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Usbpre2 sync with D50...
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Salty Heaven
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#1
15th September 2013
Old 15th September 2013
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Usbpre2 sync with D50...

I wan't sure which forum to place this in so by all means shift it if you like....

----------------------------------

Hi all,

Is there anyone here that can shed some light on this for me...

My most favourite and used piece of equipment is my Usbpre 2, 90% of the time it is everything I need.
Occasionally, I would like to be able to record 4 tracks at once though.
My little portable rig consists of a Sony D50 piggybacked to a Denecke PS2 phantom power supply. I have been trying to get the Usbpre and the D50 to sync clocks via optical SPDIF.
I have had it confirmed from Sound Devices that this should be possible and that indeed it does appear to be happening because I get solid green SPDIF LEDs on the usbpre 2.

However, when I import the D50 audio into my daw and line things up I'm getting a drift of 120 samples or so in a minute. Plenty to give me all sorts of phase issues.

I've triple checked that sample rates are set alike across all devices. I've sent a further query to Sound Devices but have not yet received a reply...

If I had the money I'd buy a 744 and be done with it, alas that is not to be...

cheers,
#2
15th September 2013
Old 15th September 2013
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Masaaki is offline
I wonder how you record signals from USBpre2 and D50 simultaneously, and where you write the data. IIRC, D50 is a stereo PCM recorder, right? Are you using USBpre2 to computer, and writing the data to computer, while capturing mic signals by D50 and writing the data to SD card? I don't understand the green light of USBpre2 is on, that means you are using D50 as a clock master, and USBpre2 is a clock slave?

More detailed information, re: how you connect and how you record, sample rate, clock master/slave etc, will help troubleshooting.
Salty Heaven
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15th September 2013
Old 15th September 2013
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Hi Masaaki, thanks for taking the time to respond.

The Usbpre 2 is in interface mode and sending the signal from it's mic inputs via usb to my laptop.
The D50 is taking 2 more mic inputs via the denecke ps2 and recording to its internal memory.
I have an optical cable going out from the D50 into the Usbpre. This cable carries the D50 signal, all of which is ignored by the usbpre except the clock information.

The idea is that the usbpre will sync it's clock with an external digital signal connected to its spdif input and ignore the content of that same digital input whilst passing the audio from the mic inputs onward. The theory is sound.
This reply came from Sound Devices:

-------

"There shouldn't be an issue syncing to an external device in interface mode. It does appear that the USBPre 2 is locking to the incoming rate since the SPDIF LED's are solid instead of blinking. The main other thing to make sure of is that the software driver sample rate is set to the same rate that the D50 is set to. Also make sure whatever software you are using is also matching the sample rate.

Casey Luft
Sound Devices, LLC

-------

After stopping the recording I have to load the files from the D50 into my DAW and line them up with the ones that were recorded directly in. Not ideal, I'm happy to admit, however I own the gear and really don't need more than two tracks except on rare occasions.

Does this make sense now? It's actually way quicker and easier to do than to explain in writing it just doesn't happen to be working : (
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15th September 2013
Old 15th September 2013
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Okay, thanks, I think I got how you're doing this. Basically you are aligning manually two independent recordings, one written to laptop, another written to the internal memory of D50, using your DAW, right?

In theory, if these recordings were done using the same sample rate with a system of one device sync-locked to another device, there shouldn't be drift as SD tech support says. The problem is how you manually align these recordings, and another thing is how you make sure, particularly the one that's written by laptop doesn't have any drop.

I wonder you are using class compliant mode to write to the laptop, or using ASIO driver they have. Your laptop, particularly if it is netbook or something, may not be writing the data completely. So, that's one thing you may need to check first.

Another thing you may want to try is to do the null test for the beginning of the recording, say 00:00 to 00:05. Then later part, try null test say 00:60 to 00:65 data. If it's a drift, the beginning of the recording perfectly nulls, while they don't null for the 60-65 sec part. Then, manually re-align the 60-65 sec part so that they null again, try null test at 01:00-01:05.

