YMI's 12xxxx build - feedback please

[YMI5150?]

Bens 790 is on V2a as of last night. I added it with the fat cap. BTW, I think you're right in general but Ben was also right that 330 was way excessive. the 33uf I put on last night shows some promise. But like I said, two paths show similar results. .68uf mustard with resonance pot on the guitar rolled off a bit to tame highs, or 33uf electrolytic with resonance pot maxed. I have a pass to dial this in after work for a few hours. I'll have this flushed out before tomorrow's second tone summit with Mike and Eric.

What do you think about the 16 ohm tap? I recall Rockstah liking it. Will have to dig a bit to see what Ralle likes.

[YMI5150?]

ok, need your ears to try to wrap this up if at all possible.

Once I get past my mistakes , a few clicks flat tuning and right channel not dialed yet, my ears tell me the amp is close. it sounds like it could be tightened up a bit and maybe just a tad hotter. I've got some more Isrkas coming and CM PT.

Board looks about like this but with a couple more isrkas, a 33uf fat cap on v2a, nicer bias caps, and a 100uf PI can (not shown).

board_1 2.19.12 small.jpg (136.99 KiB) Viewed 1993 times

thinking of trying a slightly higher NFB circuit. currently 100k/4 ohm. Might try 100k/8 ohm.
my fat bottles are not well matched and I biased to the one hot tube using the 1 ohm resistor method. I may grab a matched set of EHX fat bottles and bias the old fashioned way.

Input please.

target iso track
http://www.youtube.com/watch?v=r3E_m7IhSfY" onclick="window.open(this.href);return false;

current status using model a (dsd w RC circuit), slaved to pulsonic
http://www.soundclick.com/player/single ... 02284&q=hi" onclick="window.open(this.href);return false;

[Strat78]

It's just not cooking enough. The low E is a little cottony with the fat cap. The pickup is not pushing enough. I worked with the mxr 6-band last week and came to the conclusion that a more transparent EQ would be better, like the GE-10 for a simple treble boost. The variac is puzzling me these days, not sure it is being used right for what we want. Maybe Ed only had it between the cab and the head like we discussed a couple of years ago or just used it live. The PT needs juice to sag nicely, but the variac only takes it away! Straining the tubes is nice but at the cost of truly fat clear tone. I just don't know anymore.

[YMI5150?]

love the adjectives! Keep em coming

I switched the selector switch back to 16 ohms after getting a text from Eric saying how elated he was after doing so on his 800 mod5 with fat bottles. I noticed a nice shift down in frequencies. the low end tightened up, hit harder and was less "cottony" or I'd call tinny. the high end was less harsh. there's a sizzle on the first record but its more pronounced on the Franky than the Destroyer so I think I'm going to put the burden on the franky guitar to get that extra heat for those tunes. The Destroyer tunes appear to be very close. I still may try to tighten up the distortion with higher NFB next time I crack it open. I'm going to be pretty busy building this other 12 series so this might be it for a while on this one. I'll get a clip posted to document its current status.

Regarding the fat cap, my understanding is it does not add bass. it attenuates highs to ground, giving the perception of a fatter tone. this i do feel is important at giving that killer fat midrange. the trick is finding the right value to drop the slope of the highs off correctly.

[Strat78]

It's good to get another build going and step away from older projects to allow the ears to un-calibrate to things that have become too familiar. Still, I know Ralle likes the 16ohm setting as well and has fought long and hard to covert people, but I still like 8 into 16ohm cabs. Put some matched tubes in there even if they are el34's just to hear if that makes a diferenc. Robert likes to put the weaker tubes at socket 5 and 6, which works pretty nicely.