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Building from a pair of MA-9S2 boards, first project
Building from a pair of MA-9S2 boards, first project
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Old 8th November 2020, 05:17 PM   #21
sajti is offline sajti  Hungary
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Join Date: Apr 2003
Location: Százhalombatta, Hungary
You are correct. You may have to increase the 220p, to 330pF.
The 2200/240 feedback gives something like 20dB gain. 2200/1100 will provide 3x gain, which is 9.55dB.
I build my version too, based on Marantz Reference series. However it is more sophisticated than the Chinese version.
Sajti
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Old 8th November 2020, 06:55 PM   #22
kozard is offline kozard
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Join Date: Mar 2012
Quote:
Originally Posted by sajti View Post
You are correct. You may have to increase the 220p, to 330pF.
The 2200/240 feedback gives something like 20dB gain. 2200/1100 will provide 3x gain, which is 9.55dB.
I build my version too, based on Marantz Reference series. However it is more sophisticated than the Chinese version.
Sajti

Are there schematics and PCB (or files) available for your more sophisticated version?
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Old 8th November 2020, 07:30 PM   #23
sajti is offline sajti  Hungary
diyAudio Member
 
Join Date: Apr 2003
Location: Százhalombatta, Hungary
Hi,
yes it has. Pcb manufacturer friendly, as the size is 100x90mm, and it includes the output relay too.
Sajti
Attached Images
File Type: png sch.png (41.5 KB, 80 views)
File Type: png pcb.png (181.0 KB, 82 views)
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Old 8th November 2020, 07:49 PM   #24
kozard is offline kozard
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Join Date: Mar 2012
Quote:
Originally Posted by sajti View Post
Hi,
yes it has. Pcb manufacturer friendly, as the size is 100x90mm, and it includes the output relay too.
Sajti
Nice. Any chance we could we get the gerbers to order boards? Did you use Eagle, KiCad or another tool?

Does connector 1 go to an external control board for the relay? Is the temperature switch something like a bimetallic temperature switch?
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Old 8th November 2020, 07:56 PM   #25
sajti is offline sajti  Hungary
diyAudio Member
 
Join Date: Apr 2003
Location: Százhalombatta, Hungary
Hi,
gerber is available too.
Yes, CON1 goes towards the protection controll board. It contains, the turn on delay, the DC protection, and the inrush current limiter for the mains transformer(s).
Temperature switch is for bimetallic temperature limiter. I use Airpax 67L070 mounted on the board.
Sajti
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Old 30th November 2020, 12:16 AM   #26
kozard is offline kozard
diyAudio Member
 
Join Date: Mar 2012
Quote:
Originally Posted by sajti View Post
Hi,
yes it has. Pcb manufacturer friendly, as the size is 100x90mm, and it includes the output relay too.
Sajti

The boards just arrived!

What do you think of 2SC6145 & 2SA2223 instead of 2SC3519 & 2SA1386? I ask since I already have them from my earlier DIY MA9S2 and other projects.

Since the TTC004 bias transistor is at 90 degrees to the outputs I assume it is not attached to the heatsink? Or is the TTC004 attached to the heatsink?
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