New EF86 Special build

[sixstringer]

I was feeling all proud of myself for coming up with the relay "stick", only to discover that Mojo and SkipzCircuits already have them available. The SkipzCircuits is especially cool with 2 channels of FET switching on a tiny board.

[tele_player]

I was feeling all proud of myself for coming up with the relay "stick", only to discover that Mojo and SkipzCircuits already have them available. The SkipzCircuits is especially cool with 2 channels of FET switching on a tiny board.

The Skipz CHSW only does one DPDT relay, yours does two. I didn't check out the other products.

But yes, optical FET switches are nice, if their ON and OFF resistance characteristics work for your application. For the purist, an electromechanical relay is probably superior.

Robert

[sixstringer]

Almost finished with the 86 Special x 2. There is a slight 120Hz hum that increases when I plug in the 2nd EL-84 power tube and decreases when I add more filtering. This hum is not effected by any control setting changes or by plugging in or removing a signal. Is the best way to deal with this hum by increasing filtering? Will it hurt the transformer to up the value of the filter?

Also, the relay switching works perfectly on the PAB channel and works but needs a little sorting for the OD channel. The control panel design stills need to be completed.

[10thTx]

That is a VERY cool amp! Thanks for sharing the photos.

Would love to hear some sound clips.

With respect, 10thtx

[Thomas_H]

Wow amazing,

that's beautiful, inside out!
like this vintage look, looks really nice.

[mat]

That amp looks stunning! Great job. I still have quite a lot of hum on my build. Have to find time to troubleshoot it some day.

Would also like to hear the amp very much. What Jensen model is that speaker ?

[sixstringer]

Thanks for the comments and kind words. I ordered and received an Eminence Delta Pro 12A (as recommended) only to discover it's too large for the cabinet. I also tried a '61 Jensen P12N (like new, out of an organ), and it wouldn't fit either.... so, I tried couple of different Jensen ceramic speakers and they fit without issue, but they did not bring much to the party, BUT while searching for a workable solution, I plugged in a Jensen Jet Falcon 10 and it sounded really good. I'm ordering the 12" version: Jet Jet Falcon 12 and I hope it will sound as cool. I have had great luck with that speaker as a replacement for various Fender amps. I have an RA (return number) for the Eminence speaker and plan to send it back after testing the Jensen speaker. Otherwise, I'll build a deeper cabinet and keep the Delta Pro. Regarding the hum, do you think I can add more filtering to the power section without damaging anything? Also, I'll see about a sound file.
Thanks for your help.

[mat]

I dont know how the increased filtering could damage the amp. Here are much more knowlidgeable builders here. I hope someone of them will have answer for your question.
I tried several cap values in power section on my build and listened what sounded and more likely felt best while playing. Nowdays I kind of like saggy amps.

[Structo]

Nice looking build!

[sixstringer]

Thank you. I think the Jensen Jet 12 is a bit better (more range and tighter bottom-end) than the Jensen Classic C12N, although it's not as dramatic as I had suspected it might be. I will compare them at higher volume. I found a lot of the noise issues I was having was from the relay switching of the OD channel, which was not working correctly anyway so I disconnected it for now. It would be nice to have more gain (and sustain) from the EF-86, so I'll see about adjusting that. I noted that there was a fair amount of conversation about tweaking Mat's amp, I will study that thread. I would be happy for any input you could give.

There is still a little 120Hz noise, slightly more with the OD engaged (as you would expect) but it's not unworkable.

[chopstuck]

Robert, thanks for your input. I had the OD drive coming off the wrong lug off the drive pot as well. I had to move the 1 meg ground reference to the wiper and BAM, my EF 86 Special sounds great for the first time ever.


Marc