Deluxe Reverb, one channel, no tremolo

[telentubes]

Just the heaters left before checking the work several times.

JPEG image-2120E51677EB-1.jpeg

[Colossal]

Very nice, as always!

[martin manning]

Very nice indeed! looking forward to the smoke and noise tests.

[telentubes]

Sadly, it didn't fire right up. It produces sound, but it is greatly distorted. I'm not getting any voltage measurement for bias, so will dig into that as I imagine that's where the problem lies.

[telentubes]

The leads from the bias caps to the bias pot were reversed. Up and running now.

[telentubes]

The Allen PT has the juice for 6L6s so I stuck those in in place of the 6V6s. The voltages were a little high for my taste, so along with that I replaced the GZ34 with a 5U4GB rectifier tube to see what that would do before I messed with the dropping string resistors. Seemed to do the trick. Really great clear meaty tone without any ice picky highs so I don't anticipate the need for any tweaking. I used stock values everywhere.
However, it is not dead quiet. There is some hiss, and a little 60 cycle hum which may be because I stuck in funky start up tubes, or it's plugged in right under a couple of florescent lights, or because I didn't pay enough attention to grounding improvements that some have been using. All in all, very happy with first impression.
Bias 34ma
B+ 406, 403, 331, 291
V1 plates, 191, 190
V3 Plates, 194, 193
V4 PI, 180, 181
V5, 6 Plates, 400

[sluckey]

The bias seems cold for 6L6s. Or hot for 6V6s.

[pdf64]

The bias seems cold for 6L6s...

Maybe they’re 19W 6L6? If not, perhaps pretend they are anyway, then the idle dissipation lands close on 70%. After all, all 6L6 types have the same curves and characteristics, that’s what makes them 6L6

[telentubes]

Quick update...
Put it in a cab and compared it to the Princeton and JM Signature for base line noise, and it's pretty much the same. Definitely quieter than the '73 Silver Panel DR that I have, by a bunch, so I won't worry about noise floor.

Keeping the JJ 6L6GCs for the time being and went back to the 5AR4 rectifier, using a PSVANE that I just got.
Here are the new numbers.
B+, 423, 420, 344, 303
V1 plates, 199, 203
V2, pin 1 and 6 bridged, 402
V3 plates, 202, 201
V4, 186, 189
V5 and 6 plates, 414
Bias -36

Just going to play through this amp for a while and leave everything as is.

[telentubes]

Update.
So far I wouldn't call this amp a success. I like the tone a lot, but it turns out the noise floor is too high. Something ain't right. When the volume or reverb pots are turned up, it's bad.
I've pulled the board and made all the runs as short and direct as possible from transformers etc. Done lots of chop sticking, and changed the filtering in the power section. I reconfigured the grounding layout all without improvement. It seems there is some kind of ground loop, with intermittent oscillation and faint motorboating that comes and goes when the amp is just idling. It's stuffed into a small chassis so that may be a problem, with too much cross talk. I don't have a ton of time to put into this right now, especially after the rebuild, so it will be shelved for a bit. Anyone trouble shooting tips would be welcome.

[martin manning]

You might study the revised grounding scheme in the DR replica I recently did. You've eliminated the trem, but the other changes would be relevant.
https://ampgarage.com/forum/viewtopic.p ... 61#p428861

[telentubes]

Martin... I made most all of the changes that you suggested from your beautiful DR build, with the exception of the reverb section, which I'm still working on. It's going to take some rerouting and time but could be the culprit. I'll plug away at it and report back. Thanks.

[telentubes]

Grounding updated. No change. Will dig deeper as I must have missed something somewhere. I have a few ideas.

[martin manning]

Frustrating I'm sure, but at least you know one more thing that it isn't.

[telentubes]

Actually, really glad for the impetus to upgrade the grounding as it will be an improvement once I find the problem. Just being lazy. I should also change the standby switch configuration while the hood is up, or just get rid of it.