oil chokes

topround · January 26, 2011, 07:16:08 PM

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

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

Carlman · January 28, 2011, 12:24:54 PM

Do you have any photos?.. I am intrigued, for sure.

mfsoa · January 28, 2011, 02:40:26 PM

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!

topround · January 28, 2011, 03:07:25 PM

Couldn't be worse than breaking a 83 rectifier, filled with mercury gas!

Barry (NJ) · February 27, 2011, 08:06:14 PM

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

rollo · March 27, 2011, 03:29:38 PM

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

topround · March 27, 2011, 06:03:05 PM

agreed

Here is a picture of the slagle nickel choke that was gorgeous sounding

topround · March 27, 2011, 06:04:24 PM

I need a little resizing help...please
thanks

richidoo · March 27, 2011, 06:12:09 PM

Here you go mike.

The one on the floor is that the Slagle dry choke?

topround · March 27, 2011, 07:13:27 PM

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

Just like caps, and resistors and power cords!
God it gets so confusing after a while

Mike

topround · March 27, 2011, 07:48:49 PM

another benefit is that dave can wind whatever size you need

tmazz · March 28, 2011, 05:15:14 AM

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

richidoo · March 28, 2011, 06:35:58 AM

Where are you putting them, powersupply smoothing, or interstage signal?

rollo · March 29, 2011, 10:05:04 AM

Power supply.

charles

Maxamillion · April 19, 2011, 06:08:21 AM

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