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PostPosted: 20 Jul 2010, 19:21 
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Actually, I draw all my load lines in either Keynote (Apple) or Powerpoint (Microsoft) depending on whether I'm at work or at home. I just plop an image of the curves I want on a page and draw lines where I want them. The schematics are actually drawn manually in Appleworks. I know it's an old program but I like it because I can add anything I want, anywhere I want. Almost like a real sheet of paper.

Now for the good stuff. I've finished a power supply design. My decision to go with a lower voltage and higher current in the 807s almost tanked the power supply design effort. After looking at all the Edcor power transformers, I could only find one that truly works for this amp design; and it will be run right at it's design limits. I've attached my PS design worksheet and final schematic. I settled on the Edcor XPRW002 which has a primary that will be run very close to it's design limit. However there is a low voltage secondary that's 48VA which we won't use so we should be able to draw the few extra mA off the main primary that will be required at full load. I played with using the XPWR132 which would have more margin but doesn't have the 6.3v current available for all three tubes so another filament transformer would be required. It's also a lot more expensive then the XPWR002.

The final design should have a ripple of about 0.014% at full load. This is right in the middle of the 0.005% to 0.05% range suggested by Herbert Reich in section 14-3 of "Theory and Application of Electron Tubes" for audio amplifiers. If greater ripple reduction is required, the final 10Ω resistor should be upped to 20Ω and the final capacitor increased to 200µf. The other two capacitors shouldn't be increased if possible. Increasing the 40µf cap would violate the max limit for the 5U4 and I'm afraid that increasing the first 100µf cap will cause in rush problems for the 5U4. There is no stand-by switch in this design. The 807 and 6SN7 both have unipotential cathodes so stripping won't be a problem. Just throw the main power switch and let every thing warm up together. This is especially important for the 5U4 to avoid hot switching transients.

As before, here is my first put at a power supply design. Take a look at the overall design, poke holes in it, recommend any changes you think would improve the design, etc. This is just the first cut at a workable design so comments, suggestions, changes, etc. are more then welcome.

Let me know what you think.


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PostPosted: 20 Jul 2010, 20:16 
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Location: Australia
Matt

I have taken copies of the PS and the amp schematic. Thanks a bunch. This will be a truely international amp. Designed in America and built in Australia. And original.

I am well into the current amp I am working on so should get a chance to start on the ATS25/807 soon. I will order the power tranny today. The rest I have. Ceramic sockets and anode caps are on their way.

I took a look at your site. Very good. We have similar tastes in amp layout. I like the wood look too.

Feel free to e-mail me and stay in touch. Did you see the 6AS7 amp I am building?

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PostPosted: 31 Jul 2010, 05:06 
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Hi.
I like this SE-807 (also testing these small modifications)
I have a pair of J-6123, project SE KT88, I only have a pair of Chinese KT88/98 of dubious matching

807s I have good quality, including Philips PE/06 40E and 40N. These James supported the current of this circuit,
with the primary connection 5 K and the secondary 8 Ohms boxes to 16 ohm tap of the OPT?

Thanks
Fernan

P.S. Ecuses by the translator Inglish.


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PostPosted: 31 Jul 2010, 08:09 
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Fernan, do you have some images and a schematic of the 807 amp?

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PostPosted: 31 Jul 2010, 09:50 
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HI mwhouston
YES, it is the same SE AT25 / 807 two stage tube amp, posted by Suncalc
Thanks


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PostPosted: 31 Jul 2010, 17:59 
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From what I know this has not been built yet. Have I got this right?

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PostPosted: 01 Aug 2010, 04:06 
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mwhouston wrote:
Matt

I have taken copies of the PS and the amp schematic. Thanks a bunch. This will be a truely international amp. Designed in America and built in Australia. And original.

I am well into the current amp I am working on so should get a chance to start on the ATS25/807 soon. I will order the power tranny today. The rest I have. Ceramic sockets and anode caps are on their way.

I took a look at your site. Very good. We have similar tastes in amp layout. I like the wood look too.

Feel free to e-mail me and stay in touch. Did you see the 6AS7 amp I am building?

To quote myself. I have more of the parts now for the ATS-25 amp. Edcor is slow to get back to me about the power tranni etc. so still waiting a shipment notice from them. My 6AS7 is well finished and is off the planet for sound and bass extension. I'm wondering if the 6AS7 amp can be bested. The amp does more than rock, it rolls.

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PostPosted: 01 Aug 2010, 05:07 
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mwhouston wrote:
From what I know this has not been built yet. Have I got this right?

Mwhouston

It seems to me that I do not understand your question.
I want to say I need rights or permission to mount this nice design Matt?

Greetings
Fernan


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PostPosted: 01 Aug 2010, 06:00 
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Fernan wrote:
mwhouston wrote:
From what I know this has not been built yet. Have I got this right?

Mwhouston

It seems to me that I do not understand your question.
I want to say I need rights or permission to mount this nice design Matt?

I think I you have missed my question. Not as in legal rights but right as in correct.

So let me ask again: "From what I know this has not been built yet. Have I got this correct?"

As far as I know, Suncalc put the design out there for anyone to build. I'm sure there is no copyright on his design for personal use.

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PostPosted: 01 Aug 2010, 06:26 
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Hi
No, I have not made project.

Advised EDCOR 25W, EDCOR 10 and 15W are not sufficient.

I am James 6123, 20W 5K primary. My question is if these can be attached to the tap 16 ohm 8-ohm speakers, resulting in the 2K5 primary is suficient.

Thanks, all the best
Fernan

P.S. The reason is that, for SE-KT88 I have Chinas KT88/98 of dubious matched, 807s I have quality, including Philips PE/06 40E and 40N, I like this tubes and your project.


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