ADA8000 - What opamps for upgrading?

[piano]

LT1359 PDF schematics.

Since each set of pairs of channels is reversed, I am wondering if the chips were put in backwards perhaps. That is the only thing I can think of here.

EDIT: the LT1359 chips were installed correctly. It looks like all of the chips are bad or not well suited to going in the ADA8000.

EDIT AGAIN: The LT1359 chips were not bad and the installation was great. My apogee Ensemble lightpipe out was quirky - perhaps software or a hardware issue. But it was not the ADA8000 mod.

[piano]

Well,

I have finally gotten around to testing the OUTPUTS of the my experiment with my 'super modded" very custom ADA8000 with Linear Technology op amps.

The LT's sound great SPECTACULAR but the channels are reversed in pairs 1 is 2 and 2 is 1, 3 is 4 and 4 is 3, 5 is 6 and 6 is 5, 7 is 8 and 8 is seven. Also channel 8 is not working.

NOW, BLA was nice enough to do this experiment of mine. SO.... BIG TIME KUDOS to them. They also did it on the condition that it it may NOT work perfectly as it was a bit of an experiment to them as well. BLA did great work.

Also, I understand that LT's quality control is not the greatest - so often, the op amps ordered are duds. I tried to order the fully tested versions but they were out of those. I am not sure of the problem here but I am going to try another set of opamps on the outputs. So replacing the LT1359 quads with another quad.

I am going to try the LME49740 as these were specifically designed for high end audio.

EDIT: It looks like there is some quirkyness with my Apogee Ensemble - which was the problem when sending incorrect channels via light pipe. As such it looks like everything was done correctly and you CAN use the LT1359's and LT1358!

[doulos30]

I recommend the MC33079 in and out it's cheap and the best bang for the buck improvement on the ada8000

[Jidis]

Originally Posted by piano

Also, I understand that LT's quality control is not the greatest - so often, the op amps ordered are duds.

That sounds like loads of fun with a surface mount package!

George

[Jim Williams]

LT's parts are very reliable and are fully tested before sale. Users can easily damage them with excessive heat or overloads. This is not a problem with those parts but rather the installer.

[piano]

Originally Posted by Jim Williams

LT's parts are very reliable and are fully tested before sale. Users can easily damage them with excessive heat or overloads. This is not a problem with those parts but rather the installer.

Hmmm..... well the problem was NOT with my BLA modded ADA8000 but rather with the lightpipe of my Apogee Ensemble. Good to know that LT parts are very reliable.

[piano]

I really love the sound of this mod. However there are problems on playback if left alone.

This applies to ADA8000 units manufactured after late 2009 (units with a date code label reading "0912" or later). In late 2009, the ADA8000 implemented new D/A converters from CIRRUS which offer improved quality compared to the previous D/A converter chipset.
However, the new D/A converter chipset goes into mute after receiving 8192 consecutive samples of digital zero (absolute silence, or "digital black"). The next non-zero sample reactivates the D/A chipset which creates a short waiting period as the D/A chip "wakes up" and the audio output level returns to normal.
Under normal operating conditions this auto-mute never happens. However when used with digital mixing consoles or digital audio workstations (DAWs) with all faders down or in stop mode, this could cause this "mute" or "sleep" behavior.

The offending chip is a CIRRUS LOGIC CS4270-CZZ http://www.cirrus.com/en/pubs/proDat.../CS4270_F1.pdf

There are 4 of these chips on the board. I am not sure what is a suitable replacement. You can, as a workaround send an inaudible signal to keep the unit responding quickly all the time.

[drtechno]

remove the muting transistors. from the mute a and mute b pins 21 and 24.

if the transistors are not there, it wont pull down the output and mute it.


you'll just have to deal with the pops at boot time.