Just checked out a Bad Cat Hot Cat 15...

[Steve A.]

This amp was traded in by Steve Miller's manager to get one of those limited edition GC-only EC "Blackies", and I told a friend about it, who took it home with him ($2k must have been burning a hole in his pocket!)

I was really impressed how it was much more than the old Matchless designs- there are two input jacks going to 2 different preamps- 4 master controls: bass, treble, volume and I think brilliance. For the low gain channel there is a single volume control, while the high gain channel has pre-gain, post-gain and a treble-cut control (Darn- why didn't *I* think of that... LOL) It uses a tube rectifier, and has 6 9-pin tubes (with full covers on 4 of them and partial covers on 2 of them). When cranked up it sure sounds like more than 15 watts (a tweed deluxe is around 15 watts- right?)

In any case, I'm posting here just to check to see if anyone has any pix or schematics on the amp (I'm sure that there are a few tricks in there that I'd like to borrow). So what was the site that has all of the amp pix? I think I have it bookmarked... [Nope- I can't seem to find it! ]

$2K is a bit rich for my blood so I spent $107 on an Epi Valve Junior Head... gonna do my Les Paul Jr rewire on that with the bridged-T filter. (They seemed to have fixed the noise issue that the combo had.)

Steve Ahola

P.S. I blew the dust off my old D-clone and took it for a spin... I *FINALLY* hooked up a foot switch, at least for 2 of the 3 relays. LOL

[cocobolo]

In any case, I'm posting here just to check to see if anyone has any pix or schematics on the amp (I'm sure that there are a few tricks in there that I'd like to borrow). So what was the site that has all of the amp pix? I think I have it bookmarked... [Nope- I can't seem to find it! ]

Did you mean acplink.com? It used to have a bunch of matchless and badcat chassis pics but seems to have gone by the wayside recently. Schematic Heaven has some Hotcat 30 schematics though I'm not sure if that'll help ya. I have some pics of a Hotcat 30R chassis I could send to you if you are interested.

Take care,
Craig

[slajeune]

Hi,

if you are looking for acplink.com, it has moved to www.p2p-amps.com

Cheers,
Stephane.

[Steve A.]

Hi,

if you are looking for acplink.com, it has moved to www.p2p-amps.com

Cheers,
Stephane.

Hmmm... I just get a 404 error message when I try that link. Can you double-check it?

Thanks!

Steve Ahola

P.S. Some kind soul did email me a schem for the Hot Cat 30, which is basically the same except that it uses 2 EL34's instead of 3 EL84's. I wonder how the HC30 would work with 6V6's or 6L6's...? Maybe not agressive enough?

In any case, here's a run-down on the design: the clean channel goes through a single gain stage and then through a volume control directly to one of the inputs on the LTP PI (you will set the Brilliance control- same as the old AC/DC-30 Cut control to get the sound you want from the clean channel, and then adjust the rest of the controls for the OD channel). Nice and simple... no BS on the clean channel at all! LOL

As for the Gain channel, well there's a bunch of stuff in there- 5 gain stages (well, actually 4 plus a cathode follower). You might say that there is an extra gain stage before the DC-coupled pair going into the 2 knob tone stack... or not!

Input -> V1a -> GAIN -> V2b ->Edge->V2a->Level->V3b/V3a (DC-coupled pair)->Bass, Treble and Master-> phase inverter

Lots of gain stages like a Mesa Boogie, but one big difference is that it does not route the signal through a bunch of RC filters (when RC filters are used, it is often to shunt some of the signal to ground). All-in-all an interesting design, and in its own way almost as revolutionary as the SLO 100, only this time its a high gain amp for roots rock players as well as hard rockers (heavy metal heads need not apply! LOL)

I had thought that the drawing had a mistake in it because it showed the cathode of V1a connected directly to ground, but it was pointed out to me that Fender and Gibson had done that with their amps in the early 50's, so I guess it was designed that way.

[slajeune]

That's odd, I just re-tried p2p-amps and it works fine on my end. Can you try it again?

Cheers,
Stephane.

[Daver]

I got the same error Steve did when I tried it yesterday. Today it works fine. Go figure. Thanks for the link. I certainly missed that website.
Dave

[macula56]

hey Steve,
what is the purpose of tying the cathode directly to ground with no resistor?

[drewl]

I fixed one a couple months ago, shoulda' drew it out.
He bought a second one, so I'm sure one of them will be back.

[Chris / CMW amps]

hey Steve,
what is the purpose of tying the cathode directly to ground with no resistor?

That's called gridleakbias and was used in lots of early 50s amps. Pretty sensitive, some guys do really like that for harp.

The input goes throug a cap and then to the grid, most of the time a high value grid-to-ground-resistor is used (4M7 - 10M).

[macula56]

ok. i have two versions of the hot cat. one is standard 68K and 1 meg into the grid with a 1.5K cathode resistor bypassed with a 25 mf cap. the other is the grid leak bias set up. what would be the differences in sound? is one better than the other? i have several amps with the first set up but have never tried the grid leak bias. thanks. jmac

[Steve A.]

ok. i have two versions of the hot cat. one is standard 68K and 1 meg into the grid with a 1.5K cathode resistor bypassed with a 25 mf cap. the other is the grid leak bias set up. what would be the differences in sound? is one better than the other? i have several amps with the first set up but have never tried the grid leak bias. thanks. jmac

With the print I saw the OD channel has the "grid lock" thingee while the clean channel has a more typical input stage. "Grid leak" you say? Thanks but I went at home...

Steve Ahola

[Boogie92801]

Classic Cat

I just bought a CLassic Cat...

Seems like a mil spec version of a tweed deluxe.