Layout Ideas

[mrn1ngstr]

Hello all, Im new here. Im a bit of a tinkerer. I prefer building things to buying them. I make my own booze, I build my own guitars and Id like to build my own amps. This is a topic Ive been researching and studying for a few months now and Ive bought an cheap old dukane amp to convert. Its a good little PP, point to point amp out of the 50's. The thing is, its got a decent number of preamp tubes (5x12AX7, 2x12AU7; power section has 2x5881 and 5U4G recto) in it and I can't decide what layout I want to go with. I have a pretty good idea but Id like some feedback. I really hate wasting space but that is a ton of stages. Ive read that its ambitious for a learner but Im thinking it going to have a couple channels. That said, I will probably still remove one AX7 all together. Im putting the schematic up for people to take a look at. Its old and a little fuzzy but you can get an idea of the way its currently laid out.

[IMG758]http://i241.photobucket.com/albums/ff18 ... e10fc.jpeg[/img]

[Cantplay]

Leave all the gain stages, and add a gain knob for each one.

That will make it versatile. You can get preamp overdrive, or power tube distortion.

John

[ampgeek]

Welcome mrn!

I see lots and lots of different options that could be considered here.

Tell us a little about the amp tone, feel, etc...etc.. that you are hearing in your head for this project.

What guitar styles and types of music do you typically gravitate toward?

What types of guitars do you make and use? Single coil, humbucker, other type of pick-ups?

Maybe share some clips and/or names of songs that posses your dream tone?

This will provide us all with a little bit of focus regarding a plan that could satisfy your desires. Or...lead to an onslaught of good suggestions to the point that you wish that you hadn't asked!!

Cheers,
Dave O.

[ampfab]

5881s make me think bassman or jtm45

[Phil_S]

Search the forum. The good people here recently convinced me to build a 6G4 in the Dukane someone gave me. I've done a number of amps in donor chassis and this one is no exception. It's my thinking that you'll get a better amp by stripping it and building the circuit you want rather than trying to deal with what you got. There were so many parts in my Dukane that were going to need replacement anyway, I couldn't justify reworking into something that I would have only the faintest idea of what it would turn into. Besides, if you are going to do the work, it is so much more fun to start from a blank canvas.

[armillary]

The guitar amps I've built all started life as either tape recorders or PAs. In the early ones I only tweaked the circuitry enough to get the amp working (replace electrolytics) and make a guitar sound good. But I always wondered how much better I could have done. So for my recent projects, I pick a Fender schematic I can respect (a Tweed, of course) and see if I could make it work with the chassis I have. First thing I check is if the B+ voltage out of the rectifier tube is close to the Fender schematic/layout. In your case you'd want 400VDC, not 250VDC or something low like that. If the Fender schematic/layout values are a good fit, I follow it as closely as possible, using the chassis, sockets, PT, OT and tubes. I buy new pots, caps and resistors according to the schematic and layout. You have to use point to point wiring because there's probably not enough exposed space to do it the Fender way, but that's the fun part, you really learn to read a schematic that way and the layout gives helpful information if you study it. For your project I would pick the Fender 5F6-A (I think ampfab is right), assuming your PT has enough 5V capacity to support replacing your 5U4G with a GZ34. When I'm done, at least I'll know what I was shooting for. Hopefully others will point out where I'm wrong, as I'm a newbie here.

[mrn1ngstr]

Thanks for the input guys. My original idea was to nix the bottom left AX7 on the schem, change the AX that forms the last gain stage and cathode drives the tone stack to a 12DW7 with the AX side still being the last gain and AU side driving the tone. Ill keep the recovery stage AU the same and change the PI to a 12AT7. I want to add a passive mid control, master volume, bias pot accessible from inside the cage and a standby simply for the ease of muting the amp in between sets. The pilot light is getting moved inside the cage which frees room for another control of some type. The 3 octal sockets on schem left are for mic transformers and are going. That frees some room inside, Im still wiring ptp. What I really don't have figured out is what to do with the first 3 and a half tubes in the signal path. Maybe should have led with that, but its good to get some fresh input from people.

