DL1608 destroying my Mac Mini(s)

[RoadRanger]

Can't actually remember (old age) are the combo jacks on the DL1608 phantom enabled? I've been doing what you do connecting laptops/iPads/pods to 15/16 on the DL for a while and no issues ever. And I've had to run with phantom enabled while doing this.  I do use a dual DI box and mic cables for long runs though, always. This is the DI I use:
https://www.long-mcquade.com/840/Pro_Audio_Recording/Mic_Preamps_DI_Boxes/ART_Pro_Audio/Dual_Passive_Direct_Box.htm

When a mixer has both XLR and TRS inputs on the same channel, I've never seen a TRS jack that has phantom - the DL1608 certainly doesn't.

I always carry a bunch of 1 foot XLRF to TRS and XLRM to TRS cables so I can plug line level XLRs into the TRS line inputs anyways. That saves deploying a LOT of DI's - it's not uncommon to use up the four TRS inputs with a couple stereo keyboards and/or the XLR output from a bass amp.

It's unfortunate that the DL1608 doesn't have TRS inputs on all channels - or at least would let you route the 13-16 inputs to any channel strip you want so you could properly arrange the channels to your liking. I believe the X-Air has both of those things? I'm really hoping Mackie will have time to play a bit of catchup with the feature set of the X-Air soon - many things are doable with the present hardware and already in MF for the DL32R but disabled when a DL1608 is connected .

[WK154]

The DI box you're using as most others block 48V phantom power. The 48V + is on XLR 2,3 with the shield as the return pin 1. TS or TRS connectors can be used on inputs 13 - 16 on the DL. There is no 48V on any TS/ TRS connectors. For the stereo 3.5 mm T & R are the two signals with a common return S. They are unbalanced signals. TRS/TS inputs also have a 20 dB pad to accommodate line inputs.

[ILC Saratoga]

I've just reread the start of this thread and the OP ILC Saratoga says he connects the headphone output to CH16 XLR input. There are several ways to do this, nearly all wrong (even some which employ a DI box). I'd be interested to know precisely what type of lead/adapter was used?

The cabling is 1/8" Stereo to XLR adapter with XLR to XLR. All cabling is from Monoprice.   All internal wiring is correct i.e. no shorts or unintentional grounding, infact this worked for 4 MONTHS then POOF.  I'm thinking the isolation transformer mentioned above might be the correct answer.  But the $64k questions is WHY after 4 months?  I'm going to give Mackie Tech a jingle and see if there is some secret button somewhere.

I sincerely appreciate all of the replies.

[ILC Saratoga]

The DI box you're using as most others block 48V phantom power. The 48V + is on XLR 2,3 with the shield as the return pin 1. TS or TRS connectors can be used on inputs 13 - 16 on the DL. There is no 48V on any TS/ TRS connectors. For the stereo 3.5 mm T & R are the two signals with a common return S. They are unbalanced signals. TRS/TS inputs also have a 20 dB pad to accommodate line inputs.

Can you translate that for a volunteer that is doing the audio that doesn't know diddly?    I'm assuming that inserting the appropriate box in-between eliminates the phantom power.

[Keyboard Magic]

RoadRanger and WK;

Thank you both for your help and answers. I really appreciate it. The beauty of analog mixers like my ZEDD, has dedicated stereo 1/4 in and RCA. This makes it very simple to connect most stereo devices, like keyboards, consumer audio, without eating up channels which can be used for mics. As in the ZEDD, 4 XLR and 2 stereo pairs. I guess to save money by adding separate stereo pairs Mackie went with XLR and combo jacks. Which I have made do with for sometime, very happily.

[WK154]

I've just reread the start of this thread and the OP ILC Saratoga says he connects the headphone output to CH16 XLR input. There are several ways to do this, nearly all wrong (even some which employ a DI box). I'd be interested to know precisely what type of lead/adapter was used?

The cabling is 1/8" Stereo to XLR adapter with XLR to XLR. All cabling is from Monoprice.   All internal wiring is correct i.e. no shorts or unintentional grounding, infact this worked for 4 MONTHS then POOF.  I'm thinking the isolation transformer mentioned above might be the correct answer.  But the $64k questions is WHY after 4 months?  I'm going to give Mackie Tech a jingle and see if there is some secret button somewhere.

I sincerely appreciate all of the replies.

The secret button is called phantom power. With your incorrect cabling you've applied 48V to an output (iPad/Mac mini) and it took 4 month to die. Yes the DI box will stop this problem when inserted between the iPad/Mac Mini and the DL. Please send me the $64K.

[Keyboard Magic]

The DI box you're using as most others block 48V phantom power. The 48V + is on XLR 2,3 with the shield as the return pin 1. TS or TRS connectors can be used on inputs 13 - 16 on the DL. There is no 48V on any TS/ TRS connectors. For the stereo 3.5 mm T & R are the two signals with a common return S. They are unbalanced signals. TRS/TS inputs also have a 20 dB pad to accommodate line inputs.

Can you translate that for a volunteer that is doing the audio that doesn't know diddly?    I'm assuming that inserting the appropriate box in-between eliminates the phantom power.

Exactly! It stops the phantom power (up to 48 volts direct current ) from getting to your laptop, media player etc and balances the signal to eliminate any noise from said devices so no one can hear it in the audience, especially you. If you've ever connected an old ghetto blaster to your system and gotten a very annoying hum through your speakers a direct box will usually stop that.

