Super Lead Tweaks - Unchained

[rgalpin]

First things first... the clip!
http://soundclick.com/share.cfm?id=11669102" onclick="window.open(this.href);return false;

How does that sound compared to the clips in the Hot Rails thread? I raised some filtering and went from .022 to .0022.
Clip from Hot Rails thread (before the change): http://soundclick.com/share.cfm?id=11664654" onclick="window.open(this.href);return false;

Ok - my plan is to use this thread to chronicle the evolution of this amp from where I found it - in the disarray of multiple half implemented tweaks and forays into semi misguided tone quests - into a better sounding amp and hopefully learn a bunch of stuff along the way. My plan is to end up with a MV amp that hopefully retains the SL mojo and allows me to operate without an attenuator. But... we'll see.

The baseline starting point is what i used in the Hot Rails thread:
http://soundclick.com/share.cfm?id=11664665" onclick="window.open(this.href);return false;

split cathode
V1b 2.7k/.68 --> .022
MIXER 470k/500p
v2a 820/.68
Tone stack 33k/500p
PI Couplers .1
NFB 68k, 8 ohm tap
FILTER CAPS
preamp - 50
screens - 25 (2 50+50s with the jumper lifted)
mains - 50
PI - 50
2 tubes EH6CA7 (2 outer tube sockets are empty)
Bias 25 @ 511V


OT - Mercury Magnetics Axiom 0100JM. Seems to be dated 5/03. ?? Almost vintage already haha!
PT - HTS 6010 (don't know what that is - anybody?)

ATTENUATOR - Weber Mass 150 on 4

CAB - 4x12 V30s - wired to 4 ohms (amp set at 8 ohms per Weber MASS 150 spec)

MIC - sm57 direct center of cone

GUITAR
body - fender - unknown wood, got it off ebay, pretty light
pup - hot rails bridge, all fender original grease bucket wiring and 250k pots
neck - mighty might rosewood top
trem - 6 screw fender
nut - all parts replacement nut (nylon?)

In the clip I'm posting here and now the following tweaks were made to the above spec:
.022 coupler was changed to .0022
25uf on the screens was upped to 50uf
50uf on PI was upped to 100uf

http://soundclick.com/share.cfm?id=11669102" onclick="window.open(this.href);return false;

The next thing I might do is lower the filtering in the pre amp - not sure I need to investigate a little on that - but I know some folks go as low as 16uf there - and I'm currently at 50.

[rgorke]

Rob,

From what you say you did, I would have expected a tight, sterile tone. To the contrary, I find the higher filtering brings a bit more clarity to the tone. How does it feel? Does it seem really tighter than the other clip? The chugging drop D on Unchained holds together great.

Nicely done, keep the clips coming..

[rgalpin]

Rob,

From what you say you did, I would have expected a tight, sterile tone. To the contrary, I find the higher filtering brings a bit more clarity to the tone. How does it feel? Does it seem really tighter than the other clip? The chugging drop D on Unchained holds together great.

Nicely done, keep the clips coming..

Agreed! Definitely holds together better. It was a little harder to play. When the filtering is lower (as it was before the tweak), it seems to create more gain in a way. Because it's sloppier and flows easier. But at a price: CLARITY! So, I'm thinking it's better to keep that stuff tight and find a better place to get gain. News for me! I've been using lower filter cap values for a long time.

[rgorke]

Rob,

From what you say you did, I would have expected a tight, sterile tone. To the contrary, I find the higher filtering brings a bit more clarity to the tone. How does it feel? Does it seem really tighter than the other clip? The chugging drop D on Unchained holds together great.

Nicely done, keep the clips coming..

Agreed! Definitely holds together better. It was a little harder to play. When the filtering is lower (as it was before the tweak), it seems to create more gain in a way. Because it's sloppier and flows easier. But at a price: CLARITY! So, I'm thinking it's better to keep that stuff tight and find a better place to get gain. News for me! I've been using lower filter cap values for a long time.

Remember when I got thos 16uf+16uf caps from you? Well, I had them in there for while the went back to the DF spec. For the gain and lows, I have have been using the analogy of a 300 lb Chris Farley or a 300 lb Ahnold S in this competition days. I think we really want the tight muscular gain than the soft flabby gain, no?

