Operational as of 12-01-2016.
See it on Audio Asylum Forum, Tube DIY Audio : Here :
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Thank you for looking.
Jeff
See it on Audio Asylum Forum, Tube DIY Audio : Here :
Audio Asylum Thread Printer
Thank you for looking.
Jeff
I am not sure why you are so proud of the low DCR of those small chokes you used (with small caps as well)....
Yes, it s new to you...no problem. To be expected.
There are two things you can do to educate and inform yourself as to WHY I do what I do.
The easiest is to write to me at drlowmu@gamil.com, and ask me to send you back ( via email attachments ) the Power Supply Compilations from EEs Swenson and Hasquin. That will get you a great start of total understanding.
Next, since you are in the UK, I have a friend who USES just such a supply on his Avantegarde Horn speakers in London. He uses EML 45s as Finals in his DIY amp.. You can bring your amps over to his place, and A-B them, versus what he built. Then, you will totally understand.
Jeff
Education and information is likely to make people more puzzled about why you do what you do - provided, of course, that the education is about electronics. That amp appears to be designed to push certain audiophile buttons, and exhibit certain audiophile myths. Fine if that is what you set out to do. Each to their own.drlowmu said:
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Hi,
When you use a single power transformer, shared by left and right channels, there are audible "artifacts" that are added to the one channel, from the operation of the other channel.
This sorta " fills in " the middle midrange, and it adds a " fullness" that people with less efficient speakers may prefer. But on high sensitivity speakers, and ***/U/ME we have a good SET amp, the use of a separate supply for each channel brings an immediate CLARITY, a pristine clarity, that you can NEVER get with a shared channel power transformer - ever !!
I have heard this clarity, every year for three days for the last ten years at Denver RMAF shows, with Dennis Fraker's Serious Stereo monoblocks. I heard it this October 5-8th for three solid days in Denver, helping Dennis run his demo room.
Bigun, as SOON as I fired up mt new DUAL MONO SET on 12-01-16, I heard this same uncanny sense of clarity, for the FIRST TIME in my OWN listening room, on my VOTT A7-800s !! Goodness, I LOVE it now. The more complex the music, the more I notice this, in my own listening room, and the MORE I am liking it.
So, I am "spoiled for life" now, either monoblocks or dual-mono stereo amps, from now on.
If the SET amp is less than perfect, ( 99% are less, 90% are JUNK ) then maybe you wanna add those midrange artifacts to fill-in the poor SET amplifier execution. Never again for me, as of 12-01- 2016 !! I love hearing the clarity, WOW. What a pleasure.
Jeff
No it's not. My point was that you are so proud of the low DCR of your chokes but you have a couple of huge resonances well inside the audio range and so the supply has quite HIGH impedance well across the bass region, assuming you use 50 uF caps. If less than 50 uF even worse.
This stuff is pre-history for me. I just made a technical point.
My main stereo system (which is in Italy unfortunately) includes the ROOM, of course. It's a CLOSED system. If you come this way let me know....
A-B comparisons in RANDOM fashion are just a waste of time....
Dear 45,
LOL !! Quoting you :
"you have a couple of huge resonances well inside the audio range and so the supply has quite HIGH impedance well across the bass region, assuming you use 50 uF caps. If less than 50 uF even worse. "
- - - - - - - - - - - - -
Yes !! Whatever you do, do NOT ask for the compilations, because you will discover your highly-erroneous thinking.
The ones who squeel the most up here, I will guarantee you all, have never read the compilations.
Also for sure, none of these nay sayers have ever heard this supply, executed properly in a SET 2A3 amp, so they speak from ZERO actual / practical experience with this.
I wish you all well and have a good day.
Jeff
LOL !! Quoting you :
"you have a couple of huge resonances well inside the audio range and so the supply has quite HIGH impedance well across the bass region, assuming you use 50 uF caps. If less than 50 uF even worse. "
- - - - - - - - - - - - -
Yes !! Whatever you do, do NOT ask for the compilations, because you will discover your highly-erroneous thinking.
The ones who squeel the most up here, I will guarantee you all, have never read the compilations.
Also for sure, none of these nay sayers have ever heard this supply, executed properly in a SET 2A3 amp, so they speak from ZERO actual / practical experience with this.
I wish you all well and have a good day.
Jeff
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Don't need your compliations. A LC circuit has a resonance by DEFINITION. It's just a matter of where this is located and which merit factor it has.
