Calibrating 3 Subs

[NorCalRP]

I just ordered a third sub- an Ultimax 18" Kit from PE. I have an SVS PC-2000 and a HSU VTF-3 MK4, running them with a Denon 4400H.

I'm hoping to learn the best way to dial them in. I know the level matching is going to really limit the Ultimax's, and I'm cool with that as I'm moving towards quad Ultimaxes. I'm also decently knowledgeable on determining placement on duals.

I'm looking at a MiniDSP DDRC-24, but am unsure if this is the best solution and also what the best way to hook the three of them up given I have just two sub outs. Do I hook the two existing subs into one pre-out after level matching all three of them and plugging the Crown that's going to drive the Ultimax into the second pre-out?

 

[ryanosaur]

I haven't used any of the MiniDSP gear like that yet, but that seems to be a great way to proceed. REW and programming something like the 2x4HD is all you would need, I think. I'm certain somebody with firsthand knowledge can clarify.

 

[Brettc]

I built the 18” sub from PE but me not knowing what I was doing I ordered the reference sub instead of the ultimaz I used the Dayton 1000wt amp they recommend and I can’t get up to %50 without clipping


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[NorCalRP]

I built the 18” sub from PE but me not knowing what I was doing I ordered the reference sub instead of the ultimaz I used the Dayton 1000wt amp they recommend and I can’t get up to %50 without clipping


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I ordered the Crown XLS 2502. I've been told by a decent number of folks that they're running XLS 1502's bridged, which will deliver 1550W @ 4 Ohms, without problems. I know the Crowns have peak limiters, but couldn't really tell from the PE sight if the Dayton has the same.

I chose the 2502 because I'm hoping to run each set of duals with one amp, thereby using one pre-out on my AVR per pair, with a DSP in between the AVR and the amp. I've been told the Ultimax runs closer to 6 Ohms, so those amps would deliver approximately 680 wpc at that impedence.

 

[NorCalRP]

I haven't used any of the MiniDSP gear like that yet, but that seems to be a great way to proceed. REW and programming something like the 2x4HD is all you would need, I think. I'm certain somebody with firsthand knowledge can clarify.

The DDRC-24 has Dirac Live built into it. Is that an alternative to REW? I read that the DDRC-24 doesn't have the same learning curve as REW. I'd definitely get a U-mik with it as that's what I'd use with REW as well. I've read from some folks that the miniDSP with Dirac doesn't correct AS well as using REW, but if it gets close enough, the ease if use seems really attractive.

 

[Brettc]

I’m definitely gonna order the ultimax . I’m a music mostly person. From what I can tell it’ll do much better


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[lovinthehd]

Where are the three subs going to be positioned relative to your primary seat? Are you going to run the ported subs in a sealed mode now?

 

[NorCalRP]

Where are the three subs going to be positioned relative to your primary seat? Are you going to run the ported subs in a sealed mode now?

Man that second question is a great one. I wonder if a PC-2000 can be run with the port plugged. I hadn't even considered that.

Right now my SVS is up front, inside the left tower, and the HSU is nearfield, directly behind the MLP.

 

[lovinthehd]

Your avr can dotwo different level/delay settings, so maybe one pair equidistant vs the other. Running different subs will have its own quirks one way or the other....maybe read up on Geddes' approach....

 

[NorCalRP]

Your avr can dotwo different level/delay settings, so maybe one pair equidistant vs the other. Running different subs will have its own quirks one way or the other....maybe read up on Geddes' approach....

Holy smokes! Very cool info. I'm looking forward to trying this. The idea of raising one of the subs is very cool. I've read about it before, but had never thought to even try to wrap my head around the why of it- knowing that bass is omnidirectional, I think I still had this image in my mind of a horizontal, dual axis situation, rather than having that third, vertical axis incorporated.

I think it'd be easy to raise up my PC-2000 close to the mains. I think I still want a sub nearfield, so playing around with the location of the third makes the most sense to me at this point. One thing I know with absolute certainty is that I need to purchase a good mic and a serviceable dB meter. The spectrum analysis, and the process for performing it makes so much sense to me.

I think one thing that's separates serious hobbyists from casual HT folks is the enjoyment derived from the process and not just the final result. I'm glad I have a brand new laptop to perform all this work!

 

[ryanosaur]

The DDRC-24 has Dirac Live built into it. Is that an alternative to REW? I read that the DDRC-24 doesn't have the same learning curve as REW. I'd definitely get a U-mik with it as that's what I'd use with REW as well. I've read from some folks that the miniDSP with Dirac doesn't correct AS well as using REW, but if it gets close enough, the ease if use seems really attractive.

