Old vintage pots, where's the mojo?

[ToneMerc]

Let's talk get some updated discusion about the differences in pot brands. Is the magic in the taper or wafer material and if it's indeed the taper, where's the best locations to install them.

TM

[martin manning]

OK, there was some relevant discussion here https://tubeamparchive.com/viewtopic.ph ... highlight= and here https://tubeamparchive.com/viewtopic.ph ... highlight= It always seems to come back to the taper, or defects like noisy scratchy behavior. Bob-I thinks there is something more to it than that, but I don't know. This CTS sold by AES looks about as good as any vintage pot I've seen with its 3/8" brass bushing and stamped saddle. I'll probably go with these for my next build, but I can't convince myself to replace the functioning Alphas in the stuff I've already completed. I'd really like to try some kind of A-B test.

[jelle]

Guys, thanks for that. I was thinking of getting stuff for both the Trainwreck and Dumble guys. 1M-A, 500K-A (?) and 250K-A like the pot in the pic posted above and in 30% taper. I think these are the values we need. I am using the ones in the pic and from Tubesandmore and these are 10% taper. The upside is that they are a dream to solder coax to.

The Ratio and level pots are 100K lin so we will not need those.

I am not in a big hurry to get these due to the costs of the large number that needs to be ordered, but if we can combine, that might speed things up.

I do believe that the vintage pots sound a bit different. However, the fact that we can get 30% pots that are great to solder to is all I am personally interested in.

Who's interested?

Jelle

[Structo]

CTS also makes one like the one in Martins post with a cast saddle.
Also the older button back style.

It seems logical to me that the composite that the resistance track is made from would influence tone.

That is, if it is pure carbon it would sound one way, if it is a conductive plastic it would sound another way.


The taper seems like it would also play a part in the tone.

If you think about when looking at the Dumble tone stack, all the signal at one point passes through the Treble Pot and volume pot, so that pot would greatly influence tone if it indeed does.

[diagrammatiks]

having a good 30 percent taper is most likely the only difference between old pots and new ones.

I can't imagine the sound being influenced that much.

mechanically the older non-sealed pots were made in the US by companies that were also making several types of other pots so there was some consistency in the manufacturing.

[dreric]

Please forgive my ignorance, if that is the case. I've been thinking about this for a while and spent some time trying to get the pots right for my current 183 build.

Seeing that the pot is a variable resistor doesn't the taper indicate the rate of that variability as you turn the control. A one meg pot is a one meg pot in resistive value the taper would seem to affect, not the tone, but the feel of the pot as you turn it.

I'm used to my Fender amps, I'll play, tweak, play some more the taper makes the pot feel normal to me. Some of my builds with 10% tapers feel too rushed, like the tone is changing too fast.

At any rate I'd be into getting some made up 1 meg, 250K, 500K audio.

Eric

[ToneMerc]

It seems logical to me that the composite that the resistance track is made from would influence tone.

That is, if it is pure carbon it would sound one way, if it is a conductive plastic it would sound another way.

I agree with this as I don't think the PEC's or the Clarostat's RV4's sound good in all circuits.

TM

I'm going to clarify this as not all PEC are the same. I remembered that the PEC's that used a two Marshall builds I got from Metro and those George ordered as are carbon. However, the ones that I can get locally are plastic and I can swear there's a difference.

TM

[ToneMerc]

The upside is that they are a dream to solder coax to.

I do believe that the vintage pots sound a bit different. However, the fact that we can get 30% pots that are great to solder to is all I am personally interested in.

Who's interested?

Jelle

Speaking soldering has anyone noticed that Alphas are not as easy to solder as they used to be and there appears to be a different type of coating?

TM

[martin manning]

If you think about when looking at the Dumble tone stack, all the signal at one point passes through the Treble Pot and volume pot, so that pot would greatly influence tone if it indeed does.

The same goes for the FET output trimmer, the OD entrance trimmer, level and ratio pots, and the master volume, plus all three of the D'lator pots.

It seems logical to me that the composite that the resistance track is made from would influence tone. That is, if it is pure carbon it would sound one way, if it is a conductive plastic it would sound another way.

Aparently under certain conditions carbon comp resistors cause distortion. See http://www.geofex.com/article_folders/c ... oncomp.htm Keen's article suggests that 100V or so is needed to produce the effect. I don't know if pot elements do this, but those pots see nowhere near that. The voltage across the treble pot is low since the path to ground includes the other two tone pots, and similarly for the volume pot since its input is the treble pot output.

