Thinking About Dumping My MOTU Gear...HELP!!

[teknosmoker]

I was thinking about to upgrading to a MOTU HD192, but am having second thoughts...

I'd really like to stay with MOTU gear. I've invested a decent amount into it (2408 core, 1224 expander and PCI-424 upgrade = about $2,000) but I cannot afford anymore down time. My studio has been out of commision all week. If I cannot get this resolved soon, I will probably get an RME PCI card with some decent AD/DA.


Here's the deal --------
I've got a MOTU PCI-424 connected to a 1224 for my analog I/O and an original 2408 (which I've owned since it was released) for all my digital outboard effects. The MOTU system is connected to a dual 2 gig G5 (Early 2005).

I just upgraded my console from a Mackie 32x8 to a high-end Speck XTRAMIX cxi v5 line mixer. I do hardware synth/sampler-based music, don't need mic pre's, wanted to improve my audio signal path and conserve studio space. I also EQ & compress in the box.

Since rearranging my setup (and moving the Mackie out of the studio), something has added a humming noise to my audio signal path (with one bump at 200 Hz and another one at around 400 Hz). I'm using all balanced cables and have stripped everything away except for the MOTU stuff, the computer and the mixer (no other gear connected to the mixer or plugged into a power source). I've also ensured that everything is plugged into the same electrical outlet in the studio. Aside from studio gear, the only other electrical device in the room is an incandescent lamp.

Even with the headphone volume turned all the way down on the Speck mixer, I get the hum when the 1224 and G5 are both powered up. The hum begins as soon as I have video on my Apple Studio Display 17" LCD (connected via an Apple DVI to ADC adapter). If I switch the 1224 off (with the computer still on) the hum goes away. As soon as I turn it back on, the hum returns.

I tried moving the PCI-424 card from the bottom to the top PCI slot (other PCI slots contain a UAD-1 and an Adaptec SCSI card). I've taken the MOTU 1224 out of the rack and moved it around the studio, while listening through my headphones. When it's near other gear or the coiled balanced cables connected to the 1224's I/O, it hums even louder.

I disconnected the Speck mixer and tried running the signal through the Mackie 32x8 to see if the Speck had introduced the problem, but still got the same humming through the Mackie (accompanied by the noisy hiss of the Mackie). I tried swapping out cables, still no luck.

I listened to some of my recent sessions (before this problem began) and did not notice any of the above mentioned noise during silent passages of my recordings.

I'm going to borrow a friend's Presonus Firebox tomorrow, in an attempt to narrow the problem down to the MOTU gear.

BTW - the 2408's analog section now hums too.

Does anyone have any ideas/suggestions? I've almost run out of things to try.....

[James Steele]

I was thinking about to upgrading to a MOTU HD192, but am having second thoughts...

I'd really like to stay with MOTU gear. I've invested a decent amount into it (2408 core, 1224 expander and PCI-424 upgrade = about $2,000) but I cannot afford anymore down time. My studio has been out of commision all week. If I cannot get this resolved soon, I will probably get an RME PCI card with some decent AD/DA.


Here's the deal --------
I've got a MOTU PCI-424 connected to a 1224 for my analog I/O and an original 2408 (which I've owned since it was released) for all my digital outboard effects. The MOTU system is connected to a dual 2 gig G5 (Early 2005).

I just upgraded my console from a Mackie 32x8 to a high-end Speck XTRAMIX cxi v5 line mixer. I do hardware synth/sampler-based music, don't need mic pre's, wanted to improve my audio signal path and conserve studio space. I also EQ & compress in the box.

Since rearranging my setup (and moving the Mackie out of the studio), something has added a humming noise to my audio signal path (with one bump at 200 Hz and another one at around 400 Hz). I'm using all balanced cables and have stripped everything away except for the MOTU stuff, the computer and the mixer (no other gear connected to the mixer or plugged into a power source). I've also ensured that everything is plugged into the same electrical outlet in the studio. Aside from studio gear, the only other electrical device in the room is an incandescent lamp.

Even with the headphone volume turned all the way down on the Speck mixer, I get the hum when the 1224 and G5 are both powered up. The hum begins as soon as I have video on my Apple Studio Display 17" LCD (connected via an Apple DVI to ADC adapter). If I switch the 1224 off (with the computer still on) the hum goes away. As soon as I turn it back on, the hum returns.

I tried moving the PCI-424 card from the bottom to the top PCI slot (other PCI slots contain a UAD-1 and an Adaptec SCSI card). I've taken the MOTU 1224 out of the rack and moved it around the studio, while listening through my headphones. When it's near other gear or the coiled balanced cables connected to the 1224's I/O, it hums even louder.

I disconnected the Speck mixer and tried running the signal through the Mackie 32x8 to see if the Speck had introduced the problem, but still got the same humming through the Mackie (accompanied by the noisy hiss of the Mackie). I tried swapping out cables, still no luck.

I listened to some of my recent sessions (before this problem began) and did not notice any of the above mentioned noise during silent passages of my recordings.

I'm going to borrow a friend's Presonus Firebox tomorrow, in an attempt to narrow the problem down to the MOTU gear.

BTW - the 2408's analog section now hums too.

Does anyone have any ideas/suggestions? I've almost run out of things to try.....

I don't mean to cast aspersions on the Speck mixer, but unless I'm reading something the wrong way in your post, both your 1224 and 2408 were okay when connected to the Mackie, then when you brought home the Speck and hooked it to that, both MOTU interfaces decided to start humming at the same time?

I have a HD192, 24I/O and a 1224 like you and don't have issues like this with my 1224. As you said, no hum from units with Mackie. Looks like the only thing new in this is the Speck. Can you borrow another small mixer? Maybe it's cabling to the Speck or a grounding issue. Trying using a ground lift on the Speck just to see. Perhaps you just got a Speck that has a defect maybe? Honestly the fact that there is hum in the analog output of BOTH interfaces seems odd. If MOTU interfaces all acted like you describe, nobody would buy them at all.

