[dm]

Anyone have experience with using a HSU MBM-12 (mid base module 50-150hz) with Magnepan speakers?

I am well aware that Magnepan has a DWM for a similar mid base purpose.  However I am concerned that using a DWM in parallel with a magnepan speaker will present a 2 ohm load, something the HSU MBM does not have to worry about with it's built in plate amp.

[josh358]

What amp/Maggie are you using? Some amps seem to be comfortable with the 2 ohm load of the paralleled speakers, though I understand your concern.

Also, the HSU is more expensive, so for not much more you could put a Class D amp on the DWM to take the place of the HSU's plate amp.

Anyway, I'm not knocking the HSU -- this is the first I've heard of it but the company has a good rep. Still with a planar, the DWM will be seamless, and you'll likely get mutual coupling that enhances the output of *both* speakers. It's a dipole, so has a similar radiation pattern, and the sound of the driver is similar to that of the sound of the Maggie's woofers, while a cone sounds different. It's a challenge to match a dynamic sub seamlessly with a planar and in the midbass, it's likely to be even harder. The dipole will also excite fewer room modes for cleaner bass.

OTOH, if you're suffering from a room boundary problem. the HSU could potentially help since dipole + omni = cardiod -- in other words, the backwave from both will tend to cancel, reducing suckouts in the midbass. Also, I gather that HSU recommends running it close to the listener -- an interesting approach with which I haven't had any experience. So all bets may be off. as to which combo would sound better. (Interestingly, if a sub is right by the listening position, the response aberrations due to room acoustics are minimum phase and so can be equalized out -- I plan to try this with my own sub at some point).

[dm]

I have my Magnepan 1.6's biamp'ed with a PLLXO with a pair of Parasound HCA-1000a.  However, Parasound says, "Sustained 2 Ohm loads are not advisable with any Parasound amplifier."  I also have dual HSU TN1220 subwoofers.  Which give out significant bass.  The whole midbass thing might be over kill for me anyway.

The price of the HSU MBM-12 is $499 plus $50 shipping.
The price of the Magnepan DWM is $795 (plus the cost of an amplifier potentially)

Your points about blending planar and omni sound pattern is exactly what I was worried about with matching the HSU with a Magnepan.

[josh358]

I have my Magnepan 1.6's biamp'ed with a PLLXO with a pair of Parasound HCA-1000a.  However, Parasound says, "Sustained 2 Ohm loads are not advisable with any Parasound amplifier."  I also have dual HSU TN1220 subwoofers.  Which give out significant bass.  The whole midbass thing might be over kill for me anyway.

The price of the HSU MBM-12 is $499 plus $50 shipping.
The price of the Magnepan DWM is $795 (plus the cost of an amplifier potentially)

Your points about blending planar and omni sound pattern is exactly what I was worried about with matching the HSU with a Magnepan.

OK, sorry about that, I had checked the HSU's price but apparently saw the price for a pair.

I don't know what to say about the load. If you use an attenuating resistor on the DWM's the total impedance will be somewhat higher, but I don't know if you'll need one.

As to overkill, I think midbass is actually more important than deep bass and it's a problem area for all speakers because of cancellation effects, but particularly for dipoles since you can't "split the difference" between path lengths as you can with omnis.

But what if the DWM ended up extending the bass enough so that you didn't need your subs anymore? This is going to be room and program and listener dependent so no way to predict but with acoustic coupling the DWM/main combo can potentially give you satisfying bass down into the 20's, perhaps obviating the need for existing subs. And there's no way conventional subs are going to sound as good with planars. So you could sell your existing subs to pay for a second amp, which you could use to run the DWM's or (assuming it's happy driving 2 ohms) to biamp with a PLLXO. Biamping would also let you add a DSPeaker on the bass.

I think I'd experiment -- get the DWM on the trial, see what it does in your room -- and go from there.

[SwamisCat]

I have two DWM's and a Rhythmik sub. For speakers I have a pair of newer 3.7i's in one room and a much older pair of IIIa's in a separate room (empty nester who never sold off his old gear).

Please allow me to support Josh's comments.

