Double bass transducer problem

[N_Cook]

What is the likely cause of this problem.
Just as well I keep repair records as I met this amp 5 years ago with the
same untraceable fault. Owner and me had forgotten it re-appeared when he
used the bass with a different bass amp.
Previously reported as a fuzzy sound when he used the bass E string. This
time just playing the F on the bass E string , a rattly buzz, like a spiral
wound guitar string vibrating against a fret and loss of the actual F note.
I've not seen the bass or transducer , assuming its a piezo element - make
Ashworth transducers, what could cause this symptom, disappearing for 4
years? Both bass and amp have been around the world a few times on cruise
ships so perhaps excessive heat or humidity

 

[Sjouke Burry]

What is the likely cause of this problem.
Just as well I keep repair records as I met this amp 5 years ago with
the same untraceable fault. Owner and me had forgotten it re-appeared
when he used the bass with a different bass amp.
Previously reported as a fuzzy sound when he used the bass E string.
This time just playing the F on the bass E string , a rattly buzz,
like a spiral wound guitar string vibrating against a fret and loss of
the actual F note. I've not seen the bass or transducer , assuming its
a piezo element - make Ashworth transducers, what could cause this
symptom, disappearing for 4 years? Both bass and amp have been around
the world a few times on cruise ships so perhaps excessive heat or
humidity

Input dependend oscillations?
for retain freguencies and /or source impedances oscillations at certain
parts of the waveform.
Sounds just like you described.
And a change of source will make it appear/disappear.
Remedy: carefully changing the HF bandwidth a bit, and improve
dc power decoupling.
A small cap across inputs also is worth trying.

 

[tuinkabouter]

What is the likely cause of this problem.
Just as well I keep repair records as I met this amp 5 years ago with the
same untraceable fault. Owner and me had forgotten it re-appeared when he
used the bass with a different bass amp.
Previously reported as a fuzzy sound when he used the bass E string. This
time just playing the F on the bass E string , a rattly buzz, like a spiral
wound guitar string vibrating against a fret and loss of the actual F note.
I've not seen the bass or transducer , assuming its a piezo element - make
Ashworth transducers, what could cause this symptom, disappearing for 4
years? Both bass and amp have been around the world a few times on cruise
ships so perhaps excessive heat or humidity

Can he try another bass guitar?

 

[N_Cook]

"N_Cook" wrote in message
What is the likely cause of this problem.
Just as well I keep repair records as I met this amp 5 years ago with the
same untraceable fault. Owner and me had forgotten it re-appeared when he
used the bass with a different bass amp.
Previously reported as a fuzzy sound when he used the bass E string. This
time just playing the F on the bass E string , a rattly buzz, like a spiral
wound guitar string vibrating against a fret and loss of the actual F note.
I've not seen the bass or transducer , assuming its a piezo element - make
Ashworth transducers, what could cause this symptom, disappearing for 4
years? Both bass and amp have been around the world a few times on cruise
ships so perhaps excessive heat or humidity



On reflection, and assuming this is an acoustic Bass with a piezo pickup,
the most likely scenario is the Bass was feeding back through the PA.

Whatever, you seem to have no first hand evidence of this problem
whatsoever, and appear to be simply relaying what your customer has told you
is the problem.

In my experience, customers will cite all sorts of reasons for their
reported symptoms, almost all of which will be complete rubbish, because
they are simply not capable of making any sort of informed diagnosis.
That's your job.



Gareth.

I'll give him a rubbber doorstop to place under the spike , worth a try

 

[N_Cook]

Input dependend oscillations?
for retain freguencies and /or source impedances oscillations at certain
parts of the waveform.
Sounds just like you described.
And a change of source will make it appear/disappear.
Remedy: carefully changing the HF bandwidth a bit, and improve
dc power decoupling.
A small cap across inputs also is worth trying.

I'm trying to work out what HF means in terms of 44 to 44 Hz, but as the amp
is only used with an acoustic bass then a permanent adaption at the input is
possible

 

[N_Cook]

Can he try another bass guitar?

He was swapping pickup for a gig last night and also another amp and should
report back today

 

[N_Cook]

"N_Cook" wrote in message
What is the likely cause of this problem.
Just as well I keep repair records as I met this amp 5 years ago with the
same untraceable fault. Owner and me had forgotten it re-appeared when he
used the bass with a different bass amp.
Previously reported as a fuzzy sound when he used the bass E string. This
time just playing the F on the bass E string , a rattly buzz, like a spiral
wound guitar string vibrating against a fret and loss of the actual F note.
I've not seen the bass or transducer , assuming its a piezo element - make
Ashworth transducers, what could cause this symptom, disappearing for 4
years? Both bass and amp have been around the world a few times on cruise
ships so perhaps excessive heat or humidity




I would imagine the piezo pickup is not securely attached to the body.
This would no doubt cause it to rattle at a resonant frequency determined by
its mass and the properties of whatever fixing arrangement is partly (and
long term intermittently) securing it to the Bass.

Or alternatively, the pickup might be insecurely contained within some sort
of housing, and the rattling is the pickup in such a housing.

Or more alternatively, there is a battery powered pre-amp installed between
pickup and outside world. When the battery runs down, you can get all sorts
of weird stuff happening that you wouldn't immediately associate with a flat
battery.



Gareth.

I'll ask about battery, my only experience with piezo was a violin
transducer and no battery with that one

 

[N_Cook]

a&c

40 to 44 Hz

 

[N_Cook]

It looks as though it was due to owner sticking a bit of plastic tape
between transducer and the body of the bass, to stop the bridge moving - so
much for electronic repair