearing it undoubtedly solves the question completely !! One cannot deny the truth.
You have two mono amps, with TEN total locations to listen to, and optimize. Do it to one mono amp, and compare it against the other .
ONLY by doing this Hari, will you ever hear your amps at their best, and hear your amps properly Hari. !!
On almost every schematic I have sent you, I have made mention of individually aligning the AC phases of each transformer and it's associated windings.
It has not been done. No laziness. No EE-type mental blocks. No excuses.
Also, Hari, buy a proper sized stubby Phillips screwdriver, and REMOVE the Softone RW-20 Output transformer's stock steel covers !! Those steel covers on your R-Core output transformers alone, are about a 3% fidelity degrade !!!
If I can readily make such determinations - on this thread's 6005 stereo amp - in a few hours of A-Bing and re-soldering, ( with me being maybe 20 years older than you ) , you certainly can. But you certainly must TRY !!!
Jeff ....................................... Note my special clip leads below in photo, red and black insulators !! Very good amp :
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I have been avoiding to write any comments here, but @Dr.Gary and @R2R KIng it is better not to bother with the revelations provide by @drlowmu in his subjective audio research journey.
Those are his findings and if that is attracting some followers, so be it.
It is not worth wasting energy or trying to disprove his so claimed audiometric findings with scientific facts and truth.
I had some differences of opinion with him in his way of presenting his finding by claiming that the rest of the world is foolish. But we sorted it over PMs, and he has scaled down the tone, but once in a while does get an adrenaline flow.
I suggest we leave him and his build thread in peace, it is not worth anyone's time, neither you both's, his nor his followers.
There are billions of megabytes of misinformation floating in the web, are you both going to stop or question all of that?
Those are his findings and if that is attracting some followers, so be it.
It is not worth wasting energy or trying to disprove his so claimed audiometric findings with scientific facts and truth.
I had some differences of opinion with him in his way of presenting his finding by claiming that the rest of the world is foolish. But we sorted it over PMs, and he has scaled down the tone, but once in a while does get an adrenaline flow.
I suggest we leave him and his build thread in peace, it is not worth anyone's time, neither you both's, his nor his followers.
There are billions of megabytes of misinformation floating in the web, are you both going to stop or question all of that?
Hello Yogibear !!
You judge the changes, in all locations, by listening to each AC orientation inside the amplifier individually. Now that I have explained what it is, and HOW to do the evaluation precisely in this thread, there is no need for you to bury your head in the sand .
There is no excuse NOT to do this, assuming you have a good, transparent, high efficiency system, well wired, to hear these differences. Your defeatist attitude will never bring you the permanent sonic gains possible.
Are you going to continue to DIY build equipment, ( in your perhaps favorite hobby ), for the rest of your life ( you tell us solid state next, later this year ) and NEVER ever hear any piece to it's optimum. ????? How much time, effort and money are you going to spend, for the rest of your life, and never optimize your amplifier builds ??????
The supplies go up and down in feed-voltages, but that does not preclude you at all from listening to one minute sections of demanding music, BACK and FORTH, over and over, until you decide what AC orientation sounds best !!! The total VAC is not fluctuating any wide percentage, during your A-B ing of this small one minute music sample,....... is it ???
Do not be a defeatist in your attitude.
I have shown you HOW to do it. You likely have a good enough system. Find out and apply this optimization to all your amplifier builds. It works on Solid State too. I did it ( along with Mil Spec wire leads ) on my two-transformer Bravura phono preamp, that Dr.Gary kindly repaired for me once. ( Which I now never use,...... after a Trevor Lees 12AX7 circuit instantly " ate " the Bravura preamp .)
Warning : If all the AC orientations are internally confused, the very first test ( the Input tube's filament ) will be the HARDEST to discern.
Why, because the amp is all AC " skewed " in it's playback. This skewing is particularly noticeable in SINGLE ENDED amplifiers, by the way, which is all I build these days. Once you check and correct the other AC orientations, and get the entire circuit UN skewed, you could go back, reverse the Input tube transformer's filament leads, and you will have an EASIER time hearing that first polarity difference.
