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In Reply to: RE: Great Post !!!! posted by drlowmu on January 09, 2015 at 12:10:59
My PT is not 65 Ohms to center tap as your simulation shows, there is no hump and not that the hump is even relevant.
I have 30H 220 ohm chokes on the bench right now, shouldn't be hard to find.
As it has been explained to you, the part of the Sim that is relevant is the is the beginning.
The rest of the Sim shows a steady state draw on the PSU, which isn't whats happening with an audio signal.
Try again.
Follow Ups:
GG,
Ohh my goodness, I now do see you are using 165 Ohms, and I "saw" the "one" in one sixty five as a "parenthesis" on my small monitor. My visual error. Are you suggesting 1/2 your HV secondary is 165 Ohms?
As for this " As it has been explained to you, the part of the Sim that is relevant is the is the beginning."
That is incorrect, you have the "beginning" bass ackwards, the drop in the first 50 mS. is GOOD to be sharp and get "most" of the settling done smoothly and quickly as possible.
I will re-PSUD2 with 165 Ohms. BTW, That 165 Ohms PT DCR is a LOT worse than 65 Ohms. It WILL however, damp the waveform, and make EVERYTHING go in slow, out-of-time motion. Now, I'll go back to PSUD2 with 165 Ohms DCR, yikes !!
Jeff Medwin
"That is incorrect, you have the "beginning" bass ackwards, the drop in the first 50 mS. is GOOD to be sharp and get "most" of the settling done smoothly and quickly as possible."
I disagree with this, you want to hold as much voltage in the beginning as possible.
The sharper the drop, the more voltage you have lost, as in your case.
A shallow drop on the other hand delivers a stronger leading edge to transients because it holds a higher voltage for a longer period of time.
Remember transients are gone as quickly (aside from residual decay) as they arrive, so I fail to see why you are so concerned with what is happening a half second later on a simulated resistor.
A step drop off means you have less power when you most need it.
A fast charge time is nice, but doesn't mean much if you don't have the immediate capacity when needed.
It's the area under the curve that is important.
Have a look below, you tell me which one sounds better.
Your approach:
Or mine:
gargoyle -what happens if you extend out beyond 4 seconds and allow the 150uf cap to discharge?
I *think* the idea is that the low storage supply would recover from overload faster. it's hard to see that in a small window of time.
yes it drops 1 or 2 volts faster than the supply with more henries and capacitance, but also recovers faster. the other thing is the belief that while the 150uf capacitor is sinking current to recharge the output tube is starved for current, whereas the smaller caps won't have so much of an effect.
I think another issue here as the simulations get more elaborate, it's hard to nail all the variables for an accurate simulation.
the document that jeff speaks of, where he put all of the JLH posts he found that reinforces his power supply ideas, is VERY good IMO.
at some point if you guys are really curious, spend the $50-$100 on some chokes, mock up the supply and get your test gear out.
I'd recomend the flywheel stuff over this more recent power supply...
the stuff to use that is proven is the triad c56u and 2 stages of triad c40x.. hammond 159za is a bit better than triad c40x but costs about double.
three stages, .035h, 15uf, .3h, 50uf, .3h, 50uf
very low dcr toroid transformers where used by JLH. he got his "dynamic impedance" down to around 78 ohms with cree diodes in a bridge. not 650 ohms, he'd call that junk. 200-250 ohms with tube rectifiers.
he also did test with a frequency generator and found very little change in b+ across the frequency range, and was satisified with supply impedance at that point.
Jeff's got the document, and I think its worth a read. goes WAY beyond Jeff's interpretation..
I wonder how all the odd TW/DLM power supply configurations affect IMD measured at the output of the amp?
ARTA has a few preset 2 sine tests and a user defined option.
Have you played around with any of those measurements?
"gargoyle -what happens if you extend out beyond 4 seconds and allow the 150uf cap to discharge?"
-For curiosity sake I will see what I can do.
"I *think* the idea is that the low storage supply would recover from overload faster. it's hard to see that in a small window of time."
-I still fail to see the value in a fast charge time if it sounds bad during use.
