Metropoulos Forum

I've got a Laney Pro-tube 30 combo that is in serious need of a makeover.

I'm thinking of making it into a separate head, then taking the speaker out and making a cab as well.

I was wondering - could the head be changed to a PTP board? Would one of your boards work?

A few people have put the boards in other models and brands. Anything that has room for a 11 5/8" x 3 1/8" board can be coverted. But there's sure to be a little drilling invloved for the mounting bolts.

George

VelvetGeorge wrote:Anything that has room for a 11 5/8" x 3 1/8" board can be coverted.

I would think that any amp could be converted to PTP, and probably be better off doing so. I guess it all depends on how many components are on the stock printed board, and how much work you're willing to do to switch over. As far as board size, I would also like to think that you could cut that board down if needed...right? What would you use to cut the boards?

Band saw would be best, I cut some of the red Fiberglass board with a hacksaw and it sucked butt. Enjoy the smell, too...or better yet, wear a mask, it stinks and can't be real healthy!!

Yeah, the smell sucks. And it's not healthy. I have my supplier cut it to size. And they complain about it every time. It smells up their whole shop.

George

So, to clarify, would installing a new board be a complete conversion to the other amp? In other words, if I put in the 50 watt lead board, would I necessarily need to change all of the components to the Marshall 50 watt lead? (Basically, to chuck most of the components presently in the amp?)

I'm asking because the Laney has a complement of four 12AX7s and two 6L6 tubes. Would I need to convert all parts over to the Marshall 50 watt lead specs? Would I be able to use any of the existing parts?

Scott

You could likely use all of the pots and switches, the transformers, tube sockets, any chassis mounted filter caps ect.

Don't forget too that the 50 watt board is a good platform to design and build your own circuit. You're not locked into the plexi specs.

George

I am not at the stage where I believe I could design my own circuit; I would like to stick with a tried and true design. The Plexi sounds good enough for me.

So how do I go about determining compatibility? Do I compare the schematics (something I'm not comfortable at)? I'm worried about plodding along in the dark being totally confused.

In that case you should start with the standard plexi circuit. From there we can make lots of suggestions for tweaking and learning the components and their function.

George

A Plexi sounds like a good place to start to me.

What is the first thing I should do? Measure the amp to see if the board will fit? Decide which board/amp to use? Would you suggest the Plexi 50 (and not the JTM 45, etc.)?

Just measured the board presently in the amp, and its approximately 12 3/4" by 3 1/2", so it appears the new board would fit no problem.

What was the control layout of the Laney? Was it a channel switcher or anything like that, or pretty straightforward one-channel setup?

Flames1950 wrote:What was the control layout of the Laney? Was it a channel switcher or anything like that, or pretty straightforward one-channel setup?

My understanding is that its not a true channel switching amp, but it does have a push-pull type volume knob which engages an extra stage of gain (also footswitchable).

The bass, mid and treble pots are also all push-pull types, boosting the frequency when engaged (knob pulled out).

It also has a wimpy reverb, which I could care less if its not retained in the project.

I have no problem gutting the thing and basically just using the chassis and a few components for a plexi project.

So using the standard 50-watt plexi board, you could use the volume push-pull to switch the .68uF gain boost cap on the second preamp tube in and out, use another push-pull to switch feedback resistor values for more or less power amp gain & distortion, and one to switch a bright cap in and out on the volume control, etc.
You could have a very versatile amp with the push-pull options there!!

Flames1950 wrote:So using the standard 50-watt plexi board, you could use the volume push-pull to switch the .68uF gain boost cap on the second preamp tube in and out, use another push-pull to switch feedback resistor values for more or less power amp gain & distortion, and one to switch a bright cap in and out on the volume control, etc.
You could have a very versatile amp with the push-pull options there!!

Very interesting! How difficult would it be to implement some of those suggestions? And what board would be the best one to use? The master volume or not?