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Old 15th January 2013, 10:10 PM   #61
pso is offline pso  Spain
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Thanks for the good explanation, understood.
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Old 18th January 2013, 07:34 AM   #62
grufti is offline grufti  United States
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I have not been able to find a UX4 tube socket for the 300B tubes that looks like a fit for your driver PCB. Where did you find it?
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Old 18th January 2013, 08:12 AM   #63
tomchr is offline tomchr  United States
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I got mine on eBay. The ones I have look a lot like these: 300B Ceramic Socket. I think I just searched for 300B ceramic sockets.

"ux4 socket ceramic" returns this (among other things): Another ceramic socket.

Note the socket pins are intended to poke through the big hole in the board and then connect with short wires to the pads on the board.

~Tom
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Modulus-86: Composite amp achieving 0.00018 % THD. Damn Good 300B, Novar Spud, 21st Century Maida Reg., Filament Reg., etc.
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Last edited by tomchr; 18th January 2013 at 08:14 AM.
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Old 19th January 2013, 02:07 AM   #64
pso is offline pso  Spain
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Hi tomchr, I have a Tubelab SSE witch 6P3S-E (Good and cheap) but my PT (300-0-300) only produces 350 B+.

I have to buy a more powerful one and was thinking of buying the ClassicTone and your 300B-PSU and the Maida regulator boards, that would be an almost universal PSU.

That would allow me to run any tube, also tempts me your 300B but this tube is very expensive though 6N6P is very cheap, I have never heard a DHT so do not wait.

The SSE sounds great but I can not run more powerful tubes, my girlfriend gave me a pair of KT90's for Christmas and I was thinking about a 460-470 B+.

Your PSU+Maida can provide this voltage?
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Old 19th January 2013, 02:26 AM   #65
pso is offline pso  Spain
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Excuse my bad English, I meant Tubelab SSE with 6P3S-E.
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Old 19th January 2013, 10:22 PM   #66
tomchr is offline tomchr  United States
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Quote:
Originally Posted by pso View Post
Excuse my bad English
No need for an excuse. Your English is fine.

Quote:
Originally Posted by pso View Post
I have to buy a more powerful one and was thinking of buying the ClassicTone and your 300B-PSU and the Maida regulator boards, that would be an almost universal PSU.
Yep. I like the 0-330-380 secondary on the ClassicTone for that reason. It gives you many options for B+ voltages without dissipating ridiculous amounts of power in the 21st Century Maida Regulator. And if for some reason you want lower B+ voltages, you could always grab a different transformer and hook it to the 300B PSU board.

Quote:
Originally Posted by pso View Post
That would allow me to run any tube, also tempts me your 300B but this tube is very expensive though 6N6P is very cheap, I have never heard a DHT so do not wait.
You may want to take a look at this thread: One more 4P1L SE

The 4P1L is pretty inexpensive (<$5/each on eBay) and is supposed to be really good. You won't get as much power as you would with a 300B, but maybe with many in parallel... Or just get more efficient speakers.

Quote:
Originally Posted by pso View Post
I was thinking about a 460-470 B+.

Your PSU+Maida can provide this voltage?
I wouldn't run higher than 500 V RMS into the PSU board. That would result in about 650 V out (700 V at no load). So that's the limit there.

With the ClassicTone transformer, you'll get about 520 V out at nominal mains voltage. So roughly 490~550 V with +/-5 % mains variation (this is pretty tight, actually). The 21st Century Maida Regulator requires about 15 V across the regulator in order to regulate. So you're fine there.
But if the mains variation gets to +/-10 %, you'll run out of headroom. As far as I know, both the EU and the US operate at +/-5 % mains, so it should be alright, but I generally design for +/-10 % mains variation.

Another option is to lower the B+ voltage to 450 V. Then you can support +/-10 % mains variation with the ClassicTone transformer I specify.

~Tom
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Modulus-86: Composite amp achieving 0.00018 % THD. Damn Good 300B, Novar Spud, 21st Century Maida Reg., Filament Reg., etc.
Neurochrome : : Audio - http://www.neurochrome.com/audio - Engineering : : Done : : Right

Last edited by tomchr; 19th January 2013 at 10:25 PM.
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Old 20th January 2013, 03:37 AM   #67
pso is offline pso  Spain
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Look at the thread about the 4P1L, the circuit looks complicated to make a PTP, I like Tubelab designs and yours because they offer a PCB´s (easy and tidy).

Where I live mains voltage varies about 5%, then the PT recommended by you, what is the maximum B+ can by achieved?
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Old 20th January 2013, 08:11 AM   #68
tomchr is offline tomchr  United States
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I'd say the maximum B+ you can get with the ClassicTone 40-18069, my PSU board, and the 21st Century Maida Regulator for +/-5 % mains variation is roughly:

520 * 0.95 - 15 = 479 V.

That's assuming about 225 mA of steady-state load (like my 300B amp). If you push the transformer closer to the limit, I wouldn't count on more than 470~475 V.
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Modulus-86: Composite amp achieving 0.00018 % THD. Damn Good 300B, Novar Spud, 21st Century Maida Reg., Filament Reg., etc.
Neurochrome : : Audio - http://www.neurochrome.com/audio - Engineering : : Done : : Right
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Old 21st January 2013, 12:04 AM   #69
tomchr is offline tomchr  United States
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Default The plot thickens... :)

I promised pictures of how the ferrite bead mounts to the gate of Q1. See attached.

1) Gather materials: FQP3P50, machine screw (M3x8 or #4x3/8 is probably ideal), lock washer, nut, thermal goop, heat sink.
2) Using pliers, bend the leads on the FQP3P50 to a 90 degree angle such that the mounting hole and the pins line up with the respective holes on the board footprint. Apply a thin coat of thermal compound to the FQP3P50 and drape the ferrite bead onto the gate lead.
3) It requires a bit of skill and patience, but it is possible to get the FQP3P50 onto the heatsink and the combo aligned with the footprint on the board without losing the ferrite bead. Tighten the screw until the lock washer bites into the board. Cut and solder the leads.

Note: For the ultimate gory detail in the picture, right click on it and open it in a new tab.

~Tom
Attached Images
File Type: jpg 300B_PSU_R2p0_Q1.jpg (591.7 KB, 450 views)
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Modulus-86: Composite amp achieving 0.00018 % THD. Damn Good 300B, Novar Spud, 21st Century Maida Reg., Filament Reg., etc.
Neurochrome : : Audio - http://www.neurochrome.com/audio - Engineering : : Done : : Right
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Old 21st January 2013, 12:06 AM   #70
cotdt is offline cotdt  United States
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Hi Tom, Have you measured noise levels? I wonder if it is quiet enough for headphone use.
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