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  #1  
Old 12-27-2017, 12:58 PM
bicoman@sofnet.com bicoman@sofnet.com is offline
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Default Tryint to use SPDIF with digi rack 002

I've have slowly been trying to build up a recording system that will have a high degree of fidelity for recording mostly acoustic music. To that end I have a separate mic pre and A/D converter. (The sound I am getting directly out of my mic pre into phones is quite nice!) I'm running the A/D at 96K into the SPDIF of a digi rack 002 in the hopes that the Digi 002 will take the SPDIF and run it directly to the firewire port into PT and onto disc. However, after recording some acoustic guitar, setting my outputs for the track to SPDIF, and running it out to a D/A converter and into some monitors, the sound is quite a bit less splendid than even what I'm hearing in the headphone out of the digi 002, let alone directly out of the mic pre. My question is: Am I getting the digital data directly to the disc? If not how can I?
Equipment:
Shure SM81 (Guitar is stereo miked)
Miktek MK300
SPL MikeMan Mic pre
Ross Martin PCM4222 ADC
Digi Rack 002
Audio Technica ATH M50x Phones
Schiit Modi 2u D/A Converter
JBL LSR 308 Monitors

Thanks in Advance
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  #2  
Old 12-27-2017, 02:02 PM
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Top Jimmy Top Jimmy is offline
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Default Re: Tryint to use SPDIF with digi rack 002

Quote:
Originally Posted by bicoman@sofnet.com View Post
Am I getting the digital data directly to the disc?
Short answer: Yes.

You attest to the fact that things sound great in your headphones coming out of the 002. So if this is good, why aren't you suspicious of the last element in the playback chain? I would first look to the monitors as the chief suspect in less than expected sound quality.
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  #3  
Old 12-27-2017, 02:03 PM
Darryl Ramm Darryl Ramm is offline
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Default Re: Tryint to use SPDIF with digi rack 002

Hi Welcome to DUC.

If you are recording anything and the mic is connected to an outboard S/PDIF preamp then the signal it is coming via S/PDIF digital and its digital and stays digital to disk, but I'm not sure how that is relevant here. If you play back on headphones and that sounds better than your monitors then the most likely thing is causing a difference is the monitors/room. Compare one thing at a time. Have you got the room acoustic under control? You have a well regarded but low-end pair of monitors, are you playing back at a similar SPL to the headphones, etc.

Nobody has a hope of guessing what "less splendid" means. You need to he able to work at at least describe to yourself what the audible difference is.

You may benefit by making things simpler why you understand things, e.g. get rid of all the external stuff and just play wth the 002 driving headphones vs. monitors. And focus on that, room treatment, etc.

I'd tend to be thinking about upgrading/spending more on monitors (I'd argue they are often the most important thing to spend $ on) before buying outboards DACs But again, you can A/B the DAC and tell for yourself if you think that is worthwhile.
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Old 12-27-2017, 03:12 PM
bicoman@sofnet.com bicoman@sofnet.com is offline
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Default Re: Tryint to use SPDIF with digi rack 002

Point well taken. In my phones I hear a glassy, rich, airy sound. The bass is full even with light gauge strings and a capo. My voice sounds transparent with a bit of 'snap' in the upper frequencies. You can hear an audible sort of click when my lips part at times.

Coming out of the monitors, the crispness of the highs is gone and the bass sounds muffled, weak. But the vocals are the worst. It sounds as bad or worse than when I was just using a straight digi002 with a dynamic mike.

The reason I became suspicious that I was not getting direct digital was that the headphone out on the digi works. Some there is some D/A converting going on somewhere.

I will take your advice and try to isolate the issue. However, one thing you mentioned may be the issue. I am recording in a room with virtually zero treatments. Cement floor with only a small rug, chipboard walls, no curtains and mostly empty. That might explain why the phones sound good but not the monitors. It's basically a workshop.

Thanks for you advice.
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  #5  
Old 12-27-2017, 05:15 PM
Darryl Ramm Darryl Ramm is offline
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Default Re: Tryint to use SPDIF with digi rack 002

I suspect you have lots to do with setting up that room...


