Marshall 2203 REEEEEEEEEEE-work

[harddriver]

I think you will be happy with that filtering scheme. The rebuild looks like it is going well.

Here's what the EH6ca7's sounded like in my 69. This quad was biased at 50% dissipation at 125VAC and the amp is running on wall voltage no variac.


I think you will like them over EL34's if you have neer played them before. EL34's are a bit sluggish in the attack and too middy for my tastes but alot of people love them. I've found I am more of a 6L6 and 12H-30 guy after trying almost everything under the sun.

I think there was a reason Ed chose 6L6's fo the 5150 and 5153's.

[PLX]

I think you will be happy with that filtering scheme. The rebuild looks like it is going well.

Here's what the EH6ca7's sounded like in my 69. This quad was biased at 50% dissipation at 125VAC and the amp is running on wall voltage no variac.


I think you will like them over EL34's if you have neer played them before. EL34's are a bit sluggish in the attack and too middy for my tastes but alot of people love them. I've found I am more of a 6L6 and 12H-30 guy after trying almost everything under the sun.

I think there was a reason Ed chose 6L6's fo the 5150 and 5153's.

Yeah, I have another quad of EL-34's here, but I wanted to use the 6CA7's in the BE-50 clone. I figure I'll try them in this amp. If it's not to my taste I will just keep them as spares for the Ceriatone AH-50.

I ordered a 100µF/100µF filter cap for this project so I can use one section for the mains tap, and the other section for the PI tap.

That frees up the 32µF/32µF filter cap for me to try either 64µF or 32µF and see how that feels on the screens.

The can I have bolted inside the pre-amp end of the chassis will be the 50µF/50µF for the pre-amp taps.

[harddriver]

The 69 in the clip has the sotck 69 filtering scheme which I believe is as follows....

The typical '69 Marshall has 50uF on the mains, 50uF on the screens, 100uF on the phase inverter, 50uF on the second preamp node and 50uF on the first preamp node.

My 68 plexi which has 32uf/32uf preamp may have a little softer attack but there wasn't a whole lot of difference IMHO especially if you variac the amp down like I do with the 68 but at wall voltage that 69 was damn close to the 68. It was a great sounding amp but I had no attachment to it whatsover so I sold it in 2019.

At least you will be able to try the different values to see what you like.

[harddriver]

Here's an interesting read for you PLX.
http://forum.metropoulos.net/viewtopic.php?t=7133

[PLX]

The 69 in the clip has the sotck 69 filtering scheme which I believe is as follows....

The typical '69 Marshall has 50uF on the mains, 50uF on the screens, 100uF on the phase inverter, 50uF on the second preamp node and 50uF on the first preamp node.

My 68 plexi which has 32uf/32uf preamp may have a little softer attack but there wasn't a whole lot of difference IMHO especially if you variac the amp down like I do with the 68 but at wall voltage that 69 was damn close to the 68. It was a great sounding amp but I had no attachment to it whatsover so I sold it in 2019.

At least you will be able to try the different values to see what you like.

It had been so long ago that I did the last mod/rebuild on this amp that I forgot it was wired with 50µF on the mains reservoir tap. The amp was very quiet - no hiss, hum..

Since I have only three(3) cap can locations to work with (and I don't want to add any more to this chassis) I figured the best way to get the filtering I want is the 100µF/100µF, 50µF/50µF, and the 32µF/32µF arrangement.

If the amp feels stiff due to the higher filtering on the mains (I don't think it will) I can try adding a "sag" resistor following the rectifier diodes. Don't think that will be necessary, but we shall see.

[PLX]

Here's an interesting read for you PLX.
http://forum.metropoulos.net/viewtopic.php?t=7133

Mark's post threw me for a moment, but I realized he's talking about running some multi-section caps in series to halve the capacitance.

Rather than linking the two positive terminals with a jumper to run the sections in parallel to double capacitance:

[harddriver]

Here's a great comparison video of the EVH5150III 50 watters. One is 6L6 and one is the EL34, White is the 6l6 the Black is the EL34.

[PLX]

Here's a great comparison video of the EVH5150III 50 watters. One is 6L6 and one is the EL34, White is the 6l6 the Black is the EL34.

The 6L6 amp sounds better in that clip.

I have a Fender 6G2 "Princeton" amp that I have often thought about building into a higher gain design.

It has 6V6 output tubes, which are the "little brother" of the 6L6. According to Kevin O'Conner in "The Ultimate Tone" it is a great candidate for creamy distortion tones at lower volumes.

[harddriver]

One thing I use on my 2203 1x12 amp quite a bit is the Friedman SAT switch. I have it coming of the JCM800 master two IN5408's oriented asymmetrically through a toggle switch to ground. It gives me that chewy plexi feel with the 2203 circuit.

[PLX]

One thing I use on my 2203 1x12 amp quite a bit is the Friedman SAT switch. I have it coming of the JCM800 master two IN5408's oriented asymmetrically through a toggle switch to ground. It gives me that chewy plexi feel with the 2203 circuit.

A while back I was talking with FourT6and2 and he showed me a rotary clipping circuit he had done in one of his builds:

Alpha® "make-before-break" rotary switch.

Clippers are: 20v zeners, 18v zeners, MPSA06 transistors (wired in B-E-E-B configuration), 2N5401 transistors, and 5v zeners.





"decade box" test rig: