• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

My question is: a "naked" transformer followed by a diode bridge would have, of course, much worse ripple, but then you filter and regulate. So with a MeanWell you actually start with a better output. The only problem would be the noise spewed before the internal PSU back in the power chain.

So I am curious (and this is for @soekris ) about filtering at power input. I know that the Meanwells have an ingress EMI filter - is this sufficient to not pollute other audio devices?

Roberto

The Meanwell supplies meet all regulations for noise, don't pollute more than your other electronics, doubt you can avoid switchers in your house....
 
More mods

Continuing my mod journey on the 1021. Currently the board has the transistor VREF mod and an additional Audio Note cap added to the 3.3V rail.

First I replaced the 3.3V regulator with a newClassD 3.3V regulator. I also uninstalled the Audio Note cap as newClassD recommends not adding caps at its output.

This mod made the sound smoother and less digital sounding. The bass was also improved and appeared to go deeper. However the highs were somewhat rolled off which reduced the sense of resolution and transparency.

Next I added the Audio Note back to the 3.3V rail and this brought back resolution and improved highs extension. I'd say it returned to 70% of the pre-mod case. The smoothness was retained as well.

So the observation here is that the regulator seemed to reduce noises while the additional Audio Note cap improved highs and resolution.
 

Attachments

  • IMG_2139.jpg
    IMG_2139.jpg
    329.2 KB · Views: 658
As the Audio Note cap improve highs and resolution I took another step and added 4 Audio Note Keiser 100V 100uF bi-polar caps (overkill I know but I have them on hand ...) to the VREF rails.

This brought a major improvement in soundstage, air, resolution, and transparency. This mod is comparable to and could exceed the gain from the transistor mod. I am pleasantly surprised - it seems even the best regulator can benefit from a good cap at the output rail.

After this cap mod it now sounds smoother, with better bass weight and definition, plus improved air, resolution, etc. These mods are very much worthwhile and really take the DAC up a few levels.

(Please ignore the color code in the cap legs as the caps are bipolar.)
 

Attachments

  • IMG_2141.jpg
    IMG_2141.jpg
    428.3 KB · Views: 654
Member
Joined 2000
Paid Member
Jacklee,

Thanks for posting your mods. I have several questions.

You basically replaced the original 3.3v voltage regulator and added a cap to the new regulator's output, correct?
No other changes around the regulator?

Can any 3.3v voltage regulator be directly dropped in?
Looks like you had to rearrange the legs on the regulator, correct?

Where does the regulator output cap drop into the board? I can't see by the photo.

Are the vref caps surface mount or through-hole? Can you provide a close up of the vref caps as they are connected to the board?

Lastly, what is the normal voltage and size requirement for the caps that were replaced?
How many uF can be used in both locations. I think the vref can be as large as possible. I have 6v 2200uF electrolytic organic caps.

Thanks,

Vince
 
Last edited:
Hi Vince,

Please see my replies below:

> You basically replaced the original 3.3v voltage regulator and added a cap to the new regulator's output, correct?
> No other changes around the regulator?

Yes.

> Can any 3.3v voltage regulator be directly dropped in?

I suppose there must be current requirements but I don't recall how much. The newClassD regulator has a current limit of 650mA which should be more than enough. It does run a bit hot (50+ C) so I strapped on a small heatsink to keep it cool at around 40C.

> Looks like you had to rearrange the legs on the regulator, correct?

Yes. I removed the regulator's original pins and replaced them with short silver wires.

> Where does the regulator output cap drop into the board? I can't see by the photo.

The gold-color cap is the output cap. You can see the wires (from left) in the photo. The wires go to the first pair of holes in J9. You can confirm it by checking continuity against GND and the regulator's output pin (middle) or its big tap (same as output pin).

> Are the vref caps surface mount or through-hole? Can you provide a close up of the vref caps as they are connected to the board?

The VREF caps are the 4 big gold-colored caps on the right in the second photo. I bent their leads and soldered them directly to the onboard caps. You can find the cap's location and polarity by Google'ing for "soekris 1021 vref mod".

> Lastly, what is the normal voltage and size requirement for the caps that were replaced?

