Modding the DirectStream DAC

Go ahead JK, add some flames to the sides :slight_smile: T

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As long as I don’t let the smoke out we’re good😜

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Lundahl Factory back from vacation next week! Can’t wait to get the new transformers and installation kit.

-Alan

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It’d be great if someone could do a comparison of the Edcors and now these Lundahls in the DS. Just sayin’. :slightly_smiling_face:

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Yes good news, and I’ve been able to listen to DAC1 with the LL1948 again vs DAC2 with no trafos. DAC1 still sounds very good, the LL1948 are quite good. In fact good enough that I’m forced now to try and drill down a little deeper the next few days to be fair and compare them more apples to apples (same wire, etc) and see where they stand. Get a true handle on how they compare vs no trafo.

I spent several hours last night re-wiring DAC2 with the winning wire. It’s truly amazing to me what a difference even a few inches of wire can make. Of course in DAC2 we’re pretty much only listening to the sound of a couple of passives basically, including the wire. About as pure as it will get. And yes, all those passives have big, big differences at this level. So it has to be optimized to get the best result.

Post a clip below of it playing a Mister Magic live (Bob James) with some interesting (and clear as h-ck) drum stick and drum solo about midway through. If/when Google will allow it that is :roll_eyes: The DAC2 boards are in the silver DAC1 chassis here. This is with 1 pr of Front Row ic in the system so far; others are cooking and getting ready to ship soon. T

Hi T, may I ask what cables you are using to hook up the Lundahl LL1948 line output trafo?

Is it better than the:

Thanks

Hi T, thanks for your PM on this topic. I might try another round of mods using this Audio Note cable. I also asked Hifi Collective for their advise, see what comes out.

I have received the adapter kit boards. As soon as the transformers arrive I can do a final fit and test and ship the kits and kits/transformers out. The adapter boards look and electrically test good.

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Edcors are not even close to the Jensen’s as far as open top end and tight clear bass. I would imagine the 1948’s will be very close maybe better? Everyone who ordered them will know in a few weeks.

For anyone that hasn’t purchased the LL1948’s…I was half expecting a wait time for them. Yesterday, I emailed my request to Erhard Audio. In stock and I had a purchase order/USPS tracking number within an hour of payment.

Not sure when I’ll have time to install them along w/the adapter boards but am looking forward to it. I have a pair of 4400’s that haven’t been installed, so if anyone’s interested I’d be willing to send at cost and I’ll cover shipping. Please PM and we can work out details.

Thanks, Jeff, for moving this along so fast. Nice to have such competent and trusted folks on this forum. Same goes for the Ted, T and other’s that have contributed to all the experimentation and mods.

Yes, Erhard-audio is the US distributor for Lundahl. Glad you found them in the states.

Google finally released the video clip lol. I hope the AI bots enjoyed.
This is what I mean by “Low Noise Floor Clarity” (LNFC) :slight_smile:

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Well I think the DAC2 is about ready to go out here. In silver chassis- yes, they’re swapped because the silver had a proto shield already built. I put it back together this afternoon for good I think. Just lacks the lid.

-I need to find a good shipping box for it this week. And do some comparing with the updates in progress on DAC1. Then its ready to go.

DAC1 will soon go to the DFW area for similar. A request for it was also add a 2nd pair of XLR outs to allow bi-amping directly. It will be a bit challenging to fit but we’ll fire up the garage machine shop (lol) and do it.

-This is the full current DAC2 no trafos spec. OA converted to DSD bit buffers, which feed precision passive low pass filters for D/A conversion which drive the output directly. No transformers. It uses the best parts I know of basically. It sounds amazing.

-PLEASE pm me with your name and complete shipping address and phone and emall (for Fedex). I’ll keep the personal information confidential of course, other than first name or handle used here.

-PLEASE also indicate if you use RCA or XLR outputs. I’m thinking about maybe also including a pair of Front Row interconnect for trial use. Maybe. Please let me know your thought on this in the pm.

I’m also thinking about 1 week or so should be good to check it out. That’s not set in stone and we can discuss. I don’t expect it but reality is some may not like it and be done in 1 day. Otherwise, the list may grow dynamically. We’ll see. But please be ready and available and system ready to try out the DAC; otherwise please postpone your trial until ready. Lets try and keep it moving along crisply.

-PLEASE- Terms: -Handle with care- it is a hand made prototype. And it was not cheap. We’d also like to preserve the cosmetics as much as possible please. -Do not open the DAC. If you have questions, just ask. -Please share what you heard and think. -When finished with it please prepare it (and the cables possibly) very carefully to ship to the next destination. -Then please ship it promptly, with tracking updates provided for the next destination and myself. -If not using Fedex please insure for $3000 or declare the value $3000 (Fedex). I am willing to create the Fedex labels for this.

-I will have a Fedex bag on the box for the shipping label. The plan is that this bag will serve for all labels; please handle it with care. I can create the Fedex shipping label and email it if need be. Then just print it, fold in half and insert in the bag. Please then PP me the 1 way shipping cost for reimbursement (from you to next destination). I’ll cover the initial send out. I would prefer to not use the USPS please- either Fedex or UPS only.

Update- Think I’m going to buy a hard case (they’re not cheap!) with some combination locks for the DAC travels. And think I’ll do all the Fedex shipping labels from here. And cables, think they should go separate in a Fedex small box to where they’re needed, as not everyone will.
I have ordered 1 pr of 1.5m RCA Front Row and 1 pr 1.5m XLR Front Row for demo.

Thanks! T

Hard case and locks:

Front Row :+1:

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@tedsmith
I was wondering if we disconnected the 2nd set of center tapped secondary windings from the 4400 transformer wouldn’t that gain 6dB output versus paralleling them. The primary would still be paralleled as they are.

In the stock DS (and with a DS with the XS4400 swapped in) both the primaries and the secondaries of the transformer are in parallel. Disconnecting one half of either the primaries or the secondaries won’t change the voltages. It will change the output impedance of the DAC, but since the output impedance is on the order of 100 ohms and the input to your amp or preamp is closer to 100,000 Ohms any difference caused by output impedance in a typical system is quite small.

When you change the connections on the audio transformer by converting the parallel connection on the input or the output to series you either half or double the output voltage (or leave it alone if you change both the input and output impedance.

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What configuration are we listening to now?

The full DAC2 config is playing here now. Later this evening I’ll have the final DAC2 vs DAC1 showdown and see where the trafo output stands. T

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