Solid state rectifier question

Double-Bubble! Place for discussing the 36W version...

Moderators: CurtissRobin, colossal, zaphod_phil, Daviedawg, Graydon

Post Reply
User avatar
lespaulblues
Newbie
Newbie
Posts: 45
Joined: Thu 11/13/08 2:00 am
Location: Unknown

Solid state rectifier question

Post by lespaulblues »

I'm just putting the 36watt together using the phat ass rectifier layout.
Is the load resistor the 220k going from the first side of the + on the
can cap to ground?
What determines the resistor value?
What sort of rectified voltage should i be getting for the b+.
Thanks
0 x

rock_mumbles
Senior Amp Tech
Senior Amp Tech
Posts: 826
Joined: Mon 04/21/08 2:00 am
Location: Podunk, Idaho
Contact:

Re: Solid state rectifier question

Post by rock_mumbles »

lespaulblues wrote:
...
Is the load resistor the 220k going from the first side of the + on the
can cap to ground?
...
That sounds like the power supply bleed resistor ... how about a link to the schematic you are referring to ...
0 x

Pressed_Rat
Occasional poster
Occasional poster
Posts: 218
Joined: Thu 05/12/05 2:00 am
Location: Upstate, NY

Post by Pressed_Rat »

I guess you are referring to Scott Rubel's Phat Ass 16 schematic? Yes, that is a bleeder resistor, used to bleed down the power supply filter caps when the amp is shut off. I think 1/2 watt is sufficient; typical practice is to use 1/2 watt unless otherwise indicated. Won't hurt anything to leave it out, but you'd better be careful poking around the chassis. Actually it's best to be careful anyway.
0 x

User avatar
guitar-rocker
Occasional poster
Occasional poster
Posts: 286
Joined: Tue 06/15/10 2:00 am

Re: Solid state rectifier question

Post by guitar-rocker »

lespaulblues wrote:I'm just putting the 36watt together using the phat ass rectifier layout.
Is the load resistor the 220k going from the first side of the + on the
can cap to ground?
What determines the resistor value?
What sort of rectified voltage should i be getting for the b+.
Thanks
As mentioned, the 220K is the bleeder resistor. Were you actually inquiring about a sag resistor, because on the Phat Ass, there was not one used.
0 x

User avatar
lespaulblues
Newbie
Newbie
Posts: 45
Joined: Thu 11/13/08 2:00 am
Location: Unknown

Post by lespaulblues »

No i wasn't going to use a sag resistor.
Any idea what dc voltage i should get with the 36watt mains transformer
with 240v mains?
I haven't done solid state before,that's why i'm asking.
Thanks.
0 x

User avatar
scottva59
Newbie
Newbie
Posts: 85
Joined: Tue 07/22/08 2:00 am
Location: Northern VA
Contact:

Post by scottva59 »

I dug up and old schem. of a 36w version I did with the GDS xfmr set with voltages noted.

http://farm8.staticflickr.com/7200/7050 ... 9239_b.jpg

Here I did use a sag cuz I was trying to get the B+ down a little. Can't trust my memory but I think with out the sag I was getting just over 360v using 120 mains. Nothing stopping you from experimenting with or without a sag and trying different values, season to taste. Hope this helps. The as built version of this amp had a great bark!

Scott
0 x

sub
Frequent poster
Frequent poster
Posts: 811
Joined: Thu 03/23/06 2:00 am
Location: Europe

Post by sub »

I think a 2W resistor would be better here.
If B+ is 360V then: (360x360)/220000=0,59W.
0 x

User avatar
scottva59
Newbie
Newbie
Posts: 85
Joined: Tue 07/22/08 2:00 am
Location: Northern VA
Contact:

Post by scottva59 »

Yep, 2W for bleeder.
0 x

User avatar
zaphod_phil
Builder, Admin
Builder, Admin
Posts: 14990
Joined: Wed 03/19/03 2:00 am
Location: YYZ

Post by zaphod_phil »

I dug up and old schem. of a 36w version I did with the GDS xfmr set with voltages noted.
http://farm8.staticflickr.com/7200/7050 ... 9239_b.jpg
Those were actually 6V6s in the power stage, and not EL84s, right?
0 x
Nature abhors a clean tube amp

User avatar
scottva59
Newbie
Newbie
Posts: 85
Joined: Tue 07/22/08 2:00 am
Location: Northern VA
Contact:

Post by scottva59 »

That version was a quad of EL84s - Rocket inspired (cloned) output power stage. I've never tried a quad of 6V6s.
0 x

Post Reply