• 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!

exploring why my NHT SuperZeros don't sound great

Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
I've ordered better speakers to replace these 1991 SuperZeros. But I would still like to learn how to understand these measurements. The lack of bass in the SuperZeros (with the subwoofer off) is much more evident from listening than it would seem from these graphs.

In this graph I'm comparing the SuperZeros (orange) to the iMac Pro's built in speakers (blue). The SuperZeros sound better in some ways, but also a bit shrill... and definitely short on bass. Turning on the subwoofer obviously helps, but there's still something missing in the sound.
Screen Shot 2021-06-12 at 3.12.08 PM.png
 
Last edited:

Beershaun

Major Contributor
Forum Donor
Joined
Oct 3, 2019
Messages
1,864
Likes
1,910
Ouch. You are correct there. You have some massive dips in the mid bass and midrange region. I think you want you frequency response to vary less than +/-3db and I see huge swings and dips of 10 to 20db. So that you will definitely hear as mid bass and midrange suck out.
 
OP
S
Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
Ouch. You are correct there. You have some massive dips in the mid bass and midrange region. I think you want you frequency response to vary less than +/-3db and I see huge swings and dips of 10 to 20db. So that you will definitely hear as mid bass and midrange suck out.
Do you predict changing to fuller-range main speakers will fix more than half of this? Or are room issues the bigger culprit?
 

Beershaun

Major Contributor
Forum Donor
Joined
Oct 3, 2019
Messages
1,864
Likes
1,910
Do you predict changing to fuller-range main speakers will fix more than half of this? Or are room issues the bigger culprit?
We need more info from you on your listening room and distance. Are you at your desk in your office within 3 feet of your speakers or sitting on the couch 7-12 feet from them in a big room?
Either way check out the link in @MZKM signature and find 3 speakers in your price range with the highest preference score without sub and take a look at them.
 
OP
S
Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
We need more info from you on your listening room and distance. Are you at your desk in your office within 3 feet of your speakers or sitting on the couch 7-12 feet from them in a big room?
Either way check out the link in @MZKM signature and find 3 speakers in your price range with the highest preference score without sub and take a look at them.

This is at a desk a bit less than 1 meter from the speaker in a carpeted home office 11'x13'x9' (3.4m x 4m x 2.7m). I typically listen with a subwoofer crossed at 100Hz, switched off during that measurement. Speakers are a couple inches above ear height, 20 inches (50cm) from the back wall. No room treatment yet.

I have ordered a pair of Genelec 8341a but not sure when they will arrive.
 

alex-z

Addicted to Fun and Learning
Joined
Feb 19, 2021
Messages
910
Likes
1,684
Location
Canada
The lack of bass is totally expected given the small woofer + sealed cabinet. One of the rare speaker designs that needs a subwoofer crossover as high as 150Hz, and not all subs will play that high happily.

The dip from 2500-6500Hz is bigger than expected. So you either have a measurement issue or some sort of setup issue causing that.

The rise in treble after 8000Hz is expected when using these near-field, EQ that down.
 
OP
S
Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
The dip from 2500-6500Hz is bigger than expected. So you either have a measurement issue or some sort of setup issue causing that.
Hmmm... I'm using a dbx A-256 which was described at the time as a flat reference microphone. I haven't found its specifications though. I wonder if that could be throwing off the measurement.
 

SIY

Grand Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
10,383
Likes
24,749
Location
Alfred, NY
These NEED to be used with a subwoofer.

The midrange suckout is remarkably easy to hear on pink noise. That's fixable with some crossover work.
 

wwenze

Major Contributor
Joined
May 22, 2018
Messages
1,284
Likes
1,827
I'm more interested in the iMac Pro's internal speakers having more bass than an Audioengine A2...

Also the curve of the iMac looks like it follows the same shape as the superzero so I suspect the mic. Try 1/1 octave smoothing and see what happens.
 

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
I just wouldn't expect much from those speakers alone. In a small room with subs perhaps....don't do any nearfield listening tho.
 
OP
S
Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
OK, I have another pair of NHT SuperZeros. This one (green) doesn't show that weird dip around the 4K mark. Does this suggest the mic is OK? Unlike the speakers, the mic spent most of its life in a padded box.
Screen Shot 2021-06-12 at 7.30.39 PM.png
 
OP
S
Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
I'm more interested in the iMac Pro's internal speakers having more bass than an Audioengine A2...
Sorry, I didn't have the absolute SPL calibrated on that take. I cranked up the mic gain to make the comparison easier.

1/24 smoothing is too fine grained? I didn't know which was the octave setting. Would that be 1/1?
 

