5e9 tremolux cutting off when switching tremolo off - diyAudio
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Old 7th March 2012, 03:00 PM   #1
lulin is offline lulin  United Kingdom
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Default 5e9 tremolux cutting off when switching tremolo off

hi all
i ve just finished to built a 5e9 tremolux. sound great .only a problem. if i switch the tremolo off using the foot switch with the depth from 4 o clock (9) to max the sound cuts off. the tremolo works all the way. any idea ?
thank you!

ps: the circuit is standard appart from adding a negative feedback loop
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Old 7th March 2012, 05:11 PM   #2
kevinkr is offline kevinkr  United States
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Per forum directive I am moving this to Instruments & Amps. Please read the notice at the top of Tubes / Valves wrt musical instrument amps.
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Old 8th March 2012, 01:51 AM   #3
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Is there a 5E9 schematic? All I can find is 5E9A with a couple of notes about the 5E9 having a 5Y3 rectifier and a switch on the Depth control instead of the Speed control.

Check the voltage on pins 3 and 8 of the 12AX7. It's probably getting too high and the tube is cutting off, that means the plate voltage on pins 1 and 6 will go to B+. This is a very unusual tremolo circuit for Fender. This is the only model I think that used it. Try swapping the 12AY7 and the 12AX7 to see if the problem goes away. That will confirm that the phase inverter is getting biased off by the Depth control. The problem could be that B+ is too high or too low. Did you buy a kit or just assemble the amp from parts?

Best advice: Go here: Music Electronics Forum register and post question under Guitar Amps > Build Your Amp > Tweed. Someone there can help you.
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Old 8th March 2012, 07:04 AM   #4
Enzo is offline Enzo  United States
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Hi, LT.

I agree with Loudthud, the MEF he linked is all about guitar amps, while this forum is more about hifi. When people come to MEF with hifi questions, I send them here.


Meanwhile, and looking at the 5E9A, just how did you add the NFB? If I had to guess, I might think something about the NFB tie-in was causing the problem.

If you remove the trem tube, does the amp work as expected? Or does the footswitch STILL kill the sound?

Which leads me to ask, is that really a 10 MEG resistor you have from the phase inverter B+ supply down to the footswitch jack? Not 10 ohm or 10k.
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Old 9th March 2012, 05:40 AM   #5
lulin is offline lulin  United Kingdom
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thanks, I made this amp from scratch, board ,chassis etc... I' ve remove the feedback and still does the same and it s a 10 meg resistor I ll try without the trem tube and see.I ve double check wiring and it seems ok ,i ll check again and let you know findings and meanwhile I ll check out the other forum..thanKs for your help
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Old 9th March 2012, 09:47 AM   #6
Enzo is offline Enzo  United States
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10 meg resistor to WHERE?
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Old 9th March 2012, 04:14 PM   #7
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Does the amp cut out if the tremolo is disabled by the footswitch and the Depth control is adjusted?

I just noticed on the 5E9A layout that there is a note saying that the voltage on pin 8 of the tremolo tube (that's the cathode of the LFO side) should be 2.1V with Depth an minimum and 4.5V with Depth at Maximum. Frankly, that doesn't make any sense. I would expect something like that on pins 8 and 3 of the phase inverter tube.
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Old 12th March 2012, 02:10 PM   #8
lulin is offline lulin  United Kingdom
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Does the amp cut out if the tremolo is disabled by the footswitch and the Depth control is adjusted?

I just noticed on the 5E9A layout that there is a note saying that the voltage on pin 8 of the tremolo tube (that's the cathode of the LFO side) should be 2.1V with Depth an minimum and 4.5V with Depth at Maximum. Frankly, that doesn't make any sense. I would expect something like that on pins 8 and 3 of the phase inverter tube.

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that is what happens.the amp cut out when tremolo disabled by foot switch and depth from 4 o clock onward. and also as you say the voltage varied on the on pin 3 and 8 of phase inverter not on cathode of tremolo tube. i ve try the music electronic forum but no one has replied yet.i m keep double checking wiring and I can t find anything still. I didn t mention earlier but I ve changed the output power stage slightly by addiig two 470 ohms to decouple the screens of the power tubes. thanks again for your help
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