Topic: Sound Devices USBPre 2

[WiFiJeff]

I was told that the manual is not a "misprint" but rather refers to an earlier version of the final build.

When a similar issue arose with the Core Sound Mic 2496 version 2, they had to replace a chip.  Not sure how the SD USBPre 2 will handle any upgrade.

Good news: I foolishly took the USBPre 2 along today and substituted it for my V3 to feed (digitally) an R44, without testing how the R44 took the signal.  It seems to have recorded correctly, no issues I can see.

Jeff

[NicStage]

The graphic in the DIP Switch section of the manual was incorrect. I uploaded a corrected version yesterday afternoon.

[NicStage]

So we have this narrowed down and we're pretty confident we have a solution. Some devices determine sample rate by actually measuring the rate of incoming samples (7-Series, USBPre, etc) and other devices determine sample rate by reading embedded data in the S/PDIF stream (DR-680, PCM-D50, etc). The USBPre 2 wasn't sending out this embedded data. I just got done testing a beta version of firmware for the USBPre 2 that behaves properly with the PCM-D50 (i.e. the PCM-D50 in record-pause will show the proper sample rate and bit depth of signal being fed from the USBPre 2). We will be releasing this firmware once it finishes our standard round of testing.

[kirk97132]

You da man!  Can't wait to hear the results of your testing

[MichaelPatrick]

Nic, thanks for taking the time to not only explain but post pictures for (me) us.  And I agree, your input and you feedback here are great.  It's a tangible selling point for me that a manufacturer is not just responding but implementing ideas garnered from the discussions.   You set the bar pretty high for other people who would follow your lead.  I cannot wait to get delivery of the pre. 

So gang, while I was originally going to use a voltage regulator on one of my 9V dvd batteries, I am thinking of going another direction.  Mostly because I am looking for a 12V source for my Apogee AD1K.  I leaning towards the battery on flea bay that has 5v, 9V, &12V outputs.  There's been some ok feedback from buyers.   I still might make a 5V step down too since the parts are so cheap.  How are you guys figuring on powering the unit in the field?

This battery sells for about $70 at Amazon and other internet dealers. http://www.lenmar.com/web/ProductDetails.aspx?ProductID=PPU916

[bhadella]

I was able to test my USBPre 2 with another R44 and sucess!   No problems locking onto a 24/48 signal from it.   Bad news, my R44 has a bad coax in.   Looks like I need it serviced.  Paging Busmann. 

[kirk97132]

UPDATE:  Sound Devices should be announcing the fix soon to solve the digital issues discussed here.  I'm sure Nic will post a link as soon as it is ready.  It is a real easy firmware update. 

I want to get out as soon as I can to run this in the field.  I did some real basic battery test using the Voltage regulator box I built.  So far so good.  I ran the 680 and the USBPre2 off the same battery for about an hour and a half and it dropped one light on the dvd battery, that was a battery that had been sitting for awhile.  It showed a full charge to start.  I'll do a better test and report back.  After running it that long the box was not even warm, so there are no heat issues to report. 

Once I get to use it I'm gonna run it digi in and analog in just to see how, if any, the 680 flavors the sound. 

[snailed]

hi all, first post here, so i apologize for the newbie question...

what is the best way to properly power this for field use?  not looking to power any other devices - i'd be looking to just power the USBPre 2 to go into a Zoom H2 or possibly a Microtrack.  I want to use the USBPre 2 as a field mixer and preamp to go into one of those recorders.  Will the simple AA battery powered USB chargers that are sold on ebay on the cheap actually provide enough power?  Are there any advantages to buying a more expensive battery solution?  Does anyone have any recommendations that will definitely work for this unit? 

thanks, and I know a lot of this has been covered in the thread already - I just want to be totally clear on this before I put down the money for a USBPre 2 (unfortunately I don't know much about putting together my own power supply like Kirk has done).

[kirk97132]

The USBPre2 power requirements(page 19 of the manual):
5 V (+/- 10%), 500 mA .  Anything that supplies that via a usb plug will work.   I'd be happy to make you a setup to work with the 9 volt dvd batteries if you wanted.  Just send me a pm and we'll talk. 

[sunjan]

Will the simple AA battery powered USB chargers that are sold on ebay on the cheap actually provide enough power?  Are there any advantages to buying a more expensive battery solution?

1. More mAh = longer running time between recharges. Of course AA battery sleds will work, but it remains to be tested how long running time you'll get with 4 or 8 NiMH batteries. If your need is only 3-4 hours, you should hopefully be fine, as long as you use high quality AA's.
2. Li-based battery chemistry has higher energy density, meaning you'd carry less weight equivalent for the same running time.

[WiFiJeff]

The tiny (under 5oz) Cinch Power CP505 (lithium) I tried out is rated at 5000 mAh at 3.7V (why do they use 3.7V when they are 5V devices, is there some standard I am unaware of here?), I got over 6 hours before I shut it down and two of the three lights were still on.  This was using Nevaton mics, rated are at the USBPre 2 max draw of 10 mA each.  This battery will put out up to 950 mA, but assuming it is feeding the USBPre no more than 500 mA I should get at least 7.4 hours (right?).

Jeff

[kirk97132]

The 3.7 volt rating is ear outside the printed parameters which on the low side would be 4.5 volts.  Not to say it won't work.  We as tapers run many devices below the printed power requirements.  The 680 and HD-P2 are perfect examples.  Both rated at 12volts yet work perfectly at 9 volts.  Have you recorded anything with it yet?  How does it sound?  Maybe Nic could check with the engineers to see what if anything is affected by using lower power into the deck?  OR maybe a phone call to SD?  I wonder what it actually supplies at the mics for phantom if you only supply it with 3.7 volts.  Does that drop your phantom voltage too?

[WiFiJeff]

I think you misunderstood my post.  The battery is rated "Output 5V 950 mA" and it runs the USBPre 2 fine, I recorded to a Sonosax MiniR82 digital-in.  But the battery also says on it  "Capacity: 5000 mA at 3.7V" and I was asking why the capacity is measured at 3.7V when the output seems to be at 5V.  Why not a capacity rating like 3700 mA at 5V, which would be the same power capacity?

Jeff

[Todd R]

As I understand it, the Cinch CP505 puts out 5v.  I think what WifiJeff was referring to is that Cinch lists it at 5000mA-hr at 3.7v.  This is probably because it uses a 5000mA-hr, 3.7v li-ion battery internally, then steps the voltage up to 5v.

As to how long it will last, 5000mAhr @ 3.7v = 18500 mW-hr capacity, divide then by 5v = 3700mA-hr at 5v.  But this is assuming a 100% efficient step up from 3.7v to 5v.  Assuming that is more like 85% efficient, leaves you 3145mA-hr at 5v, so about 6.3 hours of runtime at a 500mA draw.

The 500mA draw is the max draw though, not average.  Who knows what that is -- maybe 425mA as a total guess?  That might mean more like 7.5 hours of runtime.

[Todd R]

Sorry Jeff, you were posting when I was typing.

Why not 3700mAhr at 5v, rather than the 5000mAhr at 3.7v they state?  Marketing hype.  I'd guess it gets back to the actual size of the internal battery used in the CP505.