Little fun with the Heathkit UA-1

[Brice]

Hi guys,

Quick post regarding the rebuild of a pair of Heathkit UA-1. I hope it will give you some ideas for restoring other vintage gear.

I received those little guys half dead like this but all Xformers tested good:


So I went for a full rebuild.

First I've got nice cans from hayseedhamfest.com with 125 - 125 - 50 @ 450V and 50 @ 50V Audio cap.
This allowed me to beef up the PS a bit, and I followed X3workshop's footstep for the implementation of a choke and the amp's wire dressing.

I stripped the chassis and sent them to M&P Refinishing in Jeannette PA for a chrome job.
The only modification on the chassis was the addition of a fuse holder as there was none in this amp.



They came back like this:



I also followed Dave's post (A Diamond in the Rough: Polishing Heath's AA-30) on the feedback adjustment.

For safety I added a 125 mA fuse in the CT of the HV winding to ground, as well as 2 SS UF4007 rectifiers before the tube rectifier, just in case.
The primary being now fused too, this amp is now much safer than before.

I had to hunt for those Heathkit plastic logos. I finally got 2. And I added the Daka Ware pointer knob.

Anyway, long story short, here is the result.

Inside:


Playing:





Looking good no ?

I hope you enjoy,
Brice.

 

[zackthedog]

Those are terrific. Nice job!

 

[Tinkerbelle]

Great work! Much improved aesthetics and design tweaks . Thanks for sharing your project.

 

[fredtroy]

You did a great job. They are surprisingly nice sounding amps, the feedback switch makes a big difference.

 

[Brice]

Thanks guys.

I removed the feedback switch and the preamp sockets. Less noise.
Yes they sound really nice. Blind test you would think it's a much more powerful amp than what it is.

It was a fun rebuild, although it's still quite some work.

 

[dcgillespie]

My my, Brice -- you've been a busy boy!

Very nice!!

Dave

 

[tcdriver]

I like it!

 

[Redcatcher199th]

Great job! How does it sound ?

 

[x3workshop]

These amps, when tweaked as stated, are very impressive from top to bottom. A great big shout out to @dcgillespie for sharing his knowledge when I rebuilt my first pair. @Brice these are real lookers too!

 

[Ezd]

Nice restoration.

 

[GuyNoir]

Beauteous!

 

[Brice]

Thanks guys.

Great job! How does it sound ?

As good as it looks

Very nice EL84 sound, which I like a lot. A lot of bass, perfect mids and highs. They sound like a "real big" amp.

The OTs are deceptively big: same size as the Acrosound 20-20. You would not think so but there have a lot of iron.

 

[Redcatcher199th]

I need to get a tube amp, It would be fun to build. I bought these tube's 15 year's ago, just didn't get around to finding a kit.

any suggestion's on a kit ? Thanks Brian

 

[Dandy]

I suggest that you start a new thread and list the tubes you have, as it’s hard to see just from the photo.

 

[Patrick_W]

Beautiful work Brice!

I bet they sound amazing, and almost as nice as a pair of Acrosound mono blocks.

Almost...

 

[x3workshop]

They give the acrosound 20-20 a run for its money. Seriously. They are very good.

 

[Brice]

They try anyway...

Thanks Patrick.