The DWMs give more weight and power to the critical mid and upper bass (and even a bit in lower midrange). They make drums, bass and male vocals more realistic in size and weight, noticeably so in some cases. They are in no way a sub. Indeed in four different rooms and untold numbers of setups I have never noticed any appreciable benefit to the lowest extension (you can get a tiny bit more lower octave extension by running the DWMS exactly parallel to the main speakers, but this actually creates phase issues in many cases unless you have extremely large toe in). 

The effects of adding one (you can wire both left and right channels to one for double the bass) or two is about two to four DB increase in bass between 63 and 300 hz. The exact gain depends upon placement and which resistors you use. Careful placement can actually allow you to fill valleys by an even larger amount and even smooth out peaks.  It is like having a sub for mid and upper bass. Net result is smoother and more powerful bass instruments of all types.

Negative effects are they can overwhelm smaller rooms giving a boomy, bloated sound especially if you use two without sufficient resistors. They also counteract the super tight sound you can get from an upper bass dip, which is a pleasing effect to many.  Another negative is they are really, really hard to get perfect. They offer two more panels which need moving to get perfect sound, and any movement of mains or bass panels affects how the two react.  In general DWMs are great for those who like their panels further out from the FW. (Mine are currently out eight feet in both rooms).

They do take a good amp which can handle a two ohm load.

I prefer the sound of both sets of three series Maggies with the two DWM's. Indeed, I kinda wish I had four of the panels. They simply make the three series bigger, bolder and more powerful sounding. That said, I also love my sub, especially for the larger room. Indeed, the benefit of DWMs AND a sub is it allows me to keep the sub crossover real low and thus unobtrusive. 

Just sharing.....

[josh358]

Great post, there's nothing like practical experience! Which is why I think it's a good idea to take advantage of the trial offer, since the effect is going to be room dependent.

Not that I'm not curious about those Hsu's . . .

[sfdoddsy]

If the effect of the DWM is to add a few more dB to the midbass, why not just add an EQ such as a MiniDSP and boost with it.

Unless you are playing very loud, the effect should be the same.

[SteveFord]

Swamiscat,
How did you find they worked out with the 3.7s?
I'm a midrange freak and always want just a little bit more...

[SwamisCat]

Dodsy,

I have no experience with equalizers, so cannot comment on the actual observed tradeoffs at non peak volumes.  I guess the argument is similar to whether to get one sub with equalization, or two subs. The benefits of two are that you can not just get more volume but smoother frequency response, less strain, and you can fill true dips  which cannot be increased with equalization.

I am sure there are pros and cons to both approaches.

[SwamisCat]

Steve,

To answer, allow me to offer what I think is a major difference between the IIIa's and the 3.7i's. The older model has larger bass panels and puts out substantially lower bass in my rooms. The newer models emphasize the upper and mid bass more at the expense of the lowest octaves. Tradeoffs. If I was trying to sell speakers I would probably make the same choice as Magnepan.

Thus the older models benefit more from the DWMs than the new ones. In smaller rooms with the speakers three or four feet from the FW, the 3.7s don't really need DWM help. I prefer mine much further out, and this tends to reduce mid and especially upper bass. In larger rooms, the DWMs really help make a bigger speaker capable of more output. According to Magnepan, there is more bass area on the three series combined with DWMs than there is on a twenty series. 

Again, it is possible to overload a room. I almost always use large resistors and long runs of tiny gauge speaker wire with the bass panels to tame them down.

[sfdoddsy]

Dodsy,

I have no experience with equalizers, so cannot comment on the actual observed tradeoffs at non peak volumes.  I guess the argument is similar to whether to get one sub with equalization, or two subs. The benefits of two are that you can not just get more volume but smoother frequency response, less strain, and you can fill true dips  which cannot be increased with equalization.

I am sure there are pros and cons to both approaches.

I'm sure there are. I wasn't specifically thinking of EQing the room response with a MiniDSP or whatever, but of adding a  filter to boost the bass where it is perceived, or measured, to be weak.

At $100 for a MiniDSP versus $1400 for a pair of DWMs it's certainly worth a try.

[SteveFord]

Thanks for the reply - I know all about overloading a room.
I think I'll stick with the 2 subwoofer plan.

[dm]

thanks all for the good discussion.  One thing that keeps me from making a decision is the question of the 2 ohm load that a DWM presents to the poweramp when used in parallel with the main speakers.  Magnepan says on the web site that high current amps should be ok.  But as I mentioned earlier, in my case Parasound does not recommend sustained 2 ohm loads.

