S.I.R. 100W SuperLead Schematic pt. II

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sonoman1979
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by sonoman1979 » Fri Jun 30, 2017 1:07 am

Hi,
I want to share some things that I have learned. Since I'm not able to use the hot shield, I have try several capacitance values (one lead soldered directly to grid and the other one just after coupling cap, so there is no danger in case the capacitor fails), trying to emulate a shielded that goes from 33k input resistor to the grid of triode and shield connected to plate as mentioned by bmwfreq, I have try values from 5pF to more than 47pF and the way it alters tone and gain may vary with littlle changes, and about the best or correct value is difficult to say because all depends on what do you have in the rest of the gain stages. I finally decided to use a unique value (18pF), considering that I'm trying to emulate the effect of a shielded cable of 18cm (about 7 inches) that has 1pF per centimeter.

Another thing, I think that sometimes you may be very close to the tone you want, but your tone is too thin or too dark sounding, then you may vary the size fo the voltage divider resistors. For example, you are experimenting blocking distortion becouse there is too much low frequencies pronounced. One way to correct this would be to put a resistor across the potentiometer and adjust a little the gain with that pot, the smaller the resistor across the potentiometer the thinner the tone will be. In case you don't have a second potentiometer then you can use two potentiometer to fine tunning, once you have the values you want then replace them with resistor or combination of resistors, this may take some effort and time.
Note that for example 1M potentiometer with parallel 470K resistor, will be equivalent to a potentiometer of 320K in case you want to use two potentiometer to fine tune the resistor values of the voltage divider.
:thumbsup:

I think this is the best I can do with my JTM60, not excaltly AFD tone but I think I like this:

http://soundclick.com/share.cfm?id=13593454

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by BRMSlash » Tue Jul 18, 2017 6:36 pm

Tightened up the treble by replacing all the silver mica caps with X5F or C0G 1kV ceramics. Also changed all the cathode bypass caps to 250V MKT1813's, except for the 1st stage which is a 100V version. Replaced all the metal film resistors I had in the cathodes, except for one, with carbon films. Cathodes tweaked slightly to 3k3, 2k7, 10k, 1k2 in order from 1st stage to last stage.

http://sclk.co/s83jcl

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by snakepit86 » Fri Aug 04, 2017 7:37 pm

BRMSlash wrote:Tightened up the treble by replacing all the silver mica caps with X5F or C0G 1kV ceramics. Also changed all the cathode bypass caps to 250V MKT1813's, except for the 1st stage which is a 100V version. Replaced all the metal film resistors I had in the cathodes, except for one, with carbon films. Cathodes tweaked slightly to 3k3, 2k7, 10k, 1k2 in order from 1st stage to last stage.

http://sclk.co/s83jcl
about the MF resistors in the cathodes replaced by carbon, what do you want to reach?

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by BRMSlash » Mon Aug 07, 2017 6:20 pm

Too many metal film resistors made the treble too prominent & loose. The carbon films seemed to calm things down and give a more natural tone. I kept one metal film in the 2nd stage cathode partial bypass as it helped to maintain clarity (carbon filmed in this position was a bit thick sounding).

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by CoffeeTones » Mon Aug 07, 2017 11:09 pm

sonoman1979 wrote:
I think this is the best I can do with my JTM60, not excaltly AFD tone but I think I like this:

http://soundclick.com/share.cfm?id=13593454
Man this sounds really good. :thumbsup:

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by Roe » Sun Sep 10, 2017 11:08 am

The CAE3+ lead channel looks surprisingly similar to a #39 preamp: http://www.lordriffenstein.com/images/cae-3+.jpghttp://f.defaut.free.fr/perso/DIY/CAE%203_SE.bmp
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by sonoman1979 » Sun Sep 17, 2017 2:34 am

CoffeeTones wrote:
Mon Aug 07, 2017 11:09 pm
sonoman1979 wrote:
I think this is the best I can do with my JTM60, not excaltly AFD tone but I think I like this:

http://soundclick.com/share.cfm?id=13593454
Man this sounds really good. :thumbsup:
Thanks Duane, but I have to modify the amp again because I found a bad solder joint inside the control of my les paul, and after re-solder that, the pickups were giving more output and the tone of the amp was a mess :palm: . After a few weeks trying different values I think now is ok again, this is a new recording without any post eq or post reverb added, I really think that if I try this on a 4x12 cab will sound much better.

https://soundclick.com/share.cfm?id=13630821

:thumbsup:

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by CoffeeTones » Sun Sep 17, 2017 10:03 am

Yes, I agree with the 4 x 12 or even a 2 x 12 cab. Overall the sound is fine. It only needs to be thicker in the mids IMO. :thumbsup:

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by sonoman1979 » Tue Sep 19, 2017 3:52 am

CoffeeTones wrote:
Sun Sep 17, 2017 10:03 am
Yes, I agree with the 4 x 12 or even a 2 x 12 cab. Overall the sound is fine. It only needs to be thicker in the mids IMO. :thumbsup:
You're right Duane, do you think this one is better? Maybe I need to rest my ear a couple of days, sometimes fatigue makes hear things different. :scratch:

https://soundclick.com/share.cfm?id=13631564

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by CoffeeTones » Tue Sep 19, 2017 11:40 am

Fatigue can definitely get to be an issue. The mids have lost the right frequency, too squishy plus the gain is not right in that clip. If you could retain the gain and bite from the previous clips and push the mids a little, it would be there. A method I use, is trying many different value caps across the 4th stage 820R cathode. 10uF is great in my amps. 2.2uF works good to tighten bass but looses the mids I like. Below 2.2uF gets too thin for me. That cap increases gain very little but is a sensitive adjustment for tone because like the NFB, it can add or take away some nice character.

