Topic: Attenuators for SBD>AD-20>JB3

[drowned_in_milk]

OK I've read the other SBD>AD-20>JB3 topic but it mentions nothing of what type of attenuators I'd need.  I refuse to spend the extra money on a HOSA box when the AD-20 will convert XLR>Optical for me, I just need to know what type of attenuators to keep the signal from getting too hot.  Are there any switchable attenuators that I can switch different levels?

[ashevillain]

I refuse to spend the extra money on a HOSA box when the AD-20 will convert XLR>Optical for me,

The HOSA converter is really a non issue for you in this case anyway...

You basically have 2 options:

1. Line-In to the JB3 and forget the AD-20 for SBD patches. Let the JB3 do the A/D conversion. (preferred)

2. Get a set of attenuators. Here's a couple of examples of switchable attenuators->
http://www.micsupply.com/shureatten.htm
The problem with this is that the AD-20 gives a minimum of +17dB of gain at it's lowest setting. If you used this attenuator at it's max setting of -25dB that still only gives you an +-8dB window in with which to work. If you can have the sound person adjust the SBD's output then that may help a bit. Still though, you are adding gain(SBD) > attenuating > then adding more gain(AD-20)...to me this adds noise which is undesirable. If you're dead set on using the AD-20 in this chain, then I would use at least 30dB of attenuation just to give myself some room for error.

I believe this is the one Moke speaks of -> http://www.bhphotovideo.com/product/68085/AUAT8202/REG/2487
here's some more -> http://www.bhphotovideo.com/links/2487.html

hope this helps
cliff

edited for links

[Brian Skalinder]

As Cliff said, the Hosa box is irrelevant.  It merely converts one digital format to a different digital format.  You want to convert analog to digital, so you need use your AD20 or the NJB3's internal ADC, neither of which requires the Hosa box.

Check the Archival Info forum for attenuator part numbers.

[wsphansam]

 You'd be good to go I think if you got the AT8202 attenuators. I use them w/ my AD-20 and JB3. They provide switchable -10,-20, and -30dB, not a max of -25dB as said above. If you had those set at -30dB and the gain down on the AD-20 I think you'd be set, keep in mind though I have never done a sbd patch with this setup however.

[ashevillain]

They provide switchable -10,-20, and -30dB, not a max of -25dB as said above. If you had those set at -30dB and the gain down on the AD-20

I was referring to the Shure attenuators with this statement. I added the other links later and didn't re-proofread my post...so yeah...sorry for the confusion!

Even w/30dB of attenuation that's still only giving you, at best, a 13dB window to work with...that's cutting it a little close for something you've never done before...even closer if the SBD is sending a 'hot' signal and/or the sound person cannot adjust the output. The JB3 A/D does not sound bad...

:2cents:

[drowned_in_milk]

You basically have 2 options:

1. Line-In to the JB3 and forget the AD-20 for SBD patches. Let the JB3 do the A/D conversion. (preferred)

From what I've read the internal AD picks up the sound of the hard drive spinning, putting a faint whirring sound on the recording... which is discouraging me from ever using the JB3 line-in...

[Brian Skalinder]

From what I've read the internal AD picks up the sound of the hard drive spinning, putting a faint whirring sound on the recording... which is discouraging me from ever using the JB3 line-in...

I haven't tried this myself as I always run digi-in to my NJB3, but others - including David Klein, I believe - indicate the hard drive noise is only an issue running mic-in, not line-ine.

[John Kelly]

You basically have 2 options:

1. Line-In to the JB3 and forget the AD-20 for SBD patches. Let the JB3 do the A/D conversion. (preferred)

From what I've read the internal AD picks up the sound of the hard drive spinning, putting a faint whirring sound on the recording... which is discouraging me from ever using the JB3 line-in...

It doesn't.  Unless, as Brian said, you're running mic in, which you shouldn't be doing from a SBD feed.

[themonkey]

I've been wondering about this setup myself as i also have an ad-20 and jb3.  I patched a few times off of boards and from other Dat recorders.  For my ears, i haven't noticed any signficant noise using the line in.

Besides some of the other good points made, the setup good be a bit cumbersome to set up as well. 

[dklein]

The JB3 hard drive noise is there for mic-in or line-in - it's just that mic-in has such severe high frequency rolloff that it's unacceptable for music (but ok for voice).

The hard drive noise peaks at -73 dB when using line-in, gain 0 dB.  It peaks at about -62 dB when using line-in, gain +12 dB, so you can't use the analog gain in the JB3 to 'boost around it'.  BUT, -73dB is really far back there.  I looked at a couple of audience recordings I did and even the quietest moments between songs have average levels of -50dB and peaks of -30, so this is well below the noise floor.  Bottom line - if you are getting adequate levels on the JB3 meters, you will never hear the hard drive noise.  The reason lots of people are hearing it is because the average microphones can't properly drive a line level input and they end up using tons of amplitude boost in software to bring the levels up (along with the hard drive noise).  I have a show where the noise is bothersome during quiet passages, but I had to use +12 dB while recording and +23dB in post...that's a lot of gain!

So if you're getting a feed from a soundboard, there won't be any issue getting adequate levels - I'd use a direct connection to the JB3 rather than the combo of boost-cut-boost (board>attenuators>AD20>JB3).  And the JB3 gives you a 24dB analog window on the line-in.

[dklein]

here's a link to a link for a sample of that show I referred to above here