A question on Impedence

[Wadge]

Hi guys,

I am looking for some advice on an area I don't much understand.

With my band we are looking to use a distribution headphone amp to power individual mixes.

I was considering using a microphone splitter to split the microphone signals and send one split to FOH and the other split to the headphone amp.

I was considering using a Art S8 to split the signal and a Presonus HP60 as the distribution headphone amp.

My concern is the following: Out from the splitter, I will get a low impedence microphone signal. The manual says that the output impedence is 'Less than 255 Ohms at 1K Hz (Typical output load impedance is 1K Ohms)'

On the headphone amp side, the manual says that the input is as follows:
Type ................................................................................¼” TRS Stereo Unbalanced Input Impedance ............................................................................................... 10kΩ
Gain Range ........................................................................................... -96 to +10dB

My worry is that the output impedence from the splitter seems to be far lower that the input impedence on the headphone amp. In fact, the headphone distribution amp seems to be intended to fed from a DAW rather than from a microphone signal. Would I have such a weak imput signal as to have to drive the amp really high?

As you may tell, I don't know much about this stuff so any help would be greatly appreciated.

 

[s0c9]

I'm not sure it matters at the power levels (-4/+10dBu) you are working with..
You may have to turn up the gain on the HP60 and possibly won't need the pads on the S8

 

[Wadge]

I wasn't planning on padding the inputs. I am worried that I might have to turn up the gain on the HP60 pretty substantially to get any usable volume.

 

[s0c9]

I wasn't planning on padding the inputs. I am worried that I might have to turn up the gain on the HP60 pretty substantially to get any usable volume.

The only downside to that is that in doing so, you may increase the ambient noise floor.
Not really the kind of thing you can try until you get it "in hand" ...

 

[Wadge]

Just a quick update. I did some tests and tried to plug in a microphone into a line level input. It turns out that indeed a low impedance microphone signal is very weak and you'd need to crank the amp up to ridiculous levels to get any meaningful volume out of it.

The microphone level signal needs to be preamped to line level to be able to be used.

 

[stevenA800]

The HP60 wants to see a line level input. The S8 provides mic level so you will need preamps/mixer to feed the HP60. Have you looked at monitor mixers?

 

[Wadge]

You are indeed correct. I did a test and the mic level inputs are indeed to low - the headphone amp would need to be cranked up way too high.

I am pursuing a simpler albeit more expensive route - we shall be adding a Presonus RM32AI mixer to our current Presonus SL 32.4.2 to give us a further 16 aux outputs to play with. With both the SL32.4.2 and the RM32Ai, connected via AVB we'll have a total of 30 Auxes or 15 Stereo in ear monitor mixes available.

 

[EastCoastThump]

With my band we are looking to use a distribution headphone amp to power individual mixes...I was considering using a microphone splitter to split the microphone signals and send one split to FOH and the other split to the headphone amp.

The splitter suggests that you regularly need to have the band's monitor mixer play nicely with venue-provided FOH PA. But you have a SL 32.4 already...

Is your band's SL 32.4.2 for monitor mixing, or for band-provided FOH PA? Both? Seems like plenty of auxes there for most small bands, especially if you have an HP60 so you can build multiple IEM mixes on the shared A + B mixes.

 

[Wadge]

The splitter suggests that you regularly need to have the band's monitor mixer play nicely with venue-provided FOH PA. But you have a SL 32.4 already...

Is your band's SL 32.4.2 for monitor mixing, or for band-provided FOH PA? Both? Seems like plenty of auxes there for most small bands, especially if you have an HP60 so you can build multiple IEM mixes on the shared A + B mixes.

We're a pretty big band. At the very least 9 musicians, more typically 11 musicians and sometimes up to 17 people, so not a small band by any means - drums, bass, keys, guitar, 5 saxes, 4 trumpets, 4 trombones, singer.

check us out:

So far we've been using the SL 32.4.2 for both FOH and monitor mixing. The rhythm section and singer are on stereo mixes - that eats up 10 Auxes. We were using three of the remaining 4 Auxes on the 32.4.2 as sends to 3 floor wedges (1 for the saxes, 1 for the trumpets and 1 for the trombones).

We're looking to have the sax and brass sections on wired stereo in ear monitors so the more mix busses we have the better. So we'll continue to use the AUX outputs from the SL remote but we'll have 16 extra auxes to use from the Presonus RM mixer.

 

[s0c9]

So we'll continue to use the AUX outputs from the SL remote but we'll have 16 extra auxes to use from the Presonus RM mixer.

Sounds like this is going to be the best solution.. it gives you all those extra AUX busses for IEM mixes..