KT88 application notes

[Turret]

I'm looking for old KT88 application notes (not datasheet), or any unusual KT88 powered PA schematic. Something similar to 200W Hiwatt PA's (4xKT88, 4 output coupling caps, quart 220k bias split supply resistors) but... with four trimmers. Help dudes, I'm getting nuts!

[gingertube]

This is a typical example but other ways to skin the cat.

Cheers,
Ian

[jazbo8]

Not really an application note, but it has the individual bias for the output tubes, there's nothing special about that, is there?

[VacuumVoodoo]

Straight from the horse's mouth: https://tubeamparchive.com/download/file.php?id=24508

[Turret]

Not really an application note, but it has the individual bias for the output tubes, there's nothing special about that, is there?

May be nothing special, but I never came across of it ever before

The thing is I'm working on Marshall 'The Pig' schematic and layout, I'm 90% there, just that funky off the main/preamp board PI caps and trimmers given me a headache

Anyway, thanks man, I think this s what I was looking for, now I'm back to work

[surfsup]

Ian, any gutshots of that VDV-3070 amp? I'd love to see the grounding scheme...

[jazbo8]

The thing is I'm working on Marshall 'The Pig' schematic and layout, I'm 90% there, just that funky off the main/preamp board PI caps and trimmers given me a headache

Anyway, thanks man, I think this s what I was looking for, now I'm back to work

Cool, glad it is all sorted out, BTW what's "The Pig"?

[Turret]

The Pig is the rarest Marshall amp out there. AFAIK only 10 units ever produced. One of the Marshall's oddities. It had 3 knobs - Master Vol, and 2 band valve powered active EQ, quart KT88, Partridge transformers. Preampwise nothing alike to other Bassman based preamps. There is no schematic for one, not much sharp enough pictures to drawn conclusions. At least there was no before, as I said, I was 90% complete, thanks to you I'm 95% right now

[Reeltarded]

There is a reason that amp only went for a short run. I am not sure about production numbers but I think it's more like 25 amps. There are a couple around at friend's places with no transformers and I have actually been on-site with two other working amps, but not unmodified.

That eq blows up an amp that is already going to blow up! Boom!

Be interested in the later model and I'll help you all you like, but damn that thing!! lol

[Turret]

There is a reason that amp only went for a short run. I am not sure about production numbers but I think it's more like 25 amps. There are a couple around at friend's places with no transformers and I have actually been on-site with two other working amps, but not unmodified.

That eq blows up an amp that is already going to blow up! Boom!

Be interested in the later model and I'll help you all you like, but damn that thing!! lol

Ha, that would be awesome if you could help. I'm not going to build one myself, I just do it in sake of rarity and lack of common knowledge about technical aspects. Plus - unusual topology gives me that kind of push to do it.

If mods could rename this tread to 'Marshall 'The Pig' or something I can add all schematic and layout I already have

Do you think you could take the chassis dimension and more pictures?

[Reeltarded]

I don't have the early modes. I have the Genex designed later models.

I believe that is the same chassis size. The boxes are square from the side. As deep as it is tall. A swimming pool, a public swimming pool. An aquatic arena sized swimming pool.

I am sure you must have seen this by now?

http://www.drtube.com/library/schematic ... emas#Major

[Bob S]

One of those was responsible for the ringing in my ears.
The start of it anyway.
Think sonic attack.
Loud.

[jazbo8]

I am sure you must have seen this by now?

http://www.drtube.com/library/schematic ... emas#Major

Cool site, never seen it until now, thanks. The generic schematic shows the OPT with ultralinear connections for the screen, is that also used on the Pig? Also don't see the active EQ...

[Turret]

There is no active EQ on DrTube website, as there is no 'The Pig' schematic out there

Here's early preview, no component values, no PS nor bias supply yet, I'm working on it

[Roe]

There is no active EQ on DrTube website, as there is no 'The Pig' schematic out there

Here's early preview, no component values, no PS nor bias supply yet, I'm working on it

thanks for posting. a previous schem and pics were posted on the metroboard. and there's new info in the new doyle book as well, claiming that the design wasn't worth much really