JM 100 watt build with higher resistance choke

[Guy77]

I finished up a JM 100 build today. I built another 100 watter earlier in the year and was not happy with the sound ( I mentioned it on another post and I turned it back into a 50 watter), it sounded a bit sterile compared to my original 50 watt build. On this JM 100 watt amp I used a choke that has a resistance of 400 ohms . The other 100 watter had a choke that had a resistance of only 100 ohms.

This 100 watt JM amp sounds sounds so much better with the larger choke! I was surprised at how much more rounder and lusher this amp sounds with a 400 ohm choke!
That's a Hammond 100 watt Twin Reverb Power transformer in the pic below. It weighs close to 12lbs! I was worried about it being noisy with the transformer standing up on end but it was dead quiet!


Cheers

Guy

[xtian]

I’m happy if you’re happy

[Guy77]

Thanks xtian, this amp really put a smile on my face tonight!

Cheers

Guy

[Roe]

I've built two 45/100s with different chokes (3h, 110ohm vs 20h 690 ohm). the big 20h choke drops the screen voltages and gives tighter bass. it works very well at higher voltages. The breakup of the amps sound different. The 3h amp has a fat, middy tone that is compressed, whereas the 20h amp sounds clearer and thinner when it is cranked. It cuts through the mix a little better.

[Guy77]

Hi Roe, yes I also noticing the tighter base with the choke that has more resistance and higher Henry value. When using an overdrive pedal everything holds together nicely and stays tight.
I am liking this sound better than the stock Fender Twin Reverb choke that I used before. I also added an adjustable negative feedback knob. The knob goes from the stock 12k value all the way down to 2k and I really enjoy how this changes the sound from thinner sounding to fatter sounding ( tweed style) by lowering the value closer to 2k.

Cheers

Guy

[Roe]

more screen resistance can sound good with kt66s and el84s. But I prefer lower resistance with el34s/plexis. Haven't experimented with 6l6s