Metropoulos Forum

I've considered trying 6550's in my plexi reissue for a long time - just never had $200+ to experiment - always had more important gear needs.

I recently bought a twin reverb reissue and have found that I much prefer the cleans on that to my plexi. Mainly on the fender the EQ is more responsive and I can get a darker, tighter low end, full sound, with better note separation. Lately I've really been getting into modern jazz guys like Kurt Rosenwinkel and Jonathan Kreisberg. I've always loved the hell out of my plexi so its strange feeling like its not hitting the spot like the twin is.

The question is if I switch to 6550's in it, can I expect it to behave more like the twin reverb? Or, is the marshall, just from a circuit standpoint, voiced a certain way and it will always be more focused on the mids and grind. I want it to be warm, tight, clear and have great headroom. Its pretty close to that but just not quite as good as the Fender for this style. What do you guys think?

I used to have a 1976 Marshall 50-watt 2x12 combo w/ 4-inputs (standard circuit- Lead & Bass, high & low) which had 6550's. It had a beautiful clean sound, but different from a Fender Twin Reverb. It was a nice sound. I was an idiot for ever getting rid of it...

But Eric Johnson uncompromisingly, uses Marshall Lead amps AND Fender Twin Reverbs, so what's that tell you?

As Leo went through design changes from the tweed and brown face amps he was focused on getting more clean headroom. The Blackface amps were a step in that direction, utilizing a mid-scoop circuit. 6550's may get you more clean headroom but will not get you into "Twin Reverb clean" territory.

Yeah, I mean I'm not looking for those very classic spanky fender cleans - I actually set the twin with the treble at about 2.5, mids about 6 and bass about 6 or 7 - then I run my AC booster into it so I can get a super thick jazzy tone on my neck pickup with the tone knob rolled back a little and a thick pick. When I plug into the plexi the tone just doesnt have enough focus, or the same tight low end.

If its truly just the marshall circuit itself - would a Hiwatt do the trick better? The other thing is, what would 6L6's actually sound like? In the plexi that is.

basile865 wrote:If its truly just the marshall circuit itself - would a Hiwatt do the trick better? The other thing is, what would 6L6's actually sound like? In the plexi that is.

My buddy, also a forum member here (jbzoso2002) tried 5881's in his jtm45 and removed them because they sounded, in his words, "too Fendery". Might be something to look into.

thanks for the suggestion man. I did look them up on here under that tube description thread and the 5881s have apparently less output and low headroom so that's a no go for me. A friend said kt88s are warmer and he much prefers them over 6550s. I just want a tighter low end with high headroom and better clarity. I'm thinking its between those two and maybe the 6ca7.

Hi Rob, I agree with the 'circuit' itself being of more importance than the power tubes. Use the Music Man HD-130 as a example (I finally got another, I LOVE these amps !) I've heard el-34's and 6ca7's in them but the sound is very much the same.

I think that in a Marshall you would hear what was described earlier here, which is you could get a tighter, firmer tone by using 6550's or 6ca7's. More glassy sounding with the mids being less emphasized.

I think you should try the EH 6ca7's. These are exact copies (maybe not quite )of the old Sylvania/Phillips 'big bottle' 6ca7.

I say give them a try, but I agree that there is only so much you can do, since the Marshall has more gain in its preamp and less plate voltage in the output section (as compared to the Fender, or Music Man for that matter).

Most Jazzer's and other less 'Rock'n'Roll' type players dislike and disregard Marshalls for this. Marshalls have that certain charector which is TOO agressive for many styles. I like what Al Dimeola did with a Marshall/Les Paul on his '76-'78 solo albums.

Cool. Yeah my buddy who owned the Music Man HD130 had to move out of state so access to that amp is gone which is why I finally got my own combo amp - the twin reverb. My tastes have since changed a little as well. The Band of Gypsies vibe will always be an important part of my sound, but Jazz is becoming very important as well. I'll never be a straight ahead Jazz guy, but I'm looking to create a bit of a hybrid. Blues/Rock combined with Jazz. I guess its somewhat of an unpopular thing to use a plexi to fill that need which is probably why many don't really prefer the 6550. The only way to know is to do it I think at this point. I've posed this same question over on the Eric Johnson forums to Eric himself....we'll see if he ever gets around to answering it. Although then again somebody else here had mentioned this is the very reason he uses both a plexi and a twin reverb Not all of us are in the position to be pulling around those two to gigs haha. Well thanks for the input guys

