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| Music Electronics General discussion about music electronics |
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| | #1 |
| Senior Member Join Date: Jul 2008 Location: Auckland
Posts: 128
| Holden Wasp 200XL rebuild
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! |
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| | #2 |
| Supporting Member Join Date: Feb 2007 Location: Wellington NZ
Posts: 2,662
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That's quite a snazzy restoration there. Very Nice
__________________ Building a better world (one tube amp at a time) |
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| | #3 |
| Member Join Date: Apr 2008 Location: Australia
Posts: 74
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Wow, how heavy is that beast? Those transformers are just huge!
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| | #4 |
| Senior Member Join Date: Jul 2008 Location: Auckland
Posts: 128
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| | #5 |
| Senior Member Join Date: Apr 2007 Location: sydney australia
Posts: 777
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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
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| | #6 |
| Senior Member Join Date: Apr 2007 Location: sydney australia
Posts: 777
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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...
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| | #7 |
| Senior Member Join Date: Jul 2008 Location: Auckland
Posts: 128
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| | #8 |
| Senior Member Join Date: Apr 2007 Location: sydney australia
Posts: 777
| 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? Last edited by black_labb; 03-26-2009 at 11:46 PM. |
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| | #9 | |
| Senior Member Join Date: Jul 2008 Location: Auckland
Posts: 128
| Quote:
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| | #10 |
| Senior Member Join Date: Apr 2007 Location: sydney australia
Posts: 777
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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. |
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| | #11 |
| Senior Member Join Date: Apr 2007 Location: sydney australia
Posts: 777
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