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Burl B2 Bomber Clocks Synchronisers/Clock Generators
Old 11th October 2014
  #1
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Burl B2 Bomber Clocks

Can anybody tell me how Burl processes external clock signals? (B2 Bomber DAC)

Is the clock in terminated?

Does it have clock-recovery built in?

Is it OK to use Clock IN and then provide a Clock OUT to a second Burl DAC?

Thanks for any help you can provide.

Last edited by dseipel; 18th October 2014 at 04:25 PM.. Reason: Remove ADC
Old 25th October 2014
  #2
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Answer

For inquiring minds that want to know...

The Burl B2 Bomber DAC uses a fast, low self jitter PLL.
Old 25th October 2014
  #3
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Quote:
Originally Posted by dseipel View Post
For inquiring minds that want to know...

The Burl B2 Bomber DAC uses a fast, low self jitter PLL.
Normally a PLL has a few specs,

a) Intrinsic (self) jitter
b) Jitter rejection corner frequency, that is the frequency the PLL starts
rejecting at, say 10Hz or less for a very very good one.
c) Jitter rejection slope or amount at say 100Hz.
d) What sort of clock is it, a VCO (voltage controlled oscillator) , VCXO (volt
contr xtal osc) , DDS (direct digital synthesis) other; for example JETPLL
as pateneted by TC electronics.

A fast low self jitter PLL doesn't mean much -
It could mean that the jitter rejection corner freq is pretty high - which is not a
good thing. Maybe they mean fast lock time.

Who knows.

T
Old 25th October 2014
  #4
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Good Stuff!

Thanks for the comment.

When I asked Burl, I had included a section from Grimm Audio's manual for their CC1 clock. My setup has evolved to where I either need to add clock distribution or go to a multichannel converter where the converters are using the same clock. If I add clock distribution, I don't want to degrade the conversion quality of the Burl units. The other factors that you present definitely go beyond my technical knowledge. I'm in the boonies, and as such don't have the luxury of try things out in my system. I'm trying to make an informed choice.

Here is the bit from the CC1 manual that I sent to Burl:

"PLL setting in attached devices.

Audio devices capable of locking to an external clock use a phase-locked loop to do so. Details of this are covered in our white paper “PLL and clock basics” that can be found on the info page of our website. An important thing to know for a CC1 user is that some products have two modes, usually called “fast/wide” or “slow”. The slow setting has the best suppression of incoming jitter, and is the optimum choice when the incoming clock is polluted. The downside of the slow setting is that the jitter in the recovered clock is fully dominated by the clock oscillator that forms part of its PLL. If the incoming clock happens to be much stabler than that, the slow mode will actually end up adding jitter. The latter scenario is almost guaranteed to be the case with the CC1, which is significantly cleaner than any clock oscillator we’ve found in commercially available audio products so far. As a rule, in this case it is usually better to select the “fast” mode. In fast mode, the PLL will track the incoming clock more closely and if the incoming clock is extremely clean, the same will go for the regenerated clock.

Products that have a fixed slow PLL, such as those from Apogee, dCS, Lynx or Prism Sound, will improve comparably little compared to products with a switchable or relatively fast PLL like those from Avid, Lavry Engineering, MOTU, Mytec, SSL or RME. Digital loudspeakers that feature a word clock input, like Dynaudio Air, will also benefit from slaving to the CC1."
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