Why not one of these trannies.
I would choose one of the high imp 10k versions, not 600R. For example a 3293 or better a 3232.
You then have the choice to vary the load by a simple parallel resistor on the secondary side!
Franz
/Edit
And should you buy one: never measure it with an Ohmmeter! The DC will magnetize the core and you have to degauss it. Otherwise you will have high distortion.
I would choose one of the high imp 10k versions, not 600R. For example a 3293 or better a 3232.
You then have the choice to vary the load by a simple parallel resistor on the secondary side!
Franz
/Edit
And should you buy one: never measure it with an Ohmmeter! The DC will magnetize the core and you have to degauss it. Otherwise you will have high distortion.
SPDIF problems ?
Hi there,
I have bought this DAC last month, and I'm overall quite happy with it.
I've tried the output directly from the DAC thing, which on my version, just required to solder a cable after the 1K resistor after the first opamp. I have great results from that from the transparency point of view, but I get a too weak signal, and lose too much dynamics. I have returned to the 2 op amps normal output, with 2xLM4562, which sounds more satisfactory to my ears.
But, on a totally different subject: I have found something strange with this DAC:
I was using it with 2 sources:
-One is an Audio analog paganini CD player, connected to the SPDIF coax input of the DAC.
-The other one is the optical out from a PS3, cascaded through a home theater amp (marantz SR4300): the optical out of the Marantz is connected to the optical input of the DAC. The Marantz is in s-direct mode.
With the Paganini used as the transport, the sound is metallic, harsh, no depth, very much on the clear side.
With the PS3 through the amp, the sound is much better: deep bass, no more agressive highs, etc...
I have been very much surprised by this, as the paganini is supposed to be quite a good transport.
Then I have tried to also redirect the paganini through the amp coax in, and the sound is getting even better than the PS3: more transparency in general, without any problems with the bass or metallic highs.
I have then tried to connect the PS3 straight to the dac, and again, bad sound: metallic harsh, etc...
So I'm trying to figure out what's happening here...
is the amp acting as a buffer, which kind of reformat the SPDIF into something the DAC likes ? Or is the amp resampling the signal (I don't thing it is supposed to do so) ?
I am now trying to use the USB input of the DAC, and it seems to me it not to be affected by the SPDIF problems (but I have moved to another system to get the USB, which is not as resolving, which makes the diagnostic less obvious to my ears).
In short, I suspect there is a problem with the SPDIF inputs of my dac.
I can work around it by passing the signal through the marantz, but it's a pain...
I have read that on certain versions, there is a SPDIF buffer, and some others there is none... could the lack of such buffer be the cause of such a sound degradation through the SPDIF input ? is there anyway to add such a buffer, in case I have none ?
Here is a high res picture of my DAC:
Any help greatly appreciated...
Thanks !
Patrick
Hi there,
I have bought this DAC last month, and I'm overall quite happy with it.
I've tried the output directly from the DAC thing, which on my version, just required to solder a cable after the 1K resistor after the first opamp. I have great results from that from the transparency point of view, but I get a too weak signal, and lose too much dynamics. I have returned to the 2 op amps normal output, with 2xLM4562, which sounds more satisfactory to my ears.
But, on a totally different subject: I have found something strange with this DAC:
I was using it with 2 sources:
-One is an Audio analog paganini CD player, connected to the SPDIF coax input of the DAC.
-The other one is the optical out from a PS3, cascaded through a home theater amp (marantz SR4300): the optical out of the Marantz is connected to the optical input of the DAC. The Marantz is in s-direct mode.
With the Paganini used as the transport, the sound is metallic, harsh, no depth, very much on the clear side.
With the PS3 through the amp, the sound is much better: deep bass, no more agressive highs, etc...
I have been very much surprised by this, as the paganini is supposed to be quite a good transport.
Then I have tried to also redirect the paganini through the amp coax in, and the sound is getting even better than the PS3: more transparency in general, without any problems with the bass or metallic highs.
I have then tried to connect the PS3 straight to the dac, and again, bad sound: metallic harsh, etc...
So I'm trying to figure out what's happening here...
is the amp acting as a buffer, which kind of reformat the SPDIF into something the DAC likes ? Or is the amp resampling the signal (I don't thing it is supposed to do so) ?
I am now trying to use the USB input of the DAC, and it seems to me it not to be affected by the SPDIF problems (but I have moved to another system to get the USB, which is not as resolving, which makes the diagnostic less obvious to my ears).
In short, I suspect there is a problem with the SPDIF inputs of my dac.
I can work around it by passing the signal through the marantz, but it's a pain...
I have read that on certain versions, there is a SPDIF buffer, and some others there is none... could the lack of such buffer be the cause of such a sound degradation through the SPDIF input ? is there anyway to add such a buffer, in case I have none ?
