Author Topic: pitch-shifting tube-driven vibrato unit  (Read 2213 times)

tubeswell

pitch-shifting tube-driven vibrato unit
« on: December 17, 2011, 01:00:25 PM »
Saw Steve Luckey's (over at the Hoffman forum) one a few months back and liked the sounds of that so I decided to try it for myself.

The unit uses a saturable reactor from a hammond organ, which is a kind of triple transformer array with one side of each of the three transformers wired in series with the other two and fed by an oscillator. The other sides of the transformers are utilised in feedback loops from the 12AU7 triodes. There are 4 sigma (phase shift/pitch/harmonic) controls (one for each 12AU7 triode), a feedback control, an output/bypass mixing control and the LFO controls. The unit is driven by 2 x 12AU7, 2 x 12AX7 and a 12DW7. There is a CF bypass so you can run the unit un-effected by turning down the output level control, which is wired with a dual gang pot that also serves and the 'dry' mix control when turned down. Schematic here:

http://ampgarage.com/forum/download.php?id=20207

Only delved into the tip of sounds so far but got several variations ranging from chorus to phase to vibrato to tremolo by tweaking the 4 sigma controls, and many variations in between. There are a few settings that sound quite magnatone-ish. I need to get a few .mp3s done.

(Not sure if I can upload pics here?)

iccaros

Re: pitch-shifting tube-driven vibrato unit
« Reply #1 on: December 17, 2011, 01:31:52 PM »
wonder if this could be done well with 6111 and 6112 submini tubes.
Voltage changes, and load lines change to keep clean.. As this is not trying to be an amp it would be simpler to keep those tubes clean..

iccaros

Re: pitch-shifting tube-driven vibrato unit
« Reply #2 on: December 17, 2011, 01:38:08 PM »
is there a place to get the reactor? or a suitable replacement?

tubeswell

Re: pitch-shifting tube-driven vibrato unit
« Reply #3 on: December 17, 2011, 01:51:25 PM »
The reactors are from old Hammond organ vibrato units. They come up on e-bay every so often.

tubeswell

Re: pitch-shifting tube-driven vibrato unit
« Reply #4 on: December 18, 2011, 01:44:50 AM »
Did some very rough sounds earlier this avo into garbageband not properly mic'd (mac built-in mic) and didn't get time to run through all the sounds, will try and find time later in the week. Guitar is a strat. Other amp is my PR clone. Please excuse the shoddy playing

Links follow:

http://music-electronics-forum.com/attachments/16501d1324188712-vibe-buggy.mp3   

http://music-electronics-forum.com/attachments/16502d1324188749-viberator-sky.mp3   

http://music-electronics-forum.com/attachments/16503d1324188799-black-sand-vibe.mp3   

http://music-electronics-forum.com/attachments/16504d1324188888-stray-vibe.mp3

tubeswell

Re: pitch-shifting tube-driven vibrato unit
« Reply #5 on: December 19, 2011, 05:44:41 PM »