So this JCM800 followed me home today…

[braintheory]

I concur with keeping the 6550's they are my favorite Marshall tube aside from beam forming element 6CA7's. 6550's are essentially big bottle 6L6's tonewise.

Aside from the KT-90's Braintheory as being like EL-34's KT-88's are often described as big bottle tubes that have a similar midrange emphasis like EL-34's which is supposedly why Marshall used them in the Marshall Majors and the Jimmy Page MSG amps. For new production KT-88's I personally like EH or Sovtek KT-88's over the JJ KT-88, the new Svetlana are ok but they are essentially Sovteks. The JJ's just have this compressed low end attack that I didn't care for but I know other people like them so YMMV.

As for boosts I guess it comes down if you want the amp to be classic rock, hard rock or metal. Dave's suggestions for the VFE are solid I would only add the Maxon ST=9 pro plus to that list for the heavier stuff. Other than that an SD-1 type of pedal or a Maxon OD808 or OD808+ are killer as well.

KT88’s to me sound more like a bigger KT77’s with that more hollow, round, less musical midrange I don’t enjoy as much. KT90’s (by EHX at least) actually have the EL34 midrange snarl and grind that no KT88’s have IME (not even my GEC’s nor Tesla’s). I far prefer to them to KT88’s, especially in something like a Marshall. KT90’s just didn’t exist yet at the time those amps were made sadly

6550’s to me sound like a bigger 5881, which I sometimes prefer to 6L6GC’s. There’s a certain crisp glassines/sparkle in 6L6GC’s that I don’t get with 6550’s or 5881’s. Either way for big bottle tubes I prefer generally 6550’s and KT90’s to KT88’s, but the GEC TT21 KT88’s are behemoths

 

[Philhouse]

I like the Boss OD-1 with my Marshall's lately. It's got an unusual freq range to my ear that works well compared to my SD1, TS9 etc.. Sounds good into my Wizzer Lead (unboosted) channel too

 

[Racerxrated]

Woah, yeah, 500V ain't playing around. Do you happen to know what month your amps were? I think mine is the latest low-voltage one I've heard of so far.

I don't; I've only had those higher voltage 82/83s so I assumed they all had those voltages. Your example is the first I've heard of a lower voltage version.

 

[7704A]

I don't; I've only had those higher voltage 82/83s so I assumed they all had those voltages. Your example is the first I've heard of a lower voltage version.

My transformers are stamped for January '82, and the choke for December '81 if that is worth anything.

 

[Bxlxaxkxe]

My transformers are stamped for January '82, and the choke for December '81 if that is worth anything.

Makes sense. Pretty sure the transition happened in early 82

 

[7704A]

Makes sense. Pretty sure the transition happened in early 82

That's what I've read too.

 

[glpg80]

KT88’s to me sound more like a bigger KT77’s with that more hollow, round, less musical midrange I don’t enjoy as much. KT90’s (by EHX at least) actually have the EL34 midrange snarl and grind that no KT88’s have IME (not even my GEC’s nor Tesla’s). I far prefer to them to KT88’s, especially in something like a Marshall. KT90’s just didn’t exist yet at the time those amps were made sadly

6550’s to me sound like a bigger 5881, which I sometimes prefer to 6L6GC’s. There’s a certain crisp glassines/sparkle in 6L6GC’s that I don’t get with 6550’s or 5881’s. Either way for big bottle tubes I prefer generally 6550’s and KT90’s to KT88’s, but the GEC TT21 KT88’s are behemoths

That hollow open character of KT88s are why I don’t like them either.

I’ll have to check out KT90s. Wrote them off ages ago from my general dislike for KT88.

 

[braintheory]

That hollow open character of KT88s are why I don’t like them either.

I’ll have to check out KT90s. Wrote them off ages ago from my general dislike for KT88.

It's weird because the older Yugo Ei and Chinese KT90's I have aren't quite as EL34-like in sound as the EHX's. The EHX's have that new-tube, more brittle flavor than those former 2 sounding more organic and vintage-y, but still prefer the EHX's for 34-like flavor. I heard KT90's draw more current than KT88's (not that I know this stuff lol) in case that matters for your purposes. I definitely enjoy them more than KT88's. I can say that much at least

 

[titanium777]

2204 50w vertical input from 1982. It’s all original and had 6550 tubes. I was surprised at how great it sounds. I was thinking it was going to have less gain than the EL34 model I had. I don’t think I would have been able to tell the difference. This one might be a little punchier in the bottom end. Not sure I should convert it to EL34s. Thoughts?

Also Looking for ideas on OD pedals. I have the following…
Boss Super Overdrive
Mythical OD
BB Pre
Benson Pre

I had a JCM800 a few years ago and ran a Friedman OD in the low input and that was fun, but it’s a very noisy pedal

View attachment 394108

Super cool Marshall 800

You can test EL34 vs 6550 relatively easily using alligator clips and a resistor to get the bias in the right range for the el34’s. Go back and forth for a couple days and see what speaks to you. Won’t be a life changing difference but it’s fun to experiment

Super Badass Marshall Jcm 800. Try adding a lynchmod in preamp section.