This is just my guess, but if you import those recording to your DAW and 'line them up' simply aligning the beginning of the 'files', the one written by the computer (through USBpre2) and the one written by D50 have different buffer (delay) timing for the actual audio signals. Computer writing is based on the ASIO driver setup, like 64, 128, or 256 samples or the system buffer if it is class compliant mode. I don't know what is the buffer for D50, but there should be some. If there isn't a drift, the delay relation should be consistent, and they should perfectly null throughout the recording, by nudging one a few samples to match the actually audio. So, the 'line them up' should be done really for the actually audio, that is not actually easy thing to do in a real life. In fact, this is actually the case that requires time code recording.

After all, if you don't need more than 2ch, this is just a invitation of hassle, and the data should be written using single device while the signals may come from sync'ed multiple devices.
Salty Heaven
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#5
16th September 2013
Old 16th September 2013
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Thanks Masaaki,

Yes, you've got the overview. Great.

I'm using the ASIO driver for the Usbpre2, the laptop is the latest model Samsung Series 9 with an i5 3317 running windows7. REAPER is my DAW.

My process has been to start the recorders at roughly the same time, slate the recording with a sharp sound at the beginning and end, import the audio and align the slates manually.
I hadn't thought of doing a null test although I've just done that now: I can align the slate at the beginning of the recording such that it nulls (almost, but not quite a perfect null) then looking at the slate at the end of the recording it is clearly and obviously way out of alignment. I can then line that slate up and null it, however (obviously) going back to the start of the recording I'm out of alignment again. The drift is about 120 samples per minute of recording.

Although I take your point that I may be inviting more hassle than I need, I still am getting an apparent drift in clocks that are supposedly synced.

I don't know anything about timecode other than a general understanding of its intent and that it costs a lot!

With your greater experience, if you had to record to two different devices that were clock synced and then align them manually like I'm describing, do you think it would work? By 'work' I mean do you think it would be possible to align them such that no weird artefacts occurred?
I think I can align my slates to within a sample, is that enough? After all, at 48khz, sound travels 7mm per sample (I hope I got that maths right) so if the mics are a typical couple of feet or further apart, within a sample seems to me that it would be adequate, as long as that same alignment is maintained.

Thanks again for your time, I appreciate it.

Cheers
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16th September 2013
Old 16th September 2013
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At the moment, I don't have obvious explanation for the drift, but from your tests, it does indeed sound like consistent drift. I just wanted to make sure it is not a mis-alignment.

I thought about poor quality of clock signals in D50 (literally jitter) as a possible cause of the drift, but if the USBpre2 is perfectly in sync, then it should still record the data at bit-by-bit accuracy. Otherwise, 120sample/60 seconds means, 2 sample/sec and there may be dropped samples at that rate, and accumulate over time. For that explanation, I have to assume USBpre2 is unable to lock for the incoming sync signal, 2 samples in one second.

I don't know your D50 is able to sync to external (I doubt), but you may want to try if you can. Another thing is to use other higher sample rate, such as 88.2 or 96kHz to see if the drift is different in either way (better or worse).

I'm not really giving solid ideas, so I stop here, but hope others reading the detailed information, and tell you 'the' reason.
Salty Heaven
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16th September 2013
Old 16th September 2013
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Cool. I'll try higher sample rates.

Thanks again for your efforts, all the best to you.
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16th September 2013
Old 16th September 2013
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romphoneiu is offline
Also make sure whatever software you are using is also matching the sample rate.
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16th September 2013
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romphoneiu is offline
Also make sure whatever software you are using is also matching the sample rate.
Salty Heaven
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16th September 2013
Old 16th September 2013
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Thanks romphoneiu, My DAW (REAPER) is set to a matching sample rate, as is the Win7 sound driver even though we're not using it I thought it couldn't hurt.

Further information for anyone else that may have some input:

At 44.1 the drift is a repeatable 15 samples per minute.
At 48 again repeatable.. 120 samples per minute.
At 96 same... 120 samples per minute.

There's not really a pattern here, however every time I run a trial at a given sample rate I get the same result.

Sounds to me like there is some kind of core level incompatibility, or strange functionality in one of the devices and I should probably give up the game...
Salty Heaven
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16th September 2013
Old 16th September 2013
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#12
17th September 2013
Old 17th September 2013
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Do you have any other devices that have a better clock?
I guess it all comes down to the quality of the clock in D50, and jitter, but without having a reference, it's hard to say that's the reason.

I can test my Tascam DR100mkII (which might be a similar quality as D50), with my USBpre2, but maybe I can try this with my other ADC (RME, Mytek, Benchmark) with USBpre2 slaved, and recorded to tow separate computers.

