70's Build

[David Root]

I'm currently tweaking my #124 build and +1 on the black plates and 7025s! In order to get the right voltages I ended up with a '70 Amperex 7025 in V1, a '60s grayplate RCA in V2 and a '62 Tungsol long wide plates in V3.

Cleans are really nice, still have artifacts on the OD like Tony says, maybe I should take out the 10ufs on V1 and change to 5 uFs?

Just shows you that there really is a lineage here!

[angelodp]

David, please elaborate on the artifacts. High end stuff?

ange

[bluesfendermanblues]

I'm currently tweaking my #124 build and +1 on the black plates and 7025s! In order to get the right voltages I ended up with a '70 Amperex 7025 in V1, a '60s grayplate RCA in V2 and a '62 Tungsol long wide plates in V3.

Cleans are really nice, still have artifacts on the OD like Tony says, maybe I should take out the 10ufs on V1 and change to 5 uFs?

Just shows you that there really is a lineage here!

Depends on what you are trying to achieve....my #124 clone (which is build on a Ceriatone OTS) came to life with
- 22uf on V1a and V1b, and 5uf on V2 (maybe because I play mainly strats/tele)
- larger snubber 470pf on V2b
- a 250k drive pot and
- a treble bleed (0.001 uf with a 500k trim).
- The OD trim (100k i my amp) is set pretty low aound 15k to ground.
- A 345k trim like the original, would also help shave off some nasty high frequencies.

[bluesfendermanblues]

In order to get the right voltages I ended up with a '70 Amperex 7025 in V1, a '60s grayplate RCA in V2 and a '62 Tungsol long wide plates in V3.

I would probably adjust the dropping string to get the same result.

Tried a lot of ol' (used) tubes (GE7025, Mullard, Brimer and Siemens) in my D clone, but never found them superior to JJ ECC83S.

[David Root]

All, thanx for your responses. "Artifacts" I take to be the high end trash that seems to ride on the basic note and sounds quite distinct and separate, almost like the string is loose in the nut slot. What some folks call fizz, I believe.

I changed the snubbers from ceramic to polystyrene, (270 pF), made no difference. I can try higher values in either type. The OD entrance trimpot is only 310K, I have considered adding a 33K to ground to get close to 345K, but have not done it yet, ran out of time yesterday.

I am also considering something along the lines of the "Funky OD Entrance" on #40, to drop some highs before they get into the OD circuit, maybe just a simple bleed to ground in the same spot, although I see most people put the bleed on the other end of the OD circuit.

There is no fizz/artifacts on the clean channel going in so I would assume they are being generated inside the OD circuit. Does cutting the highs going in help? That would depend on how the artifacts are generated I think.

I should have mentioned I am tweaking for a Les Paul type guitar (Epi Elitist 57 Goldtop w/old '65 SG HBs in it).

[bluesfendermanblues]

It might be better to trim off the exces treble at the output of the OD...either by increasing snubber on Vb2 and/or via a treble bleed.

IME the capacitor material (ceramic, mica or poly) makes no difference for snubbers or treble bleeds, which only grounds treble frequencies.
The are not tone caps like, bright caps, tone stack caps etc.

Some people will pay top dollar fo 'bumble bee' capacitors in their Les Paul for the tone controls, which are also in essence treble bleed. Although with much lower cutoff frequencies. Kind of silly IMO

[marcos]

Hi David,
in my experience the "Funky OD entrance" will actually make the OD more fuzzy.I guess reducing the "artifacts" is achieved by carefully adjusting the OD trim and OD gain controls, I am quite familiar with this
problem, used to drive me crazy, as I don´t like too much distortion myself.
Increasing the snubbers beyond a certain point will not help,
it will just make the artifacts darker sounding
I would definetely prefer cutting the highs after the OD,
if done tastefully it can smooth out the OD tone.
One thing I have noticed is that the snubbers or the treble bleed do affect the clean tone as well, although I have no explanation for this phenomenon.
Another reason to keep the snubbers as small as possible.
I agree, it doesn´t make a lot of difference if you use ceramic or other
caps, more a matter of taste, really.
Just my 2 cents Marcos

[bluesfendermanblues]

One thing I have noticed is that the snubbers or the treble bleed do affect the clean tone as well, although I have no explanation for this phenomenon.
Marcos

Marcos, you must have your OD relay wired diffferent than mine.
In clean mode my OD is completely out of the circuit so neither snubbers nor treble bleed affect my clean tone at all.

Maybe you could post a picture?

[marcos]

Bluesfendermanblues,
you are right, my relay is wired as in the #40 schematic,
where the OD input is not grounded when in clean mode.
I´ll have to look into this some time soon, never thought of this.Thanks for your contribution Marcos

[talbany]

Bluesfendermanblues,
you are right, my relay is wired as in the #40 schematic,
where the OD input is not grounded when in clean mode.
I´ll have to look into this some time soon, never thought of this.Thanks for your contribution Marcos

Marcos
I noticed this as well and thought there might be some bleed over(Noise) so I wired my #13 like the later 80's and works fine if you want to go there
I don't really get the fizz in my 70's build at all and didn't use snubbers either..I can't say for certain that the Carbon comps in the OD path helped but can say they didn't hurt..

Tony

[marcos]

Thanks for the input, guys.
This sounds promising, I´ll report back when I´m done,
although it will be some time until I find time to get into this.

Marcos

[bluesfendermanblues]

Bluesfendermanblues,
you are right, my relay is wired as in the #40 schematic,
where the OD input is not grounded when in clean mode.
I´ll have to look into this some time soon, never thought of this.Thanks for your contribution Marcos

Anytime. Marcos

[talbany]

Marcos

Glad to help as well and thanks again for all your help.

70's Models ROCK!!

Tony

[David Root]

Thanx to all, I will be trying your suggestions.

[marcos]

Hi guys,
it´s been a while since we discussed this.
I finally got around to trying the 80s style wiring for the OD relay,
on my 70s amp.
Grounding the OD input resulted in a very noticable improvement
of the clean tone, more open, more "fragile harmonics".
Another lesson learned, thanks to Bluesfendermanblues and Tony for pointing this out to me.

Marcos