DI box(es) on a patchbay?!

[bradshc]

Hi all,

I have a small home studio with several hardware synths, effects boxes/pedals and an Apogee Element 88 audio interface “connected” via a couple of Samson S-Patch Plus patchbays.
I don’t use a mixer.

I recently took delivery of a lovely new Sequential Prophet 10 and promptly fried the main output by clumsily sending phantom power to it from my Element 88 (at least I think that’s what happened)
The synth still works perfectly (evidenced through the headphone output) but the main output is dead.
As soon as lockdown is lifted and non-essential services are open again I will get it to a tech to be fixed.

In the interim I’m planning to get a couple of Radial Technologies Pro-D2s to patch into inputs 1-4 of the Element 88, to prevent anything similar happening in future.
My question is, is it okay to do this through the patchbay?
ie. To have my 4 most-used synth outputs normalled to the 4 Pro-D2 inputs, but available to be overridden (by patching on the front panel) by other synth outputs, and the 4 Pro-D2 outputs normalled to inputs 1-4 of the Element 88, but available to be similarly overridden to the effects inputs on the patchbay, for example.

The objective being to avoid patching between equipment other than through the patchbay, if possible.

I Would very much appreciate your advice.

Thanks,
Conor

[Hugh Robjohns]

In the interim I’m planning to get a couple of Radial Technologies Pro-D2s to patch into inputs 1-4 of the Element 88, to prevent anything similar happening in future. My question is, is it okay to do this through the patchbay?

Not really....

DI boxes are designed to reduce line and instrument level signals to mic-level... but you really shouldn't connect microphone circuits through a conventional patch-bay. This is primarily because phantom power and A-type patch-bays don't play nicely together, and there is a real risk of the inherent shorts caused when plugging and unplugging can generate big voltage spikes that can damage or destroy both preamps and mic (and other gear).The other reason is because it's way too easy to screw up as you did and patch a line source accidentally into a mic preamp and fry something!

If you really want to use DI boxes and route balanced mic-level signals around, then that's fine, but mic level signals and preamp mic inputs should really be patched on XLR panels.

In your case, though, all your sources seem to be instrument level, so a much better idea would be to connect the TRS instrument inputs of channels 1-4 of the interface (which can never have phantom on them) to the bottom row of the patch-bay, and all your instruments to the top row, with the FX on the adjacent sockets as necessary... And that way you can easily plug instruments to FX pedals and inputs in whatever fashion you desire without risk!

[uselessoldman]

Is your techie not working? I got one of my amps serviced a couple of weeks ago, took advantage of them being a little more quiet than normal and parts suppliers are all open for business.

I have the S-Patch, awesome patch bay it can do anything you ask of it and it never complains.

So standard config is instrument signal comes in top rear and out the bottom rear. Using the switch at the front you can then break that signal chain and plug in the front bottom so the signal goes through and out the rear bottom or out the top front from the patch bay somewhere else like an effect loop and back in the bottom front.

Is that what you were asking? So in your case you would plug in the front bottom that would go through the rear bottom to your interface inputs.

[The Elf]

Wot Hugh said. Not sure why you feel the need for DIs? Are you using them to fix a problem?

[Hugh Robjohns]

Yes.

His interface appears to use XLRs for all the inputs which are all switchable mic/line, and it seems he has connected those to the patch-bay.

Consequently, he accidentally plugged an instrument into an input that was set to mic with phantom... and (rather disappointingly) his Prophet 10's line outputs appear to have gone phut!

Having shared mic/line inputs on XLRs is a really stoopid idea IMHO, but it's not uncommon, sadly.

Fortunately the first four input channels of the interface use combi-XLRs with instrument inputs on the TRS connection... Hence my configuration advice above.

[uselessoldman]

the purpose of DI box is to convert an unbalanced instrument signal (jacks) to a balanced line signal (XLR), guitars being the usual although yea it can also be used for some keyboards. Then you can run longer cables over XLR and without any signal interference.

Also cos now its a line output signal all interface inputs should accept it, not just a dedicated instrument input when you assign line input over mic for example.

Your synths should ALREADY be balanced line output??? if not then if the signal is unbalanced using a DI box would convert it to balanced. that is from a instrument output to a line output.

I agree with you Hugh, shared XLR/Jack balanced/unbalanced mic/line/instrument sockets on a audio interface with Phantom power is CRAZY silly. Especially considering this is not a cheap interface NOR are his instruments.

[Hugh Robjohns]

the purpose of DI box is to convert an unbalanced instrument signal (jacks) to a balanced line signal (XLR)

Not quite... the unbalanced instrument / line / speaker level (depending on the box and its settings) input signal is brought down to a nominal mic level signal. The idea is to feed the signal into a mic preamp. Some DI boxes provide hotter signals than others, but I know of none that manage genuine line level.

Your synths should ALREADY be balanced line output???

Some synths are equipped with balanced line-level outputs, but most — including the Prophet 10 — have unbalanced outputs at a nominal instrument-level (although many can drive line inputs quite happily with the volume control turned up).

using a DI box would convert it to balanced. that is from a instrument output to a line output.

