interesting...I run taboo with vcap & hazen mod and old zen select with hazen mod..also use zen tube buffer plus Monarchy audio dip...one classic and other 24/96...I buy them used and find that they boost sound and increase base...with decware outboard dac and Lars audio equivalent I find that my sound is smoother and less digital (harsh).  It's a pretty cheap way to improve sound.I have a smaller listening room and listen mostly to jazz so these minor tweeks fit my listening environment well.

dla405j

Thanks DBC! I wrote a question to you over in the SUPERZEN AND Z-STAGE thread. You just answered all for me. Thanks again for your insight on this. I am going to try this module. I now have a room where I can stretch the legs of my Super Zen CKC to obtain more dynamics-not-just tone and texture that I have enjoyed over the years with the SE84CS and now CKC.  My Zu Union's in Sangria Red arrive next week!   -Stone

DBC, are you running two of the mid bass and one or two subs?

My imagination is tickled, I bet you have killer sound.

Thanks for the info. I can imagine it sounds really rich and deep. I know you enjoy the sound very much, and that is what counts.

DougK,

You ask a great question. I have to say going in to this (experimentation with the MBM) my past experience and preconceived notions on what I thought I knew about subwoofers was actually an impediment. After all if you know the world is flat then you are unlikely to set sail for the horizon.

A little background. My Klipsch RF-7 mains are full range speakers. I've been to the local Klipsch dealer and when they crank them up with 200 Solid State Watts per channel they can kick out the bass. Problem is you have to play them loud and your ears start to bleed from the Solid State highs after about 5 minutes.

Come home crank the RF-7's with my Super Zen 2 Watts per channel and the mids and highs are to die for at normal listening levels. But where's all the Bass ??  I can hear it but it's a little faint for my liking.  Well lets crank it up some more and I start to drive the Super Zen into clipping.

No problem, I've got the HSU ULS-15 (15 inch sealed sub) tucked into the front right corner of my listening room. Turn that baby on and set the crossover at 90 Hz (max crossover setting on this sub). Yuck, it's boomy. Darn I've got a room induced peak at around 70 HZ. Turn the sub volume down from 50% to 20% and no more Boom, in fact pretty much no more nothing.

OK lets set the crossover at 50 Hz and the volume back to 50%. That sounds really good with Black Sabbath, Nickle Back and other music with lots of low bass (hey lets start spinning some RAPP) not really. Does not do much for The Rolling Stones though ??? OK Lets move the sub to the Front Left Corner. Darn, I've got a peak around 45 Hz there.

OK let's move the sub more to the center of the room along the front wall. Not too bad. I have the sub volume at 50% and crossover set at 90 Hz (max). I'm listening at a comfortable level, Super Zen sounds good and the music has a little meat on it's bones, I like it. Lets see if there is more of that to be had, tweak the sub volume up to 55%. What happened  ?? That does not sound natural. OK, sub volume back to 50%. I like what I'm hearing but wish I could get some more of that. Another point, now that the sub is in the center of the front wall I don't have the really low 20 Hz extension on movies ??

OK, fast forward to today. Having used the MBM (mid bass module) for months now I can appreciate how much music material lies between 50 and 150 Hz (150 Hz max crossover setting on the MBM). I don't think it was a mistake that Dr. Hsu designed and optimized to MBM to accurately reproduce material in this range. If you read some of Dr. Hsu's material he states below 50 Hz you need a big heavy driver and above 50 Hz a smaller lighter driver is optimal.

My Theory: You have a sub reproducing low frequency up to 100 Hz as an example (assuming no room induced peaks, good luck on that). As you increase the the sub volume at some point your brain says there is a disconnect between everything below 100 Hz which is going up in volume and everything above 100 Hz which is not going up in volume because the mains are producing that portion.

As you increase the volume on the MBM the frequency range that Dr Hsu felt was important (50 to 150 Hz) increases across the board as opposed to my example above using a single subwoofer and the mains.

I have to admit I was sure there would be a conflict to deal with given that my mains go down to 40 Hz. Certainly the MBM and Mains reproducing the same frequency range was going to be a problem. Well I run the MBM crossover at 150 Hz (max) and there is no issue. Basically just keep increasing the MBM volume until you brain says that's not right. Back the MBM volume off just a tad and enjoy.

