ghost outputs

[ichabodzips]

Thinking about purchasing a ghost 32 channel due to its rave reviews on this bbs but I was concerned about the tape_outs not being balanced. Planning on hooking intoh my DAW through A/D/A converters via the tape_outs. Anyone have a similar setup or run into problems with noise from the unbalanced outs?

Thanks

 

[skippy]

I do exactly that with my Ghost. No problems at all: those outputs work very well. They aren't aren't fully differential, but they aren't purely single-ended either: they are "ground compensated" which is a Britishism for pseudo-balanced, or impedance-balanced. Sounds wishy-washy, but it is a cost saving measure that is actually based on sound design principles.

The outputs are configured to actually drive pin 2/tip, and then pin 3/ring is connected to signal ground via a resistor that has essentially the same impedance as the output driver. External noise sources will then couple the same common-mode noise signal on both pin 2 and pin 3, since the source impedances are the same, and that allows the balanced input being driven to cancel out the common mode noise just as if it was a full differential driver. You just end up with 6dB less voltage swing. The key is matching the impedance on the non-driven pin 3 line to the impedance of the driven pin 2 line: the better job you do at that, the better the common-mode rejection will be. Soundcraft uses a very low impedance driver, so I believe that they simply tie pin 3 directly to signal ground...

So as far as noise cancellation goes, you still get most of the benefits of a fully balanced connection- but you only have to _pay_ for half the driver circuitry. I've gone through and done the measurements on mine (thanks to RME's wonderful Digicheck utility), and the combination of Ghost output driving A/D input (with all faders down) still sits right at my A/D's intrinsic noise floor at -111 dBfs: this is a real-world measurement. This is also *damned fine performance* in my book.

Note that you can do this "ground compensation" trick to *any* single-ended output, by the way (by changing out connectors and locating the proper signal ground reference). It's not a Soundcraft-specific thing: they just make it very, very easy for you by building it in...

 

[ichabodzips]

Thanks for clearing that up.

I am going to be using RME 9652 for the DAW card, how do you setup your timecode sync between the ghost and your DAW. I am guessing the ghost would be set to master and the hammerfall to slave?

 

[skippy]

No, the other way around. I still subscribe to the old philosophy of "the recorder is the master", so I always use the Ghost as a slave. I have a pretty complex rig, but here's what I do- some of it may help.

The DAW is Cubase with a Hammerfall. I also use a Fostex D1624 mulltitrack. The Fostex is the system timecode master, in almost all cases. It is set up to listen to Sony 9-pin protocol machine control from the Ghost, so I can use the machine control on the Ghost to play, start, stop, and so on on the Fostex. The Fostex is set up to output MTC, which I then run to the DAW (via a Midex-8). The DAW is set up to chase the incoming timecode from the Fostex, and then output MTC of its own- which I then run to a JLCooper MTC-SMPTE converter to drive the Ghost's timecode display. I needed to go to SMPTE because the Fostex's 9-pin protocol has really lousy MTC sync behavior. It sends its timecode in bursts in play and record mode, so accurate mute automation is a lost cause. SMPTE derived from the unit's native MTC has proven to be more reliable.

This roundabout routing lets me use the DAW without the Fostex, and still get timecode to the Ghost for using the board's automation- I don't get machine control without the Fostex, but once I'm on the DAW and mixing with the mouse anyway, I can cope with that. I normally track to the Fostex, because of a native distrust of computer recording, and then later fly the tracks in for editing, archiving and so on.

When not using the Fostex, I suppose I could easily reconfigure the Ghost to do MMC (instead of 9-pin) to directly control the DAW and repatch the Ghost's midi out to drive a spare input on the DAW. But I haven't bothered much with this yet, other than to prove that it worked one time... I find it much more powerful to be able to work on the Fostex and DAW simultaneously, so just having the Ghost control the Fostex, and the DAW chasing it, works best for me...

 

[TexRoadkill]

Skippy- Do you bounce back to the Fostex after editing in the DAW and mixdown through the Ghost? Do you have any mixes on the net?

 

[skippy]

Typically, no: once I move to the DAW I generally just stay there. Stuff that has a lot of MIDI, or needs a lot of editing, goes to the DAW and stays there. Stuff that is basically one-take (the vast majority of my work) stays on the Fostex, except that I always fly over a backup copy to the DAW so that I can back it off onto 8mm tape for safekeeping. I do have one or two projects that are half-Fostex, half-DAW, mostly just as a vehicle to work with the timecode technology and learn its pitfalls and advantages, just to try to learn some of these newfangled tricks. Those could be all-DAW, of course.

Truth be told, I'm still not that enamored of the DAW: I like to think of the Fostex as a very small 2" tape machine, and work just the way I used to, with the machine control right in front of me on the board... I use my Masterlink as the 2-track, just the same way. I *know* I could do it all on the DAW- but I just don't like working that way. Too many BSODs, too much risk (although going to XP certainly has improved that situation). I'll fart around with my own sandbox material there as a learning process, but the stuff that really matters (defined as: money changing hands)pretty much stays on the Fostex. I'm too much of a throwback.

I have an RME ADI-8 I use so that I can record 16 tracks at once to the Fostex. That actually gives me 24 D/A converters all told (the Fostex has 16 out, but only 8 in). It *is* nice to be able to set up Cubase with 24 outputs, and play back the DAW as if it was a tape machine, doing all the mixing in the familiar old analog domain... That fits with my brain much better than mixing with the mouse- and still lets me use a few favorite plugins here and there. Maybe in the coming years I'll get more comfortable with the DAW thing, and start using it more fully. It's not the first tool I reach for in the toolbox, though.

No, there aren't any of my current mixes on the net. I don't have the rights to post any of my works-for-hire, and I don't have any inclination to post my own material... You could probably find some stuff I did back in the 80s with a little digging, though.