Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: AnalogDok on April 10, 2021, 09:57:32 pm

Title: 5E3 Sluckyamps with AO-29 iron
Post by: AnalogDok on April 10, 2021, 09:57:32 pm

I sure hope I'm not making a big mistake here.
I downloaded the Slucky 5E3 Tweed amp schematic and layout files to go with a AO29 power and OT tranny.

I bought the AO-29 no-FC speaker version as matched up with the photo comparison. Tranny is marked  AO-24110-1, 549-6443.
The tranny is supposed to be a 320-0-320. I've seen various 5E3 transformers from different vendors.
Hammond 330-0-330 or 355-0-355
Mojotone 384-0-384
MM 290-0-290 or 380-0-380

So I figured the AO29 would be fine. Then I'm reading about very high voltages for the 6V6 5E3 from it and not a good match.

Am I headed in the wrong direction or can I use the iron from the AO29 in the Slucky 5E3 build?

I love the 1624T build I completed from Slucky with the AO35 iron.

Any insights on how to make this work or do I just bite the bullet and buy different iron?

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: sluckey on April 10, 2021, 10:05:00 pm

Quote from: AnalogDok on April 10, 2021, 09:57:32 pm

I bought the AO-29 no-FC speaker version as matched up with the photo comparison. Tranny is marked  AO-24110-1, 549-6443.
The tranny is supposed to be a 320-0-320.

I'd use it.

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: AnalogDok on April 10, 2021, 10:25:06 pm

Thanks for the fast reply.
Any issues with the OT tranny?

I mean other than 1/2 the shell missing as a laydown unit and no mounting feet...LOL
I ordered shells cheap with mount feet to convert to a stand up unit...

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: sluckey on April 11, 2021, 06:32:36 am

OT is fine, better than what came in the original. I'd like to see a pic of the OT with your new end bells.

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: AnalogDok on April 29, 2021, 05:00:14 pm

It took a minute for the bells to arrive from China.

(https://i.postimg.cc/HxFx5s2r/5-E3-Iron2.jpg)
(https://i.postimg.cc/SsnRJzW0/5-E3-Iron1.jpg)

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: AnalogDok on July 16, 2021, 11:59:28 pm

Here are the pics of the completed build.

(https://i.postimg.cc/Y9K2JGvs/5E3.jpg)
(https://i.postimg.cc/hG7Pybtm/Guts.jpg)

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: AnalogDok on July 20, 2021, 01:58:56 am

I did have to pull the 250Ω 10 watt cathode bias resister and bump it to 330Ω.
It was pushing 45mA @ 326v measured at the tube.
Now it's at 39mA @ 324V. Approxinately 85%...GTG

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: AmberB on July 20, 2021, 02:11:58 am

Very nice build!
I didn't know you could get end bells for the transformers...

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: sluckey on July 20, 2021, 06:55:26 am

Quote from: AnalogDok on July 20, 2021, 01:58:56 am

I did have to pull the 250Ω 10 watt cathode bias resister and bump it to 330Ω.
It was pushing 45mA @ 326v measured at the tube.
Now it's at 39mA @ 324V. Approxinately 85%...GTG

Did you subtract the cathode voltage from the plate voltage to calculate power?

Title: Re: 5E3 Sluckyamps with AO-29 iron
Post by: AnalogDok on July 20, 2021, 10:06:58 am

I used a Bias probe and used the calculator on the Robinette site.