Dogears...

[Funkalicousgroove]

I've been using 225P's on the recommendation from David Allen (Allen Amps) that they sound like 6PS, and liked them much. I find 715/716 a bit too high-FI with a grainy top end, and I find M150's Muddy in these. FWIW I've just rec'd a bunch of 6PS OD's for my next builds. From what I understand they're the exact same caps as the Mallory PVC series used by Ken Fischer in Trainwrecks and Mike Soldano in SLO's.

[dogears]

And maybe the exact same ones used in many many of the grail Dumbles???

FWIW I've just rec'd a bunch of 6PS OD's for my next builds. From what I understand they're the exact same caps as the Mallory PVC series used by Ken Fischer in Trainwrecks and Mike Soldano in SLO's.

[Funkalicousgroove]

I thought that was a given!!!

[Icetech]

Mouser rocks:) Ordered the parts less than 24 hours ago... from texas to detroit... and they are here:) and i ordered em 2nd day:)

[Icetech]

Ok dog, i wouldn't believe it if i didnt hear it for myself... replaced all the caps in the amp with ceramics and 715's.. and the resistors you said with viashay/dales...

Its not perfect.. by far.. BUT its nearly silent now... even cranked i dont even really hear a hiss...

The notes are fuller sounding. and not just that, before i always thought the mid notes were kinda... missing for lack of a better word.. like there was supposed to be more, hard to explain..

Its not as pretty (and yes that was my nicest attempt:)) but heres some pics now...

http://mywebpages.comcast.net/roadrebel ... mpleft.jpg
http://mywebpages.comcast.net/roadrebel ... pright.jpg

BTW.. everyones bench a mess?

http://mywebpages.comcast.net/roadrebel/amp/bench.jpg

[Bob-I]

The notes are fuller sounding. and not just that, before i always thought the mid notes were kinda... missing for lack of a better word.. like there was supposed to be more, hard to explain..

This is what I like to call "complexity".

Does is seem to you that more frequencies are being represented in the sound?

Its not as pretty (and yes that was my nicest attempt:)) but heres some pics now...

http://mywebpages.comcast.net/roadrebel ... mpleft.jpg
http://mywebpages.comcast.net/roadrebel ... pright.jpg

BTW.. everyones bench a mess?

http://mywebpages.comcast.net/roadrebel/amp/bench.jpg

I see you replaced the screen resistors too, great.

BTW, I purposly crop all the pics of my amps to avoid showing my bench, yes it's just as bad.

[Icetech]

Yeah, i need to get some more of the drawer organizers.. that one i have holds bout half the resistors, thus he bags all over the place:)

Don't know about complex, but yeah on the more freq's, its like before i would place a chord and it was just missing alot, almost like the notes were being ran through a filter (which i guess they kinda are) and alot was being left behind...

I only got to play for a few minutes last night, but the gain channel is totally different, seems to have lost bass, and has less crunch to it, and i have that cap discharge thing back.. its a much clearer noise on the notes though:)

[dogears]

Hi Icetech,

Try raising the 150k series resistor to a 180k, the one following the .0047uf OD2 cap. That should restore the bass. You could also try adding another .2uf to the CL2 bypass. Maybe just make a total of 1.5uf

Turn the gain trimmer up a hair to get the gain back.

Try and get 200v on the V1 and V2 tubes......


Glad it is progressing!

[Bob-I]

Don't know about complex, but yeah on the more freq's, its like before i would place a chord and it was just missing alot, almost like the notes were being ran through a filter (which i guess they kinda are) and alot was being left behind...

I understand, that's what I call midrange complexity. If I'm wrong so what.

I only got to play for a few minutes last night, but the gain channel is totally different, seems to have lost bass, and has less crunch to it, and i have that cap discharge thing back.. its a much clearer noise on the notes though:)

I'd doubt if you really lost bass as much as you gained treble and the balance seems off. Follow Scott's suggestions, you'll get the balance back.