This is just common sense experimenting. No college degree, or even advanced comprehensive E.E. knowledge is required at all to gain the fidelity improvement. You just must start with an open mind, and have the desire - to make something as good as it can be. You will have more FUN hearing it play back your favorite music. I do. It is called DIY.
If a person can not hear the difference, it is not because of (a) their hearing or (b) there is no difference. The problem is simply that their entire system is not revealing enough, and you now know !!
Jeff
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What those "special" clip leads actually do is to prematurely turn those GTO capacitors into indutors.Good Hari,
LOL, your original E.E. education is showing . Your answer is just not good enough - at all - for me !!
Do not allow your own pre-concieived notions keep you from TRYING, and most importantly, from finding out what the real truth is !!
It is time for you to FINALLY set the AC polarity, internally, for each of your monoblocks. YES, you DO have adequate hearing, IF you just A-B it properly. What is properly??
DO NOT use the usually-sourced cheapest possible long thin wire clip leads. Make up some Mil Spec clip leads, I use seven inch long 14 AWG m22759/11 wire lengths, and I use pure COPPER , unplated clip leads, readily available on line. See photo below.
Do the procedure precisely as I have reported above in this thread, and report back to us all.
Make notes, mark ONE lead of each AC connection with a indelible magic marker, so there is NO way to get polarity confused.
Play a digital recording of DEMANDING music and make sure you stop and start at the same spot each time. No longer than one minute of demanding program material. Back and forth, back and forth. Over and over again. Play it loud !! All you need to do is determine what orientation sounds best, remove the clip leads, SOLDER the wires into the circuit, and go on to the next spot in your KT88 SE amplifier.
In this thread's stereo 6005 amp, by ear A-Bing on music, I had to reverse four out of five locations. It was appreciably better, surprisingly so, once the work was performed. Maybe, subjectively, in my own home's transparent, well wired, high efficiency ALTEC VOTT A7-8 horn system, the amplifier became 5 to 8 percent better in overall fidelity.
No one in audio I am aware of ( except me and Dennis Fraker ) does this internal polarity AC polarity optimization Hari. I just started doing this in my mid-2019 KT88 build. This is well-beyond any normal EE's thought processing capabilities, ( due to their training ) as we can all see here in this thread............ BEAUTIFULLY . LOL. But it is what I hear, and hearing it undoubtedly solves the question completely !! One cannot deny the truth.
You have two mono amps, with TEN total locations to listen to, and optimize. Do it to one mono amp, and compare it against the other .
ONLY by doing this Hari, will you ever hear your amps at their best, and hear your amps properly Hari. !!
On almost every schematic I have sent you, I have made mention of individually aligning the AC phases of each transformer and it's associated windings.
It has not been done. No laziness. No EE-type mental blocks. No excuses.
Also, Hari, buy a proper sized stubby Phillips screwdriver, and REMOVE the Softone RW-20 Output transformer's stock steel covers !! Those steel covers on your R-Core output transformers alone, are about a 3% fidelity degrade !!!
If I can readily make such determinations - on this thread's 6005 stereo amp - in a few hours of A-Bing and re-soldering, ( with me being maybe 20 years older than you ) , you certainly can. But you certainly must TRY !!!
Jeff ....................................... Note my special clip leads below in photo, red and black insulators !! Very good amp :
View attachment 66542
RtoR King
Active Member
This is an appeal to the moderators to ban this trashing of anyone or any professional group a whole here. There is no need for these snide comments. I was able to post an eight paragraph insight to the AC plug polarity question without insulting anyone or any professional body. I also think I presented some good history and proven theory of one way this phenomena can happen, actually lending some supporting evidence that may explain some of Mr, Lowmu's empirical findings. That hardly seems to be narrow minded thinking.
