? for Fender amp owners - Vibrato Noise

Joerg Hennig · Post by **Joerg Hennig** » 3 Apr 2003 11:10 am

I have a great sounding Fender Vibrosonic amp but the vibrato effect didn´t work when I bought it so they agreed at the store to fix it at no extra cost. It took a while and I got it back today. The vibrato now is there but it is accompanied by a faint "popping" noise that corresponds to the speed of the vibrato. It is not affected by the volume control. At bandstand volumes it is not even audible over the playing but nevertheless always there. Is this a common thing with older Fender amps or should I get it fixed again?

Regards, Joe H.

Brad Burch · Post by **Brad Burch** » 3 Apr 2003 12:14 pm

My late 70's Fender Twin does it too. I wouldn't call this a pop per say, it makes it almost sound like a digital processor or something. I have a vibrochamp that has a super vibrato and doesn't do this.

Gino Iorfida · Post by **Gino Iorfida** » 3 Apr 2003 12:38 pm

Well, it's only an issue with the 'larger' fender amps due to the use of the LDR for vibrato (vibrochamp uses different method)... you are picking up the sound of the neon lamp firing. There is a fix of strapping a small cap across the bulb, however that fix only works about less than half of the time. The best fix, is to ahve a tech reroute the wires in the amp... You never heard this on the older blackface fenders, but silverface fencers due to sloppier lead dress will show it.... yoru best option is to either 'deal with it' or be prepared for soem time in rerouting the wires

Bill Hatcher · Post by **Bill Hatcher** » 3 Apr 2003 12:42 pm

This is a common problem in Fender amps. Called "Vibrato ticking".

Use "Google" for a search engine (you will never use any other!!) and type in "Fender vibrato ticking". There will be several listings that will tell you how to repair this. All you do is add a cap from the 10meg resister. There will be a detailed description of how to do this and what value to use.

Buck Dilly · Post by **Buck Dilly** » 3 Apr 2003 1:32 pm

I have a Vibrosonic with the same problem. My tech did something which reduced it, and I amd sure it is failry simple. But don't expect to get rid of it. You just have to deal with it. It is a characteristic of the amp.

Gino Iorfida · Post by **Gino Iorfida** » 3 Apr 2003 4:27 pm

Bill,
I have done the cap (actually i install it on ALL Fenders I work on, but if the problem is due to lead dress (which is it 60% of the itme or more), then the only other recourse is clean that up, which is a pain, but sometimes is needed

Joerg Hennig · Post by **Joerg Hennig** » 4 Apr 2003 10:54 am

Thanks a lot guys, at least now I know mine is not the only one. Since the amp otherwise is really fine, I think I´ll leave it at that for now. I don´t use the vibrato a whole lot anyway... it´s great for "Night Life", for instance, but I have yet to find a band to perform that tune with...

Regards, Joe H.

Gino Iorfida · Post by **Gino Iorfida** » 4 Apr 2003 11:01 am

If you never use the vibrato, and want to be rid of the ticking. You can pull the 12ax7 that controls the trem. since it doesnt affect anything else (if you are looking at the back of the amp from left to right, you have the power tubes, the 12at7 phase inverter tube, then the trem. tube).

Joerg Hennig · Post by **Joerg Hennig** » 4 Apr 2003 2:40 pm

Gino, I don´t think that would make sense since the ticking occurs only when the vibrato is switched on with the footswitch, there isn´t any of it when it´s off. I want to keep the vibrato, I don´t use it a lot, but once in a while it sure is nice.

Joe H.

Gino Iorfida · Post by **Gino Iorfida** » 4 Apr 2003 3:10 pm

I was thinkign (shouldnt do that, ya know?) that you were NOT going to use the vibrato, and if you wanted to leave the footswitch at home etc, you could pull the tube. As for it only happening when the vibrato is on, that is correct, since the switch stops the oscillator. Just make sure to turn off the vibrato when not playing

Jay Ganz · Post by **Jay Ganz** » 5 Apr 2003 7:46 am

Well, I've noticed that different 12AX7's
(all of which are supposedly good) can
cause that "ticking". I just tried a few
until I found a quiet one. That was about it.

Bruce Derr · Post by **Bruce Derr** » 5 Apr 2003 11:31 am

My 1980 Deluxe Reverb had this problem. I went to add the extra cap in the vibrato circuit, only to find that it was already there, put there by Fender at the factory. They apparently started putting the cap into all the amps at some point.

The ticking went away when I tidied up the wiring a bit. The way to do this is to bunch the wires going to the vibrato tube together, and keep them as far as possible from any wires that carry signal. If a signal-carrying wire must pass near one of the wires in the vibrato circuit, position them at right angles to each other, to minimize coupling between the wires.

Gino Iorfida · Post by **Gino Iorfida** » 5 Apr 2003 2:58 pm

When tidying up the wires (silverface fenders were the worst for this), by cutting an inch or 2 off of allthe wires in the area to clean it up, I ended up cutign 1-2 feet fo total wire out of the amps.... then again, even then the extra wire was still probably cheaper than skilled laborers....

Bob Metzger · Post by **Bob Metzger** » 10 Apr 2003 3:50 pm

I have never had an amp where the cap fix didn't work (.022/600 volt or greater). I've seen it placed in two places on Fender amps but I think the best place is between the opto-iso/ 10meg point to ground. It's true that the BF amps had a much better wire routing method than the SF amp but I've got a BF amp on my bench as I write that ticks like crazy with stock and correctly routed wire. Obviously, Fender felt the cap was the route of least resistance (pun intended). I recommend the routing first, if you know what you're doing and the cap after.

Having said all that, this is not a critical part of the Fender circuit and if an amp has the extra cap or not makes little difference (except for the absence of 'the tick').

Bob M.<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Bob Metzger on 11 April 2003 at 04:30 AM.]</p></FONT>