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April 19, 2019, 09:21:42 am

Author Topic: Tube Rolling w/Crack  (Read 436153 times)

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Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #1935 on: April 16, 2019, 05:38:59 pm »
Gracious, when did the 6F8G get so expensive?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Tom-s

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Re: Tube Rolling w/Crack
« Reply #1936 on: April 16, 2019, 10:58:04 pm »
How could i rebuild my Crack to work with this tube? http://tdsl.duncanamps.com/pdf/a2900.pdf
Or could it be done by just raising the R1 resistor to 1k ohm?
Or should i use another LED color for correct bias?

As a don't have a volume control in my Crack, i'm ok with the higher gain.

Edit: I can imagine it being a no-go as the current would be to low for the LED to light up/function for getting it within save function. And lower bias would trow off the 6080 function.
« Last Edit: April 16, 2019, 11:04:14 pm by Tom-s »

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #1937 on: April 17, 2019, 04:30:56 am »
That tube has way, way too much amplification factor.  The extra 15dB of gain that you will get from using that tube will be very unwelcome.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Tom-s

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Re: Tube Rolling w/Crack
« Reply #1938 on: April 17, 2019, 07:11:41 am »
Aside from the fact that it would be a problem in a Crack with volume control.
I'm ok with the extra gain. I just want to try this tube, and run it in optimal conditions for Crack (if possible).
Could i just make the R1 resistor in speedball a bit higher to get it to work?

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #1939 on: April 17, 2019, 09:09:38 am »
No, I mean when you move the volume control 5 degrees or so, you'll likely be near full output on the Crack.  In order to run that particular tube with the red LEDs on the socket providing bias, you'll run so little current that you'll be off in the weeds in terms of where the linear operating areas are. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man