Matchless filtering and rectifiers.

[azatplayer]

Got an odd thing here. I lent a buddy my Express to try out, see if it was his thing. In return he dropped his Matchless HC85 to me for a few weeks. Have a look at it and retube etc. They ony made 25 of these super heavy beasts.
4 x EL34 in cathode bias... yum!
I really like this amp, killer tone.
So i starts mapping it out, its pretty usual fare for matchless, same stuff they do everywhere, gets to the dropping string and took the tape off the filters to see what we had there. Shitty IC caps. They have 4 x 100uf/450V caps with 220k balancers across each pair. So thats fair, 50uf plate 50 uf screen.
They run a pair of 5AU4 rectifiers as well, each are rated at 40uf first filter, so we have 80uf max, sounds good right?
What looks odd is they have them all in a row, postive ends all facing the same way, BUT all the grounds ARE grounded!
There is a bridge wire between each pair for series wiring, and theres no connection at the end of one cap on each pair other than the bridge wire, there are 220k balance resistors. But the first and second cap in the series setup are both grounded! Therefor its all make believe and theyre running 100uf plates AND screens, with rectifiers rated for 80uf total.
Im gonna email them a pic and see what they say. I cant believe they would make that kind of blunder, nor run the recs past their rating. Its a matchless for goodness sake.
All that aside, the thing sounds killer
Will try and get some pics uploaded later.

[Gaz]

Any series resistance with the rectifiers? Did you measure the DC resistance of the PT? All may be well. Then again, I don't know how ratings change when two rectifier are used in parallel. Maybe someone can chime in.

BTW, you should definitely draw up a schem of that amp.

[azatplayer]

I am going thru it, its pretty much a phoenix with 2 tubes, but FAR less heat. Its running 390R/100uf each cathode vs 270R/250uf of the phoenix or clubman or chief.
Just realised its git dissimilar recs in it. A 5U4GB plus the 5AU4. But from spec looks like the 5AU4 is a little heftier version of the 5U4GB and has the same first filter max of 40uf.
I emailed them with pics. See what they say!

[azatplayer]

OK, its entirely DC30 preamp, verbatim. Has all styrene caps apart from the tone control .02's, theyre M150's, and the .047 output coupling caps that are also M150's.
Change to the dropping string;, 47K to PI, 6K8 to V1, 5K6 to EF86, 6K8 to V2
Filters the same in the preamp as the DC30.
Cathodes are 390R/100uf, screens have 900R each. Theres a 1K/50watt resistor from the choke return to the screen node. And the power tubes have 47K grid stops on the outer pair and 33K on the inner. The inner pair switches out with half power.
Also 330K grid bias resistors.
Basically a Phoenix with a cooler running power section, and twice the tubes.
Was surprised by all the styrene caps, and makes me glad too, cos ive been stock piling them for just such a build. Interesting to see the poly smear used here and there.

[diagrammatiks]

matchless has always been styrene for as many positions as possible.

[azatplayer]

I was a little surprised as ive been in a couple of their amps and they were totally polyester thruout, even pf values.
Seen a few pics of early amps tho, and they look mostly styrene in the early years.

[diagrammatiks]

which ones are polyester through?

Granted I haven't seen pictures of every matchless but all the ones I've seen have been styrene.

[azatplayer]

I've been inside a Phoenix and a lightning, both newer amps made in the last few years. No styrene at all.
I bought a bunch of trw styrene caps in big coupling values a while back. Was glad to see they use them too. Tho the bigger caps were Mallory branded.

[diagrammatiks]

hmm I haven't seen any recent matchless insides.

I wonder what they are doing for their matchless branded caps now.

Their old supplier was bought out

[azatplayer]

Check em out here matey. They do gutshots of all their amps. http://www.proguitar.eu/ProGuitar.eu/Matchless.html