[BoilermakerFan]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif rodentmac, Do tell us more about the "space tube". Are these the same as the 12SN7GT? Have you read of a fav brand? RCA, GE, etc. Do you have any leads on pricing?(We wont require you to divulge your sources, lol)

The usual suspects have them for $20-$24 a tube, unless you want to buy a case of 100 NOS RCAs, then they are $17 each.

My 6GM8 tubes from John are Amperex Holland, but they aren't Bugle Boys...

 

[digger945]

I found these on a foreign ebay page. Look familar, he only has one matched pair.
Claims to be "red falcon" from West German stock.
EDIT: I finally got this page in english, the sale has ended. Sure are strange looking guts in these ones.

 

[digger945]

Boilermakerfan,
So your saying that these tubes can be had for about the same price as 6gm8's(when you can find them).

I didn't get to finish listening to the game this weekend, who won?

 

[BoilermakerFan]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif Boilermakerfan, So your saying that these tubes can be had for about the same price as 6gm8's(when you can find them). I didn't get to finish listening to the game this weekend, who won?

AES has them for $24. Not sure if anyone else has stock...

Those look like the RCA flat plates...

Iowa, 22-17.

 

[BoilermakerFan]

Comments on the 12SX7GT are on both pages:
http://www.head-fi.org/forums/f5/12s...mments-146617/

Scored a working Heathkit IT-17 tube tester on that auction site last night for $50 and it shipped from Louisville today so I'll have it tomorrow. No curve traces, just a fast Go-No Go tester for this huge box of tubes (and my old Magnavox console) I have so I can quickly sort duds. After that I can inventory my collection.

Which tubes do you think will sound better in the Aikido, 6GM8 or 12AU7A? I have 21 of the 12au7a tubes, but 3 are oddities with different getters. Most are RCA with round getters. I'll let you guys know how many are still good after tomorrow night if anyone is interested in a trade for other tubes like 6dj8 or 6cg7.

 

[rodentmacbeastie]

What needs to be done to convert this thing to 48V? I think that having a 24/48v power supply would let you use 12bh7 and 12sx7. Confirmed, the 12sx7 is meant to run at 28v. The only issue is the ss regs.

 

[BoilermakerFan]

Quote:

Originally Posted by rodentmacbeastie /img/forum/go_quote.gif What needs to be done to convert this thing to 48V? I think that having a 24/48v power supply would let you use 12bh7 and 12sx7. Confirmed, the 12sx7 is meant to run at 28v. The only issue is the ss regs.

Note, my reply is based on the REV. A manual...

For the 12BH7 R2, R4, R8, R11 change to 249ohm. C4 changes to a value range of 330uF to 2,200uF at 50V and all the other caps need to be rated at least to B+. So you could always move them up to a 200V or 300V rating across the board and cover yourself from the beginning. I think a nice quality selector switch or even a Darwin could be re-purposed to provide multi-voltage resistor values for each tube or PSU voltage.

A doubled VA 24VAC/6.3VAC dual secondaries toroid for series/parallel 24/48 connections with removable links could be used in conjunction with a LM317AHVT (to 57V) as the Vreg to allow only one B+ and one heater voltage through to the board(s). A more elaborate PSU is needed for 100V/200V/300V B+ supply.

 

[Coreyk78]

I apologize if my question here has already been answered somewhere else in the thread, I admit I haven't read even close to all of it yet.

Anyway, I'm very interested in building one of these primarily to use it as a tube preamp to drive my speaker amp. I was going to try building it using a cheap 24v dc switching power supply, like one for an lcd monitor or printer or something. But then I got the idea that it would be nice to build it with a phono section in the same chassis using the Very Simple Phono Stage design from RJM audio found here RJM Audio - The Very Simple Phono Stage and using a rotary selector switch to use the Aikido with several other sources.

The thing I don't know yet is how to get the voltages I need. Of course I would need +24v for the Aikido but then I also need +12v and -12v for the phono stage. I'm thinking there must be a way to get these using only 1 transformer but I don't know how. Would I be able to use a 24v series/12v parallel secondaries transformer?