It might sound pleasant to you probably because it makes other mistakes or big flaws in your system more acceptable. I am sure your speakers are flawed as are 99% of high efficiency speakers.....including Avantgarde!😀
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I can imagine that with a SET, the PSRR is naturally quite low and so the power supply needs to be very carefully implemented to avoid cross-channel effects. I guess it's possible to minimize this whilst using a single transformer, but the steps you'd take may not be compatible with your LSES approach. But it's rare that folk post their subjective findings from using dual-mono. For SS amps with feedback PSRR is usually very high and a single transformer makes more sense because they are generally more efficient. Keep sharing your ideas - all interesting info to be stored away for future use 🙂
I'd agree, and if using dual transformers makes a difference I'd say they were still in the signal path.
Jeff,
I, too, have found dual mono from phono to power amplifiers is superior.
David MANLEY was a proponent of this and would readily say he was not sure why it does what it does but it's there for those with ears to hear. John Broskie brings this up in one of his recent blog posts. He tells of his own experience and the conversation he had with Mr. Manley.
This place does have a continuing battle between those who see DIY audio as a cookbook with recipes that must be followed to the letter or you will blow up your oven and a few who are willing to try things and hear what happens.
I know you did not come upon these ideas in a dream. There is a long continuum of trials of many people that came to this conclusion.
How does one remove the power transformer from the signal path? I know you could simply disconnect it but the the thing would not work then.
I, too, have found dual mono from phono to power amplifiers is superior.
David MANLEY was a proponent of this and would readily say he was not sure why it does what it does but it's there for those with ears to hear. John Broskie brings this up in one of his recent blog posts. He tells of his own experience and the conversation he had with Mr. Manley.
This place does have a continuing battle between those who see DIY audio as a cookbook with recipes that must be followed to the letter or you will blow up your oven and a few who are willing to try things and hear what happens.
I know you did not come upon these ideas in a dream. There is a long continuum of trials of many people that came to this conclusion.
How does one remove the power transformer from the signal path? I know you could simply disconnect it but the the thing would not work then.
It depends how you wire your stuff.
When i mute one channel input and other one is playing, muted channel is still quiet.
Hi,
You comment above with these words : " but the steps you'd take may not be compatible with your LSES approach.".
I do NOT understand why you say this? If anything, separate dual mono, or better yet , two monoblocks are TOTALLY compatable with a LSES supply.
Remember, it was Dennis Fraker in Montana USA, who, in 1989, invented and executed the L.S.E.S . ( low stored energy supply ) in his Serious Sterero 2A3 SET DC amp prototype, and his first builds.
If anything, Bigun, it is actually far far EASIER to apply LSES to a dual mono, or separate monoblock execution. Why? The Filter to the Finals only needs to see the current of just ONE channel, typically a Finals 2A3 stage at 43 to 44 mA., plus the Driver Stage at about 10 mA..
It is far easier to filter 54 mA. ( 44 + 20 ) than two channels 108 mA., through a B+ L1/C1/L2/C2 LSES filter - with smaller value chokes, and small-as-possible caps. That should make sense to you, and it is counter to what you previously posted, that I pointed out above.
Hello Rick,
I have never read Manley or Broskie. About a month ago, I posed the "one versus two power transformer" question to my mentor, Dennis Fraker, who designs and builds the Serious Stereo 2A3 monoblock amps.
Dennis strongly advised me to use two power transformers, one for each channel, explaining I would get a CLARITY on my ALTEC Horn system, that I can not get with a single ( shared L-R ) power transformer. So, at the last moment, I switched my design and supply to dual mono.
I am SO HAPPY I did this, Rick !! I have put 12 hours on the amp's break-in process ( usually needs 50 hours to get in the ball park ) and ALL that I hear so far, on familiar program material, has HIGHLY reinforced my newest belief. NEVER build a stereo single power transformered amp again - at least for myself. Live and Learn. Thank you, Mr. Dennis Fraker at Serious Stereo !!
Jeff Medwin
Naming a wimpy power supply design and calling it an invention is more than a stretch. I find it impossible to believe that such an "invention" to be so new and earth shattering that the rest of the planet completely missed it over the past century, i.e., if it sounds too good to be true, it certainly is.