I didn't replace the original caps. I just added one cap in parallel to the original one in the 4 VREF rails. The rails are either +4V or -4V. If you're using polar electrolytic cap make sure the polarity is correct. NOTE: The red-black color-code in the photo does not correspond correctly to +/- so don't follow that.

> How many uF can be used in both locations. I think the vref can be as large as possible. I have 6v 2200uF electrolytic organic caps.

I read somewhere there is no max limit. Mine is only 100uF. Bigger caps supposedly reduce ripples at lower frequency.
 

Attachments

  • IMG_2142.jpg
    IMG_2142.jpg
    328.9 KB · Views: 612
Last edited:
How easy is it to change modes on the Dam-1021? Can you change from normal to Balanced-Right and Balanced Left on the fly just like changing inputs or is it more involved. I was wondering if I could use 2 - Dam-1021 in balanced mode for 2 channel music and switch to using both Dam-1021's in single ended operation for multichannel use.
 
Signal Polarity Invert for the dac 1541

Soren,

I have had the dac1541 for a couple of weeks now. The sound was a bit raw at first, then became very clean in about a week of being on constantly. Much more enjoyable than what it replaced, an 8 year old [plus 2 newer factory upgrades] MSB. The only thing that the dac1541 lacks is a signal polarity invert choice, most preferably in the digital domain as this will then affect all outputs [balanced or unbalanced, main or headphone] at the same time. Can you find a way to add this feature to this model?

Signal polarity invert in the analog domain at balanced main out can be done using this
Phase Selector switch & PCB for switching between plus-mute-minus
in a small external box. Another box with another of these switches can be made for balanced headphones out. Unbalanced main and headphone out are a different problem, requiring some components plus relays and switches for selection; a small positive aspect here is that this can tap off of the existing power supply in the dac.

Steve
 
Soren,

I have had the dac1541 for a couple of weeks now. The sound was a bit raw at first, then became very clean in about a week of being on constantly. Much more enjoyable than what it replaced, an 8 year old [plus 2 newer factory upgrades] MSB. The only thing that the dac1541 lacks is a signal polarity invert choice, most preferably in the digital domain as this will then affect all outputs [balanced or unbalanced, main or headphone] at the same time. Can you find a way to add this feature to this model?

Signal polarity invert in the analog domain at balanced main out can be done using this
Phase Selector switch & PCB for switching between plus-mute-minus
in a small external box. Another box with another of these switches can be made for balanced headphones out. Unbalanced main and headphone out are a different problem, requiring some components plus relays and switches for selection; a small positive aspect here is that this can tap off of the existing power supply in the dac.

Steve

I'm glad you enjoy the dac1541, like more and more do....

Polarity inverting seems to be something that many, including me, have doubts about the effect.... On the dac1541 I ran out of space for switches and indicators, so I decided not to add it, as I don't see it as something important. So it will not be added to the dac1541, although a future next model might get it, if I can find some real research to support its usefulness...

And please, lets not start a discussion here about signal polarity, but I will check out any pointer to real research....
 
Hi there,

Can anyone confirm or deny the ability of the dam1021 to play 48Khz family DSD? i.e. not 5.644 or 11.2Mhz DSD but 6.144 and 12.288Mhz DSD for instance?

This is the output for example that you get by upsampling a 24/96 or 24/48 file in HQplayer to DSD using auto rate family, which is a lot less processor intensive.

On my unit (OEM part of a DAC) there is only silence with the 48Khz family DSD but not the 44.1kHz familt DSD, which plays just fine.

I do not know the firmware revision of the dam1021.

Thanks!
 
I am planning to use a positive and negative Salas SSLV boards to supply 9V. I was planning to use a transformer with 15VAC secondaries. Could I run another positive board off one of the secondaries or would I have grounding issues? I am using the +/- 9V to feed a Soekris Dam-1021. I was going to use the other to feed a Nordmuss input board with a +8VDC regulated down to 5V and 3.3V to feed the IsolatorPi and Kali Boards and also power the isolated side of the I2S on the Dam-1021. I was wondering if it would be better to run with two transformer instead of just one.
 
I'm glad you enjoy the dac1541, like more and more do....

Soren, I sent an email on your website "info" but never got an answer.

Is it possible on the DAC1541 to get more than 2v from the single ended output, say 2.5v for direct to amp hookup and using the remote volume you say can work with it, (Apple remote i believe)

Cheers George