Gibson to Fender

[andy81563]

Hello everyone,

I am a total newbie to amp building but am going to build a tube amp.  I have a Gibson Saturn GA-45RVT amp that is a mess.  From what I have read, It seems that it is not worth trying to put this Gibson amp back in working order so I am going to gut it and put in Fender AB763 architecture.  One of many questions I have is what kind of AB763 system should I use?  The cabinet is in decent condition.  The two 10" (8 ohm) speakers are fine.  The reverb pack is junk.  I want to use effects pedals so what I mainly want from this amp is something that will produce good, clean sound.
Thanks for your help.

[shooter]

If you're looking for magic, probably not gonna happen, but if you fix what's wrong on the Gibson, you'll know what you have for something else

otherwise it's just a cluster

https://el34world.com/charts/Schematics/files/Gibson/Gibson_Schematics.htm

[echuta13]

I think it would be a shame to turn this into a Fender circuit.  That's also a rather deep dive for someone who is not well versed in building amps. Just my $.02  but I would recommend doing research on the amp and see what you can do to fix/improve what is already there. 

[vampwizzard]

open er up and share a few pictures and lets see whats in there.

IMO it would be a hell of a lot easier to document and replace all the electrolytics in this and get it working or sell it as is to fund a 763 amp build. Restore vs make a new amp. http://www.0rigami.com/gg/amps1.html#GA-45RVT_Saturn_White-Panel

[j_bruce]

I would fix it, just sayin".

[shooter]

https://el34world.com/charts/Schematics/files/Gibson/Gibson_ga45rvt.pdf


If you're using effects, scrap the trem n verb, that just leaves the "upper 1/3rd" +
re-wire V1 & 4 to just V1, new Ecaps, NO tube bias and voltage check, you're 3 days from a tube screamer, wahha, stuff

[Latole]

Totaly newbie in tube amp , it is not the good way to start

[labb]

If you want to build the AB763 then go here   http://sluckeyamps.com/misc/AB763_Deluxe_Lite.pdf    look at building the Deluxe AB763 Lite that does not have Trem or Reverb...Straight forward...Say thanks to Steve.

[P Batty]

Uncle Doug has dealt with the tone problems of these Gibson amps:

He goes through it in detail, it should help you decide if you are up to it.

[shooter]

good for the tweak stage, It needs to make guitar sounds 1st

this might give you an Idea what bare minimum probably looks like.

[bmccowan]

Totally newbie in tube amp , it is not the good way to start

This is wise advice. That era Gibson amps had some unusual features - so called tone sucking circuits, and transformers for phase inverters. And that model is complex. As is what you want to build.
I suggest you set it aside, and build a simpler amp. Since you want clean - a blackface Champ or Princeton would do. And you'd have lots of info to draw from, including verified schematics and layouts, and lots of help on this board.
And then you could decide on the path for the Gibson.
Whatever you decide - read all the safety stuff and get comfortable with it.

[P Batty]

I rebuilt a similar Epiphone amp and basically gutted it and built a single channel AB763 Bandmaster with no effects. The transformers are usually very good in these Gibson amps but everything else needs to be changed, including the heater wires. More questions than answers in taking on this kind of project.

I bought a GA 45RVT new in 1967, it was OK, but nothing special.

[andy81563]

Thanks for the comments.  My brother, who has built several tube amps from scratch, basically told me the same thing; build something simple.  This Gibson would have been worth fixing if it was not such a train wreck.  Wires were running everywhere, it had no organization at all.
I know it's quite amusing for all you experienced ones out there to read posts from greenhorns like me.  You have to start somewhere and as long as I don't get electrocuted, there is no harm in tinkering.

[shooter]

Wires were running everywhere, it had no organization at all.

organization is in the eye or the beholder, the amp obviously worked when sold.

If your goal is nothing more than a working amp then this is probably not worth it.  If your goal is to understand amps, fix and build them, then you have a great amp in hand.  You just need to do the homework for understanding, get comfortable with the "tools of the trade" and you're there.  your call, your goals

[andy81563]

I have decided to build an 5e3 tweed deluxe.  I have a PT and OT from an amp build my brother started a while back but never finished.  There are no markings on them and he doesn't remember the details.  Is there any way, short of using an elaborate test setup, to tell what the rating is of these transformers?  Or is it better to just obtain new ones?

[sluckey]

Ask your brother what he intended to build. May be some clues there. Post some pics.

[shooter]

Or is it better to just obtain new ones?

using an elaborate test setup

only you can decide;
what's your objective, to build a kit, or to understand how and why it works

[dpm309]

My first build was a 5E3 tweed deluxe. I had some basic knowledge in electronics but by building this from scratch, I really understand how a tube amp circuit works. I took my time building this amp, double and tripled checked everything, and it fired up the first time. Have built several tube amps since but this is still one of my favorite and most versatile amps.

[andy81563]

My plans are to build a stock tweed deluxe.  I want to have a nice tube amp to play through and to learn how they perform and what makes them sound so good.  Here are the transformers...

[shooter]

the OT clearly shows 5K-SE, so single ended, NOT push-pull
you'll have to "plug in" the PT and measure, or maybe surf-up the part #