Thinking out loud here, let me know if I am being rational.
I thought if I check the AC amplitude with pink noise at each speaker input terminal and compare values with my volume control set at normal listening level, if i see an amplitude delta between the two channels, I could adjust the bias settings to equalize the outputs,
I have a dual channel oscilloscope to do this with.
Seems simple, what do you all think?
Tweak i must.....
I thought if I check the AC amplitude with pink noise at each speaker input terminal and compare values with my volume control set at normal listening level, if i see an amplitude delta between the two channels, I could adjust the bias settings to equalize the outputs,
I have a dual channel oscilloscope to do this with.
Seems simple, what do you all think?
Tweak i must.....
Amplifier bias is not a volume control. Do not attempt that.
Most imbalances are either acoustical, or in the volume control itself.
A turntable can also be a little off balance.
Most imbalances are either acoustical, or in the volume control itself.
A turntable can also be a little off balance.
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Tweaking the bias with the aim of changing level is a sure fire way of destroying the amp and possibly your speakers as well.
Try moving the speakers further from the wall and adjusting the toe in. Move you listening position.
Try moving the speakers further from the wall and adjusting the toe in. Move you listening position.
Keep a video camera pointed at the output stage so you don't miss seeing the magic smoke.
I now have a .1mv diference with my bias settings,
10.1mv vs 10.2 mv with 10.0 mv being optimum.
Trying to compensate for the resitance difference of the emitter bases.
Emitter Currents are now equal.
Sounds great.....just thinking i could go a step further down line,
Again thanks for all your insights.
10.1mv vs 10.2 mv with 10.0 mv being optimum.
Trying to compensate for the resitance difference of the emitter bases.
Emitter Currents are now equal.
Sounds great.....just thinking i could go a step further down line,
Again thanks for all your insights.
13.0 and 13.3mv., sound was definitely louder in right channel)higher value) vs left. service manual recommends 10mv......
At 10.2 and 10.3mv, sounds seems balanced....
At 10.2 and 10.3mv, sounds seems balanced....
The output stage bias controls are not gain controls.
An output stage has unity gain, regardless of its bias setting.
An output stage has unity gain, regardless of its bias setting.
This is my understanding of integrated amp,
music signal enters pre amp, gain is controlled with volume control and balance control,this signal goes thru output stages, where the bias adjustnent for the final stage before output to speakers...
music signal enters pre amp, gain is controlled with volume control and balance control,this signal goes thru output stages, where the bias adjustnent for the final stage before output to speakers...
The bias needs setting carefully while taking measurements of standing current, get it wrong and you can easily blow the output devices (or if you are lucky some fuses/protection). Think of it like playing with the lean/rich setting of a jet engine while flying - you'll end up spitting molten turbine blades and stators out the back as likely as not!!
The vol is at zero, input is aux, i monitor the bias volt with dvm,
my tech, who is a tube guy, set the bias 3mv higher than recommended,
said things were fine.
i clocked the bias voltage back to the service manual values...
i then measured the emitter resistance;
which gave me the current values.
hence the .1mv difference in bias settings.
to equalize the current.
This is faulty thinking?
my tech, who is a tube guy, set the bias 3mv higher than recommended,
said things were fine.
i clocked the bias voltage back to the service manual values...
i then measured the emitter resistance;
which gave me the current values.
hence the .1mv difference in bias settings.
to equalize the current.
This is faulty thinking?