300B SE-OTL Build

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Ray P
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#1 300B SE-OTL Build

Post by Ray P »

I've been quietly working away at a build of Bruce Rozenblit's 300B SE-OTL amplifier (circuit published in 'Tubes and Circuits') for a couple of months now so thought it time to share progress.

As the name suggests, the amplifier uses 300B valves (times four) in an output transformerless design, producing around 1.5W.

Anyway, power supply is conventional CLCLC. I've built the power supply onto a tufnol sub-chassis so I don't have all of the mounting bolt heads visible on the finished amp chassis. Below are the main components laid out on the sub-chassis.

Ray

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Ray P
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#2

Post by Ray P »

Chassis top plate was done with front panel designer via here,

http://www.schaeffer-ag.de/index.php?id=97&L=1

Here's one of the chassis top plates starting to be populated. The power transformer is potted in a black shell and sits on top of the chassis. Power supply sub-chassis is held in place with the transformer bolt and industrial grade double-sided tape.

Ray

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Ray P
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#3

Post by Ray P »

Starting to hook up the UX4 sockets...

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#4

Post by Ray P »

and hooking up around the 12au7...

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#5

Post by Ray P »

and one channel, almost complete. Just need to add one of Andrew's 6.3V supplies for the 12au7 then double check everything.

Next step will be the back panel (due from Schaeffer in the next couple of days). Should be able to start applying power and measuring this time next week. I'll need to get some 300Bs soon!

Ray

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andrew Ivimey
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#6

Post by andrew Ivimey »

a load of old Shod!
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#7

Post by ed »

s'what blacksmiths do innits!
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nicoch
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#8

Post by nicoch »

HI

schematics ?
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Ray P
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#9

Post by Ray P »

nicoch wrote:HI

schematics ?
I don't own the intellectual property rights so am unable to publish the design on a public forum so you'll have to buy the book.

Ray

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#10

Post by Ray P »

andrew Ivimey wrote:a load of old Shod!
Finished that Paraglow yet?
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#11

Post by andrew Ivimey »

Ha ha, now that really is .... perhaps this winter break ;-)

onwards
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#12 Re:

Post by Thomas Turk »

Ray P wrote: Sun Nov 17, 2013 6:26 pm
nicoch wrote:HI

schematics ?
I don't own the intellectual property rights so am unable to publish the design on a public forum so you'll have to buy the book.

Ray

In the latest edition of Tubes and Circuits, the SE 300B OTL Project has been switched to the Pinnacle PP 300B OTL!! So will you sell me your edition book?
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