I know this may not interest those of you not into DIY or how things work, but we have been playing with oil chokes, and let me tell you they may be the secret to the secret sauce!
I have been using a preamp that uses 4 oil chokes in the power supply, this preamp happens to be one of, no, the best preamp I ever heard. What made it special? The DHT tube, the exotic iron?, the oil chokes, the copper chassis'? Maybe a combo?
Well, my friend replaced his hammond choke in his Counterpoint Hybrid amp with a oil choke...
I was stunned, all trace of solid stateness is gone, replaced with simply gorgeous tone, air , openess , 3 dimensionality and weight throughtout the spectrum, not subtle at all. His hybrid sounds like a great tube amp with all the control of a SS. Something hybrids promised but never delivered.
The oil chokes are old and hard to find, and I am sure some guys with degrees in EE would poo poo them, but they probably never heard one. This is a whole new product, a renaissance of an old product. Oil caps have come back again in their modern iterations, we should be so lucky that oil chokes make a come back.
They are not subtle.
Don't look for these in any modern commercial product, there are just too few available for a manufacturer to even think about using them, but the DIY crowd have been playing with some secrets that eluded the masses. The mind wanders...imagine the possibilties ( I can)...very exciting stuff :thumb:
Just thought you might want to know.
mike
If supreme musicality and emotion is what you are searching for, these chokes may be able to help
Do you have any photos?.. I am intrigued, for sure.
I wonder what kind of oil is in there and if there are PCBs too.
And how much it would cost to clean your house if you sprung a pcb leak!
Couldn't be worse than breaking a 83 rectifier, filled with mercury gas! :duh
Quote from: Carlman on January 28, 2011, 12:24:54 PM
Do you have any photos?.. I am intrigued, for sure.
Well there are some here...
http://www.audionervosa.com/index.php?topic=2941.0
Yesterday I got a chance to hear several chokes both oil and conventional. There was a distinct difference to be heard. Dave Slagle build some different value non oil chokes on the spot and them compared to the 10 Henry Oil baby doll.
The addition of the oil choke swooned us. The Slagle attempts were not up to the oil choke until he hit the magic combo. Whatever that was. I believe 30 Henry but just not sure.
All I can say is I want them. The live experience was definitely enhanced with their use. Wether oil or conventional check these out. OMG.
If you cannot find or do not want oil chokes contact Dave Slagle. Totally and utterly convinced that these chokes will change your view on sound.
charles
agreed :thumb:
Here is a picture of the slagle nickel choke that was gorgeous sounding
I need a little resizing help...please
thanks
Here you go mike.
The one on the floor is that the Slagle dry choke?
Rich,
Yes that is the nickel choke, he actually made 3 of them in my kitchen, they all had a certain characteristic, subtle but there for anyone with ears.
These chokes should not make that much of a sonic difference....but they do :shock:
Just like caps, and resistors and power cords!
God it gets so confusing after a while :duh
Mike
another benefit is that dave can wind whatever size you need
Quote from: topround on March 27, 2011, 06:04:24 PM
I need a little resizing help...please
thanks
Mike,
This should help you out.
http://www.audionervosa.com/index.php?topic=2988.0
Where are you putting them, powersupply smoothing, or interstage signal?
Power supply.
charles
If you are going to play with chokes in the power supply, you may want to download PSUD-II power supply modeling software. It's free, here:
http://www.duncanamps.com/psud2/index.html
The problem with swapping different values of chokes in and out of a power supply is that you can unintentionally induce ringing or oscillation of the supply, and you will almost certainly change the voltage output unless the new choke has the same DC resistance (DCR) as the old. This software is very easy to use, with no programming ability needed, totally GUI - just a few clicks and you can swap in different RC, LC, C elements as well as different power transformers and rectifiers. One click simulates it all and you can then graphically display voltages and currents from any point in the circuit, and zoom in to see the magnitude of the ripple left after filtering. You can specify a resistive or constant current load and even step the load up and down to see how the supply reacts. You want fast, smooth recovery from transients without ringing.
I just used this to design a new power supply for my Supratek preamp and it sounds EXCELLENT. My power supply contains a tube shunt regulator, which PSUD does not have the ability to simulate, so I just did the part of the supply before the regulator and compared it to the stock setup. There were definitely certain combinations of chokes and caps that caused the supply to ring like a bell, but I wouldn't have known that with out doing the sim. I targeted the same voltage output as the stock configuration, 300V, and ended up with 299.1V - pretty accurate simulation! Ripple was 30uV (before the tube regulator!) By the way, I used Lundahl LL1638 dual coil C-core chokes - high inductance with very low DCR. There's a picture of the new supply in this thread:
http://www.audionervosa.com/index.php?topic=3062.0
Excellent!! Thanks a million Maxamillion!
Rich
'Tis amazing what chokes can do for a power supply. I modified a friends Cyber 845 amps as he found they had too much noise. Since they chose to use DC for the 845 filaments, I changed it from just a bridge with a 10mF cap to a CLC with 10mF/4H/10mF. The DCR on the choke was about .156R, so it dropped the voltage a bit but it was a little high to start with and ended up almost dead on the 10V the 845 is supposed to have.
While they measured quieter on the bench I didn't get a chance to listen to them before he picked them up so I was a little concerned. I received a call that went something like "what did you do, these are not the same amps". He was delighted, which of course was a huge relief.