Don't forget that the B+ voltage will be wildly swinging up and down simultaneously for the higher frequencies. This undulating reference will inter-modulate with the higher frequencies garbling the sound.
"yes it drops 1 or 2 volts faster than the supply with more henries and capacitance, but also recovers faster. the other thing is the belief that while the 150uf capacitor is sinking current to recharge the output tube is starved for current, whereas the smaller caps won't have so much of an effect."
-As I mentioned on the other page, it is the area under the curve that counts.
Capacitance fills in the dip. "starved for current" is kind of a red hearing, the tube will prefer to pull the current from the last cap anyways. It does not compete with the capacitor, it attempts to empty it.
So long as the voltage is higher then then ground, voltage will flow from the capacitor.
Farkwin supplies aren't "fast", they are saggy.
Those step vertical waveforms are there because it dropped like a stone and there is nothing to charge.
"Fast" would imply you had a transformer rectifier combination that could deliver much more current then typical devices used.
Since the Farkwin uses a tube, and usually the cheapest iron this isn't the case.
"I think another issue here as the simulations get more elaborate, it's hard to nail all the variables for an accurate simulation."
-It's OK if the results are somewhat arbitrary. We are comparing topologies.
"the document that jeff speaks of, where he put all of the JLH posts he found that reinforces his power supply ideas, is VERY good IMO."
-I've read too many ridiculous things claimed by Drlomu over the years to go chasing unicorns.
"at some point if you guys are really curious, spend the $50-$100 on some chokes, mock up the supply and get your test gear out."
-I've read too many ridiculous things claimed by Drlomu over the years to go purchasing unicorns.
Don't forget the humble PC is a pretty good piece of test equipment as demonstrated by this thread.
"I'd recomend the flywheel stuff over this more recent power supply... "
-Sounds catchy!
"three stages, .035h, 15uf, .3h, 50uf, .3h, 50uf
very low dcr toroid transformers where used by JLH. he got his "dynamic impedance" down to around 78 ohms with cree diodes in a bridge. not 650 ohms, he'd call that junk. 200-250 ohms with tube rectifiers."
-Seems like a lot of fuss to try and compensate for low capacitance, not to mention noisy.
"he also did test with a frequency generator and found very little change in b+ across the frequency range, and was satisified with supply impedance at that point."
-Good for him.
I don't think Drlomu should drag someone into the mud based on some half assed implementation of something he read somebody else do.
I'm no EE, but I don't think the term "Dynamic Impedance" is being used properly, or is even relevant beyond the application cited.
A quick look at yesterdays sims show the voltage wavers steady after the rectifier. Dynamics seem to be pulled from the caps which seem to be much lower then the "78 ohms" you implied to be a good number.
Everything has trade-offs. My preference for power supplies are slow to charge at turn on.
This is a good compromise because the tubes are warming up anyways.
Slower to charge is also slower to drain which equals a longer amount of time closer to the optimal B+, much stiffer too.
To justify your VERY misguided intellect .
Edits: 01/12/15 01/12/15
Jeff, it is hard at times to figure out quite what it is that you believe. You surely must agree that the output voltage of your low C, low L power supply fluctuates more with the audio signal than a high C, high L supply will do? Is this, at least, an area of common ground between what you are saying and what many of the rest of us are saying?
If you want to argue that despite fluctuating more, or indeed perhaps because it fluctuates more, it "keeps better time with the music," then that could be a separate discussion. (I don't know what "keeps better time with the music" is supposed to mean, but still, that is a discussion one could have.) But the fact that small C and L will cause a greater level of fluctuation at the audio frequencies can surely not be in dispute?
Chris
The stiffer a power supply is--- that is, the less it current-starves the amp stage it is powering, the better it will follow the "groove" of the music. It is IMPOSSIBLE, therefore, to follow the music's groove with a power supply that fluctuates (sags) enough to momentarily current-starve any amp stage that it is powering.Current starvation can come from several sources:
(1) Capacitors that store too much energy and release it too slowly. The cap's re-charge cycle takes current away from what is to be powered, and the release cycle of a large cap simply doesn't even get started (release isn't fast enough) until the musical transient has come and gone.
(2) Current starvation can come from a power transformer that's operated too close to its rating. Run about 30% of the rating, or less.
