Input Sensitivity: 1V - What does that mean?

ATC & other manufacturers design parameters, technical queries etc
Posts: 15
Joined: Fri Nov 17, 2017 4:27 pm

Input Sensitivity: 1V - What does that mean?

Postby Allan » Thu Mar 08, 2018 9:57 am

I understand the sensitivity figure for passive speakers, it's usually expressed as a number of dB's for 1 Watt input measured 1 metre from the speaker.

On the ATC website, the sensitivity figure for the active speaker is expressed simply as a voltage, usually 1 volt. What does that mean though? Does it mean 1 volt at the input generates a particular number of dB's of sound pressure level at a particular distance? If so, what are these values.

The 1 volt figure looks to be consistent across the range, so does a 1 volt input generate the same dB output for all speaker models?

Posts: 235
Joined: Sat Nov 30, 2013 2:29 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby darrenyeats » Thu Mar 08, 2018 7:55 pm

It just refers to the voltage level input the electronics can handle. Some models can also be adjusted to 2V, which reduces the loudness by about 6dB.

The loudness out of the speaker varies by model. The bigger speakers are louder (more efficient bass drivers).

Posts: 15
Joined: Fri Nov 17, 2017 4:27 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Allan » Fri Mar 09, 2018 12:21 am

Ok, thanks Darren. So, sounds like a 1V input produces the maximum output level before onset of clipping or severe distortion from the drive units.

Not sure if that's typical of input sensitivity across the active speaker industry but it does seem quite sensitive and explains why I need to keep the volume of my pre-amp (feeding SCM19A's) at quite a low level. 0db on my pre-amp represents 2v max output on the phono outputs, 4v on the balanced outputs. So using the balanced outs, it seems the volume level needs to be taken down 12db just to get the pre-amp output down to the maximum safe input level for the speakers, if I've understood correctly. Obviously the volume needs taking down further from there to reach a comfortable listening level, and based on typical volume settings another 25db or so down from that -12dB point, based on -35 to -40db being a typical volume setting on the pre-amp.

Normally with an analogue pre that wouldn't be a problem but I'm using a Digital Volume Control, so that's quite a loss in bit depth for the DAC to deal with. It's a pity the domestic speakers don't have the switchable input sensitivity that the pro speakers have, that would help to an extent. However, sounds pretty good as-is, but thinking I possibly need to consider bypassing the DVC built into my streamer and using a separate analogue pre-amp instead, just out of curiosity if nothing else.

Posts: 142
Joined: Mon Mar 25, 2013 1:09 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Dogill » Fri Mar 09, 2018 3:59 pm

I agree the ATCs' sensitivity is not good for digital volume controls , I have a DAC with an adjustable output but even on its lowest settings some recordings need a low volume setting.
Weiss DAC 502, ATC100SE

Posts: 15
Joined: Fri Nov 17, 2017 4:27 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Allan » Fri Mar 09, 2018 8:50 pm

Thanks for the back up Dogill. After my last post I had a browse through the historical posts in this section of the forum and found quite a few posters with similar concerns.

So, I had a quick check to see what the outputs levels are for other typical devices with digital volume control and balanced outputs, this is what I found:

Benchmark DAC3: 18.3V
Mytek Brooklyn: 9.8V
Chord Hugo TT: 5.9V

My device, by the way, is a Linn Akurate DS/1

How about a friendly suggestion to ATC if they are reading this. How about considering revising the current amp pack for domestic speakers at some future point to have an input sensitivity of 2V, switchable to 4V? I can not imagine this would cause a problem for any relatively modern partnering electronics.

Alternatively, is there a single switch or pot inside the amp-pack that could be easily flipped or adjusted (by the retailer or factory if necessary) to reduce the sensitivity?

User avatar
Posts: 680
Joined: Tue Jun 15, 2010 12:59 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby AlmaataKZ » Sun Mar 11, 2018 12:37 am

Attenuators are available from pro gear shops for little money. This is what I use.
iMac/Bluray/PVR - Marantz SR7008 - 7.1 ATC SCM50SLAT fronts, C1C centre, SCM7 rears, MonitoAudio M3 rear surr, C4 sub
Airplay multiroom (aex to genelec 6010, b&w mm1, avi dm10)
System here: http://atcforums.co.uk/viewtopic.php?f=16&t=667

Posts: 15
Joined: Fri Nov 17, 2017 4:27 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Allan » Sun Mar 11, 2018 4:18 pm

Thanks for the suggestion. How much attenuation are using in your setup?

User avatar
Posts: 10
Joined: Thu Sep 15, 2011 8:47 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby a.diabelli » Tue Mar 13, 2018 12:46 pm

Allan wrote:Thanks for the suggestion. How much attenuation are using in your setup?


Hi,
you can buy a model with adjustable attenuation like this one:

https://www.jts-europe.com/products/microphones-and-wireless-systems/accessories/ma-123/

BTW, I have a setup similar to you (ATC SCM40A and Naim NAC-N 272) same problem also with the Naim, so I've ordered the MA-123, I'm waiting for deliver..

Another more drastical solution is to move to a DAC/Pre with output level switchable like these:

https://www.rme-audio.de/en/products/adi_2-dac.php
http://www.violectric.de/index.php/produktdetails/product/DAC_V800.html

Marco

Posts: 24
Joined: Wed Mar 13, 2013 10:48 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Alastair » Tue Mar 13, 2018 8:56 pm

+1 for the attenuator option.

This makes quite a difference in my view with regard to volume control options and also the reduction in noise.

