can someone help me add brighness to this amp? w/Schematic

[sidehatch]

http://www.schematicheaven.com/gibsonamps/ga19rvt.pdf

Its a gibson falcon ga19rvt

It has a single tone control. I love the tone of the amp but when I have the tone all the way up its still too dull unless ina recording situation where I can add more post eq.

I put a .001 cap on the volume pot earlier today and it fixed that problem but the reverb now sounds horrible. Its very dull and unusable so its coming off.

Anyone know something simple I can try? Im not a tech but can solder and know how to not get killed by the amp. Other than that it really has to be spelled out for me.

I appreciate any help!

Shane

[selloutrr]

maybe you should try soldering a 47Pf up to a 1000Pf cap across the volume wiper? like the old Fender bassman amps.

[Jana]

you might try removing that .002 cap that is across the OT primary.

try removing that .003 cap, C7 i think it is, the one by the two 220K resistors

[jjman]

you might try removing that .002 cap that is across the OT primary.

try removing that .003 cap, C7 i think it is, the one by the two 220K resistors

Sounds good. I think that 500pf and those 2-220ks and the .003 cap are a mid-scoop? You may want to bypass all of that "nonsense" as a test.

[dave g]

Get rid of that stupid .002 across the 6V6 plates!!!! I guarantee that's a huge part of your problem.

I would personally leave the 500p/220k/.0033/220k network in the preamp in place. It's there as a sort of simulated tonestack that gets rid of lower midrange mud.

[sidehatch]

Cool, Im going to try to get rid of the .002.

I play a gig tonight inside a resuraunt and used my dumblized red plate carr slant 6 but the gig really called for the gibson because its just me and and a bass player.

My prs is much brighter than the guitar Im using now but the prs is off getting refretted now so Im using a Hamer with Manlius humbuckers. Its really good sounding-perhaps better even than my 91 prs I've played for 17 years but its darker and didn't fit well with that amp. Maybe with an EQ pedal it would be ok.


Can anyone point out the .002 in laymans terms? Im not a schematic reader although I can look at the layout and see if I come across it.

Thank you guys for all the help you've given me!
'
Shane

[Jana]

I don't know what type it is but it will be going from pin 3 of one 6v6 to pin 3 of the other 6v6. According to the schematic, there is only the leads from the output transformer and that cap that connect to pin 3 of each tube.

If you can't find it, take some pictures, we love pictures.

[sidehatch]

I will do some pics tomorrow for sure.

the only cap I see going to and from each 6v6 is a silver cap that says germay and 25uf. other than that I dont see any caps that connect the plates of both 6v6s

Is this the cap in question? Mine might be different than the amp in the schematic.

[roberto]

C5-C7-R9-R10 is a mid scoop to simulate tonestack. I think you can solve part of the problem by using 120pF as C5, or lowering C12 to something about the half of its value.
The first thing is to find and remove that 2n 1kV cap across T2.

[Structo]

How about that bypass cap on V1?
Is that really 20 mf?

[sidehatch]

falcon pics.

Are we talking about disconnecting the silver cap that is going from the plates of the 6v6's in pic 1? I removed that volume cap I put in yesterday.

I dont want to lose any bass. I'd just like to add about 20% more high end. I have the single tone control all the way up and I just can get it to cut with certain guitars even with the new speaker.

The amp sounds gorgeous by itself for what I play but add anyone else and it simply doesn't cut.

Idealy, I wish the tone control would sound like it does on 10 when its on 5 and that way I would have some room to eq for different guitars.

Thanks!

Shane

[Jana]

That silver cap is the cathode bypass cap for the 6v6's, (I think). It's hard to tell from the picture but is the right side of it, with the +++, connected to that point with the red/yellow wire, the black wire, the white wire, and the negative end of the big blue 20uf caps? That solder joint looks really iffy too. Is that ground? If so, that silver cap is in backwards. Where does the other end of the silver cap connect, is it pin 1 of the 6v6? which are hooked together with a wire? It also looks like that silver cap lead is coming really close to making contact with the terminal with the brown wires (heater wires?).

[Jana]

I still think you should try disconnecting that .0033 cap, C7 in the schematic. with that disconnected you would have 440k (2 *220k in series) bypassed with a 500pf cap, this would give a treble peaking filter.

[sidehatch]

I'll take a better photo of that area.

Can you point out the c7 cap?

I really need to get some books and learn how to read a schematic because I have no clue what c7 is except c,e,g and b flat!!!

[Jana]

I can't determine where it is from the pictures.