Hughes & Kettner Cream Machine - output impedance?

[Johnny85]

I just bought a 1990's H&K Cream machine from eBay.  It's a little box containing a tube preamp, ~1 Watt tube power amp, dummy load, and cabinet-simulator.  You can take a line-out at line-level or instrument-level after the output transformer and feed it to pre-amp input, so you can get power-tube saturation sounds at low volumes. 

It also has a "speaker out" socket where you can plug in a speaker and thereby use the Cream Machine as a practice amp.  Since I read an old post by RG Keen saying that the Cream Machine output transformer was a special one-off design for this device and you can't get them anymore, I am concerned not to ruin it by putting the wrong speaker impedance in the "speaker out" of the H&K.

So if someone on here has some experience of this machine (like the mighty "Free Electron", didn't he take one apart for a project once?) and knows what the output impedance is, I'd be grateful if you could tell me.  Any information about the Cream Machine circuits, known problems, parts sources, is also greatly appreciated.

I can't wait for this thing to arrive!  I live in an apartment with a 40-Watt Mesa/Boogie Blue Angel combo, so I have been lacking power-tube saturation for some time!

[Johnny85]

Me again.  Free Electron responded to a PM I sent him.  For anyone in the future Googling to find the Hughes and Kettner Cream Machine output impedance, the output transformer was designed for an 8 ohm load.  Luckily enough this is the same as my Mesa Black Shadow, so I don't have to buy any more speakers 

Many thanks to Free Electron.  Check out his stuff if you haven't already!  He has pictures in the Pictures thread of some stunning work, and also a great site at http://www.hexeguitar.com/main.

[free electron]

I'm glad i could help.
This is a very nice small amp, although without the tone stack and enormous amount of gain was too limited for me. I think i've rebuilt it about four times, adding pre and post tone stacks, noise gate etc...
I have somewhere an unfinished article about the Scream Machine, the final version i'm using now.
If anyone is interested, here's a schematic
and a photo of the finished unit:


Output transformer data (measured on my unit):
Rpri = 848R
Rsec = 2R
Voltage ratio: 51.1
Impedance ratio: 21.2k : 8R

[Johan]

Output transformer data (measured on my unit):

Impedance ratio: 21.2k : 8R

that sounds mighty close to a fender reverb transformer...
I had a cream mashine once too, but in my quest to make it suit my taste, all parts ended up on different shelves..
the O.T in the C.M. is physicaly about twice the size of a Fender Champ transformer but only pushes about 1 Watt, so I wouldn't worry too much about it geting fried even if you plug into 4 Ohm
the cream mashine is a fun little unit that many people love. but in my opinion, single ended amps don't do hi gain very well. something ugly happens in the low end and they loose that solid feel on the lows (opinion, opinion, opinion  ) and a Tweed Champ is about as good as that consept gets...

Johan
ps. sorry if that came across a little discouraging..it's just one mans opinion thou..