Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Double bass transducer problem

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


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Default Double bass transducer problem

"N_Cook" wrote in :

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.
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Default Double bass transducer problem



"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.

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Default Double bass transducer problem

On 1/10/2013 11:32 AM, N_Cook wrote:
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?

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Default Double bass transducer problem



"tuinkabouter" wrote in message ...

On 1/10/2013 11:32 AM, N_Cook wrote:
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?


Er, I've been assuming this is about a Double Bass, i.e. an acoustic upright
bass.

http://www.paddockorchestra.org/inde...ge=double_bass


Maybe I'm mistaken?





Gareth.



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Default Double bass transducer problem



"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.

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Default Double bass transducer problem

Gareth Magennis wrote in message
...


"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


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Default Double bass transducer problem

Sjouke Burry s@b wrote in message
2.10...
"N_Cook" wrote in :

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.


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


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Default Double bass transducer problem

tuinkabouter wrote in message
...
On 1/10/2013 11:32 AM, N_Cook wrote:
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?


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


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Default Double bass transducer problem

Gareth Magennis wrote in message
...


"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




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Default Double bass transducer problem

a&c

40 to 44 Hz





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Default Double bass transducer problem

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


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