Adam Sub7 - a few measurements

[dominikz]

For a while now I've been thinking about adding a sub to my desktop system based around the Neumann KH120A. My primary motivation was not to get more LF extension (in the nearfield KH120 go relatively deep for the size), but to solve the bass dips in the 70-110Hz range caused by loudspeaker positioning. Here's an in-room MMM measurement response of the KH120 with 3-band PEQ for room correction:

You can see I had usable bass down to almost 40Hz, but a lot of energy was sucked out around 70Hz and 95Hz due to SBIR. Bass guitars were suffering and I with them
I knew I could probably fix this with a subwoofer, given that I could place it differently than the monitors.

Since I don't have a lot of space, I decided to look for a small sub with auto-off functionality. The 7" Adam Sub7 seemed to fit the bill nicely and I found a B-stock at Thomann that I just couldn't pass by

Given that there's not a lot of data on this sub on the web, I thought to provide some basic measurements. No proper CEA-2010 here though, unfortunately

Nearfield port+woofer FR measurement with highest setting of the LP filter seem to indicate the frequency response is:

• -3dB points: 37Hz-143Hz
• -6dB points: 35Hz-157Hz
• -10dBpoints: 33Hz-180Hz

The manufacturer states 32 Hz - 150 Hz in the specs, and specifically state 32Hz as the -3dB point on the product page.

Next I was interested whether running the monitors from the sub's satellite out would degrade the signal. Here's what RMAA said (direct analogue loopback of my RME Babyface compared to having the sub in the loop, with and without 85Hz high pass):

We see there is around 6dB noise penalty and a significant increase in THD and IMD.
However the worst penalty is on crosstalk (I guess as expected):

Here's the frequency response comparison:

Notice that engaging the 85Hz HP filter seems to add a tiny bit of gain.

The satellite out 85Hz HP filter slope seems to be 24dB/oct:

Let's see the satellite output distortion spectrum (with 1,7Vrms / 7dBu input):

Not terrible, but degraded somewhat vs RME baseline (link to reference).

Lastly, here's the in-room response I was able to get after integrating the sub with my monitors. I got the best results when I pushed the sub to the corner of the room, below my desk. The LP filter is set to 85Hz, monitors are connected to the satellite output and 85Hz high-pass is enabled, sub phase is not inverted. RME Totalmix 3-band PEQ is used to fix a few strong bass resonances (on the stereo out). Response would look nicer with individual EQ corrections for each channel and more bands of PEQ - but this is more convenient and sounds good to me

As you can see, I gained just a little more bass extension, but there is much less loss of energy in the 70-110Hz range. Here's a before and after comparison:

Since the sub and HP filter are footswitchable I was able to A/B test both configurations (not blind, though) and I find the difference very audible; subjectively I feel it very much improved my enjoyment when listening to music.

 

[YSC]

a sub do actually add the lower octave more felt and always welcomed, but somehow comparing the sub7 extension I am surprised that it only extend to in room only to around 40hz, the spec of in room flat to 32hz makes me feel it could extend deeper than the 7040A I owned, but seems it somehow goes 10hz less extended.

 

[Mario Sanchez]

Well, there's only so much a 6.5/7 inch driver in a compact(relatively speaking) cabinet can do in terms of bass output. The "in room" rating probably has it laying in a corner near all three boundaries, which should lend some gratuitous room gain at the lower octave, but then again, ADAM isn't the only sub that gets this boost.
Now now, if only we can see how far we can push this little sub before it cracks...

 

[Recluse-Animator]

77 of these and your good to go.

 

[dominikz]

a sub do actually add the lower octave more felt and always welcomed, but somehow comparing the sub7 extension I am surprised that it only extend to in room only to around 40hz, the spec of in room flat to 32hz makes me feel it could extend deeper than the 7040A I owned, but seems it somehow goes 10hz less extended.

I was also surprised by the modest low frequency extension, but realistically I find mid thirties range sufficient for most music I listen to. For comparison, in another system I use a SVS SB 1000 that goes down to the low twenties in my room, but I can't say that makes a big difference with most music content (there are exceptions, of course).

Regardless, I find the bass response is much improved with the Sub7 as there's no wide nulls in the IMHO very important 60-120Hz range anymore.

Well, there's only so much a 6.5/7 inch driver in a compact(relatively speaking) cabinet can do in terms of bass output. The "in room" rating probably has it laying in a corner near all three boundaries, which should lend some gratuitous room gain at the lower octave, but then again, ADAM isn't the only sub that gets this boost.

Interestingly, mine is also near a corner but doesn't get a lot additional extension from that. Perhaps the -10dB point was somehow misprinted as -3dB in the specs?

Now now, if only we can see how far we can push this little sub before it cracks...

It is unlikely I will be in a position to test for this, but would be interesting to see - I agree

77 of these and your good to go.

 

[TrevC]

I have one of these. BK XLS200
No contest.

 

[dominikz]

I have one of these. BK XLS200
No contest.

I have no doubt - it is a bigger box and bigger woofer compared to Adam Sub7.
However I was looking for something small in this system and was willing to sacrifice extension and SPL capability.

 

[YSC]

I was also surprised by the modest low frequency extension, but realistically I find mid thirties range sufficient for most music I listen to. For comparison, in another system I use a SVS SB 1000 that goes down to the low twenties in my room, but I can't say that makes a big difference with most music content (there are exceptions, of course).

Regardless, I find the bass response is much improved with the Sub7 as there's no wide nulls in the IMHO very important 60-120Hz range anymore.

Interestingly, mine is also near a corner but doesn't get a lot additional extension from that. Perhaps the -10dB point was somehow misprinted as -3dB in the specs?

It is unlikely I will be in a position to test for this, but would be interesting to see - I agree

just checked, weirdly the spec of Sub7 is 32hz -3db, so it should be similar to the 7040A, I am using it right on the front wall in between the main speakers, and it goes flat to 30hz and -3db @28hz, the Sub 7 should fair a bit better, but as you said, music alone it's good enough

 

[nat1]

I was also surprised by the modest low frequency extension, but realistically I find mid thirties range sufficient for most music I listen to. For comparison, in another system I use a SVS SB 1000 that goes down to the low twenties in my room, but I can't say that makes a big difference with most music content (there are exceptions, of course).

Regardless, I find the bass response is much improved with the Sub7 as there's no wide nulls in the IMHO very important 60-120Hz range anymore.

Interestingly, mine is also near a corner but doesn't get a lot additional extension from that. Perhaps the -10dB point was somehow misprinted as -3dB in the specs?

It is unlikely I will be in a position to test for this, but would be interesting to see - I agree

Is there any obvious distortion or downgrade in sound quality compared to the SB1000 in the 40hz and above range? I want to add a subwoofer to my LSR305's for a similar reason, to fill in a huge null in the 45-70hz region in my room and I am not concerned about extra bass extension.

 

[dominikz]

Is there any obvious distortion or downgrade in sound quality compared to the SB1000 in the 40hz and above range? I want to add a subwoofer to my LSR305's for a similar reason, to fill in a huge null in the 45-70hz region in my room and I am not concerned about extra bass extension.

Well I'd bet SB-1000 can also go significantly louder than the Sub7 - but this I haven't tested as I don't listen very loud.
With good integration and room EQ, and at the levels I use, the audible difference between the two IMHO boils down to bass extension. I haven't noticed any sound quality issues with either sub.