S.I.R. 100W SuperLead Schematic pt. II

[lespaul6]

Which scheme are you using? It's possible to do #34 with the master on 2 and the gain on 7 or 8, without a PPIMV. It's hard to give out much info, because too many folks want to start amp companies with other people's work. The Fender / Marshall / Jose trend continues, I guess. There's a guy who sells mostly other people's and company's mods, while pretending to be an expert authority. Sure, he changes a cap or two, sometimes throws a snubber cap here or there. Hard to believe people eat this sort of thing up.

I agree... well Ive tried the 34 mod done by RJS and sold it, didnt sound good, too too bright. And I like bright. But this was just dumb and a depth knob was done to try and compensate, which brings in a bunch of other issues with the tone. Then I had friedman do his AFD mod and I didnt care for that either, didnt sound right. I see most other diy guys use a ppimv like the ceriatone afd, again, to most likely tame the high end... but the mod is not right.
I think the "issue" is finding a recipe that will allow you to use that .1uf cap without it overwhelming everything else and losing a balance to the eq/tone. Maybe I just need to do the 36 mod to fill out the eq and round off the strident nature of the 34?

[CoffeeTones]

Nah, the PPIMV just makes the #34 more usable and easier to stay in front of. That mod is unbearably bright and thin until you have the gain cranked way up. Built according to the Santiago schematic, that is just what the amp is when it's in the sweet spot.

A great, accurate #36 sound can be had without the added stage and the issues that come with that added tube.

On another note, I've been holding off, but will now say that everyone including myself, has been doing the 4 stage, #36 mod wrong. If that mod is done right, the amp will make the guitar feel unbelievable with an amp this bright and tight.

[rockgod212]

Nah, the PPIMV just makes the #34 more usable and easier to stay in front of. That mod is unbearably bright and thin until you have the gain cranked way up. Built according to the Santiago schematic, that is just what the amp is when it's in the sweet spot.

A great, accurate #36 sound can be had without the added stage and the issues that come with that added tube.

On another note, I've been holding off, but will now say that everyone including myself, has been doing the 4 stage, #36 mod wrong. If that mod is done right, the amp will make the guitar feel unbelievable with an amp this bright and tight.

so we have been doing the mod wrong? do tell in what ways. could it be that the xtra stage went before the 1st stage on the input side like a plexi xtra stage mod? could the 36 be more like a mick mars plexi amp mod to where there are 2 2.7k/.68 stages with the normal channel blended in?

a can of worms has been opened, lol.....

[BRMSlash]

I've changed spec again, back to a more typical arrangement. Also managed to get rid of the ringing/clanging sound on the intro of 'welcome to the jungle' by removing the MTK1813's in both my guitar & amp. Now using 225p in the guitar & MKT368 100n as cathode bypass cap. I've moved house recently so haven't got my recording gear set up yet.

1st stage: 33k, hot shield, 2k7/680n, 100k/220p, 22n, 2n2/1M pot, 1n/470k/150k.
2nd stage: 10k/100n, 100k/470p, 22n, 1M pot
3rd stage: 2k7, 100k, 22n, 470p/470k/470k
4th stage: 820R/470n

I still might bump up the 15k PI tail resistor to get a bit more compression.

[CoffeeTones]

I've changed spec again, back to a more typical arrangement. Also managed to get rid of the ringing/clanging sound on the intro of 'welcome to the jungle' by removing the MTK1813's in both my guitar & amp. Now using 225p in the guitar & MKT368 100n as cathode bypass cap. I've moved house recently so haven't got my recording gear set up yet.

1st stage: 33k, hot shield, 2k7/680n, 100k/220p, 22n, 2n2/1M pot, 1n/470k/150k.
2nd stage: 10k/100n, 100k/470p, 22n, 1M pot
3rd stage: 2k7, 100k, 22n, 470p/470k/470k
4th stage: 820R/470n

I still might bump up the 15k PI tail resistor to get a bit more compression.

That likely sounds nice. I built a very similar spec. I accidently put a 180k plate resistor on stage 2 (10k//.1uF). Yeah, I didn't have my glasses on, and the color bands are kind of similar, LOL. The 180k was bypassed with a 250pF, X5F ceramic that measured at about 230pF, no bypass on stage 1 plate. I think you should give that a go and see what you think.