For that particular role, you'd actually be better off using a line isolator box like the ART CleanboxII or the ART DTI. These boxes use transformers to balance the outputs, but the transformers are 1:1 so maintain the source signal level, instead of stepping the signal level down to mic level in the way a conventional (active or passive) DI box does.

[The Elf]

Having shared mic/line inputs on XLRs is a really stoopid idea IMHO, but it's not uncommon, sadly.

I like combi sockets, and line/mic switchable is fine too - as long as phantom never makes it to the jack connection. IME that's usually the case.

So, yep all this needs is a jack connection - no need for DIs.

[bradshc]

Yes.

His interface appears to use XLRs for all the inputs which are all switchable mic/line, and it seems he has connected those to the patch-bay.

Consequently, he accidentally plugged an instrument into an input that was set to mic with phantom... and (rather disappointingly) his Prophet 10's line outputs appear to have gone phut!

Having shared mic/line inputs on XLRs is a really stoopid idea IMHO, but it's not uncommon, sadly.

Fortunately the first four input channels of the interface use combi-XLRs with instrument inputs on the TRS connection... Hence my configuration advice above.

Exactly right, Hugh... I have all 8 inputs on the Element 88 connected to the patchbay via XLR to TRS cables.
It didn't occur to me that the TRS connection of the combi-XLRs connector would not receive phantom power, which of course makes perfect sense.

Thanks to everyone for the advice (and for saving me the cash I would have spent on the DIs that can now go towards getting the Prophet fixed up!)

[bradshc]

Is your techie not working? I got one of my amps serviced a couple of weeks ago, took advantage of them being a little more quiet than normal and parts suppliers are all open for business.

He works from a retail music shop (I don't have his mobile number, but I'll get it next time I get the chance!) and those are classed as non-essential and currently closed here in Ireland... until at least the first week in April.

[bradshc]

Wot Hugh said. Not sure why you feel the need for DIs? Are you using them to fix a problem?

I thought I was, but Hugh has set me straight

[uselessoldman]

SO you North or South not that it now makes any difference since you are both still in the EU that is a sore subject with my family right now.

Yeah I know a lot of none essential Businesses are currently closed, BUT ONLY TO THE PUBLIC, many are still at work cos they still get orders to complete for ESSENTIAL BUSINESSES who are still open or completing orders made on line.

whilst the rest of us have time on our hands to play with all our toys

[Mike Stranks]

So you North or South not that it now makes any difference since you are both still in the EU that is a sore subject with my family right now.

Yeah I know a lot of none essential Businesses are currently closed, but only to the public, many are still at work cos they still get orders to complete for essential businesses who are still open or completing orders made on line.

whilst the rest of us have time on our hands to play with all our toys

Fixed that for you...

I say again: CAPITALS IS SHOUTING in a forum post

[bradshc]

SO you North or South not that it now makes any difference since you are both still in the EU that is a sore subject with my family right now.

I’m in the South. No interest in the politics of it all, but economically the North really do seem to be caught in the middle. Can’t be easy.

whilst the rest of us have time on our hands to play with all our toys

Well, it’d be rude not to

[uselessoldman]

kudos to you bradshc, I look on with envy at your hardware, but my lass who is a Southerner would never tolerate such gross extravagance. She is always full of ideas on how I should spend my own money. Although it has taken her 6 years to get me to finally decorate my own place, I did hers the minute she moved in. I have this problem see, I cannot see my walls there covered with speaker cabinets !

[bradshc]

Quick update, for no other reason than to highlight Sequential's great customer service (in my opinion).

I checked with Sequential and getting the synth fixed by a local tech would have invalidated the warranty (there are no authorised repair centres in Ireland, unfortunately).
Fair enough.

However, for the paltry sum of $25, plus the the cost of sending the voice boards to Sequential in San Francisco (€27), they repaired the problem for me and paid for return postage, all within 3 weeks (most of which was transport time).

Result!

[Drew Stephenson]

Sounds pretty good to me!

[Martin Walker]

Wow, that IS impressive service!

No wonder they have such a good reputation among their customers.

Martin

[Arpangel]

I see no reason to worry about balanced outputs on keyboards and DI boxes in a home studio, it’s a waste of time, and just adds more things to go wrong.
Unless you’re running cables over many metres, in an RF hostile environment, it makes no sense.

[The Elf]

I disagree. The more balanced connections you can make the cleaner system as a whole you will have. It is neither complicated, nor inherently prone to problems. It's not a waste of time at all.

I can cite several studio owners that have been smacked of the gob when I've re-wired them with balanced cable and the veil has been lifted from their eyes and ears. Typically the response is 'why didn't I do this years ago?'.

(DI boxes would be my third choice.)

Use balanced cables every time you can. Your audio will thank you for it.

[Hugh Robjohns]

I see no reason...

I suspect that's because you don't understand the issues involved!

...just adds more things to go wrong.

There is nothing more to go wrong in a balanced interface.

Unless you’re running cables over many metres, in an RF hostile environment, it makes no sense.

You're right in that interference isn't the problem, but the balanced interface is about much more than just reducing interference.

In a complex studio with myriad connections between lots of different bits of equipment, ground loops are frequently a major problem and notoriously difficult to resolve.

The balanced interface, being fundamentally ground-free, eliminates that problem at a stroke (when implemented correctly).