Modding the DirectStream DAC

What should we expect during the break-in period for the ll1948 and ll1948Ag amorphous core transformers?

The XS440’s cycled from louder and quieter so it was obvious when the break-in period was over.

-Alan

I have three volume controls with the following settings:

DS Sr. DAC = 100% → mconnect player = 100% → preamp 25% to 40% → listening level max at 70db.

I listen to a variety of music, Blues, Jazz and Classical.

Should I set the DAC to 94% and increase the preamp percentage up a few steps or leave it as is to use the cleaner algorithm? It sounds like I should be ok leaving it as is.

Thanks,

-Alan

It’s simply personal preference. If you’ve never tried 94 it might be worth trying, but no one can predict the differences you may or may not hear given you’ll also be changing levels in the rest of your system too.

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Ted,

Thanks for the response. I’ll give it a try and see what happens.

-Alan

If you do the LL1948 transformers with the primaries in parallel I would recommend try it at 94.

Hey Ted

Since you let the Op-amps function as low-pass filters in the MK1 due Edcor transformers having higher bandwidth than you desired, might it make sense to remove this active-filtering functionality from a DS which has replaced the Edcors with some higher-quality, yet lower-bandwidth, input-transformers (such as the Jensens or the Lundalhs)?

The DS ships without the final capacitor in the filter chain that the DS was designed to use. Empirically it sounded better that way at that time. Removing more filtering will sound better for some but for some others that much more high frequency noise might not be welcome - at that point the filtering would be an RC followed by any filtering that the transformer does.

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Thanks @tedsmith !

I understand that much. However, what I’m really asking about is the fact that, so far as I understand it (please correct me if I am mistaken here), the MKIs Op Amps aren’t just buffering, they are also acting as part of an active low-pass filter which sits before the transformers. My understanding is that there are capacitors in the feedback which are performing some active low pass filtering. Is that correct?

The cap which you mentioned above comes at the end of the line. The caps I am asking about are at the beginning of the line.

I was talking about the beginning of the line, R just after the opamps, then C, then transformer, then R.
The original design was opamp (with integrated 2 pole filter), R, C, L, R, C.

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I’m not a moderator and this really is Ted’s thread, but is there any chance you could put these discussions into a thread about modding the original DS, rather than this one?

I keep checking this thread for matters directly related to the Mk II in comparison to the original, and I’m sure other readers are doing the same.

You mean someplace like this Topic: :wink:

My appologies. I wasn’t paying close attention to which thread I was in when I posted above.

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No worries! Even paying attention to the subject and knowing Ted had explained his intent in the opening post for the thread from which this was moved, I’ve been torn about posting some messages. It’s easy to miss that bit of detail…

After much listening, changing the volume controls and attenuator, I decided on the following volume levels:

  • DS 94%
  • mconnect 100%
  • pre amp - about 30% to 50% depending on the recording to get a listen level of 70 db max
  • Attenuator - High (i.e. use lower volume levels on the pre amp)

I didn’t realize there are so many ways to change the volume.

-Alan

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I ran 94 on the DS for a long while. Then dropped backwards to 92 I thought on one of Ted’s suggestions. it seems cleaner. I just tried 94 again. Lost too much inner details. Highs a bit too distorted sounding. Backing off preamp volume no joy. . Back at 92. Much better.

Users’ work on the mod is commendable. However, there has been no movement on software yet. There are definitely members who can do something in the software. I’m looking forward to that day. I think that a software change is needed to suit the mods we make.

I don’t think that will happen. Ted has done an incredible job building the operating system and providing updates. Ted has already stated that he is finished with the updates because he has run out of room / process power the the FPGA used in the DS which in computer chip terms is “OLD” and out of date compared to what’s available today. I don’t see how updating the old FPGA past what Ted has done would make an improvement other then maybe adding some features.

The changes Turbo is making is major surgery and out of the capabilities of most. The only way to properly implement his mods is to create an add on PC board that will piggyback on the original analog board which would include options to keep the transformer or not ( I happen to like what the transformer does in this application) as his design would eliminate DC offset. Also a bi-polar power supply would be needed ether internal or external. I think this is the only solution to get past the already extraordinary sounding mods we currently have implemented. Not software.

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This is dependent on the pre-amplifier used. 94 is -3dB 92 is -4dB. All the DAC’s I have used here have an output equivalent to the DS with the transformer set to 1:2 and the volume set to 94.

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Perhaps it is a function of the volume leveling functions in my preamp to provide even source switching.

I did find out my DS remote seems no longer to be acknowledged. Does anyone have experience in why display no longer lights upon DS when hitting the remote volume. I had to do adjustments from touch screen on volume. The remote will not switch sources on DS either anymore or be used to Dim the display. The remote lights up when buttons are pushed.

Is there a button on DS remote or function that locks it out? Maybe I need to restart everything so DS reads infrared remote signals again.

I am hoping someone else knows how to crack this mystery.

Your symptoms are consistent with the batteries in the remote being low or their contacts being dirty, tho it never hurts to power off the DS with the back power switch now and then.

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