Minor issues with a new build

[tubeswell]

A smaller V1 coupling cap? What kind of effect will that have on the tone? Brighter? Darker?

Generally less flab on the bottom end and brighter, depending on how small you go. You canalways put bass back in at V1b with bigger bypass cap and bigger coupling cap

My big issue is to make the annoying feedback go away... any idea what might accomplish that?

You mean you are getting feedback when you have the geetar doing power chords and the amp dimed? (There is no NFB loop in your schematic. If you add one, it will tame the amp a bit. Look at the 5F1/5F2A style NFB loop and go from there.)

[Chuck H]

I hate to say it but your layout and lead dress are awful (not the work-the geography). A very thoughtful change to much of the lead dress MAY stabilize it but I wouldn't hold my breath. I hate to say this and your first inclination may be to deny it or maybe even get angry but I just want you happy with your build.

With your output pushing more into the preamp, your preamp pushing more into your output, the inverse orientation of the OT (compared to the 5F1 layout) and your OT secondaries routed back across the V1 leads you have a whole bunch of cross talk. Reducing gain via a tone stack or otherwise probably won't stabilize the amp. I think you need to re rout most of the leads.

[Howlin' Mad Mac]

Well as this is a prototype of sorts I'll be the 1st to admit I wasn't going for neatness here although I did my best to keep all the leads as short as possible with the exception of triming the transformer leads. I don't understand why the overall geography is faulty... I've kept the PT & rectifier to the one side seperating it from the main circuit, the filter caps are right next to the 6V6, the circuitry is located close to the tube sockets & the OT is located well to the opposite side of the PT & oriented at a right angle. I do see what you're saying about how I should unmount & flip the OT 180 degrees. Then the OT secondary leads would have a short, straight path to the speaker output jack however the primary leads would run under the cap coupling 12AX7b to the 6V6. Would I be better off if I ran the primary leads to a small terminal between the circuit & the pot? This would mean running longer leads around the circuit to the 6V6 socket & they would pass somewhat near the filter caps. As for taming this little beast down I scrapped the idea of a tone stack & added just 3 resistors instead (see enclosed revised schematic) & this got me to 90 - 95% of where I want to be. To get me all the way home I'm considering increasing the input resistor from 33K to 68K (lo input vs. hi input) &/or adding a 100R/10W between the rectifier tap & the reservoir (to reintorduce a little sag.) Any thoughts on these ideas? Also, can you or anybody recomend a better 6V6 OT transformer than the Hammond "Champ" replacement model? Something with a 16 or 8 ohm secondary or preferably both? While I do ultimately desire acceptance from the forum community I asked for your comments & critisisms so while from time to time something or other might "sting" a little I'm not angry at all, nor can I deny needing some assistance in tweaking these designs. All I ask is that ya'll remember I'm a tech, not an engineer so please attemp to explain these errors, not just "fix" them so I can walk away with a better understanding & create better, more elaborate projects in the future. Also I do read all of these replies & try to incorporate many of the ideas presented but at the same time ultimately I want to produce analog devices akin to the simple vintage designs of yesteryear but with something a little unique & different from everything else so please try not to be upset with me if I use an idea from another source. Finally regarding this particular build & its "flaws" at rest this design is quieter than any tube amp I've owned or built in terms of hiss, hum, etc. so I don't wish to dispute any claims of a poor design or need for improvement but I feel this design can be fixed & has some merit.

6V6 SE.pdf

[Howlin' Mad Mac]

Chuck, I also meant to ask what you meant when you said "your output pushing more into the preamp, your preamp pushing more into your output"? Please explain how this design is doing that.

[Howlin' Mad Mac]

Actually I'm getting feedback signal or no... & the frequency varies with a twist of the volume control. Was getting that from about 1 o'clock to max however since I've added those resistors (see attatchment to post below) it no where near as bad & only get from 3-4 o'clock to max... thing is tone is damn fine. Chuck thinks it's a lead dress problem & plan to take his advice & flip the OT 180 degrees & re-route wires so they are not in proximity of preamp tube wiring & see what the result is as soon as I get home tonight... other ideas I have are listed in post below if you care to have a look. Still haven't implemented a nfb into this design... if I can solve without would be preferable to me but not married to it. What do you think?