2 Subs (Rhythmik L12) Response Worse Than 1 (Hsu VTF-2 Mk5)

[CoolHandDuke]

In order to make the wife happy, I just bought 2 Rhythmik L12s to replace a larger Hsu VTF-2 Mk5. I placed the 2 subs in the areas that measured best with the Hsu (one in front between mains the other directly to left side of room). I'm getting a nasty hole below 100hz that isn't there with the single Hsu.

Do different subs have greatly different responses in the same locations? I was very disappointed to not see a more even response. I attached my Audyssey post calibration measurements for 1 vs 2 subs.

I appreciate any help because I really want to make this setup work. Did not expect to see a drop in performance with 2. I ran the calibration twice with same results.

 

[ryanosaur]

Most obvious is that you went from a ported sub to sealed... which will never have the same output down low. While the acoustics of the room have not changed, you may want to try the Sub Crawl to confirm that you have the best performing spots in the room.
If you happen to have access to REW and a measurement mic, you will get better data using that system. The "Before" graph from Audyssey can be useful, but the resolution is preety low and it can only do so much.

How large is your room?
Is it open to other areas? Closed?

 

[diskreet]

Things like the difference in driver height could possibly be causing the response to be different in the room. I'd suggest you continue playing with different locations first. Then you can look into things like phase alignment and delay (test and check, not magic answer here to find what works best in your room). Then hopefully EQ can smooth out the rest.

 

[CoolHandDuke]

@ryanosaur

I did expect the sub 30hz to change, but the hole is between 60-80hz. It's a relatively large room open to other spaces (probably just under 3000ft3). My understanding was the 2 L12s would be fairly comparable to 1 VTF2. I do have a UMIK and REW but assumed the ideal positions wouldn't change. The locations they are in were the best measured with the Hsu using REW.

 

[CoolHandDuke]

Things like the difference in driver height could possibly be causing the response to be different in the room. I'd suggest you continue playing with different locations first. Then you can look into things like phase alignment and delay (test and check, not magic answer here to find what works best in your room). Then hopefully EQ can smooth out the rest.

Thank you. Shouldn't XT32 take care of the phase and time delay for me? I figured the ideal locations would remain fairly static regardless of the sub. Guess I'll be doing a lot of measurements tomorrow.

 

[diskreet]

I have two L12's as well (I eventually added an F18 to get real low end power) but the link in my sig has more info on the results I was able to achieve with them. Let me know if there's other help we can provide.

To answer your question on XT32 I'm not sure how good a job it does with phase but it does delay for sure. I ended up adding a miniDSP when I got the third sub and I made a huge different with phase and delay on that. When I just had the two L12s I did try playing with phase on one sub at a time but never got much of a change - the dial only gives so fine of an adjustment and I wasn't great at experimenting with it.

All that said REW and a good calibrated mic were a huge help in getting real before and after measurements -the 'after' in the audyssey app is calculated so it's essentially made up. you might be getting a better end result and not even know it.

 

[CoolHandDuke]

I have two L12's as well (I eventually added an F18 to get real low end power) but the link in my sig has more info on the results I was able to achieve with them. Let me know if there's other help we can provide.

To answer your question on XT32 I'm not sure how good a job it does with phase but it does delay for sure. I ended up adding a miniDSP when I got the third sub and I made a huge different with phase and delay on that. When I just had the two L12s I did try playing with phase on one sub at a time but never got much of a change - the dial only gives so fine of an adjustment and I wasn't great at experimenting with it.

All that said REW and a good calibrated mic were a huge help in getting real before and after measurements -the 'after' in the audyssey app is calculated so it's essentially made up. you might be getting a better end result and not even know it.

I'll take measurements tomorrow to find the 2 best locations, then run my calibration, then run after-calibration measurements. Just a bit shocked to not get a better response right off the bat.

 

[ryanosaur]

The Phase control on the back of the subs will come in most handy once you get them dialed in as best as possible. If your Lady will help, use her to steer the Phase knob of the lesser Sub while you listen. When you get the strongest response, leave it and re-measure. The first Sub would likely be performing at its strongest with the Phase set to 0.

