Old vintage pots, where's the mojo?

[M Fowler]

I like to use 3/8 thread and 3/8 length custom Alpha pots made for Mojotone along with mojotone CTS pots of same size 3/8 x 3/8.

Probably 10% taper as stated for CE Distribution.

However, for Dumble builds with short pots I have to resort to get the 2kL presence pot from Mouser and other values from CED.

Mark

[renshen1957]

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

Hi ToneMerc,

I noticed similar, I used Scotch Brite abrasives and then steel wool, but the recent ones have an anti-solder shield that is about as conductive as plastic. A friend uses a Solder Gun and fries them. Almost easier to use a washer with a lug to solder the grounds to.

Best Regards,

Steve

[groovtubin]

What i do to makem like i needem, is simply lightly sand the trace for higher values, and add pencil lead for lower values, works like a charm, i`ve saved LAOT of $$ doing this, no prob`s yet!

jim@Omegaamps.com

[Mark]

I don't like Alpha pots as they are unreliable, I've seen the wiper go open circuit as well as the other lugs. This hasn't happened on other brands of pots. The taper is only there for perceived change, though certain sweet spots may be easier to dial in with a different taper.

As far the different sounds of the pot, I can't say that I could pick the difference in a double blind test. I'd want to switch between the two different pots in the same amp any other way allows too many variables. Even better if you record the results.

[hitchcaster]

im very interested in those 30% pots!

ive done lots of listening and experimenting... all the different amps like different types of pots.. i have no idea why.. for dumbles, alpha's do sound really good in most postitions. you have to go thru a bunch of them because the values are all over the place (mark all your pot values and then try a few extreme values to get the ballpark idea of what works). the PEC type pots sound not right to my ears in most postions on a dumble, not all though. in blackface fenders ive got some old cruddy NOS pots and in some positions they sound really great, and so do the PEC... trainwrecks seem to be the opposite and PEC or RV4 type pots are the magic ones and alphas sound like crap... i think there also is some magic in the 30% taper thing, and it has nothing to do with where you set the knob. some guys know this and have their own pots made
i haven't tried the carbon PEC's, only the stock plastic and allessandro ones.. ill have to get some of those!

[Mark]

How did you do your testing?

How were you able to eliminate all the other variables when comparing pots and how they affect tone?

[talbany]

Here is the best way to go about this..

Find 2 1M audio pots CTS 30% taper out of either 60's or 70's Fender..I found mine on E-bay..
Find 2 100KL CTS and if you can find one 250K 2-35 Treble pot same as used in earlier Fenders.. Theses are the ones that will have the greatest impact on the overall tone.. Volume, Drive, OD Level, Master, and Treble pot..
Build the amp with Alpha's first then do the switch..

Good Luck!!

Tony

[CHIP]

Tony, Are the 2 100KL CTS pots old stock, or are they just current CTS?
I have also found that I like my Dumble type amps much better after changing at least the Vol. and Master pots to CTS.
I would still like to get a hold of 2 Fender 2-35's for the treble pots.

[hitchcaster]

Here is the best way to go about this..

Find 2 1M audio pots CTS 30% taper out of either 60's or 70's Fender..I found mine on E-bay..
Find 2 100KL CTS and if you can find one 250K 2-35 Treble pot same as used in earlier Fenders.. Theses are the ones that will have the greatest impact on the overall tone.. Volume, Drive, OD Level, Master, and Treble pot..
Build the amp with Alpha's first then do the switch..

Good Luck!!

Tony

very good suggestion... he knows.... the downside is (IMHO) sometimes you get some bad (out of spec/etc) vintage pots so it helps to try/have more then one.
another suggestion, try a PEC pot for the volume on a blackface fender

[Mark]

The odd thing is with all the repro gear out there these pots have slipped through the net. If the 2-35 treble pots works as well as the 350K tapped pot in my Bandmaster than it would be awesome, That pot works really well!

[67plexi]

I am no expert on amp building one thing with vintage pots is balance.
I only have 4 D style builds so far but all have vintage CTS pots.
Volume 1 Meg audio, Treble 2-35 250k, Middle 250k linear, Bass 450k linear,
The rest of the pots I will use; A/B, PEC, CTS.
Next the trimmer pots CTS only you can dial them in less than 3-4 seconds.
Now, resistors make a huge difference in the pre amp 1% Mepco/Electra rule.
The Dale RN65D is harsh sounding to my ears. Other good resistors;
Piher, Iskra, Blue RCA, Beyschlag, IRC.
The sad thing is gathering the correct parts takes time.


Steve.

[talbany]

I am no expert on amp building one thing with vintage pots is balance.
I only have 4 D style builds so far but all have vintage CTS pots.
Volume 1 Meg audio, Treble 2-35 250k, Middle 250k linear, Bass 450k linear,
The rest of the pots I will use; A/B, PEC, CTS.
Next the trimmer pots CTS only you can dial them in less than 3-4 seconds.
Now, resistors make a huge difference in the pre amp 1% Mepco/Electra rule.
The Dale RN65D is harsh sounding to my ears. Other good resistors;
Piher, Iskra, Blue RCA, Beyschlag, IRC.
The sad thing is gathering the correct parts takes time.


Steve.

Vintage CTS's...Prpoerly Seasoned Iron..All the resistors Steve mentioned..

Icing on an already sweet cake..

Tony

[ToneMerc]

Vintage CTS's...Prpoerly Seasoned Iron..All the resistors Steve mentioned..

Icing on an already sweet cake..

Tony

Tony back about a dozen years ago I was firearms consultant to a shop that cryo treated parts for some NASCAR and NHRA engine programs before they took that stuff in house. In turn I got to cryo treat any possible items I wanted too, even running my own recipes. At the time it never dawned on me to treat amp parts.

Do you know of any shop that cryo's output transformers as a "seasoning" process?

TM

[vibratoking]

I don't know of an specific amp builders crygenically treating transformers, but there are plenty of treaters that claim they do it. Here's one:

http://www.nwcryo.com/Electronics.html

[talbany]

Vintage CTS's...Prpoerly Seasoned Iron..All the resistors Steve mentioned..

Icing on an already sweet cake..

Tony

Tony back about a dozen years ago I was firearms consultant to a shop that cryo treated parts for some NASCAR and NHRA engine programs before they took that stuff in house. In turn I got to cryo treat any possible items I wanted too, even running my own recipes. At the time it never dawned on me to treat amp parts.

Do you know of any shop that cryo's output transformers as a "seasoning" process?

TM

Mike

The only person I know experimenting with Cryos in our world is Seymour Duncan.. http://www.seymourduncan.com/newproduct ... ickups.php Zephyr Pickups.. I have been wanting to hear a set of these to see if there is anything to such treatment..The concept does seem intriguing don't it!!

Supercooling materials renders permanent improvement to their grain structure. Also an established enhancement in high-end audio, where cable, vacuum tubes and even entire electronic components are cryogenically treated for improvements in clarity and realism, we achieved similar results for guitar tone by cryogenically treating completed pickups, copper and silver alike. Cryo treatment enhances string definition and boosts the "way huge" potential of your guitar.

Let the Voodoo Begin..

Tony