WD88VA schematic

[diceman]

I have Shian7 / Gromits old WD88VA and woudl like to start and tweak it/see what has already been done to it and hence wondered if anyone had a copy of the build manual or schematics.

I am not that experienced in but have modded a couple of tube pre-amps to date so will proceed with caution!

A few things I am looking in to if anyone has further comments:-
1) upgraded output transformers - Sowters?
2) Ascertain if KT120 can be accomodated and heater current increase is suitable for wd88va transformer.
3) Better PSU or uprated caps.

Obviously I first need to get the schematic and lift the lid to see what has already been done.

Many thanks for any assistance.

ATB JP

[pre65]

The filaments draw between 100ma - 300ma more per valve.

Quote "This is the most powerful audio power tube in production today. With a plate dissipation rating of 60W (compare that with the 35W of the 6550, the 42W of the KT88, and the 50W of the KT90), a pair of these KT120 tubes in push-pull configuration can deliver 150 watts or more of audio power. And when used in a vintage circuit designed for 6550 or KT88, the KT120 will deliver unbelievable amounts of clean headroom, low end rumble and dynamic punch all without overloading. The glass of this tube is a full 1/2" taller with the internal plate structure 3/8" longer than its nearest KT88 cousin. The internal control grid cooling fins are twice as large as the KT88 adding to the amazing performance of this tube. This particular tube draws between 100mA (.1A) and 300mA (.3A) more filament current than a standard KT88, so check with your amp manufacturer to insure you have the additional filament headroom to power these tubes"

[bob orbell]

Hi JP,I think Colin Hepburn will help you with build instructions, if not I have it on CD, let Colin see this first. I think someone else asked the question about KT120 valves and the answer was dont, too much heater current. as for upgrading PSU, this is the best move you could make, did it to mine a few months back using Evox Rifa capasitors and bypased with smaller ones, fast recovery diodes for both HT & LT also pi filter for LT, fantastic improvement, recomend it, but the big ER capacitors are very expensive. As for Sowter transformers, can't comment, mine with all it's mods and stock transformers is very very good. Someware on here is the CD for the upgrade PSU and a photo of mine. BOB

[diceman]

Thanks for the comments.
It sounds like KT120 will be a major ball-ache to work and require transformer swaps and possible PSU mods. I did search and found a couple of threads that seemed to have petered out.

Is Colin Hepburn the guy that is now in control of World Audio?

I will search harder for more info on PSU mods (I am not sure if they were part of the XL upgrade or what mine has so will pull the lid off tonight.

Found this so far:-
http://www.world-designs.co.uk/forum...ight=evox+rifa

[bob orbell]

JP, the PSU upgrade is part of the XL kit, Colin is a moderator for the forum, no, he is asuper moderator, sorry Colin, Matthew Snell is the top man now, thankfully. The picture is mine in XL form. BOB

[diceman]

Many thanks, the pic gives me something to compare mine with :-)

[colin.hepburn]

Originally Posted by bob orbell

JP, the PSU upgrade is part of the XL kit, Colin is a moderator for the forum, no, he is Super moderator, sorry Colin, Matthew Snell is the top man now, thankfully. The picture is mine in XL form. BOB

Hi Bob/All
Yep I am just one of the three Super moderators for the WD forum Sorry Diceman I cant help you with the WD88VA manual I don’t have this one BOB its back to you for this one

[vinylspinner]

Hi guys,

I have the build instructions etc if anyone needs them, please just pm me.


Nigel