1976 Marshall Super Bass

[Don Corleone]

I have the chance to buy a 1976 Marshall Super Bass for just over £1000 GBP.

I have heard that this era Super Bass essentially has the same electrics as the 1967 Super Lead - Is this correct?

[indeedido]

That is what I've always heard, it has the same circuit, just a different cap for the bass frequencies. Change that and you have a super lead

[Don Corleone]

That is what I've always heard, it has the same circuit, just a different cap for the bass frequencies. Change that and you have a super lead

How big a job is it to change the caps?

[indeedido]

Depending on your skills, not a tough change. A local tech may charge $50, it's pretty basic.

Here is what I found doing a quick search, I'm sure there are more details out there if you search for them.



what most people don't know about the early Super Bass (pre jcm800) is the circuit is identical to the 1967 Marshall Super Lead, bar the bright cap across the volume pot.

Now when u dime a Marshall Super Lead to 10 the bright cap it bypassed so the circuit difference between a 67 super lead and a super bass on 10 is 0%.

Malcom Young uses a 69/70 Super Bass to great effect in Ac/Dc.

anyway more to the point, u hear people talk about that great thick plexi tone? well this is it ladies and gents. pick up a Super Bass from 69 to 73 and u've essentially got yourself a 67 Plexi Super Lead a whole lot cheaper

[indeedido]

Here's something you'll find interesting, scroll down to the metal face section.

http://blueguitar.org/new/schem/mars...ll_layouts.pdf

[jhale667]

I've heard the same thing about that circuit. If I had the liquid cash, I'd probably drop for it, yeah.
Another resource you should check out is the Metro Amp forum. You'll most likely be able to find a thread that will tell you the exact values for the components you need to switch over, and while you're there you can buy said parts, too!

MetroAmp.com Forum • Index page

[Don Corleone]

Thanks

I went back to the shop today. I know the owner so he's agreed to lone me the amp over the weekend so I can give it a work out with my own stuff.

If I like it, I buy it; that's the agreement

[Nitro Express]

I have the chance to buy a 1976 Marshall Super Bass for just over £1000 GBP.

I have heard that this era Super Bass essentially has the same electrics as the 1967 Super Lead - Is this correct?

I don't know about the 1976 version but there was only one resistor value difference in the late 60's versions. I would believe the 1976 model would have a circuit board as opposed to a bread board and point to point. Also the power tubes could be different. What really makes an old Marshall good is the transformers and the power tubes. Preamp values matter as well but it's really the power amp stage that matters the most. The right power tubes, transformer, and speaker cab is more than half the deal.

[Nitro Express]

How big a job is it to change the caps?

It requires a beginers level of soldering. It's no big deal. The important thing to realize is the filter capacitors can store enough charge to kill you! You bleed the charge off to the chassis ground, cut out the capacitor or resistor you want to change, and then solder in the new one. One nice thing about old Marshalls is the resistors and capacitors are easier to replace than the newer circuit board based amps.

Other than potentially electrocuting yourself because you didn't bleed of the charge in the filter capacitors first, it's a fairly simple job. A lot easier than replacing a jack or pot actually.

[BlimpyCHIMP™]

Other than potentially electrocuting yourself because you didn't bleed of the charge in the filter capacitors first, it's a fairly simple job.

I got zoinked by touching the big blue cans before, the filter caps, and survived. It's a pretty big jolt though.

Also keep in mind that even though it's a simple change of parts for a beginner, the layout is a roadmap of confusion for a ook beginner.

I would stick pieces of masking tape down on each connection you lift, and when the parts are removed, tape a masking tape tab on each leg with the corresponding numbers:

circuit board connection #1=resistor leg #1
circuit board connection #2=resistor leg #2

- and so on.

This is a 76, not a plexi so you're dealing with copper tracings on a fiberglas board, not a point-to-point turret holes layout. It is possible if you overheat the trace where you lift a part off it, that the tracing can lift off.

Marshall boards are etched from really thick copper layers so they're not like computer boards and are pretty durable to heat, but they can lift off. The way this happens usually is from someone using a shitty soldering iron say, 15 watts and holding the tip forever waiting for the connection to melt, which never happens, but is just enough heat to detach the pcb tracing from the fiberglas.

Try to use a 40 watt, at the least a 25 watt. And do not use that RoSH solder, that's stuff is ookook shit. It has too high a melting point and has too much tin in it requiring a much hotter iron, you'll hate it.

Use regular 60-40 rosincore solder and you'll do quick and fine work of it, when you fix the tone stack to plexi spec. It's pretty simple if you can just buy the values preselected and put them in yourself.

