Showing posts with label Brook 12A. Show all posts
Showing posts with label Brook 12A. Show all posts

Thursday, March 15, 2018

Brook 12A Clones Completed

I finally finished my Brook 12A clone build. The looks are early radio amplifier inspired and the build is pretty close to the original Brook. The only changes are much larger chassis, more modern grounding scheme, shielded input and feedback cables.
Changes? I think I am going to finish the bottom boards to match the top and call it done.
Now I need a few pairs of 2A3's or at least two more of the same brand. I've got a pair of sovtek and EH. Ultimately I'd like a quad of JJ's.

There were a few bumps along the way. It was not behaving well at all on first light but Chris helped me chase the gremlins away.

This is of the new happy amp.

One more check up and they go to the big speakers. 


Lessons learned:
Use real hardwood not plywood.
Don't wrap metal chassis in wood.
Don't trust Sams Photofact.
Wear pants while soldering.
Wear pants!

Wednesday, September 14, 2016

Brook 12A Imposter

Brook 12A clone or imposter or nisemono. Just received the iron from the good people at Heyboer. The Brook wasn't built with fancy parts yet still had a great reputation. This is most of the parts for the Brook imposter except for chassis, tube sockets, and meters.
I had some of the parts, some were given and some were found on the ebay. I've been looking forward to this project for a long time. It will give me something to do while Chris and I work on the..... whatever the hell we decide to call the massive amp. 

 

Monday, August 8, 2016

Brook 12A Datasheet

I ordered the original photo fact off of ebay as I had never seen all the data. Since I am building it this year I should have it. My version will be larger due to parts selection. The first build will be pretty much stock. I am curious about what tweaks would you guys make to the 12a? Not wanting to get too far from original design.


 Original schematic with error of C3 being reversed. Any other errors?

Thursday, July 14, 2016

Brook Electronics 10C3 and 12A3 Advert

Very cool Brook ad. Posting this in anticipation of the clones.

I would love to have a copy of the free technical bulletin and distortion analysis..

Friday, December 4, 2009

BROOK Electronics 12A one of PWK's favorites


I think I've finally found the Brook 12A modification specifically for Klipschorns. Brook and PWK worked on this in the early days of Klipsch. This document comes straight from the Paul W Klipsch archivist Mr.Hunter. At first I thought I had the wrong document because it lists the 6B4G instead of the 2A3 but they are close enough it turns out. The 2A3 and 6B4G are used interchangeably in the 10C and 12A schematics. The Brook 12A 2A3 PP amp was reportedly one of PWK's favorite amplifiers. He talks about it in his interview with vacuum tube valley at the age of 94. The last time I was in Hope, AR I got a good pic of PWK's actual Brook 12A23KI and preamp. It is still in his office. Here is the pic.
 EDIT
* SORRY guys I seem to have screwed up on this one. This is not the PWK mod but a different schematic from the archives. Can anyone identify what critter this is from?  *

This schematic is supposed to be of just the modifications of the Brook 12A to the 12A3KI. If anyone can shed light on this and what it actually does please please comment on this post. Here it is

Here is a schematic I've found on the electroweb.

Here are some great Brook preamp and 12A pics and a stereo pair. My ears crave this setup.


A couple of links.
An interesting post on Brook click here.
A TubeCad article on the Brook by John Broskie click here.