Here is a high res picture of my DAC:
An externally hosted image should be here but it was not working when we last tested it.
Any help greatly appreciated...
Thanks !
Patrick
Thomo said:
I modified 5 of these dacs with Lundahl LL1690 amorphous core. They are great transformers but have to play at least 100 hours to have good sound.
www.lundahl.se/pdfs/datash/1690.pdf
There is an easier mod that occurred to me, and which seems to simulate OK. Leave all the resistor values in place and replace the two brown 100pF capacitors next to the first Op-Amp with 180pF. Then replace the two blue 1nF capacitors next to the dimple on the Op Amp with 180pF. Leave the four 102 (1nF) capacitors in the next row of components next to the DAC, and all resistor values, unchanged and take the output from the output of the first Op-Amp. This will give a reasonable filter shape without having to desolder so many parts.
Kevin
Re: SPDIF problems ?
Yes! There's a problem with S/PDIF in general. It was initially specified as balanced feed at 110ohm impedance with proper professional connectors, but was later dropped to simple and easy to implement 75ohm cable and RCA connectors - and it is by far the worst thing that ever happened to digital audio...
Use 75 ohm (RG59) coax of around 2-3m length.
Use proper isolation transformer - the Sumlink original transformer that was supplied with my DAC is surprisingly good (!!!)
For best performance, use coax-to-TTL conversion before receiver chip - this will require slight PCB modification and one extra chip...
I would advise against version of this DAC that is supplied WITHOUT isolation transformer... if the sound quality is important... or, add one yourself and keep the USB interface....
There's a resistor on your photo associated with +12V supply, that shows signs of burning...
Boky
vazymonga said:
Yes! There's a problem with S/PDIF in general. It was initially specified as balanced feed at 110ohm impedance with proper professional connectors, but was later dropped to simple and easy to implement 75ohm cable and RCA connectors - and it is by far the worst thing that ever happened to digital audio...
Use 75 ohm (RG59) coax of around 2-3m length.
Use proper isolation transformer - the Sumlink original transformer that was supplied with my DAC is surprisingly good (!!!)
For best performance, use coax-to-TTL conversion before receiver chip - this will require slight PCB modification and one extra chip...
I would advise against version of this DAC that is supplied WITHOUT isolation transformer... if the sound quality is important... or, add one yourself and keep the USB interface....
There's a resistor on your photo associated with +12V supply, that shows signs of burning...
Boky
Thanks a lot Boky for your suggestions. I'll look for adding a transformer AND the TTL circuits.
If you have any parts and schema you can recommend me, I would more than grateful.
Yes, I had noticed the resistor overheat after taking the picture. I'll have to look into that as well: I think my transformer is a bit higher than the recommended 12-15V (I have measured 16.4V). Could it be due to that ?
Patrick
If you have any parts and schema you can recommend me, I would more than grateful.
Yes, I had noticed the resistor overheat after taking the picture. I'll have to look into that as well: I think my transformer is a bit higher than the recommended 12-15V (I have measured 16.4V). Could it be due to that ?
Patrick
Hi all,
I also have bigger version with cs4398 on board(probably the same like Franz).
Can some one explain me why we need output stage with opamp, tube or transformer or what ever it is?
OK,we need some buffer to protect cs output or we do not need?
Why we need to filter something(DAC already contain some filtering stage)? Or we need filter stage only with opamp output.
This DAC has Vout. So I connected DAC output directly to my preamp(rotel 1090). Signal level is little lower, but at least it sound better and at this connection point( -L and -R) I have real CS DAC sound. What advantage give me additional stage(tube,transformer)?
Regards,
Darius
I also have bigger version with cs4398 on board(probably the same like Franz).
Can some one explain me why we need output stage with opamp, tube or transformer or what ever it is?
OK,we need some buffer to protect cs output or we do not need?
Why we need to filter something(DAC already contain some filtering stage)? Or we need filter stage only with opamp output.
This DAC has Vout. So I connected DAC output directly to my preamp(rotel 1090). Signal level is little lower, but at least it sound better and at this connection point( -L and -R) I have real CS DAC sound. What advantage give me additional stage(tube,transformer)?
Regards,
Darius
Kevin Wood said:
Thanks for the hint Kevin, i simulated the LPF with the original value, your proposal and another solution with little effort of desoldering and resoldering.
Here the LPF photo with the label used in the simulation:
An externally hosted image should be here but it was not working when we last tested it.
The simulation with original values (only one channel):
An externally hosted image should be here but it was not working when we last tested it.
Kevin proposal:
An externally hosted image should be here but it was not working when we last tested it.
Another option:
An externally hosted image should be here but it was not working when we last tested it.
Here C1, C2, C4, C6 (1nF) are removed and C3, C5 substituted with the 82pF brown capacitors taken from the second opamp.
