Caps for a 60's Selmer Treble & Bass Amp?

[louderock]

Working on my Selmer Treble & Bass MkII. The internal components appear to be all original except for the main output caps. There are some smaller caps on the board that are oval shaped and almost clay-like in texture. One of them was slightly chipped on the clay-like coating and it flaked off. Amp still works but I'm just wondering if this should be replaced. What sort of cap would replace this? Not really sure what all of the different types of caps do.

 

[SatelliteAmps]

If it is working, then I would leave it. Where is it in the amp?

 

[hamfist]

As Adam said, if the caps are not electrolytic and the amp is working fine, there is no need to replace any of them.
For a 60's amp, I would certainly replace any original electrolytics though, unless you are keeping it as a museum piece.

 

[louderock]

If it is working, then I would leave it. Where is it in the amp?

It's a 47000 pf cap connected to pin 6 of V1 and the other side goes to a few resistors and then to the channel 1 Treble pot. But, I'm noticing this treble pot doesn't work as well as it does on the other channel. Just wondering what I would need to replace this one. It's mustard yellow and feels like it's hard clay. Also has B6N on it. Would this cause the treble pot to be ineffective or is it just a bad pot? Based on this schematic, looks like the treble pot is 100k. Is that correct?

http://www.vintagehofner.co.uk/selmer/schematic/tnb7.html

The large electrolytic caps have been replaced. I originally bought this amp from Toneman Don Butler. Great amp!

 

[SatelliteAmps]

You can replace it with a .047uf @ 630v. Sprague, Mallory, Sozo all make good products that can be used in that spot. It may help the treble controls. It definitely won't hurt, and if you don't like it, just put the old one back.

 

[louderock]

Cool. I will order one from Mojo. The Treble pot measures 117k when off and around 60k when at the center position. This is measuring from the center terminal to the right terminal. I assume this makes it a linear pot and I assume it is working fine.

 

[SatelliteAmps]

Sounds linear to me.

 

[louderock]

Swapped the cap in question with the cap from the other channel. Still the same result, the Treble control on the bass channel doesn't really work. When you turn it all the way down, it seems to get brighter - the opposite of what should happen. From 8 o'clock and up there is no real effect. I measured the pot and it seems to work. What else would cause the treble control not to work?

 

[Ian Anderson]

Is that a crock skin amp?

How do you like it?

 

[louderock]

Is that a crock skin amp?

How do you like it?

It's a MkII which is the very next year. Built sometime in the mid-late 60's. Black with cloth on the front of the amp that looks sort of like the Vox cloth.

Sounds amazing. Kind of like a JTM45 meets and AC30. Has super sparkly cleans down low and will really get growly up loud. You can really nail that early WHO stuff with this amp. I play it mostly through greenbacks in an old Marshall cabinet but I would love to hear it through some Goodman speakers which are the ones that came in the original Selmer cabinets. Great amp. Looks like this:

http://www.vintagehofner.co.uk/gallery/gallery3/gallery4/cat26.html

 

[SatelliteAmps]

Treble still not working? I've got one of these at my place. Let me go check and get back to you later.

 

[louderock]

Treble still not working? I've got one of these at my place. Let me go check and get back to you later.

Got it working by snipping the 4700J cap that was across the volume pot. Now I need a cap. Assuming that's 4700 pf.

 

[Ian Anderson]

I played a crock skin T&B years ago and it was a great sounding amp! I tried finding one and couldn't do it.

 

[SatelliteAmps]

There are a few of the croc T&B's floating around for sale. Most over $3k though. I've got a few Selmers but no croc's.