New amp project... 18 watt marshall clone

[Twisteramps]

Well, looks like I'm building a new project - an 18 watt Marshall all tube head. If there's any interest I may show the steps with lots of pictures - it's going to be scratch built, no kits. I did a set of custom faceplates for it that are in the process of being created, and have my schematic/layout ready. Now to just order all the parts and build the damn thing... [img]/images/graemlins/wink.gif[/img]

[toejam]

Re: New amp project... 18 watt marshall clone

Sounds cool! I'd love to see all the steps and pics. [img]/images/graemlins/smile.gif[/img]

[Shawn Lutz]

Re: New amp project... 18 watt marshall clone

sounds cool Pete...sounds like work too [img]/images/graemlins/smile.gif[/img]

[Twisteramps]

Re: New amp project... 18 watt marshall clone

Well, I'm going to build a pretty much 'stock' one for a baseline, before I go crazy with mods. It should be fun. Hardest part will be drilling the chassis (total pain in the ass, IMHO, even with a drill press) and lead dress.

Pete

[rstites]

Re: New amp project... 18 watt marshall clone

Pete,

I'm interested in pics and details of what you're doing. Did you decide to go with the TMB version? I saw your posts on the 18W group and figured you'd build your own chassis vs. pay $250+ for someone else to do one! (Some of those guys sink a ton of $ into these builds.) Drilling and punching a chassis isn't too bad as long as you stay with circles. I put the computer style power chords on mine and they're a pain to get right. I tape a piece of engineering paper on the surface as a guide, so all the holes lines up. I know from past experience that I can't just eyeball it and get it right! I'm curious about your faceplates too. Is it just me or is the whole chassis cutting, box building, painting, and lettering about 90% of the work on these projects and the electronics the rest...

I'm curious because I'm building something in the same realm this fall. It won't be an 18 W copy, though it will be Marshallesque and run a couple of EL-84s.

Ross

[Twisteramps]

Re: New amp project... 18 watt marshall clone

Yeah, I'm building a two channel with a master volume and gain/bass/mid/treble tone stack and the other side will be a tone/volume only. I had to make some changes to the faceplate to fit a 16" across chassis, but the cost of buying a blank 16x8x2 and having custom faceplates made was much cheaper than just buying a chassis. Here's what my faceplate is going to look like:

http://mothrastewart.com/images/18wa...8_TMB_Pete.pdf

One thing I had to pull was the standby switch. However, I found a vendor that sells a switch that can go into standby in the middle position, then full on - so you get full functionality without two spaces. This first one is going to be tube rectified, so it doesn't need a standby. Or I could put the standby on the back. Also, I'm not using 4 inputs either... seems like a waste to me.

I usually print out a 'map' and tape it to my chassis before I drill so everything is straight and where I want it... it's just time consuming. I really enjoy wiring the amp, putting the components in and building the turret board from scratch the most.
My face and backplate are ordered, but I won't see them for a month. I did em in plastic that is reverse cut, and the same color as the marshall ones. I'll probably also put a small marshall logo on the head and use marshall knobs too.

I'm going to try some hammond transformers on this first one - see how well they do. I know the Matchless set I put in my Spitfire would work great too, but they are kinda pricey... mine were around $200 shipped for a set. ouch. The Heyboers are around $150 I think. I'm using some pretty solid Hammond iron... almost tempted to build one of these amps with Hammond transformers that are underrated, to get more of the vintage 'cheap part' mojo going.

Pete

[horns666]

Re: New amp project... 18 watt marshall clone

Pete if you make a 180 wt version...I'm interestested!

it's easy...just add a 0 to the 18 you already have.. [img]/images/graemlins/tongue.gif[/img] [img]/images/graemlins/toast.gif[/img]

you and my old friend Mike "Dr. Z" would have a field day! [img]/images/graemlins/tongue.gif[/img]

[Twisteramps]

Re: New amp project... 18 watt marshall clone

Bill - I have a schematic for a 435 watt 6x6550 power amp. Instead of a 12ax7 for the phase inverter, it uses a 5881. [img]/images/graemlins/laugh.gif[/img] Pretty scary, eh? I'm not sure how he's getting 435 watts (guess it's peak), but it's a Kevin O'Connor design.

Pete

[horns666]

Re: New amp project... 18 watt marshall clone

SHEET...Pete..

why don't you build the BILL Z BUB model...

that's sounds like THE one dude!!!!

I'm all about headroom and preamp distortion...you could gimme dat!

BTW...can you put a built in glory hole in it...just askin.. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/toast.gif[/img]

[rstites]

Re: New amp project... 18 watt marshall clone

I don't have any data sheets in front of me, but I don't think 435 W from 6 6550s is unreasonable. I think you can run a pair of 6550s at around 75-80 W. We're just used to seeing them in Marshall amps designed for 50 or 100 W.

Yeah, glory hole, no problem. Just use the 1/4" jack in the back hooked to b+ and ground. [img]/images/graemlins/wink.gif[/img]

[Twisteramps]

Re: New amp project... 18 watt marshall clone

Ross, there is NOTHING reasonable about 435 watts! [img]/images/graemlins/smile.gif[/img]

Pete

[rstites]

Re: New amp project... 18 watt marshall clone

For bass or a PA maybe...or not. [img]/images/graemlins/smile.gif[/img]

FYI,I just finished (?) a P1X last night before leaving town. It was my first true scratch build and I was pleasantly suprised that it worked fine after only one initial problem (forgot to tie pins 4&5 on the 12ax7 for the heaters). It definitely needs some tweaking when I get back. It goes into oscillation with the gain past 3:00. It's a bit farty with chords, but I was using high(er) gain pickups. It sounded pretty good for a raunchy blues lead, and may do well overall for single coils.

That's why I'm doing it first though. My tech skills aren't up with my engineering skills. I learned lessons I really should have known: don't build directly from the schematic (rats nest!) and related to that, I really need to go to a tag board rather than terminal strips. It'll force me to clean up things some. Speaking of which, do you have a good source for get tag board and hardware?

[Twisteramps]

Re: New amp project... 18 watt marshall clone

I've been getting sheets of G10 Garolite for my turret boards and cutting them to size myself. you can get them at mcmaster carr (do a google for em). hardware it just depends on what you're looking for. hoffmanamps.com has a lot of stuff, and he has great service. I get as many hardware pieces as I can (screws, lock nuts, bolts, etc) from the local home depot. Some of these places really try to rip you off on stuff that you can source pretty easily.

On your oscillation, a really quick way to cut it is to use shielded cable from the input jack to the first stage. Only ground one end of the shield - typically the 'input' side if you can. If that doesn't help, then shield the other grids on the preamp stages too. It may also be grounding - I've had good luck running all of my poweramp grounds seperately from the preamp grounds. Also try to make it flow from input to preamp to poweramp as 'one direction' as possible - try not to double back with any signal if you can help it.

Also, regarding the tag boards email me if you want and I'll put one together for you for cost of materials. Whatever you do, don't use eyelet boards... those suck.

Pete

[Stinkbug]

Re: New amp project... 18 watt marshall clone

I am interested! I have always wanted to build an amp. So it would be cool to see the steps with photos and junk. Maybe sometime you could do a JCF amp and those interested can attempt to build along with you...you could be the Bob Ross of JCF!!! [img]/images/graemlins/smile.gif[/img]

[Twisteramps]

Re: New amp project... 18 watt marshall clone

I'm too mellow to be Bob Ross [img]/images/graemlins/wink.gif[/img]

Pete