Ceriatone Plexi 50 Build (First Build)

[sdn25]

The 50 watt 68' Plexi, my Dream Amp!

Hey guys, this is my first ever amp build I've done, learnt a LOT along the way. It is officially completed as of today as I have received the head cabinet and finally eliminated all the issues that came up with it and caused heartache for the past 2 weeks , resulted in a blown OT and a blown set of power tubes but hey, we all learn somehow right?
Gotta hand it to the guys over at the workbench forum they helped me tremendously.

There were some changes I made to the circuit as well but they were all personal preference:
- 0.0022uf Bright channel coupling cap
- 47k NFB off the 4 ohm tap,
Also ended up with a OT upgrade to a heyboer 8025A-H as suggested by @william vogel since I had blown my original OT.

Do let me know if you guys have any cool suggestions as well !

Took me all in all about a month to finally have it completed and It sounds absolutely AMAZING. Here are some pictures for you guys to enjoy .I hope its of decent quality.

 

[Marcomel79]

Looks real nice, congratulations! Im sure you meant 0.022uF coupling caps. Play it loud!

 

[Pete Farrington]

A 2n2F coupling cap there will roll off a bit of low end.
Whereas 22nF extends down into the deep bass.

 

[pietro.castelli]

Congratulation! It looks really neat! I’ve also recently started my first amp build but I have chosen the “all access” version of the plexi 50w kit.

You can see my build progress here:

First amp build (Ceriatone Plexi All Access 51)

Hello Folks, This is my first post here. I decided to register to share with you my first amp build: A Ceriatone Plexi All Access 51 Kit that I purchased on reverb for a good price. I know this is not exactly a beginner kit, but I have some electronic engineering background, have some basic...

www.marshallforum.com

 

[sdn25]

Looks real nice, congratulations! Im sure you meant 0.022uF coupling caps. Play it loud!

Thank you man ! I indeed am able to play it loud as I use a load box.

Btw I mean 0.0022, the stock cap was a 0.022, I wanted that extra bite.

 

[sdn25]

Congratulation! It looks really neat! I’ve also recently started my first amp build but I have chosen the “all access” version of the plexi 50w kit.

You can see my build progress here:

First amp build (Ceriatone Plexi All Access 51)

Hello Folks, This is my first post here. I decided to register to share with you my first amp build: A Ceriatone Plexi All Access 51 Kit that I purchased on reverb for a good price. I know this is not exactly a beginner kit, but I have some electronic engineering background, have some basic...

www.marshallforum.com

Thank you! I tried my best in terms of cleanliness but could be better.

Your build is looking really clean so far dude, hoping it goes all well for you.

 

[BenTobith]

Thank you man ! I indeed am able to play it loud as I use a load box.

Btw I mean 0.0022, the stock cap was a 0.022, I wanted that extra bite.

That's a good choice, in my experience. I believe the 1987 circuit used a 2.2nF in the High Treble channel signal path by default, I'm wondering why that wasn't the case with the kit? Or maybe some earlier models used double 22nFs on the channels?

 

[marco_giampa23]

How did you blow a set of tubes and your OT? Asking so I hopefully dont make the same mistake in the future

 

[sdn25]

How did you blow a set of tubes and your OT? Asking so I hopefully dont make the same mistake in the future

When measuring the bias current using the bias test points at the back of the amp, I set my meter to read mA rather than mV. The meter set to read current gave me a skewed reading with which I set it to 33mA, in practice that was about 70 is mA which then caused overcurrent in the OT, shorted the primary windings, and blew a set of tubes as they were red plating.

just make sure that when you have current sensing resistors installed to help you easily set bias to not use the current setting on your DMM but rather voltage.