It's going to take some time though....
#13
17th September 2013
Old 17th September 2013
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So, I did some tests, although not exactly the one I mentioned above, but this is probably useful information.

I connected TOSLINK optical cable from RME sound card, that is installed in computer (A), to USBpre2's optical IN. The RME card (HDSPe AIO) was clocked internally at 48kHz, and the signal was changed to S/PDIF. So, basically this TOSLINK cable provides S/PDIF clocking information to USBpre2, as described in the USBpre2's manual. S/PDIF indicators were solid green, and no blinking/flashing, indicating it locked to the external clock source.

Then, I connected USB cable from USBpre2 to another computer (B) which has Reaper and ASIO driver. So the set up was similar to the OP's, except for I used computer A and the RME card to clock USBpre2, instead of D50.

Then, I set up ASIO driver in the computer B to record incoming signals (I fed line in signals to the USBpre2 from a CD player) at sample rate 44.1kHz. The recording was glitch free (no pops/clicks), and the S/PDIF indicator was solid green (no blinking/flashing).

So, this tells one thing. When you connect USBpre2 to computer via USB cable, and use the ASIO driver, the driver can (and very likely WILL) override the clocking source, even S/PDIF signals are coming in to the unit via TOSLINK port.

Now OP used 44.1kHz sync signal from D50 via optical cable going to USBpre2, and set up laptop's ASIO driver again at 44.1kHz. That means, the ASIO driver overrode the clock, and USBpre2 was capturing the signals using the internal clock (not the external clock signal from D50).

Does this make sense?

So, if you have two devices, each having 44.1kHz internal clock and record separately, they would never be bit-accurate, because the samples were done by independent clock.

To alleviate this problem, USBpre2 needs to be truly clocked by external source, while sending out signals. I think that's possible using optical OUT port for the USBpre2 even this is really convoluted solution.

First, to power the USBpre2, just use USB battery power pack (so that no information from the computer overrides). Connect sync signal from D50 to USBpre2 using optical cable as you did. Then, connect another optical cable from the optical OUT (S/PDIF) of the USBpre2 to has S/PDIF input, record the digital signals. If you do this, clocking of D50 and USBpre2 should be locked, and the data should be bit-accurate.

Hope you understand what I'm talking......
Salty Heaven
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17th September 2013
Old 17th September 2013
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Awesome! Thanks Masaaki. You have confirmed where the issue lays for me.

Yes, you're making perfect sense.

I have got a USB battery pack but my only digital in devices are the D50 and a computer so that doesn't really get me anywhere and, as you say, it's getting really convoluted.

I have posted on the REAPER forum to see if anything can be done about the computer/REAPER overriding the clock. Also Sound Devices have offered to run a few test of their own (aren't they great?).
If neither of these avenues bear fruit I daresay I'm better off finding an alternative solution.

Thanks again for your help and for doing those tests. I'll post here when I have an outcome.


Cheers.
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17th September 2013
Old 17th September 2013
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Hi, I did the battery-powered USBpre2 and external sync test, just briefly.

I sent out clock signal from the RME card (AIO), like 44.1, 48, 88.2, or 96kHz via S/PDIF cable to USBpre2 which is powered by a battery pack (Anker Astro). Then, connected TOSLINK OUT of the USBpre2 to my RME UFX to see if the UFX locks to the incoming external clock signals. When I changed the sample rate of the AIO card, UFX's sample rate changed accordingly, and the lock status indicator was perfectly stable. I didn't do any recordings to confirm they are bit-accurate or not, but I assume they will match 'nicely'. Manual aligning won't null anyway (b/c signals go through different analog domains), but they won't have 120 samples/min drift. Again....in theory.

The best route to report this information is Sound Devices, particularly their driver development. Other ASIO drivers, like RME's, usually have an ability to choose internal clock or external clock. USBpre2's ASIO driver doesn't have such options. So, if they can add such option (hopefully), you would be able to tell USBpre2 to clock to external source, while it's still connected to the computer.

The ASIO driver looks like ASIO4ALL, but when I installed USBpre's ASIO driver, I briefly saw some German words, so their driver may be OEM'ed by RME. If that is the case, you have the best hope. But, it's just my wild guess, and who knows...oh, talking about ASIO4ALL, I haven't checked if it has internal/external clock option. You might want to check that.