I would like to suggest this be stopped or the thread once again closed and this time completely deleted thus preserving the good reputation of HFV.
RtoR King
Active Member
There is a type of line only regulator that may help your issue. It's simply a zener or gas tube in the base or grid of a pass device. This holds the incoming DC at a constant level but does not suffer from the feedback problems of a full line/load regulator. Note this is not a shunt regulator either. The zener or gas tube does not sense the load side directly, only the line side. Now if the unregulated DC source is not stiff enough, then the regulator will still tend to follow the load current and thus we again have a phantom secondary feedback loop. This idea would probably not work well with a tube rectifier.
Now how will this affect the sonics of the amplifier? I don't know but this would be an interesting experiment to try along with a full line/load regulator. Also you could regulate the AC line with a ferro-resonate transformer but be careful here. Most units produce highly distorted AC and those harmonics may get past your power supply filter bank. They do make clean sinewave units, which are also much more expensive.
I second that appeal to the moderators and respectfully request that other readers of this thread to do the same. Sometime back, I got my hand slapped by one of the moderators for engaging in what amounted to little more than a bit of hyperbole, all while Mr.Lowmu was engaging in lengthy, repeated anti-EE tirades and personal attacks that were insulting, antagonistic and abusive, and that contributed nothing of value to the topic of the thread, which is the build of an amplifier. Specifically, I call to the attention of the moderators the tirades by Mr.Lowmu in posts #305, #307, #314, and #320 which are all in violation of Forum Rules #1, #2, #5 and #6.
1-25-2022.................... Latest UPDATES ................. Chassis #2 Start-UP today - with 230 VAC INPUT
Today was the first full 230 VAC start-up of Chassis #2. The amp has a Shilchar 320 VA R-Core Main Power Transformer, ( 230 VAC input ) that Sadik and Hari were able to help me custom order. This is an amp custom built for a professional person in Hong Kong. He solicited me, and asked me to build for him " the best possible one Watt amp." for his Lowther Beauhorns. This newest 6005 amplifier is it, ...........except , it is more like 3 Watts.
I am pleased to report, everything went very well today, measurement VS all of 2021's development and planning that was done.
In a DC amplifier, all the resistor values interact with the circuit's voltages and tube operating points - a lot. I always take extra care in my designs, to get ideal operating points for each tube in these " favored " two-stage DC amps.
Also, I am always designing with conservative tube operating points, for maximum equipment reliability, long tube life, and the best possible long term sonics.
The 6005 tube's maximum plate-to-cathode ( P-K ) voltage is rated at 250 VDC and this vacuum tube's maximum rated plate dissipation is 12 Watts.
When it comes to plate dissipation of an output tube, I conservatively select nature's Golden Ratio proportion as the tube's design center ( to operate it ! ) , which is 62%.
This is not usually seen in tube audio. Designers tend to " hot rod " tubes to establish short term gains, marketing power-bragging rights, basically - all at the expense of the user's long term benefit.
That 62% Golden Ratio means operating the 6005 Output tube at a 7.44 Watts of power dissipation, for its' 12 Watt rated plate. How well did the new design measure today , VS:...... 62% ?? Excellently. One measured channel calculates at 61.02% and the other 60.79 % !
I was most satisfied with today's actual results.
Hari Iyer's SE DC KT88 output stage, ( which I originally designed in 2019 ) also operates for a number of reasons, ultra conservatively. As I recall, only at about at 31%, and he seems quite pleased. Usually, however, I am at 62% .
All the rest of the Chassis #2's measured voltages today were similarly VERY close to what I had simulated theoretically and calculated. NO resistor Ohmic value changes will be needed !!
In fact, about 95% of what was measured was within one or two percent of the schematic's design. The worst single measurement was +3.5%, and it was a) in the "right" direction and b) not in a critical spot. TUBES themselves also vary in a circuit - by a certain percent.
One other comment is apropos. I agree with RtoR King's critique today, but certainly not his drastic suggestion. It is simple for me to resolve.