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  #6  
Old 12-28-2017, 06:53 PM
albee1952 albee1952 is offline
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Default Re: Tryint to use SPDIF with digi rack 002

Couple of questions:
Describe the connections between each piece(preamp>ADC>002>session settings>oo2>DAC>Monitors)
Clock settings?
Are the digital connections done with genuine digital cables(and not some old red&white RCA cables for an old cassette deck)?
How are you figuring gain staging on the way in?
How are the acoustics in the room? This can make a huge impact on the sound. I also use the MK300 with an AT4041 and get really good acoustic tracks(even at 48K). I ask about the room acoustics as I use the MK300 in figure 8(but my room is well-treated)
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  #7  
Old 12-29-2017, 06:22 AM
bicoman@sofnet.com bicoman@sofnet.com is offline
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Default Re: Tryint to use SPDIF with digi rack 002

The Input connections are:
Preamp to ADC -> balanced XLR.
ADC to DIGI 002 (SPDIF) -> Shielded RCA.
DIGI 002 to Computer -> Standard Firewire

The output Connections are:
DIGI 002 to Schiit Modi DAC -> Rca
Modi DAC to JBL monitors -> Shielded Rca to 1/4 jack.

The SPDIF RCA cable is from a AV system. Beefy with good shielding.

My clock is 96K.

I agree with you that the mk300 is probably not the problem.

My gain works out about like this:
My preamp gains are 44db for the SM81 and 38db for the mk300 (The preamp has 72db of gain, so I am not pushing it). The ADC has a 10db pad on both inputs turned on and my mix slider is set to 0db.
Nothing is going into the red unless I accidentally smack the mic stand with the guitar or something. I'm monitoring the recording process on my headphones through the DIGI phone out. The sound there is not as crisp and airy as straight out of the preamp, but I am not detecting any gain overdrive.

I am also using the mk300 in a figure 8, positioned perpendicular to the neck of the guitar.

My room may be the problem. It's little more than a workshop with cement floor, no curtains, chipboard walls. I was not aware that room treatments could effect the sound so profoundly.

At this point I will need to do some research on room treatments as I know virtually nothing about it. I'm thinking that one solution may be for me to build a small room within my studio and treat it. It's just me, a guitar or keyboard and a few microphones. Wouldn't need to be very big.

Thanks for taking the time to read and reply!!!
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Old 12-29-2017, 08:16 AM
albee1952 albee1952 is offline
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Default Re: Tryint to use SPDIF with digi rack 002

Good detail^^^ Random thoughts:
"Modi DAC to JBL monitors -> Shielded Rca to 1/4 jack." Why RCA? Is that the only analog option to feed the speakers? Unbalanced connections are much more prone to picking up interference

"The sound there is not as crisp and airy as straight out of the preamp" Hmmm, this seems to point to this unit as suspect

Room acoustics probably make a bigger difference than the mics, the preamps, the converters AND using 96K In fact, I'd wager a 6 pack of your favorite beer that if you ran another pass at 48K, you probably couldn't tell which was which if someone played the 2 versions without you knowing My booth for acoustics is treated with 1" and 2" 703 panels on 2 sides, auralex foam on a 3rd side and the back wall is 6" of rockwool with an air space behind.
Acoustic tiles on the ceiling and carpet on the floor
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The better I drink...the more I mix.....

BTW, my name is Dave, but most people call me.........................Dave
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  #9  
Old 12-30-2017, 06:55 AM
bicoman@sofnet.com bicoman@sofnet.com is offline
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Default Re: Tryint to use SPDIF with digi rack 002

Thanks for the reply Dave.
I'm not sure if my monitors have balanced inputs, I'll have to check when I get back home tomorrow. I guess I could be having phase problems too. At this point I'm beginning to suspect that the Schiit DAC is not going to cut it. Will probably need to get a real studio quality DAC with balanced outputs.

Well yes the DIGI 002 preamps and converter are suspect. That's why I'm trying to go SPDIF then firewire to disk. The fact that the DIGI headphone outputs were working at all is what originally made me suspect that I was maybe not getting digital directly from my ADC to the disk. The DIGI has to be running ADC on the SPDIF because there is no analog connection to it.

And thanks for the info on your room treatments, that will give me a place to start researching.

About what size is your acoustic room?

BTW, my name is Mike.......... but no one calls me Dave.
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  #10  
Old 01-10-2018, 09:48 AM
albee1952 albee1952 is offline
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Default Re: Tryint to use SPDIF with digi rack 002

My current room WAS 8' square, which is a terrible idea(still want to shoot the person that built this place). So, I built a 2x6 stud wall a foot away from the back wall, filled it with 6" rock wool(leaving an air gap) and covered it with burlap. The other 3 walls have a mix of 1" 703 panels, 2" 703 panels and some Auralex on the last wall and front corners. The ceiling is acoustical tiles and the concrete floor has carpeting. The panels are spread out so the walls are not completely covered so the room is not too "dead"
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BTW, my name is Dave, but most people call me.........................Dave
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