basile865 wrote:Cool. Yeah my buddy who owned the Music Man HD130 had to move out of state so access to that amp is gone which is why I finally got my own combo amp - the twin reverb. My tastes have since changed a little as well. The Band of Gypsies vibe will always be an important part of my sound, but Jazz is becoming very important as well. I'll never be a straight ahead Jazz guy, but I'm looking to create a bit of a hybrid. Blues/Rock combined with Jazz. I guess its somewhat of an unpopular thing to use a plexi to fill that need which is probably why many don't really prefer the 6550. The only way to know is to do it I think at this point. I've posed this same question over on the Eric Johnson forums to Eric himself....we'll see if he ever gets around to answering it. Although then again somebody else here had mentioned this is the very reason he uses both a plexi and a twin reverb Not all of us are in the position to be pulling around those two to gigs haha. Well thanks for the input guys

Have you thought about modding the first channel of your Twin with more Marshallesque mid emphasis? Then just use an A/B box, to switch between the two.

That is a great idea, and isnt very hard to perform. Gerald Weber has a diagram layout as to how to do this. That way, you could be very close to having 'THE BEST OF BOTH WORLDS'. As far as 'new' 6l6 tubes are concerned (your Fender probably has EH ?) the JJ's are real good. I have a friend who has them in a Peavey xxx and they give a great detailed tone as compared to what was originally in it (I think they were EH ?) Here again, no 'NEW' tube company has the BEST example of every tube type. Some prefer 'this' company over 'that' company when it comes to el-34's and others like another company's 6l6 over another's.

Its tempting but I actually love the twin for what it is, and I'm just trying to make my marshall slightly more fendery. As for the tubes in the twin its fender labeled Groove Tubes. It needs a retube - I bought the amp used but right now itll be a little while of paying off the amp on my credit card haha. *sigh* I appreciate the input though guys. Right now I'm just hoping that somehow the 6550 tube would make the natural EQ of the plexi a little more fendery. I think its just an experiment I'll have to take when I get the spare cash sometime. The funny thing is I havent used the plexi for a while now, but I'm too damn attached to it to get rid of it. I have friends who buy and sell gear like it was their job just going through and learning as much as they can - me on the other hand I work so hard and save for so long to get the gear that when I finally have it I'm attached to it and fear if I sell it I'll be the guy saying "I used to have such and such amp 10 years ago......I wish I never sold it" I've been there with guitars!

Before you do any of that, may I ask what type of caps you have in the tone stack?
I had sozos in mine, changed the bass .022 cap to a CDE DME 1KV cap and it make it a LOT spankier.
So much so that I turn the volume down on my strat and can play really convincing SRV stuff. Before it was pretty muddy.
If you can get your hands on some of these, try that and I think you'll like the results.

Well it seems that 'tweaking' and 'tinkering' is something that you will probably end up doing, since stock available gear misses the mark of certain practicle parameters.

What are you now Rob, 24 or 25 ? You were/are a player first, with 'teching' interest coming more and more as of late (not trying to say I know any of this as a fact ).

I say that slight modifications is no big deal, and could get you closer to where you want to be. You got a 50 watt DSL, a reissue Super Lead and a Fender Twin '65 right. Many mods are being done to each of these particular amps, and can be 'reversed' very easily and original selling value can be retained.

Transformer upgrades really make the DSL's come to life, The same for the SL, but MUCH more can be done to it, since it's so simple a circuit. LOT'S of people are tweaking one channel in the Super Reverbs to get more gain, basically calling it a 'british' channel. Just a few component value's changed.

I think the brand of caps is important as well, liked mentioned by steadyeddie. I would say you are on the right track as far as simply trying power tube types first.

yeah 25 now. I think I fear modding in a certain way - I'll apply it to a car example. I used to be into modding cars (eventually gave it up just because it was too expensive) but I worked on mine and friends cars. I found for every mod we did, lets say cold air induction, changing gear ratios in the rear end, etc. wherever you gained performance, you lost it somewhere else. If you gained low end torque you might lose power up top or lose gas milage or something like that. I like what the amps are in stock form overall - I dont want to mod them into something totally different - I just want to *enhance* tonality if I change any of the components, and shift the voicing slightly on the plexi. I'm hoping the tube swap might be something that will voice the plexi slightly more like the twin reverb. I just want to keep strong headroom, and tighten the low end. I'm not really trying to get the classic spanky fender sound because I don't really use that quality on the fender twin reverb itself - I actually keep the treble only between 2 and 3.

Its kind of a weird analogy - it might make sense or it might not - but, its almost like playing on the twin reverb is like being able to think clearly - like you're fed and well rested, where as on the plexi its like your thoughts are slightly cloudier - you're a little tired and hungry - cant think as clearly. if that makes sense at all.....