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In Reply to: Anyone else using a pentode as a driver tube? posted by Bas Horneman on February 19, 2007 at 04:51:31:
Bas,Funny I was doing this last week. I needed a larger gain than I could get for a new 20-25W amp. I have three gain/driver stages I am going to try.
I basically setup a EL84 with regulated screen with two 22.1K 12W mills in parallel for the plate. Running the whole thing at like 25ma. So far so good.
The second idea was parallel 12AX7A, running them pretty hard. I think this is a waste of time but still best to try all avenues.
The third is this cascaded 6922 I did years ago for the Cornet integrated 300B amplifier. It's pretty hefty and has about the same gain as the EL84.
I also thought about using the Telefunken EF804. They are suppose to be real nice sounding and much higher drive than say an EF86.
Follow Ups:
Hi Gordon, not the 804 nor the 86 as these are not intended to deliver large grid currents . c3m or c3g seem to be a better choice , even trioded ! cheers
Hi.Check out ACE 8 watt EL-34 SE monoblock, also available in
DIY kits (www.chimeralabs.com), using only a 12AX7 parallel to drive the EL-34. Response: 16Hz - 33KHz +/- 1dB (1W), & 23Hz - 33KHz +/- 1dB (8W).It earns rave appraisals from critics & end-users alike.
c-J
PS: someone posted down below about its "ugly sister" - ECC82/12AU7.
Are they really that "ugly"?Ask Andrea Ciuffoli (www.audiodesignguide.com). He posted his OTL+OCL project years back using one ECC82 parallel simple cathodyne phase splitter, to drive 2x6C33C-B twin power triodes. What can be worse to drive the current hungry power triodes run in parallel ???
.
To infinity and beyond!!!
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