Help with some Marshall questions, please?

[diode breath]

Evenin', everyone;

I have an old SF Princeton chassis into which I would like to build an 18-watt Marshall circuit. Plan on using the original PS, power and o/p transformers, two 6V6s. Currently have two 9-pin sockets in the chassis, have no qualms about putting in a third (how much can you destroy the value of a SF Princeton?)

Does anyone have a decent copy of a Marshall Model 1958 schematic and chassis layout that they can send via email, please? I was going to get a turret-style board for the 18-watt TMB version, no tremolo, and add a prescence control. Might sound okay with a 4-10 bottom......

Any suggestions would be appreciated.

Thanks!
Diode Breath

[tonezoneonline]

The Princeton is a very nice amp.Why not sell it and buy a 18 W kit from Weber.They are a very good bang for the buck.

[tonezoneonline]

IC.I would check out 18watt.com or the Hoffman boards.I'm kind of partial to the Hoffman boards since I build them and they are turrets.I like turrets but there are a lot of good designs out there for this circuit.I love 6V6 tubes but don't think they will get you where you want to go with this circuit.

[Tom Phillips]

I'd like to second both comments from Tonezone.
I'd also add that an 18W Marshall built around 6V6s would have quite a different personality than the 18 Watt with EL84 circuit and OT.
I think you could fund your whole project for what SF Princetone Reverbs are going for.
Regards,
Tom

[misterdontmove]

4001

The marshall 4001 uses 6v6's....That might be a cool amp to build on that chassis ! They are getting expensive and near impossible to find... I wish I never got rid of mine !

misterdontmove

[Bruce / Mission Amps]

YEOW!!

I guess you could sell it and waste your money on buying an 18 watter kit, which just about everyone I know tires of fairly quickly.
IMHO, with not too many dollars and few parts swaps, a silverface Princeton chassis can be re-made into a 6V6 Voxy/plexi'ish amp that will blow any standard homebrew 18 watter so far in the weeds it will never be found...
PLUS when done, the hotrodded Princeton will be about 50% more useful to boot.
The 18 watters are fabulous looking and have a great overdriven screaming monkey tone and all that rot... but unless you are just dead set on having what I think is a one trick pony, and you don't go out playing with many other muscians, my opinion is to mod the basic Princeton into someting useable.

[R ski]

I couldn.t find a Princeton scheamatic. However, the power amp
cicuitry from the splitter input probably is simular to a Marshall.
Leave that circuitry intact.

The marshall preamp consisting of two tube, differs from Fender.
Copy the circuitry and you will be wailing in no time.

[Fred G.]

And now the question would be...

OK, I'll bite:

Bruce - what are the parts swaps you mentioned to Voxify/Plexify a Princeton?

Thanks in advance,

Fred G.

[Rick Erickson]

6V6's won't have enough gain to sound like an 18W Marshall. You could convert the output tube sockets to 9 pin miniature types and use EL84's. The OT will work fine. Your best bet for a rectifier would be the Sovtec 5Y3GT. It's the closest thing I've found to the EZ81 in an octal package. I think Weber VST sells converter plates for the Octal tube sockets.

RE

[tubelovin]

I agree and disagree with all those statements. The 18 watt isn't a one trick pony if set up correctly, but unless you hate that princeton I would keep it, and possibly moddify it. I've made the mistake, as have most, that you sell something just to wish you had it back later. Also I wouldn't trade one for the other because you might end up with something you don't like, then you've got nothing. My advice talk to Bruce and build a 18 watt also.

[Guitarist]

Also, I had on of these and built the Promaniac into it. It took a while but she totally wails and is very versatile. Fender and Marshall in one amp and I've even carried it on the bus (untill my unreliable Volkwagon/Audi caught fire whence I switched to Subaru).
I remember the Princton had alot of useful pots with switches which is handy.

[drewl]

Wow, pretty harsh words for the 18w!

I haven't tired of the one I built out of junk parts, and with some tweaking I enabled it with some footswitchable tricks that make it an extremely useful amp that I can play with my band doing all sorts of covers.
The great marshall sound in a low powered amp...what more could you ask for?

I'd keep the princeton stock for alot of people value them, I sold mine long ago...didn't do it for me...

[TD_Madden]

Bruce,

I've got a SFPR hanger-queen......and I'm intrigued by your suggestion. Any link you can point me at?

[Dutch]

6V6's won't have enough gain to sound like an 18W Marshall. You could convert the output tube sockets to 9 pin miniature types and use EL84's. The OT will work fine. Your best bet for a rectifier would be the Sovtec 5Y3GT. It's the closest thing I've found to the EZ81 in an octal package. I think Weber VST sells converter plates for the Octal tube sockets.
RE

Another thing to try that, IMHO, works well is using 7591s in place of EL84s. They bias up virtually identically to EL84s, fit in an octal socket (handy if that's what you've got! ), and are running way under max plate dissipation and plate/screen voltage ratings when used in place of EL84s, so they'll last a long, long time. Slightly beefier tone in the lows, but plenty of jangle. I built an AC15/4 "lite" circuit (just the EF86 channel) around them, with no changes from the stock circuit except the 7591/EL84 swap. It kills!


HTH!

C ya,
Dutch

[Matt T.]

You could try the Blues Express circuit. It uses EL84s too but it might sound OK with 6V6s. One thing you might want to look into (if you haven't already) are two simple, popular Princeton mods: one is move the connection for the PI power supply node to the unused (higher voltage) node and another is to run the cathodyne splitter fixed-bias. There are names for these mods but I can't remember them (PaulC mod?).