Henceforth, I will make no snide remarks about E.E. trained people, although it did fit Hari to a tee in this instance, and he even gave it a thumbs up. Nor will I refer to any other of the E.E.s, or E.E. types, in a similar manner. I certainly do have good respect for some ( not all ) E.Es, including certain HFV FMs - with such training.
My posts, my perspective, and my audio builds are unique, and no one I know of, in the audio world, except my audio mentor and me, builds like this.
I have news for you all, after a few weeks of listening seriously, on a good system, I am also of the opinion, no one has a tube amp that will perform nearly as good as this new 6005 design. It is about time - I told you that.
No, I am not being arrogant here !! I am totally truthful with you, to my best recent direct listening experiences and moral compass. This initial opinion can subject to revision, of course.
Holy smokes !!! The new amp is doing phenomenal things with music's playback !!!
" Impeccable timing, total resolution, all at once, of multiple / simultaneous / and differing instruments, with dynamic contrasting beyond compare - is precisely what I hear. "
The above sentence is my best way to subjectively describe it's performance. ie : " How does it play back musical instruments ?????? "
In late February, the 120 VAC Chassis #1 amplifier will hopefully be compared to a friend's amps' - his Japanese 300B deluxe stereo amp and his German 845 Thoress monoblocks. I will try to get HIM to do the report of the A-B sessions, once we get the time and opportunity to get together to do these evaluations.
This is only about 3 Watts, so it is for 100+ dB speakers. I have a more usable " triple " 6005 SE amplifier on the drawing board, ( nicely employing this 6005 Thread's design concepts ), as I type this post !
Regards,
Jeff
Today was the first full 230 VAC start-up of Chassis #2. The amp has a Shilchar 320 VA R-Core Main Power Transformer, ( 230 VAC input ) that Sadik and Hari were able to help me custom order. This is an amp custom built for a professional person in Hong Kong. He solicited me, and asked me to build for him " the best possible one Watt amp." for his Lowther Beauhorns. This newest 6005 amplifier is it, ...........except , it is more like 3 Watts.
I am pleased to report, everything went very well today, measurement VS all of 2021's development and planning that was done.
In a DC amplifier, all the resistor values interact with the circuit's voltages and tube operating points - a lot. I always take extra care in my designs, to get ideal operating points for each tube in these " favored " two-stage DC amps.
Also, I am always designing with conservative tube operating points, for maximum equipment reliability, long tube life, and the best possible long term sonics.
The 6005 tube's maximum plate-to-cathode ( P-K ) voltage is rated at 250 VDC and this vacuum tube's maximum rated plate dissipation is 12 Watts.
When it comes to plate dissipation of an output tube, I conservatively select nature's Golden Ratio proportion as the tube's design center ( to operate it ! ) , which is 62%.
This is not usually seen in tube audio. Designers tend to " hot rod " tubes to establish short term gains, marketing power-bragging rights, basically - all at the expense of the user's long term benefit.
That 62% Golden Ratio means operating the 6005 Output tube at a 7.44 Watts of power dissipation, for its' 12 Watt rated plate. How well did the new design measure today , VS:...... 62% ?? Excellently. One measured channel calculates at 61.02% and the other 60.79 % !
I was most satisfied with today's actual results.
Hari Iyer's SE DC KT88 output stage, ( which I originally designed in 2019 ) also operates for a number of reasons, ultra conservatively. As I recall, only at about at 31%, and he seems quite pleased. Usually, however, I am at 62% .
All the rest of the Chassis #2's measured voltages today were similarly VERY close to what I had simulated theoretically and calculated. NO resistor Ohmic value changes will be needed !!
In fact, about 95% of what was measured was within one or two percent of the schematic's design. The worst single measurement was +3.5%, and it was a) in the "right" direction and b) not in a critical spot. TUBES themselves also vary in a circuit - by a certain percent.
One other comment is apropos. I agree with RtoR King's critique today, but certainly not his drastic suggestion. It is simple for me to resolve.
