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Author Topic: Sound Devices USBPre2 (Part Duex)  (Read 16991 times)

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Offline acidjack

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #15 on: December 29, 2011, 11:11:21 AM »
Not the limiter but have been using the 15dB pad.  Found that it was all I needed even when using mics on stage.

I've use the pad, all the time, have to. I ran my ck950s couple weeks ago with the gain turned all the way down, 15db pad in, and peaked around -5.  :o

Same.  Without the pad I found the signal to be way, way too hot almost all the time.  I still run the Schoeps at only about 1/4 of the gain wheel, the DPAs just a hair more.
Mics: Schoeps MK4V, MK41V, MK5, MK22> CMC6, KCY 250/5, KC5, NBob; MBHO MBP603/KA200N, AT 3031, DPA 4061 w/ d:vice, Naiant X-X, AT 853c, shotgun, Nak300
Pres/Power: Aerco MP2, tinybox v2  [KCY], CA-UBB
Decks: Sound Devices MixPre 6, Zoom F8, M10, D50

My recordings on nyctaper.com: http://www.nyctaper.com/?tag=acidjack | LMA: http://www.archive.org/bookmarks/acidjack | twitter: http://www.twitter.com/acidjacknyc | Soundcloud: https://soundcloud.com/acidjacknyc

Offline yug du nord

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #16 on: December 29, 2011, 11:20:03 AM »
Are the 7xx series pre's that hot too?  Same pre's right??
Reminds me of the "hotness" of the MixPre.
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Re: Sound Devices USBPre2 (Part Duex)
« Reply #17 on: December 29, 2011, 10:07:21 PM »
Are the 7xx series pre's that hot too?  Same pre's right??

the usbpre2 uses the same preamps as the 788 (at least thats what SD says, I'm inclined to believe them).

The difference comes in the max input before clipping values. I can throw just under +10dbu at my 722 in mic-in mode and clip it, that would clip the usbpre2 though (which is -10dbu and +4dbu if you use the pad). Yes, the pre2 sounds the same as it's bigger brother, but the 7 series have a series of features that other boxes in the SD line don't have.

Anyway, here is how I figured out what to do before showing up at a concert:

  • I know the max input before clipping on the pre2 with out pad is a paltry -10dbu
  • With the pad, it's +4dbu (or really close, that's the official printed spec)
  • Based on the mic transfer chart (half way down), and the official beyer 950 literature, they have a max output before clipping of +3dbu. The 930s max out at +4dbu because of a slightly higher headroom and mildly lower output rating.
  • While very loud, I've never clipped the mics in this room for a similar act before based on post-prod/backwards calculation of SPL from older recordings I made with my 722 and it's printed gain ratings (which I was really good about writing down for a while)

So given all of this information, I knew I could turn the gain all the way down, and the mic and preamp would crap out at roughly the same time (which in theory is optimum as long as you know you won't hit that, but will come close).

It's an awesome box, case in point, today I was at a friends house who had a DAC that accepted SPDIF (RCA) and I didn't have that out of my macbook, so I fed the optical to the pre2 and a spdif out of that. SD said it doesn't resample so it acted like one of the older Hosa276 converter boxes. It just has some quirks that people need to keep in consideration is all.
"This is a common practice we have on the bus; debating facts that we could easily find through printed material. It's like, how far is it today? I think it's four hours, and someone else comes in at 11 hours, and well, then we'll... just... talk about it..." - Jeb Puryear

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #18 on: January 26, 2012, 11:24:42 PM »
any suggestions on on what input i should use: 
external pre (with unbalanced output) > usbpre2

are the xlr's strictly mic inputs?  or can they be fed a line signal?
is there any difference between the 1/4" LINE and rca AUX inputs?
thanks.


also....  i read that the pre2 as the same pre-amp and ADC topology as the 744.  are they the same pre's as the 788 too??
« Last Edit: January 26, 2012, 11:27:15 PM by uncleyug »
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Re: Sound Devices USBPre2 (Part Duex)
« Reply #19 on: January 26, 2012, 11:47:34 PM »
any suggestions on on what input i should use: 
external pre (with unbalanced output) > usbpre2

are the xlr's strictly mic inputs?  or can they be fed a line signal?
is there any difference between the 1/4" LINE and rca AUX inputs?
thanks.

they are designed for a mic-in source; with the 15db pad engaged they clip at +4dbu.

The TRS jacks (which are balanced) clip at +28dbu and the RCAs clip much lower at +9dbu.

What preamp, what's it's max out, and what mics are you using? The theory is if you aren't getting past +10, then it doesn't matter (one will use less line gain, thats it), but if you are, then use the TRS jacks.

also....  i read that the pre2 as the same pre-amp and ADC topology as the 744.  are they the same pre's as the 788 too??

the pre2's preamp stage is more like the 788s than the other 7 series in that it's digitally controlled, but they use the same stuff.
"This is a common practice we have on the bus; debating facts that we could easily find through printed material. It's like, how far is it today? I think it's four hours, and someone else comes in at 11 hours, and well, then we'll... just... talk about it..." - Jeb Puryear

"Nostalgia ain't what it used to be." - Jim Williams

Offline yug du nord

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #20 on: January 27, 2012, 12:11:34 AM »
^vms02ib which has BNC outputs only and has a max gain of +40db...  output clipping begins at 18dbV. 
i use BNC>RCA adapters on the outputs.  thanks G!
« Last Edit: January 27, 2012, 01:27:06 AM by uncleyug »
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Offline bhadella

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #21 on: January 27, 2012, 08:40:42 AM »
^vms02ib which has BNC outputs only and has a max gain of +40db...  output clipping begins at 18dbV. 
i use BNC>RCA adapters on the outputs.  thanks G!

