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

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pjoliver182
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by pjoliver182 » Wed Jun 07, 2017 1:56 pm

bmwfreq wrote:...why would Santiago, Marshall or Slash care, when they never attempted to emulate the #34 in the AFD100 (this is a direct quote from Santiago himself.)
I re-read all of Santiago's posts again the other day and I believe he said that whilst the #36 mode of AFD1O0 was a circuit to achieve the tone of AFD but not the original mod...he promised that the #34 mode was exact.

"In fact I can 100% assure you that the AFD100 in #34 mode is the same amp as Slash has been playing."

viewtopic.php?f=3&t=29759&p=322531&hili ... go#p322531

In any case...well done for spotting the missing 4k7!

:toast:

gibsonclassic2001
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by gibsonclassic2001 » Thu Jun 08, 2017 4:38 am

Problem with afd100 is that we need to verifierad all weird values on that amp IRL.

Lke that 47k resistor that say 470k.
Typo from Marshall? :)

pjoliver182
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by pjoliver182 » Thu Jun 08, 2017 5:55 am

gibsonclassic2001 wrote:Problem with afd100 is that we need to verifierad all weird values on that amp IRL.

Lke that 47k resistor that say 470k.
Typo from Marshall? :)
Marshall don't make mistakes... :lol:

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

Post by sonoman1979 » Sat Jun 10, 2017 11:50 am

I don't see any hot shield in AFD100 schematic.

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

Post by herbvis » Sat Jun 10, 2017 11:59 am

If i remember correctly, they used the cap from plate to cathode method instead of the hot shield method.

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

Post by bmwfreq » Sun Jun 11, 2017 8:42 pm

Santiago told me that he used the paralleled preamp tube in the V7 position I believe it was (the first preamp socket on the AFD100 schematic) to help reproduce the effect of the hot-shield. The cap alone will never emulate the effect of a hot-shield... The hot-shield is producing a reactive type capacitance that you will never get with the 220pF cap.

If find the email, I will post it.
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[..... ..]
| O O |
| O O |

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

Post by bmwfreq » Sun Jun 11, 2017 8:55 pm

Roe wrote:removing the 4k7 will increase the NFB. Removing the 1m isn't a good idea, although you might try 2m2 instead for a slightly brighter and hotter signal (it is similar to increasing the value of the volume pot in your guitar if you plug straight into the amp)
Interesting. I'll give this a try and let you know what I think. Thanks for the input. As far as removing the 1M resistor goes, what affect would this have on the amp tone? I can't imagine it would be a good one.

As far as the 4.7K presence resistor is concerned, if it's there and I just can't see it, please let me know. I don't want to be misleading people. But as far as I can tell by enlarging and enhancing the AFD100 pics of the #34 that I have, it's apparent to me that the Presence resistor is in fact gone. Someone lately also told me that they do not see the 150K resistor on the preamp pot either. But if my memory serves me right, I thought someone at some point posted a pic here with the 150K preamp pot resistor visible...does anyone know for sure???
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[..... ..]
| O O |
| O O |

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

Post by sonoman1979 » Thu Jun 15, 2017 6:44 pm

bmwfreq wrote:Santiago told me that he used the paralleled preamp tube in the V7 position I believe it was (the first preamp socket on the AFD100 schematic) to help reproduce the effect of the hot-shield. The cap alone will never emulate the effect of a hot-shield... The hot-shield is producing a reactive type capacitance that you will never get with the 220pF cap.

If find the email, I will post it.
Interesting, I remember reading somewhere that parallel tubes increase Miller capacitance.

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

Post by bmwfreq » Thu Jun 15, 2017 7:20 pm

sonoman1979 wrote:
bmwfreq wrote:Santiago told me that he used the paralleled preamp tube in the V7 position I believe it was (the first preamp socket on the AFD100 schematic) to help reproduce the effect of the hot-shield. The cap alone will never emulate the effect of a hot-shield... The hot-shield is producing a reactive type capacitance that you will never get with the 220pF cap.

If find the email, I will post it.
Interesting, I remember reading somewhere that parallel tubes increase Miller capacitance.
That's it exactly. I think this is what Santiago tried to explain to me, but in a more detailed electronic engineer kind of way. Now if he had merely said what you said, I would have understood more clearly.

Based on the tone of the AFD100, I would have to say that the parallel preamp configuration must work, because if you take a JCM 800 with the #34 mod and you don't use the hot-shield method, the mod result is nothing without it.

Has anyone tried the "correct" hot-shield method in their amp yet?? What I mean by the "correct" hot-shield method is, the 33K resistor is mounted to the hi input jack with the shield on pin 6 and the center wire on pin 7 (or pins 1 and 2 if you have a horizontal input JCM.)

