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01-07-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 81
Post ID: 6303
Reply to: 6292
Playing with new power supply.

I was playing with new power supply over this weekend, trying to optimize everything. First I got rid of bleeders at all B+ - it has enough critical current with them according to my measurements after the bride. All supplies after the first choke have no ripples but a perfect sinusoid. The AC after the second filtering stage in the all supplied except the single-stages is un-measurable. The single-stages B+ has after LCRC (200uf, 15H, 500R, 100uF) AC of 5mV. I will see if it is stay when I will be listening the thing – I might drive the capacitance lover.

Those Silicon Carbide diodes are very nice and I have an accidental stress testing. I made all PS to be shorted by 50R resistor as the amp turned off. I use 3 individual 5A relays that turned to be too flimsy for the task as the capacitance of the two stages supple is too large. So, one of the relays but welded and when I turned the amps next time the B+ of the first stage was shorted by 50R resistor. It is 75W aluminum resistor direct-mounted on the metal chassis (not visible on the picture above).  So, I turned the amps and went to shower. When I got back my room was full of smoke, I ran to the amp to shut it down, figuring that it should be all burned. The entire amp’s chassis was near 80-90C, I turned the amps off. The 50R resistor was the temperature of supernova. It was not burned through though and the diodes DID NOT BURN!!!!  The resistor after baking measured 33R. Well, I figured that 33R against 400V – so we are taking about the 12A of continue currant – not bad at all for 600V Schottky!!!

There is some open issuers as well. If to look between the bridge and the first choke the beginning of the waves look very strange. If you look at the picture then you will see that voltage go to zero as it shell (calibrated at first square), then there is a there is very small horizontal step and then, what the new wave states there is a very strange vertical half square rise. I wonder where it comes from. Is it some kind of anomalies of my toroidal chokes? Should I worry about it? The voltage after the choke gets converted into as perfect sinusoid anyhow… I do not know the answer yet.

RingingAfterBridge.jpg

Also, the 400V supply, driven into the toroidal choke show some choke ringing. I wonder if I need to fight with it. The choke overrides the ripples into sinewave anyhow and the second filtration stage kills any sights of AC anyhow. So, how bad the choke ringing and does it has any effect to sound? One of the advantages of use the very large last cap is that all “qualities” of PS become less relevant from sonic point of view. So, does the choke ringing matters?

Rgs, The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-07-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 82
Post ID: 6305
Reply to: 6303
Diode Handoff
Looks to me like the horizontal and vertical steps in the waveform are due to the diode switching.  One diode turns off while the other turns on.  Storage time on the diodes is normally short.  But it depends on the test setup!  They are tested from positive current to negative current - how long do they take to turn off?  Probably 50ns or 100ns.

However, we do not have that test circuit here.  We do not turn off or reverse the current.  The load is a large choke, acting like a flywheel in that it is continuously pulling current, regardless of voltages on the diode.  So even with input sinusoid going negative, the diode still conducts forward.  During zero crossover, one diode should hand off current to the other.  Well, the conducting diode has to turn off first.  It does not turn off properly as there is nothing to sweep the majority carriers out of the junction (it is NOT reverse biased!).  And so it turns off slowly.  Meanwhile, you get an autoformer effect between secondaries, thereby screwing up the sinusoid.  Look at the voltage on the other side of the diode, it will have a discontinuity at zero volts.  Add in the leakage inductances from the secondary, and you get this unusual glitch.  The vertical step is when the diode finally turns off and the other one begins to conduct.  I think if the leakage of the secondary were lower, the diodes switch faster.

This won't happen with vacuum rectifiers.  Only with solid state diodes.  The question is, how to turn off a diode while still forward conducting? 