[CoffeeTones]

so we have been doing the mod wrong? do tell in what ways. could it be that the xtra stage went before the 1st stage on the input side like a plexi xtra stage mod? could the 36 be more like a mick mars plexi amp mod to where there are 2 2.7k/.68 stages with the normal channel blended in?

a can of worms has been opened, lol.....

Man, I'd like to share the details, but I don't want this mod in someone else's line up. I want it to be clear that I am not referring to anyone who has been a participant / contributor in this topic for a long period of time. Not that I'm aware of anyway.

[Unique]

On another note, I've been holding off, but will now say that everyone including myself, has been doing the 4 stage, #36 mod wrong. If that mod is done right, the amp will make the guitar feel unbelievable with an amp this bright and tight.

I have been hearing a lot of mice on tread mills since this comment was made. You might have just took this thread on a new turn...

[jarrodthebobo]

On another note, I've been holding off, but will now say that everyone including myself, has been doing the 4 stage, #36 mod wrong. If that mod is done right, the amp will make the guitar feel unbelievable with an amp this bright and tight.

I have been hearing a lot of mice on tread mills since this comment was made. You might have just took this thread on a new turn...

Has anyone tried some sort of Jose style 3 + 1 stager but using lower value cathode bypass caps? With how prolific those Jose mods are and how it seems like most marshall mods straight up copy the basic vision of those circuits, I wouldn't be too shocked if the #39/36 shared its DNA with them.

I got a preamp project on my bench right now with 3 12ax7s; with a Jose style setup with two preamp knobs instead of the single... "pseudo-PI" stage and a cathode follower output... maybe I'll start screwing around with that and see where it ends up!

[lespaul6]

Using this schem attached, I left the amp a stock 2203 and just did the .1uf on the 10k, .68 on the 820r, and the 470pf on the 100k to mimic the hot shield... sounds pretty good. I left the stock peaker set up 470k/470pf and 1000pf bright cap.

I did not put a 150k on the gain pot from wiper to ground... tried it and it sounded like crap, thin and shrieking.

Is it possible that this mod can really come down to just three or four parts?

[CoffeeTones]

Which schem? Seems you built a #34 with no 150k to ground and no 22k PI tail. #34 sounds a lot like #36, but not in some respects. #34 with 150k doesn't get right until you have the gain nearly dimed. That helps with the brightness and thinning some. Below that is pretty bad IMO. Not much difference between .47 and .68uF over the 820r. #34 is more tame with 10k PI tail. #34 needs a .47 to .68uF presence, .1uF is too wild for an extremely bright preamp.

[lespaul6]

coffee ... I'm trying to insert an image on the board from Imgur and not having any luck

heres a link: https://img1.wsimg.com/blobby/go/525b4e ... 5343342473

[CoffeeTones]

Yeah, Metro doesn't handle attachments well. Too much treble roll off for me in that scheme. Not that you used all of it, but all those plate snubbers and cap to ground from coupler usually sounds pretty flat to me. It has a bass boost in the NFB path, but a large value presence cap will eliminate the need for an NFB bass boost and most treble snubbing caps in preamp. If an amp needs all of those boost / snubber components, you don't want to try a 22k PI tail. That PI tail is a big part of #34's tone, not that #34 tone is your goal. I know #36 can be mimicked really well without a 4th stage.

[lespaul6]

totally agree with you.. been going back and forth all day with alligator clips....here's what I have now.

.1uf over 10k
.68 over 820r
470pf over 100k (resistor right next to 820r) not the one on the v2 socket pins.

everything else stock

thanks for your replies

[snakepit86]

On another note, I've been holding off, but will now say that everyone including myself, has been doing the 4 stage, #36 mod wrong. If that mod is done right, the amp will make the guitar feel unbelievable with an amp this bright and tight.

I have been hearing a lot of mice on tread mills since this comment was made. You might have just took this thread on a new turn...

So, are we gonna make a new tread?

[Unique]

I'm beginning to think that coffee was just trying to give this thread a little life with some click bait. It reminds me of that commercial; "Your doing it wrong!"

So, the tread rolls on...