Presonus Digimax FS Problems

[ghr]

About two months ago I purchased a Digimax FS from ebay, advertised as brand new in box. Sure enough, when it came all looked well and brand new so I put it under my bed since I've been busy with University work.

Today I decided to give it a go, so I powered it up, linked the direct out of the channel into one of my RME Multiface TRS inputs, plugged in the mic... nothing. Turned the gain all the way up, and all that is audiable is a feint "pop.. pop.. pop.." sound.

I thought that this may be to do with clocking - but I can't imagine such a unit needs wordclock or ADAT sync to use the analogue outputs of the unit? I don't have any BNC or ADAT cables at the moment, so haven't been able to check whether this helps.

I tried my trusty Behringer cable tester in test tone mode, and the same noise was there. I decided to try try channel two just incase it was a dead channel. BEEEEEP. Yep, it works. Moved along to number three... "pop.. pop.. pop".. okay... number four.. again, test tone comes through.

Tried all channels - the "even" numbered channels work fine - the "odd" numbered channels have the "pop pop pop" sound!!

Anyone have ANY idea on whats going on?!

Thanks
Gareth

[Guest]

Curious.

Tried calling Presonus tech support?

[Hugh Robjohns]

I thought that this may be to do with clocking - but I can't imagine such a unit needs wordclock or ADAT sync to use the analogue outputs of the unit?

The handbook states: "In any scenario, your system must be synchronized in order to perform properly. Poor synchronization, or an oversight in synchronization settings, is the most common cause of clicks, pops, and other anomalies in the digital studio environment."

I agree, that doesn't seem logical if the Direct uotputs really are direct outputs, but it's what it says int he book.

The scenario where only half the channels works does sound like a clocking issue of some sort. It's hard to see why every other analogue direct out is affected... I guess the most likely things is a power supply issue.

If that's not the case, I'd hazard a guess that the SMUX mode is on and it's trying to run at 96kHz or something like that.

Probably best to go back to basics on this one.

Are you sure you're plugged in to the direct outs and not the DAC outs or insert points instead -- it would be an easy mistake to make if you're leaning over the back...

And if you are using the direct outs, are you sure you're following the correct numbering sequence? Again, another easy mistake to make.

If you're sure you're using the correct direct outs, then the next step would be to test the internal A-D converters via the ADAT outputs, to see if that stage of the signal path is working.

But if none of that helps, Presonus tech support is your best bet.

Hugh

[ghr]

Thanks for the replies guys.

It is an odd problem, and I myself was surprised by that quote in the manual, especially since either the website or manual (forgot which!) says the direct outs are pre ADAT conversion.

I did think about it being some odd SMUX thing too, but the unit was set at 44.1kHz on internal clock, so shouldn't be?

Yup, plugged in to direct outs and used just one TRS cable and moved it between the outputs as neccessary. Interestinly (but not welcomed) there also appeared to be a little crosstalk between channels. With the signal generator going in to pre-amp one and the TRS plugged in to direct out two there was a feint beep - but I'm thinking this is due to whatever "damage" my unit has.

I don't have any ADAT nor BNC cables to hand, so I'll have to wait until I can get my hands on some.

Rick from Presonus spotted my post on a different board and mentioned it may be shipping damage, and sounded like a power supply issue so you may be on to something there Hugh!

I've emailed him directly, so I'll let you know what he suggests.

Thanks for the help
Gareth

[Hugh Robjohns]

It is an odd problem, and I myself was surprised by that quote in the manual, especially since either the website or manual (forgot which!) says the direct outs are pre ADAT conversion.

Yes, it's not likely to be the problem, but if the unit's functions are controlled in some way by a machine controller chip, a lack of clock could cause all sort s of problems. Don't think that's the case here, but you never know and it's always worth setting the unit up as intended before assuming it is broken!

Rick from Presonus spotted my post on a different board and mentioned it may be shipping damage, and sounded like a power supply issue so you may be on to something there Hugh!

It's entirely possible -- quite likely, even -- that the board layout splits even and odd preamps, and that they are supplied by power from different regulators. So a failure of one regulator could take out multiple preamps.

But this is board level maintenance stuff, and I don't have the technical manuals to hand so it's purely guess work.

Nice to know Presonus are so responsive though. Hope it gets fixed soon. It's usually very reliable kit.

Hugh