REW and "Sub" Integration - what's your take?

[bogart]

A friend had an extremely cheap "subwoofer" going spare in his basement and suggested I try using it with my desktop speakers (Era Design 5). I'm using miniDSP 2x4HD to do crossovers and such, but tried 'wide open' measurements on L, R and sub. I matched the sub to the speakers by ear, and we're not measuring super loud here. Microphone position was roughly head position seated at the desk, <1m from all drivers.

As I look at these measurements, I see very little 'subwoofer' content at all. I'm not certain the degree to which the room is affecting these, but I am missing a fundamental tone from the sub until closer to 50Hz.

By ear, the let's-call-it-a-bass speaker does seem to dig deeper than the satellites, but REW reports no fundamental tone but lots of harmonic distortion at lower frequencies. This definitely "thickens up" the bass in the 50-60hz range, but I'm debating whether or not this is a useful contribution.

"Bass speaker" distortion plot here:

Left Desktop Speaker Distortion Plot:

Red trace below is Sound & Vision quasi-anechoic response for the desktop speakers, which seems fairly well represented particularly in the blue trace above.

Bottom line question is: does this free bass speaker have any utility? It does appear to make some noise, but does it contribute anything beyond noise to try to integrate it?

 

[Another Bob]

I think you've pretty much answered your own question. The sub is contributing little but noise, at least as you have things currently positioned. Not unusual for a very cheap sub. However, don't underestimate the effects of room position. Try the sub in a different location or two before giving up. Note that your L/R speakers have almost 8 dB difference in volume at 90 Hz in your measurements, which is almost certainly due to them having different distances to the walls of your room.

 

[bogart]

Thanks, @Another Bob for nodding along with this one. It's honestly kind of funny how little 'real' output there is with this guy. I was anticipating it skewing toward higher frequency output closer to intended crossover (so was going to look at the output/distortion tradeoffs with satellites when figuring a crossover) but had to laugh when I saw these plots. Good suggestion to try moving the physical location of the sub. It's a little bit tight quarters but can definitely play with that. It's also ported (that's how it gets so low! ) and I may try blocking those too.

I think that the left speaker is getting a cancellation at 90 as it's tucked under an eave and close to a wall - probably nothing to be done to improve that one.

 

[D!sco]

Cheap subs are really bass boost drivers for cheap satellites. Getting down to 50hz is probably all you should expect at certain volumes. This being based only on what we see of your ‘cheap sub’. More info might be helpful, ported vs sealed and box/driver size would be great. But even with EQ, you should only expect so much.

 

[mdsimon2]

Not saying this is the case but assuming you are I running Windows I would make sure that you do NOT have Audio Enhancements enabled.

UMIK-1 + Windows Audio Enhancement

Dear All, We've heard from some of you that Windows update is enabling Audio Enhancements on microphone inputs by default for their new builds. Features like...

www.minidsp.com

I've seen many cases where the low end appears to drop off in measurements as a result of this setting being enabled.

Michael

 

[bogart]

Cheap subs are really bass boost drivers for cheap satellites. Getting down to 50hz is probably all you should expect at certain volumes.

This is a really good way of putting it, and I am probably going to shamelessly copy that phrasing when telling my friend how it's working. The fact that it goes "boom" and "thud" doesn't necessarily add anything useful that better (bigger) speakers can't.

It's a ported box of approximately 16x14x12.5" dimensions housing a 9" driver, so physics certainly aren't on our side here for very low frequency outputs.

 

[D!sco]

I'm surprised a 9" is behaving so poorly. It being ported probably won't help any amount of bass boost, I wouldn't be surprised if they tuned the enclosure to boost at 50 and cut.

 

[bogart]

Not saying this is the case but assuming you are I running Windows I would make sure that you do NOT have Audio Enhancements enabled.

UMIK-1 + Windows Audio Enhancement

Dear All, We've heard from some of you that Windows update is enabling Audio Enhancements on microphone inputs by default for their new builds. Features like...

www.minidsp.com

I've seen many cases where the low end appears to drop off in measurements as a result of this setting being enabled.

Michael

Super interesting catch, and not one I had considered checking for! At your suggestion, I did find 'enhancements' were ticked on for the UMIK - looks like I need to re-measure!.

My work computer also runs some garbageware WAVES | MaxxAudio Pro software by default, and that is the one I used for REW since it's the source for the music playback. Unfortunately without admin rights I can't remove it, so I may be stuck regardless - I'll look back through to make sure it doesn't have any suspicious settings on for "small speakers" or something.

 

[abdo123]

Feel free to head to this thread and check the subwoofer integration process i went through with another member. It’s very thorough.

