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wordclock distribution/preamp noise
Old 4th February 2009
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audiothings's Avatar
๐ŸŽง 15 years
wordclock distribution/preamp noise

I had posted this question in what was probably not the most suitable forum... sorry if you've already seen it:

At the concert hall where i often man the Yamaha Ls-9, we have the Ls-9 "head amps" and Presonus Digimax FS preamps. On comparison, we found the Presonus units to be significantly noisier than the built in preamps... They are still usable but we keep them for louder instruments requiring less gain.

The Presonus units (x4) are coming into the console over ADAT. The systems integration guy has taken the wordclock output from the Ls9 and split it into 4, using an active video splitter and sent the four outputs to the Presonus wordclock inputs... (tried to convince him that there was probably going to be some tradeoff but he was sure that it would be no problem).

I don't believe that the Presonus can be so much noisier than the yamaha head amps... (Tho', like I said, they have no problems with noise when not being driven hard). Could it be because of the clocking/distribution?

Old 6th February 2009
Lives for gear
๐ŸŽง 15 years
Hi AT - Isolate one Presonus from the others and crank the gain up. Feed a Presonus preamp channel a tone in it's current clocking/routing configuration, and bring an "optical" output up on a fader. Bring the same presonus analog output up on another fader and match the levels. Bring the same tone up through a Yamaha preamp and match all three levels. Now, turn off the tone. Compare the noise. Remove the clock input from the presonus. Does the noise change? While not a truly scientific method, this should let you know if you've got noisy preamps or a clock problem. Or, if the Presonus can simply deliver more gain than the Yamaha...
Do you mean to say that you have an unnecessary ADAT machine in your signal flow, or that you're using light pipes to connect the preamps to your console?
Cheers! JR
Old 10th February 2009 | Show parent
Lives for gear
audiothings's Avatar
๐ŸŽง 15 years
thank you for your reply ripple fx. Guess there is no option but to crawl behind the racks and get my knees dirty, doing some testing. If there is a clear technical reason why the current setup is bound to be noisy, I can save myself the trouble.

Do you mean to say that you have an unnecessary ADAT machine in your signal flow
of course not! there is no ADAT machine! I meant ADAT protocol
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