Holden Wasp 200XL rebuild

[unparalleled]

My rebuild is now featured on:
http://ozvalveamps.elands.com/holden...00XL%20Rebuild
Although the new PCB is mentioned, the photo is not correct.
The correct image will be posted in due course.
The ANZ site has a lot of useful info which is applicable to other amplifiers.
Check out The Lamington, an amplifier built on an oven baking tray from off the shelf
currently available parts!

[tubeswell]

That's quite a snazzy restoration there. Very Nice

[andrew_k]

Wow, how heavy is that beast? Those transformers are just huge!

[unparalleled]

Wow, how heavy is that beast? Those transformers are just huge!

HEAVY! would guess 30Kg.
The carry handle on the end is was a popular add on.
I also own a NZ made 1970s Gunn 200 w slave amp which is similar in bulk.

[black_labb]

glad you put this up, you've motivated me to draw up a schematic to my VBL, which i've been meaning to do for a while

[black_labb]

this is taking longer than i expected. partially because my multimeter has decided to go funny (instead of reading infinite, the maximum resistance is 358ohms). i would be troubleshooting it, but its a bit hard without a multimeter...

[unparalleled]

glad you put this up, you've motivated me to draw up a schematic to my VBL, which i've been meaning to do for a while

The drawings are on ANZ amps already!

[black_labb]

The drawings are on ANZ amps already!

there's only a drawing of the slave and a 100w one with a more marshall style preamp. the preamp on the vbl is quite different.

edit: just saw that the holden/wasps have grid no.3 linked to grid no. 1. does anyone have any knowledge about this? does grid 3 do anything with the signal, or is it just another way to connect grid 3 to a certain voltage (a -ve as opposed to connected to ground). could this be a way of saving the tubes from frying regularly with the 775v B+ and possibly class ab2?

[unparalleled]

there's only a drawing of the slave and a 100w one with a more marshall style preamp. the preamp on the vbl is quite different.

edit: just saw that the holden/wasps have grid no.3 linked to grid no. 1. does anyone have any knowledge about this? does grid 3 do anything with the signal, or is it just another way to connect grid 3 to a certain voltage (a -ve as opposed to connected to ground). could this be a way of saving the tubes from frying regularly with the 775v B+ and possibly class ab2?

THIS CIRCUIT? Obviously the PA section is different.

[black_labb]

the vbl is quite different from that. the 2 channels are kept separate until they reach the PI. they both have 2 gain stages (12ax7's with 100k plate resistors, 820r for the cathode with a 150uf cap across it connected to the cathodes of both triodes in a tube) between the gain stages are the tone stacks and volume controls. CH1 has a fender style TS with a 6.5k resistor instead of a mid control, and different values. Ch2 has a marshall style TS, but has some quite different values from norm (notably a 100k resistor instead of the usual 33k, and a 250k bass pot). modelling it up in the tone stack calculator gives a fair bit less bass than usual for a marshall TS.
just looked at the output, and it is the same as the 200w slave, but someone has added an extra resistor across the original -ve feedback resistor (original was 82k, extra parallel one is 47k, should be 30k resistance). wether that was from the factory or not i'm not sure.

the vbl runs the plates at 775V (still using the same 350v filter caps, should probably replace those with 400v rated caps and reform the elna's for another project). the xl i have runs the plates at 700v. not sure wether the xl is the same circuit as the schematic you posted, will have a look sometime.

[black_labb]

THIS CIRCUIT? Obviously the PA section is different.

i've seen that one, wanted to figure out the preamp for the VBL. partially to find out what amps i've been listening to before making my next amp.