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Old 22nd February 2014, 03:12 PM
Dwjames Dwjames is offline
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Join Date: Feb 2014
Location: Birmingham
Posts: 14
Default Re: CCS Mod for a KEL84, anyone got details?

After reading around a fair bit, I don't think a simple LM317 based CCS will do what I want given how easily it can do horrible clipping, so I had a look at servo bias circuits as well as a few others, but I've yet to find anyone who's shown a specific example of it working with a parts list, with PCBs available or anything in kit form.
The best solution I've been able to find is from Tentlabs who do a Tube Bias Control module which is basically a very low noise power supply plus 4 x individual bias control circuits. Clever stuff and supposedly better than a servo based solution.

The only real downside is that it's not particularly cheap, but it's the kind of thing that can easily be moved to a different amp at a later date. I'm tempted to give it a go.
I emailed Guido to ask if he thought it would work well in a KEL84 and he said he thought it would do an excellent job.

He also mentioned that their Electronic Choke would work very well in this amp in place of the standard choke

I'm pretty tempted to put an order in...
Any thoughts?
Would this take an already v good amp up to another level?
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