.... and 5 Hz an a good average HPF targett for this DC blocking.
As we are at it, how much V should be the cap acording the tube output ? X 1.5 enough ?
As we are at it, how much V should be the cap acording the tube output ? X 1.5 enough ?
That's what i use with E188CC (low noise ECC88), 150V tin foil works fine, thiner foils can have good result for the sounding behavior according the transparency of your system.
Hello everyone, I'm about to join the miro DAC club! I got this populated miro PCM63 board + the jlsounds board from @zoom777 . I made my own more-compact version of the PSU2 and stuffed that today. I got it all wired up, and it's working great! All that's left to do is order a chassis and to stuff my +/- 12V PSU2 to power the AD797 I/V stage separately. Here's a picture of the pre-chassis rat's nest.
@carlman14 Thats how a DAC should look like, no need to case up, leave as is 😉
Zoom builds a solid DAC, his work is very good. I really like the PCM63, musical DAC. Nelson Pass used them, can't be that bad...
Zoom builds a solid DAC, his work is very good. I really like the PCM63, musical DAC. Nelson Pass used them, can't be that bad...
The board is indeed very well put together. I chose a PCM63 build because a while back, I bought a pair of brand new K-graded PCM63s from ebay for a grand total of $8. I was always skeptical if they were legit despite looking real, and I'm glad I finally get to test them. They are in fact legit! Probably the best deal I've gotten on something audio-related.
Its time to start putting the DAC in a nice enclosure and I am thinking through the grounding map. Based on this article https://www.diyaudio.com/community/threads/audio-component-grounding-and-interconnection.163575/ I put together attached draft. I think analog ground should only be connected to the ground of the analog power on the DAC PCB (3). The digital ground I think should be connected to the ground of the FIFO's 3V3 (2) and to the ground of the FIFO's 5V (1). IanCanada's FIFO provide galvanic isolation, however, I am not sure if the ground is isolated as well. If it is, the 5V ground (1) probably should not be connected to the digital ground. The PurePi uses LiPo to power 3V3 circuits of FIFO. I don't think RPi and display need to be connected to the digital ground. I think the output RCAs should not be connected to the chassis.
I am sure I made mistakes and I would greatly appreciate your input.
I am sure I made mistakes and I would greatly appreciate your input.
What is the max B+ for Grunf's Tube I/V board and power supply?
Just asking as I have two unused power transformers that I wonder if I can use, or if I need to buy a new one.
The ones I have:
0-240Vac 60mA + 6.3Vac 1.6A
&
0-200Vac 30mA + 6.3Vac 1.1A
That's quite a bit higher than the 0-130Vac recommended 😅
But can one of them be used?
Just asking as I have two unused power transformers that I wonder if I can use, or if I need to buy a new one.
The ones I have:
0-240Vac 60mA + 6.3Vac 1.6A
&
0-200Vac 30mA + 6.3Vac 1.1A
That's quite a bit higher than the 0-130Vac recommended 😅
But can one of them be used?
PSU caps and tube will determine max. The standard build here uses 200/250V caps. I have 130V trafo which gives around 185 at the board for 200V caps.
The 200V you have will give 285V DC, 6DJ8 datasheet shows 330V max. 😉
30mA is on the limit however, the pre-amp type tubes use around 22-25 according to datasheets. It will work.
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It looks like I'll need to buy or trade for a transformer as none of my tube power transformers is centre tapped
From the question above (a few posts up) I kinda jumped to the conclusion that was needed
I am in the process of experimenting with different IV stage setups, Vunce's IV, discrete OPA627, CEN/XEN and considering building tube IV stage shared by you. One of the biggest putoff form me about TDA1541 is the on/off thump, have you catered for it in the tube IV stage.
@miro1360 shared a DC offset circuit but unfortunately it doesn't seem to work for me. Once I connect it to the DAC there is no output after the DC offset stage, maybe I need to start reading about UPC1237
One of the reasons I still prefer AD1865 or AD1862 over TDA1541.
Oh crap, none of my high voltage transformers has more than one secondary for B+ and one for heater.
I'll have to get a new one anyway then