The real world problem with this approach should be obvious. As the power supply admittedly has little stored energy, it has little ability to handle dynamic transients via supply loading. With a single-ended design, the current draw from the supply constantly changes proportionately with the audio signal. This will not be a linear function with frequency, as the chokes and capacitors in the filter will have a resonant frequency and will interact with amplifier performance.... and NOT is a positive way.
Such a supply would, in theory, be better suited for a push-pull Class-A design as the actual current draw would (again in theory) be constant as one side of the circuit increases current use as the other side decreases. Still, as the program material contains low frequency content that is down around the resonance of the supply filter (and even worse, frequencies below that resonance), it will still have a negative impact on performance.
Based on the above conditions, I would certainly expect you to hear a difference using separate supplies for each channel, as the impact to the power supply is halved.
If you're convinced such an implementation is superior, there's a fairly simple test, scope the power supply B+ with AC coupling and watch the B+ signal under normal operating conditions. If the signal remains stable, you have an adequate supply. If the B+ signal fluctuates with the program material signal, you have a poor supply.
Regards, KM
The real world problem with this approach should be obvious. As the power supply admittedly has little stored energy, it has little ability to handle dynamic transients via supply loading. With a single-ended design, the current draw from the supply constantly changes proportionately with the audio signal. This will not be a linear function with frequency, as the chokes and capacitors in the filter will have a resonant frequency and will interact with amplifier performance.... and NOT is a positive way.
Such a supply would, in theory, be better suited for a push-pull Class-A design as the actual current draw would (again in theory) be constant as one side of the circuit increases current use as the other side decreases. Still, as the program material contains low frequency content that is down around the resonance of the supply filter (and even worse, frequencies below that resonance), it will still have a negative impact on performance.
Based on the above conditions, I would certainly expect you to hear a difference using separate supplies for each channel, as the impact to the power supply is halved.
If you're convinced such an implementation is superior, there's a fairly simple test, scope the power supply B+ with AC coupling and watch the B+ signal under normal operating conditions. If the signal remains stable, you have an adequate supply. If the B+ signal fluctuates with the program material signal, you have a poor supply.
Regards, KM
Yes. 1.4H and 40uF give a resonance around 21Hz, giving a high PSU output impedance around this frequency. Choke resistance of 6R means a Q of 30. Now the rest of the circuit will modify this, but it would be hard to design a worse position for a PSU resonance. Hardly surprising that there would be considerable interchannel crosstalk if two channels were forced to share such a supply! The lesson to draw from this is not that separate supplies are needed; it is that well-designed supplies are needed. Many people struggle with a subsonic resonance in an LC supply (which can be at similar frequencies to music envelopes); the solution is definitely not to move the resonance up into the audio band.45 said:
There seems to be little point in having such low DC resistance in the chokes (and so suffering a high Q LF resonance) when the low capacitance of the PSU means that it will have high impedance anyway. A reservoir cap of 20uF fed full-wave at 60Hz has an effective DC impedance of 208 ohms. I guess having designed a high DC impedance you didn't want to make it even worse so needed low impedance chokes?
I must admit, the under-chassis view looks pretty - but electrons don't appreciate this.
Hello KM,
Nice to meet and hear from you. Its a shame you have never read about this type of LSES supply, or ever hard an amp properly using it.
YOU, and everyone one else who has " book training" has NOT conceived the all the things that are happening in a power supply feeding a 2A3 PROPERLY.
The lack of imagination amongst MOST ALL engineers, and their route reliance on 100 year old texts, theorems, floors me and makes me giggle. Can a modern engineer design something innovative and appropriate to play music - at a high level. So far, from what I see amongst the nay sayers, and most ( 98%) of the world, the answer is NO .....F minus in a grade, F- - in imagination and inventiveness. Most SET amps I see and hear are pure JUNK. Laughable, - not honest to the music - and in THAT way, I tend to agree with DF96.
You, and ALL the nay sayers are neglecting to consider the behavior of capacitors, especially in relationship to the 2A3 Finals tube, under DYNAMIC conditions !!
I appreciated your even handedness in responding to this post. It showed a heap of maturity. I would kindly like to send you these compilations to read, done by a couple of audiophile EEs, about eight years ago. After reading them, contact me please and TELL me what you think !! It will be very instructive for you, and will likely change your thought process, and the way you look at power supplies, for the rest of your life. Others won't even READ the compilations, but I sense you are coming in here at an even-handed and higher level. My email address is posted elsewhere in this thread.
Wishing you all well, and a Merry Christmas.
Jeff Medwin
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