The gain may be a tad less because of poor tolerance in the old resistors. I had the same thing and checked the resistors, they were all close to 10% off, even though they were 5% resistors. I just opened up the trim a tad.

Do you have a recording rig? If yes post a short clip, could be a big help.

[Icetech]

No.. i am scanning ebay for a sm57:)

I am gonna start tweaking this weekend, just wanted to get a good baseline right now...

My V1 a-b are 191v and 194v right now...

Low gain isn't really a issue.. its the "texture" of the gain... i just need to play with it more is all... i can go from clean clean to insane yngwie gain no problem, wondering if a post od stack is in order:)

BUT i will say this.... clean channel.. master allt he way up.. preamp on bout 6-7.. with hot humbuckers and the thing sounds simply amazing.... great touch control.... goes from a light break up to good and nasty depending on attack:)

Will keep ya posted on progress...

P.S. i HATE that 22k into 100k with a 250pf and a 470k riding over it all network thingy.... HATE... thats why its so damn ugly:) too tight to solder for my skills

[Icetech]

Dog, or anyone really.. I did your mods you gave me, amp sounds good.. but i have been chasing a problem, with the preamp over bout 4, if i attack hard at all, anythuing above a soft single string hit really, i get a crunchy sound like a cap bleeding off, Bob called it Ghosting, so i started unsoldering some things like snubbers, that 22m/.1 cap thing on v1b, and trying the amp after each change.... finally i unsoldered the NFB wire from the 4.7k resistor.. and bam... Clean.. no more fuzz.. amp sounds better than any amp i have owned... But with the NFB unsoldered i have a THUMP THUMP.. like a heartbeat.. but erractic, i checked 3 layouts to make sure i had it right and it wasn't a mistake ont he one i was using...

Is there a problem with NFB and bassman transformers or something? any ideas?

And that 4.7k goes to the output jack yes? i checked one of bobs pics and it showed it going to the impedence selector.. but i dont have one.. so i have it run right to the output jack where the wire from the OT hooks in...

Thanks...

[dogears]

Shouldn't V1B have 44M and a .047???

I think maybe your output has bad oscillations. I think I read about your issue on Aikens site. If I recall, removing the NFB fixes it. But, you then have the issue of no NFB!

Maybe it is time for a replacement tranny.....

Dog, or anyone really.. I did your mods you gave me, amp sounds good.. but i have been chasing a problem, with the preamp over bout 4, if i attack hard at all, anythuing above a soft single string hit really, i get a crunchy sound like a cap bleeding off, Bob called it Ghosting, so i started unsoldering some things like snubbers, that 22m/.1 cap thing on v1b, and trying the amp after each change.... finally i unsoldered the NFB wire from the 4.7k resistor.. and bam... Clean.. no more fuzz.. amp sounds better than any amp i have owned... But with the NFB unsoldered i have a THUMP THUMP.. like a heartbeat.. but erractic, i checked 3 layouts to make sure i had it right and it wasn't a mistake ont he one i was using...

Is there a problem with NFB and bassman transformers or something? any ideas?

And that 4.7k goes to the output jack yes? i checked one of bobs pics and it showed it going to the impedence selector.. but i dont have one.. so i have it run right to the output jack where the wire from the OT hooks in...

Thanks...

[Icetech]

The issue with replacing a trannie.. is cost:) i have pizza to buy damnit!

Actually...i dont mind it without the NFB, cept the thump thump thump... Was hoping that this might have been a common problem that was known, and changing that 4.7k to something else would fix it:)

[Icetech]

Actually.. thanks for mentioning aiken.. his page has soem VERY good info in there....

Now that i understand what NFB does.. i see why i want it.. thinking of putting a 10k trimmer there and adjusting to see if i can get rid of the ghosting and keep NFB intact...

[dogears]

Try a 47pf cap across the PI. Just like good ole Fender used to do! Snubber cap for oscillations. Also, raisng the output grids a little may help.