Thanks, thats a possibility yes. But I`m beginning to get so tired of this preamp so I have to get it fixed and try to sell it. Noone will buy a preamp thats not original anymore.
Thanks. It is my own design (after reading many literature).
Do you think to remove R12, and use only R4 in my schematic? I supply VT3 through them (and also G2).
I use EF80, because I have them a lot lot lot 🙂 But also EF184 is common in my stock, so if I will return to this project once, I can try.
I read about CCS, do you have any hints how to? Thanks
I have already finished my PCB some years ago, but not using a lot, cause I still missing some enclosure (and without it, as you know, hum occur). But I glad to look on the other way how to design simple and effective regulator 😉
Beacuse we want? 🙂
I used not only common EZ8x, GZ34,... but I am successful also with rectifiers like PY88, 6c10p, etc.... btw. 6c10p is very nice choice for e.g. EL84 PP...
It's not the heater-cathode voltage out of range (is only about 35V here) but the currents in the ECC82 are much to low.
Try with a ECC83 (12AX7) not optimal but much closer.
Mona
Cascade filtered power supply.
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The schematic does not reflect the PCB. As Ketje wrote, the PCB is for an E88CC (ecc88, 6DJ8,6N23S) heater wiring. An ECC82 will get only half of its heater voltage thus the hum.
Did you try one of the above tubes? Did the schematic came with the pre-amp? I would be surprised.
Excuse me for saying, but does any of you guys bother to read the whole tread.
The pcb was initially made for ECC88 but Wall changed it to ECC82. So I did too. But as said in #36 the heater is now made for ECC82. IF you care to help, please don't be hung up in all kinds of chit chat about things that have nothing to do with the problem itself.The schematic is made by me and it's absolutely correct drawn.
I want to re-design and improve schematic from post
https://www.diyaudio.com/forums/tubes-valves/348318-tube-regulator.html#post6050633
any sugestions? I need at the output +200V. Probably I will try EF184, and supplu G2 of pentode from B+ before regulator.
Thanks.
You could order some of these boards if you want, I will post gerbers if you need them.
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That's the one I have too right? works great and it will most likely end up in my preamp once I get to it
OK, if the schematic reflects the circuit board correctly (after adaptation for the ECC82 heater was done), than it's a very weird design (maybe a faulty circuit board?).
The 6C19P is biased positive by R14 (the connection to the internal screening of the EF80 doesn't influence the bias of the 6C19P). So it will just pass current.
The EF80 is connected as a triode, in which g2 functions as the anode (g3 and plate are connected to the cathode).
The ECC82 is not controling the 6C19P but only the EF80 (because control via the connection from the outer screening of the EF80 to the grid of the 6C19P is not possible).
So it looks to me that the EF80 could only be functioning as a kind of ripple killer. I find it hard to see how you can adjust the output voltage with R16. It will influence the amount of current flowing through the EF80, but so very little that it can hardly inluence the output voltage.
I looked a bit if the circuit board was maybe made for another tube than the EF80, but I couldn't find something in this direction.
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You would get rid of nearly all the hum if you bypass R15 maybe at least a 4.7uf
Use a low pass filter for a cleaner reference to the 12AU7, and connect the screen grid of the EF80 to a voltage divider between the 67K and the cathode reference Zener. Probably a 47K and 10K connect the screen between these two, much more gain and better regulation from the EF80. Before the regulation was about 0.1%(triode connected), with more gain you would get closer to 0.01%
One might even use a 12AT7 instead of 12AU7, giving more gain in the error amp.
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If A1008 is still here, try put a 68k between C8 and C9.
It's no solution for the problem but could be a cure for the hum.
Mona
It's no solution for the problem but could be a cure for the hum.
Mona
I'm not surprised. Tell me you didn't pay almost $7,000 for that PoS. I have never seen such a foxed up design. ( I really should have gotten into audiophool grifting as a profession. 😀 )
In the first place, a 56uF reservoir capacitor is too large for a hollow state diode. The Isurge rating is quite low as compared to solid state diodes and it's all too easy to bust that spec. A hollow state power supply needs a smaller reservoir and an LC low pass filter.
The active regulator looks overly complicated and makes no sense. It also doesn't have a stable voltage reference, and so won't perform very well. I'd scrap the whole damn thing and start over. Reduce the reservoir to about 34uF (two 68uF/350V capacitors in series with voltage balancing resistors) a 10H filter choke and a 220uF capacitor behind the choke, and a simpler, but more effective, active regulator. I did this design (attached) for the Le Renard project as a screen voltage regulator. The 6AQ5 is over rated for this application, so may work just fine for a preamp. You could use one or more 6AS7s for the series pass device if you need moreamps.
