Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: goldstache on August 20, 2014, 04:41:34 pm

Title: Build recommendations for this Power Transformer
Post by: goldstache on August 20, 2014, 04:41:34 pm

I've got a new in box NOS Chicago Transformer PT


Here are the specs:


350-0-350 120MA


5V 3A


6.3V CT  4.5A


I would like to make a brownface voiced amp and would really like to add reverb.  Trem isn't a necessity.


Anybody got ANY suggestions?  I am open to everyone's input.  Would like clean over mean, although a little in-between sounds cool too!


I kind of would like to end up with a brownface princeton with verb!


Thanks

Title: Re: Build recommendations for this Power Transformer
Post by: DummyLoad on August 20, 2014, 07:07:56 pm

dilemma: brownface amps didn't have reverb...


princeton reverb with P-P 7591 cathode biased.  with your PT, B+ should be around 450V with SS; w/ GZ34 about 10V less.


delete bias supply and tremelo ckts.



idle @ ~40mA/7591; load ~8-9K @ ~25W.  <-- likely a custom wind or one of the hammond one_size_fits_all...


that's the only thing i can think of other than a SE plan with a big bottle or possibly P-P 5881's into 6-7k load.



http://frank.pocnet.net/sheets/127/7/7591.pdf (http://frank.pocnet.net/sheets/127/7/7591.pdf)


--pete

Title: Re: Build recommendations for this Power Transformer
Post by: thermion on August 21, 2014, 03:14:51 pm

Insert reverb a' la 6g16 vibroverb?

Title: Re: Build recommendations for this Power Transformer
Post by: goldstache on August 23, 2014, 10:35:40 am

Thanks for the recommendations!  I have this amp that a guy built me back in the mid 2000's.  I would like to build something similar and add verb to it.
Can anyone distinguish the markings on the transformers that are on the amp?
I searched them on the net and found nothing.  Do they look familiar?????

Title: Re: Build recommendations for this Power Transformer
Post by: goldstache on August 23, 2014, 10:36:28 am

and here is the PT

Title: Re: Build recommendations for this Power Transformer
Post by: DummyLoad on August 23, 2014, 02:44:45 pm

they look like custom wound PT & OT by hyboer transformers. call heyboer and give them the part numbers and they should be able to provide the specs.

they were manufactured 2006, 43 week.



--pete

Title: Re: Build recommendations for this Power Transformer
Post by: eleventeen on August 23, 2014, 06:40:36 pm

Ooh, ooh, ooh, please let us know if indeed those are Heyboers, because I have a NOS "JTM-45" PT whose label looks exactly the same (except for the different numbers, obviously)

Title: Re: Build recommendations for this Power Transformer
Post by: Willabe on August 23, 2014, 07:13:02 pm

Quote from: eleventeen on August 23, 2014, 06:40:36 pm

Ooh, ooh, ooh, please let us know if indeed those are Heyboers, because I have a NOS "JTM-45" PT whose label looks exactly the same (except for the different numbers, obviously)

I don't understand.

If 1 of the #'s starts with 996 it's a Hyboer.


                  Brad    :think1:

Edit: Corrected spelling of Hyboer. Brad

Title: Re: Build recommendations for this Power Transformer
Post by: eleventeen on August 23, 2014, 07:33:16 pm

The obvious label similarity. I didn't know about the EIA/mfr number. Sorry.


(http://i172.photobucket.com/albums/w32/ttm4/tranny003_zps7e988fae.jpg)

Title: Re: Build recommendations for this Power Transformer
Post by: Willabe on August 23, 2014, 07:55:55 pm

Nothing to be sorry about.    :icon_biggrin:

I just wasn't sure what you wanted to know. I only knew 996 was Hyboer because of Pete's post.


            Brad     :icon_biggrin:

Title: Re: Build recommendations for this Power Transformer
Post by: goldstache on August 24, 2014, 09:12:23 am

I fired off an email and am awaiting a response!  Thanks! I will keep ya posted.

Title: Re: Build recommendations for this Power Transformer
Post by: goldstache on August 25, 2014, 08:30:16 am

They are indeed Heyboer.  And they sent the specs in their gracious reply.
I was surprised to see that the PT was 190v-0-190v @400ma!!!!!  Wow that's a lot of current for a two stage pre, LTPI, power section PP 30watter?!

Also no bias tap.   

I thought the secondaries were gonna be a lot higher.  I wasn't going to take measurements unless I didn't hear back from Heyboer. 

Thanks guys!

Title: Re: Build recommendations for this Power Transformer
Post by: DummyLoad on August 25, 2014, 09:49:51 am

Quote from: goldstache on August 25, 2014, 08:30:16 am

They are indeed Heyboer.  And they sent the specs in their gracious reply.
I was surprised to see that the PT was 190v-0-190v @400ma!!!!!  Wow that's a lot of current for a two stage pre, LTPI, power section PP 30watter?!

Also no bias tap.   

I thought the secondaries were gonna be a lot higher.  I wasn't going to take measurements unless I didn't hear back from Heyboer. 

Thanks guys!

what is the OT?


--pete

Title: Re: Build recommendations for this Power Transformer
Post by: goldstache on August 25, 2014, 11:10:35 am

As I suspected 3.3k primary

Title: Re: Build recommendations for this Power Transformer
Post by: goldstache on December 09, 2014, 07:27:28 pm

I want to make an ampeg SB-12 with the transformer mentioned in the first post
350-0-350 @120ma
5V @ 3A
6.3V @ 4.5A

But I think I'm trying to hard to use the wrong power transformer.
So........ I've decided to make a single ended KT 88 amp with reverb.
Tube rectified preferred. 
Does anyone have a shared schematic that could be a starting point?