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any reason to turn one of the chokes 90 degrees?

It usually helps cut down the noise, makes it harder for the hum & other crap from the transformer to get picked up by the choke and fed into the rest of the circuit.

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In addition to a regulator for the PS, a CCS plate load for the first stage will decrease distortion, a CCS cathode load for the second stage will also decrease distortion, and using a MOSFET instead

Hey hey, come on now, the main constraint of this exercise was OTL  give the man what he wants, even if it is worse.

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It usually helps cut down the noise, makes it harder for the hum & other crap from the transformer to get picked up by the choke and fed into the rest of the circuit.

This is basically what I was thinking, so the chokes are all rotated 90deg from the transformer.

I got the tube sockets mounted last night so I'm one step closer to wiring. Right now I'm going to go mark and maybe drill the holes for the two Lemo connectors, the IEC/fuse module and also the main power switch. I haven't decided if I'm going to have a separate power switch arrangement on the amp side yet, I'm leaning towards no.

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I haven't decided if I'm going to have a separate power switch arrangement on the amp side yet, I'm leaning towards no.

perhaps a mechanism where you can turn on the heaters independently of the B+ line? I'm going to do this in the amp I'm working on... sorta a manual soft-start.

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perhaps a mechanism where you can turn on the heaters independently of the B+ line? I'm going to do this in the amp I'm working on... sorta a manual soft-start.

Yeah, that's kind of what I was thinking as well. The problem being that given the time sensitive nature of this build the priority is to get a basic version working first and add more features later.
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Nights 4 and 5: the final PS chassis fab

So I got the tube sockets installed last night (I think it was last night...) and after painting a room today finally got back to it and did the panel layout and fabrication. I also tidied up the caps and chokes a bit and removed the labels. I'm hoping that this is the last time that I mount those particular bits. Overall I've very pleased with how things are coming along and hope to start the wiring tomorrow. The PS is really fairly simple as the eventual posting of the schematic will show and does use some nifty bits. My favorite, as already somewhat hinted at is the transformer. It is so unbelievably flexible it's crazy, here's a link to the data sheet. A few pictures and then it's just about sleepy time.

95521446.jpg

95521448.jpg

95521449.jpg

Oh, and two more picture to hint at what's coming in the amp section...

Imagine these

95521450.jpg

plus these

93258740.jpg

:kitty:

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Needed to get the additional power supply to use them with my SP. They actually transformed both my Darth Beyers, when I had them, and my K340s into different, and better, headphones. They were toastying up the amp though. Nate just reminded me that I killed mine somehow at the Tampa meet and need to get some more.

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6528s? Those and your 60lb power supply now have my interest.

I think it's a safe bet that you'll be a fan of the Menace given your main home amp. And I'll check with my supplier and see if he's got any more 6528s, if you're interested.

Woah, that power transformer is pretty sweet. Loving the look of your build, Nate.

I'm unfamiliar with 6528's.

The BFT is a friggen beast, to be sure and can probably be adapted to many a project given the available secondaries. And thanks for the kind words on the aesthetics. I'm not sure it'll win any beauty contests unless you're like me and drool over things like tanks and trains for the shear mass of them.

As far as the 6528s are concerned they are somewhat similar to the 6AS7/6080 family of tubes except that they have a 5A heater so they require a pretty non-standard power supply, as Vicki mentioned. I've actually got some pretty cool tubes to roll through this amp including 7236's and some uber rare Bendix tubes that allegedly have titanium in them.

I'm sure some of you at this point are drawing conclusions based on the tubes posted as well as other little details I've leaked. You're probably on the right track, I'll leave it at that for now.

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I think it's a safe bet that you'll be a fan of the Menace given your main home amp. And I'll check with my supplier and see if he's got any more 6528s, if you're interested.

CanJam is only 20 days away. You'll now not be forgiven if the Menace isn't in attendance. Re tubes, I'm 100% interested, and to be specific, I'd love to snag four (two for back-up) if at all possible.

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95521448.jpg

Why do you have 2 four pin powerconnectors at the back ?

what are you using to reinforce the chassis ?

:popcorn:

Do such physically large caps take very long to burn-in / stabilise ?

Once it's done I'd be interested to know what it weighs :)

I'm looking forward to the schematics for this :)

I can't quite understand the role the tubes are going to play. Transformer takes in mains voltage and through inductance generates other voltages/ampages, the chokes I can understand clean up the dc and I'm guessing the capacitors play a role in that as well. What is it the tubes do ? :scratchinghead:

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CanJam is only 20 days away. You'll now not be forgiven if the Menace isn't in attendance.

You know, the first time I read that I saw now instead of not and thought, "Awww, isn't that nice of Vicki to say." Now I'm more like :o.

Re tubes, I'm 100% interested, and to be specific, I'd love to snag four (two for back-up) if at all possible.

I'll PM as soon as I have info.

Why do you have 2 four pin powerconnectors at the back ?

There are two heater supplies for the amp (input/output) so that's one set of 4 and there are left and right HV supplies so there are the other 4.

what are you using to reinforce the chassis ?
What it feels like it needs is a stiff bottom plate to increase torsional rigidity. I've got some 3/4" oak and maple that is high on my list to use. >:D

Do such physically large caps take very long to burn-in / stabilise ?
No clue but I also don't care since I'll just be burning it in through use.

Once it's done I'd be interested to know what it weighs :)

Somewhere in the 50 to 60lb range. The trafo is 15, the big choke 21, the chassis another 5 then you've got the caps, 2 other chokes and everything else.

i'd guess they are tube rectifiers, and there's going to be 1 PSU per channel

Justin is mostly correct, they are rectifiers but they are run in parallel rather than separately. The supplies don't separate until after the large primary choke.
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You know, the first time I read that I saw now instead of not and thought, "Awww, isn't that nice of Vicki to say." Now I'm more like :o.

I have complete confidence in you and eagerly await a CanJam debut. Btw, I was switching back and forth last night between your Senn cable and my all-time fav Equinox, and it holds its own without question. Really need to hear it with the 650s now. It's quite good.

I'll PM as soon as I have info.

gracias

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so, you have a giant trafo capable of 770 VCT and then tubes with 300v and 400v max plate voltage? where's all that extra voltage going? Assuming you're loosing 50v or so per rectifier...

The way I understand it each rectifier is fed 385V and then the various other stages drop the B+ down to ~300V at the output. While I didn't design the power supply or the amp for that matter I have complete confidence in the guy that did. The B+ requirements are 300V/.4A which made traditional, single rectifier designs impossible and made trafo selection a matter of "can this be made to work" rather than "this one works best".
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The way I understand it each rectifier is fed 385V and then the various other stages drop the B+ down to ~300V at the output. While I didn't design the power supply or the amp for that matter I have complete confidence in the guy that did. The B+ requirements are 300V/.4A which made traditional, single rectifier designs impossible and made trafo selection a matter of "can this be made to work" rather than "this one works best".

seems like a perfect situation for tv damper diodes... Would you mind sharing the choke part number?

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