Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: billcreller on April 26, 2012, 09:44:08 pm

Title: the loctal amp
Post by: billcreller on April 26, 2012, 09:44:08 pm

I finally put the loctal type tube amp in a cabinet.  The cab is a copy of the 5E3 cab, sort of....
  (http://i561.photobucket.com/albums/ss52/steelybill/P1011040.jpg)

(http://i561.photobucket.com/albums/ss52/steelybill/P1011039.jpg)

(http://i561.photobucket.com/albums/ss52/steelybill/P1011013.jpg)

(http://i561.photobucket.com/albums/ss52/steelybill/P1011012.jpg)

It's based on a Valco design, with loctal tubes in place of the octals.   Just something different...and it sounds just like the octal version.

Title: Re: the loctal amp
Post by: Willabe on April 27, 2012, 09:47:02 am

Where's the pics?     :dontknow:

Title: Re: the loctal amp
Post by: billcreller on April 27, 2012, 11:39:46 am

I don't understand why the pics were lost.....???
(http://i561.photobucket.com/albums/ss52/steelybill/steel%20guitars%20and%20amps/P1011039.jpg)

here's another one.   maybe it will disappear too ?

Another..

(http://i561.photobucket.com/albums/ss52/steelybill/steel%20guitars%20and%20amps/P1011040.jpg)

(http://i561.photobucket.com/albums/ss52/steelybill/steel%20guitars%20and%20amps/P1011013.jpg)

  (http://i561.photobucket.com/albums/ss52/steelybill/steel%20guitars%20and%20amps/P1011012.jpg)

and the last one......look before they disappear !!

Title: Re: the loctal amp
Post by: Willabe on April 27, 2012, 12:55:33 pm

Very Nice Bill!     :icon_biggrin:

Title: Re: the loctal amp
Post by: kagliostro on April 27, 2012, 02:03:59 pm

Nice Bill  :thumbsup:

can you post some higher resolution photo ?

I would like to see the tube side  :wink:

Kagliostro

Title: Re: the loctal amp
Post by: DummyLoad on April 27, 2012, 02:54:16 pm

Very nice work! :-)

Title: Re: the loctal amp
Post by: LooseChange on April 27, 2012, 03:21:09 pm

Nice build.. Sure is neat in there.

Title: Re: the loctal amp
Post by: Willabe on April 27, 2012, 06:59:12 pm

I found it in a GE book, 7AJ7, Sharp-Cutoff RF Pentode, 300v max plate, 100v max screen, 1w max plate, 6.3/300mA heater.

Title: Re: the loctal amp
Post by: billcreller on April 27, 2012, 08:43:46 pm

I used the 7AJ7 in place of the octal 6SJ7.  Seems to work fine.  Specs aren't an exact cross-over, but PRR sez amps are only 20% accurate anyway for values ! :icon_biggrin:

And my camera has a mind of it's own, sometimes works good, and other times.......

Title: Re: the loctal amp
Post by: plexi50 on April 27, 2012, 10:09:54 pm

That looks great Bill. Especially a different tube compliment. I have yet to build another 6SN7 / 6SL7 amp. The one i built 2 years ago sounded really nice and different. Smooooth. How does it sound?

Title: Re: the loctal amp
Post by: billcreller on April 27, 2012, 10:48:16 pm

It sounds just like the octal version, and has a 12" Weber ceramic mag speaker like I used in the octal versions.  It's an old Valco/National 510B circuit with a few changes, like coupling and cathode cap sizes etc.
  The 7AJ7 is sort of hard to find on some tube sites, so I bought a couple of extras. The output tubes are 7C5s which are very close to a 6V6,  and the rectifier is a 5AZ4, which seems very close to a 5Y3.