I'm still pretty new at the DIY electronics game, but I learn quickly and am looking for some advice on what would be the most efficient way to power this stuff. I'm very early in planning how to make this work so I am open to any suggestions, I'm also going off the assumption that I only need a single +24v source to feed the Aikido, thats what I gathered from reading the original design article, so please correct me if I'm wrong. Thanks in advance!

 

[BoilermakerFan]

Quote:

Originally Posted by Coreyk78 /img/forum/go_quote.gif I apologize if my question here has already been answered somewhere else in the thread, I admit I haven't read even close to all of it yet. Anyway, I'm very interested in building one of these primarily to use it as a tube preamp to drive my speaker amp. I was going to try building it using a cheap 24v dc switching power supply, like one for an lcd monitor or printer or something. But then I got the idea that it would be nice to build it with a phono section in the same chassis using the Very Simple Phono Stage design from RJM audio found here RJM Audio - The Very Simple Phono Stage and using a rotary selector switch to use the Aikido with several other sources. The thing I don't know yet is how to get the voltages I need. Of course I would need +24v for the Aikido but then I also need +12v and -12v for the phono stage. I'm thinking there must be a way to get these using only 1 transformer but I don't know how. Would I be able to use a 24v series/12v parallel secondaries transformer? I'm still pretty new at the DIY electronics game, but I learn quickly and am looking for some advice on what would be the most efficient way to power this stuff. I'm very early in planning how to make this work so I am open to any suggestions, I'm also going off the assumption that I only need a single +24v source to feed the Aikido, thats what I gathered from reading the original design article, so please correct me if I'm wrong. Thanks in advance!

I would avoid a switching PSU, especially for a phono stage, just too much noise...

I am building Peter Daniel's modified version of the VSPS:
diyAudio Forums - AudioSector-chip amp kits, dacs, chassis - Page 75
diyAudio Forums - AudioSector-chip amp kits, dacs, chassis - Page 63

Peter's PSU is based on a 50VA Hammond 229D24 transformer which has dual 12Vac secondaries or 24Vac when wired in series. You can use a 50VA 12Vac dual secondaries toroid from AnTech and save some money to also buy a 100VA 24Vac dual secondaries toroid for the Aikido so you can wire the secondaries in parallel for 24Vac or series for 48Vac later. 50VA would be big enough for the Aikido, but I like the idea of having extra headroom in the transformer at 24Vac and keeping the higher current available at 48V though the LM317 v-reg is limited to 1.5A. Buy the HV version of the LM317 and your covered for both 24V and 48V Aikido builds in the future.

See Peter's PSU design for the phono stage and use John's PSU for the Aikido. Keep the two on separate PSUs to minimize the noise in the phono stage.

 

[Coreyk78]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif I would avoid a switching PSU, especially for a phono stage, just too much noise... I am building Peter Daniel's modified version of the VSPS: diyAudio Forums - AudioSector-chip amp kits, dacs, chassis - Page 75 diyAudio Forums - AudioSector-chip amp kits, dacs, chassis - Page 63 Peter's PSU is based on a 50VA Hammond 229D24 transformer which has dual 12Vac secondaries or 24Vac when wired in series. You can use a 50VA 12Vac dual secondaries toroid from AnTech and save some money to also buy a 100VA 24Vac dual secondaries toroid for the Aikido so you can wire the secondaries in parallel for 24Vac or series for 48Vac later. 50VA would be big enough for the Aikido, but I like the idea of having extra headroom in the transformer at 24Vac and keeping the higher current available at 48V though the LM317 v-reg is limited to 1.5A. Buy the HV version of the LM317 and your covered for both 24V and 48V Aikido builds in the future. See Peter's PSU design for the phono stage and use John's PSU for the Aikido. Keep the two on separate PSUs to minimize the noise in the phono stage.

Fantastic! thanks for the info and links, very helpful. I'm already familiar with Peter Daniel because I built my gainclone with one of his kits so I will definitely read up on his version of the VSPS.

The toroids sound like a great idea, and I was planning to order a couple transformers from them soon for the dual mono PA100 LM3886 based amp I am currently working on, so I could probably get the two small toroids in the same box and save the shipping on those.

Is the reason for using 48v to get a wider selection of tubes? Or is there some sonic improvement from running the higher voltage?

