The difference between a metalized polyester (Mallory 150) and a film/polyester (Sozo) at audio frequencies are just not going to be audible in top quality capacitors.  Both are great for Marshall circuits.

..Joe

I know this is almost a dead thread but I have to jump in.  I have been building amps for myself since '86 (a Mesa Mark III I used for 2 years on stage).  I am a for real electronics tech with a degree from my excellent local college in industrial electronics engineering.  We were the last class to cover tubes and because I was a guitarist before I started the course, when it came to anything amp related, I paid special attention.  So when I say this, I know what I'm talking about.

He knows what he is doing.

Thank you Nik.

..Joe L

Those Ampegs were very underrated when it came to power output. The power supply voltage was speced at 565vDC and with todays higher wall voltages, I would think it is close to 600v! I wouldn't be surprised that with fresh tubes your amp doesn't start to clip until 75-80 watts.  And a 4-10 cabinet can move a lot of air.

That must be one heavy MF!

Honestly, I'm not sure exactly what the power output is on the JTM45.  Looking at the design voltages with a tube rectifier, I would estimate between 35-40 watts at clipping.  But pushing it harder will make the HV sag due to the rectifier tube where that Ampeg will just keep getting louder!

I have no doubt that I have tinnitus and hearing loss due to running my V4 flat out with the channels bridged through a full stack of Marshall cabs.  I tried a half stack and toasted the voice coils of the greenbacks in 3 weeks.

..Joe L

I'm sure you can.  But please don't start with what is probably the most complicated amp that DIYers build.  Start with a well documented kit of a simple amp like a tweed Deluxe - http://www.tubedepot.com/tweeddeluxekit.html.  The Deluxe is a great sounding amp yet is simple enough to start learning the techniques you will need to build more complicated amps.

..Joe L

We played Ampeg V4s in the '70s through Marshall stacks so I am very familiar with the versatility of them. 

The distorted sound you are getting is easily matched by one of the older designs like the JTM45 and the '57 Fender Bassman.  But that loud, full clean sound of the Ampeg is hard to match.  Especially if you use a MV to cut down your stage volume.

The right pedal in front of a Hiwatt might also be a good compromise.  The pedal for the dirt sound and straight for the loud clean.

..Joe L

If it returns, see if you can control the loud hum with the Master volume.  If you can, the problem is in the preamp and most likely what you already fixed.

If the MV doesn't control the hum, I would highly suspect an output tube is failing and should be addressed immediately.

..Joe L

The Rhythm Clip is just that.  It connects a couple of diodes to ground which symmetrically clips (square wave) the waveform.  There is a capacitor across the diodes to help filter some of the harsh harmonics but it is still going to sound buzzy.  If you push the Master Volume enough to get the power amp to distort, it will smooth it out some and may be a sound you like.  But mostly it's just kind of gimmicky.

The Lead channel uses a more complicated network of diodes/LEDs that is much more musical sounding due to being asymmetrical.

..Joe L

The short answer is "yes".  Either method will work just fine long as you keep the grid wires a reasonable distance away from  the heater wires. 

I've built some clones that didn't even twist the wires and had no hum issues.  The Soldano SLO 100 and X88R 3 channel preamp are good examples.

My SLO clone from 99'.

http://webpages.charter.net/jlemoine/preamp.jpg



Grounding layout seems to be the most important hum producer with tube quality and output bias matching also a consideration.

And as far as the OP, get your wiring in position however you can with removable tape, hot glue, tie wraps and wooden splints, whatever and after a period of time, it will "set" into that position and you can remove the sticky stuff later.  Heat speeds up the process. 

I know, I know, you want to take those pretty pictures of the insides and show it off, but after a few years, you can remove every tie, strap, or whatever in a piece of electronics and not a single wire will move.

Welcome to the crowd.  I'm new also, but not to amp building.   First build was the "Bogus Boogie" Mark III clone that I built in '86.

I'm currently gutting my 4212 Marshall (2105 schematic)  which I had built what I think is the first SLO clone in order to shove a 2550/1987 switchable circuit into.  What I find interesting with the Ceriatone is the use of film capacitors in most of the positions the original Silver Jubilees used axial 100v ceramic capacitors.   I am going to use ceramics like the original at first and then wholesale change out to film caps to see how much it changes.  Ceramics usually have lower definition and different sounding highs compared to film or mica and seem to work well in Marshalls in the normal 1959/2203 circuits.

Anybody else played with caps in the Jubilee circuit?

BTW, best amp I've play though was an orginal 2550 with a 1/3 octave EQ in the effects loop to tweek the tone.   It made a huge difference.

..Joe L