Pots is Pots...or are they?

[aceonbass]

So, I've got this hip new multi-meter and I just have to test everything I've got with it to get the hang of it. Tested the RIHS in my 4008 (10.59k), it's slightly overwound toaster (8.6k), and all my HB1's (between 14-15.1K). Then I move to the tone caps (around 46-49uF). Then I move onto my volume and tone pots. Like a good Rick-o-phile, I bought all these from RIC or their dealers. These were all supposedly 250K pots. I say supposedly, because when I tested them they were all off on the low side at around 175-195K. That's about a -25% tolerance. Now I know why RIC switched to 330K pots. I don't have any of these in anything anymore, but I'll bet they're close to 250K, which is fine for the volume pot on a toaster or a hi-gain, but not as a volume on an HB1, or a tone for anything. So I've got my first order of Bourns pots because I've read good things about them and the 250K pots spec out between 229-262K, well within a 10% tolerence either way. The 500K pots spec out at 449-562K, again within 10%, but most are within 5%. I'm thinkin' the stock pots must be having a real dulling effect on the sound, so I decide to start rewiring everything starting with my 4008CS and it's newly aquired vintage pickups. The only stock parts I kept were the selector switch and output jack, both Switchcraft. Besides the Bourns pots, I also used new Cornell-Dubilier .047 polyester film caps(same ones RIC seems to be using now), which are within 5% of rated spec, and 22 gauge wire. The difference was like night and day. The sound was much clearer and more open and better defined. Next up was my 4003 Lemmy tribute bass. From the bridge forward it has an HB1, another HB1 and a bass hi-gain. It had been wired Volume Volume with a selector switch between the middle and neck pickups. I decided to change it to VVVT for more versatility with no slector switch (ROS is now the same thing in both channels). I plan on replacing the hi-gain with another HB1, so I used all 500K pots, and since pretty much everyone else uses .022uF tone caps with humbuckers, that's what I decided to use with my tone control. Again, the sound was more open, though not quite as crisp. Having a volume control for each pickup (the ones with the 4004 knobs) makes for a pretty much infinite combination of tones, even with just one tone control. Depending on where the volume knobs were in relation to each other, I can get this neat "twist" in the sound that reminds me of a subtler version of Alembic's Q control. The Bourns pots are butter smooth too. I'll be digging into my 4004s this week too, while my custom double neck has already been completely gutted for new components and a different wiring layout.

[nukebass]

Are the standard RIC type pots you tested CTS? I always heard those were a decent pots so a 20% tolerence surprises me a little bit. How do the Bourns pots compare price wise to a CTS pot?

Why do you say the 330K pots aren't good for tone control?

This kind of stuff fascinates me and I may have to try some experimenting myself when the warranty on my 4004 expires. I usually tend to melt things with the soldering iron, though

[cjj]

CTS pots are decent, but it depends on what you buy. They come in several tolerance ranges, 10%, 20%, and 30%. Probably better with special ordering. So, it sounds like you got some with the wider tolerance range. What are the numbers on the pot?

[coolhandjjl]

I thought I read that the original 4001's used 500K for tone and 250K for vol. Since my 2009 4003 has the push/pull feature, and that one is a 500K, I changed the neck tone to 500K also. On my 1993 4003s that will get the RIHS, I also added the tone cap selector switch, so I changed that neck tone pot to 500K as well. These were either CTS, Bourns, or Alpha pots I had in my parts drawer. My meter is not that accurate as an ohm meter, so I can't say with any degree of certainty what the pots are exactly, but since I overshot Ric's modern production values, I'm probably safe for getting a very open tone.

When I was running the humbuckers in my 4003s, I used .33uF sprague orange drop caps. They are available if anyone wants them.

