[BoilermakerFan]

It's not that you can't power multiple devices off one transformer; it's the issue that you +/-12-15V for the VSPS and 0-24 or 0-48 for the Aikido. If you wanted to limit yourself to 24V on the Aikido you have a much more limited tube selection, but you could order a 100-200VA toroid with dual 12Vac secondaries and pull the 24Vac for the Aikdo from a series connection and the 12Vac for the VSPS, but I would definitely use a filtered IEC socket and fuse each PSU separately, on both legs. You'll still have the chance for more noise, you might be splitting hairs too if your power is good and your ground is good.

The 6GM8 cannot be run at 48V.

Other novals include the 12au7a (150V), 6922(48-170V), 6DJ8 (48-170V), 6h30(48-200V), 6n6p(100-200V), 6n1p(200-250V), 6cg7(200V), and 12BH7(48-250V). I would start with the 6DJ8/6922 and 12BH7 tubes at 48V first... There are a lot of nice options for sourcing new 6922 tubes too, so that makes them easier to find and you can get crazy and buy matched cryo'd sets for less than some of the 6GM8 or 6h30pi tubes...

There are actually a lot of other noval options, but their gains are just to high, most between 50-100, which could be great for 1V CDPs, or MCs run through 40dB phono stages if the noise is kept in check, but probably not good for most other applications.

 

[rodentmacbeastie]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif It's not that you can't power multiple devices off one transformer; it's the issue that you +/-12-15V for the VSPS and 0-24 or 0-48 for the Aikido. If you wanted to limit yourself to 24V on the Aikido you have a much more limited tube selection, but you could order a 100-200VA toroid with dual 12Vac secondaries and pull the 24Vac for the Aikdo from a series connection and the 12Vac for the VSPS, but I would definitely use a filtered IEC socket and fuse each PSU separately, on both legs. .

I am interested in a 48V Aikido, but I think I am going to stick with the 24V and maybe try a 12SX7GT in there. I got my boards yesterday and the 6N27P tubes form that dude on Ebay. Now I have to order parts for the board.

I have all my resistors picked and the cap are up in the air at the moment. Anyone have suggestions for what caps to use?

 

[BoilermakerFan]

Quote:

Originally Posted by rodentmacbeastie /img/forum/go_quote.gif I am interested in a 48V Aikido, but I think I am going to stick with the 24V and maybe try a 12SX7GT in there. I got my boards yesterday and the 6N27P tubes form that dude on Ebay. Now I have to order parts for the board. I have all my resistors picked and the cap are up in the air at the moment. Anyone have suggestions for what caps to use?

Just use the LM317HV and a 22Vac dual secondaries transformer and you can easily step it up to 48V later. Just realize you will have to change out 6-10 resistors. I would go a step further and order higher voltage caps for the boards so I could build a 250V unit later an only need to swap resistors again.

Here's the HV 317:
LM317AHVT

And John loves the RTI caps:
PS-1 Solid-State Regulator Kit

He included the RTIs with Panasonic FMs in my kit. Manaox2 posted my BOM message a few pages back. I would only change the small mica cap to a Wima red box cap if I were ordering my own parts... I'll be adding big Coke can sized oil motor run caps for C4 when I build mine mainly for fun to try it... I forget the value of the caps at the moment.

 

[digger945]

rodent, are you building your 12SX7 as a linestage or hp amp?

 

[rhester]

What kin dof power supplies are you'll using to power the Akidio? Anybody used the sigma22 from amb?

 

[digger945]

This is what I am using atm, don't know exactly what it is:
Top of PS
Bottom of PS
xfmr
It is set to exactly 24V. It will go higher, but doesn't sound as good.
It uses a 338 reg, and is adjustable with a bournes pot.

I started with a medical 24V 2A supply, it doesn't sound bad at all, I just don't use it anymore.
I use one PS and tie the B+ and heaters together on the board(heaters in series), as the 24V aikido board is designed to be run this way(if you like, and only have one PS).

 

[BoilermakerFan]

The PSU is pretty open, Peeps have used S22, STEPs, TREAD, etc. The PSU just needs to be a good quality linear regulated supply. The Aikido architecture cuts the noise in half, but starting with a good, clean supply improves the sound of any device exponentially.

John offers a low cost PSU kit. Peter Daniel has a great one for his AudioSector gainclone kits that many of us have used for other applications too. You'll have to email Peter through his AudioSector web site to get the costs for just the PSU or PSU kits...

 

[digger945]

The H-PS-1 is $24usd at the glassware yahoo store. This is a beautiful PS and you only need a trafo to go with it.

Looks like the PS-1 kit has the regs for both high and low voltage(you need two trafos or one trafo with both high and low volt secondary). This is a nice PS as well. It is $74usd complete except transformer.

Any last minute suggestions before I pull the trigger on a 5687+PS-1 kit? (I am re-reading you guys posts now)
I guess I will wait for octal pcb's and shop in the mean time for 12SX7 tubes.
Every day I read another article about the 12SX7 beating the snot out of the best of 6SN7's.