Henceforth, I will make no snide remarks about E.E. trained people, although it did fit Hari to a tee in this instance, and he even gave it a thumbs up. Nor will I refer to any other of the E.E.s, or E.E. types, in a similar manner. I certainly do have good respect for some ( not all ) E.Es, including certain HFV FMs - with such training.
My posts, my perspective, and my audio builds are unique, and no one I know of, in the audio world, except my audio mentor and me, builds like this.
I have news for you all, after a few weeks of listening seriously, on a good system, I am also of the opinion, no one has a tube amp that will perform nearly as good as this new 6005 design. It is about time - I told you that.
No, I am not being arrogant here !! I am totally truthful with you, to my best recent direct listening experiences and moral compass. This initial opinion can subject to revision, of course.
Holy smokes !!! The new amp is doing phenomenal things with music's playback !!!
" Impeccable timing, total resolution, all at once, of multiple / simultaneous / and differing instruments, with dynamic contrasting beyond compare - is precisely what I hear. "
The above sentence is my best way to subjectively describe it's performance. ie : " How does it play back musical instruments ?????? "
In late February, the 120 VAC Chassis #1 amplifier will hopefully be compared to a friend's amps' - his Japanese 300B deluxe stereo amp and his German 845 Thoress monoblocks. I will try to get HIM to do the report of the A-B sessions, once we get the time and opportunity to get together to do these evaluations.
This is only about 3 Watts, so it is for 100+ dB speakers. I have a more usable " triple " 6005 SE amplifier on the drawing board, ( nicely employing this 6005 Thread's design concepts ), as I type this post !
Regards,
Jeff
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Wouldn't having an external stabilizer for whole house or just the AV setup assure steady voltage and mains frequency?
Cheers,
Raghu
1-26-2022 ........................Things to be Done...................................Break In ..............
Its pretty simple going forward. Chassis #2 did well, with yesterday's six hour initial " 230 AC " operating time.
Brand new parts need to be broken in.
As examples : The J.J. 5U4GBs sound good with 75 hours on them, as do the two Hammond Main 159ZA power supply chokes, ( to eliminate a 159ZA's initially-only, subtle recessed-midrange. )
The Japansese Softone R-Core SE Output Transformers, require a very lengthy break in. After 100 hours, you get an " idea" of what they are like, but it really takes up to 800 hours to fully blossom into their maximum most-acceptable fidelity. All Softone transformers also will sound best with their fancy steel covers removed !! A great tweak !!
A break-in plan is to hook up Chassis #2 ,( with the amp being fed a full 230 VAC ), to a spare CD player and play a music CD " on repeat " for about two to three weeks. The amp will be put through numerous full-on, full-off, rest and cool-off thermal cycles, This is a practical way to break it in, and put many many hours of music playing on it.
Additionally, there will be 8 Ohm Power Resistors, attached to the CARDAS output jacks, so the output transformers have a ( silent ) load upon them, in lieu of loudspeakers. LOL, while I am retired and asleep for the night, the amps can be playing music, full bore - silently !
After several hundred hours of break in / cycling are accomplished, I will then take the time and properly align the amp's several internal AC orientations by ear, exactly as described in this thread ( using " Solo Drums " Steve Clarke ). Then, carefully pack and ship the unit to Hong Kong, with m22759/11 speaker wiring, for use on Lowther Beauhorn Virtuosos. See :
.
You can find out about this ( rear and partially front ) horn loaded speaker, including several fine photos, at :
http://www.glowinthedarkaudio.com/lowtherbeauhorn.html ...................... Enjoy !!
This thread's new 6005 amp has turned out to easily better any other amplifier I have ever personally made, or can even recall hearing, by seemingly - a very wide ( over 20% ) margin. I am confident this new 6005 amplifier will be a superb match, and appreciated in Hong Kong - on Beauhorn Virtuosos.
Jeff
Its pretty simple going forward. Chassis #2 did well, with yesterday's six hour initial " 230 AC " operating time.