(3) Current starvation can come from too much stored inductance in chokes-- as in capacitors-- energy charge-up hogs current away from the device to be powered and energy release is delayed for too long.
(4) Current starvation can come from unnecessarily high resistances in the wrong places. These can be high-DCR chokes (anything over 20 ohms in most cases in tube amp power supplies).
(5) Current starvation can come from attaching devices onto the plate or cathode of a tube, in the attempt to correct for a sagging power supply. Examples of this include CCS devices, SRPP, etc., and several more.
(6) If a current-starving (under powered, or slow due to large capacitors, high value chokes, etc.) power supply is being operated, use of these (above) correction devices will usually improve bass performance at the expense of causing some current starvation of High notes that are extended and extremely dynamic, such as repeated cymbal clashes-- something very few amps ever get right-- so no one should feel bad if he's never heard an amplifier do it right. The use of these add-on devices nearly always also cause slight-- or sometimes worse-- degradation of signal purity, similar to a Tetrode or a Pentode VS a true triode-- that is-- slight signal homogenization and slight (or worse) image smearing.
The above effects (defects, actually) are euphonic and pleasing to many listeners because by homogenizing some signal information together, they more fully "flesh-out" the music-- it sounds solider and fuller than it actually is. This problem largely disappears with the use of medium or lower-efficiency speakers (usually under 96 db/watt) simply because those speakers can't reproduce it, but becomes apparent as an unwanted musical distortion when powering High-EFF, speakers that have large radiating surface areas, and have cables/wiring that is clean, efficient, and wideband.
The above are observed results and are not a set of personal opinions.
---Dennis---
Edits: 01/13/15 01/13/15
" The above are observed results and are not a set of personal opinions.
---Dennis---"
Since you observed these results instead of measuring them, they are all personal opinions. Further more, claiming that improved bass and more fleshed out sound is the result of a defect is incorrect. If an amp reproduces an acoustic bass in a natural manner, it can't be said to have exaggerated bass. If the mids and highs have a full sound that the original music has, it is correct.
Using examples like these as an excuse for an amp having a thin sound or lacking in bass is not being true to the source material. You may prefer that type of coloration but others may prefer a more natural sound.
Why bother to answer this. Anyone care to try his hand at it?
---Dennis---
" Current starvation can come from several sources:(1) Capacitors that store too much energy and release it too slowly. The cap's re-charge cycle takes current away from what is to be powered, and the release cycle of a large cap simply doesn't even get started (release isn't fast enough) until the musical transient has come and gone."
No. This is not correct. The larger the capacitor, the more steady the voltage across it will be under a given fluctuating load current. This is just a basic fact of how capacitors work.
Chris
Edits: 01/14/15
Sorry, but you are ignoring the re-charge cycle particularly. When a cap is recharging it is HOGGING CURRENT AWAY FROM the load.
When it is too large for the application, it's discharge/energy release cycle is VERY SLOW----wwwwwwwwwwwwww! YOU CAN HEAR THAT! It is NOT Thrilling!!!!!
This is so blatantly obvious to those builders that have experimented with capacitor and choke values in designing amps, that it's become ridiculous and repetitive to keep on repeating it.
Those old theories taught in those old tube books are not high fidelity-to-signal.
They NEVER WERE. I've used just about every tube amp out there for some sort of commercial app-- not all of them, but most of the best ones.
They DO NOT reproduce music RIGHT! NONE of those tube amps ever did...
Nothing built with those old, obsolete theories does today.
This is SO EASY to test! EASY! Get a Spectral DMA200S amp, or any 200 watt or greater Boulder, or a large, newest Bryston., etc., and see how it handles fast transient attacks in music.
Then, get out your tube amps-- I don't care-- get the best you know of, and watch them fall all over themselves trying to get out of the way of a GOOD amp.
Well, it just so happens that I designed a TUBE amp that actually works. For a while, it was the ONLY one. Now, it's starting to get some decent competition, and that is good-- VERY good. It means that I can give this up, retire, and have a good time.. That's right, we actually reproduce music, something tube amps normally fall down at.