 

[digger945]

I really dig the idea of the multiple voltage PS. I talked to looser101 the other day and I think maybe I will try something besides the 6H30 on the recently aquired noval mono boards.

Glassware is all out of the Octal boards atm(you guys buy em all?), so maybe I will give the 5687 another looking over(gotta buy another pcb of course). The 5687 was my first choice, and there are some attractive tubes in the Cables, etc FS forum, maybe try the Sylvanias or something that Doctorsilantro has up FS.
Any suggestions for a noval tube to try? I am looking for a stong enough output to drive 25ohm Denons with aplomb.

I agree with Boiler on the PS issue Corey, I have never had any good results from trying to power one device with two different PS's.

 

[Coreyk78]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif You can use a 50VA 12Vac dual secondaries toroid from AnTech and save some money to also buy a 100VA 24Vac dual secondaries toroid for the Aikido so you can wire the secondaries in parallel for 24Vac or series for 48Vac later. 50VA would be big enough for the Aikido, but I like the idea of having extra headroom in the transformer at 24Vac and keeping the higher current available at 48V though the LM317 v-reg is limited to 1.5A. Buy the HV version of the LM317 and your covered for both 24V and 48V Aikido builds in the future. See Peter's PSU design for the phono stage and use John's PSU for the Aikido. Keep the two on separate PSUs to minimize the noise in the phono stage.

Question about using a 24vac dual secondaries xformer for the Aikido, that should be about 33.6vdc after rectification, is the LM317 going to be able to regulate that down close to 24v? That may be a stupid question, but I've never built a regulated PSU before, only unregulated.

 

[BoilermakerFan]

Quote:

Originally Posted by Coreyk78 /img/forum/go_quote.gif Question about using a 24vac dual secondaries xformer for the Aikido, that should be about 33.6vdc after rectification, is the LM317 going to be able to regulate that down close to 24v? That may be a stupid question, but I've never built a regulated PSU before, only unregulated.

Standard LM317 is good up to 37V, so it will be fine, you actually want a greater voltage delta to keep it running cooler and get better regulation. IIRC, you need at least 3V delta or it will run way too hot and eventually burn out. If you wanted too, you could use 22Vac secondaries just to bring the delta down a little, but the trafo John sent me is a 24Vac secondary. The LM338 will carry 5A, but is only rated to 32V, the LM350 will do 3A with a 33V max input voltage. Dropping to the 22Vac secondaries will sneak in the LM338/LM350 and allow double the current to pass to the amp.

 

[Coreyk78]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Standard LM317 is good up to 37V, so it will be fine, you actually want a greater voltage delta to keep it running cooler and get better regulation. IIRC, you need at least 3V delta or it will run way too hot and eventually burn out. If you wanted too, you could use 22Vac secondaries just to bring the delta down a little, but the trafo John sent me is a 24Vac secondary. The LM338 will carry 5A, but is only rated to 32V, the LM350 will do 3A with a 33V max input voltage. Dropping to the 22Vac secondaries will sneak in the LM338/LM350 and allow double the current to pass to the amp.

Thanks again, looking at what Antek has available a 22vac xformer may be the easier choice anyway since they don't have a part# listed for 24vac secondaries in 50 or 100VA sizes.

 

[BoilermakerFan]

Quote:

Originally Posted by Coreyk78 /img/forum/go_quote.gif Thanks again, looking at what Antek has available a 22vac xformer may be the easier choice anyway since they don't have a part# listed for 24vac secondaries in 50 or 100VA sizes.

I forgot about that. I need to order a 300VA 22Vac for my AudioSector Premium GC kits, a couple different 50VAs for phono stages/CD transports/DACs, and 4 100VAs for the MAXes and Aikido, but my Aikido one will either be 48V secondaries or 100V secondaries since I have a 24V trafo for it already. His shipping is $10 flat fee, so I plan to order a few HV toroids for other tube amp projects too.

A Broskie Aikido PH-1 will eventually be built with all 12AZ7A tubes for MM cartridges, but that's about a $350 investment and I need to build a second TT before that. Unfortunately, I've developed an addiction to phono stages. I have about 6 or 7 designs I want to build! The Daniel's modified VSPS is first and I have the parts. I want to build a Pass Pearl or derivative, the PH-1, and a couple others like the LP797.