Brand new parts need to be broken in.
As examples : The J.J. 5U4GBs sound good with 75 hours on them, as do the two Hammond Main 159ZA power supply chokes, ( to eliminate a 159ZA's initially-only, subtle recessed-midrange. )
The Japansese Softone R-Core SE Output Transformers, require a very lengthy break in. After 100 hours, you get an " idea" of what they are like, but it really takes up to 800 hours to fully blossom into their maximum most-acceptable fidelity. All Softone transformers also will sound best with their fancy steel covers removed !! A great tweak !!
A break-in plan is to hook up Chassis #2 ,( with the amp being fed a full 230 VAC ), to a spare CD player and play a music CD " on repeat " for about two to three weeks. The amp will be put through numerous full-on, full-off, rest and cool-off thermal cycles, This is a practical way to break it in, and put many many hours of music playing on it.
Additionally, there will be 8 Ohm Power Resistors, attached to the CARDAS output jacks, so the output transformers have a ( silent ) load upon them, in lieu of loudspeakers. LOL, while I am retired and asleep for the night, the amps can be playing music, full bore - silently !
After several hundred hours of break in / cycling are accomplished, I will then take the time and properly align the amp's several internal AC orientations by ear, exactly as described in this thread ( using " Solo Drums " Steve Clarke ). Then, carefully pack and ship the unit to Hong Kong, with m22759/11 speaker wiring, for use on Lowther Beauhorn Virtuosos. See :
.
You can find out about this ( rear and partially front ) horn loaded speaker, including several fine photos, at :
http://www.glowinthedarkaudio.com/lowtherbeauhorn.html ...................... Enjoy !!
This thread's new 6005 amp has turned out to easily better any other amplifier I have ever personally made, or can even recall hearing, by seemingly - a very wide ( over 20% ) margin. I am confident this new 6005 amplifier will be a superb match, and appreciated in Hong Kong - on Beauhorn Virtuosos.
Jeff
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How about a small solar system that is dedicated to powering only your audio system with a stable AC voltage?
@yogibear why not on a heavy duty voltage stabilizer. Is that not the simplest and safest solution in areas with such high incoming voltage or fluctuation. In fact I would recommend a 5 to 10 KVA solution and put it on the mains. It will increase the life of all the electrical and electronic equipment other than ofcourse geysers and air conditioners which will offer high loads.
Would be worth its weight in gold, especially taking into account the cost of the gears you make. Most importantly peace of mind.
I have a vintage one which an electrical engineer told me is built exceedingly well. Tried it some years back and somehow liked the sound without it. Will pull it off the loft on Sunday and give it a go again.
I had actually put in on giveaway 2 years back, and there were no takers. Maybe it was for my own good.
here is the ugly duckingI have a vintage one which an electrical engineer told me is built exceedingly well. Tried it some years back and somehow liked the sound without it. Will pull it off the loft on Sunday and give it a go again.
I had actually put in on giveaway 2 years back, and there were no takers. Maybe it was for my own good.
...1KVA
Yogibear,
Thus high VAC line came about the past 20 Months or so in India, as COVID shut down businesses, and the lower overall electricity use raised the VACs at the wall, considerably. Hari was reporting this to me all last year, with his mono blocks.
It is a very poor idea for end-users to be switching Mains Voltage Taps, and adding complexity, un needed, to your DIY build IMHO. Simply " Design center " your amps to take such VAC swings into account !!!
No user adjustments in an amplifier is the superior way to design any amplifier, IMHO !! I do this always.
You need to change your way of selecting and specifying transformers.
The best Power Transformers will have the lowest DCR and be WAY overbuilt, to obtain a combination of reliability, and superior sound.
When WE had SHILCHAR build Hari Iyer's R-Core power transformers in 2020, we needed to power two mono amps with about a 80 mA. total load, for each amp. With me specifying Direct Coupling, we needed about an 800 VCT power transformer. What is that ? 64 VA per mono block I suppose. ( 0.080 A. times 800 VCT )
We specified for Shilchar to START with a 320 VA sized R-core, to do their winding.
