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Old 5th October 2011, 03:09 PM   #221
generg is offline generg  Germany
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Originally Posted by Backbones View Post
Can we say that once the 1V across R10 and R11 have been achieved via P1 and P2 then we can adjust and listen to the variations using P3 without going back to adjust P1 and P2 each time?
Chris
Difficult, already 60mV offset change, changes the distortion spectrum clearly

Indeed using a cap in front of the small j-FETs, isolating the pot dc wise from them, makes the offset more stable, when turning on the volume.

And forget the wish to cancel k2 completely, you can do it only for one position.
Or let us say you can minimize it for a region....of volume.

And I had at the moment no possibility to hear at the same time over the speakers music when changing P3.

I ended up with a constellation, low volume more k2 than k3 and at higher levels more k3 than k2.

I treated my output stage, (F4 like, with one pair and bias network with an higher impedance) by paralleling source resistors from 3-7 Ohm and finding the right side I could reduce k2 considerably.

Nelson did it with his F5, in the pictures of 6moons you can see a paralleled 2 ohm resistor.

All very interesting.....
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Old 5th October 2011, 03:22 PM   #222
Backbones is offline Backbones  United Kingdom
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And I had at the moment no possibility to hear at the same time over the speakers music when changing P3.
Are you saying that you can't actually hear any difference when altering P3?
Chris
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Old 5th October 2011, 03:24 PM   #223
Botte is offline Botte  United States
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Originally Posted by generg View Post
I treated my output stage, (F4 like, with one pair and bias network with an higher impedance) by paralleling source resistors from 3-7 Ohm and finding the right side I could reduce k2 considerably.

Nelson did it with his F5, in the pictures of 6moons you can see a paralleled 2 ohm resistor.

All very interesting.....
Thatís easy to do with one pair and itís a little more challenging with 12 pr.

See http://www.diyaudio.com/forums/pass-...ml#post2733726
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Old 5th October 2011, 04:43 PM   #224
generg is offline generg  Germany
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Originally Posted by Botte View Post
Thatís easy to do with one pair and itís a little more challenging with 12 pr.

See http://www.diyaudio.com/forums/pass-...ml#post2733726
You are soooooooo right!
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Old 5th October 2011, 08:01 PM   #225
generg is offline generg  Germany
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Are you saying that you can't actually hear any difference when altering P3?
Chris
My BA-3 and my F4 are now in the room with the PC, speakers are in the other room.

Changing k2 and hearing is a task for the next days....
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Old 5th October 2011, 08:03 PM   #226
generg is offline generg  Germany
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Thatís easy to do with one pair and itís a little more challenging with 12 pr.

See http://www.diyaudio.com/forums/pass-...ml#post2733726
Incredible! Respect!
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Old 6th October 2011, 01:33 PM   #227
Backbones is offline Backbones  United Kingdom
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Botte, what product are you using? I am in the market. Thanks.
Hi Mike,
Thanks for organising everything. Voltage reg boards and components arrived this morning.
Chris
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Old 6th October 2011, 01:46 PM   #228
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Hi Mike,
Thanks for organising everything. Voltage reg boards and components arrived this morning.
Chris
No problem, but you posted in the wrong thread!
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Old 6th October 2011, 02:02 PM   #229
generg is offline generg  Germany
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Hi, hi......
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Old 6th October 2011, 02:15 PM   #230
generg is offline generg  Germany
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I have now finished the first complete round of the distortion pleasure....

- I treated the BA-3 and the F4 (without J-fets and one pair only) seperately......

- on both gears in one channel it was easier to cancel the k2 than in the other.....

- I can only speculate the reasons...... bigger mismatch of Semis.....?

At any case the reduction was clearly possible!

I heard Cassandra Wilson afterwards, not an easy task for amps and speakers, heavy bass and crazy rythms.........

I found outlines and the picture being better....

and I think driving Lowthers with these NFB gears is a good idea, they were never before so tame.........

happy generg
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