If you are planning on using the majority of the gain from the vms02ib (coming close to clipping at 18 dbu), you need a set of BNC > 1/4 TRS cables and run in via the TRS jacks.  I run full analog gain from my Sonosax ( 20 dbu clipping) into my USBPre 2 via the TRS jacks.  I add 8 dbu of gain via the USBPre 2 (gain knobs at 12:00) to create a full value digital signal to my recorder. 
« Last Edit: January 27, 2012, 08:48:04 AM by bhadella »
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Re: Sound Devices USBPre2 (Part Duex)
« Reply #22 on: January 27, 2012, 09:47:49 AM »
am i correct by saying that 18dbV = 20.2dbu?
or is that incorrect??
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Re: Sound Devices USBPre2 (Part Duex)
« Reply #23 on: January 27, 2012, 10:24:52 AM »
am i correct by saying that 18dbV = 20.2dbu?
or is that incorrect??

that looks right. I did the math last night and came up with something like that.
"This is a common practice we have on the bus; debating facts that we could easily find through printed material. It's like, how far is it today? I think it's four hours, and someone else comes in at 11 hours, and well, then we'll... just... talk about it..." - Jeb Puryear

"Nostalgia ain't what it used to be." - Jim Williams

cashandkerouac

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #24 on: January 27, 2012, 06:01:51 PM »
You need another 2-channel recorder with a digital input (or output). By connecting the USBPre2's digital input to the 722 or any recorder with a digital output, the USBPre2 will sync it's clock with the external source. Then it's just a matter of connecting another deck, like a Sony D50, to the USBPre2's digital output.

It other words, the USBPre2's digital input ignores audio portion of a data stream, but syncs to the sample rate.

Correct. I have a D50 (which is one of the most economical digital in recorders) and I run a spdif cable from aes-id out on the 722 to spdif in on the usbpre2 and set the pre2 to line/mic. Just make sure to turn on the 722 fully before turning on the usbpre2, I've had odd things happen when it trys to sync up different clock sources than when it turned on. There is probably some rhyme and reason to it, but I didn't spend enough time trying to figure it out. SD advises a delayed turn on practice when clocking multiple 7 series units and I don't think it's unreasonable to apply the same standard here.

while you end up with 4 channels using this method, you essentially get 2 synch'd stereo recordings (not 4 separate channels), correct?

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #25 on: January 27, 2012, 08:53:26 PM »
You need another 2-channel recorder with a digital input (or output). By connecting the USBPre2's digital input to the 722 or any recorder with a digital output, the USBPre2 will sync it's clock with the external source. Then it's just a matter of connecting another deck, like a Sony D50, to the USBPre2's digital output.

It other words, the USBPre2's digital input ignores audio portion of a data stream, but syncs to the sample rate.

Correct. I have a D50 (which is one of the most economical digital in recorders) and I run a spdif cable from aes-id out on the 722 to spdif in on the usbpre2 and set the pre2 to line/mic. Just make sure to turn on the 722 fully before turning on the usbpre2, I've had odd things happen when it trys to sync up different clock sources than when it turned on. There is probably some rhyme and reason to it, but I didn't spend enough time trying to figure it out. SD advises a delayed turn on practice when clocking multiple 7 series units and I don't think it's unreasonable to apply the same standard here.

while you end up with 4 channels using this method, you essentially get 2 synch'd stereo recordings (not 4 separate channels), correct?

correct. you can achieve the same on an r-44 depending how you setup the wav file saving. Since I'd have to line up the other two tracks on a 744, I don't gain much other than space by running the dual box setup.
"This is a common practice we have on the bus; debating facts that we could easily find through printed material. It's like, how far is it today? I think it's four hours, and someone else comes in at 11 hours, and well, then we'll... just... talk about it..." - Jeb Puryear

"Nostalgia ain't what it used to be." - Jim Williams

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #26 on: February 07, 2012, 01:26:20 AM »
To anyone that's interested, I asked over at the SD user forum whether limiter/gain linking were planned firmware updates. The answer from Matt at SD was 'No.' Which is a shame.

Ben

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #27 on: February 07, 2012, 09:17:20 AM »
To anyone that's interested, I asked over at the SD user forum whether limiter/gain linking were planned firmware updates. The answer from Matt at SD was 'No.' Which is a shame.

Ben

gain linking would be cool, but I knew they weren't going to do that based on the physical design. There is nothing to tell you that they are linked without flipping it over and looking at the dipswitches.

it's also feature set differentiation. There is only so much they will (or even could) pull from the 7 series features.
"This is a common practice we have on the bus; debating facts that we could easily find through printed material. It's like, how far is it today? I think it's four hours, and someone else comes in at 11 hours, and well, then we'll... just... talk about it..." - Jeb Puryear

"Nostalgia ain't what it used to be." - Jim Williams

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #28 on: February 14, 2012, 04:07:48 PM »
So Win 7 is not seeing my Pre2.   Used to just boot up when I plugged in the cable.  Any ideas what is going on?  Anyone else come across this?

SO I hooked it up while holding in both selection buttons....same thing you can do to force it into preamp mode when hooked up to a computer.  It then installed drivers....weird.  Working fine now. 
« Last Edit: February 14, 2012, 04:17:03 PM by kirkd »

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Re: Sound Devices USBPre2 (Part Duex)
« Reply #29 on: February 22, 2012, 09:42:03 AM »
rockin it as a DAC...  and arffin diggin it!
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