I like the idea of the Muses but I need a pot for each channel. I found a mono alps pot in my pile so I'll just another one.
Have a look at the "Clone Note" ldr volume control, from Uriah Daley - if transparency is your aim...
Or a TVC if you're after a slightly more "analogue sound" to emulate something like Ed Shilling's "Truth" or the Bent Audio with Dave Slagle's AVCs, etc
You can easily change from 9 pin (Noval) to 8 pin (Octal) with a convertor socket if you leave room for the extra height.
Or a TVC if you're after a slightly more "analogue sound" to emulate something like Ed Shilling's "Truth" or the Bent Audio with Dave Slagle's AVCs, etc
You can easily change from 9 pin (Noval) to 8 pin (Octal) with a convertor socket if you leave room for the extra height.
Hi James. After looking at those options for volume control, I'm going to go with 2 mobo apps pots because of cost.
However I am intrigued with the idea of switching between 9 pin and octal tubes. Is that something that can be done without changing anything in the circuit?
However I am intrigued with the idea of switching between 9 pin and octal tubes. Is that something that can be done without changing anything in the circuit?
You need to be fairly specific about changing all the different tubes, not just between the 8 and 9 pin varieties - as you can see from the Aikido manual, there are different resistors required for different tube types - the sockets just allow you to use the wider range of tubes that are available. The change socket just plug into the existing sockets and then plug in the 'new' type tube to that.
I remember having to search all over the place for them on eBay but there's plenty of them available when you find them.
I see on your photo that you have both 9 pin and 8 pin board - I don't know this variety but pretty sure the designer will have kept the usual range of options.
One thing I'd suggest if the budget allows is to get a couple of the Obbligato caps for an optional output (add a simple heatshrink sleeve over their metal jacket for safety) - there's plenty options (and opinions) about the choice of capacitors - some cheaper nice Russian NOS too.
It looks like you've kept the power resistors well above the pcb surface - they 'char' the board after awhile if close to surface -
This, and the 'changer sockets' allow you optional tubes like 6SN7 input (8 pin) and say, 12BH7/ECC99 (9 pin) on a 9 pin Aikido board. That 'new' 6SN7 will require it's own specific resistors so keep this in mind (sometimes a higher resistance can just be reduced by adding parallel resistor - ie. solder on top).
I have a vague memory about using all the same heater supply voltage - there's a note about this in the manual.
I remember having to search all over the place for them on eBay but there's plenty of them available when you find them.
I see on your photo that you have both 9 pin and 8 pin board - I don't know this variety but pretty sure the designer will have kept the usual range of options.
One thing I'd suggest if the budget allows is to get a couple of the Obbligato caps for an optional output (add a simple heatshrink sleeve over their metal jacket for safety) - there's plenty options (and opinions) about the choice of capacitors - some cheaper nice Russian NOS too.
It looks like you've kept the power resistors well above the pcb surface - they 'char' the board after awhile if close to surface -
This, and the 'changer sockets' allow you optional tubes like 6SN7 input (8 pin) and say, 12BH7/ECC99 (9 pin) on a 9 pin Aikido board. That 'new' 6SN7 will require it's own specific resistors so keep this in mind (sometimes a higher resistance can just be reduced by adding parallel resistor - ie. solder on top).
I have a vague memory about using all the same heater supply voltage - there's a note about this in the manual.
Good thoughts James. I think I've come down with the "mightswell" if I'm going to build the amp I mightswell make it able to use all sorts of tubes.
That makes me tired. I'm going to build the amp with the ECC99 tubes and leave it at that.
That makes me tired. I'm going to build the amp with the ECC99 tubes and leave it at that.
You can always come back to it later if want/need to change something - it depends on the amount of gain you need, or if only using the back section, the buffer with the ECC99 tubes.
Just get it going and play for a bit - it's a bit of a surprise just how good this circuit sounds.
Just get it going and play for a bit - it's a bit of a surprise just how good this circuit sounds.
I reached out to John about the ECC99 tube not listed in the line amp section and he came right back with the resistors and such needed for that tube.
I was impressed with his quick response to my inquiry.
I was impressed with his quick response to my inquiry.
Could you post what he gave you? I'm curious since I used those tubes for output...and figured out my own math etc...You are planning on running heaters at 12V? Or? Honestly that's one of the major limiters with trying to keep options open for tube rolling...
Here you go.
Hi John, I bought a 1/3 completed kit from a guy who lost interest. I have 2 mono 9-pin PCBs Revision G and the Janus Shunt Regulator Rev. A The regulator is populated and the monos are not.
It came with 4 new ECC99 tubes and those don't show up in the manual (see picture) So Which one of the tube population sections should I use with these tubes.
Thanks much. Dennis.
Hi Dennis,
I would use 470 to 820 cathode resistors on the input tube and 300-ohm to 470 ohm cathode resistors on the output tube. Use 100k for R9 and 82.5k for R10. Use a B+ voltage between 240Vdc to 280Vdc.
-- John Broskie
Hi John, I bought a 1/3 completed kit from a guy who lost interest. I have 2 mono 9-pin PCBs Revision G and the Janus Shunt Regulator Rev. A The regulator is populated and the monos are not.
It came with 4 new ECC99 tubes and those don't show up in the manual (see picture) So Which one of the tube population sections should I use with these tubes.
Thanks much. Dennis.
Hi Dennis,
I would use 470 to 820 cathode resistors on the input tube and 300-ohm to 470 ohm cathode resistors on the output tube. Use 100k for R9 and 82.5k for R10. Use a B+ voltage between 240Vdc to 280Vdc.
-- John Broskie
Interesting... I run my tubes hotter than that... highest I've used with 6N6P is 240R... Usually I use 100R for the bottom cathode, and a jumper for the top one 🙂
I used toroids—only because I couldn't find pwr solutions that I liked for Iron core. Plus the stuffed depth/thickness of the Aikido board—with tubes exposed—required a 3.5" min height box and the whole package was going to be optimized by putting the transfos inside the chassis. You can use either type.
Thanks P. I never thought about size vs. room on the chassis. That actually might be an issue that could require a forth level.
I found a large transformer in my stash that has a 5v secondary and a 25v secondary. If I knock the 25v down to 12v can I use it for the filament supply? There is no CT just the 2 legs.
Any thoughts on using the 25v tranny knocked down to 12.6v for the filaments on both mono boards?
If you use just one diode to rectify the 25v winding, then less excess dc voltage for the regulator to dissipate.