[rgalpin]

Absolutely. What is the DF spec for the preamp filtering?

[rgorke]

Absolutely. What is the DF spec for the preamp filtering?

2] 100uf's f&t in series mains
2] 32uf's f&t in series screens
1]100uf lcr phase inverter
1] dual 33 x 33 f&t preamp

[rgalpin]

I replaced the 50+50's with 100+100's on the mains but I now have a ground hum. I think I always had a ground hum but not this bad - now it's unplayable.

I was going to try and just play through it to see if I could hear a change in tone from the cap replacement - so i lifted the ground on the amp at the receptacle - when i put on the guitar, i felt a little pinch in the belly as the metal from the trem unit touched my stomach - i thought, "yeah, this is not safe."

where do i begin to look for the source of this problem? i'm thinking that SOMEWHERE something that is supposed to be going to ground (AC) is remaining in the signal... but where and how?

any help is greatly appreciated. THANKS!

[stef]

Interesting thread!

I'm using
mains 50 (daly)
screens 16 (f&t radial)
pre 32 + 32
pi 50 (or 100) daly

if i decided to go higher i'd bump screens to 32 and pi to 100 and wouldn't go higher than that with eh 6ca7's

IME the v30's sound darker but also tighter and cleaner than my 100watt cab..my amp sounds more distorted and looser with M's

[vh junkie]

Absolutely. What is the DF spec for the preamp filtering?

2] 100uf's f&t in series mains
2] 32uf's f&t in series screens
1]100uf lcr phase inverter
1] dual 33 x 33 f&t preamp

Did DF actually spec an F&T 33/33 for the preamp? I have found the F&Ts to muddy up the sound a bit.

I replaced the 50+50's with 100+100's on the mains but I now have a ground hum. I think I always had a ground hum but not this bad - now it's unplayable.

where do i begin to look for the source of this problem? i'm thinking that SOMEWHERE something that is supposed to be going to ground (AC) is remaining in the signal... but where and how?

Just replacing the caps should not have introduced a lot of hum (though if they needed forming there might be some effect there). Most likely you disturbed an existing ground somehow? Perhaps some pics?

[rgalpin]

Interesting thread!

I'm using
mains 50 (daly)
screens 16 (f&t radial)
pre 32 + 32
pi 50 (or 100) daly

if i decided to go higher i'd bump screens to 32 and pi to 100 and wouldn't go higher than that with eh 6ca7's

IME the v30's sound darker but also tighter and cleaner than my 100watt cab..my amp sounds more distorted and looser with M's

stef - you reminded me that i didn't include the tubes in my spec - i updated it - i'm using EH 6CA7s - only two of them - the outer 2 sockets are empty.

[rgalpin]

Just replacing the caps should not have introduced a lot of hum (though if they needed forming there might be some effect there). Most likely you disturbed an existing ground somehow? Perhaps some pics?

i'll get some pics - i went back and turned the amp on and carefully poked around with a pencil trying to find the source - i was able to make it hum to a lesser degree by moving some ground wires around the volume pot - but couldn't make it go away completely.

but i was able to play it - i am hear a truer color in the core tone - mostly noticeable when soloing - i am not able to turn it up to 10 without losing the integrity of the tone. i'll get a clip and some pics posted...

got to solve this hum issue though - it's a drag - my amps are always SILENT. i can't stand hum.

[vanhalen5150]

Larry grounds?

[rgorke]

Larry grounds?

It's an older amp, I would bet he doesn't. Some pics would be helpful.

[rgorke]

Absolutely. What is the DF spec for the preamp filtering?

2] 100uf's f&t in series mains
2] 32uf's f&t in series screens
1]100uf lcr phase inverter
1] dual 33 x 33 f&t preamp

Did DF actually spec an F&T 33/33 for the preamp? I have found the F&Ts to muddy up the sound a bit.

Just replacing the caps should not have introduced a lot of hum (though if they needed forming there might be some effect there). Most likely you disturbed an existing ground somehow? Perhaps some pics?

Yep, not sure if they were current production or older ones. Were f&ts around in the 60s/70s?

[rgalpin]

Here's a gut shot - partial. This was taken before I changed to .0022 - other than that all is the same.

What's a Larry ground?