Bluesbreaker built

[Thomas P.]

Today I've finished a Marshall Bluesbreaker.
I added a 10k-pot instead of the 6k8 in series with the clipping diodes and I divided the last 10nF cap into two 4n7 in series and added a switch to short one of them - it makes the tone stack more usefull.

The 10k-pot works good even if it's not such a big effect. It seems that he 'rounds' the corners a bit.

So far I'm useing a TL072 which gives a great sound. I also tried a NJM4558 which wasn't too bad but the TL072 gave a more bell-like tone.
Another idea was to use two opamps in parallel (which was mentioned in a thread not long ago). First I tried a LM833N which sounded a bit dull IMO so I put a LF353N (no reason for useing this type) on top and the sound really improved. But overall it sounded too compressed to me.
I tried two TL072's but that wasn't that good.

[brett]

I divided the last 10nF cap into two 4n7 in series and added a switch to short one of them

Do you mean 2 4n7 in *parallel*?  If they're in series, you've got 2n3.

Thanks for the report.  I've got a BB circuit on PnP, ready to go.  Sounds like and interesting effect.

[Thomas P.]

After first thought that you're right I found out that I was two times wrong :wink:
It has to be two 10nF in series. So I've got 5nF while the switch is open and 10nF when it's closed. I took this method to minimize switch popping as Mark Hammer once suggested it.

I did a layout for it containing all the mods I told above and a possibility to install a second gain-pot for IC2. I can send .zip packages to those who like to have one - just PM me.