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Old 30th April 2009, 04:10 PM   #1
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Default LME49811 + Sanken STD03N/P

Finally got the boards back --

Click the image to open in full size.

Schematic is here -- R2 is either in as a zero-ohm or out.

http://www.tech-diy.com/Amplifiers/L...811_Sanken.gif
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Old 1st May 2009, 07:17 PM   #2
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Dear jackinnj,

So happy to see someone else is experimenting with the LME chips with Sanken STD03N/P's

Please share your experience about sound quality, and share your bias experience, do you stick to the 40mA adviced by Sanken or you get over it?


One question, why is R12 needed? is it not sufficient enough to bias with only P1?


With best regards,
Bas
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Old 1st May 2009, 09:38 PM   #3
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The Source and Sink outputs need to pass current between themselves.
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Old 1st May 2009, 09:56 PM   #4
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Quote:
Originally posted by jackinnj
The Source and Sink outputs need to pass current between themselves.

Dear jackinnj,

But they will pass current already if you connect a resistor between the diode string in the STD03 in your case P1.
How high you bias the STD03's?
How do you like sound quality?

Looking forward to your response.

With best regards,
Bas
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Old 2nd May 2009, 12:45 AM   #5
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Quote:
Originally posted by Sebastiaan



Dear jackinnj,

But they will pass current already if you connect a resistor between the diode string in the STD03 in your case P1.
How high you bias the STD03's?
How do you like sound quality?

Looking forward to your response.

With best regards,
Bas
I couldn't set the bias to a low enough level without the resistor.

The diodes need 2.5mA for proper temperature compensation -- so you've got to fiddle with the value of R12 and P1. 820R is a starting value.
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Old 2nd May 2009, 02:19 AM   #6
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Quote:
Originally posted by jackinnj


I couldn't set the bias to a low enough level without the resistor.

The diodes need 2.5mA for proper temperature compensation -- so you've got to fiddle with the value of R12 and P1. 820R is a starting value.

Dear Jackinnj,

Clear I get it, thanks

With the LME49810 I got the specified 2,5mA with 1,1Kohm resistor between the bias pins.

Please keep us informed about how you like the sound quality.

With best regards,
Bas
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Old 2nd May 2009, 11:29 AM   #7
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Hello Bas,

In my experience with those Sankens, I get better performance with at least 60mA bias current (and the 2.5mA diode current as mentioned). The recommended 40mA bias is best for thermal tracking, but at 60mA the xover distortion is much lower in peak amplitude, and thermal tracking is still pretty good - I have had no issues with thermal runaway at all.

Jan Didden
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Old 2nd May 2009, 12:01 PM   #8
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yes, Jan -- I've been running them "hot" with no issues -- but I haven't been able to actually listen to the things.

It would be nice to have a better idea of the configuration of the VAS stage -- as it is now you're dealing with a bit of a black box.
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Old 2nd May 2009, 03:28 PM   #9
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Maybe this is a little clearer -- I've shown with XMM1 to measure the current across the tempco diodes and XMM2 to measure the bias current:

http://www.tech-diy.com/Amplifiers/L...11_Sanken2.gif

There are a couple permutations of the compensation circuitry -- but all the folks who worked on it at national have been laid off!
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Old 2nd May 2009, 08:56 PM   #10
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Quote:
Originally posted by janneman
Hello Bas,
art to become
In my experience with those Sankens, I get better performance with at least 60mA bias current (and the 2.5mA diode current as mentioned). The recommended 40mA bias is best for thermal tracking, but at 60mA the xover distortion is much lower in peak amplitude, and thermal tracking is still pretty good - I have had no issues with thermal runaway at all.

Jan Didden
Dear Jan,

Yes I am agree. I use Re's of 0,1 ohm. and run the Sanken's on 80mA (which is a voltage of only 8mV between the NPN and NPN Re's).

Douglas Self advice 25mV. over the Re no matter which application. I tired and IMD get twice lower, but then Thermal run away starts to become an issue with the STD03's sadly enough. So that is not really an option in order to benefit the simple thermal compensated bias method of the STD03's

With best regards,
Bas
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