[BlimpyCHIMP™]

btw I personally do not believe all that bullshit argument "point-to-point" vs pcb

[ELVIS]

Neither do I, but all Marshall non-master volume amps from the 60's and 70's all sound different...

I have three and I have owned many more...none have sounded the same...

I have a '69 Super Bass that has never been modded and I never would. Most number one inputs on most Super Leads that I have heard are usually way too bright and brittle for my liking...

The Super Bass has a very nice warmth to it that suits guitar just fine. So, i'd be playing with that '76 and seing how I like it before making a snap decision to change anything...

[BlimpyCHIMP™]

The biggest difference between the Superlead and the Superbass to me, is the lettering on the back chassis panel because sonically I agree most Superleads are too shrill anyways.

On my old 100's I had the mids about 6 to 8 everything else about 10 except vol.

On the Superbass everything 10 sounds the same. Same distortion, same gain, in fact not enough to argue modding to a Superlead 100 board spec in my opinion.

But from what I've read, I wouldn't mind playing with a few values others have recommended add certain flavor to the Superbass because vintage people HATE that it's labeled a bass amp, therefore sells for alot less than a Superlead and to my mind not worthy of keeping to stock specs.

[ELVIS]

I think "Super Bass" is cool...

I seek them out more than Super Leads...

[Nitro Express]

btw I personally do not believe all that bullshit argument "point-to-point" vs pcb

The advantage of point to point is it's easier to change the circuit layout. Doing so on pcb requires sanding out links and putting in jumpers. As far as sound goes, pcb's are going to be more consistant because the signal routing is on the board.

What point to point has going for it is it's easier for an amature to build a circuit from scratch and modify it. It's the hand built method of building circuits. Circuit boards come into play if you are mass producing.

[Nitro Express]

I got zoinked by touching the big blue cans before, the filter caps, and survived. It's a pretty big jolt though.

Also keep in mind that even though it's a simple change of parts for a beginner, the layout is a roadmap of confusion for a ook beginner.

I would stick pieces of masking tape down on each connection you lift, and when the parts are removed, tape a masking tape tab on each leg with the corresponding numbers:

circuit board connection #1=resistor leg #1
circuit board connection #2=resistor leg #2

- and so on.

This is a 76, not a plexi so you're dealing with copper tracings on a fiberglas board, not a point-to-point turret holes layout. It is possible if you overheat the trace where you lift a part off it, that the tracing can lift off.

Marshall boards are etched from really thick copper layers so they're not like computer boards and are pretty durable to heat, but they can lift off. The way this happens usually is from someone using a shitty soldering iron say, 15 watts and holding the tip forever waiting for the connection to melt, which never happens, but is just enough heat to detach the pcb tracing from the fiberglas.

Try to use a 40 watt, at the least a 25 watt. And do not use that RoSH solder, that's stuff is ookook shit. It has too high a melting point and has too much tin in it requiring a much hotter iron, you'll hate it.

Use regular 60-40 rosincore solder and you'll do quick and fine work of it, when you fix the tone stack to plexi spec. It's pretty simple if you can just buy the values preselected and put them in yourself.

I was bleeding caps off a Fender Twin using a screwdriver and it welded the screw driver to the chassis!

[BlimpyCHIMP™]

HAHAHA done that..

superbass pictures by ammscray - Photobucket

Enjoy some pics of a 74 superbass someone has for sale on Craigslist Los Angeles section.. $1000

[ELVIS]

Bleeding filter caps is a dangerous operation...

These caps can remember a charge after bleeding and still come back and kill you...

My dad was an electronics technician in the military and he always said to clip two connectors to a meter, stand back, power it on and read your values...

I go by the Tube Amp Book and clip my negative lead and probe the positive with one hand behind my back...

These amps can kill with sometimes more than 600 volt plate voltage...

[BlimpyCHIMP™]

These caps can remember a charge after bleeding and still come back and kill you...

Sounds like my ex-galpal!

[ELVIS]

LMAO!

[Don Corleone]

The Super Bass has a very nice warmth to it that suits guitar just fine. So, i'd be playing with that '76 and seing how I like it before making a snap decision to change anything...

I've got it at here at home with me now (on loan for the weekend to see what I think). I've got to admit, I really like and I've already made my mind up to buy.

As for modding it, I think I'm just going to keep it as it is. I just love the tone that I'm getting from it.

[ELVIS]

After you purchase it, swap the preamp tubes for Chinese gen 9 tubes and put whatever you want in the power amp section or leave the power tubes alone if they are less than five years old and work...

Most people don't realize that the first tube closest to the input has the biggest effect on tone. Get one Chinese tube and put it in that slot and the amp will be really smooth and creamy. Not blairy and shrill, but most Super Bass amps don't have that problem...