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Old 13th February 2013, 03:52 PM   #21
rknize is offline rknize  United States
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That's a bit on the high side for sure. I can certainly see why the already-hot Allied was unhappy.

My home is around 120VAC this time of year. It drops down to 110 or lower in the summer. George also has very poor waveform at his home after lightening took out the old school transformer outside of his house (if I remember the story). With all of the rectified power supplies that live on our power system these days, they put a nasty notch in the wave form where the diodes cut-off. This creates harmonics that can exacerbate the audible buzz from a power transformer.
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Old 13th February 2013, 05:19 PM   #22
rmyauck is offline rmyauck  Canada
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Mine varies from 115-117 to 127 also! I saw somewhere on a form where a fellow made pre ps transformer filter out of IN4007 diodes and 3,300 uF caps . If I remember right they were only 16V.

I guess 16V is okay as your after DC which will be very low. He said it got rid the DC and so made the trans. run a lot cooler. I don't remember about noise being a problem in that case though.

Randy
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Old 13th February 2013, 06:08 PM   #23
kkcinc is offline kkcinc  United States
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Line voltage is 123 today. I did a quick checkout and came out with 440 B+ right on the nose. I measured right where the very last cap screws to the board. Plus side of cathode resistor to ground measured 41. I used two 6550's, one 5ar4, one 12at7. Solid state diodes are not in use. I used this very same board for two years with another transformer. It ran hot, but that transformer is notorious. The old one also made a hum, but it sounded like a normal hum that many things make when turned on. I could hold my hand on that one for 5-6 seconds after rocking out for a couple of hours. I ran the new one for two hours this morning and could only hold my hand on it for 3 seconds. I would've actually measured the temp if I thought of it.

Last edited by kkcinc; 13th February 2013 at 06:10 PM. Reason: spelling
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Old 13th February 2013, 08:12 PM   #24
rknize is offline rknize  United States
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OK, so you are running ~73mA per tube. Total B+ load should be something like 160-165mA. Seems like you are well within spec on the B+ side of things.

Solid state diodes are not in use...but are they installed? They are present to the transformer even if the switch is not thrown to make them the source of rectification. What diodes are you using?

Aside from that...yeah it seems like there is something amiss with the transformer.
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Old 15th February 2013, 12:21 PM   #25
kkcinc is offline kkcinc  United States
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Well I ran it for about two hours with el 34's and 5ar4. Same 12at7. It was cool for a while then just warm by the time I shut it off. What a bummer because I think it just can't handle what it is rated for. I bought it because it was 380-0-380 as opposed to the 375-0-375 of the Allied. Also the alleged current rating is 200ma versus Allied's 175ma. So disappointed because I wanted the extra oomph and current for solid state operation. Also this one was the cheapest one they offer that will work in the sse. I think it is cheaper because it is cheaper if you know what I mean. Also I think this one is partially, if not totally, outsourced. I say that because it is the exact same dimensions as the Allied and the exact same holes. It made it convenient, but I found it curious.
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Old 15th February 2013, 05:34 PM   #26
kkcinc is offline kkcinc  United States
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Actually the Allied is rated at 150ma. I think I was pushing 160 for two years with no problem.
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Old 15th February 2013, 05:44 PM   #27
rmyauck is offline rmyauck  Canada
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Maybe you can run the amp like mono blocks with one Trans./CH. Besides better separation, you may gain lots of headroom in the PS then too. You would have to maybe perfboard the second PS caps etc. I'd try it with the 2 different Trans. first.

Maybe a crazy thought!

If you run it with one output tube out is it quieter and run cooler?

Randy

Last edited by rmyauck; 15th February 2013 at 05:51 PM.
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Old 15th February 2013, 05:51 PM   #28
kkcinc is offline kkcinc  United States
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Quote:
Originally Posted by kkcinc View Post
Well I ran it for about two hours with el 34's and 5ar4. Same 12at7. It was cool for a while then just warm by the time I shut it off. What a bummer because I think it just can't handle what it is rated for. I bought it because it was 380-0-380 as opposed to the 375-0-375 of the Allied. Also the alleged current rating is 200ma versus Allied's 175ma. So disappointed because I wanted the extra oomph and current for solid state operation. Also this one was the cheapest one they offer that will work in the sse. I think it is cheaper because it is cheaper if you know what I mean. Also I think this one is partially, if not totally, outsourced. I say that because it is the exact same dimensions as the Allied and the exact same holes. It made it convenient, but I found it curious.
Quote:
Originally Posted by rmyauck View Post
Maybe you can run the amp like mono blocks with one Trans./CH. Besides better separation, you may gain lots of headroom in the PS then too. You would have to perfboard the second PS caps etc. I'd try it with the 2 different PS first.

Maybe a crazy thought!

If you run it with one output tube out is it quieter and run cooler?

I do have two boards. Not a bad idea, although I'd love to figure a way to use all the power of both output tubes going to one channel. I'm a beginner, but I believe I have heard it called parallel operation. Or, I can try what you said. New chassis required.

Randy
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Old 15th February 2013, 06:02 PM   #29
rmyauck is offline rmyauck  Canada
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Are you using a choke and if so what is it?

Randy
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Old 15th February 2013, 06:03 PM   #30
kkcinc is offline kkcinc  United States
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God knows what I just did there.
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