I tried the ebay MX50 DIY Kit, Class AB 100W+100W; Worked but problem. - Page 6 - diyAudio
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Old 23rd January 2013, 04:13 PM   #51
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Default MX50 100W + 100W

I built the same amp - however the modules I bought off Ebay were pre built and tested.

I'm not sure if the circuit diagram I posted is correct for the modules I have - but it was the one published on the auction page.

Details here is anyone is interested.

Mine is running at a lower power, as I'm using a 35-0-35 Vdc supply.
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Old 25th January 2013, 03:05 PM   #52
sbrads is offline sbrads  United Kingdom
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Quote:
Originally Posted by audio_tony View Post
I built the same amp - however the modules I bought off Ebay were pre built and tested.

I'm not sure if the circuit diagram I posted is correct for the modules I have - but it was the one published on the auction page.

Details here is anyone is interested.

Mine is running at a lower power, as I'm using a 35-0-35 Vdc supply.
Any verdict on sound quality yet?
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Old 25th January 2013, 05:13 PM   #53
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Originally Posted by sbrads View Post
Any verdict on sound quality yet?
It sounds absolutely superb.

I currently have access to several power amps, Harman Kardon HK870, NAD2200 (very modified),Rotel 850 - and it beats them all, hands down.

It's very detailed, and the bass is simply superb too.

Source is Marantz CD17 (modified), Cambridge Azure DAC Magic, Ebay "Big DAC", and Logitech Squeezebox Duet.
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Old 1st April 2013, 07:18 PM   #54
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Default Decrease gain

Quote:
Originally Posted by ljm_ljm View Post
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.
About MX50-SE(v7), I have a question, please:

I want to decrease the gain to 20 ~ 25 times for use in multi amplification for treble and mid range. What are the values ​​and the resistors need to change?

thank you
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Old 4th September 2013, 06:34 AM   #55
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On MX50-SE you can see the 330 Ohm above the 2 pcs of 100 Ohm and the 10K Ohm next to 330 Ohm. Current gain is 31 times. If you want change gain to 20~25 times, you can change the 330 Ohm to 470 Ohm then the gain changed to 22 times.
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Old 4th November 2013, 06:58 PM   #56
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you tell me how to set up their amps? the picture you need using the variable resistor to set the voltage 550mV? I did that but little bass in the sound has to turn the equalizer in the player. Transistors may not work properly? on hearing the sound of a very high quality, but a little bass.Nutrition 47 - 0 - 47.

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Old 4th November 2013, 06:59 PM   #57
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Click the image to open in full size.

you tell me how to set up their amps? the picture you need using the variable resistor to set the voltage 550mV? I did that but little bass in the sound has to turn the equalizer in the player. Transistors may not work properly? on hearing the sound of a very high quality, but a little bass. Nutrition 47 - 0 - 47
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Old 12th March 2014, 07:20 AM   #58
ljm_ljm is offline ljm_ljm  China
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I have to update the data.
Attached Images
File Type: jpg IMG_3480.jpg (246.0 KB, 189 views)
File Type: jpg IMG_3481.jpg (408.3 KB, 186 views)
File Type: jpg IMG_3482.jpg (498.1 KB, 180 views)

Last edited by ljm_ljm; 12th March 2014 at 07:22 AM.
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Old 16th July 2014, 01:31 PM   #59
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Originally Posted by Buckeye View Post

Moral of the story... don't underestimate the need for on-board filter and bypass capacitors on the rails.
If you look at the original Musical Fidelity pcb that LJM posted you can see that PSU is only an inch or two away from the output transistors. With PSU so close one may not need bypass caps for absolutely stable performance. But LJM made clone board without PSU and many constructors will place PSU at greater distance from the amp board so it would be highly desirable to have bypass caps onboard near output transistors. It would probably be the easiest to place footprint for 100nF/100V SMD polyester caps on the bottom side of pcb near output transistors, if LJM decide to make some new version of the pcb.
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Old 16th July 2014, 02:19 PM   #60
AndrewT is online now AndrewT  Scotland
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Originally Posted by ivanlukic View Post
................. PSU is only an inch or two away from the output transistors. With PSU so close one may not need bypass caps for absolutely stable performance.................
One certainly does need local decoupling at a distance of an inch or so.

That inch or so implies a minimum flow and return circuit length of >50.8mm
That is enormous.
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