2. amps-preamps
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Anyone tried changing OPAMPS in Music Hall A25.2?

I have just chnaged the OPAMPS in my Music Hall A25.2 from the stock Burr-Brown OPA134 for some Burr-Brown OPA2107 units and holy shit there is difference in the sound. It is very noticable and very much better! The deliniation of instruments great, bass drive is far better, smoother treble and no more of that goofy midrange weirdness. I run Modified Klipsch Chorus II's and the bottom end just came to life. I am really suprised at the results! The opamps were $30 for the pair from digikey, they rip you hard core on shipping though $10 for like shipping a 3x5 inch box of air. (oh well) They did come pretty quickly.
jffyg
6 responses Add your response
elevick
2,636 posts
 
Same results in my MH trio. Amazingly responsive to mods. My latest mod was removing the ribbon cables inside and hard wiring the points. Just as big as a change.
magfan
1,583 posts
 
I made a headphone amp using OPA 2132s. Similar but more stable version of the OPA 2134, apparently. this is the stereo version of your OPA 134, I think.

Are your opamps socketed? Easy to do 'opamp' rolling at that point, since they all have same pinouts from the half-dozen I've looked into.
mechans
3,048 posts
 
Evidently the Australian Burson company of DAC fame makes modified Op amps are the rollable into MH. These are expensive but are reported to be incredible.
jffyg OP
53 posts
 
Sorry have to make a correction the original opamps were OPA2134 not OPA134 as I stated above and they are duals. I guess some op amps are singles like the OPA627 and OPA637. If you need to use these you have to have what I believe are called daughter boards which allow you to mount two of those chips on a circuit board which then plugs into the 8 pin socket. (yes thankfully the MH has sockets) I am thinking of changing out the op amp in my Creek OBH-11 but it is not socketed so I would have to de-solder and install a socket. Sounds dangerious with my skills ;^)
magfan
1,583 posts
 
Can't recommend you install a socket unless you have both the skillset and the right stuff. Solder sucker? Solder wick? Real low power iron? Adjustable? Good, hi-end socket?

'Modified' opamp? How so? Unless manufactured from a new set of masks and with modified implant and diffusion parameters? That would make it a 'new' part. It's not like you can open 'er up and just change transistor thresholds and resistor values.

The OPA2132 / 2134 are considered pretty musical.
Try from this list....All have been used in the CMOY headphone amp with various degrees of success.

http://tangentsoft.net/audio/opamps.html
hemihead05
16 posts
 
Does anyone have any input on the four 604ap in the player ? Are they they the outputs or buffer stage?

Mine has four of those and 2opa2134.

whats the best choice for all 6?
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