That's my take on it. Some of the more learned here will be able to explain it better.

[sam.spoons]

We are also ignoring the stereo/balanced issue here too (WK and RR touched on it), a simple TRS-mini to XLR would not only put 48VDC between tip and sleeve and between ring and sleeve of the headphone output but would also sum the left and right channels to mono but with opposite polarity. Very strange that it should have worked at all.

Assuming you can spare two inputs for the Mac Mini, I would use a TRS-mini (headphone jack) to 2 x TS ¼" jacks and use two TRS input channels. This will be safe from phantom power. For recording use two aux outputs with a similar lead (not the ideal way to unbalance the outputs but it should work) into the audio line in on the mini not a single TRS-¼" > TRS-mini lead.

[pytchley]

The secret button is called phantom power. With your incorrect cabling you've applied 48V to an output (iPad/Mac mini) and it took 4 month to die. Yes the DI box will stop this problem when inserted between the iPad/Mac Mini and the DL. Please send me the $64K.

Or an inline isolation transformer. I use these http://whirlwindusa.com/catalog/black-boxes-effects-and-dis/transformers-isolation-devices/isoxl and the only B********r product I endorse! http://www.behringer.com/EN/Products/HD400.aspx Stops the 48v and cancels all sorts of annoying hums into the bargain. Cheaper and smaller than a Di if you don't otherwise need it.

[Greg C.]

On a Mac that is true.  The Mac audio output is DESIGNED to put out amplifier level to headphones, Line level to amps and even light for fiber cable. (Surround Sound digital on the fiber.)  DESIGNED for all that. (And on mine, also a microphone input in the same connector.)   I'm not interested in suggested off product uses.  I don't use Microphones as speakers or speakers as microphones.  (And dynamic microphone parts are the same type of parts as speakers have.  Coil, Magnet and diaphragm.)

Your assessment of headphone output capabilities demonstrates a lack of understanding of impedances in relation to driver circuits vs. loads. Headphone outputs and "line outputs" operate in similar voltage ranges. The main difference between the two is electrical current delivery capability. In theory, a headphone output is capable of delivering more current than a line level output in order to drive the relatively low impedance load of a headphone speaker without overheating the driver circuit and/or causing distortion. Using that same circuit to drive a line input which is relatively high impedance is a non-issue. You will not "burn out" the input because you're only sourcing a minuscule amount of current which is the identical amount of current you'd be getting from a dedicated "line level" output. The input will only source as much current as it's high impedance will allow, not what the output circuit can supply. As I said previously, the voltages are going to be similar.

The converse though doesn't always work out. You really shouldn't use a line output to drive a low impedance load like headphones because they're not designed to supply the amount of current required to drive that low impedance load. This can potentially result in damage to the output circuit.

[Greg C.]

Or an inline isolation transformer. I use these http://whirlwindusa.com/catalog/black-boxes-effects-and-dis/transformers-isolation-devices/isoxl and the only B********r product I endorse! http://www.behringer.com/EN/Products/HD400.aspx Stops the 48v and cancels all sorts of annoying hums into the bargain. Cheaper and smaller than a Di if you don't otherwise need it.

For iso transformers, I'll recommend the Whirlwind ISO1 or ISO2 instead of the XL. Smaller form factor iso transformers tend to saturate and distort causing low frequency roll-off if you hit them with a lot of low end. The physically larger transformer in the ISO1/2 boxes can take hot levels without saturation and they don't cost much more. They also have 1/4" in and out along with the XLRs. http://whirlwindusa.com/catalog/black-boxes-effects-and-dis/transformers-isolation-devices/iso-1

[sam.spoons]

If you're in Euroville buy these http://www.orchid-electronics.co.uk/dual_isolator.htm, cheaper than Whirlwind and at least as good quality.

[Greg C.]

If you're in Euroville buy these http://www.orchid-electronics.co.uk/dual_isolator.htm, cheaper than Whirlwind and at least as good quality.

If they don't publish the specs, how do you know it's as good as the WW? For that kind of money, it would be difficult to produce truly high quality transformers. So I'm skeptical. The Whirlwind ISO 1 and ISO 2 uses their TRSP600L transformer which has max input of +20dBu at 20Hz before saturation and +26dBu before saturation from 100Hz on up. Those are pretty good specs. The only better transformers on the market are made by Jensen and Lundahl.

[ILC Saratoga]

Configuration is Headphone jack (out) to XLR input channel 16.  Aux 2 to Mac Mini Input.

Very wrong, you should use the TRS "line input" jack on channel 16 that has no phantom on it - or an isolating DI - for any non-microphone input source. You could have just as easily fried a keyboard, acoustic guitar, submixer, or an amp DI output. Unfortunately this is a common problem amongst non-pro users . Expensive education for you but now you know .

And we have todays winner.  Yes, a possible expensive education  , aside from the amount of time spent.  Todays correct solution is a 1/8 stereo and either a split configuration to two of the TRS 1/4" plugs and link them for stereo or a single 1/8 stereo to 1/4" to the TRS 12-16 plug.  This avoids the circuit frying 48v phantom power.   This obviously falls under the WTH category and I'd love to accept total blame but I did have a professional help with the install of the mixer.  Thank you all very much for your assistance.  Now if I can just get the recording off the iPad without a lot of pain I would be good to go.

[WK154]

So  send the "professional" the bill and use something like VoiceRecord to deal with the pain of getting it off the iPad/Mac mini or if your really into PC's or Mac's iPad File Explorer.