With a baby I do a fair bit of listening at low volumes, so I find the attenuators very useful.

I've just switched pre amps, as I wanted to run my dac balanced out into my pre (along with several other balanced sources) and immediately I can hear a dramatic drop in noise, compared to no attenuators in the system. I am using Rothwell XLR ones.

Not sure how attenuators are received, die hard purists might have an issue with them but I think they are well worth a punt. About the cost of 1 tank of fuel. So not the end of the world if they don't work for you, in my humble view.
Sys 1: ATC SCM100A / dCS Network Bridge, Purcell, Elgar Plus / Oppo 203 / Meridian G02, MC200, MS200
Sys 2: Meridian DSP5000 96/24 with AC200
Roon & Tidal

Posts: 235
Joined: Sat Nov 30, 2013 2:29 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby darrenyeats » Thu Mar 15, 2018 9:38 am

Since you poked the bear with the die-hard comment, I'm one of them! Attenuators affect impedance relationships, whether this matters though depends on the situation. If you use them I read somewhere they should be located at the load end (not source)?

I've decided my DAC works better about -25dB digital volume than higher. Not sure why but it's more relaxed. Day to day I end up about -30dB to -20dB and occasionally a little outside. It's fine within that zone at least but then the digital volume is done right (same bit depth as the converter and dithered). It's not to do with line input overload or even speaker distortion - this applies just the same via 50s and my Stax energiser/Muamp 'stat headphones, even though I use the volume pot on the Stax.
Last edited by darrenyeats on Sat Mar 24, 2018 12:27 pm, edited 2 times in total.

Posts: 24
Joined: Wed Mar 13, 2013 10:48 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Alastair » Thu Mar 15, 2018 7:34 pm

darrenyeats wrote:Since you poked the bear with the die-hard comment, I'm one of them! Attenuators affect impedance relationships, whether this matters though depends on the situation. If you use them I read somewhere they should be located at the load end (not source)?

I've decided my DAC works better about -25dB digital volume than higher. Not sure why but it's more relaxed. Day to day I end up about -30dB to -20dB and occasionally a little outside. It's fine within that zone at least but then the digital volume is done right (same bit depth as the converter and dithered).

It's not to do with line input overload or even speaker distortion since my above comments apply just the same via 50s and my Stax energiser/'stat headphones, even though I use the volume pot on the Stax.


Hi Darren,

What does the impedance relationship mean, in practice?

Rothwell do both options i.e. Those for CD player outputs and those that sit on the power amp inputs. I've used both options with success.

Thanks
Alastair
Sys 1: ATC SCM100A / dCS Network Bridge, Purcell, Elgar Plus / Oppo 203 / Meridian G02, MC200, MS200
Sys 2: Meridian DSP5000 96/24 with AC200
Roon & Tidal

Posts: 441
Joined: Wed Dec 21, 2011 7:01 pm
Location: Las Vegas, Nevada, USA

Re: Input Sensitivity: 1V - What does that mean?

Postby Brad Lunde » Mon Mar 19, 2018 3:41 pm

Let me re write this, I poorly explained it.

Brad
Brad Lunde
Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

User avatar
Posts: 680
Joined: Tue Jun 15, 2010 12:59 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby AlmaataKZ » Mon Mar 19, 2018 9:18 pm

Allan wrote:Thanks for the suggestion. How much attenuation are using in your setup?



I used 20dB but depends on the needs i.e. Your gan structure. Various levels of attenuation can be bought.
iMac/Bluray/PVR - Marantz SR7008 - 7.1 ATC SCM50SLAT fronts, C1C centre, SCM7 rears, MonitoAudio M3 rear surr, C4 sub
Airplay multiroom (aex to genelec 6010, b&w mm1, avi dm10)
System here: http://atcforums.co.uk/viewtopic.php?f=16&t=667

Posts: 15
Joined: Fri Nov 17, 2017 4:27 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby Allan » Mon Mar 19, 2018 9:41 pm

Thanks AlmaataKZ. 20db, that's quite a *lot*. If my calculations are correct, that's reducing the voltage output from your source to about one seventieth, or less. Further evidence, I think, that the domestic speaker sensitivity is higher than necessary.

Posts: 235
Joined: Sat Nov 30, 2013 2:29 pm

Re: Input Sensitivity: 1V - What does that mean?

Postby darrenyeats » Sat Mar 24, 2018 12:02 pm

Alastair wrote:
darrenyeats wrote:Hi Darren,

What does the impedance relationship mean, in practice?

Rothwell do both options i.e. Those for CD player outputs and those that sit on the power amp inputs. I've used both options with success.

Thanks
Alastair

My grasp of the technicalities is basic. Also I am not that sure how those technicalities map to audible sound in different situations.

When I listen I perceive the XLR attenuators built into my DAC disturb the sound. I have attributed this to the impedance change, since this is what I know about, but something else might be in action. I've also been told that attenuators at the DAC end may indeed be a problem where attenuators at the load end might not, but that part is now beyond my basic knowledge so coming from me is hearsay.

There are other schemes available, for example Weiss attenuate by changing reference voltage into the DAC chip, this avoids adding resistor networks in the signal path. I guess this isn't more common because it's expensive. In the absence of something like this, IME digital volume control dithered at the same bit depth as the D/A converter, within a reasonable range (down to say -30dB), isn't disturbing where my DAC attenuators are.

Sorry I can't be more of help.

Next

Return to Technical area

Who is online

Users browsing this forum: No registered users and 2 guests