MINIDSP after Audyssey (not the usual question, though).

[robbnj]

Got a new MINI 2x4 (no-HD) and am tinkering and learning. 'Problem is I get very limited time to tinker so I do a lot of things "on paper" until I can actually spend a few minutes playing.

I ran Audyssey, then did a bunch of sweeps with REW, then made an EQ curve to clean up some sloppy spots. When I uploaded it to the DSP and ran more sweeps, it had made things worse. I already feel like getting a smooth bass response is going to be an endless game of cat-and-mouse between Audyssey and the MINIDSP, so I'm thinking of this:
1. Disconnect subs and run Audyssey, forcing my main speakers to "small", crossed over at ~100Hz.
2. Disconnect mains, re-connect subs and get them all time/phase/etc. aligned and properly EQ'd with REW and the MINIDSP, Audyssey disabled.
3. Reconnect mains, do some final minor tweaking to avoid crossover point issues.

I'd love to tell Audyssey "Only correct above 100Hz" so I can then just do the subs with MINIDSP, but I'm thinking with the speakers set to small, this is what it will do anyway.
That way, the bass is untouched so that the signal going to the MINIDSP is "virgin" even with Audyssey engaged, and I don't end up with issues form overlapping EQ curves.

Anyone tried anything like this? I'm not in a place to buy a new receiver or a suite of MINIDSPs and amps to do all my channels, so I'm trying to work with what I have. Again, I'm trying to do as much experimenting and planning on paper because of the limited play time I get.

 

[KurantAK]

If your receiver works with the MultiEQ app you can use the MultiEQ Frequency Range option to tell Audyessy not to touch any frequency you want below I believe up to 250hz for a sub.

 

[robbnj]

If your receiver works with the MultiEQ app you can use the MultiEQ Frequency Range option to tell Audyessy not to touch any frequency you want below I believe up to 250hz for a sub.

Unfortunately, my receiver is XT32 but not app-enabled. Thank you, though!

 

[lovinthehd]

The "usual" approach would be to run minidsp for subs alone then use Audyssey to incorporate with the rest of your setup.

 

[robbnj]

The "usual" approach would be to run minidsp for subs alone then use Audyssey to incorporate with the rest of your setup.

One of those contentious subjects as I've seen both ways described as "correct". My primary issue here is that I'm really unimpressed with what Audyssey does for bass management (which is supposed to be it's strong suit) in my system. I know it's not a miracle cure, but when it didn't even catch that my subs were almost fully out of phase with each other due to an errant bump of the phase control on one, I was nonplussed.

My goal is to avoid going through every possible iteration to figure out what will work, AND to avoid equalizing an already-equalized signal.

 

[lovinthehd]

One of those contentious subjects as I've seen both ways described as "correct". My primary issue here is that I'm really unimpressed with what Audyssey does for bass management (which is supposed to be it's strong suit) in my system. I know it's not a miracle cure, but when it didn't even catch that my subs were almost fully out of phase with each other due to an errant bump of the phase control on one, I was nonplussed.

My goal is to avoid going through every possible iteration to figure out what will work, AND to avoid equalizing an already-equalized signal.

e
The theory with doing minidsp to get subs as dialed in as possible is that it gives less to Audyssey to do in the way of eq, particularly if you're limiting to schroeder with the app....

ps Subs don't particularly need to be in phase with each other....

 

[robbnj]

e
The theory with doing minidsp to get subs as dialed in as possible is that it gives less to Audyssey to do in the way of eq, particularly if you're limiting to schroeder with the app....

ps Subs don't particularly need to be in phase with each other....

Therein lies the rub: Depending on who you listen to, either Audessy should be run and then MINIDSP used to tweak the results, or MINIDSP should be used to set up the subs, then Audyssey has less to deal with when doing its handiwork.
Hard to argue with anyone who has been able to get good results their way.

Can you explain more about subs not needing to be in phase? I've watched and read more than enough to confuse me, but isn't proper phase critical to avoid cancellation and major delay corrections?

 

[TLS Guy]

Therein lies the rub: Depending on who you listen to, either Audessy should be run and then MINIDSP used to tweak the results, or MINIDSP should be used to set up the subs, then Audyssey has less to deal with when doing its handiwork.
Hard to argue with anyone who has been able to get good results their way.

Can you explain more about subs not needing to be in phase? I've watched and read more than enough to confuse me, but isn't proper phase critical to avoid cancellation and major delay corrections?

It all depends on the position of the subs. If the subs are in the same plane, then they absolutely should be in phase. However if one sub is half a wave length ahead of the other, then the subs will cancel and therefore should be out of phase. However that is just for one frequency. So as you add frequencies you can never really phase them. Now you can use position to help cancel nulls and reduce peaks, but it really only works at one frequency. That is why I have trouble with the approach of scattering subs around the room. I absolutely favor an integrated system keeping everything as close to a perfectly integrated wave form and not separating fundamental frequencies from harmonics, in time and therefore phase. I know this is a minority view at present, but I firmly to believe it to be correct.

