Replacing Lego Block Signal Caps Vintage Modern

[frank9310]

I bought a JTM45 Reissue which had the same little Lego block capacitors as the ones I see on the VM circuit board. There were 5 x .022uF in the preamp stage and 3-4 x .1k caps just before hitting the KT66 output tubes. Anyway, the amp had a very ice picky top end so having read all the info about Sozo caps on the Metro forum I ordered a set and installed them. Well the amp became so dark then it sounded horrible. Then I replaced them again with Sprague Orange drops and Shazzam! the amp came to raging life like Trower's "Living Out of Time" sound. Very glassy top end with no ice picks just beautiful organic tone through a Vintage 30 cab. Incidentally, since many are talking about Trower using the VM he told a buddy of mine he still wasn't quite sold on it a few weeks ago in Indiana.
Also, hs favorite UK torung and recording amp is his own Robin Trower Signature amp made by Denns Cornell in the UK and it sports 6 x EL34 power tubes http://www.dc-developments.com/cornell_custom_RT100.htm

What's interesting here is that he plays his signature model live at the 60 watt setting to get better headroom. The VM is really more like a 70 watt amp than 100 from what I've read because the JTM45 is really 30 watts 55 watts peak while the JTM45/100 and VM is more like 70 watts RMS 120 watts peak. So he probably sees a similarity there in some ways as well as having the master volume. In addition, the his signature Cornell amps use Sprague Orange drop signal caps so if the VM had the ice picky grey Lego caps replaced with the orange drops, he'd probably be in tone heaven as it made a huge difference in improving the tone of my JTM45. Also, KT66s in the VM have just more of everything that an EL34 doesn't.

So I'm thinking of selling my JTM45 and getting a 2466 100 watt (70 watt) for more headroom and the first thing I'll replace is those crappy sounding Lego caps with some high quality Sprague orange drops. Now I haven't even played one yet but I know for certain it will sound better once those are replaced. The only thing I think I'll miss is the GZ34/5AR4 tube rectifier for it's sag and giving me that roaring Jimi-esque low end for songs like Wind Cries Mary, Hey Joe, etc. where the diode rectifier as used in the VM is supposed to have more edge along the lines of a JCM 800. So maybe I'll keep the 45 and have the VM in stereo like Trower uses for that "big" sound.

Also, to all you Trower fans, his new CD "What Lies Beneath" is a treasure trove of his best material to date and he tells inside how he records with 2 amps, one set clean and the other with Fuzz, etc. It's outta sight! My .02 cents... p.s. Thanks for having this cool forum!

[Bluesburst]

Hi Frank

This sounds very interesting, any chance of pictures of the components? My VM (2266 50 watt) is out of warranty now so I'm up for some experimentation!!!!

[frank9310]

Sure thing. It's the gray little blocks near the volume and other controls as seen on the circuit board pic http://marshallvintagemodern.com/viewto ... =28&t=2688

WARNING! Make sure to fully discharge amp first before touching anything inside or you can be killed dead, even if the amp is unplugged!

You just have to lift up the board, (unscrew board first) gently heat the solder pads and pull the lego blocks out and replace with the orange drops which you can buy in numerous places. It looks like here are 6 x .1k400v and 3 x .022uF400 near the control knobs. Zoom in on the pic and you can see the values right on them. Then, there are 3 more on the far right just under the 2 black buttons and I can't read those values but I would look closer with a magnifier and get hem and replace those 3 as well.

You can always pop them back in if you don't like the result but I can just about guaurantee you will. Most Marshall mod fanatics hate the lego caps and replace them. Replacing signal caps and the Output transformer are the 2 biggest things you can do to improve tone on any stock PCB type amp. However, I like to keep the Output transformer stock and only change that as a last resort but signal caps can transform an average amp into a top of the line boutique amp for about $15 of parts that you can get from Mouser.

[Bluesburst]

Thanks Frank

Looks like an experiment coming up in a few weeks when I get some other stuff off my plate...

[DeanM]

that would be really interesting to see what the results would be!! if any1 does this let us know!!

[frank9310]

I'm trying to get a 2466 now and warranty or not, that will be the first thing I do when I get it as I'm certain there will be a dramatic improvement. If you like the darker sound, then Sozos would be the ticket. For more of a Stevie Ray voice, go with Mallory 150s and for glassy, detailed mids and top end the Sprague Orange drops are the ticket.

[DeanM]

yeah but sozo's are fn expensive!! i would say maybe a mix of mallory and orange drops might work well!!

