Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TubeGeek on July 21, 2011, 09:23:24 pm
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Finally had some luck today...found a tv shop with a stash of tubes.
Here is what I was bought...
Is the e88cc a useful tube for guitar amps?
Same with the telefunken ef85?
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Nice! :wink:
Brad
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The E88CC and its functional equivalents - ECC88, 6922 and 6DJ8 certainly can be used for guitar amplifier service. Unfortunately the 6.3 volt heater means they are not interchangeable with members of the 12A*7 family, without rewiring the valve socket.
Valve hifi zealot$ love E88CC's. You may find a home for them there.
I found a stray box of valves in my shed a couple of years ago - I have no idea where it came from. :dontknow:
The contents are pictured below:
(http://i497.photobucket.com/albums/rr333/valvetone/magnesium/valves.jpg)
With 124 E88CC/6922 valves looking for homes, I began using them in several of my amp builds, as a gain recovery stage and cathodyne phase splitter. They work fine in that application.
(http://i497.photobucket.com/albums/rr333/valvetone/magnesium/backfinal.jpg)
That particular construction article is here: http://www.guitargear.net.au/discussion/index.php?topic=18245.0 (http://www.guitargear.net.au/discussion/index.php?topic=18245.0)
Sorry I can't offer any advice on the EF85 - I've never used one. :sad:
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Yeah I did look up the datasheet and found that they were indeed twin triodes. They do look useful and definitely built with quality in mind. The gold pins are nice touch.
I tested them in my hickok 600 transconductnce tester and they measured 10,000 mho's! Significantly higher than 12ax7's and similar in my tester.
I'm sure someday I'll find a use for them.
You sure have a nice collection. Oh and I am drooling over the nixie tubes you found! :occasion14: I'd love to score those and build a neat clock project someday.
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The 6DJ8/ECC88/E88CC is highly valued by hi-fi people. Your best use (especially for the gold-pinned E88CC's) is to sell them to the hi-fi folks.
You can use them in amp circuits, but they specially optimized for use in cascode circuits (or grounded-grid, which is usually described as "cathode-drive" on the data sheets).
You have one tube marked "ECC83/12AX7 Made in Germany" which has a plate structure like an american 12AT7. I have a few tubes like this as well. I can't remember offhand if they actually exhibited 12AT7 gain or not.