I'm getting distortion in the left channel on my Luxman amp. It works fine
with headphones but not with speakers. The distortion is a big problem on
the left side with speakers. The bias on the tubes is fine and I have tried
switching the tubes but it hasn't help, so I know it's the amp. Does anyone
know what it might be? Thanks.

"AW" wrote in message
news:eCLZd.8141$oa6.3933@trnddc07...
I'm getting distortion in the left channel on my Luxman amp. It works fine
with headphones but not with speakers. The distortion is a big problem on
the left side with speakers. The bias on the tubes is fine and I have
tried
switching the tubes but it hasn't help, so I know it's the amp. Does
anyone
know what it might be? Thanks.

**You need to supply a whole bunch more information.

Such as:

The model # of the amp.
The types of tubes used.
The Voltages on those tubes.
What sort of "distortion" is involved (as observed on a CRO.
Et al.


--
Trevor Wilson
www.rageaudio.com.au

AW wrote:

I'm getting distortion in the left channel on my Luxman amp. It works fine
with headphones but not with speakers. The distortion is a big problem on
the left side with speakers. The bias on the tubes is fine and I have tried
switching the tubes but it hasn't help, so I know it's the amp. Does anyone
know what it might be? Thanks.

I have a Luxman with each of the two OPTs with shorted turns,
one gives 1/2 power, the other about 1/4 power and thd is bad.

Measure the primary inductance of each OPT at 50 Hz,
with the amp not connected to the mains, and no load connected,
and with an external voltage of 6.3 v from a heater supply
used in series with a 1k resistor between each anode and 0V.
You should measure the AC impedance of each 1/2 primary
as being well above RLa-a at 50/60 Hz, and the same for
each OPT.
The current flow in the 1k R can be calculated, abd the voltage across the 1/2
primary
divided by the I flow in the 1K gives an idea of the impedance input to the
anode connection
of the OPT.
If one OPT measures a lot lower Z than the other, its stuffed, and a new OPT is
the only cure.

Let's hope its something else.

Patrick Turner.

Luxman LX-33
4 EL34's, 2 12AU7's (using 5814A and 5814WA,) 1 6AQ8, 4 12AX7's (using
5751's)
I am using the lowest possible bias settings (average 30-35mA on each tube?)
I don't have an oscilliscope... in the left channel when I turn it up the
sound is weak and scratchy, and sounds thin.

"Trevor Wilson" wrote in message
...

"AW" wrote in message
news:eCLZd.8141$oa6.3933@trnddc07...
I'm getting distortion in the left channel on my Luxman amp. It works
fine
with headphones but not with speakers. The distortion is a big problem
on
the left side with speakers. The bias on the tubes is fine and I have
tried
switching the tubes but it hasn't help, so I know it's the amp. Does
anyone
know what it might be? Thanks.

**You need to supply a whole bunch more information.

Such as:

The model # of the amp.
The types of tubes used.
The Voltages on those tubes.
What sort of "distortion" is involved (as observed on a CRO.
Et al.


--
Trevor Wilson
www.rageaudio.com.au

AW wrote:

Luxman LX-33
4 EL34's, 2 12AU7's (using 5814A and 5814WA,) 1 6AQ8, 4 12AX7's (using
5751's)
I am using the lowest possible bias settings (average 30-35mA on each tube?)
I don't have an oscilliscope... in the left channel when I turn it up the
sound is weak and scratchy, and sounds thin.

Use a test signal at 100 Hz and at 2 volts output into 8 ohms.
then use 1 kHz.
Check all the signal voltages in the amp on both channels,
and determine the tube gain for each tube.
Both channels should give the same tube gain for all signals.

But if you have a shorted turn in an OPT, the 100 Hz signal
will give you low gain in the output tubes, and the thin sound which
has mainly HF content.

If you can't understand WTF you are trying to measure, take the damn amp to a
tech
who understands how to figure it out.

Patrick Turner.



"Trevor Wilson" wrote in message
...

"AW" wrote in message
news:eCLZd.8141$oa6.3933@trnddc07...
I'm getting distortion in the left channel on my Luxman amp. It works
fine
with headphones but not with speakers. The distortion is a big problem
on
the left side with speakers. The bias on the tubes is fine and I have
tried
switching the tubes but it hasn't help, so I know it's the amp. Does
anyone
know what it might be? Thanks.

**You need to supply a whole bunch more information.

Such as:

The model # of the amp.
The types of tubes used.
The Voltages on those tubes.
What sort of "distortion" is involved (as observed on a CRO.
Et al.


--
Trevor Wilson
www.rageaudio.com.au

I took the amp to a tech today and I gave him a printout of your post.

"Patrick Turner" wrote in message
...


AW wrote:

Luxman LX-33
4 EL34's, 2 12AU7's (using 5814A and 5814WA,) 1 6AQ8, 4 12AX7's (using
5751's)
I am using the lowest possible bias settings (average 30-35mA on each
tube?)
I don't have an oscilliscope... in the left channel when I turn it up
the
sound is weak and scratchy, and sounds thin.

Use a test signal at 100 Hz and at 2 volts output into 8 ohms.
then use 1 kHz.
Check all the signal voltages in the amp on both channels,
and determine the tube gain for each tube.
Both channels should give the same tube gain for all signals.

But if you have a shorted turn in an OPT, the 100 Hz signal
will give you low gain in the output tubes, and the thin sound which
has mainly HF content.

If you can't understand WTF you are trying to measure, take the damn amp
to a
tech
who understands how to figure it out.

Patrick Turner.



"Trevor Wilson" wrote in message
...

"AW" wrote in message
news:eCLZd.8141$oa6.3933@trnddc07...
I'm getting distortion in the left channel on my Luxman amp. It
works
fine
with headphones but not with speakers. The distortion is a big
problem
on
the left side with speakers. The bias on the tubes is fine and I
have
tried
switching the tubes but it hasn't help, so I know it's the amp. Does
anyone
know what it might be? Thanks.

**You need to supply a whole bunch more information.

Such as:

The model # of the amp.
The types of tubes used.
The Voltages on those tubes.
What sort of "distortion" is involved (as observed on a CRO.
Et al.


--
Trevor Wilson
www.rageaudio.com.au