ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2  All   Go Down

Author Topic: Dropping 100v speaker signal down to line input  (Read 605 times)

Gary Fitzpatrick

  • Full Member
  • ***
  • Offline Offline
  • Posts: 103
  • Fermanagh, Ireland
Dropping 100v speaker signal down to line input
« on: June 02, 2018, 12:02:53 pm »

Hi,

So I have a few projects coming up where I need to get an audio feed into a camera. The easiest and shortest cable run would have me connecting into the 100v speaker lines going to the speakers in the church. Is it okay to use a standard 100v 8/16 ohm transformer to drop the signal down?
 


Sent from my iPhone using Tapatalk
Logged
Allen Heath GL2000, EV sx300 over Community pro Subs, EV s-200 monitors, Zeck amplification

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 15971
  • Hickory, Mississippi, USA
    • Resotune
Re: Dropping 100v speaker signal down to line input
« Reply #1 on: June 02, 2018, 02:19:23 pm »

Hi,

So I have a few projects coming up where I need to get an audio feed into a camera. The easiest and shortest cable run would have me connecting into the 100v speaker lines going to the speakers in the church. Is it okay to use a standard 100v 8/16 ohm transformer to drop the signal down?
 



It might still be a little hot depending on how many watts it is tapped to deliver (less watts is better).
 
JR
Logged
On the internet people tell you everything "they" know, not the answer to "your" question.....  http://circularscience.com/

Gary Fitzpatrick

  • Full Member
  • ***
  • Offline Offline
  • Posts: 103
  • Fermanagh, Ireland
Re: Dropping 100v speaker signal down to line input
« Reply #2 on: June 02, 2018, 03:19:16 pm »



It might still be a little hot depending on how many watts it is tapped to deliver (less watts is better).
 
JR
Thanks For the reply JR. what would you recommend for dropping it down? I see quite a few of these systems coming on board (it is for streaming church services) so I wouldn’t mind doing it “right”

Gary


Sent from my iPhone using Tapatalk
Logged
Allen Heath GL2000, EV sx300 over Community pro Subs, EV s-200 monitors, Zeck amplification

Geoff Doane

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 789
  • Halifax, NS
Re: Dropping 100v speaker signal down to line input
« Reply #3 on: June 02, 2018, 04:02:37 pm »

1W into 8Ω is about 2.8 Vrms.  If you allow 6 or 7 dB for the crest factor of the signal, that takes you down to an average level of just about +4 dBu.  Chances are the crest factor is higher than that (average level is lower), but it looks like you'd be in the right ballpark, using the 1W tap on a transformer designed for an 8Ω speaker.

GTD
Logged

Gary Fitzpatrick

  • Full Member
  • ***
  • Offline Offline
  • Posts: 103
  • Fermanagh, Ireland
Re: Dropping 100v speaker signal down to line input
« Reply #4 on: June 02, 2018, 04:06:13 pm »

That’s great...thanks for the advice.

Gary


Sent from my iPhone using Tapatalk
Logged
Allen Heath GL2000, EV sx300 over Community pro Subs, EV s-200 monitors, Zeck amplification

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 15971
  • Hickory, Mississippi, USA
    • Resotune
Re: Dropping 100v speaker signal down to line input
« Reply #5 on: June 02, 2018, 05:36:36 pm »

Cheapest and easiest is a resistor pad, but a transformer will give you isolation which could be useful.

Try it and see... A wrong size (too hot) transformer can still be combined with a resistor pad to dial it in, while keeping the transformer isolation.

JR
Logged
On the internet people tell you everything "they" know, not the answer to "your" question.....  http://circularscience.com/

Gary Fitzpatrick

  • Full Member
  • ***
  • Offline Offline
  • Posts: 103
  • Fermanagh, Ireland
Re: Dropping 100v speaker signal down to line input
« Reply #6 on: June 02, 2018, 06:02:56 pm »

Cheapest and easiest is a resistor pad, but a transformer will give you isolation which could be useful.

Try it and see... A wrong size (too hot) transformer can still be combined with a resistor pad to dial it in, while keeping the transformer isolation.

JR
Do you mean like a 100v rotary attenuators? Like this one?

http://cpc.farnell.com/unbranded/p605d/line-attenuator-switch-12w/dp/AR71993

Gary


Sent from my iPhone using Tapatalk
Logged
Allen Heath GL2000, EV sx300 over Community pro Subs, EV s-200 monitors, Zeck amplification

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 15971
  • Hickory, Mississippi, USA
    • Resotune
Re: Dropping 100v speaker signal down to line input
« Reply #7 on: June 02, 2018, 07:04:58 pm »

Do you mean like a 100v rotary attenuators? Like this one?

http://cpc.farnell.com/unbranded/p605d/line-attenuator-switch-12w/dp/AR71993

Gary


Sent from my iPhone using Tapatalk
no.. don't know what that does.

JR
Logged
On the internet people tell you everything "they" know, not the answer to "your" question.....  http://circularscience.com/

TJ (Tom) Cornish

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 4088
  • St. Paul, MN
Re: Dropping 100v speaker signal down to line input
« Reply #8 on: June 02, 2018, 08:55:06 pm »

Hi,

So I have a few projects coming up where I need to get an audio feed into a camera. The easiest and shortest cable run would have me connecting into the 100v speaker lines going to the speakers in the church. Is it okay to use a standard 100v 8/16 ohm transformer to drop the signal down?
 


Sent from my iPhone using Tapatalk
100v systems are only 100v at full-tilt boogie; in practice you're probably a lot less than that.  Even if you are operating around 100v, that's still not a particularly big deal.  A isolation transformer box or DI box with a 20dB pad would get you from 100v at clipping down to around 6 volts at clipping, which should be well within the capabilities of a professional-level line-level input.  If you need to drop it for a consumer-level input, you might need more gain reduction, but there are DIs that have larger pads than that.  The Rolls Matchbox DB25 comes to mind, and has a selectable 20dB and 40dB pad.

Logged

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 15971
  • Hickory, Mississippi, USA
    • Resotune
Re: Dropping 100v speaker signal down to line input
« Reply #9 on: June 03, 2018, 10:42:54 am »

100v systems are only 100v at full-tilt boogie; in practice you're probably a lot less than that.  Even if you are operating around 100v, that's still not a particularly big deal.  A isolation transformer box or DI box with a 20dB pad would get you from 100v at clipping down to around 6 volts at clipping, which should be well within the capabilities of a professional-level line-level input.  If you need to drop it for a consumer-level input, you might need more gain reduction, but there are DIs that have larger pads than that.  The Rolls Matchbox DB25 comes to mind, and has a selectable 20dB and 40dB pad.
Check with the DI mfr before putting 100V into a DI.

I am not very confident about doing that.

JR
Logged
On the internet people tell you everything "they" know, not the answer to "your" question.....  http://circularscience.com/
Pages: [1] 2  All   Go Up
 


Page created in 0.038 seconds with 23 queries.