Super lead v2 bypass cap

[snakej200]

I want to get a v2 bypass cap for my 1975 super lead. From what I understand it’s simple to install. Could someone show me exactly what capacitors (I would like to try a few different values) to get and where I can get alligator clips to try them. Links would be awesome!

Thanks in advance

 

[Jon Snell]

There was a version circa 1970 that used a 680n capacitor that wasn't very successful as it sounded very shrill when fitted. Any capacitor across the cathode may over drive the next stage.

 

[matttornado]

I have a 0.68uF orange drop there. I tried a 330uF and didn't hear much of a difference. I had them hooked up on a switch while listening. I found that adding a cap there makes a very subtle difference overall, at least in my 74 Superlead.

Amazon has alligator clips.

 

[snakej200]

I have a 0.68uF orange drop there. I tried a 330uF and didn't hear much of a difference. I had them hooked up on a switch while listening. I found that adding a cap there makes a very subtle difference overall, at least in my 74 Superlead.

Amazon has alligator clips.

Does the cap need a specific voltage? I was gonna order one of these

https://a.co/d/aUVabUX

Or this to try some variety:

https://a.co/d/ftzrUiG

 

[Pete Farrington]

5V or more is fine.
This shows you the effect http://bmamps.com/CapCal.html
Only a 3dB boost, as the cathode resistor has a rather low value.

 

[snakej200]

I’m under the assumption it is gonna piggy back on top of another capacitor on the board, mind showing me which one? The schematic doesn’t equate to real life for me lol

 

[Pete Farrington]

It'll be piggy backing on to the 1k dark resistor (Piher?) up from the 'sh' of the 'Marshall st1'

 

[playloud]

You don't have to do any piggy backing while choosing a value though. Just alligator clip the test capacitors between the cathode of V2A (pin 3) and ground.

 

[snakej200]

You don't have to do any piggy backing while choosing a value though. Just alligator clip the test capacitors between the cathode of V2A (pin 3) and ground.

I’m not quite sure what you mean by that- I was gonna just alligator clip them to the 1k resistor.

 

[playloud]

I’m not quite sure what you mean by that- I was gonna just alligator clip them to the 1k resistor.

That's fine too, if you can get a decent purchase on the legs (a bit fiddly with the PCB).

The way I would actually do it is using jumper leads (like these). Attach one to the chassis and one to pin 3 of V2, then bridge the test capacitor between the remaining clips on each lead.

 

[snakej200]

That's fine too, if you can get a decent purchase on the legs (a bit fiddly with the PCB).

The way I would actually do it is using jumper leads (like these). Attach one to the chassis and one to pin 3 of V2, then bridge the test capacitor between the remaining clips on each lead.

Dude the alligator jumper leads is a genius idea! I found some on Amazon will be here tomorrow

 

[playloud]

Dude the alligator jumper leads is a genius idea! I found some on Amazon will be here tomorrow

Not sure about "genius" but they are useful to have around!

 

[snakej200]

Anyone know what to expect between what I have now (no cap), .68uf, 250uf, and 330uf?

 

[Pete Farrington]

Anyone know what to expect between what I have now (no cap), .68uf, 250uf, and 330uf?

exclude duplicates
No bypass will flat along the -4.2 dB line.
0.68uF will put the half boost at about 270Hz. By 100Hz and below, the boost has run out.
Anything over 180uF pushes the half boost below 1Hz.
To me, the range 0.47uF to 10uF looks the most useful to tinker with.

 

[snakej200]

exclude duplicates
No bypass will flat along the -4.2 dB line.
0.68uF will put the half boost at about 270Hz. By 100Hz and below, the boost has run out.
Anything over 180uF pushes the half boost below 1Hz.
To me, the range 0.47uF to 10uF looks the most useful to tinker with.

I’ve got an assortment of ceramic caps getting delivered today. I want this amp to be a little more aggressive and focused with less bass like my reissue so I’m thinking it’s gonna be the .68

 

[snakej200]

I’ve got the alligator clips up and running. .68 was ok. I tried a .033 guitar tone cap. Am I nuts if I think that sounds awesome?!

 

[Pete Farrington]

.033 guitar tone cap

Half boost frequency about 700Hz, somewhat akin to a Tube Screamer