[aceonbass]

All of the RIC pots I tested (part#07341 dated 30th week of '04) were made for them by CTS, and the best one had 20% tolerance. The rest were off by 25%. From what I've seen, CTS pots with tighter tolerances are $10 or more, while the Bourns pots were about $3 each. The CTS supplied push pulls are actually more accurate, which surprised me since they're mini pots. Industry standard specs for tone pots is 500K, while volume pots are 250K for single coil and 500K for humbucking pickups, so why would I want to use 330K pots (which I'll bet are nowhere near 330K)? RIC's schematics used to reflect these pot values for these applications, but since the 330K pot was introduced, they've gone back and revised the part numbers and pot values on many of their schematics. I'm betting the 330K pot will spec out at around 250K, and that's fine for single coil volume, but I believe it will choke off an HB1. I wouldn't mind having a couple to use as volumes if anyone wants to trade for some of the 190K pots.

[coolhandjjl]

Maybe I shouldn't open that can of worms, just one more thing to worry about.

Dane- what meter did you buy? Mine is a dog.

[aceonbass]

I got it from Radio Shack. Catalog#22-811. I think it was $60. Fortunately you shouldn't have to worry about the pots in your "V57". The RIC/CTS push pulls seem to spec out within 10%, and testing one of the CTS pots from the same batch as yours gets me 506K. I don't understand why the ones they made for RIC are so much less accurate.

[cassius987]

Industry standard specs for tone pots is 500K

Not that I'm aware of... most of the Ernie Ball basses with passive option have 500K volume, 250K tone. And Fender usually uses a single tone at 250K. (Of course the tolerances on these are who knows what.)

A Ric, with two tone pots that can be used in parallel, is going to be a more complex story because the resistance against loading down those frequencies will be half. I could see possibly using 500K pots in a Ric for tone (final R=250K), although I'm perfectly happy with the stock harnesses in my 2007 and 2008 basses, which probably load down to somewhere around 150K for both volume and tone in the mono mode.

[ken_j]

Remember that in a Rick (with two volume controls, as in a 4003) the volume pots are wired between the selector switch and the output. Both pots are always in the circuit regardless of the selector switch position. If the volume pots read 250K then there is 125K load. If the pots read 190K then there is a 95K load. The difference is only 30K, so the wider tolerence pots don't have as large as an effect as one might think. No doubt that the lower the resistance the more the high frequencies will bleed off.
When I had my 650 with HB1's I found that 500K volume pots seemed to give the instrument more definition and a brighter tone. 250k pots give a warmer tone.

[aceonbass]

I should have said rule of thumb instead of industry standard as Fender and MM especially are different in that respect. All I know is, I expect my parts to be in spec with the wiring diagrams. They weren't and now they are, and the two I've done so far sound better.

[ken_j]

... and the two I've done so far sound better.

That's all that treally matters. You are the one that has to be satified. All the reasons you mention is why some guitarist prefer 1 M pots, very bright and clinical. I had a friend that ran his pickups straight through with no pots, volume or tone. He played alot of metal.

[johnhall]

I just measured a whole box of our standard 330K pots as received from CTS, using a high-end Fluke meter. One was bad at 1.2M ohms, perhaps 10% were right on at 330K but most of them measured about 290K. Except for that bad one, all were within the +/- 20% spec, which is standard for most consumer grade pots.

We're going to speak with CTS and see if we can't zero in a bit better on that 330K number as we had previously determined that to be the sweet spot for us. That might include upping the tolerance and/or the value to get there.

We're always looking at other pot makers as well . . . Bourns certainly are well regarded . . . but CTS still has the best value for money, as well as a good record with us for accurate and on-time deliveries, a very important factor in the way we operate our shop.

[tmossman]

The stacked 500k/500k CTS pots I recently purchased varied from 460k - 510k. I ordered more (5) until I found a matching set. I wasn't able to find a 5% tolerance stacked 500/500 pot (I use Digi-key and Mouser).

[aceonbass]

I don't think 10% tolerence is bad, and I probably couldn't hear the difference, but 25% just seemed way too much and it was audible.

[johnhall]

The difference in price between a 10% and 20% pot is almost a factor of 10, so there really has to be a good reason to justify such tolerance, especially when the amp you're connecting to probably has relatively low precision components in its preamp.

But 25% is certainly not acceptable.