My R12 only drops about 3v after I reduced it. You can experiment with B+ depending on which tubes you are using.
I am about tofiit four x 6N2P which are not listed in the manual so may need to adjust the HT as well as alter the heater links from 12v t to 6,3v in series..
Double check that the 12v windings are completely separate as the description is unusual - commonly the manufacturers would state 2 x 0-12v or 0-12v twice.
I am about tofiit four x 6N2P which are not listed in the manual so may need to adjust the HT as well as alter the heater links from 12v t to 6,3v in series..
Double check that the 12v windings are completely separate as the description is unusual - commonly the manufacturers would state 2 x 0-12v or 0-12v twice.
1. R12 resistor on the ps-21 controls the dc volts to the 6sn7 heaters yes? 2. R12 on the octal board controls the voltage to the 6sn7 plates. yes?
3. R12 according to the manual shows 499 ohms for 6.3vdc output yes?
4. my transformer for heaters dual 12vac in parallel and 24vac ct
5. The transformer for the B+ is 240ac single-winding..is this ok?
what is the limit on how much B+ higher is better? how do I measure? ..what should I see at the plate? these are my transformers. 546-1182L12 and 546-1182E240
3. R12 according to the manual shows 499 ohms for 6.3vdc output yes?
4. my transformer for heaters dual 12vac in parallel and 24vac ct
5. The transformer for the B+ is 240ac single-winding..is this ok?
what is the limit on how much B+ higher is better? how do I measure? ..what should I see at the plate? these are my transformers. 546-1182L12 and 546-1182E240
Choose the B+ according to the table in the Aikido manual and then select R6 & 7 from the table on page 8 of the PS21 manual.
So I use R12 = 1.13k as I was using tubes with 12,6v heaters.
So I use R12 = 1.13k as I was using tubes with 12,6v heaters.
thank you. what resistor do I select for r12 on the octal board? how much B+ should I have with the tubes plugged in or unplugged? the transformer is a 240vac single secondary. I am using all 6sn7 tube.s
Crooner,
Take a picture of the octal schematic and show us.
What B+ voltage are you aiming for out of the PS-21 board?
Cheers, S.
Take a picture of the octal schematic and show us.
What B+ voltage are you aiming for out of the PS-21 board?
Cheers, S.
Which tubes will you be using?
Same for input and outputs?
If you set the heater voltage to 12v, and have tubes with 6.3v heaters, then these must be wired in series and all 4 must be the same type.
Otherwise 499R for R12 for 6.3v and set jumoers for paralellel heaters.
Same for input and outputs?
If you set the heater voltage to 12v, and have tubes with 6.3v heaters, then these must be wired in series and all 4 must be the same type.
Otherwise 499R for R12 for 6.3v and set jumoers for paralellel heaters.
Mulitply the Ik from the table by four to get the total current, and find R12 from the table. So the value will depend on what you set B+ to on the PS21, compared to what you want on the Aikido.
That's the question. what do I want to see on the aikido ..what is the sweet spot? the 6sn7 tube can handle 450vdc yes?... R 3,4,6,7 are 470 ohms I believe these are the cathode resistors............ how do I measure B+
should I measure the tube plate voltage at the plate of the tube with the tubes installed? would 300vdc be a good target?
Given your lack of knowledge, perhaps you shouldn't be building something with potentially lethal voltages.?
My Aikido uses noval tubes so can't help with octal ones.
My Aikido uses noval tubes so can't help with octal ones.
I didn't know there was going to be so many options. I am new to tubes. I think a much better purchase for me would have been the tubes for the HIFI preamp kit which is a little more straightforward for a new bee like me.
thanks to all on the site who have chimed in. I appreciate all the help. In the end, all these projects work out for me somehow.
What gain do you need as this will dicate the choice of tubes? For example a 6SL7 has a gain of 70 whereas a 6SN7 , it's 20.
Then choose a middle of the road B+ voltage.
A 240vAC transformer gived about 334v raw HT on load with full bridge rectification which is regulated down to 300, 250, or whatever.you want,
If you allow for a voltage drop of say 20v across R12 on the Aikido board, then you have a simpler way to adjust B+ than altering the PS21.
You only learn by doing and by researching line stage preamps.
Then choose a middle of the road B+ voltage.
A 240vAC transformer gived about 334v raw HT on load with full bridge rectification which is regulated down to 300, 250, or whatever.you want,
If you allow for a voltage drop of say 20v across R12 on the Aikido board, then you have a simpler way to adjust B+ than altering the PS21.
You only learn by doing and by researching line stage preamps.
I don't need that much gain. will probably use all 6sn7 tubes. I am waiting for my transformers. I temporarily hooked up a 12vac wall wart that was rated at 1.3a to my PS21 and sure enough I am getting 6.3 VDC on the output of PS-21. ...so I think that the heaters will be in parallel with each other...2 per winding. YEAH, I will shoot for 300vdc for B+ and then check the current draw on the cathode.
If you are going to parallel the filaments for 6.3 volt operation then feeding the filament supplies with a 12vac transformer is probably not optimum. Raw rectified DC will be in the region of 17 volts so the LD1085 will need to drop 10 volts or more and will generate a lot of heat.
A trans with a 9 volt secondary will still give you 6.3 volts regulated DC but will reduce stress on the LD1085.
Using all 6SN7s will give the sort of gain needed for a line stage. 6SL7s in the first position will result in too much gain.
Regarding my comments earlier of filament supply negative tied to a portion of the B+ : You can ignore what I said as this is handled by resistors R13, R14 and C1 on the Aikido board.
Regarding R12 on the octal board: I believe, the wide range of resistors supplied for this position is to accommodate running from a wide range of supply voltages, especially from an unregulated supply. As you will be using a regulated supply, I'd aim for about 300 volts out of the reg. supply so the value of R12 on the board can be quite low. Start with 300 ohms and see how it goes.
S.
A trans with a 9 volt secondary will still give you 6.3 volts regulated DC but will reduce stress on the LD1085.
Using all 6SN7s will give the sort of gain needed for a line stage. 6SL7s in the first position will result in too much gain.
Regarding my comments earlier of filament supply negative tied to a portion of the B+ : You can ignore what I said as this is handled by resistors R13, R14 and C1 on the Aikido board.
Regarding R12 on the octal board: I believe, the wide range of resistors supplied for this position is to accommodate running from a wide range of supply voltages, especially from an unregulated supply. As you will be using a regulated supply, I'd aim for about 300 volts out of the reg. supply so the value of R12 on the board can be quite low. Start with 300 ohms and see how it goes.
S.
I don't want to muddy the waters but, if after you've built your line stage and you find there is too much gain, Broskie offers a hack.
It is one he has included on some of his Aikido boards. If your octal doesn't have it you may still apply it with a little discreet hacking. See the link below and scroll down to nearly the end where it says: GAIN. There are a bunch of theoretical circuits but just a bit lower, just above the Al Di Meola piece, there are practical circuits for reducing gain in 6SN7 and 6DJ8 Aikidos.
https://tubecad.com/2020/08/blog0510.htm
It is one he has included on some of his Aikido boards. If your octal doesn't have it you may still apply it with a little discreet hacking. See the link below and scroll down to nearly the end where it says: GAIN. There are a bunch of theoretical circuits but just a bit lower, just above the Al Di Meola piece, there are practical circuits for reducing gain in 6SN7 and 6DJ8 Aikidos.
https://tubecad.com/2020/08/blog0510.htm