Siverface Dual Showman Mods/Upgrades, etc . . ?

[Geoff J]

Basically want a clean amp to A/B to or spike w/pedals, but am curious what can be done, such as eq tweaking, 2nd channel tweaking, etc . . .

I understand the JBL D-120 to be a good match

[benoit]

Basically want a clean amp to A/B to or spike w/pedals, but am curious what can be done, such as eq tweaking, 2nd channel tweaking, etc . . .

I understand the JBL D-120 to be a good match

What doesn't it do that you want it to?

[Geoff J]

Just wondering if there are any general mods/upgrades people do for certain things.
I have one on the way, so this is pre-emptive

[C Moore]

Maybe decide if there is one channel that you would like to keep the way it is. Then just start thinking about what other amps you like. You will be using the PI and output of the Showman. You are really free to do whatever you want. Maybe install a "Plexi" style preamp in the channel you abandon. Nothing has to be exact. No law says a plexi has to have EL34's. You can make it your own thing. Just start thinking about it and looking at schematics. Then you can get help with specifics. Don't forget about the early 1960's Brown and Blonde Fenders. You might want to consider one of those channels.
Good Luck

[Geoff J]

yeah, this should be fun. My bud who is doing the work said something about making the normal channel "marshally"

wanna try something skeezbo recommended insofar as "skylining" it

This was his suggestions for a twin, and since the DS is a twin in a head . . .

change 100k slope resistor to 150k
leave the .1 cap in place
change the .047 mid cap to .010

he also said something about the real Skyliner having a bigger treble cap (330P or 390p) and a 250k mid pot

[skeezbo]

Geoff,
I got these ideas from reading the Dumble forum here at Ampgarage, so credit goes to the real experts over there. I hope they find this thread; they will help you even more than I can, but let me add two more ideas:

The 250k mid pot is wired in an unusual way in Dumble's circuit; look at the layout and schematic and copy that. A 250k mid pot tacked in in place of Fender's 10k would probably not work, likely producing too much midrange and defeating the rest of the tone stack. After the other changes, I'll bet the preamp would sound just about as good with the stock mid pot wiring and the stock 10k pot. Try that first; if you need more mids you could increase the value to 25k.
I liked the sound of the stock 250p treble cap in my amp, so I didn't change that.

The other idea is more simple: I forgot to mention that many of these schematics show smaller cathode bypass caps, 4.7 or 5 microfarads rather than the 25 used in Fender preamps. If you swap to these lower values it will help trim the swamping ultra low bass.

I hope you have fun experimenting with this, I sure did!
Skeezbo

[Geoff J]

okay, so I just got the DS today, and I love the tone, stays clean at a high volume (Although the verdict is still out in a live band app)

So . . . I do understand the components on SF amps were not that good

So . . . . NOTWITHSTANDING the wild & wooly majical mystery mods, what parts should I replace straight up w/better components ?

[dobbhill]

I'd love to help, but I'm unsure of your goals....
Is there something wrong with the tone, or do you have a sound in your head you're striving for?
What pedals do you plan to put in front?

D

[Geoff J]

Goals: good high headroom cleans on the reverb side

JTM-45 or plexi ish on Ch 1 (marshall cleans)

Want to keep it simple and not add an extra gain stage, but use pedals for dirt

I am a Bebop/funk/hard rock/blues fusioner

I have the real tube & the tube driver, Barber direct drive, MJM Blues Devil

I like the above pedals for lead, but not necessarily for rhythm

looking at getting a wampler pinnacle 2 or tech 21 british for Hard Rock rhythm crunch once I can get Ch.1 marshallized.

Using a THD cab stock (vintage 30 & lead 80 cloned speakers - 140 W ??)

