NOOB questions about subwoofer calibration

[john_dikeman]

I'm new to the subwoofer world. I recently found an old SVS 20-39 PC + locally that was quite cheap. I'm running it 2.1 with an Arcam A18 FMJ and Focal Aria 906 Aria speakers.
I also found an anti-mode 8033 locally very cheap.

In general I'm extremely happy with it but you know how rabbit holes are. I'm now curious how much better I can make it with what I've already got. This is all probably way overthought....

Couple things, it's in the corner of the room, to the left of the left speaker. I can't move it. I'm lucky my girlfriend hasn't kicked me and it out the window already...

I've currently got it set to 12 hz and the ports all plugged as someone at SVS suggested for optimal transient response.

I did a few things to try to integrate it but I did not measure it with a proper spl meter, instead with my phone with the Decibel X app. I used test sine waves to measure from my seating position and found that getting the gain for the bass to similar gains from the speakers in mid frequencies resulted in the bass being way too loud. Is it safe to assume my phone simply can't measure bass SPL properly? Or, do I just prefer less bass? I think the point at which it would register equal to the spl of the speakers, the house would be shaking and neighbors would be complaining...
I'm trying to remember an EQ curve that is commonly used for headphones, someone help me here... Is there something similar for a hifi system? Do you actually want flat response from 20 hz to 20,000?

At this point I'm flat broke so I can't really afford an SPL meter, and in the end I think fine tuning by ear is going to win out anyway, but I am curious still...
I do have the mic that came with the anti-mode 8033, which I'd assume is good for measuring bass levels as that's what it's made for, and I also own an SD Systems condenser microphone which isn't entirely flat but I have a chart which shows it's dips. That and a good audio interface and Reaper.

I've also been experimenting EQing from my laptop using the APO equalizer.

Anyway, any suggestions for fine tuning are most welcome!
And room correction, which would probably help more than anything, isn't really an option right now either...

Thanks!

 

[ski2xblack]

So you're calibrating by ear.

Corner placement of the sub has some considerations. It will result in considerable boundary reinforcement. If you can configure the SVS, you don't want to target a low f3. A higher f3 and gentler roll off (sealed) typically works better, as the subs roll off on one hand and cabin gain on the other result in deeper realized response. The inherently deeper digging configurations of the SVS will be relatively bloated and overwhelming when corner loaded.

And the sub's gain setting will be on the low side, again related to cabin gain/boundary reinforcement. Corners = 1/8 space, so the db gains are significant.

Corner placement in enclosed rectangular rooms will have more pronounced room modes. Irregular, open floorplan rooms are less afflicted.

Good luck, and keep asking questions.

 

[Pandaman617]

Hey John, I’ve got an extra UMIK-1 that’s on loan at the moment but once I get it back I could send it your way if you would like. Than you can get involved with REW, possibly MiniDSP if you wish as well as MSO.

 

[john_dikeman]

Hey John, I’ve got an extra UMIK-1 that’s on loan at the moment but once I get it back I could send it your way if you would like. Than you can get involved with REW, possibly MiniDSP if you wish as well as MSO.

Ah that's very kind of you. Where do you live? I'm in Belgium.

 

[Pandaman617]

Ah that's very kind of you. Where do you live? I'm in Belgium.

I’m in Massachusetts in the good old United States. I would imagine shipping wouldn’t be too horrible as it’s a very light package. I’ll look into it when I get out of work today.

 

[john_dikeman]

Hmm, I just fear it could get stuck in customs. Lately they changed EU customs regulations. Or they might charge me 50 euros tax on it. So I'd probably be better off finding one used over here.
But thanks for the offer!

The mic I have is this one:

LCM85 for Wind and Brass instruments

SD Systems SDSystems Webshop Microphones for saxophone mikes clip-on clipon clipon saxmic flutemic

store.sdsystems.com

It's a very good and sensitive mic, but I can imagine that since it's cardioid-unidirectional not omnidirectional that could be problematic. It's made to be clipped on to my saxophone, not sure if it would be helpful testing sound in the middle of a room.

Any thoughts?

 

[William Lemmerhirt]

Hey John, I’ve got an extra UMIK-1 that’s on loan at the moment but once I get it back I could send it your way if you would like. Than you can get involved with REW, possibly MiniDSP if you wish as well as MSO.

