I tried the ebay MX50 DIY Kit, Class AB 100W+100W; Worked but problem. - Page 5 - diyAudio
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Old 23rd September 2011, 02:48 AM   #41
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Welcome to the forum, ljm.

I think I looked at the pinouts of a 2n5551, but posted a link to the correct cc5551 datasheet. It shows a different pinout, and that would make q2 & q4 a current mirror.

Sorry, my bad.
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Old 23rd September 2011, 05:33 AM   #42
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by Buckeye View Post
Welcome to the forum, ljm.

I think I looked at the pinouts of a 2n5551, but posted a link to the correct cc5551 datasheet. It shows a different pinout, and that would make q2 & q4 a current mirror.

Sorry, my bad.
This is not your mistakes, because the transistor is rare.
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Old 23rd September 2011, 01:05 PM   #43
sbrads is offline sbrads  United Kingdom
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Quote:
Originally Posted by ljm_ljm View Post
This is not your mistakes, because the transistor is rare.
It's nice to have the designer's input, thank you.

Which is the best sounding amplifier, the MX50 or the MX50X2? I bought the MX50X2 because of its 4 output devices.
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Old 23rd September 2011, 01:22 PM   #44
ljm_ljm is offline ljm_ljm  China
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Originally Posted by sbrads View Post
It's nice to have the designer's input, thank you.

Which is the best sounding amplifier, the MX50 or the MX50X2? I bought the MX50X2 because of its 4 output devices.
MX50X2 originated in MUSICAL FIDLITY MF-XA50. Is a very distinctive, good circuit.

MX50 circuit similar, but output using low distortion CFP circuit.

The two are very stable, and very convenient production.
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Old 11th October 2011, 09:39 AM   #45
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Default MX50X2

Hi ljm, I've just built the MX50X2 and it sounds very good. Just wondering if it's possible to reduce the gain of this amp, the rest of my kit has to have the gain turned right down when driving it to produce reasonable listening levels.

Thanks
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Old 11th October 2011, 01:59 PM   #46
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Originally Posted by jamesjbrookes View Post
Just wondering if it's possible to reduce the gain of this amp, the rest of my kit has to have the gain turned right down when driving it to produce reasonable listening levels.

Thanks
Change the value of R7 (as in the post 39 schematic) to 27k. If it's still too loud, up the value of R9 to 1k2 or 1k5 or 1k8 or whatever works for you.

Last edited by ingenieus; 11th October 2011 at 02:01 PM.
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Old 12th October 2011, 02:06 PM   #47
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Originally Posted by ingenieus View Post
Change the value of R7 (as in the post 39 schematic) to 27k. If it's still too loud, up the value of R9 to 1k2 or 1k5 or 1k8 or whatever works for you.
Thank you ingenieus, I'll try your suggestions as soon as time permits.
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Old 24th May 2012, 06:25 PM   #48
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Hello. I am very bad speak english, i am from Russia. bought the same kit. one channel is working fine, and when you turn on the second channel, the quiescent current in the arm + shows 0.82 A and is not regulated. may suggest what could be the problem. Thanks in advance.
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Old 26th May 2012, 07:06 AM   #49
sbrads is offline sbrads  United Kingdom
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Originally Posted by 35house View Post
Hello. I am very bad speak english, i am from Russia. bought the same kit. one channel is working fine, and when you turn on the second channel, the quiescent current in the arm + shows 0.82 A and is not regulated. may suggest what could be the problem. Thanks in advance.
Have you adjusted the bias potentiometer? If you have tried already and there was no effect on the current, check the pot resistance varies on a DVM.
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Old 8th November 2012, 10:35 AM   #50
xslavic is offline xslavic  Moldova
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i think the problem is only the preamplifier and the 5401 and 555thing stage
if i would have(d) time i would replace them with some higher waTage transistors
and of course again the calculations
Rihanna - Te Amo - YouTube
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