Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: balancedtriode on December 31, 2011, 03:48:59 AM

Title: The Possibility Of Crack Monoblocks?
Post by: balancedtriode on December 31, 2011, 03:48:59 AM

I was in the shower this morning, and I was thinking about trying to make Crack monoblocks
My Idea kinda went like this,
Wire the the Crack as mono, add a output transformer, put binding posts where the RCA jacks go and Put a RCA jack where the headphone jack goes and eliminate the volume control.
my question is
Is this even possible to do?

Title: Re: The Possibility Of Crack Monoblocks?
Post by: Doc B. on December 31, 2011, 06:17:17 AM

You would end up with a 600mW or so amp that has not that much gain gain due to the step down ratio of the output transformer. The S.E.X. kit on the other hand could be turned into a PP monoblock with a reasonable amount of output power and gain. I believe Xavier has tried this. 

Title: Re: The Possibility Of Crack Monoblocks?
Post by: Paul Joppa on December 31, 2011, 06:45:02 AM

You could convert it to push-pull and probably get some useful power. Here is a circuit I found by googling "6AS7 push-pull":

http://ja1cty.servehttp.com/6080/60802.html

You'd have to re-design the LTP first stage for triodes, and sub in a current source for the -160v supply, but the basic idea is sound. Might be hard to locate a 2KCT output transformer, in both senses of the word.  :^)

Given the poor DC balance of almost all 6AS7/6080 tubes, I would use the Speedball as cathode bias to equalize the currents in teh two halves, and cap-couple the cathodes to each other.

Title: Re: The Possibility Of Crack Monoblocks?
Post by: Doc B. on December 31, 2011, 06:57:04 AM

Oh yeah, wasn't thinking of changing the CF to a voltage amp. Not going to be easy fitting an OT on the chassis, that's for sure.