Crackatwoa Upgrades

hpjun · 7079

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Offline hpjun

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Reply #15 on: September 04, 2016, 08:32:10 AM
Thanks!

I think that might be it for the available upgrades. Something else I thought of was shielding the signal wires all the way from input to output, probably with mu metal shielding sheets. I would probably shield the power supply as well if I get it.

I ordered a 7802 Tung-Sol it should drop to impedance from 120 ohms to 42 ohms according to my calculations. 42 ohm out into 350 ohm sennheisers has about a damping factor of 8 which is really ideal, it could probably drive medium impedance headphones although not with a 47 uf output cap.

I also ordered the 47 UF Obbligato Gold Premium Film caps.

I also want to TwoQuiet attuenator but it's expensive. I do like the L/R balance control and the stepped attuenator removes that.

Jun


Offline Paul Birkeland

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Reply #16 on: September 05, 2016, 05:50:25 AM
Thanks!
I think that might be it for the available upgrades. Something else I thought of was shielding the signal wires all the way from input to output, probably with mu metal shielding sheets. I would probably shield the power supply as well if I get it.
Again, you're fixing a problem that doesn't exist by adding expensive metal sheets that can come loose and cause damage to your amplifier.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline davve34

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Reply #17 on: October 27, 2021, 06:05:31 AM
Is it worth adding chokes on the crackatwoa and the discrete bridge rectifier? Or the shunt power supply cleans the power too?
 



Offline Paul Birkeland

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Reply #18 on: October 27, 2021, 06:14:08 AM
A choke is pretty pointless in the Crack-a-two-a.  You would be attempting to remove power supply ripple that won't make it through the shunt regulator, and in the process you'll be adding an extra source of magnetic noise that wouldn't otherwise be there. 

The Cree bridge won't hurt anything if you wanted to add that.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man