'70 superlead conversion to '68 specs?

[Jodyzuza]

Since I got it going in to the shop anyways, I was wondering what kind of mods it would take to get that nice '68 tone out of my '70 besides simply clipping the bright cap?

 

[Joshabr1]

Well what 68 spec are u speaking of?? Lead amps had the big bright cap in 68. The only difference in 68 from 70 lead spec speaking is negitive feedback and filtering. The circuits are identical.

 

[jakub421]

The 70 Marshalls are generally the same as the 68/69 except for filtering and a metal panel.

You might want to try converting it to shared cathode (early 68 s had a shared cathode still), but other than those two things, they are pretty much the same.

Can you post some pics of your circuit?

 

[Jodyzuza]

The 70 Marshalls are generally the same as the 68/69 except for filtering and a metal panel.

You might want to try converting it to shared cathode (early 68 s had a shared cathode still), but other than those two things, they are pretty much the same.

Can you post some pics of your circuit?

Yes! I'm gonna have a photo shoot of my circuit later this afternoon. I will also have a link to a YouTube video of me playing it and also a walk-around of the amp...any advice will be appreciated!!

thanks for your help!!

 

[Jodyzuza]

The 70 Marshalls are generally the same as the 68/69 except for filtering and a metal panel.

You might want to try converting it to shared cathode (early 68 s had a shared cathode still), but other than those two things, they are pretty much the same.

Can you post some pics of your circuit?

I just had the photo shoot...I just uploaded them to an album in my public profile...I appreciate any comments!

 

[keennay]

.

 

[Joshabr1]

There is not a lot of the original amp left there. Great platform to go from though.

 

[Jodyzuza]

There is not a lot of the original amp left there. Great platform to go from though.

Yeah, I know...
can you tell by the pix if there is any mods to the amp that might increase the gain? The amp goes from 0 to moderate gain from 0-1 on the volume, over 2 it's full on gain....I would love to be able to have the gain start after 3-4 so I can at least set it clean or semi distorted...

Thanks for your help!

 

[yladrd61]

With all the mods on that amp the best thing you could do is have all the mods removed try to get it as close to stock as possible and then go from there...... Whoever replaced all the coupling caps with Orange Drops should not be allowed to work on vintage Marshalls !!!!!

 

[Jodyzuza]

With all the mods on that amp the best thing you could do is have all the mods removed try to get it as close to stock as possible and then go from there...... Whoever replaced all the coupling caps with Orange Drops should not be allowed to work on vintage Marshalls !!!!!

What would be a better alternative to the orange drops besides old stock caps? How about sozo caps? The guy who makes them lives in my town...

 

[Joshabr1]

U can buy a full set of mustards on eBay right now for 100$ no .68s but worth it. for new ones I would go w sozos.

 

[jakub421]

Yeah, that amp's been modified quite a bit.

What I would do is pull the board and start from scratch. Definitely much easier than trying to figure out what has and what hasn't been changed. And it will come out cleaner.

 

[Joshabr1]

I agree with these fellas. I would pull the board and build a nice correct superbass or whatever u want out of it. U have a good board and chassis to work with. For the meantime if u want to calm it down. Add the 100pf bright cap in place of the 5k

 

[neikeel]

The board looks fine,

I suggest getting a decent solder sucker and some good quality solder removal braid and remove all the non original parts (there are some original Iskras there (post a pic of the board form above, with pots at the front and valve bases at the back so we can say what should stay or go.

Buy a set of mustards off ebay for $100 or so (there is a UK seller that has 0.68uF but they are £20 a pop. Do the work well and cleanly. Install a vintage type OT and you will have a great players amp (the ground earth looks dodgy, suggest you read this thread here:MetroAmp.com Forum • View topic - 12xxx Larry Ground
It will probably be worth twice what you paid for it. It should then sound like a Marshall!

 

[Joshabr1]

Yes. I didn't mean to imply anything bad about the board itself. Just most of the components on it.