Ciao
Andrea
udovdh said:
Looking the simulation (post #229) and the measurements (post #212) the frequency responce with the original parts is not optimal, much better with the other two modifications proposals.
Anyway till now i only have listened the DAC with original parts and it sounds no bad at all, when i will do the mods i will report my impressions.
Ciao
Andrea
johnm said:
Here is the simulation with the value from Application Note 48 from Cirrus Logic:
An externally hosted image should be here but it was not working when we last tested it.
Ciao
Andrea
My first listening opinion, after some hours of listening with the output trannies:
The upsampling configuration does fatigue. I mean, a lot of details, but the musicality is somehow missing.
Using the nonupsampling configuration, the sound is a little bit dull, compared to the upsampling version.
But some kind of more "musicality".
Sorry, with my limited english knowledge, it is hard to describe the impressions.
But I still prefer the Studer D731 or vinyl, played on my EMT930 turntable by a TSD15 cartridge.
Conclusion: I will try different kinds of filters after the output trannies. Imho still needed.
Franz
/Edit
Maybe I have to add this information: actually, I am using the DAC with TOS-link connected to the PC. To be fair, I should make a fine SPDIF input with BNC connector and input tranny.
The upsampling configuration does fatigue. I mean, a lot of details, but the musicality is somehow missing.
Using the nonupsampling configuration, the sound is a little bit dull, compared to the upsampling version.
But some kind of more "musicality".
Sorry, with my limited english knowledge, it is hard to describe the impressions.
But I still prefer the Studer D731 or vinyl, played on my EMT930 turntable by a TSD15 cartridge.
Conclusion: I will try different kinds of filters after the output trannies. Imho still needed.
Franz
/Edit
Maybe I have to add this information: actually, I am using the DAC with TOS-link connected to the PC. To be fair, I should make a fine SPDIF input with BNC connector and input tranny.
Andrea,
Thanks for sharing your simulation results and the picture showing component numbers!
It looks like the simplified mod described by Kevin could be good enough for a lot of people, a 0,5 dB drop at 20kHz isn't really that much to argue about from a technical stand point. I won't allow myself in to new argument of how different solutions sound...
Thanks for sharing your simulation results and the picture showing component numbers!
It looks like the simplified mod described by Kevin could be good enough for a lot of people, a 0,5 dB drop at 20kHz isn't really that much to argue about from a technical stand point. I won't allow myself in to new argument of how different solutions sound...
Segran said:Andrea,
Thanks for sharing your simulation results and the picture showing component numbers!
It looks like the simplified mod described by Kevin could be good enough for a lot of people, a 0,5 dB drop at 20kHz isn't really that much to argue about from a technical stand point. I won't allow myself in to new argument of how different solutions sound...
Segran (and Kevin),
what do you think of the other mod proposed by me with -0.5dB at 20KHz and slow rolloff of 6dB per octave (vs 12dB per octave of the other mods)?
Ciao
Andrea
Andrea,
personally I don't think I could hear any significant difference between the two - but testing would have to prove if my assumption is right or wrong! I'm not qualified for that test, my hearing ends at 16kHz....
However, as I understood Kevins post his proposal was mainly aimed at not having to desolder/re-solder as many of the cap's that are connected to the ground plane due to the difficulties involved.
personally I don't think I could hear any significant difference between the two - but testing would have to prove if my assumption is right or wrong! I'm not qualified for that test, my hearing ends at 16kHz....
However, as I understood Kevins post his proposal was mainly aimed at not having to desolder/re-solder as many of the cap's that are connected to the ground plane due to the difficulties involved.
johnm said:Thanks for the advice Fritz - I'll remember that
Just as an aside, why are these transformers so pricey compared to - for example - small mains transformers?
These transformers require a flat frequency response over a wide bandwidth, rather than just at one particular frequency. To provide this frequency response, it may require a design that is more difficult to manufacture. Also, they need to be sheilded to prevent outside interference and should have tight tolerances to prevent variances between channels. They're also made in smaller quantities than power transformers, so there's increased cost with smaller economies of scale.
Thanks for the filter options and opinions.
What about using 'discrete opamp' with this DAC?
Or Zapfilter?
Would that change much? In what regard?
Please comment.
I do have experience with a ZHaolu D2.5C w/ Zapfilter and I'd gladly compare.
What Lawrence case would fit these DAC boards best? (possibly also Zapfilter or at least 2nd transformer and headamp)
What about using 'discrete opamp' with this DAC?
Or Zapfilter?
Would that change much? In what regard?
Please comment.
I do have experience with a ZHaolu D2.5C w/ Zapfilter and I'd gladly compare.
What Lawrence case would fit these DAC boards best? (possibly also Zapfilter or at least 2nd transformer and headamp)