Divided by Thirteen CeeJay Eleven

Tube or solid-state, this section goes to eleven!

Re: Divided by Thirteen CeeJay Eleven

Postby darkbluemurder » 20 Sep 2017, 15:58

The incomplete chassis lay in my basement for more than one year but recently I picked it up again and it is now much closer to finishing. Transformers are wired and the populated board is in. Need to wire the tube sockets, pots and jacks. Then on to final testing. I am looking very much forward to it.

Cheers Stephan
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Re: Divided by Thirteen CeeJay Eleven

Postby darkbluemurder » 27 Sep 2017, 13:30

Got mine finished but without the boost switch for now. It sounds pretty good so far. I need to replace the V1 socket as it is flaky and does not make good contact to pins 6 and 8 especially. That amp is quite loud and bright - I guess this is due to the 100pf bright cap. I used ceramic caps for the bright and anti-bright caps but I just saw in the pictures that the original uses silver mica caps. Otherwise I used carbon film resistors for the plates and the signal path and ERO Roederstein caps. I played this through a cab with a WGS Invader 50.

I will definitely implement the boost switch as I would welcome more clean headroom. I also consider making the bright cap switchable - maybe also going 47pf fixed plus 250pf on the switch.

Again, thanks for working out the schematic.

Cheers Stephan
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Re: Divided by Thirteen CeeJay Eleven

Postby darkbluemurder » 28 Sep 2017, 07:41

Yesterday I changed the flaky tube socket and implemented the boost switch which is a nice addition and does what I expected it to do.

I used an 18W power transformer and a Mercury Magnetics Deluxe Reverb transformer. I first tried the amp with a 5Y3 rectifier, which gave me 330V on the plates and 300V on the screens of the 6V6s. I then discovered that I still had a GZ34 in my tube stash and tried that. While I did not measure the voltages I liked the amp with the GZ34 a lot more - more punch, more sustain, and a cleaner tone at lower levels.

I stayed close to the schem (except for adding a 25kB mid control instead of the fixed 6k8 mid resistor) - no additional grid stopper before the cathodyne as I did not feel it was necessary. I can turn up both the volume and the master volume and it does not fold - not even with the boost on. This thing sounds great - a bit like a tweedish Trainwreck. It sounds great for bass guitar with an appropriate cab, too, even though it does not have a lot of headroom, but a viable option for recording and practice.

Cheers Stephan
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