Meanwhile, the LC will filter this glitch out and it won't be a problem on the audio side.  It will, however, get reflected back onto your ac mains, where it can find its way into something else.  A snubber on the transformer might help.

jh
01-08-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 83
Post ID: 6309
Reply to: 6305
The high voltage input chokes and the snubbers.
Yes, Jim, thanks. It is what I thought. I have some “pure” ringing at 440V line as well. After consulting with 5 creditable people I desided to discard the problem. Since the choke on it’s another side gives a perfect sinusoid with no spikes or distortions of any kind I would close my eyes on the input ringing. I will test how mach the “ringing” goes back to transformer primary and for now I would not worry about it. When I will have the amp “soundable” I will test the 440V line listening is the elimination of the “ringing” affect sound ( I will try to use CR resonator at choke’s input or to use another parallel chokes). If killing the ringing will not affect sound I will keep everything as is now. Interesting that I was trying toroidal and regular chokes and have the same ringing result – the high voltage is apparently is the key. BTW, did you detect of a RC snubbers affect sound? I really do not want a bridge to see anything besides an inductor…

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-08-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 84
Post ID: 6310
Reply to: 6309
The Usual Snub
Snubbers are more effective when there is no inductor - just a diode/capacitor rectification.  That's when they become useful.  To snub out the ringing caused by leakage inductance.  Keeps the "buzz" from coupling to other areas of the circuit.

With the inductive input, a snubber in the wrong place will add current spikes through ground where you may not want them.  I'll put a snubber across the secondary sometimes.  But like you say, it's not good to mess with the induction.  We want that smoothing effect. 

I have the same glitch on several of my supplies.  My answer so far is to put a small RC on the primary side.  It is to keep the higher bandwidth components of the glitch from heading back out the line.  Works both ways, as I get an RC filter on any RF hash on the ac line coming in.  With higher powered gear, the R ends up too small.  But in something like my headphone amp, I get 44 ohms and 0.01uF.  It does three things, 1) drop line voltage from 120V to 115V (transformer runs much better), 2) gives me a low pass filter of 360kHz, 3) reduces the glitch energy pushed back onto the ac line.



jh
01-09-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 85
Post ID: 6312
Reply to: 6289
The second 6-Channel Milq diaries #12: the first nigh
Today the second 6-way Super Milq is done in bench version and looks like fully functional. I actually did listen all channels with a full range speaker – they sound fine. All operational parameters are there and look like I will leave the amp to run over night for now. I think in a week or two it will be ready to close it up. I can not wait when I will be though with it – too much work…




"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-09-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 86
Post ID: 6313
Reply to: 6312
Not power hungry 6-channel.
I made some power measurement of the Super Milq, to my surprise it is not so much hungry east as I expected. During the startup, what the B+ begins to charge the large capacitors the amp sucks 8,6A. When the amps is fully charge, heated and in it cruse mode it sucks 2.86A. My power meter shows 330W, instead of 243W, the power factor is 0.95. So, the 330W is not so bad (two 6C33C are running with one anode). I have 8A slow blow fuse on anode voltages and 1.5A fast-blow for filaments. The only one subject that I am still contemplating is if to use my 1A IE transformer for 6C33C plate of to go for my 3A toroidal. Anyhow, what I learned playing with it so far that in use to go for a dedicated fully independent power supply for the single-stage amps was very right direction to go. I ma sure I will talk up about it more.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-11-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 87
Post ID: 6333
Reply to: 6313
Turning off diodes
I stumbled upon this.  And noticed the extra 6.8mH balun ahead of the diodes.  Hmmm, I wonder if this can help snap that diode off?  Seems very counterintuitive.  Or maybe it is wired up not as a common mode choke?  Need to think about this, can't quite grasp the operation yet. 



jh
01-12-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 88
Post ID: 6334
Reply to: 6312
The second 6-Ch Super Milq diaries: Channels response.
Ok, here is the final frequency response for each Super Milq channel. The souse was Denon CD player that rolls off a little atop. I did not measure the tweeter as I have no tweeters transformer plugged in yet. All secondary in amp are grounded. The measurements were at each channel secondary loaded to 8R full-range 5” speaker. Again – it is not a 8R resistor but a “full-range “driver as you can see that amp reacts to it. It is fine with me I know this driver verb well. It looks like the all crossover hit home run and the amp it ready to go. The nose in each channel (besides MF) is less then 0.001V, with no measurable ripples above the nose floor. The nose stricture measured with my high sensitively HP1200A appears completely random with no patters of any kind. The MF has identical noise but 0.004V AC, no ripples but a pure sinusoid. I will be closing this amp this weekend…