It could be just a matter of playing with the peaker caps or the treble cap in increments. If you already have 2.2nF // 470k (1nF // 470k can be nice there as well) before the volume pot and a 500pF treble cap, try 680pF or 1nF at the divider and see if it works for you. 1nF is impressive but may lose too much punch and harmonics in the highs. I recall the 1nF ceramic worked nicely bypassing the divider, 470k because the sound character of the ceramic cap retained the punch and bite in the highs. That amp had a 470k // 1nF befofe the volume pot too.

Ceramic caps can add kerrang sound and sizzle but are not for everyone's taste as they can be harsh in the highs. Mica caps sound clearer and do not have so much push in the upper mids / lower highs like the ceramic type produce. You have to find your preference in different locations but generally mica works best except for the bright cap and maybe bypassing the 470k before the volume pot and across the 470k divider.

If you have a bright cap at the volume pot, that value is critical. I always try every value between 120pF and 5nF. You will find your sweet spot but I usually like 120pF, 500pF or 3n3 with a 1 Meg pot.

Also toy around with the NFB resistor. Any value between 56k and 100k to your preference. I generally use 68k, 82k or 100k depending on how much thickness, looseness or tightness and kerrang sound I want when palm muting and such. Below 56k is where it starts to lose too much output. I usually stay with the 10k PI tail. 22k seems to work better for the #34 tone. 22k produces a thinner tone and can be fizzy sounding.

I'd also leave out or adjust the 150k from the volume pot to ground. Leaving it out makes the tone a little thicker for me.

The circuit used for the presence is a game changer as well. The circuit with the 5k pot sounds awesome. It is less buzzy and and thicker than the circuit with the 25k pot which is buzzy and thin sounding in comparison. In the 5k circuit, a 330nF cap works well. A 470nF cap works well in the 25k circuit. The larger value caps add some girth but allows you to still dial the glassy punch back in. Which sounds best in your amp is up to you. You are close enough to the tone, I'd stay with the presence circuit you have now and test the larger value cap in it.

Those things should be easy to test without much soldering.
Last edited by CoffeeTones on Wed Sep 20, 2017 2:57 pm, edited 7 times in total.

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by reychapa » Tue Sep 19, 2017 2:13 pm


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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by CoffeeTones » Tue Sep 19, 2017 2:25 pm

reychapa wrote:
Tue Sep 19, 2017 2:13 pm
[youtube]https://www.youtube.com/watch?v=T-jxZbkWVrE[/youtube]

:D
LOL, I remember when you first jumped into this thread. The amp sounds cool.

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by reychapa » Tue Sep 19, 2017 2:42 pm

Thanks too much to you I found my tone, now that I have a better sample of audio, I share with you this video!...

:thumbsup:

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by sonoman1979 » Tue Sep 19, 2017 5:51 pm

CoffeeTones wrote:
Tue Sep 19, 2017 11:40 am
Fatigue can definitely get to be an issue. The mids have lost the right frequency, too squishy plus the gain is not right in that clip. If you could retain the gain and bite from the previous clips and push the mids a little, it would be there. A method I use, is trying many different value caps across the 4th stage 820R cathode. 10uF is great in my amps. 2.2uF works good to tighten bass but looses the mids I like. Below 2.2uF gets too thin for me. That cap increases gain very little but is a sensitive adjustment for tone because like the NFB, it can add or take away some nice character.....
Thanks Duane, Also could be two things, in the second recording I removed 150pf anode bypass capacitor that I had on 3rd stage and also raise the gain pot to 7.5 (and in the first recording I'm not so sure but I think it was on 6), I will try some other values then. Thank you :thumbsup:

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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by Roe » Fri Sep 22, 2017 3:22 am

Roe wrote:
Sun Sep 10, 2017 11:08 am
The CAE3+ lead channel looks surprisingly similar to a #39 preamp: http://www.lordriffenstein.com/images/cae-3+.jpghttp://f.defaut.free.fr/perso/DIY/CAE%203_SE.bmp
Any comments on this? the typology of the CAE is very similar but the voicing may me somewhat different?
http://www.myspace.com/20bonesband" onclick="window.open(this.href);return false;
http://www.myspace.com/prostitutes" onclick="window.open(this.href);return false;
Super 100 amps: 1202-119 & 1202-84
JTM45 RS OT JTM50 JMP50 1959/2203/34/39

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