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

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

Post by bmwfreq » Thu Jul 26, 2018 9:43 pm

So, the 4.7K is grounded. The NFB resistor has continuity to ground where the wire meets the 100K resistor. I think that’s to be expected, no?
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by CoffeeTones » Thu Jul 26, 2018 10:53 pm

Check the tail and 470R really well. You should have 4k7 plus whatever tail value you have when probing from ground to where the 470R and tail meet. Then make sure the 470R value is right and not a 470k. The 100k NFB won't read 100k in the circuit but you should get a reading when probing where the 100k NFB connects to the 4k7 and the output jack or impedance switch.

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

Post by bmwfreq » Fri Jul 27, 2018 10:18 am

I’m seeing 26K where the 22K tail resistor meets the 470K resistor on pins 3 and 8 of the PPI. Reading with reference to ground.

So, 22K plus 4.7K equals...26K.
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[ ..... ]
| O O |
| O O |

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

Post by CoffeeTones » Fri Jul 27, 2018 12:36 pm

That resistor connected to pins 8 & 3 is supposed to be 470 ohms, not 470k.

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

Post by bmwfreq » Fri Jul 27, 2018 2:10 pm

Damn, Coffee!!! You are correct!!! I’m gonna change the resistor and get back to ya...
——————————————————————————
Well, that was it! Couldn’t see the Forrest through the trees. I can’t believe I couldn’t see that.

Thanks for the help, Coffee!!! I really appreciate it!! I wouldn’t have noticed that for a long time.

This is gonna sound stupid but...do you drink Starbuck’s coffee, Coffee??
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[ ..... ]
| O O |
| O O |

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

Post by bmwfreq » Fri Jul 27, 2018 2:13 pm

If so, are you still at 620?
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[ ..... ]
| O O |
| O O |

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

Post by CoffeeTones » Fri Jul 27, 2018 3:07 pm

bmwfreq wrote:
Fri Jul 27, 2018 2:10 pm
Damn, Coffee!!! You are correct!!! I’m gonna change the resistor and get back to ya...
——————————————————————————
Well, that was it! Couldn’t see the Forrest through the trees. I can’t believe I couldn’t see that.

Thanks for the help, Coffee!!! I really appreciate it!! I wouldn’t have noticed that for a long time.

This is gonna sound stupid but...do you drink Starbuck’s coffee, Coffee??
Glad we found the problem.

I did drink Starbucks for years until I found a coffee that tastes better, is cheaper and takes less to make the same size cup. That made it a win, win. I still go to Starbucks when I'm on road trips.

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

Post by CoffeeTones » Fri Jul 27, 2018 3:10 pm

bmwfreq wrote:
Fri Jul 27, 2018 2:13 pm
If so, are you still at 620?
Yes Sir.

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

Post by bmwfreq » Fri Jul 27, 2018 9:07 pm

:toast:

Great!!

Thanks again, Coffee!!! I really appreciate 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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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by dukeamps » Mon Aug 13, 2018 10:20 am


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

Post by BRMSlash » Tue Aug 21, 2018 7:10 am

Lowered the 1st stage coupling cap to 2n2. Changed the phase inverter 100n cap from a TAD Mustard to a CDE WMF 400V. Changed the Presence cap from a TAD Mustard to a CDE 225P 400V.

http://sclk.co/s875u9

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

Post by CoffeeTones » Tue Aug 21, 2018 10:24 am

22k tail? If so, that combo might be better with 10k - 20k tail. That or replace a ceramic cap with mica as fizz cap or in another position. I remember you liked the ceramics though. The clip sounds good, just a little strident in the top end. I changed my amp from original Sozos to Mojo Dijon caps - they seem more direct sounding in the mids and top end. Bottom end is about the same and mids seem less smeared. The Mojos are slightly more modern sounding.

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

Post by CoffeeTones » Tue Aug 21, 2018 10:36 am

bmwfreq wrote:
Fri Jul 27, 2018 9:07 pm
:toast:

Great!!

Thanks again, Coffee!!! I really appreciate it!!
Thanks for the mail :toast:

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

Post by bmwfreq » Tue Aug 21, 2018 2:08 pm

You bet!!! Wish it could have been more!!

Thanks for fixing my stupid mistake!!

Thanks again for your help.

Enjoy!!!
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[ ..... ]
| O O |
| O O |

User avatar
bmwfreq
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Posts: 524
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Re: S.I.R. 100W SuperLead Schematic pt. II

Post by bmwfreq » Tue Aug 21, 2018 2:12 pm

Just a foot note for everyone here.

I replaced all of the resistors in my amp with 1% metal film resistors. Amp sounds awesome!!! Much more growl but...not very 34ish.

Going back to carbon comp.

When will I learn that if it ain’t broken...DON’T FIX IT!!! :palm:
1984 2203 JCM 800
(#34 mod)
1960AV 4x12
2x12 25 watt Greenbacks
2x12 Vintage 30's
[ ..... ]
| O O |
| O O |

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