Better look out! That old crap might include your amps if you followed all those old cap and choke theories for old push-pulls and tried to stuff them into a S.E. amp. Yes, it will sound slow-- just like all those other tube amps of yesteryear-- perhaps with today's VASTLY better resistors and caps, it will be a bit better, but will still fall short as far as reproducing today's best recorded music is concerned.
Someday, what's going on here will be common knowledge. Today, you can still get away with throwing darts at people like me who know what's up-- but all you're getting away with is Old Theory-- not anything scientific or provable by actual measured and listened-to musical performance.
Oh yes, it's s good idea to stop obsessing about what those old-fogies were measuring to sell cheaply designed amps with, and start measuring what actually matters-- musical reproduction SPEED, RESOLUTION, and DYNAMICS-- both Micro and Macro.
We're Light Years beyond that old stuff now. Your still popular Theory Train is slowing down and it's railroad tracks are starting to widen and loosen.. Reality could lie around the next Bend....
---Dennis---
You like the sound of a sloppy pose supply. There is mother wrong with that. At least you know what it is, so you can duplicate it in your production.
> Those old theories taught in those old tube books are not high
> fidelity-to-signal.
> They DO NOT reproduce music RIGHT! NONE of those tube amps ever did...
> Nothing built with those old, obsolete theories does today.
Oh, yes, all names and brands from Frank McIntosh to Bob Cordell, from Marantz to Sony must be wiped out from the history of audio in favor of Great Fraker Theory.
Peacockery and laughing-stock.
"We're Light Years beyond that old stuff now. Your still popular Theory Train is slowing down and it's railroad tracks are starting to widen and loosen.. Reality could lie around the next Bend...."
OK, so you like the sound that comes from a floppy power supply that wobbles with the load. Nothing wrong with that, if it's what you enjoy.
Chris
You are only talking about a SMALL portion of the power supply in my amps, and its an incomplete picture, not representative of whats really going on.
My power supply, unlike many / most others, is "all over the amp " and we have said this, going back many years now.
For example, I have a simple one-part shunt regulator, located ONLY 1/8 th of an inch from the point of use, the front end's plate resistor. It shunts over 15 times the audio current, than what the audio stage uses. Ninty percent of what we hear in a two stage 2A3 amp is the front end. WHAT do you think that Shunt Regulator does, to lock-in high performance??
And I am not even discussing the additional use of a Dennis Fraker " Final Filter", L/C, located 1/8th of an inch from the input stage's plate resistor. Who has those TWO items in their amp designs, no one except Dennis and I.....and anyone we have mentored.
So Chris, we can't intelligently discuss my preferred amp designs, unless we look at the whole circuit. My power supply, copying Dennis', is ALL OVER the AMP !! What you are doing is trying to play poker with one third of the deck !!
Enough of this .
Jeff Medwin
"So Chris, we can't intelligently discuss my preferred amp designs, unless we look at the whole circuit."
Maybe you could post a schematic, and then we can discuss it?
Chris
15 times .5ma is 7.5ma. So there is 8ma. total of which only .5ma. is moving.In the old days they call this form of voltage regulation a "clamped down" PS.
It does a good job preventing voltage fluctuations caused by the .5ma that is moving but it does nothing to prevent the voltage from changing because the source voltage is changing do to the large current swing of the output stage and a poorly regulated supply that's feeding the whole thing.
In this case the voltage regulator would need to regulate against both sides, the changing load and the changing source, to be of any real benefit.
I hope I wrote that clearly enough to be understood.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 01/13/15
Not even going to read it lol.Judging by the picture you posted you don't grasp the difference between energy storage device and something that dissipates energy.
Its very simple Drlomu it goes like this, I will even use your attachment for an example.
Power from the voltage source will prioritize the cap because it is the lowest impedance. 36 ohm vs 650 ohm
The tube conversely loads the capacitor because 36 ohm is lower vs whatever the resistance is of the choke etc.
It's a relay.That is why it is called a reservoir capacitor.
Similar to a water reservoir that is designed to collect and store sporadic additions of water, that can later be distributed in a even controlled fashion. Through valves even.-The reservoir needs to hold enough water to get you by between rainfalls.