[frank9310]

They might be expensive but they don't always get you the sound you want. I first put those into my JTM45 Resissue and it made it so dark I couldn;t cut through the mix or even compete with a lousy Valvestate at an open stage recently. Once I yanked them out and put the orange drops in, it came back to life.

However, with 4 x KT66s and different Output Transformer voltages, tone stack, etc. they may sound better than how they sounded in my RI. Though I know you can't go wrong with Orange Drops regardless. I haven't tried the Mallroy 150s yet though I have a set to drop in at some point just to see. Gerald Weber the tube amp guru recommends putting them into all vintage amps but he's more from the Fender camp.

My theory on why they may not work well on PCB type boards is taken from Dennis Cornell who built Trower and Clapton's amps. He said something to the effect that with the copper traces running close together on PCB style boards that there are slight increases in capacitance which kills some of the highs" whihc is why he builds all his amps point to point. So if you put dark sounding Sozo "mustard style" caps in an amp that already has some rolled off highs due to the PCB traces running close together, it's going to sound too dark. Just like Jimi used those daisy chained 30-40 foot coiled cables that had increased capacitance which rolled off some of the highs on the super bright PTP Marshall Plexi's of the day. Cornell also used Orange Drops in Trower's and Clapton's amps.

[TonyC]

Very interesting reading!

Thanks for sharing all this info

[frank9310]

Right on!

With the right kind of tweaks, you can make a PCB style amp sound as good or better than most boutique amps costing several times as much. Don't always believe the hype you hear about better transformers because the power transformer makes absolutely zero difference in tone and the output transformer does only marginally unless you want to change power tube types and need different tap voltages, In some cases changing transformers ruins the original intended character of the amp where changing signal caps is something that doesn't really mess with the overall operation of the amp since they're in the tone stack part, as long as you make sure the tolerances are matched e.g. .022uF 400v you want to keep it the same, not like .022uF 600v, or .022 250v, etc. You can mess around with those all day as long as you don't damage the traces on the board. If you do, just sand it down a little with some sand paper to expose the copper trace and solder again!

[TonyC]

I've had my 2266 for two years now and to be honest I struggled in the beginning with what you describe here Frank, and even to some extent with the sonic issues that ClubAndCountry describes in the "Extensive component value changes" thread. More precisely the "hollow and glassy" thing with a bit too much ice pick. But during the two years I've played it I've experimented a lot with different preamp tube brands, and an enormous amount of different overdrive pedals to find a tighter and growlier tone, and to fill the "hole in the middle" so to speak. And I absolutely MUST run the master volume dimed or nearly dimed to get a full enough tone. An attenuator is a must for me. So I've managed to improve the situation a lot! But that also means I had to alter the basic tone of the 2266. I usually always have some kind of coloring OD pedal active between the guitar and the amp to achieve the tone I want. Clean boosts are not for me and this amp.

I play strats with low output single coils so I can "afford" having OD pedals running and even get it to clean up enough by turning the volume down on the guitar. I usually set it so that the overdrive from the pedal blends nicely with the preamp overdrive and gives a good amount of gain with the guitar volume at 10, though I usually live between 3 and 7.

Today I'm quite happy with my VM because it's really great in many other aspects. The way I can control it from my guitar I think is just lovely, and very few amps work that well. But there's always room for improvements and this thread really caught my attention. I'm not afraid of experimenting and always look for ways to improve things.

[DeanM]

Frank, you mention the sozo's were too dark? iv read before, and its even on the sozo website that they say those caps need to be broken in. they say that they only sound their best after a bit of use. somethin to do with the dialectric in those capacitors or something i think. could that be why you found them very dark sounding? or are sozo's just dark in general?

as far as pcbs, im not so sure. some say they wont sound as good but there are ALOT of amp builders that say nowadays that its all myth and just something botique amp builders say to sell their amps. a well designed pcb can be just as good as a well designed PTP layout. actually, even PTP can sound terrible and very noisy if not done properly. i think the hype about pcbs not bein as good is mainly down to the fact that alot of amps are mass produced and the quality isnt as good as it could be, rather than the fact a PCB is being used. i think that would be the reason, the standard of quality, rather than that PCBs cause tone loss. there is capacitance between the tracks but i remeber seein or reading somewhere someone either done tests or measurements or somethin and the results showed to be negligble. and plus if there is enough capacitance to cause loss of highs in a guitar amp then what about computers? they operate in the gigaherts....much much higher frequency ranges and they work fine. i know in a computer circuit you dont hear any of these signals but if a pcb had enough capacitance between tracks to attenuate highs in the audio range then that would destroy the signals or currupt them at processor frequencies.

and to go back to the point you make about the lego caps, orange drops and mallory probably will sound much better but the reason they are not used is cos marshalls, fenders etc are mass produced and to use such high quality components would cost marshall a fortune and drive their prices higher. botique builders have much less numbers to produce and so can get away with it more. but the downside is that at the much lower production quantity, to use PCBs would be too expensive so PTP is used even tho its more time consuming and requires man hours.

eh...im forgetting where im going with this!!

oh yeah!...

