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Grainger49
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« on: January 01, 2012, 02:15:51 PM » |
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I'm going to make some changes to my Paramours. They are one of the last four pair Doc put on sale just before the Paramour II came out. So mine are very late production.
Today I got a little aggravated because I hadn't adjusted the hum pot since changing tubes. The belly of the beast is filled with stuff making it dangerous to adjust anything. Today I put the hum pots on the top plate. I wish I had heard of this before assembly, there is the perfect place on the top plate in front of the power transformer and back from the input jack.
I'm happy with this, I got one amp to 1mV hum, the other to 1.8mV. The sub woofer's plate amp has some physical vibration that hums louder than the system now.
More later, less sooner.
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« Last Edit: February 17, 2012, 07:10:46 AM by Grainger49 »
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Grainger Morrison,
Mozzie quote: Sacred cows make the best hamburgers!
Remember, YOU are the only one who needs to be happy with the sound of your system.
Eros (Mods Have Begun!)/FP-2/Paramour 1/upgrades to all - PS Audio Regenerator, Triangle Zerius Speakers, BA Sub
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Paul Joppa
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« Reply #1 on: January 01, 2012, 08:48:10 PM » |
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Excellent! And now you know why the hum pot is on top of the chassis in the Paramour II. (You've probably already figured out why there's an IEC socket... :^)
Before the Paramour, and before we got into parafeed, I made a 2A3/300B amp based on the original SEX monoblocks. Must have been around 1997, documented in VALVE under the title "S.E.X. and the Single 300B" - Grainger, I'm sure you remember Helen Gurley Brown! It was the same chassis plate that was used for the first Paramour, and that's exactly the same place that I put the hum pot, for exactly the same reason.
It ran a little hot, about 18 watts, which is why we had a custom power transformer made for the Paramour. I had a bunch of cheap Shuguang biplate 2A3s; back then they had a habit of crapping out before they hit 1000 hours irrespective of the plate dissipation, so I thought "smoke 'em if you got 'em" ... that amp served me well for at least a decade. :^)
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Paul Joppa
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Grainger49
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« Reply #2 on: January 02, 2012, 05:29:08 AM » |
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Ha, ha! Paula asked, "What?" when she heard me laughing over here. I remember Sex And The Single Girl, but never read it. Maybe I should have? I needed a lot of pointers in those days. I never got them either.
The lack of an IEC socket hasn't bothered me that much. I feed the power cord into the base then flip and work on it. I haven't found an IEC power cord long enough to reach neatly from my right amp to my P300. If I put on an IEC it will be on the back of the base then I will mount the toroidal balun to the base and run stranded all the way to the power input terminal strip. The solid wire broke from the balun to the terminal strip on both amps when I worked on them yesterday.
I have a short list of "upgrades" for these and will update the thread as I go. Soon I will put a picture in of yesterday's work.
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« Last Edit: February 17, 2012, 05:42:54 AM by Grainger49 »
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Grainger Morrison,
Mozzie quote: Sacred cows make the best hamburgers!
Remember, YOU are the only one who needs to be happy with the sound of your system.
Eros (Mods Have Begun!)/FP-2/Paramour 1/upgrades to all - PS Audio Regenerator, Triangle Zerius Speakers, BA Sub
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Grainger49
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« Reply #3 on: February 17, 2012, 05:46:54 AM » |
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PJ, elsewhere in a thread started by xcortes, has suggested a shorting switch to short the primary (after the parafeed cap) of the output transformer. The reasoning is that the startup bleeds some DC through the parafeed cap and magnetizes the primary of the transformer. It takes half to an hour to clear it out and the amp to sound its best.
I mistakenly bought a pair of DPDT toggle switches with a spring return to center off from one position. I can use these! Thank goodness I'm a pack rat and didn't throw them out. I will turn on the amp, hold the switch shorting the primary for 30-60 seconds then turn on the other amp.
Edit: I must have discarded the switches or lost them. I used a SPST switch on each amp. There was no smoke but I have to turn the switches off. I won't forget because I'm going to be kneeling in front of the amps to turn them on anyway.
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« Last Edit: February 17, 2012, 01:56:17 PM by Grainger49 »
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Grainger Morrison,
Mozzie quote: Sacred cows make the best hamburgers!
Remember, YOU are the only one who needs to be happy with the sound of your system.
Eros (Mods Have Begun!)/FP-2/Paramour 1/upgrades to all - PS Audio Regenerator, Triangle Zerius Speakers, BA Sub
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Grainger49
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« Reply #4 on: May 12, 2012, 09:44:34 AM » |
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So when I changed the drivers tubes to 76s I got help from PJ with setting them up. I got the plates to 250V and since he said +/-50V from 200V, the target, I left them there. Then working with Paully on his next project I found I am running them pretty hot. Maybe that is why I eat up driver tubes and not output tubes.
A little calculating and a quick search through my resistor collection, I paralleled a resistor with each cathode resistor. Now the combination measures 1988 ohms, each, and the voltage is 197V. Much closer to target!
Next a bypass of the cathode cap or a replacement for it. (probably a bypass)
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Logged
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Grainger Morrison,
Mozzie quote: Sacred cows make the best hamburgers!
Remember, YOU are the only one who needs to be happy with the sound of your system.
Eros (Mods Have Begun!)/FP-2/Paramour 1/upgrades to all - PS Audio Regenerator, Triangle Zerius Speakers, BA Sub
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