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Old 30th December 2009, 05:52 PM   #1
JdJ is offline JdJ
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Thumbs up Throw it on the heap... SSE

Well with very little headache another SSE was born... I learned a few things along the way:

-One of the big ones was it's hard to cram one of these puppies in a 12.5x8x3 chassis. But I did it!

-Don't measure the resistance of the cathode resistors in circuit when warm - they will skew your readings leading you to think that your dissipation is MUCH lower than it actually is.

-I never figured out what was up with my SS rectifiers, but they were causing problems so they are gone... I used 512-ISL9R8120P2
8A 1200V STEALTH from Mouser - maybe the package is different from the FREDs - I never checked (read: DUMB!)

I thought I remembered someone saying the JJs EL34-L can handle higher dissipation than the standard EL34. The JJ chart says 25w max, but the tube database on Duncan Amps says 35?! I am running just under 26 with no plate glow.

Anyway - it sounds amazing!!

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Old 30th December 2009, 06:34 PM   #2
Glowbug is offline Glowbug  United States
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Looks great
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Jim J.
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Old 30th December 2009, 06:39 PM   #3
Brit01 is offline Brit01  United Kingdom
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Is that a big power supply oil cap squeezed in there?
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Old 30th December 2009, 06:42 PM   #4
JdJ is offline JdJ
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Thanks!

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Originally Posted by Brit01 View Post
Is that a big power supply oil cap squeezed in there?
Indeed - a 80uF 370VAC. I had to shoe-horn it in there as there was no real estate left on the top panel...
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Old 30th December 2009, 06:47 PM   #5
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Nice amp. I've been running winged C el34s at 29 W dissipation in triode for a long time w/o problem.
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Old 30th December 2009, 06:52 PM   #6
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Quote:
-Don't measure the resistance of the cathode resistors in circuit when warm - they will skew your readings leading you to think that your dissipation is MUCH lower than it actually is.
That shouldn't happen to a resistor. You were probably reading a bypass capacitor in parallel.
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Old 30th December 2009, 07:16 PM   #7
JdJ is offline JdJ
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Quote:
Originally Posted by Davec113 View Post
Nice amp. I've been running winged C el34s at 29 W dissipation in triode for a long time w/o problem.
Good to know - I went back to the TDSL and I must have mis-read it. All of the EL34 variations I looked at seem to have a max of 25 watts...

Quote:
Originally Posted by astouffer View Post
That shouldn't happen to a resistor. You were probably reading a bypass capacitor in parallel.
That's what I was thinking too. I haven't checked the schematic yet to see. I had read one of the myriad SSE posts where someone said they fluctuate with heat, but I can't find the post to re-read it so who knows, maybe I made it up... The long and short is I pulled one out while it was still warm and it was within 1% of where it was before.

-J
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Old 30th December 2009, 08:11 PM   #8
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Quote:
Originally Posted by JdJ View Post
-One of the big ones was it's hard to cram one of these puppies in a 12.5x8x3 chassis. But I did it!
Nice work. I felt like I was struggling to get it all in 9"x14". Still, I'm going to have to give you partial credit - the OPT are hanging off the edge!
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Old 30th December 2009, 10:29 PM   #9
JdJ is offline JdJ
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Originally Posted by Ty_Bower View Post
Nice work. I felt like I was struggling to get it all in 9"x14". Still, I'm going to have to give you partial credit - the OPT are hanging off the edge!

Ha! True - hence the "bash guard" to help balance it aesthetically.
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