KEMPER STAGE - LIVE - ACTIVE OR PASSIVE DI

hey,

i want to protect my kemper from phantom power(our mixer is on the phantom in all inputs)

i know that the XLR outputs of the kemper are protected but I want to be sure.

do i need active or passive DI?

On the one hand I play electric guitar with passive pickups (so I would think about active DI) , On the other hand the signal

of the electric guitar goes through the kemper, and the signal going from the kemper to the mixer pretty loud (so I would think about passive DI)

so what DI do i need?

thank you

Quote from drog

The rule of thumb is how are you connecting to the board. With an active source or passive.The Kemper is active (powered) you would want to use a passive D.I. If you were plug a guitar directly into the board without the Kemper, you would then want an active D.I. as your source is passive.

So the answer to your question is passive D.I.

thank you very much.

Just for understanding, If I connect active DI after the kemper anyway, That would be a problem?

thanks again

Quote from drog

If you choose a high quality active D.I. you should be ok. You could however overload it and create unwanted distortion/noise. That is why for an active source you typically choose a passive D.I.

The other part is how much you want to colour your sound, active will add more of its sound than a good passive unit.

A simple passive D.I. is just a transformer. Active D.I adds a preamp along with it.

Active D.I. sometimes add other features that you might want as well and could also be used as backup if you needed to plug guitar in direct or want to use it on other instruments.

I would spend a bit more and get a good one at that point.

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And if I connect bass with passive pickups to the kemper, the answer is the same?

The better option is a passive DI ?

Quote from drog

Yes, passive would be the way to go, as the Kemper is the source and not the instrument. I would however advise you to buy a good quality D.I. as there is a difference in the quality of transformers that are used.

ok, thank you very much for your help!

Quote from slateboy

Likewise, I understand the kemper needs no such device as it delivers a balanced output with protection from phantom power.

Would a guarantee from the manufacturer give you the reassurance you seek?

There is always a minor risk connecting your gear to other equipment as you can never be 100% certain the external gear is without having fault. Maybe the di box will eliminate this risk or at the very least give you peace of mind.

there is a guarantee from the manufacturer , but they recommend avoiding it

this is from the user manual of the kemper :

"The XLR outputs are protected against 48V
phantom power fed by a mixing desk. However, you should avoid feeding phantom power into the PROFILER if you
want the best audio quality"

Quote from slateboy

bit of a catch 22, i guess, as a DI box may compromise the sound albeit hardly noticeable.

I do always ask the sound-crew to ensure phantom is off but i'm never 100% confident my request will be maintained.

How about a phantom power blocker?

https://www.thomann.de/gb/tritonaudio_phantom_blocker.htm

(i'm sure other makes and retailers are available)

You could probably even make one if you're handy with a bit of soldering?

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I will find out about phantom power blocker.

thank you

Quote from EdwardArnold

Happened to be reading back through this thread, and while the OP has found a suitable solution (a phantom power blocker) I though it might be useful for others reading to clear up some information on different devices:

1. Phantom power blocker - contains DC blocking caps that prevent damage to sensitive mics and equipment such as ribbon mics.
2. Passive DI box - contains a transformer, which can usually be tapped at various points so that it can be 1:1, or step down with attenuation switches marked e.g. 0dB (unity) -20dB and -40dB although this is impacting upon impedance and may be sub-optimal; input and output impedances are also dependent on what is connected to the DI box, so you're not going to find a perfect 'one-box-solution' for mic, instrument, line and speaker level sources. Unless a high quality (=expensive) transformer is used, it is likely to add harmonic distortion particularly at low frequencies, especially when driven beyond the parameters it was optimised for. A linear frequency response is also unlikely on more affordable units, but this isn't always an issue for guitar as it is most likely to be a drop-off at either end of the frequency spectrum.
   Passive DIs have the advantage that there is physical isolation of lines, adding more protection against wayward voltage under certain failure conditions. You have to be careful where you place a passive DI though; if it is near a mains transformer it will induce hum.
3. Active DI box - no transformer - uses active electronic circuitry to present a constant input impedance to the source (Kemper in this case) and a constant output impedance to the destination (mixer). Given that it is already an active unit, you can often find models that also incorporate further active processing such as EQ or pre-amplification. This is where 'active' gets confused with meaning 'preamp'. An active preamp doesn't mean that it will amplify the signal; a 'basic' active DI has all the same applications source-wise as a passive, except that it may well have a more linear frequency response and be less prone to harmonic distortion due to the design of the circuit, and the cost is likely to reflect this. The active circuit can also provide the -20dB, -40dB etc. to attenuate input levels without it also affecting the impedance, so the efficient voltage transfer that you require for your signal to pass unencumbered can happen. No physical isolation, requires either battery or phantom power to operate. I think the 'active = larger signal' association comes from active guitar pickup systems, where the pickup system contains a preamp as part of its active electronics. It wouldn't be the first time the guitar world has blurred our definitions a little (I'm looking at you, tremolo arm!).
4. Line Isolating Transformer - contains a 1:1 transformer, and is very much the same as a passive D.I. in concept but the impedance values based on transformer windings are suitable or line level sources and destinations. While mic level signals are typically less than 1V, line level can be up to around 8V, driven by a source impedance of less than 100 ohms, with the output connected to a mixer or active speaker input (for example) that will typically be 10k ohms. The impedance of a 'mic level DI' with a step-down ration will be wildly inappropriate for line level sources, hence, these are different devices.
   Also provides isolation from voltage shorts through connected equipment. Usually features ground lift in addition to isolation through transformer to help solve a number of issues with humming monitors, speakers etc.