 

[BSRIAudio]

2204 50w vertical input from 1982. It’s all original and had 6550 tubes. I was surprised at how great it sounds. I was thinking it was going to have less gain than the EL34 model I had. I don’t think I would have been able to tell the difference. This one might be a little punchier in the bottom end. Not sure I should convert it to EL34s. Thoughts?

Also Looking for ideas on OD pedals. I have the following…
Boss Super Overdrive
Mythical OD
BB Pre
Benson Pre

I had a JCM800 a few years ago and ran a Friedman OD in the low input and that was fun, but it’s a very noisy pedal

View attachment 394108

Seeing the Pete Cage amp in the pic makes me wonder if you got this from Atomic. I think I walked right past you when you and the employee were looking for this head.

 

[Bxlxaxkxe]

Super cool Marshall 800

Super Badass Marshall Jcm 800. Try adding a lynchmod in preamp section.

I wasn’t crazy about the lynch mod personally. I’ve heard some people make killer tones with it though. Just a personal preference thing compared to using a pedal for the extra gain

 

[harddriver]

KT88’s to me sound more like a bigger KT77’s with that more hollow, round, less musical midrange I don’t enjoy as much. KT90’s (by EHX at least) actually have the EL34 midrange snarl and grind that no KT88’s have IME (not even my GEC’s nor Tesla’s). I far prefer to them to KT88’s, especially in something like a Marshall. KT90’s just didn’t exist yet at the time those amps were made sadly

6550’s to me sound like a bigger 5881, which I sometimes prefer to 6L6GC’s. There’s a certain crisp glassines/sparkle in 6L6GC’s that I don’t get with 6550’s or 5881’s. Either way for big bottle tubes I prefer generally 6550’s and KT90’s to KT88’s, but the GEC TT21 KT88’s are behemoths

I haven't heard a KT-90 in any of my amps but it sounds like an interesting big bottle tube to try in my 6550 amps sometime, but I'm just not an EL34 guy. I did read the description of the KT-90 and they all repeated the EL-34 attributes that you stated.

At least if the OP wants to hear what EL34's would sound like an pair of KT-90 would give him an idea without having to convert it.

I have a pair of GE6550A's sitting for my 84 Jose amp that I am assembling as we speak.

 

[harddriver]

I wasn’t crazy about the lynch mod personally. I’ve heard some people make killer tones with it though. Just a personal preference thing compared to using a pedal for the extra gain

Those have always seemed to have a bloated tubbiness to them in the clips that I have heard.

 

[braintheory]

I wasn’t crazy about the lynch mod personally. I’ve heard some people make killer tones with it though. Just a personal preference thing compared to using a pedal for the extra gain

Agreed. I had one too and much preferred just boosting Marshall’s with the Klon. I still haven’t really found much that can rival that for me

 

[braintheory]

Those have always seemed to have a bloated tubbiness to them in the clips that I have heard.

Yes, there is a low mid bloat they have, but still kind of tight in a way if that makes sense. The Soldano Hot Mod sounded so much better and more organic, raw tonally when compared to me, but ultimately nothing else I’ve tried yet really comes close to me for just boosting these amps with klons

 

[braintheory]

I haven't heard a KT-90 in any of my amps but it sounds like an interesting big bottle tube to try in my 6550 amps sometime, but I'm just not an EL34 guy. I did read the description of the KT-90 and they all repeated the EL-34 attributes that you stated.

At least if the OP wants to hear what EL34's would sound like an pair of KT-90 would give him an idea without having to convert it.

I have a pair of GE6550A's sitting for my 84 Jose amp that I am assembling as we speak.

Yeah maybe not then. The Yugo Ei and Chinese KT90’s didn’t sound as 34-like to me, but had a little bit of it there. GE 6550A’s are the best 6550’s IME, but not what I like to hear in Marshall’s. I feel I need 34’s in them to get that signature kerrang, midrange and upper midrange growl and basically all that other good stuff that make Marshall’s Marshall’s for me. 6550’s take me away from that. I also really don’t like 6CA7’s in them either for that reason, not even my Sylvania’s (which are not the absolute #1 USA 6CA7 brand IME anyway like the internet sometimes says). They can be great in Recto’s though with their more American voicing

 

[Killcrop]

I wasn’t crazy about the lynch mod personally. I’ve heard some people make killer tones with it though. Just a personal preference thing compared to using a pedal for the extra gain

Same. It was fine but I got better tones from pedals.

I got a chance to play the 800 with the band tonight. Got damn these Marshalls are designed to sit in the mix. R7 into BB pre into low input. I think I’m finally happy. After 30 plus years of chasing my tail.

 

[The~Kid]

Happy NAD.


Damn, that's what's up ^_^

 

[The~Kid]

I'd recommend going for two ODs and just stacking them a Klone and an SD1 or a Super Overdrive ain't bad if you got em around.


Can't go wrong there going into an a JCM800 I imagine

 

[Killcrop]

I'd recommend going for two ODs and just stacking them a Klone and an SD1 or a Super Overdrive ain't bad if you got em around.


Can't go wrong there going into an a JCM800 I imagine

Yeah I have all those. The Mythical OD works best but the BB isn't far behind. The SD-1 has its place but it's noisy. I love the flexibility of the low input on the JCM. It takes pedal so well you can get all kinds of different sounds. I am ordering an SLO plus pedal and see if I can't juice this thing with that.