The taper seems like it would also play a part in the tone.

Taper is only the rotational position to reach a given fraction of the total resistance. It might make the control easier to set (finer adjustment around the critical range of resistance), but an eqivalent position could be found on pots of two different tapers. This seems to be important for guitar pots.

[erwin_ve]

Who's interested?

Jelle

I am!

[diagrammatiks]

It seems logical to me that the composite that the resistance track is made from would influence tone.

That is, if it is pure carbon it would sound one way, if it is a conductive plastic it would sound another way.

I agree with this as I don't think the PEC's or the Clarostat's RV4's sound good in all circuits.

TM

this could be true. I'm sure the PEC, claro, cts, and alpha have their own track element production.

The upside is that they are a dream to solder coax to.

I do believe that the vintage pots sound a bit different. However, the fact that we can get 30% pots that are great to solder to is all I am personally interested in.

Who's interested?

Jelle

Speaking soldering has anyone noticed that Alphas are not as easy to solder as they used to be and there appears to be a different type of coating?

TM

rohs.

[blowafuse]

I would be in for pots going to 11

http://www.youtube.com/watch?v=EbVKWCpNFhY

[renshen1957]

The upside is that they are a dream to solder coax to.

I do believe that the vintage pots sound a bit different. However, the fact that we can get 30% pots that are great to solder to is all I am personally interested in.

Who's interested?

Jelle

Speaking soldering has anyone noticed that Alphas are not as easy to solder as they used to be and there appears to be a different type of coating?

TM

Hi TM,

Alphas aren't easy to solder the back of the pots in my experience.

Steve

[ToneMerc]

The upside is that they are a dream to solder coax to.

I do believe that the vintage pots sound a bit different. However, the fact that we can get 30% pots that are great to solder to is all I am personally interested in.

Who's interested?

Jelle

Speaking soldering has anyone noticed that Alphas are not as easy to solder as they used to be and there appears to be a different type of coating?

TM

Hi TM,

Alphas aren't easy to solder the back of the pots in my experience.

Steve

Steve, I never had a problem before as I could lightly scratch them with a dental pick and it was painless soldering. I can't say same about the recent ones I have used.

TM

[renshen1957]

Let's talk get some updated discusion about the differences in pot brands. Is the magic in the taper or wafer material and if it's indeed the taper, where's the best locations to install them.

TM

Hi ToneMerc aka TM,

Some thoughts on Pots from the Resistor Thread.

Structo asked how do you get a pot that is 308k? My suggestion, purchase a pot that is listed as 350K.

From wiring up some Boutique Guitars for a Luthier which purchased their CTS pots in bulk from either StewMac or All Parts, I found that it is a rare day when most of the pots measured 250K as specified.

Out of 24 pots, 3 or 4 would be circa 250k, more than a few were 225k-235K if you were lucky, and too darn many were 213k-218k!

I was purchasing (out of my own pocket) 300k pots for more than one guitar for a big name performer to hopefully get at least 250K and no less than 240K, and sometimes the odd 285K pot would slip though.

I used Military Spec 2W pots cabon comp, possibly PEC before Honeywell/NTE took over distributing, but these were for London Power Power Scaling circuits rather than for tone controls. Most 2W circuits have plastic that I have come across recently for the voltage withstand. Plastic does sound different to my ears.

Bourns Pots, American name-Chinese Pots, from what I've seen a bit better quality than Alphas.

Alessandro's military spec amp pots wholesale at about $12.00 (I get CTS NOS cheaper), never tried them. And the Guitar Pots, Alessandros 1 Watt pots are $37.50 cost from my distributor.

Only thing more expensive is Hi-Fi. Good thing HAD didn't use stepped attenuators: http://www.diyhifisupply.com/node/305

I've been purchasing CTS from CE but only the solid shaft, the nylon doesn't look strong enough to survive life on the road. Fender has a few CTS pots but I couldn't cotton to the idea of paying an extra $2 to $3 dollars for the "Fender" name, unless the taper was special. Knowing Fender, they buy any old stuff in bulk, slap a Fender label on it and charge more. And since the rest of the product line's quality has eroded since the 1960's pre-CBS stock was depleted I would welcome any American (or a Canadian) Made Pot that would do the job, be consistent in feel and taper.

Best Regards,

Steve

Edit/PS I try to use US made components because that is what is a selling point, but made in the USA components are getting harder and harder to find. I've resolved to use the best that is made regardless of origin.