Below, Denon response direct to TRA

Below, Bass Channel

Below, Bass Channel 12dB/octave

Below, UpperBass Channel 6dB

Below, Fundamentals Channel

Below, MF Channel

Below, Injection Channel




"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-12-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 89
Post ID: 6338
Reply to: 6187
The mystery of Ansar capacitors in Melquiades.
 Romy the Cat wrote:

I really do not know what is going on and how to explain the phenomena; I just dump it to you “as is”.  Because of multiple reasons I decided to drain the Milq’s power supply when the amp shits down. I have a set of four 6A double-poll relays that short the first cap of each power supply to a powerful 50R resistor. (For the people who what to thing here is a homework: why the sorting resistor must NOT be between the input chokes and rectifier but only beforethe chokes?)

So, when the amp is off then all caps begin to discharge backward, via the relays, to the 50R resistor. I presume that the higher capacitance of caps and higher voltage the more current flows back during discharge. I took very high quality 6A Japanese relay, bridged the 6A poles (12A), and figure out that it will be enough. It was perfectly enough, worked fine with the 6-ch Milq, that is in operation for a few months, but recently I got problems. With introduction to the recent revision the 200V power supply with non-electrolytic capacitors the new power supply begin to burn my relays. Thai is kind of funny. The 440V/8.000uF does not do it. The 220V/30.000uF does not hurt the relays as well. However, the 300uF of non-electrolytic capacitors (metalized polypropylene) weld the contacts off my relay. It is not happening immediately but this happen already 3 times and it forced me to order industrial 24A+24A relay to use with my polypropylene power supply.

So, I wonder what is going on. Do the non-electrolytic caps have MUCH faster discharge rate that make them to develop higher currant during the discharge? Very interesting…

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-13-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 90
Post ID: 6340
Reply to: 6338
Too much current
Maybe if you didn't try to pull the caps down so fast.  Why the hurry?  Maybe a 500 ohm or 5k ohm resistor would be a more kind bleeder.  I think the peak current spike is not such a good thing for the capacitor.  You are also at the limit of the relay contacts.  There might be something in the relay specs that set a maximum for switching energy (V*I*t).  Six amps at 12 volts is easier on the contacts then 3 amps at 200 volts.  Perhaps there is an SOA curve, like for transistors?  I have not looked.

Also, at super high currents, the capacitors may not stay linear.  Sure they have ESR.  Maybe ESL limits the current in the electrolytics?  Maybe there is more to electrolytic chemical reactions we are not familiar with.  Basically, I think their risetime (to a current step) is slower than the film caps.  Maybe related to DA (dielectric absorption).  Multiple time contants in these devices.

How about using a MOSFET instead of a relay?

jh
01-14-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 91
Post ID: 6354
Reply to: 6187
The new power supply for MF channel: the Sound

Those who flow what is going on with my 6-Ch Milq know that for sniggle driver stage I this revision I went what for non-electrolytic capacitors. I use a mandatory for me input choke with 200uF on PS side and then 100R and 100uF on the amps side to ground. The caps I use British Ansar, metalized polypropylene 450V.

I have been listing this new MF channel for a few days. My typical way to access a MF channel is a long tradition for me: disconnect everything besides MF and Upperbass channels and listen string quartets. There are a lot of middle and late Beethoven’s quartets, Dvorak's, Bartok’s and Schubert's quartets is being played lately in my room.

What can I say about sound of the new MF channel? I hate it, I really do. At this point I do not know why it is. Perhaps the caps are garbage, perhaps the diodes are not good, perhaps the caps need time to break in, the OPT problems or perhaps I am experience of hundreds other problems that screw up Sound. I know that something is wrong. The MF channel sound now with the new amp very flat and not articulate, it has some very odd compression. It probably the worst sound I ever got out of S2 driver. Other might feel that it has the “field-coil softness” – not me. I call that softness as transience deficiency and the driver disability to go into the dancers regions.  It sounds almost like Altec 808 with symbiotic diaphragm driver by 2W amp - what would be more disgusting? It is also important that the “tone” of the driver also collapsed (I would like do not let me to get stated about the tone of my MF driver  now – it sounds like somebody is tapping atop of a turned upside down cooking pot!!!). I have also not idea why it is so and I have also not idea what is going on. I will keep to burn the Ansar caps for a next week or so then try to go back with my electrolytic to see if it will do a difference and return Sound where I must be.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-14-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,104
Joined on 10-12-2006

Post #: 92
Post ID: 6355
Reply to: 6354
Back tracking
Romy, isn't this the first time you have tried the film caps for PS and the "ALL-NEW" "SUPER-SOFT" diode bridge?  I would certainly go back to known quantities before I did or un-did anything serious.  Not that I always follow the "1 Change At A Time" rule; I just usually wind up having to do it that way eventually...