I tried this with my amp, and I have to say, it doesn't cut the sonic mustard. While this method did produce some "wah" effect, it is nothing like it is when the 33K resistor is mounted to the preamp socket. My question is, if Slash's #34 is configured this way, it shouldn't sound as good as it does.

Any thoughts on this from anyone??
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[..... ..]
| O O |
| O O |

bulldozer1984
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by bulldozer1984 » Mon Jun 19, 2017 2:08 am

I love the sound of this mod. Here is my amp.. Just messing around.. Don't worry its not just SCOM haha

https://soundcloud.com/bulldozer1984/2204-afd-mod

pjoliver182
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by pjoliver182 » Mon Jun 19, 2017 8:47 am

I think you may well be right about the 4k7 resistor. There's a good chance it was a mistake from the factory. There could be other errors that made this amp slightly different.

My '79 superbass had a 1meg mid pot...a 4k3 presence resistor...V2 preamp socket was wired incorrectly...

I honestly can't see any details of the preamp pot in the videos though...

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

Post by Unique » Sat Jun 24, 2017 10:55 am

pjoliver182 wrote:I honestly can't see any details of the preamp pot in the videos though...
Hey guys,

If you go to 'part 2' of the AFD100 investigation videos, and at the :13 mark they show that whole side of the chassis with the inputs, Pre-Amp Vol, Master, Treble, ect... I've taken a still shot of this and zoomed in on the Pre-Amp volume pot and enhanced it with a little color and brightness and there is no 150k resistor on the Pre-Amp volume pot. What I see is the green wire going up to the center lug on the Pre-Amp pot, which happens to have a burn mark on it shaped like a peanut. It is this burn mark that people are mistaking for the 150k resistor. Frank even pointed this out in that pic of #34 where he marked #34 mod components as being the 150k resistor. But that is not a resistor. You can actually see the green from the wire surrounding this burn mark on all edges and connecting to the center lug.

Here's the thing, Santiago has also included a 150k resistor on the #34 schem, so if it's not on the pot itself, then where is it?

Here is a pic of #34's Pre-Amp volume pot zoomed in and enhanced with a little color and brightness, you can judge for yourselves. I would like to hear your thoughts on this, do you see a 150k resistor here?

https://drive.google.com/file/d/0ByHqEL ... sp=sharing

*Edit: Here is another shot zoomed out a little further:

https://drive.google.com/file/d/0ByHqEL ... sp=sharing

bulldozer1984
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by bulldozer1984 » Sun Jun 25, 2017 2:41 am

Unique wrote:
pjoliver182 wrote:I honestly can't see any details of the preamp pot in the videos though...
Hey guys,

If you go to 'part 2' of the AFD100 investigation videos, and at the :13 mark they show that whole side of the chassis with the inputs, Pre-Amp Vol, Master, Treble, ect... I've taken a still shot of this and zoomed in on the Pre-Amp volume pot and enhanced it with a little color and brightness and there is no 150k resistor on the Pre-Amp volume pot. What I see is the green wire going up to the center lug on the Pre-Amp pot, which happens to have a burn mark on it shaped like a peanut. It is this burn mark that people are mistaking for the 150k resistor. Frank even pointed this out in that pic of #34 where he marked #34 mod components as being the 150k resistor. But that is not a resistor. You can actually see the green from the wire surrounding this burn mark on all edges and connecting to the center lug.

Here's the thing, Santiago has also included a 150k resistor on the #34 schem, so if it's not on the pot itself, then where is it?

Here is a pic of #34's Pre-Amp volume pot zoomed in and enhanced with a little color and brightness, you can judge for yourselves. I would like to hear your thoughts on this, do you see a 150k resistor here?

https://drive.google.com/file/d/0ByHqEL ... sp=sharing

*Edit: Here is another shot zoomed out a little further:

https://drive.google.com/file/d/0ByHqEL ... sp=sharing
It's on the schematic so he probably just put the 150k shunt resistor on the board. If I was designing a fresh build that's what I would do. I wouldn't hang shit off pots etc.

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

Post by Unique » Sun Jun 25, 2017 12:43 pm

bulldozer1984 wrote:It's on the schematic so he probably just put the 150k shunt resistor on the board. If I was designing a fresh build that's what I would do. I wouldn't hang shit off pots etc.
I don't see it there either. Anyone else see it on #34's board anywhere, or anywhere else as far as that goes?

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

Post by herbvis » Sun Jun 25, 2017 1:37 pm

https://www.boss.info/us/products/rv-500/
Looks like they finally did it. This has the srv2000 built in.

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