I am on the lookout for some oil chokes to play with for my stuff but even 'dry' chokes can work wonders. :) I wholeheartedly agree with Maxamillion about using Duncan's PSU sim. :thumb:
Duncan Amps PSU sim charts. First is stock, second is CLC. Scale on left is volts.
Ok then Mgalusha, You got my Nervosa perking you devil. What about the Cyber 211 PS ? Same thing just a different voltage for the 211 tube ? just installed Jensen .47 PIO coulping cap of driver to 211 and so far a different amp. Liking anything oil these days.
charles
Impressive demonstration Mike. Adding one coil and another cap gives almost 10,000x reduction in heater noise. I often think of coils as expensive tweak, but that's getting into regulator territory. How big was the coil? The coils Max used in his preamp look pretty big. Do they have a magnetic core?
Those chokes have a C core of Lundahl's construction; they don't state what the details are. It's most likely silicon steel with maybe some nickel thrown in. They also have the same model with an amorphous iron core, but they cost $280 each and I'm not sure it's worth it in a power supply. I do use their amorphous cobalt core output transformers in my preamp, though - outstanding!
Their chokes use two coils on the single core, which allow them to be hooked up in several different ways, such as series for highest H, parallel for lower H but more current capability, and in a special common-mode noise reduction mode where one coil is in the + leg and the other is in the - leg. The latter is supposed to give some CM noise reduction while retaining the same high H value as the series hookup.
In my preamp I have the first choke in series and the second in CM hookup, in a CLCLC configuration.
And you could simulate all those variations on Duncan's app? Neat!
Lundahl importer and tube amp designer Kevin Carter lives in the next town over. Funny I haven't met him yet. Good stuff.
Well, using PSUD I only simulated with the series configuration, since both ways measure the same inductance. I had no intention of using the parallel hookup as I had plenty of current capability as is.
Quote from: rollo on April 19, 2011, 08:28:24 AM
Ok then Mgalusha, You got my Nervosa perking you devil. What about the Cyber 211 PS ? Same thing just a different voltage for the 211 tube ? just installed Jensen .47 PIO coulping cap of driver to 211 and so far a different amp. Liking anything oil these days.
Charles, I bought 4 of the chokes just haven't gotten time to work them into my 211's yet. :) The 211 uses the same filament supply at the 845.
I have the AmpOhm copper foil/paper in oil caps in the amps, I like the results. I also installed Cinemag input transformers so could have a real balanced input and kill the ground loop caused by 25ft interconnects.
Quote from: richidoo on April 19, 2011, 08:53:15 AM
Impressive demonstration Mike. Adding one coil and another cap gives almost 10,000x reduction in heater noise. I often think of coils as expensive tweak, but that's getting into regulator territory. How big was the coil? The coils Max used in his preamp look pretty big. Do they have a magnetic core?
Rich, in my case they were just regular old Hammond chokes. Unfortunately I just demonstrated that running a PSU simulation at work without the real data in front of me is dumb... I put 4H as the inductance but the 4 was the current rating of 4A. :duh The real value was 15mH. I reran the sim and it's attached. Not quite so good but still works out to about 20mV p-p, so still about 1000x better than before. I used the biggest iron I could physically get in the chassis. These were Hammond 159ZG, $26 each from radiosupply.com.
Mike
Very cool. Thanks Mike.
For heater impedance is no biggie, but for B+ how do the more complex passive filter schemes (with coils) affect source impedance?
What are the sonic differences of a coil filtered B+ vs. a super regulator like Hynes or Belleson. I know the technical differences, but wondering if anyone has compared the two for sound quality / emotional effect in a preamp or source.
Thanks
That's one reason I used the LL1638's. 10H inductance, up to 215mA DC current, and only 36ohm DCR. My stock 10H coil was 165ohm DCR. I was able to shoehorn in 2 Lundahls, double the inductance, improve the filtration by a factor of more than 100, and reduce the DCR by 93 ohms.
If my preamp didn't have a phono stage (and thus higher DC current), I could have gone for the LL1673, which can give you 20H in a single unit with 60 ohms DCR, but saturates at 140mA.
Quote from: mgalusha on April 19, 2011, 02:24:46 PM
Quote from: rollo on April 19, 2011, 08:28:24 AM
OK then Mgalusha, You got my Nervosa perking you devil. What about the Cyber 211 PS ? Same thing just a different voltage for the 211 tube ? just installed Jensen .47 PIO coupling cap of driver to 211 and so far a different amp. Liking anything oil these days.
Charles, I bought 4 of the chokes just haven't gotten time to work them into my 211's yet. :) The 211 uses the same filament supply at the 845.
I have the AmpOhm copper foil/paper in oil caps in the amps, I like the results. I also installed Cinemag input transformers so could have a real balanced input and kill the ground loop caused by 25ft interconnects.
Thanks for the response so then [ just to make sure] what value choke should I buy for the 211 ? Just installed Jensen PIO, copper at the 5687 coupling position and had a V-cap Teflon at the input, liking it so far, trying a new Deuland ' "Alexander" PIO next.
BTW what 211 tube are you using ? Using GE 4TC with Tungsol 5687 driver and Matushita 6DJ8 as input. Have you tried the Pavane 211 ?
charles