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What to do with two pre-tubes and four EL84s

5/2/2003 11:58 AM
Chris ( CMW amps )
What to do with two pre-tubes and four EL84s
Hi all  
Just did purchase an old Eko SuperDuke amp . Right now the amp does have two 12AX7s and four EL84s , cathode biased and about 350 Volts on the plates . Two inputs and 3 controls .  
I'm looking for some suggestions for a nice project using this amp . Gotto check out if it's possible to add another 12AX7 but maybe some fellow Ampagers do have some great ideas about this new project .  
I can also rebuild it to a PaisleyRoyal 30 amp with an EF86 pre-amp but I'm also looking for other options .  
tia & have a nice weekend !  
5/2/2003 12:34 PM

On our 18 watt group, they have some offshoots of the 18. You could do a lite channel with no trem..They also have an EF86 style preamp.Only difference would be running 4xEL84 instead of 2.  
Lots of options out there..  
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5/2/2003 12:58 PM
Chris ( CMW amps )
thanks / EF86 suggestions
Thanks Richie , cool 18 Watt forum !  
Re-uilding an amp with four EL84s i.o. two ain't no porblem . Did try a couple of pre-amps in an EL84 pp-amp like the '59 VOX AC15 , Matchless Spitfire and a Fender Blackface . Right now I do really like the '60 AC15/EF86 pre with a few tweaks ; fat , punchy and very dynamic .  
Guess I'm gonna build a VOX AC30/4 ( like the early ones with an EF86 pre ) .  
I'm also looking for some EF86s suggestions , during building & tweaking I did use some UOS Philips ones and my new Ruby ones are coming in in a few weeks .  
Just did try the Eko : tone-stack sucks ( can cause icepicky highs ) but there's a nice chunky tone in that OT .  
5/2/2003 3:07 PM

The first thing that comes to mind is a Vibrochamp.  
I like the idea of substituting 4 parallel EL84's for the 6V6 power tube. Too bad you have a PP OPT.  
Still I would probably not make up my mind completely about that chassis until after I had tried a cathode biased quad of EL84 with a Vibrochamp preamp.  
5/2/2003 3:38 PM
Chris ( CMW amps )

Mike ,  
wicked idea !!! Really have to try it with a hefty SE-OT . This (pp)OT must be pretty good and due to some constructing/groundloop weirdness I've to rebuild this amp anyway .  
If I do wanna use the Vibrochamp tremolo-circuit I've to add another 12AX7 .  
have a nice & rockin' weekend !  
5/2/2003 5:00 PM

Didn't you already make an EF86/15w? Why not make "big brother" or what about a 5E3(incl. cathodyne PI) with a 30w power section.  
5/2/2003 5:15 PM
Chris ( CMW amps )

Hi Philip  
Yep , did make a 15 Watt with EF86 pre and a 30 Watt version would be way cool too . Did ask for suggestions 'cause they're always welcome !  
The "British 5E3" idea looks cool too and with just two inputs it does match the stock frontpanel-layout from this amp .  
have a nice & rockin' weekend !  
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