YMI's 12xxxx build - feedback please

[vanhalen5150]

I have a full set of Pihers coming. I'm wondering what an entire amp would sound like with them in?

Those caps you got from Ben are "Phat"! If they were dogs they'd be the obese Pug's of capacitors.

[YMI5150?]

After my speaker comparison clip throwing me (and others) for a loop I thought the greenback was way too loose so tonight I thought I'd try to tighten things up by changing the tap switch to 16 ohms. The results seem to be fantastic. Clip coming. Wondering how a 100 uF preamp filter would do as DF suggests. Gain is awesome and it's a blast to play.

[Strat78]

You mean the purple wire to the 16ohm tap or just the switch itself and a 100uf PI cap?

[YMI5150?]

I remembered in my sleep that I mislabeled the can I wanted to change wow, do i have problems! Yes, I meant the PI filter up top. Everything else Dave suggests is taking me in the right direction so why stop there. I know there is a diameter issue with these chassis. can anyone recommend a great 100 uf PI can that is compatible with our builds?

yes, the switch itself so things are not mismatched anymore. I may do a clip with a few chords do document the change.

[Strat78]

I remembered in my sleep that I mislabeled the can I wanted to change wow, do i have problems! Yes, I meant the PI filter up top. Everything else Dave suggests is taking me in the right direction so why stop there. I know there is a diameter issue with these chassis. can anyone recommend a great 100 uf PI can that is compatible with our builds?

yes, the switch itself so things are not mismatched anymore. I may do a clip with a few chords do document the change.

The diameter will be a little more with the 100uf PI, but you only have to drill two extra little holes for the larger ring clamp. I've got a 100uf that I'll put in with the other stuff.

[YMI5150?]

wanted to remind the thread of the preamp tubes in this build:

Raytheon Black Plate (1962)
RCA Gray Plate (1959)
Sylvania Gray Plate (late 60s)

i bought those another lifetime ago from Marty over at the vintage marshall forum. his suggestion was to try the Raytheon or RCA in V1 for more gain. that may be the reason for the gain I have. Not complaining...

something else to explore that doesnt cost much $ or time...

[ValveStorm]

I remembered in my sleep that I mislabeled the can I wanted to change wow, do i have problems! Yes, I meant the PI filter up top. Everything else Dave suggests is taking me in the right direction so why stop there. I know there is a diameter issue with these chassis. can anyone recommend a great 100 uf PI can that is compatible with our builds?

yes, the switch itself so things are not mismatched anymore. I may do a clip with a few chords do document the change.

The diameter will be a little more with the 100uf PI, but you only have to drill two extra little holes for the larger ring clamp. I've got a 100uf that I'll put in with the other stuff.

Strat78,
What are you using for the 100uf PI cap? The only single sections I see around are the 100uf Eries, but they are only rated at 350v... might pop if the amp was run without the variac. Best think I can come up with is a 50/50uf ARS???

[YMI5150?]

interesting read on the PI section of the amp.

http://www.guitaramplifierblueprinting. ... verter.pdf" onclick="window.open(this.href);return false;

[Strat78]

The 350v Eries are good for the PI, that's what I'll send.

[vh junkie]

The 350v Eries are good for the PI, that's what I'll send.

I might try one in my 12xxx because the B+ tops out at 460vdc, so the PI would be below 350vdc.
I thought about is with my 69, but the B+ goes as high as 500vdc, and the PI was above 350vdc.

[vanhalen5150]

How much voltage should be draining to ground at the PI? Isn't that where a large portion of the v's get drained to ground before the preamp?

[YMI5150?]

I think the best way to summarize the current state of affairs is my amp has the classic Marshall tone now. It's browned out and really gravitates toward riffs on the second record. The buzz saw heard on YRGM is elusive. It seems to me it's a component material change rather than a value. It's very close but I need that edge without adding gain. Right now it growls rather than buzzes. Make any sense? Maybe a small electrolytic paralleled, bumping PI filter, or changing NFB to 27/16ohm like ralle. Suggestions before I try all 3?

Edit: is that a driver issue? Running split prerolas/v30s. Hear prerolas are woodier and black backs have the sizzle

[stef]

What do you have on V2a? A fat cap doesn't work for VH1 (yrgmn..) IME, .68uf is the way to go with the dime'd bass knob. I use a 100uf (stock seventies 50 + 50) Daly cap for Pi filter and 100k/ 4ohm nfb. Strat78 had that Vh1 edge with a xicon polyp. .0022uf and a"stock" V2a cathode (820/.68), i think... I have a mustard there, both .68uf are also mustards - The only thing I'm thinking about changing is .0022, I'd like to hear a poly cap there.
I really like china 12ax7 tubes in V1 and V2 - lots of gain and bite with a quad of JJ EL34 biased hot. I have a new set of eh 6ca7, haven't tried them yet...

[YMI5150?]

stef, see first post on the thread for pics. its an ADI silver mica .0022 uf. I dont like the fat cap either but I've reread the debate plexi thread and saw Ben suggest a small electrolytic, say 16uf. the combo sounded good to him. will give it a shot. the chicklet added sizzle and I'm sure the phihers will to when they get here, as well as the goodies Strat is sending.

like i said, the voicing is right, the crunch, the punch, its all good. the low e is a bit loose but that will go when the PI filter goes up from 32.

changing the silver mica .0022 to a poly pro might help too but that would be a stretch for one component to do. the black backs should add some sizzle too.
planning on changing the mustard ccs next to the chicklet and just to the right of the erie preamp filter (forgot the names of those components) with these to match up with the shots of Ed's baby whenever they show up.
http://www.ebay.com/itm/150747549815?ss ... 1497.l2649" onclick="window.open(this.href);return false;

I'll try to get a clip here so you can hear what's going on. boy home sick so I've got the day off. problem is he's sleeping next to the rig...

oh, i'm curious how a PIO cap would do in v2a. might give it a try. thinking out of the box a bit.

[YMI5150?]

Bias is now roughly correct. running 95 VAC, bias is 50ma on the hotter tubes. I've got 1 cooler one so I've staggered in matched pairs. I swapped two mustards for mencos (see pic). I have vintage preamp tubes so after reading Ed liked sylvanias there, I moved my two vintage sylvania to v1 and v2, and put the rayathon black plate on v3.

IMG_1635.JPG (212 KiB) Viewed 2546 times

This clip was really rushed so again, my bad on the slop. my wife was in the next room with the flu but I had to get it out there for your review.
its severely attenuated with a Hot Plate, bright switch on. so its overcompressed and a bit on the brittle side but not bad. this is almost bedroom level. mic is 2" off the dust cover (cloth removed). maybe a tad too close. input requested on mic placement.
all knobs (including bass) on 10, volume on 9. guitar volume wide open up to MOTSM, then varied. Resonance knob backed off a tad to take some of the ceramic edge off.

hear that tone change on the opening e string? very loose, probably from 100k/4 ohm NFB and/or 32uF PI can.

http://www.soundclick.com/player/single ... 39503&q=hi" onclick="window.open(this.href);return false;

Please comment. Lots of other goodies on the way. seems to be heading in the right direction but I want your input.

Cheers