 

[ryanosaur]

I'll take measurements tomorrow to find the 2 best locations, then run my calibration, then run after-calibration measurements. Just a bit shocked to not get a better response right off the bat.

They are completely different Subs. Not saying one is any better than the other, necessarily, but just the change from ported to sealed can be significant, even switching to duals.
Keep in mind that the VTF2 is one of the best values in Subwoofage.

 

[lovinthehd]

I think this all says you should just have gotten another VTF-2

 

[CoolHandDuke]

I think this all says you should just have gotten another VTF-2

I know. The wife wanted smaller. If I can't get response to work I'll return them and she'll live with the Hsu.

 

[CoolHandDuke]

They are completely different Subs. Not saying one is any better than the other, necessarily, but just the change from ported to sealed can be significant, even switching to duals.
Keep in mind that the VTF2 is one of the best values in Subwoofage.

No doubt. I love the Hsu. Wife hoped smaller duals (in the white finish) would look nicer. They do, but it's not worth tradeoff if I can't get response to work.

 

[Pogre]

This is why we always recommend going with ported subs.

 

[lovinthehd]

Was just looking at pics of the two subs. Did you try raising the L12s up to somewhat mimic the HSU ?

 

[CoolHandDuke]

This is why we always recommend going with ported subs.

I honestly had no idea that would be the case and I've read a lot on here. I knew SPL could be an issue, but not frequency response (other than the low low end).

 

[CoolHandDuke]

I did

Was just looking at pics of the two subs. Did you try raising the L12s up to somewhat mimic the HSU ?

I did not. To tell you the truth, that would sort of defeat the purpose of the smaller form factor in my wife's eye. But maybe you are on to something with the height. I'm just hoping the ideal locations are different than with the Hsu and I can find an even balance.

 

[lovinthehd]

Yeah figured that would be low WAF, altho building some risers wouldn't be too hard. I'm just curious if that small difference is affecting your response, altho I suspect it isn't it but in your shoes I'd probably try it out for a measurement at least. Other than moving the seating around, that is....

 

[Pogre]

I honestly had no idea that would be the case and I've read a lot on here. I knew SPL could be an issue, but not frequency response (other than the low low end).

You went dual too, which was smart.

And yeah, I mean, I wouldn't have predicted a big dip like that either. Sealed subs do interact with a room differently tho, so I don't know what I would have expected. Messing around with placement might help a lot and having 2 gives you an even better chance. They may be cancelling each other out somehow too so playing with phase might help.

REW and a mic is really, really useful if you wanna get serious and dial it in. Really lets you see what's going on and a sweep only takes a couple of seconds. Audyssey is more cumbersome and I'm not really sure how accurate it is. A few of us have gotten some really good results with a MiniDSP 2x4 HD also, but with the Audyssey app out now you can achieve pretty much the same results.

 

[CoolHandDuke]

You went dual too, which was smart.

And yeah, I mean, I wouldn't have predicted a big dip like that either. Sealed subs do interact with a room differently tho, so I don't know what I would have expected. Messing around with placement might help a lot and having 2 gives you an even better chance. They may be cancelling each other out somehow too so playing with phase might help.

REW and a mic is really, really useful if you wanna get serious and dial it in. Really let's you see what's going on and a sweep only takes a couple of seconds. Audyssey is more cumbersome and I'm not really sure how accurate it is. A few of us have gotten some really good results with a MiniDSP 2x4 HD also, but with the Audyssey app out now you can achieve pretty much the same results.

I have UMIK and REW. I will take measurements tonight or tomorrow. As far as phase, should I just set 1 to zero, and then gradually change the other and take measurements at each point along the way?

 

[snakeeyes]

Well I have both. The L12 is my bedroom sub.

I have dual VTF2mk5 in my living room. There is no comparison vs L12 sealed. It’s sealed so it can’t compete with ported.

The VTF2mk5 also is noticeably more mid bass than my LVX12 in my small theater room. If WAF ever strikes in the living room, I would happily have the dual VTF2 mk5 in my theater room.