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

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

Post by CoffeeTones » Sat May 06, 2023 12:04 pm

RG58 - appears to be solid instead of stranded core conductor, 22 AWG. .195" diameter, about 31pF per foot, high working voltage rated, insulation is not great and will melt easily if heat applied too long. I'd try to seek out some coax with Tefzel or Teflon insulation, tinned and stranded copper core 22 - 20 AWG. You assume the risk. If you choose to do the mod, do it as best and safely as possible.

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

Post by Antonio » Sat May 06, 2023 7:07 pm

CoffeeTones wrote:
Sat May 06, 2023 12:04 pm
RG58 - appears to be solid instead of stranded core conductor, 22 AWG. .195" diameter, about 31pF per foot, high working voltage rated, insulation is not great and will melt easily if heat applied too long. I'd try to seek out some coax with Tefzel or Teflon insulation, tinned and stranded copper core 22 - 20 AWG. You assume the risk. If you choose to do the mod, do it as best and safely as possible.
Thanks for the heads up, Coffee!

Here in Brazil there is no suitable cable for hot shield.

I'm thinking of asking a friend to bring this cable from Europe, it looks good!

https://www.tube-town.net/ttstore/coaxi ... g-187.html

What do you think of this one?

Thank you so much!
Gibson Les Paul 1959 R9 "Jessica"
SIR #34/#36 Amp Replica

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

Post by CoffeeTones » Sun May 07, 2023 9:57 am

The capacitance per foot is low, so you would need to use one foot to get about 20pF for the hot shield effect IMO.

Your linked description doesn't make clear the material of the center conductor (Staku stranded wire). From random data sheets, RG187 appears to be plated steel, stranded center conductor. Tinned or silver plated, pure copper is preferred IMO.

32 - 36pF per foot is better since you really shouldn't need a one foot piece from input to V1. (6 - 8 inches would provide about 18 - 24pF).

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

Post by Antonio » Sun May 07, 2023 7:46 pm

CoffeeTones wrote:
Sun May 07, 2023 9:57 am
The capacitance per foot is low, so you would need to use one foot to get about 20pF for the hot shield effect IMO.

Your linked description doesn't make clear the material of the center conductor (Staku stranded wire). From random data sheets, RG187 appears to be plated steel, stranded center conductor. Tinned or silver plated, pure copper is preferred IMO.

32 - 36pF per foot is better since you really shouldn't need a one foot piece from input to V1. (6 - 8 inches would provide about 18 - 24pF).
Great to hear that, Coffee!

I'm going to look for a cable that meets those specifications you gave me.

Thank you very much!
Gibson Les Paul 1959 R9 "Jessica"
SIR #34/#36 Amp Replica

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

Post by blacklabel » Mon Jul 17, 2023 12:02 pm

Hi guys, it's been a while since I've been back here, lately I've only played on mesa mk III and V :hairband:

I would like to ask you: has anyone recorded any new takes of #34?

I would like to play it again and it would be nice to have someone to talk to (miked sound only)

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

Post by dukeamps » Wed Sep 06, 2023 9:40 am


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

Post by dukeamps » Sun Sep 17, 2023 12:44 pm


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

Post by CoffeeTones » Sun Sep 17, 2023 12:50 pm

Are you posting the spec? :hide:

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

Post by dukeamps » Sun Sep 17, 2023 12:52 pm

CoffeeTones wrote:
Sun Sep 17, 2023 12:50 pm
Are you posting the spec? LOL :lol:
it was something like 4 10ks and something else, oh yes a 47p bright lol

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

Post by CoffeeTones » Sun Sep 17, 2023 12:52 pm

This fall weather is bringing back the amp fever! :scratch:

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

Post by dukeamps » Sun Sep 17, 2023 12:56 pm

CoffeeTones wrote:
Sun Sep 17, 2023 12:52 pm
This fall weather is bringing back the amp fever! :scratch:
I just might fire up the soldering iron again too lol

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

Post by dukeamps » Thu Oct 26, 2023 2:50 am

Last edited by dukeamps on Thu Oct 26, 2023 3:53 am, edited 1 time in total.

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

Post by dukeamps » Thu Oct 26, 2023 3:52 am


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

Post by CoffeeTones » Thu Oct 26, 2023 7:10 am

Man, that's the wrong angle for a gut shot. :lol:

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

Post by dukeamps » Thu Oct 26, 2023 7:22 am


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