One small step at a time OR my 18 watt Marshall build

ezietsman

So I've decided to build an amp. A twin channel 18 watt amp based loosely on the 1974x Marshall from the 60s. The first channel will be more or less the same as the original 18 watt's, just a volume and tone knob and very little gain from the preamp, all the drive will come from the two EL84s in the power section. The second channel will have Gain, Treble, Mid, Bass and Master Volume. This will be a higher gain channel with more preamp drive than the normal channel. Befiore you ask, the gain knob and pot will go into the lo input on the second channel, as I won't be needing that input ?

Instead of having a power switch like all other amps (design flaw), mine will have a switched pot that switches it on and off (duh!) as well as control the loudness of the amp by varying voltages to the power amp and phase inverter. So I'll be able to get proper power section drive at any volume.

To get things rolling, I present the first component of my amp, its also the only one I have at the moment.

THE PLEXIGLASS FACEPLATE!

more to follow...

Gearhead

Yeeehaa! Another guitarist on the forum that decides he needs to build something because what he wants is not available in the shop. Best reason ever. Cool!

Jack-Flash-Jr

Very cool... but spotted a missed opportunity to make your amp go up to 11!

arjunmenon

Gearhead wrote: Yeeehaa! Another guitarist on the forum that decides he needs to build something because what he wants is not available in the shop. Best reason ever. Cool!

+1 GH

Jack Flash Jr wrote: Very cool... but spotted a missed opportunity to make your amp go up to 11!

? Or get vintage 40s made by a guy in India

Totally cool, ezietsman!
A friend and i are working at a similar 30w build (he's doing the gadgety bits , while i'm building the cabinet).

RobbieZ

Brilliant. I am planning my own system from guitar to amp. I have send you a personal message. There you can tell me to go away ?
Robbie

ezietsman

RobbieZ wrote: Brilliant. I am planning my own system from guitar to amp. I have send you a personal message. There you can tell me to go away ?
Robbie

I'm not like that. As far as I can see, there is no copyright on this amp. The schematic is freely available. See the image. I'm not going to use a circuitboard but I'm sure if you have an electronics background you can create one. I'm going to build it on turretboard (like in the old days) so I can easily modify it later. I'm ordering a kit that will provide things like the chassis, head cab, valves, retainers, sockets etc. and I'm using this schematic to build the amp (the kit is for a single channel amp).

RobbieZ

Thank you very much. Is it possible to send me a scan of the front plate, that is on your photo? This is not too difficult to build. I think the cost will go into the valves them selvs.
Robbie

ezietsman

I'll post it later, I know where I can find one but have to do it at home.

ezietsman

RobbieZ wrote: I think the cost will go into the valves them selvs.

Keep in mind that the output transformer may also cost quite a bit depending on what you get. Then there is the issue of a speaker, if you have a cab then you're fine but if you don't then you need to build/buy a combo cab and speaker or a cabinet. These options are more expensive, especially if you want good speakers.

ezietsman

Amp parts paid for. Should be here sometime next week 8

Edit: Parts are probably shipping next week I'm told.

Edit: Parts arrived today! Need to go and figure out where they are, want them before tomorrow afternoon. UPS got them here in less than 2 days.

ezietsman

Well at last I got my parts, here's the necessary picture for you people to drool over. Pretty much a heap of components now (clearly), I'll be posting regularly as I get along. A few cliff jacks and a new front plate for the head box are on the way, the guy at Valvepower said he'll send those when he gets them, thought I'd like the rest so long. Nice guy.

I'm currently working on the layout as there isn't one for this particular design available. I've decided to make a step-by-step illustrated guide of my build and I'll post the source code and pdf somewhere where anyone can take it and use it for whatever they'd like. (building their own amp, for instance)

OK more later!

Reinhard

Very cool! Can't wait to hear it ?

singemonkey

Freakin' exciting. Can't wait to see the progress.

TomCat

Nice one......its alway exciting to build something yourself....the key is to exercise patience and not try to rush it.

ezietsman

Layout, work (very much) in progress. Hopefully I can upload the file and it will keep updating itself.

guidothepimmp

EZ?

What sort of voicing is this ampmeant to have?

ezietsman

guidothepimmp wrote: EZ?

What sort of voicing is this ampmeant to have?

The lite iib channel is more or less a straight copy of the Marshall 1974x's Normal Channel. Crunchy old school overdrive when cranked, all coming from the EL84s, no preamp drive, think early ZZ Top. The superlite channel is more like a 70s plexi due to its increased preamp gain levels, think early AC/DC / Maiden. That sort of thing. No modern tight metal chugga's to be had here (not without some simple mods).

guidothepimmp

nice.. look forward to hearing this..

ezietsman

An almost completed layout. Gurus' advice, comments will be appreciated ?

and a link to the fullsize version
http://crashtestastronomer.files.wordpress.com/2011/04/ewald_18watt_layout2.png

and a link to the schematic
http://rh-tech.org/public/18-Watt/18_Watt_LiteIIb_Superlite_VVR_PA_PI_162.gif

Gearhead

Not being a guru, I can only note that I would connect the v1 grids to the inputs ?
But seriously: the input circuit has some variants depending on what you want to achieve. Mesa has even done the 'tie guitar to grid and nothing else' thing...