Please see attached image of my room layout. After experimenting with the single sub in various locations I found I preferred the near field position for during TV viewing. Unfortunately I was partial to the opposite corner location when listening to music in the adjacent/connected room.... Solution? I bought another sub.
I figured I'd place the subs in both of the locations mentioned above, but after quite a bit of reading I'm concerned about how to optimize them. I have a Denon X1000 with MultiEQ XT, but cannot independently EQ two subs. I've done quite a bit of reading now and understand the prevailing suggestion seems to be to be:
1. Gain match (don't believe this to be required in my case as my subs are the same and I can match the knob locations)
2. Separate subs equally from main listening position
3. Run Audyssey while both subs are connected with a y adapter.
Problem is the positioning I've proposed would leave one sub a few feet from the MLP and the other 15 ft or so away... I'm concerned about time delay, do you think the varying distances will be an issue? I'm very new to all of this, but have done enough reading around here to know testing is paramount so I've ordered an external sound card and a RadioShack sound meter -I'll attempt to test with REW after I've got everything set up. Am still struggling on the best approach for initial setup however.
My current thought process is:
1. Run Audyssey with just the distant sub connected and check indicated distance in the receiver.
2. Re run Audyssey with just the near field sub connected and check the indicated distance.
3. Average the two indicated sub distances and set the receiver to this value.
4. Plug in both subs, play test tone, and change phase on distant sub until SPL reading in the MLP is at it's highest point.
Does the above make sense? I realize it's not ideal, but my gut tells I'm better off letting Audyssey EQ the near field sub and manually assisting with the distance settings as I anticipate that'll be the most difficult part for Audyssey. My guess is both subs will need similar EQ parameters as they should have similar frequency response, although I don't know how much the room could play a factor here... Am wondering if I'd be better off just letting Audyssey try to EQ both subs at the same time but my concern is the varying distances would throw things off.
Thoughts? Any comments or suggestions would be greatly appreciated, and thanks in advance!
If you're not gonna get a MiniDSP, next best is to just let Audyssey EQ them both at the same time...no reason to go through trying to calibrate them separately with Audyssey, it won't help.
You should set phase for highest SPL pre-Audyssey.
You may still benefit from gain matching....not all amp gain controls are exactly the same, even on identical subs.
If you find localization with the near sub being a problem, you can lower the crossover on that sub (to say 40-60hz) and it will help.
MiniDSP is the best option though.
Set the gain on both subs to the same level - around 12:00-2:00 on the gain knob is a good starting point. Set phase to "0" on both subs for now.
1. Connect sub #1 only and place it at the MLP
2. Do the sub crawl to determine the best position for sub #1
3. Place sub #1 in that position
4. Connect both subs and place sub #2 at the MLP (with sub #1 playing as well)
5. Do the sub crawl to determine the best position for sub #2
6. Place sub #2 in that position
7. Playing the AVRs test tone, adjust phase on one of the subs until you get the maximum SPL at the MLP (could be variable or a simple 0/180 switch)
8. Run Audyssey, first mic position only, and "calculate"
9. Look to see where Audyssey has set your sub trim, you want it to be around -5db to -8db ideally
10. Adjust the gain on both subs by the same amount up or down as needed
11. Repeat 8-10 until you get the sub trim around -5db to -8db
12. Run the full Audyssey calibration
13. Bump up the sub trim from 3db to 6db to your preference
Do you think the MiniDSP would provide a noticeable benefit -if so how significant? I don't need things absolutely perfect, but after making the investment in the subs I don't want to have heavily degraded performance because I didn't EQ them properly... Am not sure how much of a sacrifice running Audyssey on the both subs at the same time might be.
Where/how would the MiniDSP fit into the standard set up procedure you outlined?
Which MiniDSP would you recommend?
You would EQ and adjust delay on the MiniDSP post-Audyssey.
