Unexpectedly low volume playback - could it be the adapters?

[WayStar]

Hi all-

This is only marginally if at all a Fostex question, but any input is appreciated.

I've got a Fostex D2424LV (two actually) and I am totally in love with them for recording or playback into my DAV via the optical cable.

My problem is in the other room, where I run the recordings which play in our planetarium theater.

Most of our stuff is still on the 1/2" 8-track tapes, played back via an Otari MX5050. The Otari doesn't have long to live, and neither do the tapes, so going digital is a real necessity for us.

We have a snake which goes from the Otari (via XLR connectors) to the system (mixers, etc). Because of the way it's all put together, the practical thing to do is use the same snake. This means adding adapters to get from XLR to 1/4". Once all of our material is converted, we can solder new connectors onto the snake, but in the meantime, we need to be able to switch between playback units.


Moving the snake to the Fostex works just fine, but the volume is far lower than that of the Otari. This is with stuff recorded on the Fostex as hot as we can get it without yuckiness, too.

Although there's no way to make all things equal, I've come to suspect the adapters we're attaching to the snake. I'd love to simply bypass the snake and go directly from the Fostex to that next stop in the chain, but we have some confusion as to where that next step is located.

So ultimately, my questions are these:

*How can I quantitatively measure the output of this unit with and without adapters? I'm a bit of a newbie (okay, a lot of a newbie) in serious audio troubleshooting.

*If indeed the adapters are my problem, is there a way I can boost the output to counter that depletion in signal strength?

*If the adapters are not the problem, where should I look?

Any input is greatly appreciated. Thanks.
-Waylena

 

[Ginzoo]

Are you able to mix this down to 2 tracks permanently or do you need to keep it 8 tracks for perfomance reasons ?
My first thought was to get a great mix...run it from tape to mixer down to your main outs and into the fostex. Just a thought...

 

[skippy]

The outputs should be selectable to output either unbalanced at -10dBV, or balanced at +4dBu. If you have the thing set for -10dBV, and the Otari is outputting an honest +4, there's your difference...

I haven't played with the 2424, but I think that you should be able to find something like maybe "output reference level" in the setup page. Sounds to me like you're pushing low-level, single-ended into a rig that wants the higher level, differential signal- there's 12dB or more right there.

I just checked the D2424 manual on the Fostex web site, and that is definitely the problem. It says: "Analog input/ouput ports are set to 'unbalanced input/output' in the initial state. These can be changed to 'balanced input/output' by the BAL/UNBAL SETUP menu in the Setup mode..."

Go into setup, and fish around for this screen. Set it to balanced, and you'll get the level you need!

 

[WayStar]

SUCCESS!!

2 things at work here.

Last night, before leaving, I made some cables to go from the Fostex to the mixers. Not pretty, but they work. That boosted it quite a bit, and improved the clarity of the sound.

This morning, I found your responses and decided to try changing the setting to balanced. I was pretty sure that down the line things end up going to unbalanced, so I'd left it set that way originally. Now that I think about it, however, keeping it balanced until it's first destination beyond the sound room is a good thing.

In any case, the change also improved the sound, such that it's now almost up to where the Otari was. (I don't expect it to be totally up there, given the difference in range and the fact that a lot of our shows have rocket launches -very noisy- that were left to be distorted with the Otari. With analog, distortion in the rocket launch added to the ambience. With digital, it sounds pretty mean and ugly.)

And there was much rejoicing! Thank you!!!

As for the mixes themselves, we only use 3-5 tracks for out theater. It may seem like overkill to use something that can handle 24, but I see it as just leaving more room on the disk. In fact, after our first weekend of using the new setup, I'm going to reformat the drives to 16 bit. I made the default 24 bit, but none of our sources are 24 and our sound system itself introduces just enough noise to outweigh any potential benefits.

Tracks one and two are left and right audio, which also gets sent to front and back, with a piece of a center cluster shared between them. Tracks three and four are center only, seldom used in regular programs, used mostly for audio coming off of a video source. (For example, a person talking on video will use the audio from the video source, rather than try to sync the main playback.)

Fortunately, we've got a kick-butt automation system that lets us program when these things will start, stop, roll over, or play dead. If only I could program them to get me my coffee...


Thanks again for the help, you guys rock!

-Waylena