new Rocket Reverb project

[telentubes]

Although I’ve been visiting this site daily for many months, this will be my first post. I’ll offer a brief introduction before asking my first (of probably many) question about my upcoming Rocket Reverb build . Skip this intro and go straight to the question if your not up for a paragraph of drivel!!! I’m 55, happily married, and about 20 years into building fretted stringed instruments, primarily mandolins, for a living (my way outdated web site is www.fletcherbrock.com). I’ve supplement with gigs for 30 plus years in acoustic and electric settings. Until about 2 or 3 years ago I had always played with “store bought” amps, Fenders, Voxes and Mesas. I had always paid close attention to the tone of acoustic instruments, but for some crazy reason, amps never figured in to my world view. Then, one eve in Seattle, I went to a Bill Frisell concert and was knocked out by his tone. If I like what I hear, I typically check out the gear on stage. A week later I played a gig with Orville Johnson, also amazing tone. Both were playing through Jack Anderson amps. The light finally went on. I ordered a 20 watt Anderson, waited the 18 months to get it, then ordered a 45 watt the day I picked up the 20. I was so taken with the complexity of these hand build amps that I became mildly obsessed with their workings and decided to learn some basics of tube amp tone. Really not so different than dealing with the zillions of variables that add up to make a mandolin. I’ve had the Andersons for about two years and they have changed my playing considerably. I’ve built 4 amps in the past year, 3 Fender styles and 1 Vox. Along the way I discovered Ken Fisher, Trainwrecks, this site, and the Rocket. In particular, the reverb version seems to fulfill a lot of what I'm looking for in an amp . I’ve got almost all the parts gathered, with apologies to folks like RJ and others who sell some of this stuff. I didn’t realize they were available from folks on this site till after the fact. Next time though!

My newbie questions concern the often flogged tranny placement dilemma. On my last build (the single channel Vox AC15 from Tino’s book), I used a different chassis shape and size than recommended, which changed the layout. So using the headphone trick to place the trannys (my first time and I love it), I ended up with a dead quiet amp. When using this method to lay out the Rocket, I find that the OT hum is quite loud when using the traditional KF placement (I’ve got the Heyboer tranny set). It’s not bad if I flip the PT on it’s side so that the laminations are horizontal (this will of course require cutting a hole in the chassis to recess the end bell), and it’s not bad if I place the OT over the circuit board like the M Fowler versions (and others) of the Normster RR I’ve seen posted. I would prefer to use either the Fowleresque layout, or the one with the laminations of the PT on it’s side.

Do folks have a preference?
Is it O.K. to flip the PT on to it's side?
Will having the OT over the circuit board (Fowler version) introduce hum or hiss?
Should the rectifier be moved over to the area facing the end bell of the PT (again Fowler pics)?

I’ve noticed that putting the choke between the OT and PT will kill some of the hum. It is however, not the quietest place for the choke. Is a noisy choke (in the headphones) a problem?

Is it OK to spread out the tubes a little bit (heat?)

OR... Should I just go with the more trad looking layout and simply cut the hole and turn the PT on it’s side and get started? I’m leaning that way a little so it will keep most of the rest of the amp the same as the KF version.

I’ve posted a couple of pics with the two options I’m thinking about. I hope all this makes sense.
Thanks to everyone on this forum. I have seen some stunning work and brilliant problem solving and innovation, most all of which is way over my head. I’m having a ball learning about amps.
Fletcher

[M Fowler]

Fletcher

That's a hard question to answer. If you have not built a traditional TW Rocket I would suggest going the Ken F. layout no matter what your headphone is saying. Notice that the choke sits out front on the layout. I would not cut out the chassis and lay the PT down.

I prefer the Dr Z layout with all tubes across the back for ease of changing out the tubes is why I did that, like a Fender too. rj and rawnster have built Rocket Reverbs in TW style I believe.

The main problem is reverb tank magnetic coupling causing slight residual hum on some amps. One has slight hum, the 100w has more and the Fender style I just completed 60w is dead quiet go figure.

Mark

[sliberty]

I would not cut out the chassis and lay the PT down.

I am currently getting started on a Rocket 4x10" combo, and due to the layout of the speaker cab, I decided to use a laydown version of the PT (same model, just different mounting hardware).

So I am especially curious about why you say don't lay it down. please elaborate.

[telentubes]

Thanks Mark. Always good to start with the tried and true, then jump off from there when you have a better idea of what's going on.
F

[telentubes]

Forgot to mention that my project is going to be a combo as well. A 1X12.
F

[M Fowler]

Sliberty,

You can use a laydown PT, I was referring to the OP question about laying his down.

I build an Express combo 212 with laydown PT.

I really don't like giving advice about amp layouts because a person needs to do what they want to do with their build and there is no wrong or right way as far as laydown PT or standup PT only that we need to be aware of orientation between the PT, choke and OT to reduce interaction and noise.

Sounds like some great projects you guys have going.

Mark

[M Fowler]

telentubes,

Yeah you failed to mention it was a combo alright

Oh well you can go with either laydown or standup in a combo, maybe will want to add a brace to help support the chassis on the PT side when mounting.

Your chassis is not the typical combo style chassis. I used a 18w Marshall channel type chassis from Dana Hall when I built my Express combo.

Mark

[telentubes]

Sorry about that combo omission. The chassis is from Watts Tube Audio. .090 aluminum. 2 1/2" X 8" X 17 1/2". On sale this summer for $36. Great deal if you don't mind drilling holes... which I don't.
Actually I'll interpret your advice as "do what you need to do within reason" which I think is good advice. I'd gotten a little gun shy when reading about the Wrecks, where folks sometimes stressed the importance of every single wire and nut being in an exact predetermined place, with any deviation resulting in a "howling mess". COOL... now I can start building.
tnt

[M Fowler]

Not to say you don't have to follow good building rules on any amp but the Rocket is the most friendly of the TWs. The Express is the finicky one.

You pointed out that you have building skills so I am quite sure you will build a high quality amp.

It took me and others quite a few emails before Ken Watt's decided to start making those mounting tabs in chassis for us. I use both kinds tab out or tab in depending on Marshall or TW style or custom jobber. I hope Ken is selling a whole bunch of them.