That's awesome. I need to finish my tda dac.
I'd like to see how you laid it all out in the separate units.
Hello to everyone,
I am about to finish my Red Baron v5.0 DAC. I'd like to go with Mosfet Buffer version first, before I'll try tube output (Sowter 8347 I/V transformer and then E810F or 4P1L according to I/V resistor value).
The question about Mosfet Buffer is if I can use higher value of I/V resistor than 500R? Let's say 1k to get 1.4Vrms or 1k5 to get 2.12Vrms? What about Reference GND? May I use 3.3V DC Digital source? Or use 5.0V as in RedBaron v4.0? Or maybe higher: 10VDC or 15VDC according to higher I/V resistor?
Best regards,
mhgawel
I am about to finish my Red Baron v5.0 DAC. I'd like to go with Mosfet Buffer version first, before I'll try tube output (Sowter 8347 I/V transformer and then E810F or 4P1L according to I/V resistor value).
The question about Mosfet Buffer is if I can use higher value of I/V resistor than 500R? Let's say 1k to get 1.4Vrms or 1k5 to get 2.12Vrms? What about Reference GND? May I use 3.3V DC Digital source? Or use 5.0V as in RedBaron v4.0? Or maybe higher: 10VDC or 15VDC according to higher I/V resistor?
Best regards,
mhgawel
Hi,
i have changed the design a little bit. Only the Tube PSU is now in a separate box because the power rails for the TDA DAC was to long and its was an unflexible cabling. at this time i play a little bit with the tube psu LCLCLC with PIOs filtering without regualtion or lclcrc with regulation, sshv2 or tube regulator. there be a lot of things we can do. if i have sucess than i will post more details andinformations.
best regards
Karsten
i have changed the design a little bit. Only the Tube PSU is now in a separate box because the power rails for the TDA DAC was to long and its was an unflexible cabling. at this time i play a little bit with the tube psu LCLCLC with PIOs filtering without regualtion or lclcrc with regulation, sshv2 or tube regulator. there be a lot of things we can do. if i have sucess than i will post more details andinformations.
best regards
Karsten
I'm sorry I can't answer your question but PLEASE keep us updated on your progress with the tube output stages. I'm using the Baron with D3a tubes and plate chokes powered by Salas SSHV2 shunt regulators and it is absolutely great. The best digital sound I've ever heard. But of course there is always something better out there and DHT's in the output stage has always been a dream of mine. Signal/Noise ratios and a potential lack of dynamics has kept me from it but please prove me wrong.
Kind regards,
Vidar
The problem is that my idea of using very low value I/V resistor, Sowter 8347 transformer and high-mu triode-strapped pentode is not good. I wanted to use 500R I/V resistor connected to transfomer secondaries. It would be reflected on the primaries side with the ratio 18.7^2=350x, so the I/V load about 1.4R. Unfortunately I/V load lower than 6.25R to stay in TDA1541A voltage compliance range is too small for good performance of the transformer (25R is datasheet IV value for 8347 transformer).
So... I have all the parts on my desk but the idea is wrong
Another thing is that there's now a new R2R discrete DAC from Soekris available and I hesitate between finishing Red Baron and buying Soekris DAC.
But if I make any progress then I'll share my experiences.
Regards,
Maciek
Hi,
What are the values you choosed to make the D3A stable ? (not too much third harmonics ? Did you measure with a scope and compare many settings with this tube ?)
Would like use such ref tube à la Thorsten but is it possible to set up it without scope ? Or is there a good scheme to use such D3A tube new from shelf ?
Are DHTs not too hummy for a dac chip ? Certainly a wise idea to avoid its !
Sorry off topic, maybe a link or just a shematic could be fine whatever the dac board used if TDA1541 chip only ?
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I do not have the knowledge to make things completely from scratch but I try to improve it as best I can.
The operating points of the D3a is kept as per schematics "published" by Ceglar in the Ultimate 1541a thread here at Diyaudio. The design is by Thorsten Loesch and uses CCS'es. However - the sound improved significally with anode chokes and SSHV2 shunts from Salas. I tried the shunts from K and K audio and the SSHV2's was much better.
I bought mached D3a's from Turkey and they are working very well indeed.
Sorry - no measurements of the output stage but it is incredibly quiet and it sounds excellent. I guess a couple of ferrite beads and carbon resistors, a B+ of 60V and 10mA current through the tube makes it stable.
The operating points of the D3a is kept as per schematics "published" by Ceglar in the Ultimate 1541a thread here at Diyaudio. The design is by Thorsten Loesch and uses CCS'es. However - the sound improved significally with anode chokes and SSHV2 shunts from Salas. I tried the shunts from K and K audio and the SSHV2's was much better.
I bought mached D3a's from Turkey and they are working very well indeed.
Sorry - no measurements of the output stage but it is incredibly quiet and it sounds excellent. I guess a couple of ferrite beads and carbon resistors, a B+ of 60V and 10mA current through the tube makes it stable.
Thank you.
Well done, believe evil is in the details and tips help a lot !
I have this shematic. I will ask to Ceglar if I need details, I hesitate myself for an easier tube to work with, again than T. Loesch uses himself at home. Don't want to high jack the thread of Oliver, but please if you have the link of your shop in Turkey for the matched pair I'm interrested...(did you controll the matching ?): you can use my diyaudio PM if you have time.
It's a long term project : have to learn more
, buy the parts little by little.
regards
Well done, believe evil is in the details and tips help a lot !
I have this shematic. I will ask to Ceglar if I need details, I hesitate myself for an easier tube to work with, again than T. Loesch uses himself at home. Don't want to high jack the thread of Oliver, but please if you have the link of your shop in Turkey for the matched pair I'm interrested...(did you controll the matching ?): you can use my diyaudio PM if you have time.
It's a long term project : have to learn more
, buy the parts little by little.regards
I don´t see any problems to use them also at this position.
Thanks a lot for the answer.
I soldered them, then desoldered
And now I solder them back
I've bought two Squaristors 1K5 0,01% recently and they cost GBP39.43
Item Sku Qty Subtotal
GG102A 1.5K 0.01% GG102A 1K5 2 £15.86
Subtotal £15.86
Shipping & Handling £17.00
Grand Total (Excl.Tax) £32.86
EU VAT Poland (20%) £6.57
Tax £6.57
Grand Total (Incl.Tax) £39.43
Best regards,
Maciek
Hi,
the stock is down atm, because of the USD/EURO exchange rate.
I must thinking about a price correction for all pcb´s, because i don´t see that the EURO comes up in the near future.
Stay tuned and keep an eye in my blog.
Best regards,
Oliver
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