Old vintage pots, where's the mojo?

[ToneMerc]

Choose 450 style particulars with a 30% audio taper

http://www.ctscorp.com/components/Datasheets/450.pdf

TM

[glasman]

Choose 450 style particulars with a 30% audio taper

http://www.ctscorp.com/components/Datasheets/450.pdf

TM

Request J taper, this is there 30% taper.

[husky]

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.

Alphas and AB unless custom ordered have a two step linear sweep on their Audio tapers.
The CTS taper is almost as nice as the PEC military but.....
FYI the CTS is now made in China.

[martin manning]

Alphas and AB unless custom ordered have a two step linear sweep on their Audio tapers.
The CTS taper is almost as nice as the PEC military but.....
FYI the CTS is now made in China.

Seems like even vintage pots used essentially two linear sections to approximate a log taper. Measurements of old guitar pots by Glen K and an old (1953) Centralab data sheet posted in another thread https://tubeamparchive.com/viewtopic.ph ... intage+pot by Tonemerc (and reprised here for anyone that missed it) shows what they were doing. Maybe it's the finer points of the transition between the two sections that makes the difference. Re the country of origin, it's not impossible to get good quality in Chinese-made components. I think that's determined by the spec and the dilligence of the customer.

[ToneMerc]

FWIW, I have another Centralab chart from 1937 and it has the C2 taper at about 26%-27%, whereas the 1953 chart has that taper at 10%.


TM

[ToneMerc]

FYI, these are not 30% taper, around 9-10%

http://www.ebay.com/itm/N-O-S-CTS-USA-1 ... 1365429776

TM

[renshen1957]

Could a transformer survive the process??? Aren't they wire, paper and goop??? I just wonder if the non metal components would come out damaged or in worse shape than before..

I don't see why it wouldn't survive as it's a relative dry process. Although I remember one company that ran quite a few ads in the gun magazines in the late 90's that wasn't so. Come to find out they a used a homemade device consisting of a large freezer and a liquid nitrogen sprayer. This company was literally spraying liquid nitrogen down the bore which checked the surface causing it to appear like alligator hide when you viewed it using a borescope. They damaged so many rifle barrels that they eventually filed for bankrupty protection.

TM

Dang! I don't know what the process really is. I did some work at Cryo Cell which freezes cord blood for long term storage.. Looks super expensive to do it right; to freeze cells without damaging them.... i don't know what the process looks like, but I guess if you can freeze human cells and thaw them out, why not anything else???

Hi

As to Pots, low temperatures on carbon traces being affected, I purchased some pots, hook up wire, and other parts from Callaham (but not the treated Lindy Fralins PUPs), I couldn't distinguish any difference between these and non-treated.

The Callaham Strat Bridge did demonstrate a significant tonal change but this part was not "frozen." It was worth every penny.

Cryogenic treatment was a spin-off for research from WW2 and in time NASA's interest as to the behavior of metals in the low temperatures of space. Scientists found that metals frozen to low temperatures showed more resistance to wear.

An extension of the tempering process. CryoTech and others originally experimented with the possibility of increasing the life of metal tools to anywhere between 200%-400% of the original life expectancy using cryogenic tempering instead of heat treating.

Then the mojo factor sets in:

Post 1990's the following where treated Vacuum tubes, Guitar Pickups, and Brass Instruments (improved sound quality); baseball bats and golf clubs (greater sweet spot); racing engines (greater performance under stress), firearms (less warping after continuous shooting), knives, razor blades, brake rotors and even pantyhose.

I can envision the wear aspect on metals, however bats & clubs "sweets pots", and non metallic pantyhose is stretching it a bit.

Vacuum Tubes are so variable as devices, I can't say that anyone has scientifically investigated this to my knowledge in a double double blind comparison, or by spectrum analysis. Frankly, the improvements in Chinese tubes (the audiophile types) came about from research, sourcing better material (from outside of China), and the assembly by highly skilled and experienced employees. I won't believe that a 48 trip from room temperature to low Kelvin temps and back again is going to make a standard production 12ax7 from Shuguang into a NOS Mullard sonically, or increase the life expectancy of its cathode material.

As to Trombones, I leave this to Brass Players.

Best Regards,

Steve

Brent M, a little of topic, FYI:

Human blood cells can be frozen without internal ice crystal formation (vitrification) damaging the cell if a Solvent, Dimethy sulfoxide, better known by its initials DMSO plus Glycerol are present.

DMSO is very similar to naturally occurring Methylsulfonylmethane found in the body.

For red blood cells the optimum cooling rate is very rapid (nearly 100 °C per second), whereas for stem cells the optimum cooling rate is very slow (1 °C per minute).

Don't try this at home.

Dont' tell the makers of Austin Powers or the Encino Man about the above, it would ruin a good suspension of disbelief. Only the movie Iceman has a passing reference (one line) about DMSO.

[brentm]

FYI, these are not 30% taper, around 9-10%

http://www.ebay.com/itm/N-O-S-CTS-USA-1 ... 1365429776

TM

I'm sure you guys have seen these... but Dimarzio has a custom taper CTS pot in current production. I couldn't find a graph of the taper on their website...

http://www.guitarcenter.com/DiMarzio-1- ... 1130469.gc

[ToneMerc]

I'm sure you guys have seen these... but Dimarzio has a custom taper CTS pot in current production. I couldn't find a graph of the taper on their website...

http://www.guitarcenter.com/DiMarzio-1- ... 1130469.gc

The pot pictured is actually a CGE. Now I have not verified it, but supposely the taper is slower than 10%.

TM

[jborders5]

These are definitely close to 30% taper: http://store.rsguitarworks.net/RSG3.html. I've used them in a couple of my Teles, but not in an amp yet. The only downside is they're really low tension and will feel different from a standard Alpha or CTS from Mojo, Antique Electronic/CE, etc....

[ToneMerc]

These are definitely close to 30% taper: http://store.rsguitarworks.net/RSG3.html. I've used them in a couple of my Teles, but not in an amp yet. The only downside is they're really low tension and will feel different from a standard Alpha or CTS from Mojo, Antique Electronic/CE, etc....

I used a couple of those in my 183 build and currently using one in my HV rebuild. The pot in the current build is 260K and measures just over 78K @ 50%. I need to plot the entire curve.

TM

[Mark]

So you bought a 250K pot and a 500K pot.

How did the taper feel as opposed to standard 10% taper pots?

I don't think a 10% taper cuts it and a linear taper feels just as bad to me.

Are the RS pots worth the extra expense?