Just wanna say, that is very nice of you to do that. Bravo!

Also I think the advice by svs is wrong. The 12 and 16hz settings on that subwoofer require one or two of the plugs to be in place based on which setting, or you could damage it. It also sets the subsonic filter and changes the output curve of the amp.
Do you still have the port plugs?

 

[john_dikeman]

Just wanna say, that is very nice of you to do that. Bravo!

Also I think the advice by svs is wrong. The 12 and 16hz settings on that subwoofer require one or two of the plugs to be in place based on which setting, or you could damage it. It also sets the subsonic filter and changes the output curve of the amp.
Do you still have the port plugs?

Ah yes, I have all the ports plugged while on the 12hz setting. It's my understanding, though I could be wrong, that it's fine to have everything plugged for any setting, it's just problematic going the other way, tuning to 12 or 16 with them all open.

 

[Pandaman617]

Honestly, mic’s aren’t my speciality but I would assume if you had a 90 degree calibration for it, it would work well? I’m honestly not sure, there’s plenty of guys on here with exponentially more knowledge of microphones than myself and I don’t want to steer you in the wrong direction. Bummer about customs! But I totally understand!

 

[William Lemmerhirt]

Ah yes, I have all the ports plugged while on the 12hz setting. It's my understanding, though I could be wrong, that it's fine to have everything plugged for any setting, it's just problematic going the other way, tuning to 12 or 16 with them all open.

I believe you’re correct. But I read the OP and iirc you said you had it in 12hz with all ports open. Forgive me if I misread that. Also I think for 12hz you want one port open, not all ports plugged. However I don’t think you’d damage it as such, and considering that it seems like it’s bass heavy, running it sealed might be best although I’m not a fan of that personally.

Curious. Did svs actually tell you to leave all ports open with 12hz setting? Or did I misread that? Anyways have fun with it. It’s an old sub, but still very capable and special.

 

[john_dikeman]

I believe you’re correct. But I read the OP and iirc you said you had it in 12hz with all ports open. Forgive me if I misread that. Also I think for 12hz you want one port open, not all ports plugged. However I don’t think you’d damage it as such, and considering that it seems like it’s bass heavy, running it sealed might be best although I’m not a fan of that personally.

Curious. Did svs actually tell you to leave all ports open with 12hz setting? Or did I misread that? Anyways have fun with it. It’s an old sub, but still very capable and special.

No I miswrote. I meant that I was running it on 12 hz with all ports plugged.
I think I just typed "with all ports"... I fixed it now.

But yes, SVS suggested for hifi musicality and clarity that was the best setting. I also initially assumed 25 hz would have been better.

 

[john_dikeman]

Honestly, mic’s aren’t my speciality but I would assume if you had a 90 degree calibration for it, it would work well? I’m honestly not sure, there’s plenty of guys on here with exponentially more knowledge of microphones than myself and I don’t want to steer you in the wrong direction. Bummer about customs! But I totally understand!

Yeah, maybe it's naive of me, but if I just set it up in listening position facing forward the way my face would be.... Wouldn't that work?
I can always try it... REW is free eh? Might as well give it a go.

 

[john_dikeman]

Ok, I haven't tried REW yet but I have been comparing the settings 12 hz vs 25hz. It seemed logical to me that 25hz would be better for music, and ski2xblack seemed to suggest that as well. However, It plays noticeably cleaner in 12 hz mode. Which is what the SVS guy told me. And I remember now, in the manual, or somewhere in the SVS literature, it explained that 12hz was better for music as it had a smoother curve down to 12 hz as opposed to say 20hz which dropped off at 20hz but also had a higher SPL at 20hz. It said if you want dramatic, big, house shaking bass use the higher setting.

 

[Pandaman617]

Yeah, maybe it's naive of me, but if I just set it up in listening position facing forward the way my face would be.... Wouldn't that work?
I can always try it... REW is free eh? Might as well give it a go.

You do generally want it facing at a 90 degree angle but again don’t quote me on that I’m no expert

 

[ski2xblack]

Hopefully you'll get ears on in the form of REW measurements soon to see what's really going on.

A few other general thoughts...

