Paramour 1 - further mods

[patrickamory]

So of course now that you guys have helped me get my Paramour 1s back up and running, I'm thinking about what else I can do. I seem to get the most noise around the inputs when they are touched or brushed - possibly my interconnects are slightly loose on the jacks? Generally I'm getting a modest degree of hum or noise, but it's very difficult to adjust the hum pots in my current rack while connected - the 2A3s bump up against the shelf above.

And I found these additional instructions that PJ gave in 2011 to someone who had just built a surviving unbuilt Paramour 1 kit. I don't think I have this connection in place:

Also, make sure the 12AT7 heater pin 9 is grounded to the chassis at T14. In the original build the heater power floated; I don't think this grounding made it into the manual.

I think I MIGHT have the following connections right - could you guys please confirm from the attached photo?

And while I am reminiscing about this amp, make sure the 499 ohm grid stopper at the 2A3 pin 3 goes to T17, and so does the 270K grid resistor and the 0.1uF coupling cap. Only the stopper goes to tube pin 3, nothing else.

This sentence is slightly confusing - should the 270K grid resistor go to T17 rather than 2A3?

Any other changes you recommend I make while I'm in there? I don't think I'm going to go to the trouble of trying to swap out to the tabbed power transformer.

Thanks again!
Patrick

Quote from: porcupunctis on November 13, 2011, 11:20:38 am
... It told me the hum was 60Hz and it's RMS was 5-6 mV.  This is very close to what I had measured with the Fluke....

If it's actually 60Hz then the hum pot will adjust it out. Also if it's 60Hz, consider the possibility of nearby transformers which might have a magnetic hum field around them.

Also, make sure the 12AT7 heater pin 9 is grounded to the chassis at T14. In the original build the heater power floated; I don't think this grounding made it into the manual. And while I am reminiscing about this amp, make sure the 499 ohm grid stopper at the 2A3 pin 3 goes to T17, and so does the 270K grid resistor and the 0.1uF coupling cap. Only the stopper goes to tube pin 3, nothing else. The instructions as printed were wrong - I had forgotten these until I checked my ancient marked-up schematic. They came up on the old forum but that's a lot to wade through. Here's a link to the old forum, archived on Audio Asylum:

http://www.audioasylum.com/forums/bottlehead/bbs.html

You can do a search on "Paramour" and get the 200 posts thought by the search algorithm to be most relevant. The algorithm is not very smart though.  :^)

 

[Paul Birkeland]

Here's an image to show one of the mods you speak of.

As far as heater winding ground references go, there's a green pair of wires leaving the power transformer and going to the 12 pin socket.  Those green wires will attach to some socket pins.  If those are the only things attaching to those socket pins, then the winding is floating. 

As far as mods go, the gen 1 Paramour power transformer from Hammond proved to be a bit unreliable and we no longer manufacture the replacement that we came up with.  When I get Paramours in for repair that need new power transformers, the only ones we currently have that work properly require adding DC heaters in the process, so that's a nice upgrade (this is not going to be something ever offered as a kit though).

 

[patrickamory]

I think maybe the image didn't attach?

On my amps, the two green leads are the only connections at the tube socket. So I'm guessing I should connect B9 to T14 as Paul Joppa proposed?

And what about the other mod - should the 270k grid resistor be moved from A3 to T17?

 

[Paul Birkeland]

I got that image attached for you.

B9 to ground is a good idea.

 

[patrickamory]

Thanks Paul! Both changes now made in both amps.

One amp now has about 5 seconds of noise when turned on that wasn't there before. Then that vanishes. Normal?

Not quite right - the noise returns intermittently. It's not hum - more like static. In reheating the B3 solder joint, I may have damaged the stopper resistor, which is very close to the joint. Should I replace it? Or is it more likely to be a bad solder connection somewhere.

Difficult to get under the electrolytic to solder T14 too, with the top plate glued to the frame...

 

[patrickamory]

I guess I should describe the noise as "buzz."

 

[patrickamory]

Reversed the grounding mod tying B9 to T14 and the noise is gone.

More bass too... I think I'm going to leave the grounds floating.