• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Active Subwoofer input sensitivity

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
I have a presonus temblor T8 sub and edifier Mr4 speakers. I use topping d30 dac line out to sub line in and connect mr4s with balanced cables to sub out. Question is quarter gain on sub is too loud and rattling starts. When i dial down more there is no sound. Can it be the dac line out is excessive ? Another question is a cheap splmeter suitable for roughly acoustics measurement. I would be happy to buy an umik1 but i cannot.
 

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,891
Likes
35,912
Location
The Neitherlands
MR4 = -10dBV input = 0.3V the DAC is 2V out.
I suggest to use the D30 DAC in re-amp mode and set the output to -16dB
Set the sub level to match the speakers.

For a rough SPL estimate use a smart phone. The Apple ones seem to be fairly accurate.
 

staticV3

Master Contributor
Joined
Aug 29, 2019
Messages
7,540
Likes
12,014
There's no useful specs for the presonus sub so I don't know what its input sensitivity is like.
What you're describing certainly sounds like it wasn't designed for nominal 2.0/4.0Vrms.

If you've used the DACs XLR out so far, then you could try the RCA out instead.
Should the sub's gain be the same between inputs, then that would net you some more headroom.
If instead the sub compensates for the difference in amplitude between SE and Bal, then you'll be right back where you started.

Of course, you can always attenuate the signal digitally via either the DACs own volume control or a preamp in equalizer apo or similar.
The D30Pro is extremely low noise. It can take it.
 
Last edited:
OP
Y

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
MR4 = -10dBV input = 0.3V the DAC is 2V out.
I suggest to use the D30 DAC in re-amp mode and set the output to -16dB
Set the sub level to match the speakers.

For a rough SPL estimate use a smart phone. The Apple ones seem to be fairly accurate.
How can i ise d30 in preamp mode? It does not have volume knob?
Can a smartphone measure low frequencies?
 
OP
Y

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
There's no useful specs for the presonus sub so I don't know what its input sensitivity is like.
What you're describing certainly sounds like it wasn't designed for nominal 2.0/4.0Vrms.

If you've used the DACs XLR out so far, then you could try the RCA out instead.
Should the sub's gain be the same between inputs, then that would net you some more headroom.
If instead the sub compensates for the difference in amplitude between SE and Bal, then you'll be right back where you started.

Of course, you can always attenuate the signal digitally via either the DACs open volume control or a preamp in equalizer apo or similar.
The D30Pro is extremely low noise. It can take it.
Already d30 have only rca out. What is open volume control?
 

Eetu

Addicted to Fun and Learning
Forum Donor
Joined
Mar 11, 2020
Messages
763
Likes
1,180
Location
Helsinki
Previous comments seem to assume you have the D30 Pro which has volume control but seems you have the old D30?

Do you use a PC as your source? Could you tell us at what volume you have the Windows(?) system volume and the volume on whatever music player you use? Have you tried keeping the digital/source volume at a very low setting, you should get a more usable gain/volume range on the sub and speakers.
 
OP
Y

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
Previous comments seem to assume you have the D30 Pro which has volume control but seems you have the old D30?

Do you use a PC as your source? Could you tell us at what volume you have the Windows(?) system volume and the volume on whatever music player you use? Have you tried keeping the digital/source volume at a very low setting, you should get a more usable gain/volume range on the sub and speakers.
Yes it is the old version. Windows PC volume %50, deezer volume maxed. I am suspicious to lessen Windows volume more. Would not i loose resolution? Is it the best way?
 

DVDdoug

Major Contributor
Joined
May 27, 2021
Messages
2,921
Likes
3,836
Line level isn't well controlled/calibrated in home equipment... Usually the output has plenty of signal, and the amplifier has plenty of gain, so you can get full-power from the amp when you turn it up and "everything works OK".

Another question is a cheap splmeter suitable for roughly acoustics measurement.
Most SPL meters are A-weighted which is NOT what you want.

Would not i loose resolution?
Yes, but it may not be that bad... When you reduce the volume digitally you aren't using all of the bits. With "normal" digital attenuation it's not a problem because you can get-down to where you are only using a few bits and at that point you can't hear much of anything so you can't hear the loss of resolution.* Quiet parts on a CD, or the fade-out, aren't using all 16-bits. The problems come when you re-amplify it. And since you seem to have "excessive" analog gain it COULD be a concern.

