Problem with amp tremolo

[mdancakster]

Hello there,

I have a problem with tremolo in my Tremolux. The pulses are really strongly audible (ticking) if the tremolo is engaged/on (even if thereīs no signal from the guitar) and I donīt know whatīs going on. Itīs the tweed 5e9A schematics but I finally changed the paraphase PI for that of tweed deluxe 5e3 because of better overall sound (as in EC Tremolux circuit – cathodyne PI); if the circuit was the original one (5e9A) everything with the tremolo was OK. After changing the PI scheme the problem with tremolo occurred. All the measured voltages values in tremolo are + or - 20% of the original 5e9A schematics. Iīve already tried to change the tremolo valve for another three but nothing changed). Any suggestions? Many thanks.

Regards, Martin

tremolux_5e9a.pdf

[bob p]

You've got *FIVE* different threads open with the same subject. That won't get you a quicker answer around here. Please choose one thread and abandon the others. IMO the most appropriate location for this thread is in Maintenance and Repairs, so I'd recommend that nobody posts in response to this thread, and instead responds only to this one:

Problem with amp tremolo

[bob p]

from one of the duplicate threads, here's the schematic.

[dmeek]

Here is a bulletin on the problem. No. 2 worked for me last time- Bunch the leads tightly from the tremolo tube.


http://music-electronics-forum.com/a...1&d=1519161815

[Chuck H]

Notice that the new PI has only the driving triode biased with a 1.5k resistor. The paraphase (that you said worked fine) had TWO triodes biased with a 1.5k resistor. That's twice the current through the resistor, and therefor a higher standing DC voltage than the single triode. That means the single triode of the new circuit is biased hotter. I think the ticking you hear may be the trem circuit slamming the driver triode into cutoff and saturation, causing abrupt DC shifts rather than a clean sine wave making a smooth warming/cooling effect. If you raise the cathode resistor on the driving triode you will lose gain, for better or worse I suppose. If you divide more shift from the trem circuit you'll reduce the tremolo effect. If the trem with the new PI circuit is ample I would try the latter. Increase the value of the 2.7k resistor connecting the trem circuit and the driver cathode. Maybe use a 10k pot as a variable resistor temporarily and see if you can find a value that gives you adequate trem function and stops the ticking.

[bob p]

Eureka! Now that the threads have been merged, I've finally beaten Enzo at the multiple-posting game! Yippee!!

[Enzo]

Oh yeah?

[Enzo]

Oh yeah?





etc.

[mdancakster]

Problem with amp tremolo

Many thanks Chuck,
seems there's some logic in your answer.. I must say that I've already tried to increase 1500 ohm cathode resistor and it influenced the overall gain of the amp.. so it's not a good way for me (BTW also in the EC tremolux there's 1k5).. however it sounds like a good idea to try 2k7 or 10k variable resistor (which is not included in the original scheme).. could you explain more closely where exactly I should wire it.. just to be sure I will do it right? one more think what you mean by the division of the shift from the trem circuit? many thank, regards, Martin.

[mdancakster]

Many thanks Chuck,
seems there's some logic in your answer.. I must say that I've already tried to increase 1500 ohm cathode resistor and it influenced the overall gain of the amp.. so it's not a good way for me (BTW also in the EC tremolux there's 1k5).. however it sounds like a good idea to try 2k7 or 10k variable resistor (which is not included in the original scheme).. could you explain more closely where exactly I should wire it.. just to be sure I will do it right? one more think what you mean by the division of the shift from the trem circuit? many thank, regards, Martin.

[Chuck H]

I've considered more carefully and this is what I can offer. In reference to the picture below:

With the amp idling and the tremolo switched off measure the DC voltage at the cathode pin connection of the circled resistor. Write it down.

Now connect a 10k pot across the 3.3k resistor as shown. Adjust the pot to see if it stops the ticking. If it does, be sure it is adjusted until it JUST stops the ticking and not more.

DO NOT ADJUST OR REMOVE THE POT.

Test amp for tremolo effect and gain.

Report back

[mdancakster]

sorry to bother you again but somehow I can't open the attachment in your thread in forum.. would you be so kind to send me the picture via email? Many thanks. Martin

[Justin Thomas]

You may want to use the Private Message feature to give out email addresses, phone numbers, addresses, etc. These threads show up in Google searches. Just an FYI. You can edit it out later, but there may be a time limit.

Justin

[bob p]

good point. 24 hours to edit, then your email address will be there forever.

[Chuck H]

I'm trying to figure out how to attach full size images, but I'm not the sharpest pencil in the box. Maybe someone here can give a tutorial?

Anyway... Martin, try right clicking the thumbnail and selecting "open in new tab".

And get your address off the public format. Just click edit and back it out, then click save.