original RS "large"pots

[beaulieu]

Finally found an original 5k pres pot for my 69 plexi. I got a reg body and large body 5k also some other values as well. They were the add a shaft where u cut the shaft to size and then push it in body!

[neikeel]

Unusual for a 69 to use those pots (typically used 63 to 67) the CTS are more usual from late 67 to early 70s.

[beaulieu]

Here is a pic of my amp with large pots. The RS 5k new pot looks exactly like my 1 meg pots. This amp from 69 has the same pots and same color wires as mine. It was made 3/27/69 3 days after my birthday.I suspect mine was made close to the same time . It would Be cool if mine would of been made on my B-Day..However my sticker is long gone! Mark
Here is mine (1st pic)

Hers a 69 superbass from amp archives notice the input jack and pot wiring.Id say the same person did this amp and mine. Hey Neil...Ive been reluctant to money/restore this amp I have but as you can see its far from mint.Would you leave it alone or give it a workover? Sounds fine but could be cleaned up some.

[neikeel]

Yep looks right!

Interesting they must have got a batch of 1M Rs pots in (or found a box of them left over?).

Is yours back to stock now or are you still running it as a 'custom blend' of SB and SL?

Wonder how many amps had the presence pots replaced needlessly due to a 'scratchy pot'?

[Tazin]

Actually, it's not that uncommon to see the large 2w RS pots (rebranded Clarostat) mixed with the CTS/AB pots in the '69 amps. Most of the time it's just the 1 Meg pots being RS, but once in a while you'll see a 5K or 250K RS mixed in with the CTS/AB pots. While I'm on the subject, sporadically Marshall used 1/2 watt DCC pots (for the 1 Meg), and also another RS rebrand 2w pot (looks like the AB or PEC pots) for the 250K in '69. As Neil mentioned, the CTS/AB pots were the "staple" from very late 1967 thru the late 1970's.

[beaulieu]

I saw several amps from 69 on amp archives with the large/small pot configuration. Hey Neil....the amp is a mix still superbass/lead. 56/250 .1 PI the rest is lead spec. I always seem to favor a mix if im playing an amp(feel) I like the bass spec amp when someone else is playing them though. I put this amp and my 68 50 build to stock specs but always go back. Wonder if I should leave the 69 alone or totally rebuild it? Mark

[neikeel]

I saw several amps from 69 on amp archives with the large/small pot configuration. Hey Neil....the amp is a mix still superbass/lead. 56/250 .1 PI the rest is lead spec. I always seem to favor a mix if im playing an amp(feel) I like the bass spec amp when someone else is playing them though. I put this amp and my 68 50 build to stock specs but always go back. Wonder if I should leave the 69 alone or totally rebuild it? Mark

I would not do a total rebuild, personally the patina of the original is impossible to reproduce and it is worth much much more money in stock condition with just neatly pro installed filter caps.
I would remove the 0.68 and 2k7 and the 0.68 on V2a for stock SB (maybe keep the big cap on the pot. Then build a new 100w SL with all NOS parts (ie Iskras) with exactly the same wire colours, layouts etc use the best iron I could but probably install a PPIMV on the clone to tame is a little (unless you have attenuators).

[page361]

I have a 69' JMP 50 (built mid July - 100% plexi circuit disguised in a metal face panel) ...the only changes it has ever seen in it's 44 years are two of its CTS pots being replaced - one 1 meg and the other a 250K. I kept the original pots...replaced them with Alpha's, but am desperate to try and find originals...an impossible task I know. Wish they were repairable...otherwise I'm tempted to go back and install a couple of early 90's CTS pots I have and (if they fit - which they seem to be same size) simply replace the backs of the 90's CTS pots with the originals.

I know a couple of pots being the only parts replaced and solder joints ever broken is not a huge deal at all, but I am on a mission - it's consuming me...

[Strat78]

The 68 plexi George was cloning had the 1M RS pots as well. By the way, if you do take out the V2A .68 chicklet, I,d be glad to take it off your hands or trade it for a .68 mustard.

[beaulieu]

Hey neil Sounds like a plan. Never thought to clone my own amp! That will now be one of my projects. Building a clone of my own plexi... Mustards, Iskras ,board, tube sockets, china hats,belling Lee Fuse Holders.I have a UA so no Master vol. So are you saying to leave the clone stock as well or put the "lead" mods on the clone?

[neikeel]

Hey neil Sounds like a plan. Never thought to clone my own amp! That will now be one of my projects. Building a clone of my own plexi... Mustards, Iskras ,board, tube sockets, china hats,belling Lee Fuse Holders.I have a UA so no Master vol. So are you saying to leave the clone stock as well or put the "lead" mods on the clone?

Build it as a full Lead amp with correct turret positions for the 68k input resistors and the V1 cathode Rk. Take Strat78 up on his offer and use two 0.68uF mustards . Use proper lead tone stack and 22nF PI couplers etc. ie what your amp would be if it were a proper lead amp. I would get the wire routes and funky colours of wire that Marshall used on your input jacks and controls. These were peculiar to that early 69 plexi period. I think that George and Greg Germino use a mix of pots (CTS and the PEC) for tonal reasons too.

[beaulieu]

I have another RS 1 meg "big pot" Now I need to start all over 2 get 2 more and the 5k...well actually no I will just use new style pots this time. Took a few years to find these. I did receive a reg 5k RS pot and I guess I could use that. Also received 2 2 meg RS large pots and about 5 others that were dual pots. dual 500 I think one was a 1 meg/500 and the backs were a little different. They were black with terminals on the back. I guess a few pics are in order!