JTM45 Build

Littlewyan · Post by **Littlewyan** » Mon May 04, 2015 8:43 am

I think I'll keep it all standard. I was thinking of going all the way and making this an era correct amp with all of the correct parts, but the cost just shot up immediately and got a bit silly. So I think I'll keep the circuit original but use mostly new parts. May use older capacitors for things like the mixer bypass, tonestack and bright cap though.

Littlewyan · Post by **Littlewyan** » Fri May 22, 2015 2:14 pm

I've got my chassis and faceplates long with a few other bits from Michael at Modulus. The faceplates look amazing, I will post pics up once I've started building. However before I start building I need to decide what direction I'm going to take this amp in.

Basically I don't think KT66s will give me the sound I'm looking for. I watched quite a few videos of 66-67 Marshalls that used EL34s and thought they sounded fantastic. All of the Marshalls with KT66s that I listened to seem to have less crunch, less mids and the distortion that was there was a bit harsher perhaps? Definitely not as smooth as the EL34 Marshalls.

I've looked at various different Marshall amps from that era and I believe there were a few with EL34s that had white rear plexi panels.

What do you guys think?

Littlewyan · Post by **Littlewyan** » Tue Jun 09, 2015 10:15 pm

I ended up buying a transformer set from Classic Tone. Bought the JTM45 PT, 50W EL34 OT and 3H Choke. They arrived today.

First issue, can't install the PT as I don't have any Imperial American sized nuts. I need #8-32 Hex Nuts. Grandad has a box full of nuts and bolts so I'm going to go through that tomorrow night, if I have no luck there I'll have to order some online and wait a few days for them to arrive.

Second issue - Chassis has marks all over it from when I drilled additional holes. Scuff marks etc. Unfortunately I don't have a proper work bench so had very little space to work ;(. Anyway Michael at Modulus Amps said I should be able to polish it up again as its aluminum. Going to look into some stuff for that tomorrow.

joeboo88 · Post by **joeboo88** » Tue Jun 09, 2015 11:11 pm

Find your nuts!
And get us some pictures

Hope you get all your stuff without to much of a headache.

Littlewyan · Post by **Littlewyan** » Thu Jun 11, 2015 7:07 pm

Polished chassis with a few bits installed.

joeboo88 · Post by **joeboo88** » Thu Jun 11, 2015 7:59 pm

looking good...keep going...nice shine on the chassis

statorvane · Post by **statorvane** » Thu Jun 11, 2015 10:37 pm

Yup. That's gonna be a keeper alright.

Littlewyan · Post by **Littlewyan** » Fri Jun 12, 2015 5:18 pm

I've bought a Red Marshall 6V indicator lamp for the amp and the lamp has a little nib on it which pushes against the faceplate. Is there supposed to be a cut out for the nib? I vaguely remember the indicator on my 1987xl sticking out slightly on one side so maybe its just there to push against the faceplate.

statorvane · Post by **statorvane** » Fri Jun 12, 2015 5:31 pm

I've bought them from AES and Tube Depot. I do not remember a nib. Probably just some flash left over from the manufacturing process.

[img

768]http://i165.photobucket.com/albums/u76/ ... 35e3a5.jpg[/img]

[img

768]http://i165.photobucket.com/albums/u76/ ... 4ktrjr.jpg[/img]

ToneMerc · Post by **ToneMerc** » Fri Jun 12, 2015 6:46 pm

Littlewyan wrote:I've bought a Red Marshall 6V indicator lamp for the amp and the lamp has a little nib on it which pushes against the faceplate. Is there supposed to be a cut out for the nib? I vaguely remember the indicator on my 1987xl sticking out slightly on one side so maybe its just there to push against the faceplate.

I have filed the "nib" down just enough so I can push it through. You can file it completely down and use a Bellville push nut like the lamp styles without the nib or even use an E clip of the appropriate size to pinch the indicator shaft.

http://www.valvestorm.com/6vIndicatorInstall

TM

Littlewyan · Post by **Littlewyan** » Fri Jun 12, 2015 7:17 pm

Thanks guys.

With regards to heater wires and high voltage secondary wires on a PT is it ok to cross them? Its just with how my PT is laid out the 6.3V heater secondaries have got to go across the high voltage secondaries to get to the first valve.

JazzGuitarGimp · Post by **JazzGuitarGimp** » Fri Jun 12, 2015 7:26 pm

Littlewyan wrote:Thanks guys.

With regards to heater wires and high voltage secondary wires on a PT is it ok to cross them? Its just with how my PT is laid out the 6.3V heater secondaries have got to go across the high voltage secondaries to get to the first valve.

My first guess would be "it's all AC, so it doesn't matter". But that's all it would be: a guess. I'd be very interested to know if there is the possibility of interference from someone in the know.

statorvane · Post by **statorvane** » Sat Jun 13, 2015 1:35 am

Mine is parallel to the 120 VAC in the black amplifier. Here's a photo: [img

768]http://i165.photobucket.com/albums/u76/ ... vzolvv.jpg[/img]

Pretty quiet amplifier. Frankly, it's the best one I've built.

Littlewyan · Post by **Littlewyan** » Sat Jun 13, 2015 8:29 am

Yeah but it doesnt matter with the primaries. I'm sure it won't matter and the wires will be so long that I could re route them later if need be.

rp · Post by rp » Sat Jun 13, 2015 10:12 am

statorvane, who did those very nice looking cabs for you? Yourself?

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