Anyway, I was driven by curiosity, but I also own the USBpre2, and if this brings a little bit of functional improvement, it's good for me too.

Good luck!
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17th September 2013
Old 17th September 2013
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David Spearritt is offline
Quote:
Originally Posted by Masaaki View Post
The ASIO driver looks like ASIO4ALL, but when I installed USBpre's ASIO driver, I briefly saw some German words, so their driver may be OEM'ed by RME. If that is the case, you have the best hope. But, it's just my wild guess, and who knows...
Nope. It's written by Ploytec and they also sell one of their own.

You can see this in Device Manager, right click the USBPre2, choose Properties, then Driver tab. The Provider and DigitalSigner is Ploytec.

BTW, I spent the weekend finding out that the USBPre2 does not work correctly on a USB3 port (Fresco Logic Controller in this case). This is a huge problem as some modern laptops now only have USB3 ports.
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17th September 2013
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Thanks David! I confirmed that.

As to the USB3 compatibility, ASMedia and Renesus controllers (both desktops) working fine here, but I don't know what's your 'not work correctly'. I know this is OT for the OP, but helpful information in a general sense, so would you tell us a little bit more?
Salty Heaven
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17th September 2013
Old 17th September 2013
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Thanks Masaaki, that was a pretty cool test! It further confirms what is going on. You're not short of sound cards are you!

I have one each USB3 and USB2 port, it works the same in both.

Don't worry about going off topic, it's all good interesting stuff.

I'll wait to hear back from Sound Devices and let you all know what they say...
#19
18th September 2013
Old 18th September 2013
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Quote:
Originally Posted by Salty Heaven View Post
Thanks Masaaki, that was a pretty cool test! It further confirms what is going on. You're not short of sound cards are you!
Haha..indeed. I like PCI/PCIe cards for the desktop, and use UFX as a main interface for location. USBpre2 is actually a backup, but these days, I bring just USBpre2 and Tascam DR100mk2 with a couple of mics. That's because video equipment is getting more and more.....

Hope you hear from SD soon, and let me know if they ask something about what I did. I actually need to register my USBpre2 (..geez....that's a good reminder for myself...).

Best,
#20
19th September 2013
Old 19th September 2013
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Quote:
Originally Posted by Masaaki View Post
As to the USB3 compatibility, ASMedia and Renesus controllers (both desktops) working fine here, but I don't know what's your 'not work correctly'. I know this is OT for the OP, but helpful information in a general sense, so would you tell us a little bit more?
I am using an ASUS G73SW with a Fresco Logic USB3 controller, Windows 7_64. I cannot get the USBPre2 to work reliably on this port. The Ploytec ASIO driver hangs both PMX 8.1.8 and Wavelab 6, when trying to change sample rates or load the ASIO Control Panel. The installation half works as well, this was a clue. It seems the controller driver software might be the culprit. Latest from ASUS is installed.

When plugged into a USB2 port, all is fine.
Salty Heaven
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13th October 2013
Old 13th October 2013
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Well, I never did get a further reply from Sound Devices. I don't hold it against them, they primarily supply professionals and I'm small fry trying to do something a bit odd to save a few bucks.
Final word from me: It seems that the Usbpre 2 wont sync while in interface mode with my current setup and equipment. Nevermind.

Thanks all for your efforts all the same.

Cheers, Mikey
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13th October 2013
Old 13th October 2013
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Hi,

It took for a while to understand what we were talking....seems like long time ago.

Anyway, the issue is using USBpre2 on external clock, while connecting via USB cable to computer, right? They may be working on it, or just testing it whether this is really their problem or not. It could take a while to revise device drivers, so you may send some 'friendly' reminder every couple of month? I would do that if I'm desperate.

To be honest, for 4ch recording, this isn't really a good way and requires a lot of hassle and inaccuracy (manual align), so it's up to your priority how much you push on this end. Overall, as you mentioned in the first place, USBpre2 is a fantastic device.

Good luck.
Salty Heaven
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#23
19th October 2013
Old 19th October 2013
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spot on masaaki. agreed agreed agreed.

I've been concentrating on stereo recordings with the odd overdub and enjoying the beautiful simplicity and magical sound of the usbpre. I'm happy.

Thanks again for your efforts with this.
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