 

[manaox2]

Quote:

Originally Posted by rhester /img/forum/go_quote.gif What kin dof power supplies are you'll using to power the Akidio? Anybody used the sigma22 from amb?

I have been strongly considering it because it is designed with the negative rail and for dual 25V inputs matching the transformer I have for a balanced 4 channel amplifier.

 

[digger945]

Hey, howz that project coming along?
You gonna have some time off the end of next week?

 

[manaox2]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif Hey, howz that project coming along? You gonna have some time off the end of next week?

YHPM

 

[rodentmacbeastie]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif rodent, are you building your 12SX7 as a linestage or hp amp?

I am building a 24V first, but I was thinking that since a 12SX7 was designed to run at 28v it would sound ok at 24v. If it sounded as good or better than the 6GM8 then why not try it at 48v. If I can use a LM317AHVT (x4) for the buffer and change a few resistors to accomodate a 12BH7 or a 12SX7 to make it sound better, why wouldn't I. Can't I use the LM317AHVT in the 24V build with the same heat sink an all and then when I go 48V I can change the resistors, adjust the voltage on the LM317AHVT, and it is 48V Aikido, right?

 

[rodentmacbeastie]

Quote:

Originally Posted by manaox2 /img/forum/go_quote.gif I have been strongly considering it because it is designed with the negative rail and for dual 25V inputs matching the transformer I have for a balanced 4 channel amplifier.

I am building a balanced Aikido(2-24v boards) as well and was wondering about your intended use of the negative rail?

 

[digger945]

rodent,
The data sheet for the 317HV shows that it has a voltage differential of some 60 volts. It is rated at 57 volts. I got to thinking about this and I really don't see why it wouldn't work just fine. Matter of fact, I am pretty sure the 317T would work also. If we put the 317 in the circuit with a 48V B+ then wouldn't just one 317 only "see" half of the voltage anyway?

On the schematic, the two regs(2540 shown, it was the only one I could find) in series from B+ to ground will pretty much split the voltage in half(I read 13.2 volts @ 24V B+ on mine).
When I though about this further, I think as long as your device(317/337/2540, etc.) can handle the voltage and current from biasing, and your heatsink can dissapate whatever heat, you should be just fine.

FWIW, the DN2540N5 that I have in mine now is rated up to 400V, and is able to dissapate 15W(TO-220 package only). They are $1.60 each at Mouser.
I will see if I can find the correct circuit with the 317's in it and redraw it with your 48V B+. I don't know about you guys, but it really helps me to look at the circuit on screen or printout.

As for the 12SX7, if it needs 28V on the plate, I don't see why you couldn't build the circuit with 48V B+ and maybe crank it up later to see what the difference in SQ is. I bet it would work good with 24V on the plate.

 

[rodentmacbeastie]

I am looking at some crazy ideas for cooling anyway, so the extra heat will not be a problem. My Box-o-Goodies is going to be one vintage looking stereo cabinet abou 24" wide, 16" high and 12" deep. Inside that box I will have a HTPC with ESI Juli@ outputing I2S to a Buffalo DAC with NP D1 I/V stage. The DAC will receive DSD as well from a Denon spinner. The Aikido is next to a Firstwatt F1. I figure the F1 will handle a full ranger like a good HP amp handles cans, I got used to control and less distortion. This will be cooled by two liquid cooling systems. One will cool the air in the whole box(sealed to control humidity) by mounting a rad core inside as well. The second will directly cool the F1 and now maybe the Aikido buffers. I bought some Peltier thermoelectric plates to play with. When I build my house I am going to integrate these elements into my hot water heater and aircon systems. I am thinking that, since I have moving water on the land I will build a small generator from a car alternator(generator). The 12V DC is great for the lights, fans, Peltier plates, etc. I was thinking about running the DAC, Aikido, PC, and F1 off DC-DC power supplies. The only appliances that need AC are the TV and fridge. If I build a HT I would like to build a projector using LEDs as a light source and run it off DC as well. I guess I could wire four 12V batteries with relays to cut charge lines when the power is on. I could use one battery for the DAC and PC, three batteries in series for the 30V D1 rails, and all four wired in series for the 48V. I am sure the F1 would fit in there somewhere. If you have any other ideas or simple DC-DC 12V power supplies to get me the 30V+/- for the D1 and the 48V B+ for the Aikido. I am not so learned yet, this is all just ideas.

The benefits of a 12V DC house:
- less electrical stress on us.
- less noise in the power.
- less heat generated by conversion between AC and DC.
- free power and the infrastucture would cost half.
- "the man" has to mind his own business.
- less issues with Thai monsoons making things go boom.
- less expensive power capacitors.

I would use an invertor to get my 220V AC if it is necessary, but I am afraid that it will introduce lots of noise. I guess I could convert the power to 220V and use dual 55V transformer to convert the power from 220V to balanced 110V. This way I could use it easily in Canada and buy the big transformer in Thailand to act as a 220V/110V converter. This should also remove any noise introduced by the inverter.

On a different note... Is there not a way to use two of these boards in a balanced push/pull set-up and remove all of the output caps?