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Old 22nd June 2012, 01:07 PM   #671
AndrewT is offline AndrewT  Scotland
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Not very well.
Probably badly.
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regards Andrew T.
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Old 22nd June 2012, 01:27 PM   #672
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Not very well.
Probably badly.
Why well not?!
A higher "quiescent current" (about 100mA), audio amplifier goes to the class-AB!
Class-AB less THD distortion, ....
Andrew cheers!

Last edited by formula 22; 22nd June 2012 at 01:34 PM.
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Old 22nd June 2012, 06:37 PM   #673
AndrewT is offline AndrewT  Scotland
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No Tempco
ClassB ish
Odd feedback
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Old 25th July 2012, 09:02 AM   #674
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hi Apex sir,
Currently using this amp with 5 pairs of 2n3773,supply 40-0-40 AC 1.5kv traffo,20,000mfd caps per side on 4 ohm load. sounds good to my ears even as full range amp but currently coupled with your 2x12 inch subwoofer enclosure in a three way system.
What output power i should expect from this ?
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Old 25th July 2012, 10:13 AM   #675
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Originally Posted by sudhir kumar View Post
hi Apex sir,
Currently using this amp with 5 pairs of 2n3773,supply 40-0-40 AC 1.5kv traffo,20,000mfd caps per side on 4 ohm load. sounds good to my ears even as full range amp but currently coupled with your 2x12 inch subwoofer enclosure in a three way system.
What output power i should expect from this ?
250W on 4 ohm load with 40-0-40 AC, can you post pictures of your sub?
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Old 7th August 2012, 11:28 AM   #676
olafk is offline olafk  Germany
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Default Very hot

Hi,

I built the amplifier (picture see post #663) with two pairs of 2N3773 and I use +-60V DC. Now the Transistors MJE350/340 become to hot. I can touch them for only 3-4 seconds and I think it is a bit critical.
Should I reduce the voltage (have regulated power supply) or are there any other things I can do? I changed the heatsink to a bigger version for TO220 like the MJE15030, but gave no better result.
Can anybody help me?

regards
Olaf
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Old 7th August 2012, 12:56 PM   #677
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Originally Posted by olafk View Post
Hi,

I built the amplifier (picture see post #663) with two pairs of 2N3773 and I use +-60V DC. Now the Transistors MJE350/340 become to hot. I can touch them for only 3-4 seconds and I think it is a bit critical.
Should I reduce the voltage (have regulated power supply) or are there any other things I can do? I changed the heatsink to a bigger version for TO220 like the MJE15030, but gave no better result.
Can anybody help me?

regards
Olaf
Nice work, MJE340/350 work in class A and must be hot but use 100R resistor instead 56R around MJE340 and this will reduce current in VAS CCS and disipation on MJE340/350 also.
Can you share your pcb?
Regards

Last edited by apexaudio; 7th August 2012 at 01:09 PM.
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Old 7th August 2012, 01:01 PM   #678
olafk is offline olafk  Germany
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Default Hot

Hi Apex,

thanks for the advice. I will test it after work this evening.

regards
Olaf
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Old 7th August 2012, 07:17 PM   #679
olafk is offline olafk  Germany
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Default PCB

Hi Apex,

it works. Thankyou.
Here is PCB.

regards
Olaf
Attached Files
File Type: pdf Quasi Amplifier for beginners.pdf (27.4 KB, 419 views)
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Old 7th August 2012, 07:21 PM   #680
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Originally Posted by olafk View Post
Hi Apex,

it works. Thankyou.
Here is PCB.

regards
Olaf
Nice PCB, thank you.
Regards
Attached Images
File Type: jpg qusi by olaf.JPG (103.6 KB, 633 views)

Last edited by apexaudio; 7th August 2012 at 07:37 PM.
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