Modding the DirectStream DAC

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because he has run out of room / process power the the FPGA used in the DS which in computer chip terms is “OLD” and out of date compared to what’s available today.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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Make sure you leave the screen at the “input” (i2s, OPT, coax … whatever input you are using) screen before dimming it. If it’s left at any other screen the remote will not function.

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Thanks ted. The batteries are originals though I rarely use the remote. I will try the batteries and power switch.

This sounds like a curious bug. How do you wake it backup? This might be my issue?

Try power cycling. I can simply touch the screen and back out of where I was last.

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Thanks. Going back to the i2S screen playing from the settings screen relative to volume level returned my remote back to functional without a full power cycle. It is funny how if it auto dims on settings screen will leave the DS remote non functioning

I noticed this strange behaviour from the beginning.
Always leave the device at the input selection screen.

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Was told today transformers should ship next week. I’ll keep you updated.

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For about two weeks I’ve been listening to the silver version of the Lundahl transformers (LL1948Ag) installed using a JKRichards adapter board (with the primaries in parallel) in a modded DirectStream Sr.

Mods to DS:

  • LPS Farad Super3 plugged into the analogue board
  • Panasonic Capacitors ECH-U1H153GX5 soldered in C704 position on both transformers
  • Vishay Tantalum Capacitors T58W9476M6R3C0150 soldered over R5 and R6
  • 3M EMI absorber paper AB6005S over suggested parts and used as “fence” around display and Bridge II board

Comparisons:

Edcor XS4400: The Edcor has more pinpointed instruments and vocals. When music was positioned from either left or right speaker, it sounded like the music was coming from the speaker instead of from the instruments or vocalists. The music was more forceful with the XS4400. Lundahls has more dynamics, more detail and has a softer presentation.

Marantz SA7-S1 SACD : Sounded almost like the Lundahls, except the Marantz did not have the dynamics and detail of the Lundahls. Could hear reverb with the Lundahls in the DS that could not be heard using the Marantz SACD player.

Lundahl LL1948Ag: Much more detail and timber from instruments and vocals. It was especially noticeable with John Coltrane’s recordings. The sound stage size seems a little smaller and always between speakers (but maybe I have to listen to more recordings to get a better feel for it). Imaging seems about the same as with the Edcor and Marantz. I could hear more reveb with Lee Ritenour music with the Lundahls. Presentation of Joe Bonamassa Blues music was very well balanced from speaker to speaker. I’m still trying to understand the difference in Orchestral music.

System:
Mconnect application on Samsung S20 → Qobuz w/HiRes → ISO-PLUS Ethernet RF Filters → Ethernet cable → Cheap CSICO Switch covered with 3M EMI paper → ISO-PLUS Ethernet RF Filters → Bridge II → Modded DS → Spectral DMC30SV → Spectral DMA400RS → EgglestonWorks Rosa Speakers. All components except switch are plugged into P20. Room size 21’x17’x8’ with lots of room acoustic treatment. All cables are MIT Oracle MA-X. Speaker cables are Oracle V2.3HR.

Overall, I am very happy with the upgrade. I wish I could hear the difference between the copper and silver versions of the LL1948. Also, it would be nice to know how the mods changed the bit resolution and noise floor.

This is my first round of modding any equipment. Thanks for all the help from everyone and to my electronics shop (Bartlett Electronics in Bartlett TN)!

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Your downfall is the Bridge II. I tested the Bridge II several weeks ago with our Jensen setup and immediately heard the shrinking sound stage and loss of clarity. I temporary remover my Power Board and installed an external power tap on the Bridge II plate to run the analog board of the external power supply so the comparison was fair.

You did not mention if you are running primaries in series or parallel.

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Thanks for letting me know about the Bridge II. I’m going to replace it with the AirLens (when it is released) and use your External Power Controller Board with the Farad Super3.

The primaries are in parallel.

-Alan

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I am thrilled with my External Power Controller / Super3 combo and patiently await my Lundahl’s from Europe. With the Super10 power supply from Farad coming to market shortly, is there any advantage to a higher capability / capacity power supply (over the Super3) for the analog side of our DS’s?

You bought the silver wired version for a 4 digit amount per transformer?

Yep. It was pretty expensive. Not quite four digits, but very close. I wanted to take advantage of the details the preamp, amp, and speakers are able to provide.

-Alan