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
What's the background of each measurement to make them comparable?
 

alex-z

Addicted to Fun and Learning
Joined
Feb 19, 2021
Messages
910
Likes
1,684
Location
Canada
OK, I have another pair of NHT SuperZeros. This one (green) doesn't show that weird dip around the 4K mark. Does this suggest the mic is OK? Unlike the speakers, the mic spent most of its life in a padded box.

The original pair (orange) might have some crossover damage, because the second pair(green) far more closely matches what amir measured in his review. Was anything else changed, or did you swap the speakers into the exact same spot, and use the same mic location?

Edit: Are you using a calibration file for your mic? Ideally you want a calibration for your specific mic, but a generic one is better than nothing.

https://www.hometheatershack.com/threads/dbx-rta-m-mic-anyone-use-this.57980/
 
OP
S
Joined
Jun 5, 2021
Messages
54
Likes
39
Location
Seattle, WA
The original pair (orange) might have some crossover damage, because the second pair(green) far more closely matches what amir measured in his review. Was anything else changed, or did you swap the speakers into the exact same spot, and use the same mic location?
Sorry, there were many variables in that previous comparison, including the locations and different versions of the SuperZero (the sharp-cornered bookshelf version vs. the injection-molded wall mount version).

Here's a test of two different bookshelf SuperZeros with all positions the same. The orange one is the one you already saw that you suspect is damaged. The blue one is the other one of the same pair, purchased at the same time and used the same way. I am still not sure what smoothing setting to use, so I set that to 1/12. Does that mean 1/12 of an octave -- i.e. half steps on a piano?
Screen Shot 2021-06-13 at 12.35.16 PM.png



Edit: Are you using a calibration file for your mic? Ideally you want a calibration for your specific mic, but a generic one is better than nothing.

I have not been able to find a calibration file for my dbx a-256. It's kind of irritating that I stored this for years in the hopes it would be useful, only to find no one supports it when I want to use it again. It looks like I should find a UMIK-1, or other supported measurement mic? Amazon is out of stock. I do have an old Radio Shack sound level meter.
 

alex-z

Addicted to Fun and Learning
Joined
Feb 19, 2021
Messages
910
Likes
1,684
Location
Canada
Sorry, there were many variables in that previous comparison, including the locations and different versions of the SuperZero (the sharp-cornered bookshelf version vs. the injection-molded wall mount version).

Here's a test of two different bookshelf SuperZeros with all positions the same. The orange one is the one you already saw that you suspect is damaged. The blue one is the other one of the same pair, purchased at the same time and used the same way. I am still not sure what smoothing setting to use, so I set that to 1/12. Does that mean 1/12 of an octave -- i.e. half steps on a piano?.

If both speakers come from the same pair, one definitely has some sort of problem. The blue line is what is expected.

The smoothing doesn't matter too much. In terms of what we hear, psychoacoustic is the closest, although I usually measure in 1/12 or 1/24 to avoid masking minor issues like baffle diffraction.

Yes, it refers to octaves. 1/1 smoothing would be averaging an entire octave.
 

AnalogSteph

Major Contributor
Joined
Nov 6, 2018
Messages
3,334
Likes
3,278
Location
.de
Here's a test of two different bookshelf SuperZeros with all positions the same. The orange one is the one you already saw that you suspect is damaged. The blue one is the other one of the same pair, purchased at the same time and used the same way. I am still not sure what smoothing setting to use, so I set that to 1/12. Does that mean 1/12 of an octave -- i.e. half steps on a piano?View attachment 135424
That very much looks like a bad capacitor in the crossover's highpass leg, as previously suspected (presumably a small electrolytic, expect somewhere around 5 µF). Much diminished capacitance and high ESR would yield exactly that kind of difference. A 6 dB upper midrange and treble dip is pretty yikes.

This may be worth investigating further if you're stuck with these for a while longer. Parts cost itself would be quite negligible.
have not been able to find a calibration file for my dbx a-256. It's kind of irritating that I stored this for years in the hopes it would be useful, only to find no one supports it when I want to use it again.
No biggie. These kinds of electret measurement mics tend to be decently accurate up to several kHz as-is. You can see the spread across hundreds of samples here, for example:
https://www.hifi-selbstbau.de/grund...0-1000-mikrofonkalibrierungen-eine-uebersicht
Also, you can get the microphone newly calibrated if it is of decent quality to begin with (these things aren't exactly being reinvented all the time). Having both 0° and 90° measurements made is recommended, it'll give you more flexibility. Look for a service geared towards hobbyists like us, you obviously don't need lab grade calibration and it could get a bit expensive otherwise.
 
Top Bottom