With the right kind of tweaks, you can make a PCB style amp sound as good or better than most boutique amps costing several times as much.

thats pretty much what im getting at. that some of the downfalls associated with PCBs are most likely to be the cheaper components used in mass production. so im sure the tweaks you speak of may be beneficial! so im interested to see how it turns out!!

i just recently built my first DIY handwired guitar amp!! and i used mallory and orange drops and also silver mica caps! so its also interesting to see what effect they have on a non-botique/production amp!

[frank9310]

Tony: I'd be curious to see what you think after swapping out the Legos for orange drops. What I remember most about the Legos is in a small room at bedroom levels I kept hearing this "tinky" treble type attack when I picked the strings. It would drive me insane. Then the mids and upper mids seemed like they were underneath the tinky sound and were not all that complex. The minute I swapped the orange drops, it was like all the tinky sound gone, mids and harmonics sprung to life and overall tonal balance was there in full bloom. I don't know why Marshall insists on putting those cheap Lego caps in such an important part of the sound which is the tone stack when caps aren't really an expensive thing to begin with, but to save a few cents here and there, they do it. It's up to the customers to teach manufacturers how to do things sometimes. LOL When they start seeing a larger percentage of sales going to the boutique builders, their eyes open a little wider and you start hearing about "hand wired" series, "Vintage Modern" etc. Althoughthe only thing vintage about the VM is the use of KT66 tubes.

Dean: Everythng you said is right and my amp tech says PCBs are superior in every way and gave me a list of reasons. PTP is much easier to swap things and you only have a few shots to muck around with a PCB before you potentially damage the trace lines but they're tough enough to swap out 2-3 times if you're careful and don't apply too much heat to the solder pads. The amount of solder used on the Legos is just a tiny dab so a quick heat up and they;re out but they do bend the leads so you kind of have to heat and straighten with some small needlenoses at the same time and grab them from teh top with some small pliers and try not to crack them if you want to hang on to them. I doubt if you'd ever want to put them back after hearing the difference.

About the Sozo's. I called and spoke to John Gaynor who makes them and told him the problem and he said some others have complained of that same problem with PCB type boards and he suggested I either put back the Legos or get something brighter. I did break them in for 2 days. He said if you leave the amp on even without tubes in it is good enough for about a day and you're good. They did have some nice lower mods but extremely dark on upper mids and highs at least on the JTM45. I don't know how they'd sound on a VM but I know I wouldn't even try them. He has another series of higher end Mustard caps and he said those are even darker so I had to pass there. This is the kind of glassy upper mid I'm getting withthe orange drops from a Robin Trower clip http://www.youtube.com/watch?v=CA1THYhQl10

[TonyC]

I'll probably do dome experiments later.

Caps are interesting stuff. Even in the guitar they have a great impact on the tone. Same values but different constructions make a big difference, especially how well the tone control works over its whole range.

[frank9310]

That's right. There's the one company who makes a 16 position cap pot that you can switch from 16 different cap values to go from super brigh to super dark and everything in between. I had one for a while in one of my Strats but yanked it because it takes up a tone control spot and I didn't like how you had to click it through each step to get to different values between songs.http://www.stellartone.com/Page.asp?NavID=50

When you talk about across the entire spectrum, that's one thing I did forget to mention in that when I talked about how dark the Sozo caps were, they did have a really fat, rounded lower mid that I loved but it was the mids and upper mids that were lacking. With the orange drops, you get the mids and upper mids but the lower mids aren't quite as fat as the Sozo's. So it was some small trade-off but I'll take the upper mids back over lows any day since the guitar is a midrange voiced instrument to begin with. If I monkeyed aorund long enough, I probably could put one or two Sozos back somewhere along the tone stack in the bass or mids section but they very well may be the same sections that killed the upper mids so not sure it will work. That IS the one nice thing about Point-to-point is you can change values and comonents as many times as you want where PCBs you have to be careful not to melt the trace lines. If you're an experimentor, a PTP type amp like a Metro kit etc, is probably the way to go.