 

[robbnj]

It all depends on the position of the subs. If the subs are in the same plane, then they absolutely should be in phase. However if one sub is half a wave length ahead of the other, then the subs will cancel and therefore should be out of phase. However that is just for one frequency. So as you add frequencies you can never really phase them. Now you can use position to help cancel nulls and reduce peaks, but it really only works at one frequency. That is why I have trouble with the approach of scattering subs around the room. I absolutely favor an integrated system keeping everything as close to a perfectly integrated wave form and not separating fundamental frequencies from harmonics, in time and therefore phase. I know this is a minority view at present, but I firmly to believe it to be correct.

OK. We were talking differently about the same thing. I meant "in phase" relative to the general listening area, esp the MLP. I understand there will always be over/underlap of waves that will cause peaks and troughs in the response in a room when subs are placed any distance apart (and probably even if stacked on each other).

My two subs are at the front of my room, ALMOST symmetrically placed with respect to my mains (and not in the corners), but I am committing the ultimate sin of using two different subs of two different designs. One is a 12" true isobaric, the other is a 10" with two 10" passive radiators. At least they are both "sealed", and I have been able to get a fairly smooth combined response with REW and some MINIDSP work.

I guess I'll have to wait a few weeks and try Audyssey again with the MINIDSP already in the chain.

 

[TLS Guy]

OK. We were talking differently about the same thing. I meant "in phase" relative to the general listening area, esp the MLP. I understand there will always be over/underlap of waves that will cause peaks and troughs in the response in a room when subs are placed any distance apart (and probably even if stacked on each other).

My two subs are at the front of my room, ALMOST symmetrically placed with respect to my mains (and not in the corners), but I am committing the ultimate sin of using two different subs of two different designs. One is a 12" true isobaric, the other is a 10" with two 10" passive radiators. At least they are both "sealed", and I have been able to get a fairly smooth combined response with REW and some MINIDSP work.

I guess I'll have to wait a few weeks and try Audyssey again with the MINIDSP already in the chain.

Using different subs is in itself causing a phasing issue. You will have differing phase and group delay issues between those subs. So it is anyone's guess what the phase alignment if those subs is. Audyssey is good for setting levels and distance. It is also quite good for detecting phase, however it can not do the impossible. If the phase shift is 90 or 270 degrees then it obviously can't make a decision, and will go either way. So I suspect that your subs are more likely than not 90 or 270 degrees out of phase, or in that neighborhood, even if your phase settings on the sub say they are in phase. The phase knob can only set the electrical phase and not the overall phase response of cone and ports. This is the reason that using different subs, especially of different design like yours is not recommended, as you have a high chance of an acoustic soup.

 

[robbnj]

Using different subs is in itself causing a phasing issue. You will have differing phase and group delay issues between those subs. So it is anyone's guess what the phase alignment if those subs is. Audyssey is good for setting levels and distance. It is also quite good for detecting phase, however it can not do the impossible. If the phase shift is 90 or 270 degrees then it obviously can't make a decision, and will go either way. So I suspect that your subs are more likely than not 90 or 270 degrees out of phase, or in that neighborhood, even if your phase settings on the sub say they are in phase. The phase knob can only set the electrical phase and not the overall phase response of cone and ports. This is the reason that using different subs, especially of different design like yours is not recommended, as you have a high chance of an acoustic soup.

One of the subs has a continuously variable phase pot that offers "35-180" degrees phase adjustment. I ran many REW sweeps with both subs separate, then together, running that pot through the range, until I was able to get a pretty decent response curve out of them.

A major part of this hobby to me is learning by doing, and experimentation. I've fallen down the rabbit hole with REW and the MINIDSP, and will be down here a while.

 

[TLS Guy]

One of the subs has a continuously variable phase pot that offers "35-180" degrees phase adjustment. I ran many REW sweeps with both subs separate, then together, running that pot through the range, until I was able to get a pretty decent response curve out of them.

A major part of this hobby to me is learning by doing, and experimentation. I've fallen down the rabbit hole with REW and the MINIDSP, and will be down here a while.

If the subs were sealed your plan would work fine, as group delay in sealed subs is low. With ported subs your solution is only partial, due to phase differences between speakers and ports, and they will not be the same for different subs. So for ported different subs, there is not a total solution to the problem.

 

[lovinthehd]

FWIW a sub with passive radiators is a ported thing rather than sealed....and I definitely prefer using identical subs in multi sub setups but depends....

 

[robbnj]

FWIW a sub with passive radiators is a ported thing rather than sealed....and I definitely prefer using identical subs in multi sub setups but depends....

That's the goal, but it means two subs. The isobaric one is ancient, but a helluva performer. Would love to find another, but not a ton produced or sold. Getting rid of two and buying two new is not in the cards.