Is this hum happening when you crank the monitors up ungodly loud? Again, I'm suggesting that if your setup has the same gear it had before and all you did was switch mixers, it doesn't seem logical to blame the interfaces.

[teknosmoker]

Thanks for the reply.

I know that the swapping of the mixers should not have had any affect on my MOTU gear - that's what makes the situation so odd.
I disconnected the Speck, removing it completely from both power and audio path, and reconnected the 1224/2408 to the Mackie (sorry if my post wasn't to clear). The hum/noise is still present with the Mackie as well.

1224 main outs going to effects returns and 2 Mackie subgroup outs going to 1224 inputs 1 and 2.

It does seem very coincidental that the problem began once the studio was rearranged. I first assumed that the Speck was the culprit, but I've returned the configuration to how it had been before and am still experiencing the same problem...Perhaps the jostling of reconfiguring the studio killed something?
Possibly the PCI-424 card?

[James Steele]

Thanks for the reply.

I know that the swapping of the mixers should not have had any affect on my MOTU gear - that's what makes the situation so odd.
I disconnected the Speck, removing it completely from both power and audio path, and reconnected the 1224/2408 to the Mackie (sorry if my post wasn't to clear). The hum/noise is still present with the Mackie as well.

Oh... whoops. Thanks for mentioning that. That truly is bizarre then. It sure sounds like a ground loop doesn't it? Did you move your computer around? You could try re-seating the card. It's a 424 card right? Maybe check to see if Cue Mix doesn't have channels opened up and is adding additional gain. (hmmm... maybe not... shooting in the dark).

1224 main outs going to effects returns and 2 Mackie subgroup outs going to 1224 inputs 1 and 2.

And they're level matched right? 1224 main outs are +4db on XLR aren't they? Your effects returns are cool with that? What happens if you bring your main outs of the 1224 into a pair of regular input channels? Same thing?

It does seem very coincidental that the problem began once the studio was rearranged. I first assumed that the Speck was the culprit, but I've returned the configuration to how it had been before and am still experiencing the same problem...Perhaps the jostling of reconfiguring the studio killed something?
Possibly the PCI-424 card?

Geez... dunno... that's a good guess, because it's odd that the 2408 and 1224 both started doing that. I guess I check if it has anything to do with chassis touching. Are audiowire cables seated well. I was going to ask if they're running close to power cords, but they carry digital info, not analog so that wouldn't be it. It would be cool if you could get another card to see if the problem goes away.

I guess you could also get up early and calll MOTU tech support and they might know something. Hope someone hear can help you figure it out. It does sound like it's not MOTU interfaces are generally bad, since they were okay before and now it's happening with the Mackie when it didn't before. And doubtful BOTH interfaces went bad at once. Again, maybe open up the computer... re-seat the card or perhaps even try a different slot?

[emulatorloo]

It sounds like a ground loop got introduced somehow when you rearranged your studio.

Some pretty good ideas here:

Ground loop problems and how to get rid of them

http://www.epanorama.net/documents/groundloop/

--

[weez]

I had the same thing going on and in my case it was as simple as one of my MIDI cable to a sound module was the culprit.

[teknosmoker]

Thanks for the replies everyone. Troubleshooting grounding/noise issues can truly be maddening!
BTW - Great link for ground-loop issues emulatorloo!

I tried swapping the MOTU with a friend's Presonus Firebox (using the identical audio and power connections as I did with the 1224) and got no hum.

The transformer inside my 1224 often sounds like a lawnmower. I took the lid off the chassis and found that there were a few pieces of paper laying around inside the unit! Each looks to have been a model number sticker that was once attached to internal components (about 2 cm x 2.5 cm.), with dates stamped on each. It seems that they had dried out and were just bouncing around inside the unit. I also tightened some connections within the 1224 and put it back in the rack.

After rearranging the setup again last night, the 1224 was almost silent when monitoring through headphones. I had reconnected everything except my monitors (HR824 - the older American-made grounded ones). As soon as the monitors were reconnected the hum returned. When the 1224, the computer/display and monitors were connected, the hum remained. As a temporary workaround, I've connected the HR824s without the electrical ground (hm, could that have anything to do with why the current production models ones don't have an electrical ground?).

BTW - Before I had the Speck, I was using a Mackie 32x8 as a line mixer for monitoring. With all pre's/trims, faders, busses, returns down - only the master fader at unity gain, the Mackie emits MUCH more hiss than the XTRAMIX, which is practically dead silent. I guess the low level hum that the 1224 had been generating before was covered up by the hiss. The XTRAMIX sounds amazing. The sonic difference & headroom between it and the Mackie 23x8 are truly night and day!

For now I'm going to stick with the 1224, but would really like to improve my A/D/A. I'm not sure if I want to go with an HD192 or perhaps a nice high-end multi-channel convertor plugged into one of the ADAT jacks on the 2408. I'm currently only using the 1 of the ADAT pairs & the SPDIF I/O on the 2408.

Cheers,
T

[teknosmoker]

@James Steele

Thanks for the suggestions!

-First thing I tried was moving the computer around and swapping PCI slots for the 424 card.
-Everything is turned off in the Cue Mix console (I never really use it).



Still can't decide on whether to upgrade from the 1224 to an HD192 or whether it'd be better to get some nice 3rd party A/D/A conversion (4 to 8 channels, going both ways) via the ADAT connection of my 2408. Has anyone had experience with using good alternate means conversion, connected via their 2408?

Not sure if it matters, but I have the first 2408 with the RCA analog/I/O (but I do have a PCI-424 to go with it).