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Old 16th May 2012, 08:48 AM   #1
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Default Looking for discrete high performance linestage design with 12v rails

Been searcing the forums to no avail....lookingfor a high performance linestage that will run off 12v +/- rails that is fairly simple to implement. Please let me knowif you habe a good design/schematic.
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Old 16th May 2012, 09:15 AM   #2
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If there is no need for voltage gain, and no SE-BAL conversion needed, then simple is better – volume control at input and high gm JFET buffer loaded at source with matched JFET (DC coupled) to drive power amp input and interconnect cables.
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Old 16th May 2012, 02:31 PM   #3
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I have one SE 2A3 tube amp with an input sensitivity of about 4v p-p to clip that would benefit from a slight amount of voltage gain but, this was not my primary purpose for this preamp...i am building a pair of NAP140 clone monoblocks and I wanted a preamp to run them that worked from SLA batteriies (just wanted to try a preamp with SLA power source).

So, not absolutely necessary but if one with a minimal amount of gain were available, that would be beneficial....
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Old 16th May 2012, 04:29 PM   #4
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The B1 draws an average current equal to the Idss of the jFETs selected. This could be as low as 6mA (for two channels) but more likely to be in the range 12mA to 18mA (for stereo).
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Old 16th May 2012, 05:10 PM   #5
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Quote:
Originally Posted by AndrewT View Post
The B1 draws an average current equal to the Idss of the jFETs selected. This could be as low as 6mA (for two channels) but more likely to be in the range 12mA to 18mA (for stereo).
So, will it run on 12v +/- rails?
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Old 16th May 2012, 06:04 PM   #6
tinitus is offline tinitus  Europe
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hmm, maybe lazy cat's SSA balanced input/phase splitter with double pair BC550C/560C
I think it runs optimal at +/-15V, and 12V might be fine too, but not sure
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Old 18th May 2012, 02:17 AM   #7
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Default Discrete high performance linestage design with 12v rails

jmillerdoc,

Here is a very high performance balanced input linestage designed for a bipolar 12 volt supply. Low distortion - 0.000082% THD. Can be used single ended too, just tie either input to common. Output will remain the same regardless balanced or single ended.

I provided an LTSpice file of it if you are so inclined.

Enjoy...

Best Regards,

Rich
Attached Images
File Type: jpg BALANCED INPUT 12V BIPOLAR SUPPLY.jpg (72.5 KB, 283 views)
Attached Files
File Type: asc BALANCED INPUT 12V BIPOLAR SUPPLY.asc (6.0 KB, 23 views)
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Old 18th May 2012, 03:17 AM   #8
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Awesome...i am not too familiar with this type of schematic. Can you help me with a few small details? The input seems to be on the left side...what is that circle with the +/- inside it? Also, how os the output wired? One side of the "load" resistor is output and the other groind? Can you please explain it a little better for me? I dont know how to convert this into a wiring diagram....
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Old 18th May 2012, 03:19 AM   #9
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Also, does this require any close matching of devices?
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Old 18th May 2012, 11:41 AM   #10
AndrewT is offline AndrewT  Scotland
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The post7 sch is bal to unbal.

You can convert it to bal to bal by duplicating Q7&8 and feeding them from the two unused collector resistors R9&11
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