hookup wire for crack

keithpgdrb · 5875

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Offline keithpgdrb

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Reply #15 on: December 04, 2013, 06:52:16 AM
here is my repair job.  the original builder took some strange wire paths.  but when I listened, it seems a that it might be hissing a bit less.  interestingly, when I crank the volume, I now hear the ground type hum equally in both channels, but less of it.

I think i am going to start by yanking my resistors I was using to give me more volume control turn.  I can always go back and put them in, but I'd like to get things out of the signal path.  plus, I didn't really have the proper resistors anyway.  and if they might add noise, I want them gone. 




Offline keithpgdrb

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Reply #16 on: December 04, 2013, 06:56:21 AM
here?




Offline Paul Birkeland

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Reply #17 on: December 04, 2013, 06:57:56 AM
Looks good from that shot.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline keithpgdrb

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Reply #18 on: December 04, 2013, 08:10:12 AM
removed the resistors.  I do wish the volume had more turn, but since there is no imbalance, I won't worry about it.

The ground type hum is there, but at a high volume level that I would never use.

Still a slight hiss after about 8 seconds.  would love to get rid of that, but not sure where to start on that.  It doesn't seem to increase with the volume control.

probably time to take some measurements.?



Offline Paul Birkeland

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Reply #19 on: December 04, 2013, 08:17:52 AM
The slight hiss is generally typical tube noise.  There are certain specimens that will fare better than others.  So removing the resistors ended up helping?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline keithpgdrb

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Reply #20 on: December 04, 2013, 08:32:44 AM
I think that it did.  I had some unexpected improvements.  after I shifted and desoldered/resoldered those wires, the ground noise moved from the right channel, to equally in both.  But I thought that overall noise was less as well. I would not have thought just routing wires differently would do much.  It may have been the resolder as well, but whatever.  After I removed the resistors, the ground noise doesn't really become detectable until the volume is Really high.  so I'm just left with the hiss right now.  I would like to eliminate the ground type noise completely, but thats just my OCD.  I know its there, even though it doesn't effect general listening. 

The hiss I can deal with if thats just a tube thing.  have to fine one though that doesn't sound like there is a fly trapped in the right ear cup, and sitting next to a guitar amp that is feeding back.   lol. 

Would it be better for me to use the speedball wire that I originally asked about in this thread?  I can't imagine the radio shack wire being good, but maybe in doesn't matter in its placement.  referring to the page 19 correction.

"Page 19 -  you could change 2" wire from power trans terminal 4 to 22L at the bottom of the page to 3" and connect it to terminal 14U rather than 22L. It will work either way, but this may give a slightly lower noise floor. (This is mostly correct after 4/26 but manuals labeled 4/26/10 say mistakenly 15U rather than 14U)"





Offline Paul Birkeland

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Reply #21 on: December 04, 2013, 08:37:40 AM
The Speedball wire is very expensive, high quality wire, so I would recommend using that.

Wiring layout is pretty critical.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline keithpgdrb

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Reply #22 on: December 04, 2013, 09:29:30 AM
ok, I'll use it.  I was just worried about the difference in thickness.  its an easy change out.
Thanks for all your help here.  Looks like the tube rolling forum is my next stop I think.