Mildly Modded Mesa 5:25

[a2dconverter]

Here's what I did to my out of warranty Express 5:25

Installed JJ Tubes all around
Installed a bias adjust pot and meter test points on the rear panel
Installed a perforated aluminum shield to protect the EL-84's from cables/ footswitch storage in the rear of the amp
Installed a break-out box for the footswitch cable and IEC power cord
Added Fender 14" tilt-back legs

I tweaked the bias with the JJ tubes.. Everyone is happy :wink:
The other mods are convenience/ protection.

Let me know if you have any questions!

seeya

Joe

 

[gezza]

Hello a2dconverter,

Great mods buy the way.

Can I ask what is the amp fix bias set to?
I was just wondering if they run cold, medium or hot.

Boogie did a great job for the price, but I wish I had all those mods, but I will have to wait 11 more months before I finish the warranty.

Did you do the mods yourself or have someone do it for you?
Is there anyway of getting the 4 modes to be footswitcable? Cause that's a big waste right there.

Thanks for sharing,

Gezza.

 

[lerxst88]

sweet mods. its not original but its a players amp and thats what i like to see

 

[fredm]

Very nice. They should come from the factory like that.

Thanks for the info.

 

[a2dconverter]

Hello a2dconverter,

Great mods buy the way.

Can I ask what is the amp fix bias set to?
I was just wondering if they run cold, medium or hot.

Boogie did a great job for the price, but I wish I had all those mods, but I will have to wait 11 more months before I finish the warranty.

Did you do the mods yourself or have someone do it for you?
Is there anyway of getting the 4 modes to be footswitcable? Cause that's a big waste right there.

Thanks for sharing,

Gezza.

Hey Gezza, Thanks for the kind comments...

I do all of the electronics work on my tube amps.

For the stock Bias, I didn't measure that before I swapped tubes and started modding the bias circuit. Presently the I am set up at about 21 mA of Cathode current (that's about 8 Watt dissipation at rest with Plate voltage of 420 VDC)....I consider that relatively hot......sorry for my rambling technical gobbledegook 8)

The origianl reason that I did the variable bias mod is because I wanted to run JJ EL84 tubes and I wanted to make sure that the bias was set correctly (i.e. to my liking)

I like your idea of footswitch control of Clean to Crunch and Blues to Burn...may be able to parallel the frontpanel mode switches with relays...lemme look into it!

seeya

Joe

 

[rwil]

I like your idea of footswitch control of Clean to Crunch and Blues to Burn...may be able to parallel the frontpanel mode switches with relays...lemme look into it!

That will be great!
Very nice mod by the way!

 

[Wolfboy1]

I love the mods!
I have a brand new (2 months) 5:25 1x12 and my 2 main issues you fixed. The aluminum shield and the breakout box. Great mods that I will have to wait on. I'm very concerned about storing stuff in the amp pouch with the tubes the way they are in harm's way. So 2 questions:
1) Where do you get the perforated aluminum.
2) Can you give a little detail on how you did the breakout box for the cord and footswitch?
Thank you for sharing your ideas :idea:

 

[Don]

I love the mods!
I have a brand new (2 months) 5:25 1x12 and my 2 main issues you fixed. The aluminum shield and the breakout box. Great mods that I will have to wait on.

The footswitch cable doesn't stay plugged into the amp on the 5:25 like it does on a 5:50?

 

[a2dconverter]

On the 5:25, and I expect this is true on the 5:50 as well, the footswitch cable and power cord are anchored to the cabinet with a clip and a screw, but, both can be unplugged from the chassis. The power cord is a standard IEC connector and the Footswich connector is a 5-Pin Din connector.

I'll take some detailed pics of my breakout box and those chassis connectors, etc...

seeya

joe

 

[Mullenski]

Buddy -- if you figure out how to footswitch clean/crunch and blues/burn you've got a best friend for life and I'll nominate you for a Nobel Prize!

 

[a2dconverter]

Due to Popular Demand, (and I have a lot of extra time on my hands)...

here's a bunch of detailed pix of the Break-out box (the box is a Hammond 1590B Aluminum) and

the tube-shield (the shield is made and bent out of a thin piece of aluminum with evenly spaced and drilled 1/2" holes)

***PS I'm still looking at the possibility of switching the 4 modes remotely***

seeya

joe

 

[Don]

On the 5:25, and I expect this is true on the 5:50 as well, the footswitch cable and power cord are anchored to the cabinet with a clip and a screw, but, both can be unplugged from the chassis. The power cord is a standard IEC connector and the Footswich connector is a 5-Pin Din connector.

Yes. The 5:50 combo is the same, however, because it's a bigger amp, there's plenty of room to store the cords and the pedal.

 

[Wolfboy1]

A2dconverter THANKS!
Those are some great photos, I am saving them to my HD for when my warranty runs out but I WILL follow your fine exampe :wink: :idea:

 

[Tom M]

Nice clean work man, I am new to this amp but sure love modding. I too would love to see a footswitch that can toggle between all modes.

 

[gezza]

Hello a2dconverter,

Can you supply some pic's of the Bias Mod??

Also how hard would it be to mod??

I would like to Bias my own tubes.

I have no Idea just what life my tubes have, as I bought my amp as Floor stock.

Just buying any old tube and sticking it in, may or may not sound right.

Thanks,

Gezza.

 

[giorikas81]

Good job.

I would like to ask about something else: Have you taken a look at the amps cicuit topology? Not asking about gut shots but as far as the gain channel goes how exactly does the signal evolves?

input----Gain stage 1----eq controls------next gain stages-----contour filter.graphic eq-----loop--------power amp?

or input-----gain stages(all of them)--------eq controls-----contour-----loop-----power amp?

Also in the f-series v2 was the first tube that the signal hit so bear that in mind.

 

[soundchaser59]

Just looked at all your photos of the mod...... you do really nice work!

The breakout box is my favorite part. Boggle my mind why Mesa made that footswitch cable so hard to insert. That box looks exactly like the box EHX used to make the Soul Preacher compressor pedal.

I'm gonna order me some of those tilt back legs.