-You need more rain then the water you consume per year.The bigger the reservoir is, the less it is going to drop in level per dry cycle. This is of particular interest to us because this water line is used as our voltage reference.
If this waterline stays fairly constant, then you can control valves in a predicable, dare I say linear fashion, because the water pressure is nearly always the same.
Edits: 01/12/15 01/12/15
Very simple. A friend's son was granted an interview with Microsoft for a summer internship when asked to explain the concept of "reduction" to a child. His example was Russian Nesting Dolls. Perfectly simple to understand.
my only long winded point being that what Jeff is describing can be made to work and don't dismiss it because of his troll like ways of spreading the information.
there is an EE or two out there that have spent time making it work that like variations on the "low everything supply." people with a lot more education and understanding on electronics than myself. jeff's gorilla marketing can be frustrating, but he means well.
Why is it so hard for people to say they like the way a sloppy supply sounds and measurements don't matter.
GG,
This is really sort of funny !! You have it very wrong. Please send me your private email address, and I will email you, as attachments, all the SWENSON and HASQUIN posts, in chronological order, for you to read and digest some.
If you don't want me to contact you directly, no problem, find a Forum Member we both know, and It could be forwarded, them first, to you second.
I understand your line of thought, its just that it is not correct. The first 50 mS. are "free" according to SWENSON's measurements of music.
Your call on proceeding, I have the posts in Word Files. I am just being fair and open with you, certainly you recognize that.
Jeff Medwin
Edits: 01/10/15
I can't see GEO's last two posts.
Hi again Jeff,
> > > the drop in the first 50 mS. is GOOD to be sharp and get "most" of the settling done smoothly and quickly as possible. < < <
I dunno, isn't the speed of the drop that only part of what matters? I would have thought the *magnitude* of the drop against time would also be an important aspect (wanting to keep the voltage up as transients hit), as would the time to recover and (lack of) overshoot and ringing.
Non-technical conceptualisation:
When a big transient hits, the PS voltage should fall fast enough to support sufficiently quick recovery, but should not fall far so as to maintain voltage for the transient. Recovery should be smooth and fast enough that voltage has recovered and the PS stabilised before the next big transient hits.
The caveat for me is, does the 15% stepped current in PSUD2 reflect anything like real-world conditions and can we really extrapolate audible effects from it?
Of course, this ignores PS impedance and maximum accepted ripple etc.
Regards,
91
"When a big transient hits, the PS voltage should fall fast enough to support sufficiently quick recovery, but should not fall far so as to maintain voltage for the transient. Recovery should be smooth and fast enough that voltage has recovered and the PS stabilised before the next big transient hits."In a class A circuit why would a big transient cause the current draw to increase longer than 1/4 of one wave length before the current draw starts down?
And 1/2 wave length later wouldn't the current draw be decreased from idle and the worry would be increased voltage?
1/4 wave length of the slowest frequency of interest (20Hz) is 12.5ms
If the supply is slow to react to current increases (and current decreases) and the voltage holds relatively steady for the first 12.5ms, until the current starts to decrease heading back to the idle current point, isn't that what we want?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 01/16/15
I think you have it nicely said on a conceptual basis. But I am not a EE Guru PSUD2 expert.
The 15% step was something EEs Swenson and Hasquin used. I just copied their examples Raymond.
Jeff
GG,
We "match" more now, wondered why we differed !! Now I know, GIGO.
You still have this LONG fully-settle time - 400 mS. It stays the same.
Now however, this cheap-wimpy-soggy 165 Ohm Power Transformer has increased the Z of your supply, to where its worse than ALT.1. Your B+ filter drops 8.83 VDC peak to trough settled, and ALT.1 drops about 7.83 VDC peak to trough. On a similar change of 12.25 mA. ( the current step ) your B+ Filter NOW has a calculated Z of 720 Ohms, and ALT.1 has a Z of 631 Ohms.
Amps with 165 Ohm Power Transformers and 270 Ohms chokes sound like you are listening to the music on your 604s, with a big woolen blanket thrown over the coaxial driver. What I may need to do is bring one of my DC amps up to Chicago area, next time I visit there, and let you hear it for yourself.
Jeff Medwin
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