Hari had it speced as 800 VCT at 400 mA. or maybe even 450 mA. as I recall. Having a 400 mA. Power transformer doing 80 mA. continuous, is a breeze !!
It is five times over speced. ' Never gets very warm. R cores have a low radiated field also. This conservative spec results very beneficially in low DCR across the entire High Voltage winding ( 70 Ohms as I recall , end to end - please measure and report yours !! ). Each unit runs cool and loafs.
Recall my State of Missouri / USA car license plate ( personalized ) ?? ....................... It is ............." LOW DCR ".
The audio amplifier starts with the power supply, and the power supply starts with the power transformer. Intelligently select it. I saved a personal letter , written to me in about 1989, from the Dean of the College of Electrical Engineering, at the University of South Carolina, USA, about Power supplies. use it as your theoretical guide in amp building !! Dr. Charles A. Halijak . The letter to me is entitled " The Figure of Merit in a Power Supply " :
1989
Dear Jeffrey,
This letter is concerned with the power supply and the use of chokes.
A choke must have some internal resistance and its non-standard figure of merit is the ratio R over L. The best choke is the one with the smallest figure of merit and the best power supply has the least series resistance. It is not too difficult to obtain R over L = 10 but one can easily obtain R over L = 30 or more. The latter should be avoided but the ongoing shows that in a way it is unavoidable.
The choke input filter controls the diode by timing and not by ohmic losses. ( jm: current vs: voltage waveforms) The best place for a choke is at the input and the worst place is at the other end of a power supply filter chain because resistances tend to be higher there.
Suppose we start with your case and R over L = 10. When diode ( 5U4GB) and transformer resistances are taken into account we have :
15 ( choke ) + 70 ( rectifier ) + 70 ( power transformer resistances )
------------------------------------------------------------------- = 103
1.5 ( HY )
( the 70 ohm power transformer resistance is a guess )
If four 5U4GB are placed in parallel one has :
15 + (0.25 ) ( 70 ) + 70
__________________ = 68
1.5
Both figures of merit are way above the original 10 but your listening experiment told you that 68 was alright; this actual figure of merit is the best you can do because the largest power transformer was used and the smallest resistance available choke was used. You can see that stock power supplies are not anywhere near being the best cases.
* Most tube and transistor electronic engineers are unconscious about power supplies, but good.
* Also the best cases need not have zero internal resistance - a utopian goal. One strives for minimal non-zero resistance !!
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Jeff here :
I want to emphatically point out, that E.E. Dean Halijak's next to last sentence right above ( the first one stared ) are his words in 1989, unsolicited, .....and NOT mine ( in light of my recent promise to this Forum .)
A highly unusual comment ......... coming from the Dean of E.E .
Well, now you all have one clue as to why Dennis Fraker and I uniquely use choke input filters, with two SIX Ohm DC Resistance chokes, and enjoy the hell out of the sonic results. No one else does this.
LOW DCR is ALL part of this thread, very clearly disclosed by me on Page One. Recall ??? When I switched from two ten Ohm power supply chokes to two SIX Ohm chokes, as the ten Ohm chokes didn't cut the mustard.
New Design, SE 6005 Directly Coupled Audio Amplifier
This is a current design and build project, a DIY hobby of mine for many years. It uses a 6005 FINALS tube, which has a 10 Watt (correction - 12 Watt) plate dissipation, and was introduced in the 1950s. Used in car radios and TVs as the FINAL stage, in the USA and in Russia ( an equivalent )...
www.hifivision.com
Fun, huh ? !! I hope some people are starting to see the light, and learn what is important .
As a minimum Yogibear, I would recommend using a Power Transformer at no more than half of it's VA rating. But you can see, Hari 's is operating at 20%, one fifth, as per my influence.
Jeff
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