12xxx Mod5 clip

[fhn_lopes]

I get you Andy, I can't imagine my life without my amp even though I don't play it every day, it feels safe to know it's there .... You'll be back on again soon mate, fo sho.

Maybe I get to build one too (like those new year's promises ) but if I ever get to do it, it's going to be the same thing that Mike is working on , the X3...

Hearing your clip again, man that phase is kicking major ass

[Tone Slinger]

Thanks Fernando, I do hope to get another amp together hopefully by the summer. I still have my Marshall 4/12

[echoplexi1974]

What were your Mod5 specs on this amp? Did you deviate at all from these specs?

1. Marshall 2203/2204
2. 12000 spec (MetroAmp's replica of the 68 plexi) low filtering
3. LAr/Mar PPIMV added
4. 220k resistor after the pre-PI MV
5. 100pF cap instead of a 470-500pF cap at the 470K/470K voltage divider
6. 25µF/25V across the 820 ohms cathode R of V2a
7. .1 coupling caps instead of .022's after the PI plates.
8. .0022uF V1b
9. 10K on V1a

Just curious.... Thanks!

[Tone Slinger]

Hi, thats the spec right there. The 25 uf cap over the 820 cathode resistor and the .1uf pi caps are the two places i deviated. I ended up with the 820 unbypassed and .022 pi couplers. In that 12xxx of mine the unbypassed 820 was tighter and more precise sounding without a bypass cap and with the .022 pi couplers the bottom end had more precision than with the .1uf's. Most of Rockstahs pcb reissue mods had this spec. I found that component brand/composition type in my amp really made a difference. Imo, certain areas of the circuit really respond to that.

[white noise]

Andy,

listened to your clip again, very nice sounding!

[Tone Slinger]

Thanks Terry, I really wish I had been able to hold on to that amp. Your Mod5 clips are much closer to Rockstahs sound than this one of mine was. You are the authority on the 'Rockstah Mod5 spec', seeing since you have Marks main 2 personal amps .The great thing about these 1959/1987 circuits.......one tiny switcharoo here or there and you've got a different tone variation. I miss that, and really need to get this 50 watt completed. I've been 'plexiless' for too long now

[white noise]

Thanks Terry, I really wish I had been able to hold on to that amp. Your Mod5 clips are much closer to Rockstahs sound than this one of mine was. You are the authority on the 'Rockstah Mod5 spec', seeing since you have Marks main 2 personal amps .The great thing about these 1959/1987 circuits.......one tiny switcharoo here or there and you've got a different tone variation. I miss that, and really need to get this 50 watt completed. I've been 'plexiless' for too long now

Sorry i haven't been on here alot the last few months. How far along are you on the 50 watter? What specs are you building?

[Tone Slinger]

I'm gonna get it up 'stock' first, say early '70's era (.0022 plate, '68 bypass on v2a, etc). Depending on what I'm hearing (and can learn to do),who knows where it will end up Since the selling of my 12xxx I've been going over in my mind all the things I DIDNT try, spec-wise on it. I've still only got about half the parts I need though.