Saturday, July 31, 2010

Altec Lansing MX5021 Modification (Part 2)

Change the op-amp, in order to change its sound characteristic and lower SNR.
OPA2111KP and OPA2107AP.

Tried LM4562, LME49720HA, LME49720NA, OPA2107AP, OPA2111KP, OPA2132PA, OPA2277PA, LT1364, LT1352, LT1057 and....
End up using OPA2111KP because it sounds more natural.


Top View Diagram(single opamp)
Just bend its leg to DIP-8 according to the number then fit into DIP-8 socket.

Finally got the decent capacitor for audio. Nichicon Fine Gold.

Another re-cap plan(same as the part 1, just going to change better capacitor).

Finally replaced with better quality audio grade capacitor and op-amp with semi-gold plated 8DIP socket.
Nichicon Fine Gold series and Nichicon BP(Bi-polar).
Texas Instruments OPA2111KP.

C36 decoupling capacitor for ALL of the Op-Amps and IC.
Replace with 100uF to 470uF.(the higher the better)
Add(optional) 0.1uF MKP across the capacitor at the bottom of PCB for better performance.

Four C2/C7/C99/C100 green decoupling capacitor for both chip amplifiers.
Replace with 0.1uF MKP or MKT capacitor.(note the spacing of lead)

C9 feedback capacitor of subwoofer's chip amplifier.
Replace with good capacitor eg. Nichicon Fine Gold. 47uF will do.

Smoother sound overall.

<- Previous...Next ->


  1. Do you have cheaper alternative Op-amps that you recommend for the MX5021 2.1 Speakers?
    The ones you used were OPA2107AP(Position U5),OPA2277P(U6 and U12),OPA5444KP(Position U7 and U9).
    If you could recommend alternatives for each that would be great. I believe Jimmy Auw used Burr Brown OPA2134PA for Position U7 and U9.


  2. It would be better to have them all the same.

    My recommendations are NE5532 < LM4562(cons:hot operating temperature) < OPA2111KP. Any beyond these are useless due to the limitation of power amplifier chip.

    For me, I would change the C54, C61, C118 and both 4700uF capacitors first. =]

  3. 11-4-2014 Does anyone have these boards for sale? Mine went out. I can solder, but not sure how to troubleshoot.

  4. I'm looking for the part number and name of the part on the board "U10"

  5. Whats the part number for "U10" on the board?

    1. Hi, Philippe. It should be a 7809 Power Regulator.