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Old 30th July 2008, 03:24 AM   #1
lineup is offline lineup  Sweden
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Smile Symphony No. 1 MOSFET Amplifier

Anybody tried build this amplifier.
Symphony No. 1 MOSFET Amplifier by www.bearlabs.com
Looks like it uses Lateral MOS.
But I am not sure.

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Click the image to open in full size.
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Old 30th July 2008, 11:43 AM   #2
AMV8 is offline AMV8  United Kingdom
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Lineup

Great find.

I am interested to see that there are no source resistors on the output devices even though each channel uses 6 parallel mosfets on each rail. This is claimed to be possible due to super matching of the output devices. I wonder what the bias current is.

Does anyone have any knowledge of the circuit?

Has anyone heard one?

Don
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Old 30th July 2008, 12:35 PM   #3
lineup is offline lineup  Sweden
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Quote:
Originally posted by AMV8
Lineup
Great find.
I am interested to see that there are no source resistors on the output devices even though each channel uses 6 parallel mosfets on each rail. This is claimed to be possible due to super matching of the output devices. I wonder what the bias current is.
Does anyone have any knowledge of the circuit?
Has anyone heard one?

Don
Don.
I found this amplifier is from 2004 something.
There is an old topic about it.
In some posts bear describes his amplifier.
http://www.diyaudio.com/forums/membe...fo&userid=1912
http://www.diyaudio.com/forums/showt...153#post497153
Also here is some data:
http://www.bearlabsusa.com/NEXT/SYMPHONY.html

Some details.
Real high quality components & powerful setup!
Down the center are the filter capacitors.
This bank of caps has a total capacitance of over 500,000 ufd.!!


The MOSFETs are HITACHI old Laterals, 2SK176 / 2SJ56
So I guess the idle bias is 100-150 mA per output pair.
Click the image to open in full size.
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File Type: jpg symphony_2sk176.jpg (62.1 KB, 503 views)
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Old 30th July 2008, 01:24 PM   #4
AMV8 is offline AMV8  United Kingdom
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lineup

Thanks for your reply.

I wondered if the amplifier used the old Hitachi mosfets. I still have a number of those. I still think they sound like one of the best output devices. Although more recently I have been bying the IRF240/IRFP240.

I also find bears comments on the size of the power supply required interesting. He finds as I have, that a larger power supply does provide more clarity on complex music passages, especially if a large dynamic range is associated with that passage.

Thanks again lineup.

Don
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Old 30th July 2008, 04:55 PM   #5
lineup is offline lineup  Sweden
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Hello AMV8

Yes, those old HITACHIs are among the best power transistors in this world.
Why I say this?
Because I really love those.
Not that I have ever used them, myself.
They are not so easy to find ......


The Toshiba 2SK1056-57 2SK1058 are good + 2SJ62
But those HITACHI SK176 2SJ56 is maybe even better .. eventhough not as powerful.

You can find datasheets here, if you have not already:
2SK175 2SK176
http://www.datasheetarchive.com/preview/3938137.html
2SJ55 2SJ56
http://www.datasheetarchive.com/preview/3937787.html
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Old 31st July 2008, 02:07 AM   #6
Leolabs is offline Leolabs  Malaysia
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Nice copper bar.
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Old 31st July 2008, 03:24 AM   #7
lineup is offline lineup  Sweden
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yes i noticed, too
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Old 10th August 2008, 04:16 AM   #8
lineup is offline lineup  Sweden
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Any news about this amplifier.
Maybe bear of bearlabs can tell something?
http://www.bearlabsusa.com/

Here we can see one Copper Bar as mentioned earlier.
Instead of using wire for currents!

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