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Old 15th November 2004, 01:22 PM   #1
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Default modify eagle el84 for guitar

ive got an oldish eagle PA amp, 50 watt, 4 input, 3mic and an aux. i was wondering what mods would be recomended to use this for a guitar amp? the inputs are transistor pre amped, then to a 6a08?? thats what i can read, then 4 el84. would it be better to take the pre amp setion out, and replace with specific guitar pre amp?

if so, which one?

cheers for the help, steve.. ..
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Old 15th November 2004, 01:56 PM   #2
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Do you want to make it all tube or not?
If yes go here .
Plenty of schems!!
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Old 15th November 2004, 02:00 PM   #3
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I don't know what happen to scheamaticheaven.
The link I post it above but you can go over here
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Old 15th November 2004, 02:21 PM   #4
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cheers bud, i wasnt thinking of going tube but ill take a look, the trouble is i dont know a lot about tubes, and they get expensive quickly, ill have to look and see what cost is like. thanks though bud, see you later, steve.. ..
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Old 15th November 2004, 08:23 PM   #5
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If it's easy to take the preamp section out,go with tubes.But you must know that tubes have high voltages.
If you don't have enough space see the low voltages you have and go with SS.Keep the output with EL84 and try a simple SS design.
Do a google on guitar preamp stages.I think you'll find a lot.Or go to SS forums.The guys over there will help you!
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Old 16th November 2004, 05:06 PM   #6
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cheers guys, i wouldnt mind doing either, tubes or s/s, how expensive is tubes going to get?? i know i could go silly money but cheepish, simple tube pre amp?

i got a few ideas from Pass forum, and a few from a book on simple electronic projects for guitars.

but now ppl have said tubes im interested, space isnt an issue as im re-boxing to a box the same size as the top of the speaker cab.

cheers for the help guys, steve.. ..
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Old 16th November 2004, 06:28 PM   #7
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Will the current power supply handle the extra tubes if you add them? One thought I had was to make a SS/tube preamp. Use a 4558 and a 12AX7. Like a hot box/Real McTube(I think these are SS/tube, You can find designs on the Net) type pedal used as a pre amp. It runs the 12AX7 at starved plate(At least some of these designs do) at around 9V. Just a thought.
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Old 17th November 2004, 10:58 PM   #8
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dont know if the power supply will power extra tubes, i cant see any markings apart from 130v 0.3a, 6.3v 3.5a, and 6.3v 0.7a

now i assume the 130v 0.3 powers the tubes

the 6.3v 3.5a goes to the tubes so is heater power

the 6.3v 0.7a goes through a rectifier to the s.s. pre amps, a simple pair of discrete transistors by the way of witch there are three, mic 1, mic2, and aux.

Aux works fine for line level inputt from a cd player, and mic is low impedeance (600ohm) microphone.

there are 4 el84 tubes and one 6a08? poss 6aq8, cant read too well, the printing isnt to great.

do you think the power supply would hold up with another tube for the pre amp? thanks for the help so far, see you later, steve.. ..
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