Comparing two 50W homebrews - choke differences

JimmyR · Post by **JimmyR** » Wed Jan 17, 2007 6:54 am

I built a 50W with bits and pieces I had laying around late last year after seeing the Marstran site with all the useful historical info they have there. It worked out so well that I decided to build another in George's new steel chassis, based on a '68 circuit.

The only real differences between the two amps - apart from tubes and chassis - is that the new one has a Marstran JMP style O/T and 3 Henry choke where the earlier one I used a Heyboer plexi-style O/T and 10 Henry choke. Both have all Sozo caps, incl a .68 on V2 cathode, split cathodes on V1, and the dual 33uF filter to the middle of the board. Both are pretty accurate circuit-wise to the '68 on the Marstran site that has the schematic attached. I left off the bright cap on the vol though.

It is really interesting to see what the differences are. They're actually very similar in tone. Both sound great with HBs when the channels are linked and both vols are around 4-5. Beautiful bite and sustain. Strats need slightly more on the vols to break up the same but can sound absolutely enormous through these amps!

I'm not sure how much of the perceived differences can be attributed to the O/Ts. They do sound quite similar. But they feel different to play. The 3 Henry choke amp seems to feel less punchy but somehow more tactile - maybe it seems to compress a little more or something? Hard to explain. The 10 Henry choke is bolder but not quite as sweet. I would have trouble picking a favourite as I like aspects of both! Notes just fly out of the 10 Henry version but they sing a bit more from the 3 Henry.

The 10 Henry version is already with a friend for sale so I have only the newer one now. Not hard to put up with! These amps are so versatile - I'm getting seriously warm and beautiful cleans and with a twist of the vol knob getting great bite and grind. And there is a serious level of dirt here too! Way more than I'll use; in fact anything over 5 is metal territory.

Funny how Marshall got so much right so long ago.

neikeel · Post by **neikeel** » Wed Jan 17, 2007 7:54 am

Could not agree more.