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TTM-57SL - Q about the DSP processing
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TTM-57SL - Q about the DSP processing

Deft 7:14 AM - 30 April, 2006
I noticed that pretty much everything in the TTM-57SL is handled by DSP, even the EQ, is that right? (obviously apart from the input/output stages!).
Now that the production runs will begin to trickle out, have Rane or Serato got any feeling about it subjectively sounding any different to the 56 (which I assume has no DSP in it anywhere).
I'm not looking for a 'better' or 'worse' kind of argument, but do they feel it has a different sound character to the 56?

Also - I think it was mentioned that there were plans to allow vinyl control + post-fader recording of each channel simultaneously, just that it hadn't been implemented yet. Is this still planned (rather than just master record whilst using control vinyl/cds).
Thanks
nik39 10:19 AM - 30 April, 2006
Deft, good questions. I am not an official, but there are some good hints in the manual, worth checking it out at www.rane.com <-click. It says:

Quote:
HIGH / MID / LOW EQ
The control range is OFF to +6 dB. These use 2nd-order, Linkwitz-
Riley, Accelerated Slope™ filters.


Quote:
USB Streaming Audio
There are up to eight channels of streaming
audio over the USB port. Two stereo
channels from the computer and two stereo
channels to the computer. While internal
processing is all 24-bit 44.1 kHz, streaming
audio is 16-bit 44.1 kHz. If the blue indicator
is on, the device is connected and communicating with the
computer.
Two stereo signals from the computer appear as Digital 1
and Digital 2 inputs. These stereo digital signals may be selected
for PGM 1 and/or PGM 2 (see source selection in Program
Controls section).
Two stereo channels are sent to the computer. These may be
two independent stereo audio streams for recording -or- one stereo
audio stream for recording and one 4-channel TDM stream
for vinyl emulation control. Scratch LIVE software selects the
record and vinyl emulation control sources.
When not using Scratch LIVE, the mixer appears as an 8-
channel sound card with two stereo channels in and two stereo
channels out. The source for the stereo output channels must be
selected in software.
The following signals may be selected as the source for either
digital output to the computer:
PGM 1 Pre- or Post- Fader
PGM 2 Pre- or Post-Fader
Main Mix
AUX BUS (sum of MIC, AUX and FlexFX Return).
nik39 1:35 PM - 30 April, 2006
Wow, did you check

Appendix
Simplified block diagram of the analog inputs around the DSP. Only one channel is shown.

?

Looks like all the signal processing is done via the DSPs means its completely digital (except the Mic EQ, from the diagram it seems like this is the only analog signal altering).

I think we also need a news TTM57 section at the ssl-wiki, after reading the manual it seems like there might arise a lot of questions.
Deft 2:51 PM - 30 April, 2006
Well that's what originally made me post the question - but my understanding of how you interface all the bits inside a mixer isn't great (e.g. the VCA fader control into the DSP etc).
Also, if Serato manage to squeeze enough bandwidth out of USB1.1 to allow vinyl control plus two discreet post-fader recording feeds for PGM1 and PGM2 then they get a small gold star.
If they don't, however, it will involve some kind of ritual burning at the stake whilst chanting "USB2.0".
Spelunk 3:05 AM - 1 May, 2006
This is an interesting question, would be cool to see it answered by Rane.
Spelunk 4:32 PM - 5 May, 2006
Oh I wasn't asking for a subjective opinion about how it sounds, just to clarify what parts are analog and what are DSP. That's strange about the dynamic range, but I'm not too concerned.

So given the 57 is very DSP driven, I've got a question. If you're recording a scratchlive performance, does the signal stay digital the entire time or is it converted to analog and then back to digital because of the FlexFX loop?
Spelunk 4:36 PM - 7 May, 2006
Thanks for answering the question, now I get how the design works, awesome stuff, because it means if you don't want to you never degrade your signal if you do something like scratch a beat, record that beat, and then play or scratch that.

I really had no idea the 57 was so heavily based in DSP, but I'm really starting to like the idea.