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SONY MA900 resistor Mod

post #1 of 12
Thread Starter 

   Hi guys, Long time lurker, I bought a sony ma900 a few weeks ago looking for the most comfortable open design (My ears get hot really easy), tried the HD650 but didn't like the build quality and the comfort at all, So I got the MA900, at first it sounded so thin and "weak", like an AM radio.

I EQ 'ed and it got better but still something was "missing", Until I found out about the "compensating resistors" network, WHAT A DIFFERENCE, I took both resistors out, CLARITY, bass is tight, Treble sparkle, etc..Is like the resistors were degrading the signal somehow. Anyone who needs instructions pls ask, I could take some pics too. Anyone who made this mod too please reply to confirm my findings.  I still dont know what SONY ppl are thinking, at least they should put a switch on the compensating network, not everyone has crappy 60 Ohms OI headphone amps.

post #2 of 12

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Edited by AnAnalogSpirit - 2/27/14 at 12:31pm
post #3 of 12
I want to do this but would like more instructions. How do you open them up?
post #4 of 12
I have a ma900 and am interested in performing the resistor mod. Any diy instructions and photos? Any reviews on modded ma900?
post #5 of 12

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Edited by AnAnalogSpirit - 2/27/14 at 12:11pm
post #6 of 12

Sorry, a bit late, but do you think you could share the pictures of the mods because I am interested, but i am not sure if I can do it since I am kind of new to this.

post #7 of 12
Quote:
Originally Posted by d0od View Post
 

Sorry, a bit late, but do you think you could share the pictures of the mods because I am interested, but i am not sure if I can do it since I am kind of new to this.

 

+1

 

Can someone share a tutorial for M900 resistor mod?

post #8 of 12

And what's the new value of impedance?

 

EDIT: probably it's 8 ohm, found some data on reddit.


Edited by trubul - 3/27/15 at 2:20pm
post #9 of 12

Hello,  I wanted to do the resister mod for my MA900 but couldn't find any instructions.  I'm sick today, couldn't sleep all night so here's my take on the mod.

 

 

Remove pads to access the five small phillip head screws.  Eventhough this is a single entry cable, you will need to open both sides.

 

 

Remove the bezel or ring holding the driver (Thing in background).  The driver is suspended by the grill with just one tab and peg.  Top of picture.

 

 

The grill wraps around the back of the driver.  Remove the grill just like removing the pads.

 

 

Untouched circuit board of the left driver.

Left board after mod.  The two ground wires are unsoldered, put together and soldered to the right pad of the 1RO resistor. Pad closes to the white square blob of epoxy.

The 22O resistor is removed.  It it is easier to leave the 22O resistor and cut the trace on either side of the resistor with a exacto type knife.  Cutting any side will work. The traces are very thin but make sure it is completely cut.

 

 

Untouched right side board.

Same as left side.  Remove ground wire and resolder to the inside solder pad of the 1RO resistor.  The pad closes to the white square blob of epoxy.

Remove 22O resistor or just cut one of the traces.

 

 

That"s it.  Just reassemble and enjoy.

post #10 of 12

nice... any update on sound signature after the mod ?

post #11 of 12

What does this do to the SQ??

post #12 of 12

I've read about better treble and bass but I don't hear that.  Same tones and frequency response but just smoother, natural and organic sounding.  Also the treble, mid and bass crossover is very good.  Like listening to a speaker with a very good crossover network or a full range speaker  with no crossover like a Fostex or Lowther.  This is on a Gustard H10 headphone amp.

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