Happy to discuss any of the above if I've missed something.
All the best

wow.

thanks!!!

so the kemper is actually a active DI ?

Quote from EdwardArnold

No, the Kemper does not provide the functions of a DI box as it outputs line level signal rather than low impedance mic-level signal. The latter would be required to a) feed a mic input on a mixer and b) drive long mic cable distances without degradation. So, you often still need a DI box unless you have a mixer input with built-in mic/line switching or pad functions (these are actually quite common on stageboxes that accompany digital desks, and highly useful).
You can use either active or passive DIs with the Kemper, just be aware of the pros and cons as outlined above. Radial make great examples of both. If I could carry only one it would be passive.

If it’s a mixer with a separate TRS Line input (common) you can connect straight to that from the Kemper’s output, with an XLR>TRS cable for example. This is great until you need to drive long cable runs through a multicore back to the desk. That said, the Kemper line output drivers are good. Chances are onstage though that you’ll only be given a wall box that feeds mic inputs on an in-house mixer. I’ve found that asking a hired-in engineer to start re-patching to line ins is asking for trouble, so I much prefer the idea of presenting a pair of D.I. outputs they can pick up.

What can catch people out is on the back of the Rack and Toaster, you have a ‘Direct Output’ but this is an unbalanced 1/4” TS jack, and its level varies depending on where you choose to feed it from in the signal path, but it will never be low impedance mic level or balanced as that is not its purpose.

I’m wondering if I confused things by putting “..(the Kemper in this case)...” ? I was referring to the Kemper being the source connected to the input of the active DI, not it being the active DI itself.

If this doesn’t clear things up still let me know and I’ll give it another crack.

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it's all clear.

but in the first massage you said : "(Kemper in this case)" when you talked about active DI,

and in second massage you said : "If I could carry only one it would be passive"

Quote from EdwardArnold

I see it:

“..uses active electronic circuitry to present a constant input impedance to the source (Kemper in this case)..”

By this I meant, “The active DI presents a constant impedance to the source device feeding it, which in this example would be your Kemper.”

Apologies for the confusion.

If I only had the option of picking one DI to take to gigs, I would take my passive one, not an active one, despite some of its drawbacks. My reasons are based on my own experience of the advantages and disadvantages of active and passive. For example, a passive DI has helped save some of my gear from damage due to the transformer isolation and it’s also simpler as it doesn’t require phantom power. I’ve had a few gigs where the supplied XLR cables have dropped a pin 2 or 3 connection. With a passive DI audio will still pass, albeit unbalanced and 6dB down, but an active DI will no longer receive phantom power and you’ll have no signal (mine isn’t battery powered).
If I’m recording somewhere though I’ll use the active Radial DI as the particular mode I own sounds better to me than my passive one.

Lots to consider, hence I’m trying to shine a little light in the subject; there’s more to it than first meets the eye

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And if I connect the kemper to passive DI (a good one, like JDI radial), the input level of the DI and the output level of the DI is the same?

That is, does the passive DI lower me the level of the signal?

Quote from EdwardArnold

Yes, the passive Radial JDI will lower your signal level. It takes your high level, high impedance signal down to a low level, low impedance mic signal.

Kemper (line level) --> JDI = use the -15dB pad switch

Passive electric guitar --> JDI = no input pad needed

There are both mono and stereo versions of the JDI, if you need. The stereo version is also perfectly happy being used for two separate mono signals/instruments, not just stereo from a single source.

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and what if i connect the kemper to JDI, like you said "Kemper (line level) --> JDI " , but i don't turn on the -15dB pad switch?