Importance of pot quality in Lar-Mar master volume?

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shakti
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Importance of pot quality in Lar-Mar master volume?

Post by shakti » Sun Oct 07, 2018 12:41 pm

I've tried to search but the Lar-Mar thread is so long I can't really find a definitive answer.

I have only built one amp with a Lar-Mar master volume and used a dual Alpha pot I had. I found out that I actually liked the master volume a lot in that amp, so I'm thinking about adding it to one or two of my other builds for practical purposes. But I am wondering if it makes a significant difference to use PEC pots insted? I know George is a big fan of the PEC dual pots for his master volumes, but IIRC he is using a different type of PPI master volume, is that right? With the Lar-Mar, does it make any sense to buy the much more expensive PEC type? The rest of the pots in these particular amps are Alpha FWIW.

I will try a zero-loss FX loop in these same amps, but that shouldn't have a bearing on my choice, I would assume?
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toner
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Re: Importance of pot quality in Lar-Mar master volume?

Post by toner » Sun Oct 07, 2018 6:36 pm

I doubt it's worth getting a PEC. I have an Alpha (or whatever Metro used to sell) that has worked fine for 11 years of regular use.

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Re: Importance of pot quality in Lar-Mar master volume?

Post by danman » Sun Oct 07, 2018 7:19 pm

No difference in tone that I have been able to hear. The PEC pot does have a smoother taper, especially on the lower end of the range. Readings between both halves are also much closer on the PEC. Alphas can be quite a bit apart.

shakti
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Re: Importance of pot quality in Lar-Mar master volume?

Post by shakti » Mon Oct 08, 2018 11:32 am

Thanks guys! I think for my uses (typically keeping it at around the halfway point or a little higher) the Alphas will do the job just fine.
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neikeel
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Re: Importance of pot quality in Lar-Mar master volume?

Post by neikeel » Tue Oct 09, 2018 4:56 am

I found a fair amount of variability in the Alphas at different knob settings (I had cause to experiment as I had one pot that was faulty and the MV did not work). As a consequence I have not been fitting PPIMVs recently (just using attenuators) but then most have been restorations as time permits.
Might have to try a PEC some time. CTS do a nice Clarostat type dual pot too.
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Re: Importance of pot quality in Lar-Mar master volume?

Post by Roe » Fri Oct 12, 2018 3:41 pm

some dual pots are too unbalanced/assymetric to be usable. One pot reads 220k, the other 270k and the taper also differs
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