Can you guys confirm that 1/4" TRS > XLR Male cables perfectly fine for Audio Interfaces with Balanced TRS outputs? Or would you use a DI anyway?
If your interface has balanced connections then you don’t need a DI box.
You should always use a di it adds a layer of protection between u and sound guy. For eg phantom power etc. Even guys at rme said to use
Also ground lift is sometimes needed
Hmm, I am a little confused. First of all, I was under the impression that RME interfaces had transformer outputs in which case a phantom return (which is DC) wouldn’t get through.
Also, DI boxes are intended to convert unbalanced signals (so just tip/sleeve) to balanced signals. So how do you feed in a signal that is already balanced?
Also ground loops are generally a problem with unbalanced inputs.
There are three things here to think about; connection, balancing, and level
Connection - going from TRS to XLR is absolutely fine. Both connectors can transmit fully balanced signals so if one end has TRS and the other XLR then no probs at all!
Balancing - as DHJ states, an unbalanced signal on TS puts signal on tip and ground on sleeve. Balances on TRS is signal + on tip, signal - on ring, and ground on sleeve. An unbalanced input will only have TS contacts - plugging a balanced TRS in to an unbalanced TS input wil simply ground the Ring (Signal -) and so the input ‘sees’ an unbalanced signal. So no issue with plugging balanced in to unbalanced input
Signal - here is the big one in terms of your question (I believe). 9/10 an interface will output signals at line level. However 9/10 a mixing desk will be expecting microphone level. As well as balancing a signal, a DI also drops the signal from line to microphone and ensures the output is at the correct impedance for what a mixer is expecting. This is really the main function of a DI, even though balancing is also a key part of it.
So, if your interface sends out line level and the equipment you are plugging in to can accept line level - whether the connector is TRS or XLR; it’s not important - then yes you can absolutely not use a DI and happy days.
If your interface sends out line level and the equipment you are plugging in to expects mic level/impedance then that’s when a DI is required, even if the output of the interface is balanced.
Generally speaking (as a musician and soundman) I would always put a DI on the output of an interface as will take the assumption that the output is line level and the mixer needs mic level/impedance. I’ve never had issues with this and as long as a decent DI is used then there will be zero signal degradation. If I’m 100% certain the interface is sending out mic level or the mixer can accept line then sometimes will not use a DI, but that is very rare.
Hope that helps
Be slightly careful with this - this is generally only true for DI’s with a transformer in the circuit; this will be all passive DI’s and some (generally higher end) active DI’s. As DHJ also mentioned above, the interface outputs may be transformer balanced in which case that offers the same ‘protection’ as a transformer balanced DI would.
As the question may well be asked…
Active Vs Passive DIs:
Passive DIs use a transformer to both balance the input signal and also drop it’s level and change its impedance. They are very simple and require no power. However, because they are so simple, the quality of the transformer makes a big difference - passive DIs are generally where it pays to spend a bit more (in my opinion).
Active DIs use a preamp and other electronics to do the balancing and signal conversion. Some higher end models may include a transformer as part of this. They are more complex and require power (battery or phantom) but it’s easier to make a good design more cheaply than it is to make a good, cheap transformer (although still worth not skimping on buying DIs I would say).
When to use passive - passive DIs work great when you have a strong input signal. So connected to a keyboard, or interface, or on the output of a preamp, or anything with a line level output, then passive is a good way to go.
When to use active - the bonus of an active pickup is the input electronics can handle low levels and high impedance better than a passive DI. Active boxes are perfect for instrument level signals - so acoustic guitars with no preamp, electric guitars to input in to an interface, bass guitars, any other instruments with a pickup but no electronics. However an active box will be equally as happy with a line level signal and can be used with those - but the output might be quite hot! There will generally be a 10-20dB pad on active DI boxes so you can lower the input signal.
Thanks guys im no sound guy but i do alot of gigs with alot of different sound companies and the general consensus is to use a di to be safe. I emailed rme and they said you dont have to but better to. Also dropping to mic level is the preferred method i think. Correct me if im wrong.
I only use passive di (radial d2)
Yeah, so a passive DI - like your DI2, which is great, use them myself - is a good ‘swiss army knife’ for your interface as you know:
a) the signal is definitely balanced
b) the signal is at the right level/impedance for a mixing desk
c) your interface is protected against phantom
That’s what I would do and it’s generally a good plan, however as explained above, if you are confident in the input/output equipment then it’s not always necessary.
Thank you so much for all this VALUABLE information. I asked this question because I’m assembling a smaller portable rig setup. In my primary setup, I utilize a Beheringer XR18 as a USB audio interface and analog mixer for my keys. Has great Mic level outputs built in.
Most interfaces, including the XR18 will actually output Pro Line level on their main outputs, not mic level. Pro Line level is different from the consumer line level.
Most mixing consoles will have a proper line level stereo pair inputs which expect this exact signal.
If you are plugging the output into a normal mic input on the front desk console then you should use a DI box - @speed12 gives excellent advice on this.
If you know that you are plugging into a “line in” stereo input - then you do not need it.
Verified. Absolutely correct. Thanx for the clarification.
That’s another good point - XLR != mic level ; it may very well be line level as EnjoyRC has found that his mixer outs are.
A way to think about it is: Is there a preamp in the equipment that is outputting the signal?
If so then 9/10 it will be a line level output. The other 1/10 is where there is some sort of internal DI like functionality where it outputs mic level.
(And that’s without getting in to consumer/Pro line level differences…)