P
Patrick Hogan
Hi groups,
I have a couple of questions to ask about my Trace Elliot BLX-80 bass
guitar amplifier, but I suspect the questions may also be general to all
guitar amps.
I've been having various reliability problems with the amp, which
manifest in the form of a loud hum through the speaker and crackling and
buzzing that normally settles down after an hour of usage.
I hooked my ocilloscope up to the output (without the speaker connected)
and found that the output was clipping at 3v peak-to-peak. This is with
the input gain set at 3/10 and the output gain set at 4/10, i.e. pretty low.
The two main output transistors also got extremely hot VERY quickly when
playing, i.e. within seconds, again without the speaker being connected.
In addition to this, they also made a buzzing noise when output was
driven through them, the volume of the buzz in proportion to the
peak-to-peak voltage on the output.
My questions are:
1) Should the amp be clipping at such a low gain setting?
2) Should the output transistors be getting so hot and making a noise?
3) Is this expected behaviour if the speaker isn't connected?
4) I have already replaced the large capacitors on the power supply.
Perhaps the transistors ought to be replaced too?
Many thanks in advance,
Patrick
I have a couple of questions to ask about my Trace Elliot BLX-80 bass
guitar amplifier, but I suspect the questions may also be general to all
guitar amps.
I've been having various reliability problems with the amp, which
manifest in the form of a loud hum through the speaker and crackling and
buzzing that normally settles down after an hour of usage.
I hooked my ocilloscope up to the output (without the speaker connected)
and found that the output was clipping at 3v peak-to-peak. This is with
the input gain set at 3/10 and the output gain set at 4/10, i.e. pretty low.
The two main output transistors also got extremely hot VERY quickly when
playing, i.e. within seconds, again without the speaker being connected.
In addition to this, they also made a buzzing noise when output was
driven through them, the volume of the buzz in proportion to the
peak-to-peak voltage on the output.
My questions are:
1) Should the amp be clipping at such a low gain setting?
2) Should the output transistors be getting so hot and making a noise?
3) Is this expected behaviour if the speaker isn't connected?
4) I have already replaced the large capacitors on the power supply.
Perhaps the transistors ought to be replaced too?
Many thanks in advance,
Patrick
