LJM MX50 kit amp

homemodder

Disabled Account
2006-05-12 5:36 am
Please help us and someone could clarify the differences between the various versions of the LJM MX50 amp kit - we've seen for sale versions 6.1 and 6.3. More recently the SE version. Does the transistors 5401, 5551, 1815 and with 2SB649 & 2SD669 plus power Sanken 2SA1186 and 2SC2837 as an amplifier providing good fidelity music reproduction?

That depends on the circuit design and transistors used, for starters the 2sb649/669 hasnt been manufactured for many years so will probably be either fakes or second source which implies they wont be as good. As for the others they are good parts if not fakes.
 
For study purposes, and to express opinion, publishing the scheme available in electronics stores Ebay. Warning do not encourage copying and be respectful of intellectual property of the device.
 

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theb0b

Member
2012-06-11 12:33 pm
This schematic is distributed in stores Ebay, as usual, the amplifier must be for sale.

I did the assembly and operating two units MX50-SE with output Sanken A1186 and C2343. The result was surprising, tested on multi amplification, mid and treble bands. The voice is very natural and treble, like breaking glass, percussion dishes are outstanding. I can say that is very close to my F5 running.

A small mod is change the cap MKP of 3.3 uF the input circuit was replaced by Nichicon BP-S of 2.2 uF. Very good indeed, considering the price of the kit.

Sorry for my bad English.
 

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theb0b

Member
2012-06-11 12:33 pm
Thanks for your report augustoriodosul. I've bought 2 of these kits for US17$ each from ebay and I am intending to use them to repair an old Sony amp with burnt out power amp section.

Building an amp like this, the largest cost is the power supply and the case/heatsink and hardware.

Reusing old junk amps is a cost effective way for a beginner to build a nice sounding system.

What rail voltage did you use? Do you think this kit can really take 50+/-?
 
What rail voltage did you use? Do you think this kit can really take 50+/ -?

I use a multi amplified with 6 way. Then mid and treble amplifiers are low power as class A. My MX50-SE run with 36 VDC power which would give an approximate 50 to 60W. Do not heat up, just get warm.

Do not forget that transistors output are important, had read good reviews about Sanken 2SA1186 and 2SC2837 with fT 60 and 70 MHz, are very good and fast. Other little mod, change MKP input for Nichicon BP-S 2,2 uF, also increase quality.
 

baskiria

Member
2006-01-20 8:49 pm
HU
I bought this kit on ebay, and built it. The components look genuine to me, no fake parts. Output is 2SB817 and 2SD1047 from KEC. LJM did a really outstanding work here, the amp sounds amazingly good. No turn on noise, no turn off noise, very quiet, only a very minor hiss. The imaging is very good, both stereo and image deepness is outstanding compared to what amps I heard. Dynamics is also great, what has to be quiet is quiet, and it do really have the thump when it's needed. It also sounds very clean.

This is a recommended project to build.
 
I bought this kit on ebay, and built it. The components look genuine to me, no fake parts. Output is 2SB817 and 2SD1047 from KEC. LJM did a really outstanding work here, the amp sounds amazingly good. No turn on noise, no turn off noise, very quiet, only a very minor hiss. The imaging is very good, both stereo and image deepness is outstanding compared to what amps I heard. Dynamics is also great, what has to be quiet is quiet, and it do really have the thump when it's needed. It also sounds very clean.

This is a recommended project to build.

I agree with your opinion and recommend using the Sanken 2SA1186 and 2SC2837 transistors with fT 60 and 70 MHz. An excellent amplifier with low cost.
 

maxilogic

Member
2007-08-25 10:41 pm
Because they are very fast, his response to transients is better. I bought the Sanken separate but tried the Sanyo - it seems that the response at high frequencies of Sanken is also softer, but obviously this is subjective. You can verify the quality of these Sanken in threads diyaudio.com

For MX50-SE, do I need to change other components if I want to try the Sanken 2SA1186 / 2SC2837 or just simply substitute the KEC KTB817/1047 with the 1186/2837. Thanks.