& sometimes a boogie 1-12 w/the EVM 12-L clone (I also have a spare EVM12-L - no cab)

AXES: Gibson Howard Roberts, Custom bucker strat
pickups are low impedance buckers (7.3 to 8.8 ) and a strat

I would like to get into dumble clean territory on ch.2 but get a dumblish facsimile lead tone w/a pedal on that channel, w/o having to add the gainstage on the amp.

I did see the skyline eq mod in one of the threads here, and that looked interesting. I hope that can achieve that "tight bottom end" inherent in dumbles and even Bruno's cowtipper 45



The problem I notice right now with the howard roberts, is that when i set the eq flat, and even while making adjustments, the bass seems boomy, but the tone can be somewhat thin and tinny at the same time, BUT NOT ENOUGH FOR ME TO DISLIKE THE AMP - just subtle tweaking it seems

I have a Merc Mag OT which was cloned for a 100W Fender Tonemaster & I was thinking abut dropping it in there to see what happens

Is there a problem with replacing the original parts with the higher quality components w/the same values , and then starting from there ?

[dobbhill]

Now maybe I can make suggestions:
I would try a Fender BF stack in one channel, and a Dumble-type in the other. The PI is somewhat designed around the 12at7, so I would leave it be until after I put in the channel preamp mods.

Then I would play the pedals (nice collection!!) through at that stage and are-assess.


I have a 50watter that I did that too, and also tried the CF Bassman/JTM tone stack, too, both pre's coupled with D-style OD...nice giggin' amp

Which chassis is it? I personally would not change out output x-former yet, depending upon which one you have.

only one dude's opinion...
D

[selloutrr]

if you want to clean up the circuit before you start modding the pajesus out of it. replace the input resistors with metal film and the ceramic caps with orange drops. ( you just dropped your noise floor considerably) assuming your filter caps are still good, now remove the death cap and add a grounded power cord. if your tubes are good you should now be safe and silent. from here get a couple decade boxes so you can alligator clip and tweak before you over solder and burn a part.

[Baxtercat]

Places to experiment:
How about changing some [or all] of the .1 caps on the board for .033 or .022, and/or making some coupling caps smaller too? That eliminates the extra boominess inherent originally. Cathode caps can be smaller too.

I redid a Showman not long ago and am having a blast with it.
[Here's a puff piece someone put up. Please ignore most of the hyperbole, since I don't really know what I'm talking about half the time!]

http://www.surfrock.org/guitar-bob-how- ... -more.html

[skeezbo]

Geoff-

Did you get the PMs I sent on the Tonemaster? They show up here in my "out" box, but not in my "sent" box. Anyway, I looked at the schematic, and it seems that a lot of the mods suggested here may already be on that amp. The most interesting to me is that the tone stack values seem to produce (in the Duncan tone stack simulator) results very similar to those I suggested in the Skyliner mod. And you don't seem to like it the Tonemaster much.

It makes sense that you like your silverface Dual Showman; it was designed to be what you need-a loud clean amp that happens to work great with pedals. By all means put in a modern AC cord as Selloutrr suggests, check the bias circuit and fix what else is wrong. Get Marshally on the channel one tone stack by changing both the .1 and .047 to .02, the treble cap from 250 to 500p. The slope resistor value probably should be lower, too, but I don't know what value to suggest.

Finally, even though many (including me) feel this is cheating, an outboard EQ pedal can help tame the woofiness, if you have it. Then play it and enjoy it!

Skeezbo

[Geoff J]

Skeez, thanks for looking out - but the DS Is just killing the TM right now !

Looks like an ebay situation

Thanks to you and the rest here, I will be mos def checking those swaps for the DS out

It came w/a new grounded AC cord !

To all of the rest, big, big thank yous !

Bob, the OD Twanger is KILLING = KILLING !

[Geoff J]

UPDATE:
We are currently BF'ing it (as much is it can) & marshalling ch 1

Will take pics and post

I ordered the stuff for the skyliner EQ for additional tweaking if need be

gonna be pulling out the Merc mag trannie I used for the Tonemaster and putting it in there as well just to see what happens