Epiphone EA-50T Pacemaker ‘64

[tomof63]

Hi all,
I’m new to this forum. I also belong to the Gibson amp forum on fb. I didn’t want to resurrect an old post on the ea-50t so I started this one to address my specific questions. I have done some updates and mods on my ‘69 Princeton no-verb. Recapped, 12” speaker mod, Torres perfect prince and adjustable bias mods. The Princeton is really easy to work on as the wiring and eyelet board is easy to follow. The epi by contrast is a rats nest. The past post by blueguitone was super helpful. I have changed c2 to a .022uf coupling cap. I have also jumpered the t-filter (Sprague 102c824) just after c2 to the volume pot outer lug. I have the correct schematic for the ea-5t. It has 2 6eu7 2 6aq5 and a 6x4 rectifier. I have 2 questions which I’ll try and post some photos for reference.

[tomof63]

I neglected to offer my thanks in advance.

1. So just curious if the jumper is correct?
2. Can anyone reply and circle or mark in some way c5?
3. If I up the value of c5 to 1-5uf per hot blue plate, what type of cap is recommended?

The last photo is the .001uf cap I replaced with an identical Sprague that I installed.
Thanks again for any information!

[shooter]

not sure about your jumpers, one's black, ones red and I can't see the other end.

as to C5, use anything in your junk drawer rated >10vdc and you should be good

[sluckey]

Jumper looks OK. What are you trying to achieve?

see pic...

[tomof63]

Thanks for the replies! I really appreciate the information!

Jumper looks OK. What are you trying to achieve?

see pic...

I am trying to complete the modifications that were suggested by HotBluePlates in a reply to blueguitone's post in 2010.

Just to clarify, the orange disc cap in parallel with the resistor?

[tomof63]

Here is HotBluePlates quote:
There are other issues in the non-trem EA-50 circuit that hold it back gain-wise. That's not so much the case with your amp. You could raise C5 (the 2nd stage bypass) to 1-5uF to bring back some fullness to your amp's sound. You can go as high as 25uF or more, but you don't need to do that to get a full sound and full gain.

He also suggested the jumper and replacing the .005uf c2 with a .022uf , which I have done.

Thanks again!

[sluckey]

Just to clarify, the orange disc cap in parallel with the resistor?

Isn't my pic perfectly clear?

[shooter]

fwiw;

doing them "all at once" could ask for problems, the reason I like 1 at a time, I can decide "how much change" for each change
The suggested changes are  all worth doing looking at the schematic.

[tomof63]

Thanks for the input! I appreciate it!

Just to clarify, the orange disc cap in parallel with the resistor?

Isn't my pic perfectly clear?

It is clear, I just over think things when I don't have to.

fwiw;

doing them "all at once" could ask for problems, the reason I like 1 at a time, I can decide "how much change" for each change
The suggested changes are  all worth doing looking at the schematic.

The jumper and the coupling cap change made a big difference. The idea of opening it up a bit more sounds appealing. I can always undo  the mods if necessary.

Parts ordered from Hoffman.

Thanks again for the help!
tomof63

[sluckey]

I should have mentioned that the 4.7µF electrolytic cap is polarized. The positive lead must connect to pin 4 of V1. And the negative lead must connect to ground.

[tomof63]

Thanks for the heads up. Looking forward to wrapping up the mods.

Thanks again for any and all info!

[shooter]

Want even more fun mods;
Once everything is up and working;

Swap out C6 for a .022uF
Change C12 from 20uF to 47uf
Try removing C13

[tomof63]

Toward what type of improvement?

[shooter]

what type of improvement

the 1st 2 should bump low end up and possibly tighten it.
the last one, it's just for fun, since most modern amps don't use it. 

[tomof63]

I’ll take a look at the schematic and see if I can find it.

[shooter]

https://el34world.com/charts/Schematics/files/Epiphone/Epiphone_Schematics.htm

[tomof63]

Update:

First, thanks for all of the advise and help. The mods (c2 changed to .022uf, jumpered T-filter, and c5 change to 4.7uf) are complete and the amp sounds vastly improved. It went from ice pick shrill with single coils, to a much fuller tone. The treble is still there but is manageable. I have a Boss eq pedal and/or can roll the tone back on my guitar if need be. The original its '64 10" speaker probably isn't doing the amp any favors in the treble department. With a humbucker equipped SG it really grinds when cranked. I'm going to modify the speaker connections (in a reversible way) so that I can try a Weber Mini Mass that I have, with the amp. I play the guitar mostly in the evenings so even though this amp is only 5 watts, to get it to over-drive without pedals requires it to be too loud. The amp has retained its touch sensitivity, especially at lower volumes. When pushed the touch sensitivity is tempered somewhat by the saturation and compression. Pretty happy with the results. I'm going to leave it as is for the moment, but I'll keep the additional mod suggestions from shooter in my back pocket for now.
Thanks again!
tomof63