Meanwhile, I suppose you'd know for sure if the biggest problem was the effing electricity?

Not trying to piss you off, honestly; my own bad electricity shows up with some new symptoms about every month.  I really should keep an electricity log.

Best regards,
Paul S
01-14-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 93
Post ID: 6356
Reply to: 6355
This time it has nothing to do with electricity

 Paul S wrote:
Romy, isn't this the first time you have tried the film caps for PS and the "ALL-NEW" "SUPER-SOFT" diode bridge?  I would certainly go back to known quantities before I did or un-did anything serious.  Not that I always follow the "1 Change At A Time" rule; I just usually wind up having to do it that way eventually...

Meanwhile, I suppose you'd know for sure if the biggest problem was the effing electricity?

Not trying to piss you off, honestly; my own bad electricity shows up with some new symptoms about every month.  I really should keep an electricity log.

It is not electricity for sure as I have left channel 6-way amp that I was running in identical configuration. The right and left MF (the same signal) sound not as two different amps but as two amps coming from two different planets. I need to investigate it further as something is obviously very wrong.

Well, it “might” be related to electricity as the left amp has single driver getting power from 15.000 cap. With 30mA load that channel works from a virtual DC buttery with this amount of capacitance and the cap never discharged. So, the PS with enormous capacitance usually more immuned to electricity problem that the PS what the power caps are constancy fully recharged. That was that a whole idea to use outsized caps in Milq in order to eliminate the contribution to sound of rectifiers, cables, chokes caps, transformer and the rest crap. Milq is less sensitive to electricity then my front gear, not immuned though…

I will look for the answers replacing the elements in the following order:

1)    S2 Driver
2)    Both filtering Caps
3)    Choke
4)    Rectifiers
5)    Transformer

It is kind of suck as with learning why I lost MF on the right channel I can not to move forward to finish the 6-Ch Milq project.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-15-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 94
Post ID: 6357
Reply to: 6356
Snyeg
biggest problem was the effing electricity?


I was thinking the same.  Maybe due to the snowfall?  Or the reaction of all the other folks in your neighborhood to the snowfall?  Behaviour patterns and power usage are out of the ordinary.  Check the mains voltage? 

jh
01-15-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 95
Post ID: 6358
Reply to: 6357
I still do not think that it is electricity…

…as the similar channel on the left amps play perfectly fine and very differently. I did switch the S2 drivers and it had no result. The most funny is that the right channel has very plastic horn honk – where the hell THAT come from? I cannot stress how heavy that horn is 0 it is actually funny how it sounds. Any plucking of strings sounds like a toping of an empty shoebox. Tonally the channel plays virtually juts one note with a very minor deviation of volume or frequency. I begin even to think that I might check out the OPT as well. Who knows… 

I actually if I have time tonight will run a wire from well-sounding 200V from the left amp to the new right amp. It would be fun it after all I will learn that my high voltage silicon carbide diodes or the Ansar caps have that “Sound”. Anyhow, I would not put blame at this point to anything and I clearly do not know where this sonic misery came from…

Meanwhile the amp is running for 5 days already non-stopping that made the caps to have over 125 hours on them…  Let see what the new day will bring. It would be fun if another Audiophile myths turn out to be … bogus.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-15-2008 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 441
Joined on 01-07-2006

Post #: 96
Post ID: 6359
Reply to: 6358
HF ringing?
Romy, cats, dogs, i drugie zveri

one of my first posts here...May I suggest one mechanism, speaking out of pure theory here:
the ansars have alledgedly much smaller esl+esr than mastodont electrolytics.
This creates higher Q tanks, also higher tuned. The switching
of your diodes seems to be rather...hmm not perfect, which can exite
the parasitic tanks or the possible combinations of parasitic and
actual elements. The ringing, e.g. via various IM mechanism might go as low as  MF.
Just some speculations...