You need to differentiate specs/ground plane measurements from those of your own in-room response target, accounting for the sub's acoustic roll-off and the gain resulting from corner placement. The SVS in one configuation may be flat to subsonic territory in a ground plane measurement, but put it in a corner and it will have a dramatically rising response as frequencies decrease, which will require attenuation/eq to bring back into line. If it were me, I would choose the configuration of the SVS that yielded the best compromise between extension and flat in-room response *without requiring additional eq*. Armed with REW, that won't be guesswork, and it will help you choose the appropriate config for your particular room, whatever it ends up being.

There isn't really any musical content at 12hz. There is music content where your sub and mains cross, so getting that area correct is somewhat more consequential to your ear's enjoyment than a few hz of extension on the low end. Using REW you'll be able to dial in the sub-to-mains crossover far better than by ear, getting you closer to optimum level matching, crossover frequency, and phase adjustment.

*target response curve...you had asked previously if flat response is what to aim for. I think it is, at least for system calibration purposes (optimizing speakers/sub response in situ) and for the sake of accuracy. Once the subs are properly integrated with the mains, *then* global eq can be added for preference. Global eq won't scramble your REW efforts with the sub-to-mains crossover, but merely goosing the sub level independantly of the mains will.

In room measurements are typically a real mess, fair warning.

Are you using the antinode thingie? It seems a bit limited if it's only used on the sub, and could add latency due to the ad/da conversion. The Arcam has no bass management facilities at all, does it?

 

[john_dikeman]

ski2xblack

Thanks, that's a lot of info to work through.
I'll let you know when I get REW up and running, I'm starting to realize that will be a whole process figuring out how to use it and utilize the information. So it'll probably have to wait a bit. Need to find a day with nothing to do and no one home.

However, you touched on one question I had which is namely, what good does full calibration with REW do if I can only control gain and crossover of the sub? Though, from what you're saying getting an accurate crossover frequency can already do a lot. And I've got the tuning options I can test as well...
Is it possible to to make adjustments with REW? Of course, in that case it's only effective when playing music from my computer, which is a lot of the time...

To answer you question, no the Arcam does not have any controls other than the most basic options to turn "bass" up or down across the entire output.

I am using the antimode at the moment. My understanding is that all it does is eq the sub itself to get it as flat as possible from the position of the listener. To my ears it's helped. And according to my bad decibel app, it is much flatter than without. Their literature says:
"The 8033 has insignificant delay of 2.7ms which is inaudible at low frequencies. For comparison, the additional delay of room modes can be more than 500ms, which is eliminated by Anti-Mode correction."
I also found it funny. They suggest simply moving the sub (i forget how far, 90cm?) closer to the listener to compensate. However, before that they mention it doesn't matter so much where you put the sub. If moving it 90cms changes the timing, I'd think it would matter a great deal where you put it....

 

[ski2xblack]

You're correct about the inability to export and apply peq curves from REW with your current kit. Fortunately, your Focals don't really need eq. They also seem sensibly designed to be used with a sub from the start, no bass peak or overly ambitious extension. They should pair quite nicely with the SVS with minimal fuss. The anti-node should provide the eq in the frequencies where your system needs it most. (It's pretty common in rigs with well sorted speakers to only use eq below the room's Schrader frequency, where room modes dominate. Granted, the antinode won't "correct" anything the speakers do below your room's Schrader freq, but it will for the sub's band.)

REW can still help you empirically verify that levels, crossover freq, and phase settings on the sub are correct. Calibration is a "set and forget" one-time thing, until you switch rooms or move stuff around. You should be able to get as smooth of a mains/sub blend as Audyssey can pull off.

A cautionary note, probably unnecessary given the non-headbanger kit, but worth considering. You will be feeding your speakers a full range signal. They roll off steeply at 80 hz. Below that, the drivers and port go out of phase. When they receive content below that, it will result in excessive cone motion. Is that a problem? Probably not, as long as you're not blasting it. But if you do blast it, it will increase IM distortion and put you at risk of discovering the driver's mechanical limits, obviously something you want to avoid!

That's all I have for now, I'm headed off to ski.

 

[john_dikeman]

Great, that all makes a lot of sense.
Curious to try it out now.

Enjoy the snow!