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Old 5th January 2012, 07:39 PM   #711
M Gregg is offline M Gregg  United Kingdom
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Thinking,

I have the zener voltage set so with one heater its not in conduction at idle..
With two heaters its in conduction at idle by a couple of volts..

Perhaps that is the difference..

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Old 5th January 2012, 08:47 PM   #712
M Gregg is offline M Gregg  United Kingdom
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The mozener,

Does clamp the cap voltage and prevents the increase of cap voltage when two heaters are switched in... << just an observation

The only thing I can think of is my speakers must drive well with just a few watts.. I have no other explanation...

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Old 5th January 2012, 09:04 PM   #713
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You´re only benefitting from the constant voltage when running it hard.

At low OP it should perform the same as katodbias.
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Old 5th January 2012, 09:21 PM   #714
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by flatheadmurre View Post
You´re only benefitting from the constant voltage when running it hard.

At low OP it should perform the same as katodbias.
I agree ,,if the voltage across the cap was to remain the same ie change with number of heaters running... 40v (one heater) 46V(two heaters)<<<resistor bias

If the voltage across the cap/resistor remains the same voltage more current must be flowing through the FET to reduce the voltage across the resistor?

This must effect the bias at idle?

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Old 5th January 2012, 09:27 PM   #715
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When running amp at low power you´re in class A.

When running it harder towards AB the mozener keeps bias from drifting giving less distorsion.
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Old 5th January 2012, 09:31 PM   #716
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by flatheadmurre View Post
When running amp at low power you´re in class A.

When running it harder towards AB the mozener keeps bias from drifting giving less distorsion.
This does does show..the amp is cleaner much futher up the volume scale..

Its a bit to far for my speakers .....

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Old 5th January 2012, 09:40 PM   #717
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What are the ratings of the speakers ?

You´re only putting out ~10W.
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Old 5th January 2012, 09:52 PM   #718
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by flatheadmurre View Post
What are the ratings of the speakers ?

You´re only putting out ~10W.
I think they are 20W..I know they should be OK...Its just the bass really moves the cones..

Not sure if these are exactly the same generation but very close ..

http://www.madisoundspeakerstore.com...-4-full-range/

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Old 5th January 2012, 10:05 PM   #719
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Yes it´s a big difference in current available for driving the bass.

A transformer based amp has less in the lower region.

I expect my new PSU to give even better result.

Last edited by flatheadmurre; 5th January 2012 at 10:16 PM.
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Old 5th January 2012, 10:44 PM   #720
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Worth remembering the Impedance presented to the amp by the speaker at or near its freq of resonance, --for the Alpair 7 70 Hz, its many times the DC or quoted nominal impedance...

For the Alpair, its approaching something like 50 ohms at 70 Hz, therefore an easier load for the amp and more effective power can be realised.....
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