That being said, I have had pretty good results with and without the MiniDSP in the chain...there are a few discussions here if you want to search for more detail. You can get both subs in phase with each other with the phase knob/switch on the subs, and in phase with your mains with the distance setting in the AVR, the only added benefit with the MiniDSP is being able to set the delay on the sub that is closer to you. Only you can say how important that is to you.
Basically, once programmed, it goes between the AVR's sub output/s, and the subwoofers. It gets power from USB, I use a USB wall charger to power mine. During setup though and programming, you'll need it plugged into a laptop or other computer, where you should also have the free REW software loaded, and you'll also need a measurement mic like the Umik-1. I paid about $205 for the Minidsp, mic and advanced 2 way plug in. I can almost guarantee that $200 will be the best $200 you can spend to improve your bass response.
It's a great tool for level setting, phase adjustments, delay, and of course the room correction eq via 6 bands of parametric eq on each of the two inputs and all four outputs.
Last edited by 89grand; 08-05-2014 at 02:00 PM. Reason: Said look instead of "tool"...no idea why???
Any other suggestions?
Am I correct in assuming REW will show problems in frequency response if there are issues after using Alan's procedure?
For everyone's benefit (including my own!) I'm linking threads on how to leverage MiniDSP:
Tutorial: Dual sub integration using the MiniDSP
Thanks again for everyone's help!
If you already have a mic, the little over $100 for the Minidsp and plug in is a no brainer in my opinion.
To quote the REW help guide "The Radio Shack meter is perfectly adequate for low frequency room acoustics work"
I had a crazy 32db peak, but that's pretty uncommon. You may end up with pretty decent response. What's really great about the Minidsp, it that you can use it exactly as you want to use it, set what kind of target you want to shoot for, how much boost it can do, within what db of flatness, setup house curves and some other stuff. Audyssey surely is a lot better than nothing at all, and probably gives decent results, but the Minidsp is for more powerful of a tool and doesn't just do what it thinks is best.
I wouldn't use the Rat Shack meter as a mic, but some do. A calibrated UMM-6 or UMIK-1 is the way to go.
Once you measure your room, you're basically screwed until you get the perfect response....at least that's how it's worked for me.
Others forego Audyssey altogether and just use the DSP....to each their own!
I don't see why you don't place the two subs right next to eachother to cure the distance discrepancy. Those other posters and storekeeps which said, "But you want the two differing frequency responses to combine for an overall flatter response so introduce a new one from a secondary room position" were wrong because having a perfectly flat response is a lower priority for you since you have Audyssey XT to EQ the net results with its 512! different control points dedicated to just the bass. [Not to imply you don't want there to be an absence of broad dips which suck up amp power to fix, when EQ'd with complimentary peaks]
THE BIG PROBLEM WITH TWO SUBS IS WHEN THE PERCEIVED LEVEL AS MEASURED AT THE EAR IS 3dB OR QUIETER, DUE TO DIFFERING ROOM POSITION AND BOUDARY REINFORCEMENT. If it is over 3dB difference then the perceptual contribution of the 2nd sub is zip.
I explain that also here:
Finally, I describe a way to get good results for the Marantz AV7005 using XT's level measurements, no external SPL meter needed, and only one sub out here:Marantz AV7005
In A/V reproduction accuracy, there is no concept of "accounting for taste". We don't "pick" the level of bass any more than we get to pick the ending of a play. High fidelity is an unbiased, neutral, exact copy (or "reproduction") of the original source's tonal balance, timing, dynamics, etc..
Last edited by m. zillch; 08-05-2014 at 06:41 PM.
Are you saying that even if I have multiple subs equidistant to the MLP I should be level matching at the MLP as opposed to gain matching?? Can you elaborate on this a bit? I'm very interested in the theory behind this! Specifically, why do you say that at 3db difference there is no effect from the second (or 3rd, or 4th??) sub?
Let's say I have 3 subs, 2 up front and 1 in back close to the MLP - all 3 are gain matched. The 2 up front measure 72db at the MLP combined. The 1 in back measures 75db at the MLP. Are you saying that the 2 front subs are cancelled out by the rear because it is 3db louder at the MLP?