cfishbowl

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That is a bad idea unless you want a serious rolloff above 10kHz. You can't find the optimum value of this cap without an oscilloscope. If you have to add this cap use a small value e.g. 330pF I also wouldn't do this, the resistor is there for a reason which is to stop oscillations. JPM- Got it. Perhaps once I get it done, I can con my buddy (an electrical engineer) to bring his oscilloscope down for some testing once the original design is done.

Hi all- Thanks again JPM and Matt for spitballing this circuit design. I did some checking and it will be about $100 for the extra materials to build the revision as suggested in post#32. Most of this cost will be for a decent pair of 6267 tubes and some decent 0.22uf coupling caps. The rest for new electrolytics and resistors. While this is not a huge issue, I do already have everything on hand for the original circuit. So in the spirit of educating myself, I decided to start with the original circuit and make the following adjustments. As suggested earlier, I will byass the feedback resistor with a 0.01uf 450vdc film cap. Also, as matt suggested, I will replace the resistor on the ultralinear tap with a 21v/3watt Zener "bypassed" with a 0.01uf/350v film cap. Please don't take this as my not trusting ya'lls advice. I don't believe for a second that Matt and JPM's circuit revisions would be anything other than amazing. But I thought I would start original and once I've listened to that for a while, I can order the new parts, make the changes, and then take another listen. After all, that's part of the fun of this hobby. I hope you guys aren't offended or you feel as if I wasted anyones time. I am very very appreciative. I'll report back. Thanks! -Corey

JP and Matt- Thank you guys so much. I've got lots to think about. I'll report back once I have decided and built the amp. Appreciate your input and design help! -Corey

Matt- Also, one more grounding question for you. Since the chassis is now anodized inside and out (NO longer electrically conductive), does this change your grounding advice at all? Just curious. Thanks! -Corey

Didn't see the other replies regarding the audio circuit until I had already posted last thing above. You guys are way more advanced than me, very impressive. I guess I just need to build it one way or the other and see. Matt, sounds like you are pretty confident that things will sound good with your revision, so if it doesn't end up being a bunch more to order the new/different parts, maybe I'll just build it that way and see... I do appreciate both of your input though, shows how much I have to learn. Corey

All, thanks so much for the help. So: My plan, I think is to keep the PS as is with Matt's suggested changes in terms of grounding. I'm going to build up and see what B+ is after building the PS section. I will order a 100uf cap for C8 and some alternate values for R14 to help put B+ around 305 or so. A note about 6v6 plate and screen voltages: So the north American distributor for JJ electronics (eurotubes.com) is about 15 min from my house so its super easy to swing by and talk to those guys and pick up tubes. This means I end up using a lot of their stuff. I bought the JJ 6v6 S to use in this amp, which is a beefed up 6v6 and per the JJ spec sheet, if I am reading it right, can handle plate and screen voltages of 450V, so I'm not too worried about tube life. JPM, I am planning on using the specified Edcor OPT and PT. I have the iron already so am pretty committed to making it work. I don't have an oscilloscope nor the expertise to use one so I'll have to do the best I can with what I have. Appreciate you guys chewing on this for me, and Matt, thanks for the schematic work. -Corey

Also, Maynard, I am curious... Would you mind learning me? Sent from my iPhone using Tapatalk

Hey thanks a bunch guys. I'll skip the triode switch then. Matt, I really really appreciate your help. I noticed you eliminated the volume pot from the circuit. Not a huge deal since I have a buffer as my volume control but I thought it might be nice to leave in for channel matching? I'd love to hear your take. If I do, I assume I can just shove it in there? I'll look at the two schematics and figure out what I have already and what I would need to buy to make the proposed changes. I have no doubt it'd be worth it. Maynard, Joe, and wdecho, thanks for your input as well. I'll keep ya'll updated. Sent from my iPhone using Tapatalk

Hey Matt, not very. Basically wired the fuse, iec, and on off switch. Haven't wired any of the actual circuit yet. Probably won't get to do too much more for a few days. Sent from my iPhone using Tapatalk

Hey all. I'm somewhat new here. Ive built a few kit projects, most recently a decware zen kit which I really like. Anyway, I just finished Ed Jurich's book and I am in the middle of building the 6v6 single ended amp found here http://www.ejjamps.com/articles/6V6SE-6L6GC-amplifier-circuits.html The only mod I am doing is putting in a heater switch so I can run 6cg7 in addition to 12au7/12bh7 My question is whether it is worth putting in a triode mode switch so I can run the 6v6 in triode mode. If you guys think it would be worth it (I don't need more than 1-2wpc with my speaks), would someone be willing to draw it for me quick? I'm a rookie. Thanks folks! Corey Sent from my iPhone using Tapatalk

Sweet. Thanks Matt! I live in Portland, or so it better be a free range, organically and ethically sourced humanely prepared burger and fries with artisanal ketchup. [emoji23] Sent from my iPhone using Tapatalk

Matt, you mentioned Edcor earlier. For those of us partial to their transformers, would something like the xpwr001 be a good choice? Seems like this would be a way to run the hv, the rectifier filament, and the filament for the preamp tubes all with one transformer. And it's 46 bucks. Thoughts? Sent from my iPhone using Tapatalk