yikes - hope this doesn't apply to Motu's avb series too - I just got a 24
ao and am thinking if a 24 ai....
Post by Richard Lee
There's a number of issues brought up in this thread which Core Sound have
been aware of for some time and have been attempting to address. But its
difficult for a small company to make major changes on the small turnover.
For what its worth, the 'new' PPAc will give around 1dB improvement in
perceived S/N regardless of your favourite weighting (more if you are not
using a Metric Halo or similar). This has been achieved mainly by a bit
more than 1dB more output. 8>D
The MOTU Traveler has near SOTA noise performance but the design is flawed
and they often become very noisy over time. If you have one which has been
OK for more than 12 mths, you are probably OK
I'm on my 3rd Traveler. The 2nd one developed the noise almost exactly 12
mths after I received it. As the 1st took 3 mths to be 'repaired', those
of us in Oz are not happy bunnies. (The Traveler is actually Angelo
Farina's who kindly lent it to Cooktown Recording and Ambisonic
Its pretty obvious MOTU don't have in-house design expertise and they deny
there is a problem. I've not looked inside a MOTU 4pre ... but so far,
those we know of haven't developed this problem so it has our cautious
In terms of noise with TetraMic, I'd expect a 'good' Traveler to be on par
with Sound Devices and Metric Halo (sadly Mac only) and you would notice
the noise difference between these and the DR680 which is our
recommendation for an inexpensive portable device.
My experience is if you are not recording bird song in the Norfolk Broads,
the noise performance of TetraMic wth the above good preamps is not a
problem. There are some excellent recordings on Ambisonia from John
Leonard & Paul Hodges .. some of which were made in a very quiet studio.
That's not to say we aren't working on even better performance ... 8>D
(There are problems with noise on the P48V on early DR680s and Paul Hodges
has a mod for these on Channels 1-4. I believe, TASCAM, Europe were
modifying Mk1 DR680s and the new one has sorted this out.
If you have an old DR680, it is worth doing Paul's mod as it affects some
mikes, both $$$ & inexpensive. TetraMic is actually pretty immune to P48V
If you have a good A/D without preamps, you can build a 4 channel preamp
using THAT chips with near SOTA performance.
Bear in mind you need to match THAT 1510s & 1512s for gain. The internal
resistors are laser trimmed for CMR but the absolute values differ from
chip to chip. Thanks to David Pickett for this tip.
If you prefer to use SSM2019 or TI INA163 chips, use them with the latest
THAT circuits for more reliable long term performance. All three are
capable of excellent performance in the right circuit.
It's the protection scheme that is flawed on the SSM, TI & (very early)
THAT circuits. The correct protection is cheapo 1n4004 diodes, preferable
Glass Passivated 1n4004GP.
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