Preamp

[cr_XD]

hi, i just bought an eleca eg-50t head, which when opened up seemed to be an american design sthepens or stevens, i can't remember. The point is that i was modding it for an effect loop. it appeared like the connections where hidden in the front panel but the guts where just prepared for it. eventually the effect loop it came with was parallel and i needed serial to go with my gt-8 (cracy reverbs and funny stuff) so i just took the output from the preamp into the gt-8 and the output of the gt-8 into the poweramp.

Anyways and sorry for the bla bla bla but i needed to freak out a bit

the point is that being a gear junkie and having the amp a couple of days at home made me wanna have a valve output stage at home and not a ss tiny amp, what is gonna make me buy a valve junior rip off called harley benton. now, i want to use it as a power amp. I´ll replace the preamp tube with a 12au7 for less gain.

For the shake of modularity, i tought that i could have myself a preamp (high gain) so i could use it at home and with the eleca, which lacks a bit of heavy metal sound sometimes. The point is that, having analyzed some schematics: can i just take the preamp schematic and clone it forgetting about the poweramp. I know i should keep al voltages and stuff the same.

What are you thoughts on this?? my idea was a slo100 preamp or alike.

thank you

[Motorbreath]

Got a GT-8 and a Carvin Legacy for live work. I don't use it with a tube amp because I think it colors the sound, and in a bad way imho (I used and tested every possible connection, direct to power, 4 cable method, it simply won't work for me). For studio work, I use the amps I build. If you are handy with electronics, a tube amp circuitry is very primitive by today's standards and you can easily build a pre or poweramp. ax84.com is a good place to find info and schematics tested by members. I have built two amps using their legacy schematics with little modifications for my personal needs and I am happy with both of them. Both of them Class A and low wattage, they are loud enough for the studio.

Take care.

[cr_XD]

okay, it was long time since i didn't surf that web.

The contents are much better now.

all the models of preamp, man, i like it. the point is, can i just put one in a pedal like the mctube??? it would be killer

and i use the preamp stage of my engl screamer in my effect loop as preamp, i do not use the boss' i just love the sound, but i suppose that with another amp could be different. with my electa i haven't played much yet, playing is always long with the boss, too many pots and params, i just love it.

any comments on the preamps isolations would be really wellcome.

thank you very much

[cr_XD]

sort of what is said here.

i guess i´ll just try building a preamp and just adding a pot at the end to have control over the output volume, exactly like in the real mctube, but i´m sure it has also to do with impedances, how is this??? i don't know much about the electronics theoretical backup though, i´ve always wanted to learn, but i´d rather pick the soldering iron with someone else's design, tooooo lazy

and c'mon, i know there is really knowleadgeable people out there, i did search the forum, promise, not found anything however, please help me

[curtisa]

My main rig is based around a clone of the third channel of the Soldano X88R preamp - sounds schweet! The X88R is a three channel preamp, but you can easily build each channel seperately. The dirty channel of the SLO100 is almost the same as the 3rd channel of the X88R too, so if you can find a schematic of either then you've got the same thing.

There is a schematic floating around the net for the X88R - just do a Google search.

[cr_XD]

how would you go to mod a valve junior so as to use it as a power amp??

do you think chaining to another valve in the pre stage would be enough or that i would have to completely bypass it??

what tubes do you suggest as a replacement?? 12at7?? 12au7??

i´ll be getting one at the end of the week and i would really like to mod it quickly so i can take it on holiday XD

[curtisa]

how would you go to mod a valve junior so as to use it as a power amp??

do you think chaining to another valve in the pre stage would be enough or that i would have to completely bypass it??

If you're already using another external preamp, you can bypass the preamp in the Junior. Adding more preamp stages in front of the Junior will just give it more gain.

what tubes do you suggest as a replacement?? 12at7?? 12au7??

What's your favourite book? What's your favourite food?

Whatever takes your fancy! - if you have some 12AT7 or 12AU7 tubes lying around try them out. They're pin-for-pin compatable, so you can just swap them straight in. The 12AT7 and 12AU7 are both medium-gain twin triodes; less gain than the 12AX7, so I'd expect the 12AT7/12AU7 to be cleaner in sound.