Amp's done (Rocket) - Smoke test tomorrow

[George61]

I received my new output transformer, a Triode A470-S. I installed it and my voltages seem to be in the vincinity now. All EL84 plate voltages are within 1 volt. The screen voltages are only ~1.5V lower than the plate but I'm guessing that's normal with 100R screen resistors.

Right out of the blocks this amp sounds way better than my 36W Ceriatone. No, none, nada, fizz.

With the amp out of the cabinet, I do have a squeal with the volume past 3 o'clock. Could that be cause by the output transformer primary leads being reversed? The Triode transformer has different color leads than the layout so I just took a guess.

Solder on,
George

[rp]

I need to decide on a Rocket OT and it's driving a bit batty. I had a real A470 set aside but it seems to have a bad wind so I'm pretty set on Triode's A470S. When you get the amp up and running well please report back on your thoughts.

w/o NF it shouldn't matter which leads go were but it doesn't hurt to flip anyway, I've had it work but maybe it was just the moving around that did it. Off hand I think Dynaco pairs were g/gw and b/bw (not sure which were the UL) and not g/b and gw/bw. I could be wrong and I guess you know all this, but if not double check.

Lack of cover will bring in hum and buzz not squeal, something else is up. Your layout looks ok, before you go nuts over it try rolling in a new pre tube, and if lacking then at least shuffle the three you have. Tap on v1 & v2 if ones real microphonic move it to v3. If you're using old pulls this should be your first trouble shoot.

My only critique is you should use black wire for ground only, I'll change other colors if I run out, but B+ I always make red and ground blk. Somebody else might have to work on it someday and working on an amp with black for signal would be aggravating, to me anyway.

[George61]

Swapping the OT primary leads cured the squeal, but that may be because I have the leads positioned slightly differently.

Don't know what to say about the Triode A470-S because the Heyboer I bought was bad out of box so I have nothing to compare it to. What I can say for sure is this amp is amazing, even with no time on it. It has a fat, smooth sound that would give 65Amps amps a run for their money. I can not over emphasize how smooth the overdrive sound is. No fizz, no harshness. That's with new production tubes: Tung-Sol 12AX7, JJ EL84, and Sovtek GZ34. The guitar that I am using is a Jackson Dinky with medium output, alnico magnet, humbucking Dimarzio pickups. The guitar also has a bell metal block on the Floyd Rose tremolo, which makes a lot more difference than one might think. Since speakers make a huge difference in sound, I guess I should state that I am using a 2-12" sealed cabinet loaded with a 100W Scumback M75 and a 100W Scumback H75.

This is only my second vacuum tube build but I have built several solid state amps and I usually do pay attention to the wiring color code. The problem is, that is that I usually use teflon wire, which I have a lot of, but I wanted to use the 'official' 300V, 20 AWG, solid core wire for this amp. I have a 100 foot spool of black but a very limited selection of other colors so almost everything ended up black.

[Reeltarded]

It's a stunning build. I hope swapping the tranny didn't cause to much mayhem in there for you.

[George61]

I added a picture of the amp in the cabinet to the first post.

Solder on,
George

[M Fowler]

Very nice cabinet she looks great.

Mark

[Colossal]

Great job on the amp and fantastic looking cabinet! Nice way to close out the project. Now crank the Volume and enjoy!