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

[pjoliver182]

I agree; probably the El34s make it sound slightly squishy. It won't be the same spec Frank used but Tim is a master of modding! He'll have been able to recreate the AFD tone his own way.

[blacklabel]

This sound is the kemper, so if you like it, the real marshall will be amazing!
it means that the Kemper works

[BRMSlash]

Just tried a different reverb and added a little compression. Used the same recording as the previous clip.
http://sclk.co/s80r46

[BRMSlash]

Increased the 4th stage cathode to 1k2 to get a little more amp compression instead of using a software compressor on the recording. Tweaked the reverb plugin slightly too.
http://sclk.co/s80t3t

[bulldozer1984]

Increased the 4th stage cathode to 1k2 to get a little more amp compression instead of using a software compressor on the recording. Tweaked the reverb plugin slightly too.
http://sclk.co/s80t3t

I'd say that's a wrap. Nailed the tone man - anymore tweaking is purely because of the obsession.

The low end sounds about right. The top end sounds spot on and has the signature snarl. Sounds awesome man.

Too much reverb on the recording, but who cares.

[BRMSlash]

Thanks for the feedback. Yeah, I'm happy with the tone now. There's nothing more for me to tweak.

[antosimoni]

someone can explain me what does the 220pF over the 100k on #34 schem:
http://i1140.photobucket.com/albums/n57 ... 28c355.jpg
thanks

[herbvis]

It rolls off some highs. Can be used to control oscillatins or for slight tone shaping.

[herbvis]

It rolls off some highs. Can be used to control oscillations or for slight tone shaping.

[antosimoni]

thanks

may I ask also what does the 150k from gain pot to ground? it seem to me it interacts with the variable resistance of the pot changing it.. so with some setting of the pot it simulates a lower value pot (=warmer tone) while in others a higher one?

[Unique]

Because I'm OCD (like the rest of you!) I've been thinking about valves again (or 'tubes' for the non-brits).

#36 could have had EL34s or 6550s from the factory. I've used both...and KT88's actually. I've been using Shuguang EL34A for a while and really like them. I'm curious to try something that sounds as close as possible to the famous GE 6550A though. My understanding is that this particular 6550 variant could handle 42W dissipation rather than a conventional 30 or 35W (?) 6550. For this reason some folks like to use KT88's instead (42W).

I did a bit of Googling and found that TAD and Valve Art (and probably others) now produce a 6550A with 42W rating, and of course claim they are very similar in tone etc to the 'famous' GE 6550A used in Marshalls in the 70's...

...does anyone have any experience with these higher rated 6550's? I've only used Winged C's and cheap Chinese 6550's before myself.

The GE6550's are by far my favorite power tube. There's nothing like them. I've tried almost every current production 6550 out there and none of them even compare. The GE's have a 3-D like image to them, and great tonal balance. The Wing C's (SED), IMHO, don't even come close to the warm sound of the GE's. The SED Wing C's are kind of flat in the mid-range and don't break-up as good.

The only other tube I've heard that kind of has the same tonal balance, and distortion character of the GE's is the older 'coke' bottle Chinese 6550's. But these are crap tubes as far as quality goes and don't last very long. But these older Chinese 6550's do have a similar tonal balance and distortion character like that of the GE's, but lack the warmth, and 3-D like sound quality the GE's have.

Here's something else to think about, the GE6550's were what came in Marshalls back in day. Marshall relabeled them, Groove Tubes, Rivera, Raytheon, RCA, Sylvania also relabeled them, and so did many other tube companies. So if you bought an amp that used 6550's back in the 80's to early 90's it was highly likely it came with GE6550's in it. These tubes are built like tanks and last a long, long time. I think they had a 10,000 hour rating to them.

With that being said, I would bet almost anything that if #36 had 6550's in it, then more than likely it had GE6550's. From what my ears tell me, #34 definitely sounds like GE6550's on UYI. Last year I bought an '83 JCM800 2203 and put in a #34 mod and it sounds spot on with the GE6550's. They lend themselves well to that sound.

[Roe]

you mean 6550As?

[bill bokey]

How about what TAD claim is a remake of the GE 6550A ?
http://www.tubeampdoctor.com/en/shop_TA ... tched_2822
Anyone tried it ?

[Unique]

you mean 6550As?

GE6550 or 6550A, it's the same tube. I'm not sure if GE always had an "A" designation on them or not. I would have to look it up.

GE stopped making them sometime between '90-'92. Then some employees from the GE plant in Owensboro, KY created a company called "MPD" and produced the "GE6550 made by MPD To GE SPEC" 6550 version in the Owensboro plant when GE quit making them. MPD made them for a couple of years. I've never tried an MPD version of the tube, but have read that they weren't as durable as the original GE6550, but sounded pretty much the same.

I don't see why a name change would have made a difference in the quality of tube. Especially since they were being made by the same people, in the same plant, with the same machinery, to the same spec. Unless the specs were identical, but the recipe wasn't. More than likely this is probably just some bias by some people because it had "made by MPD To GE SPEC" on the tube.

[Unique]

How about what TAD claim is a remake of the GE 6550A ?
http://www.tubeampdoctor.com/en/shop_TA ... tched_2822
Anyone tried it ?

You know Shuguang bought all the tooling from the GE Kentucky plant to try and reproduce the GE6550. But they are nothing like them. The problem is GE never sold them the cathode recipe. Which is the key to the life of the tube, and it's sound.

I bought some and tried them, but they weren't even close to sounding like the original GE6550's. They had a lot of bass to them, and were much darker sounding. They lacked that 3-D like sound the GE's had, and the distortion character wasn't even close. Like I stated earlier, their original 'coke' bottle style 6550 was so much closer sounding to a GE than the tubes they make today with GE's old machinery.