Ampgeek- I enjoy rock and metal but I already have amps for things like that. Im looking to make something that has a clean channel that has sparkle and chime to it. I want a dirty channel somewhere around Pearl Jams Evenflow. Definitely not insane amounts of gain. I use mostly humbuckers, but recently Ive been working on the finishing stages of a 3 pu Jaguar with a tele neck pu, mid mini hum and a seth lover in the bridge. The body is a fender I bought for this project. The wiring is different than a normal jag to say the least. Although not a scratch build, still a very interesting guitar. You can see some of the progress here- http://reranch.com/reranch/viewtopic.ph ... highlight=

Armillary- The amp didn't work when I got it. Pretty much every cap in it was bad. A few resistors were kaput. Ive stripped it completely. The chassis and cage are getting recoated white and light blue. As I said before, I would like to keep some of the original circuit on this one but there are definitely going to be some big changes made. I have already picked up individual replacements for the can filter caps and some of the others that definitely won't get changed. No coupling, by-pass etc. caps will be purchased till I know what I want for the rest of the preamp. Also the original selenium rectifier for the bias circuit was fried so I got a 1N4007 for that.


In case you haven't seen this one, here is what Im working with.
[IMG764]http://i241.photobucket.com/albums/ff18 ... 7c8e1e.jpg[/img]

[IMG764]http://i241.photobucket.com/albums/ff18 ... 927404.jpg[/img]

As it is now. Theres a lot of holes that I have to plug.
[IMG:764:1024]http://i241.photobucket.com/albums/ff18 ... 418ee9.jpg[/img]

[TUBEDUDE]

Nice score! I love the look of the rounded corners on the cage.
I normally have the issue of not enough tubes to get all the functions I want.
You can use up a noval on an effects loop, and another 2 if you add reverb and tremolo.

[mrn1ngstr]

Thanks. I thought it looked pretty cool too. Im going to go with a blue and white powder coat color scheme. The blue pilot light inside the cage will give it a pretty cool effect as well. I had thought about a loop or reverb... I just don't want to dream too much bigger for the first build. Ive already been trying to figure out where to put the lasers and beer dispenser.

[TUBEDUDE]

Ahh yes, sorry, i missed the first build statement. In fact, you might consider setting this project aside for a month, and building one a little less complex and well documented to bust your cherry. A Champ would be a good starter project, and you can sell it fairly easily if you don't find you have a use for it. Don't underestimate value of acquiring the skills needed to build amps, in a crawl, walk, run progression. you will save yourself a good deal of aggravation.
Are you getting the powder coating done locally?

[mrn1ngstr]

Im already pretty invested in building this. While Im a pretty fast learner, Im also sure it'll still be a headache but Ill get through it. Im definitely going to need to pick peoples brains and get guidance on plenty of stuff. The powder coating is going to be done locally. Ive done up a few color sketches and picked one I like. The color is going to match a guitar that I refinished last year.

[IMG:764:1023]http://i241.photobucket.com/albums/ff18 ... d83fe3.jpg[/img]

[ampfab]

Doesn't the guitar player for pearl jam play a tweed bassman?

[mrn1ngstr]

The pearl jam bit was more of a rough idea I suppose. I don't want an exact copy of his tone. But I do believe they both used bassmans and marshalls back then. Not sure what they're into now... A bassman or something close might not be a bad start for this.

[ampgeek]

Nice looking axe!!

Yep...I think that the Fender 5F6A (59' Tweed Bassman) or the Marshall JTM45 (very similar plans) are going to be right up your alley and work quite will with the chassis that you are starting with.

Maybe add a V1a/V1b parallel/series switch to go from clean to grind? Looks like you already have an extra hole in the control panel just for that (Vol1, Vol2, T, M, B, Presence, Xtra for switch).

Great first build for one with your skills and "can do" attitude!

Rock on,
Dave O.

[TUBEDUDE]

I see you live in my hood, where are you getting the powder coating? I would like to get some done myself.