2. amps-preamps
  3. 1350004669

Replace volume pot

Hello,
My preamp has a Noble volume pot at 100K ohms.
I like the sound of the preamp in my system so I prefer to keep it. However, I'm having to run the preamp with volume control at almost max rotation to produce a moderate sound level. Also, I like my Monarchy amps and do not want to change these. A friend tracked down a Noble pot (same physical dimensions and pin configuration)at 50K ohms.
I'm hoping to replace the pot and not alter the sound characteristic/performance of the preamp.
Any concerns with performing this swap?
pdspecl
pdspecl OP
254 posts
 
Problem is not the volume pot or mismatch from preamp to amp.
I disconnected the XLR cables and connected RCA cables to the the Monarchy amps. My gain has increased dramatically. No more issue. Very interesting that the different cablee configuration runs very different levels on the same amp.
ivan_nosnibor's avatar
ivan_nosnibor
1,052 posts
 
I suspect that your preamp's volume pot would have malfunctioned on both the single-ended outs AND the XLR outs if it were to blame. I'm guessing at this point the fault lies inside the preamp's single-ended output stage. I've run my pair of SM-70 Pro's both single-ended and balanced (through installed Goldpoint attenuators) and there certainly was no noticeable difference in gain, of course. Hope this helps.
ivan_nosnibor's avatar
ivan_nosnibor
1,052 posts
 
Sorry, I mean the fault lies inside the XLR output stage, of course.
pdspecl OP
254 posts
 
The preamp is single end only. So the cables I had were single ended for preamp side and XLR in the other end.
Went back to using a cable that single ended on both ends. Issue resolved. My guess is that if the preamp had XLR outputs and I went XLR to XLR this issue would not occur.
kijanki's avatar
kijanki
4,432 posts
 
Marakanetz, 50k and 100k pot set at exactly same angle provide almost exactly same loudness since its operation is ratiometric - resistance have nothing to do with it, I used word "almost" because there is not two exactly same pots, even with the same value. Value is roughly selected by the reasons I mentioned before. One designer might select 50k while another might select 100k since it is not that important. It does not change gain.
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