A lot of the cats here just use REW. I am only starting to learn it myself. I've been looking at the MDSP DDRC88A with the BM module added... that is Dirac's special Bass Management. there are different ways to achieve what you are talking about... I'm hesitant to want to spend the money on that extra gear, though. The least expensive way is definitely learning REW and using the 2x4HD unit. *shrugs

Definitely agree with Lovin about familiarizing yourself with the Geddes approach. I think it is the most pragmatic insofar as he encourages strategic, asymmetrical placement where the subs will perform the best in-room, as opposed to others that recommend symmetry. As you learn a little more about acoustics, the symmetrical approach leads to greater likelihood of creating more standing waves. The Geddes approach is looking for ways to minimize that!

 

[ryanosaur]

http://seriousaudioblog.blogspot.com/2012/05/two-great-articles-on-multiple.html

 

[NorCalRP]

http://seriousaudioblog.blogspot.com/2012/05/two-great-articles-on-multiple.html

This is the article I read:

https://mehlau.net/audio/multisub_geddes/

 

[NorCalRP]

Although the 4400 can independently calibrate two subs, will it perform the same delay function as a standalone DSP unit? I'm also wondering how to hook it all up. I feel reasonably sure I'll have to use one pre-out for the Ultimax, but am not sure what to do with the others- do I get a splitter coning straight out of the pre-out. If I so that, how would I get separate measurements and the ability to independently adjust each sub?

Man, I'm in for a course in bass management, and I'm looking forward to it!

 

[ryanosaur]

This is the article I read:

https://mehlau.net/audio/multisub_geddes/

That's the one I started with! It's a good introduction to his process.

Here's a good video from one of our friends here at AH, Matthew J Poes:

Also, from Geddes himself:

 

[ryanosaur]

Although the 4400 can independently calibrate two subs, will it perform the same delay function as a standalone DSP unit? I'm also wondering how to hook it all up. I feel reasonably sure I'll have to use one pre-out for the Ultimax, but am not sure what to do with the others- do I get a splitter coning straight out of the pre-out. If I so that, how would I get separate measurements and the ability to independently adjust each sub?

Man, I'm in for a course in bass management, and I'm looking forward to it!

I think if I understand it correctly, the 2x4 (for example) takes both signal in and allows you to put 4 out... and you can adjust each output yourself through programming the DSP in REW. Just an example.
I have corresponded with MiniDSP... the guy that answered my questions was super informative and helpful. Just remember they are in Hong Kong. (take day or two to get a reply, depending on when you ask.)

 

[lovinthehd]

Although the 4400 can independently calibrate two subs, will it perform the same delay function as a standalone DSP unit? I'm also wondering how to hook it all up. I feel reasonably sure I'll have to use one pre-out for the Ultimax, but am not sure what to do with the others- do I get a splitter coning straight out of the pre-out. If I so that, how would I get separate measurements and the ability to independently adjust each sub?

Man, I'm in for a course in bass management, and I'm looking forward to it!

The XT32/SubEQ feature in your avr can handle setting the delay for two different subs. So with three subs you need to use a splitter on one sub pre-out and treat them as a single sub, so best they're the same sub and equidistant. The alternate is as mentioned something like a miniDSP 2x4 where you can adjust four different subs for delay/level/eq (using just one pre-out on the avr, then let the avr treat the subs as one for matching to your speakers).

 

[NorCalRP]

@ryanosaur & @lovinthehd I checked out the video that Gene and Hugo did on the miniDSP, and I'm sold. I had to watch bits and pieces of it, as I was at work, but as I understand it, I'll be using it with REW . I think the theory to be learned by using REW is worth the investment of time vs the ease of use with the Dirac integrated product. I could theoretically use just one sub-out to individually calibrate each sub. It looks like a super cool product.

 

[lovinthehd]

Yes, generally if using a minidsp you want to use just one sub pre-out, no point in having the avr's dual sub capability confusing things so to speak. Even when using the avr's two-sub capability it only sets level/delay per sub, then eq's them together (which is generally preferable).

 

[NorCalRP]

Not sure which one to get. There is an option on the 2x4 for 0.9Vrms or 2.0Vrms. The option on the 2x4hd is 2.0Vrms or 4.9Vrms. I read somewhere it's got something to do with attenuation (yet another of a million things I need to learn, haha!) and also that it has something to do with the subs power handling (?). Just want to get the right component.