Pickup Problems

Andy Howell · #1 10-18-2014, 03:42 AM

I have a Fishman under saddle installed in one of my guitars. Over the last few months it has developed a low hum which I've been able to deal with using a notch filter. It is now terrible.

I will take the opportunity to replace the Pickup but I'm wondering if there is a quick fix.

This seems to be an earth/ground issue. Could it be that something has become unscrewed in the guitar itself?

MarkF_48 · #2 10-18-2014, 06:03 AM

May not be your problem, but I ran into something similar with an older Ibanez guitar with an under saddle pickup. It as well had developed a hum and also lost some of the output from the higher strings. Notch filter was sort of a band-aid for me as well, plus backing off the bass EQ. This occurred after I had done a string change. A bit of Googling and it seems that when I did the string change the saddle had tilted a bit when tensioning up the strings and wasn't making good physical contact to the piezo pickup. The saddle wasn't flat on the piezo, but angled up on an edge. Because of this I had to increase the gain of the amp and in doing so also amplified some of the hum that was usually way down in the mud and not noticeable. I was able to sort of fix this by loosening and re-tensioning the strings, but I'm still not totally happy with it. I was thinking of starting a separate thread on this saddle/piezo problem.
Again, may not be the problem you have, but maybe worth a look.

pieterh · #3 10-19-2014, 04:16 PM

I wonder if you have the same problem I had a year or two ago, namely I scratched the surface of the pickup while trying to sort out saddle height. Does the hum disappear when you touch any metal parts, particularly the output jack?

I solved it short-term by putting a piece of kitchen foil, the same width as the saddle slot, between the pickup and the saddle. Worked perfectly!

Andy Howell · #4 10-20-2014, 12:59 AM

Quote:

Originally Posted by pieterh

I wonder if you have the same problem I had a year or two ago, namely I scratched the surface of the pickup while trying to sort out saddle height. Does the hum disappear when you touch any metal parts, particularly the output jack?

I solved it short-term by putting a piece of kitchen foil, the same width as the saddle slot, between the pickup and the saddle. Worked perfectly!

I've not removed the saddle but the effect you describe is similar. Another player has suggested saddle problems and I wonder if I've damaged the pickup through thumping and frailing?

joeguam · #5 10-20-2014, 01:18 AM

This is a common problem that occurs when the shielding of the under saddle piezo has been damaged in any way and is not grounding properly. If you touch the metal output jack and the humming stops, this is very likely your problem.

Some suggestions:
1. Try the foil suggestion mentioned earlier, but as was said, this is a band aid.
2. Call Fishman, nicely explain your problem, and they might send you a replacement piezo, but you'll hand to solder off the old one to the endpin jack, and then solder the new one on.
3. If you want to permanently fix the problem and if the foil fix does solve your problem temporarily, my best suggestion is to purchase "shielding paint" from somewhere like stewmac and paint it over the damaged surface of the piezo. This is not guaranteed to work, but it's the best chance.

Good luck.

pieterh · #6 10-20-2014, 05:33 AM

The OP may not have to any soldering - the newer Matrix jack preamps have a screw fitting to secure the wire from the pickup element.

I agree the foil solution is a temporary band-aid, but if the hum disappears using foil as a shield then at least we've determined where the problem is. If a damaged shield is the problem I imagine one could use some shielding paint to repair the damage though if the saddle has never been removed I would imagine it would be safer in the long run with a new element.

Andy Howell · #7 10-20-2014, 01:28 PM

Thanks folks it seems pretty likely that the pickup is damaged - it is 15 years old.

I've arranged to have it taken out and replaced by a local luthier - I just have to decide between Highlander and K&K (verging towards K&K)

jseth · #8 10-20-2014, 01:54 PM

Andy, those UST pickups last a long time, but they will eventually give out... I had the same ting happen with my 12 string (Fishman Matrix Acoustic Natural); the only thing to do was to buy a new element for the system - mine had the non-adjustable preamp on the endpin...

Curiously enough, the exact same unit in my 6 string never did go out on me, and it predated the 12 string pickup by at least 6 months... go figure.

I have since replaced both of those with an Anthem SL, which I like a whole lot.