Speaker placement and subwoofer integration for a small living room using MiniDSP SHD + REW

Hey everyone! First, I want to give a big thanks to everyone for helping me get this far-- there's an overwhelming amount of info online for integrating subs into a 2.2 system, both in general knowledge and program interface navigation for testing. The below is what I've learned through the...

www.audiosciencereview.com

 

[bogart]

Bravo to @mdsimon2 for diagnosing this patient so well, and to @D!sco 's intuition that a 9" should do better than what the initial measurements showed! Both were right. Advanced settings were on for the microphone, hobbling its low-end badly (I guess that's "wind noise" or rumble filtering?) - it's night and day different here. The left speaker is definitely resonating more in the 30-200Hz range and can be tamed with EQ, but most reassuringly the subwoofer now plays frequencies it's supposed to, and it looks useful to go from say 20-50Hz where the speakers won't.

Further, when it does make sounds, it appears not to be exclusively a distortion-generator. It's coming in a little hot since I'm summing L+R, so it'll need its level turned down a wee bit. Still, looks like usable response here from 20 Hz up, and probably some room and speaker non-linearities to smooth out from about 30-100. New distortion plot below.

I can't get over the degree to which one hidden little setting just ruined the measurements - crazy! Now I can actually work with this!

 

[bogart]

@abdo123 - I'm working through your suggested approach. I've taken a close-mic woofer measurement with stuffed port, and am wondering whether this is a "close enough" approximation of the driver response to work as you suggest.

This is a BU2 crossover at 90 targeting 102.5 dB. It looks a little high at the lows and a little low at the highs:

Another shot I took was a BE3 at 90Hz targeting 103 dB:

Big picture, it looks like the woofer is a little boosted up to 400 Hz, which may be part of the challenge (20-1,000 trace below, pardon the non-standard axis):

 

[abdo123]

@abdo123 - I'm working through your suggested approach. I've taken a close-mic woofer measurement with stuffed port, and am wondering whether this is a "close enough" approximation of the driver response to work as you suggest.

This is a BU2 crossover at 90 targeting 102.5 dB. It looks a little high at the lows and a little low at the highs:

View attachment 172278

Another shot I took was a BE3 at 90Hz targeting 103 dB:
View attachment 172279

Big picture, it looks like the woofer is a little boosted up to 400 Hz, which may be part of the challenge (20-1,000 trace below, pardon the non-standard axis):
View attachment 172280

Did you do baffle step adjustment? If so it doesn't matter that you get it absolutely exact. As accoustical roll-offs are seldom the same as electrical ones. Do not use BE, only BU so you can stack a BU filter on top and get a LR behavior, like i explained in the thread.

 

[bogart]

Thanks for the quick answer. I did not do baffle step adjustment yet - I wasn't 100% clear on where in the process to do it, so it seems it is before now I should do that and try again, it seems?

 

[abdo123]

Thanks for the quick answer. I did not do baffle step adjustment yet - I wasn't 100% clear on where in the process to do it, so it seems it is before now I should do that and try again, it seems?

Your current measurement is not representative of reality till you do . Without it you’re measuring the driver, not the speaker.

 

[bogart]

Did you do baffle step adjustment? If so it doesn't matter that you get it absolutely exact. As accoustical roll-offs are seldom the same as electrical ones. Do not use BE, only BU so you can stack a BU filter on top and get a LR behavior, like i explained in the thread.

OK! Now we have a BU2 lined up with a baffle-step corrected woofer response. This looks to be a good approximation, so I'm going to proceed using these.

 

[abdo123]

OK! Now we have a BU2 lined up with a baffle-step corrected woofer response. This looks to be a good approximation, so I'm going to proceed using these.

View attachment 172286

Looks better! Can you try the frequency that is at exactly 93.5 dB?

 

[bogart]

Looks better! Can you try the frequency that is at exactly 93.5 dB?

Facilement - here we are. Looks a little tighter in the crossover range but a little more overshoot in the lower frequencies. Probably a better match?

 

[abdo123]

Facilement - here we are. Looks a little tighter in the crossover range but a little more overshoot in the lower frequencies. Probably a better match?

View attachment 172290

Yeah looks better, go with that!

 

[bogart]

Yeah looks better, go with that!

Thanks - now, following your procedure, I should apply a BU2 on top of that for the speaker and I end up with an LR2 effective cross. Then, I'll need to apply the same to the subwoofer.

However, the subwoofer is hardly linear in its response in that range from my listening position measurement - though that surely has room issues included. Should I do a similar close-mic approach (and measure the sub ports and baffle step correct) before applying the crossover and gain-matching? Or just apply the crossover and then see what happens?

 

[abdo123]

Thanks - now, following your procedure, I should apply a BU2 on top of that for the speaker and I end up with an LR2 effective cross. Then, I'll need to apply the same to the subwoofer.

However, the subwoofer is hardly linear in its response in that range from my listening position measurement - though that surely has room issues included. Should I do a similar close-mic approach (and measure the sub ports and baffle step correct) before applying the crossover and gain-matching? Or just apply the crossover and then see what happens?

LR4 not LR2.

And usually you want to do similar measurements for the subwoofer so the (anechoic) volume of the two is equal. I discuss that in the thread i linked. You don’t want the speaker to play louder than the subwoofer or vice versa at the crossover frequency.