Modding the DirectStream DAC

I will be 3D printing a mounting part that has the same pins and footprint as the original transformer. The Jenson will then fit in this part and mount like the original Transformer did.

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These transformers retail for $299 each however you can find them used for around $60.00 each.

Here’s the DS schematic with two possible Edcor transformer footprints in parallel. The XS4400 is pin compatible with the original DS (labeled PCW150/150) since I wired the two inputs in parallel and the two outputs in parallel on the board to match the other Edcor transformers which do that internally.

You can’t wire the Jensen exactly the same as the Edcor since the Jensen doesn’t have center taps.

Weirdly, wire the Jensen inputs in series and its outputs in series to match the DS’s use of the Edcor transformers which has its inputs in parallel and outputs in parallel.

Red - Pin 1 or 4
Brown and Yellow tied together, but not connected to any old pins.
Orange - Pin 3 or 6

Gry - Pin 7 or 10
Violate and Blue tied together and connected to pin 8 or pin 11
Green - Pin 9 or 12

If you want more gain, wire as follows on the input side:
Red and Yellow tied together and connected to one of pin 1 or pin 4
Brown and Orange tied together and connected to one of pin 3 or pin 6

The output side of the transformer is wired the same for either gain.

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My comment here would be, since the trafo in question is not ct output it likely wont be a true comparison. Just thinking out loud, there will possibly be some signal reference shifting around involved that might be similar to effects of Vocm. Thoughts?

No, the transformer is quadfiler so using two windings in series with their common as the “center tap” is fine. The two outputs are probably better matched than the arms of most center tapped windings.

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For example Jensen’s Ap note 93:

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Ahh, gotcha, thanks.

Todd

Thanks so much Ted. That’s exactly what I needed. I’ll report back when it’s finished.

Hi wiesiek, any updates on your Lundahl LL1684 trafo testing? Lundhal trafos seems a lot more available than the Jensen high end trafos…

Ted. If I pull the existing transformers and install jumpers to bypass the transformer so I can test different transformers using the XLR balanced outs? In other words is there any circuitry between the transformers and the XLR outs? I have a couple transformers I would like to test and it would be faster to just wire up the transformers to XLR male / female (so the signal passes through the transformers before it hits my preamp).

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If you don’t care about using the 20dB attenuator you can ignore (or bypass) the four 120 Ohm resistors and then the XLR outputs are the same as the transformer outputs.

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Thanks Ted!
I have been listening to a completely stock DSD for the last week so I can be prepared to hear the real difference between these transformers on a stock DSD. It will be much faster comparing by just swapping the transformers externally by just unplugging and plugging transformers / XLR cables.

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FrankenDSD!
image

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I’d wonder about that extra lead length in the transformer listening. It might affect things. :thinking:

Twisting the leads provides a lot of common mode rejection: I used a wired Jensen on my original prototypes and they sounded great:

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Virgin board… ready to break ground on DAC#2. I expect this to be even better still as it will have no trafos. Interesting how the units differ (I’ve seen inside 3 now). This last one has a full length wall/“shield” between the PSU board and the analog/digital board. My friend’s had like a half shield. Mine had no shield.

Meanwhile my friend with the new Sonus Fabre still has DAC#1. He’s still raving about it and says I can’t have it back lol :wink: He also remarked today that he feels no need to hear his vinyl rig either now (that’s a first). That’s high praise indeed. And there’s already a waiting list forming. He took it to some other guys houses and it easily won vs whatever they have. These are not Best Buy customers, these are hard core audiophiles who attend shows, etc and with lots of gear and decades of experience.

Speaking of shows, we have a local one (Austin) headlined by Schiit and Emotiva among others in July. I’m going, of course. I had a Schiit Yggy DAC for a (short) while not long ago.

He also said the Audioquest exec was impressed with DAC#1. BTW he lives in Houston, not Dallas. And he also has a dCS DAC… hmmmm, I love a good challenge :wink:

Meanwhile a Terminator Plus plays nicely while I work here. I had placed analog bypass across all (56) switches that drive the ladders. It sounds d-rn good in its own right too, I must say. Spoiled :wink: Stay tuned please :slight_smile: T

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That is so very clever. Right on! Have fun!

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I am tuned in to Channel T(urbotk)!!!

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Hi,
everything will be postponed by a week. I am in hospital from Tuesday to next Monday.
I’m not exaggerating, I’m in good health, all the tests are normal, but on Tuesday I felt a pain in my chest and it turned out that my arteries were blocked. Doctors put stents in two arteries and everything is back to normal, it will be even better than before. In Poland, treatment is free (maybe apart from the dentist), and in a life-threatening situation, help is immediate.
I greet all my colleagues.

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Great to hear all is well, rest and recuperate and best wishes.