Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on February 27, 2012, 01:58:52 pm

Title: Budda SD45
Post by: Leevi on February 27, 2012, 01:58:52 pm

I would like to hear some technical info about Budda Superdrive 45.
Even better if there is a schematic available. Is the circuit based on JTM45 but it is
using KT66 instead of EL34?
/Leevi

Title: Re: Budda SD45
Post by: The_Gaz on February 27, 2012, 07:34:41 pm

Shazam!

Title: Re: Budda SD45
Post by: Willabe on February 27, 2012, 07:52:13 pm

I think the 10R across (to ground) the 2@50uF caps at B+ node A and the 10R across (to ground) the 47uF cap at B+ node B are typos/wrong.

They would bleed off way to much B+ voltage and current.

Also the 1K B+ droping R between the plate (A) node and screen (B) node says 50w. 5w would be plenty.  
                  


                       Brad      :icon_biggrin:

Title: Re: Budda SD45
Post by: Leevi on February 28, 2012, 12:55:59 am

Thanks for your replies and schematic guys!
Is the only difference between SD45 and SD80 the number of power tubes (2 vs 4)?
/Leevi

Title: Re: Budda SD45
Post by: The_Gaz on February 28, 2012, 01:50:12 am

Quote from: Leevi on February 28, 2012, 12:55:59 am

Thanks for your replies and schematic guys!
Is the only difference between SD45 and SD80 the number of power tubes (2 vs 4)?
/Leevi

I assumed so. Either way, the SD80 has some very interesting tricks going on.

And yeah, there's surely some errors (this is not an official schem, of course), but you can get a gist of the amp.

Title: Re: Budda SD45
Post by: FYL on February 28, 2012, 12:24:55 pm

Quote

Shazam!

Mazahs!

Is this the first amp with a grounded phase in the PI ? Too many errors and typos in the schemo...

 :think1:

Title: Re: Budda SD45
Post by: Willabe on February 28, 2012, 12:53:55 pm

I thought there was something funny about the PI.

I thought maybe it was a para-phase drawn differently than the usual.



                    Brad   

Title: Re: Budda SD45
Post by: sluckey on February 28, 2012, 01:03:40 pm

Quote

Is this the first amp with a grounded phase in the PI ?

Please explain. I don't see what you're seeing. Looks workable to me.

Title: Re: Budda SD45
Post by: The_Gaz on February 28, 2012, 09:05:52 pm

I dunno, I guess the typos are problematic if you're trying to do a paint by numbers clone or something, but for someone who can recognize the errors, it's just interesting to see the overall typology (pun) of the amp. I think the simplicity of the channel switching, PI,  and cathode bias, and dual stage gain pot were particularly interesting - more than just the boring 'ol Marshall mods we're used to seeing.

Title: Re: Budda SD45
Post by: Willabe on February 28, 2012, 09:13:48 pm

Everybody makes mistakes/typos on schemos, even the guys who do it for a living. I know I do.


                    Brad       :icon_biggrin: 

Title: Re: Budda SD45
Post by: FYL on February 29, 2012, 09:17:33 am

Quote

Please explain. I don't see what you're seeing. Looks workable to me.

My bad. Typed too fast w/o considering the 270K load resistor between PI and bottom half of the PP...