I use a PLLXO in my setup so using a Y on the analog inputs of my power amp to divide off the bass to a second power amp for the DWM would alter my input/output impedance and require a altered PLLXO design.  So I would prefer a speaker level connection to a power amp driving the DWM or just using the DWM in parallel with the main speakers and hitting the 2 ohm load.

does anyone have experience with the DWM and power amps failing to support the 2 ohm load?

[josh358]

I'm sure there are. I wasn't specifically thinking of EQing the room response with a MiniDSP or whatever, but of adding a  filter to boost the bass where it is perceived, or measured, to be weak.

At $100 for a MiniDSP versus $1400 for a pair of DWMs it's certainly worth a try.

I'm a big believer in bass EQ, because bass is so rough that it inevitably improves it. Even bass trapping doesn't eliminate the need for EQ, although it should always be used rather than EQ to the extent that that's an option. But not everyone wants to go that way. Some people are all analog and, well, you usually can't convince the others! And of course whenever you boost the bass you're reducing headroom and increasing distortion. Personally, I prefer the opposite approach -- a bigger speaker equalized down, which is what I'll do with my IVA's, which are in a room much too small for them (though not by choice).

I think some people may have been turned off by primitive equalizers that did more harm than good. Boxes like the MiniDSP or DSPeaker are a different matter entirely.

[sfdoddsy]

Agreed. My MC1s are lacking even the bass Magnepan specifies (ie down to 80Hz). They roll off from 300Hz or so.

So I've done a high shelf filter with a MiniDSP which brings the mids and treble down to the level of the bass that is there.

This actually doesn't require any more power since it is the bass the sucks all the juice, but it makes them sound almost balanced enough to be used.

[Austin08]

I was shopping for a pair of subs to go with my 3.7i, few months ago. My speaker seat along the long wall (room size is 15x 24x8) and about 2.5 feet out with about 15° toe in and about 9ft from LP. The bass is very solid and enough for most of my listening material. I did not feel I need anymore bass but do sometime miss the thump thump of heavy bass line. So I was looking at a few subs with good reputation when paring with MG like Rel T9, MG-WDM and Rythmik F8. As a current Rythmik Dual f15 owner and after many thinking, I went ahead with my gut and ordered a pair of Rythmik F8. It has been a few months since I got them and I would never look back. The F8 has the ability to allow me to play with various freq up to 250hz without ever sound boomy at any freqs. (at least in my room). I end up cross them at 100hz. They mate nicely with my 3.7i and give me the thump thump that I looking for in certain listening material.

[SwamisCat]

Austin,  is it safe to assume you were using the dual f15s in another system? Did you ever move one f15 in as a trial?

[SwamisCat]

While driving the DWMs I have only used two Different Emotiva amps and an 80 watt Sonic Frontiers tube amp. Imo the SF was not capable of even driving the Maggies by themselves. I found it all but useless, but that is just me.

The Emotiva amps -- one rated at 400 W into 4 and the other at 1000 into 4 -- sail through the load without a sweat. I am hard pressed to even get them warm to the touch.  That said, if I ask Emotiva they say NOT to run 2 ohm loads. BTW, there is zero difference to my ears between the two Emotiva amps despite large differences in power and price.

If I was a betting man I would say that Parasound amps would handle it easily. In talking to the folks  at Magnepan and reading the Maggie literature I get the sense it is an easy two ohm load especially with resistors added. I cannot speak to the issue though as I am a complete electronics idiot.

[dm]

SwamisCat,

thanks for your response.  Just to clarify your 2ohm amp comments, you are running the DWM's off of your main speakers in parallel?  No dedicated extra power amp for the DWM?

[Austin08]

Austin,  is it safe to assume you were using the dual f15s in another system? Did you ever move one f15 in as a trial?

SwamisCat,

I had dual FV15HP before then I sold them to another AC member when moved to my new house. Not long after that, I bough a used pair of F15 for my new HT. I did not try the F15 with MG due to the fact that my wife would never allow that beast in our living room so why border, I though. OTOH, I was very impressed with Rythmik sound quality from bigger brother subs and the fact that the F8 can cross at very high freg, those facts would be enough to make me believe the F8 would fit my need.