Rgds,
N-set


Cheers,
Jarek
01-16-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 97
Post ID: 6361
Reply to: 6359
More "literature" about my faulty power supply

Well, the subject of capacitors in that PS should be resolved. We discussed it a lot with Dima and he feel that I am fool all my idea to try in this supply “minimum capacitance”. He actually does not believe in small capacitance, he has a vision how the last capacitor participate in signal path and according to him the last cap should be large. Dima feels that zillions of SET out there with 20uf or 60uF capacitance the plate sound as horrible as they sound because the imposer recharging pattern of the last cap (one of the reason) and therefore the PS are improperly decupled from tube plate. I do not know if it is correct and if it is play in my case. I never experience any problem with PS sound but I always used very large last cap. According to Dima a sufficiently-large last capacitor with using in input choke make the sound or transformer, rectifier and choke less relevant. It is possible that he is right as it was my very first PS where the last cap was less than 2000uF -3000uF. Perhaps now, with “minimum capacitance” the maternal of the caps begin to “sound”.

N-set, you said that switching of my diodes has a lot of room to be better; could you elaborate could/should I manage it?  Thanks.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-16-2008 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 441
Joined on 01-07-2006

Post #: 98
Post ID: 6362
Reply to: 6361
Switching
>N-set, you said that switching of my diodes has a lot of room to be better; could you elaborate could/should I manage it?  Thanks.

Romy, I have only a very limited experience with vacuum diodes, not with sand. The kink is a bit worrying.
I believe Hagtech's explanation of it is correct (the charge storage in the junction is a pita!).
I don't remember seeing such kinks in my tube PS (no comments on the sound though, those were only models!).
How much you can improve with sand diodes I don't know.

Sorry for a typical DIY BS, but L. Olson claimes
to have tested the switching of soft rec sand and various tubes, singleing out TV dampers as the best.
He has never posted any oscillogrammes nor the soft recs he has tested, so take it as you wish.
It *might* be that SS matches well with big elcos, while tubes with smaller mkp/paper???

Cheers,
jk




Cheers,
Jarek
01-16-2008 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 99
Post ID: 6363
Reply to: 6362
Big Caps
a sufficiently-large last capacitor with using in input choke make the sound or transformer, rectifier and choke less relevant


I have to agree with Dima.  The power supply has to be harmonious with the amplifier yet separate at the same time.  With one amplifier, I cheated and put 1/2 the capacitance needed (per my calculations) for a final cap, and under light loading the amplifier actually ended up with a 2dB boost at 20Hz.  The power supply LC was reacting with the amplifier. 

Seems to me a small film cap added to a large electrolytic solves most of the sonic issues people complain about re the large caps.

jh
01-16-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,486
Joined on 05-28-2004

Post #: 100
Post ID: 6364
Reply to: 6363
Yes, perhaps the size does mater….

… but there is no one to ask how mater it is…

 hagtech wrote:
Seems to me a small film cap added to a large electrolytic solves most of the sonic issues people complain about re the large caps.

Hm, I do not know. I think if good caps used then the bypass might not be necessary. I am big fun of Nichikon capacitors, to me they are absolutely as good as capacitors should be. The Super Milq’s B+ for 6C33C uses 350V/15.000uF for each tube. A year or so ago I did bypass those big caps with 2uF polypropylene caps. I use the 590Cudes, the caps I know very well and that I trust to serve coupling duty. So, I bypassed the big Nichikon with Cubs…the 2uF was the right value… and I can NOT report that I heard any improvement or any serious difference. I decided to keep the Cubes in there but… only because I have spent efforts to put them in – there is no other auditable reasons.

As I said I can’t not judge if the excessive amount of last cap eliminates the sonic contributions of the elements before the caps. However this vision dose sounds reasonable to me. Evan if I change my 100uF Ansar to 3.000 Nichicon and get right Sound then would it be the amount of capacitate or the time of capacitate? I think I need to change the Ansar to 100uF Nichicon… no matter how much I hate those experiments….

I still wish that the problem would be with caps and it would be easier to replace or to add…

Rgs, The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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