Well Bob... in fact an upgrade has been done... the MC7812/MC7912 are an important part of the upgrade BOM...
Hi ClaveFremen,
Is out of the topic but can i stack(parrallel) two nos MC7812 to get 2A for output?I afraid to try it may damage the dac.
Thank
Hi Tomes,
No, you cannot stack the MC7812 parallel to get 2A.
But why do you need 2A? The kit It uses 300-500 mA on the +12V side (only one side, the -12V does not). So just follow the BOM of Darius, and put a heatsink on it. That is enough.
And if you use a 2 x 14V transformer it get's less hot, than if you use 2 x 18V.
No, you cannot stack the MC7812 parallel to get 2A.
But why do you need 2A? The kit It uses 300-500 mA on the +12V side (only one side, the -12V does not). So just follow the BOM of Darius, and put a heatsink on it. That is enough.
And if you use a 2 x 14V transformer it get's less hot, than if you use 2 x 18V.
Having tried a couple of different op-amps and not seen the same heat problems with the op-amp or the power regulators it does seem to be specific to the THS4032CD so I'll give the decoupling caps a go.
That's a tricky task when using a surface mount device that's been adapted to fit a standard DIP socket. I'll see what I can do but maybe the THS4032CD isn't a good match for this application.
finally, made few pics of mine
2/3 has been done according to Dario's BOM.
Added salas for +-12v and +5v and Dario's shunt with BD139 (now it's ok, it shows 8.6v with 8.2v zener) for +3.3v
Digital part has 2x2200uf BC caps now and one 2200uf for A+3.3
2/3 has been done according to Dario's BOM.
Added salas for +-12v and +5v and Dario's shunt with BD139 (now it's ok, it shows 8.6v with 8.2v zener) for +3.3v
Digital part has 2x2200uf BC caps now and one 2200uf for A+3.3
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you really need to sort that out with a shroud or something. Your whole system is in danger of becoming LIVE!!!!!!!!!!the case is closed all the time, what is lethal? I don't see any point puting some insulation, correct me if I'm wrong....
the case is closed all the time, what is lethal? I don't see any point puting some insulation, correct me if I'm wrong....
An easy way is to squirt silicone sealer on the bare terminals.
My ready built dac has all wired connections covered in it.
Most of the kits I've been buying from China come with female disconnects and a nice silicon sleeve that is removable. Since then I sourced 100 of them from my preferred vendor over there. (Note: He's been very reasonable on extra parts I've asked about that he doesn't list seperately.) Those have been very hard to find from my suppliers in the US. I have since been using the female disconnects and sleeves on all my IEC mains socket, switch, fuse and PSU connections. Of course those items need to have the male push on tab connector. Keeps things a little more safe inside the box from a wandering probe.An easy way is to squirt silicone sealer on the bare terminals.
My ready built dac has all wired connections covered in it.
A week ago, we tested my DAC compared to the CD player Unico Primo. At the first, test, the impressions were:
-awesome dynamics, no distinction between the CD and the DAC
-awesome instrument spacing,
-detail.. well, awesome bass and low mids, but in the high mids and lower highs - something like overdetailed information that was harsh and not pleasing to the ear.
The guy was very nice, he brought a big box full of tubes. We started swapping, beginning with the voltage amplifying tubes first.
Changing the Hytron 5814WA with the RFT ECC82 made a very big improvement - bigger, but controlled bass and much less harsh mids and treble. Music started to sound nicer.
It was already 01 AM. We decided to swap the output current amplifying tubes with 12BH7.
Then - WOW! All the harshness gone! Musicality to the top! We compared to the CD player again and the DAC was so dangerously close to it. The dynamics were there. The spacing was there. The musicality and gentleness was there. Only a veeery slight micro detail was lacking.
The guy was very happy and he liked the DAC a lot.
I am also happy, because I know the DAC can be upgraded further and has potential. Compare the costs: - I spent about 150 USD for my DAC for now, while the CD player costs about 2000USD average.
Well, of course the DAC is DIY and has no CD and mechanical stuff in there.
Swapping the tubes increased the B+ and the bias of the voltage amplifying tubes. I measured that the ECC82 are biased into -8,5V and the anode current is about 12-13mA
The DAC in its curent setup now:
-AK4396
-Salas 5V analog shunt to the DAC
-The unbalancer modified by me. The modifications are: second decoupling cap to make the two stages potential independant, no CCS but a simple cathode resistor
-Tubes: RFT ECC82 voltage stage and 12BH7 output current stage
-Modified (stripped off) coupling PIO russian caps K40-U9 and output russian tantalums ETO-3 (K52-2)
-Cy LCCxLCLC filtering, EZ81 rectifiers Cy = 47uF, Cx=100uF, C=4uF non-electrolytics L=5H
-awesome dynamics, no distinction between the CD and the DAC
-awesome instrument spacing,
-detail.. well, awesome bass and low mids, but in the high mids and lower highs - something like overdetailed information that was harsh and not pleasing to the ear.
The guy was very nice, he brought a big box full of tubes. We started swapping, beginning with the voltage amplifying tubes first.
Changing the Hytron 5814WA with the RFT ECC82 made a very big improvement - bigger, but controlled bass and much less harsh mids and treble. Music started to sound nicer.
It was already 01 AM. We decided to swap the output current amplifying tubes with 12BH7.
Then - WOW! All the harshness gone! Musicality to the top! We compared to the CD player again and the DAC was so dangerously close to it. The dynamics were there. The spacing was there. The musicality and gentleness was there. Only a veeery slight micro detail was lacking.
The guy was very happy and he liked the DAC a lot.
I am also happy, because I know the DAC can be upgraded further and has potential. Compare the costs: - I spent about 150 USD for my DAC for now, while the CD player costs about 2000USD average.
Well, of course the DAC is DIY
and has no CD and mechanical stuff in there.Swapping the tubes increased the B+ and the bias of the voltage amplifying tubes. I measured that the ECC82 are biased into -8,5V and the anode current is about 12-13mA
The DAC in its curent setup now:
-AK4396
-Salas 5V analog shunt to the DAC
-The unbalancer modified by me. The modifications are: second decoupling cap to make the two stages potential independant, no CCS but a simple cathode resistor
-Tubes: RFT ECC82 voltage stage and 12BH7 output current stage
-Modified (stripped off) coupling PIO russian caps K40-U9 and output russian tantalums ETO-3 (K52-2)
-Cy LCCxLCLC filtering, EZ81 rectifiers Cy = 47uF, Cx=100uF, C=4uF non-electrolytics L=5H
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Try an autoparts store, you should be able to get insulated female spade connectors there. Probably not silicone but equally as effective, especially if you need to plug/unplug it. Otherwise I just solder the connection and insulate it with shrink wrap sleeving.
I did. My local AutoZone wanted about $3.50 for 8 insulated disconnects. Highway robbery in my book. Instead, I bought exactly what I wanted from my supplier. $6.00 for 100pcs.
Here ya go... He doesn't list these directly in his eBay store, but he will sell to you via email. Most of the stuff I've bought from China has come from this site. I was hoping I wouldn't have to go to him for small parts like this, but instead find them at the big box suppliers like those mentioned by haik. I just have a hard time trying to navigate their sites sometimes and find exactly what I want. Don't get me wrong... I still order $$ from Mouser, Newark/element and Digikey.