Re: Re: Notes on Schems...update on grounding experiment

Could you do a little VU meter test, with mix output if you have changed 
the opamp for it(The same opamp is for headphones) or single if not, 
without a noise gate or anything else at minimum volume? I'd like to 
know how many dBs is it now.(I sat my SBLive VOL adj. at -90dB on the VU 
meter(Software) without anything plugged in the Live, then plugged the 
K5 in the Line In and i got a -47dB.

nelsonj_sce-/[email protected] a écrit:

>
> Hack update:
> Since my last note I replaced the other two op-amps with socketed Burr
> Brown OPA4228.  Replacing these two other op-amps did reduce noise
> levels noticeably.  There is still some noise but with 1)the these
> four super clean op-amps, 2)using Multi, 3)routing everything to a
> sinlge output on the multi rather than mix, and 4)using my noise gate,
> noise is really not an issue any more.  I would love to try and
> replace the VCAs also, but I have not been able to track down a spec
> sheet (or any other info on the) on them so I do not have a clue as
> what might works as an upgraded part.
>
> If anyone can help, the VCAs are part M5222L and they are from
> the same off-brand Japanese JRC company that is used elsewhere in the
> K5.  If anyone can help me with details on the M5222Ls I will see if I
> can find a replacement parts.
>
> My bottom line: If you are willing to lay-out $30 for the four BB
> OPA4228 and sockets, and you if you are willing to remove some
> tough-to-remove parts, I highly recommend this op-amp replacement
> hack.  My K5 has much less noise and just sounds much warmer/classier
> with the new parts.  I would love remove more noise, but right now it
> sounds very good and I am not very motivate to continue hacking.  (I
> do still plan on replacing the headphone circuit though since I
> already made the new circuit and all I have to do is wire it up.)
>
> An interesting aside:  After I did the latest op-amp replacement,
> everything sounded great in multi, but when I went to single I had
> serious problems.  Various ranges of the keyboard worked fine, while
> other ranges sounds like a fried amp circuit.  It turns out that while
> I was removing IC8 I accidentally pulled part of the circuit board
> trace off that connected pins 1 and 2 on IC8.  This trace provides the
> feedback loop between the (-) and output of line G2.  Once I tracked
> down the problem I was able to reconnect pins 1 and 2 and then
> everything in single mode worked great.  What I conclude from this is
> that the K5 in single mode is splitting different ranges of the
> keyboard to different op-amps.  I am not sure what K% is doing in
> multi but multi (ouput 1) DOES NOT use the opamp in IC8 pins 1-2-3. 
>
> Hack on.     
>     


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