Note that analog volume control isn't "perfect" either... You tend to loose signal-to-noise ratio and even if signal and noise are reduced together, when you re-amplify the amplification stage adds its own noise. So again, the loss of resolution sounds like noise (if you can hear it).




* Low resolution is heard as quantization noise. If you make an (normal full volume) 8-bit file in Audacity you can hear it. It's like a "fuzz" riding on-top of the signal and like analog noise it's most noticeable with quiet sounds, but unlike analog noise it goes-away completely with digital silence. (If you experiment with Audacity, be sure to turn-off dither.)
 
OP
Y

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
Line level isn't well controlled/calibrated in home equipment... Usually the output has plenty of signal, and the amplifier has plenty of gain, so you can get full-power from the amp when you turn it up and "everything works OK".


Most SPL meters are A-weighted which is NOT what you want.


Yes, but it may not be that bad... When you reduce the volume digitally you aren't using all of the bits. With "normal" digital attenuation it's not a problem because you can get-down to where you are only using a few bits and at that point you can't hear much of anything so you can't hear the loss of resolution.* Quiet parts on a CD, or the fade-out, aren't using all 16-bits. The problems come when you re-amplify it. And since you seem to have "excessive" analog gain it COULD be a concern.

Note that analog volume control isn't "perfect" either... You tend to loose signal-to-noise ratio and even if signal and noise are reduced together, when you re-amplify the amplification stage adds its own noise. So again, the loss of resolution sounds like noise (if you can hear it).




* Low resolution is heard as quantization noise. If you make an (normal full volume) 8-bit file in Audacity you can hear it. It's like a "fuzz" riding on-top of the signal and like analog noise it's most noticeable with quiet sounds, but unlike analog noise it goes-away completely with digital silence. (If you experiment with Audacity, be sure to turn-off dither.)
Than subwoofer analog gain will be a concern when i loose resolution as it will RE amplify
 

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,757
Likes
5,918
Location
PNW
On my consumer subs with plate amps 1/4 gain is not particularly unusual to match up with other gear.....but hard to know at what spl he's calibrating.....
 
OP
Y

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
MR4 = -10dBV input = 0.3V the DAC is 2V out.
I suggest to use the D30 DAC in re-amp mode and set the output to -16dB
Set the sub level to match the speakers.

For a rough SPL estimate use a smart phone. The Apple ones seem to be fairly accurate.

If i am trying to achieve 80db for speakers and 77 db for sub, is "-16dB" important?
 

Eetu

Addicted to Fun and Learning
Forum Donor
Joined
Mar 11, 2020
Messages
763
Likes
1,180
Location
Helsinki
A DAC with digital volume control would work in a similar way than the software volume control, you would still 'lose bits'. Since the volume control is 32 bits I wouldn't worry about it too much. I would just turn down the software volume until you get a usable range on the sub. I use Equalizer APO (see this thread) to set the negative 'preamp' gain.

I had a look at what settings are available on the Temblor sub. Are you saying that if you turn the sub's input gain down to -30dB there's suddenly no sound? I would have assumed it doesn't mute, only attenuate.
 

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,891
Likes
35,912
Location
The Neitherlands
If i am trying to achieve 80db for speakers and 77 db for sub, is "-16dB" important?

Just set the volume so the speakers can get a sufficiently loud level on the speakers (sub off).
Then set the volume on the sub so it is at the correct level.
Don't worry about the settings/numbers.
Then you can measure the overall volume using the meter. Therein lies the difficulty. 77dB average ? 77dB peak ? this will all be recording dependent.
 
OP
Y

yigitboy

Active Member
Joined
Jan 17, 2019
Messages
143
Likes
28
Location
Turkey
A DAC with digital volume control would work in a similar way than the software volume control, you would still 'lose bits'. Since the volume control is 32 bits I wouldn't worry about it too much. I would just turn down the software volume until you get a usable range on the sub. I use Equalizer APO (see this thread) to set the negative 'preamp' gain.

I had a look at what settings are available on the Temblor sub. Are you saying that if you turn the sub's input gain down to -30dB there's suddenly no sound? I would have assumed it doesn't mute, only attenuate.
Sorry for misunderstanding. In fact it is very difficult to set the volume precisely in the lowest clicks. Sound pressure quickly drops in the last quarter of the gain knob.
Maybe i need a source whose line output is less than 1volt
 
Top Bottom