TOPIC:

Hello, brand new user here.
I currently have an LXmini which uses the miniDSP to drive the four LXmini drivers. I am currrenty using them with an old, (but still great sounding), HSU sub which has its own external amp and crosover. I use the crossover in the subamplifier, (which is, of course analog). to drive the LXmini's mini DSP. I noticed, however, that when I switch the subwoofer in there is a change in the stereo image. For some reason the subwoofer, or its crossover, is causing the image to be pulled to the right. I think I might solve this problem by using a second miniDSP to replace the Subwoofer's analog crossover by hooking the second one up in series with the one in the LXmini. Is there any reason why this won't work? If so, which plug-in should I use? I assume the 2x4 Advanced.

Are you able to do acoustic measurements?

Hello John,
If you mean do I have the UMIK-1 the answer is no. I haven't ordered the second miniDSP yet. One of the questions I had was do I need the mike to integrate the HSU sw into the system with the miniDSP, or is it just a "nice to have"?
Currently, I have the SW located across the room from my LXminis, next to my listening position with the ampifier phase switch set to 180 degrees and the crossovver set at 62 hz. This is the way HSU recommended it be set up when I bought it many years ago. (I've used it with several different speakers over the years). This arrangement has worked well, but if I could improve things more by doing measurements, I'd give it a go. I'm assuming the "pull to the right" problem I mentioned in my original post is a recently developed defect in te SW crossoveer, since I'v never noticed it before.
paugust

Hi again I did mean acoustic measurements, whether UMIK or some other means. I would not try to integrate a sub without being able to measure it. You may be able to hear when something is wrong, but you can't tell what is wrong (and therefore how to fix it). Sermon over

I would be inclined to change your connection schema. Instead of driving the miniDSP from the HSU line level output, do it the other way around. There would be no lowpass filtering on the LXmini but you can adjust the lowpass filter on the Hsu to get the best result.

Best would be an 8-channel output version. However that will obviously cost more.

If using two miniDSP 2x4, I would connect them in parallel not in series. In either case you would have the "issue" of having to change the USB cable and remember to reload the configuration every time. It's doable but I try to avoid having to do this now.

Hi John,
First of all, I take your point on being able to measure. If I proceed with this project and order another miniDSP I will certainly include the mike.
I’m not sure if your familiar with the Linkwitz LXmini or not, but if not, you should understand that when you order the driver parts from Madisound they come with a miniDSP2x4 preconfigured with a plugin set up to match the tweeter and woofer together. It assumes that the 4 amplifiers it will drive are identical, which mine are. In other words, it’s a plug and play system once the speaker cabinets have been built and the drivers installed. Because of this, I have never connected the USB port on the miniDSP to my laptop and I have no experience using the program. (Having said that, I have looked at the manual and it doesn’t look that hard and if I buy another miniDSP I’ll have to learn it).
About the HSU Subwoofer: It’s the model HRSW12V. It’s at least 12 years old. The subwoofer amp/crossover is on a separate chassis. The crossover point can only be changed by replacing a module inside the amp and it’s limited to 41, 51, 62, 75, and 91hz. All modules are 24db/octave. The crossover can be switched out for use with systems with upstream bass management. (Mine doesn’t, but would if I used a second miniDSP for bass management. Am I not correct in this, or am I missing something?) It also has a 0-180 degree switch and a volume control. That’s the extent of its adjustment capability.
About your first suggestion: If I understand what you’re saying, this would get the SW crossover out of the LXmini circuit and may solve my “Pull to the Right” problem, but one of the big advantages of having a subwoofer is to take the strain of subsonics off the regular woofer. When I use my LXminis now without the SW they sound great if there’s not a lot of info below about 40hz. But, if there’s a lot of LF stuff the woofer cones flop around and distort unless I cut back the volume. Who wants to cut back the volume?
Second miniDSP in series: What I suggested in my first post was to simply replace the old analog crossover in the SW with another miniDSP. The new one would be in front of the current one and draw off the low frequency signal and sent it directly to the SW amp, (with its Crossover turned off). The old DSP would then receive only signals higher that the crossover frequency to pass on to the LXmini Amps. The reason I was reluctant to jump right in and do it, is that I’m not sure you can hook two up in series. Will it work? Is there a potential problem I’m missing? The only problem I can see is that it adds another ATD/DTA conversion in the path which is probably not desirable in itself. I imagine if you do enough of thee it would be audible. But, then, passive analog crossover don enhance the sound either.
I’ve attached diagrams of my present configuration and my proposed series configuration for clarity.
Thanks for the dialog. I really appreciate it.
paugust

I think you have a problem with incorrect "Y"ing in your present configuration. Your preamp outputs look back into the subwoofer outputs when you have only the LXmini selected. This is most likely your "shifting to one side" issue.
You should probably employ a 4-pole switch so you can totally isolate when in the LXmini position.

I like John's "parallel" suggestion as well. Get another identical miniDSP unit and use one for left channel and one for right channel. That would allow to get rid of your manual stereo switch as well.

That said, I don't particularily like this subwoofer scheme for the LXmini system. I believe you should use two subwoofers and they should be much more tightly integrated with the main speakers. I have an excellent example on the OPLUG forum.

Dave.

Cross Spectrum Labs have some discount umiks available.

Hi Dave.
Are you saying that I'm getting a refledton from the SW crossover circuits causing my problem? If so, I suppose I could add a second switch to eliminate that problem. It's just that I like the ideas of being able to switch the SWs in and out. Thanks for the observation, I'll work on it.

I've thought about using two DSPs in parallel but then how do I modifiy the first one? Wouldn't I loose SL's custom plug & play plugin for the LXminis? It would still have to be in play for both DSPs above the SW crossover, right? Maybe this is an easy problem to solve, but, as I've said, I have no experiance with the miniDSP program. Your thoughts?

Are you the Daveys of the OPLUG forum? If so, I've followed your dual SW solution and would love to do it, but I would have to get a new wife first. Our current HSU with its polished wood top makes a perfect end table. Replacing it with two boxes next to the LXminis would not go no matter how spectacularly they might be finished. Sometimes our hobby can be a tough one.
paugust

Your DAC output is shorted to the sub crossover output. Hard to know what exactly it will do but it is not something you would normally want to do.

Sorry too hardto edit quotes on ipad, but in terms of optimizing what you have, if you put the sub "after" the 2x4 you would turn off the peak boost on the lxmini woofer and adjust the sub xover to match. Then you can use the 2x4 to address room modes in sub region as well.

Just a suggestuon