Now will a system with a single MBM benefit by introducing a good sub, well yes. For reference I would say 80% of the performance bang comes from the MBM. Add a good subwoofer and you can increase performance (Weight & Body) another 20%. I think this goes right back to the fact that most music material does not have a lot going on below 50 Hz.

Recap:

Best room location for a box to reproduce frequencies below 50 Hz is often not the best location for a box to reproduce frequencies above 50 Hz.

Best driver to reproduce frequencies below 50 Hz is not the best driver choice to reproduce frequencies above 50 Hz.

Listening using a single MBM as opposed to a single Subwoofer there is a whole lot more going on in the bass region above 50 Hz then below on most music material. Therefore IMHO using a single MBM has a more profound impact on the overall "WEIGHT & BODY"  of the overall presentation.

Dr. Hsu knew something I didn't when he decided to build a box optimized to reproduce frequencies between 50 and 150 Hz.

The new Super Zen heightens the performance of the MBM compared to my 12 year old stock Zen Select. Point being if your source or amp are a tad muddy on the low end that will be reproduced by the MBM.

Final Thought: Prior to receiving the Super Zen I had a tendency to tinker with the MBM module volume. With better more modern recordings it seemed I could run the volume a tad higher without the MBM calling attention to itself. Older material could get a tad muddy so I would tweak the volume down a tad. Since introducing the Super Zen I have not touched the MBM volume. I think this is due to the Super's improved low end clarity and separation.

My apologies for the long winded response. If anyone does manage to get this far then I hope it was of some help.

4krow,

I agree with your comment regarding simplicity. Take my system for example; without the subs it is pretty basic which is always good. Source, pre, amp, mains.

The intent of my original post was to suggest that if someone has a simple system and would like to add a noticeable amount of quality "Weight & Body" to the overall presentation that a single HSU Mid Bass Module is a simple and effective option based on my experience.

I wanted to comment on placement also. The MBM is not all that sensitive to placement. With one unit you would want it somewhere along the front wall center or slightly off center depending on what your arrangement allows. Corners are not the best choice since at these frequencies you may start to sense that most of the bass is coming from one side of the sound stage.

I was reviewing Steve's paper on "Insights About Subwoofers" the other day.  https://www.decware.com/paper01.htm

"The common application of a sub woofer is far from high fidelity because of two things: The user turns up the volume to a level greater than his speakers, and turns up the crossover frequency to 90, 120, even 150 cycles. He does this because he is waiting to hear the sub work, and that is what it takes to get it to draw attention to itself. In this application, the response of the speakers are altered by overlapping them with a thick veil of bass."

I agree with with Steve's observations. If a sub is crossed over at say 80 Hz, as you increase the sub volume at some point the brain recognizes a disconnect between the volume of Sub frequencies below 80 Hz and Mains frequencies above 80 Hz.

On the other hand if one tries to overcome this problem by setting the crossover at say 150 Hz a second problem arises. Subwoofers by their very nature are designed to play Low & Loud and in my experience sound crappy when you attempt to cross them over at higher frequencies.

The HSU Mid Bass Module seems to solve both problems in my system. A unit optimized to reproduce frequencies between 50 and 150 Hz with accuracy and authority. No sense of "overlapping the main speakers with a thick veil of bass". The MBM simply adds to the music rather than drawing attention to itself.

DougK

You asked the following question earlier:

[b]"Can you expand on this?  Any idea why a smaller sub would add more weight than the larger one?"[/b]

First thing, the HSU Mid Bass Module is not a subwoofer in the traditional sense. So to judge it's effectiveness as I have described based on it's size alone would be a BIG mistake.

Traditional subwoofers are designed and optimized to go low and loud. Generally that means bigger, heavier drivers and bigger enclosures as your question suggests. The sealed ULS-15 does a wonderful job of going low with accuracy.

On the other hand the Mid Bass Module does a wonderful job of doing what it was designed to do. Reinforce the 50 to 150 Hz range with accuracy. If you read some of Dr Hsu's explanations on the MBM he selected a light weight 12" driver and designed the enclosure specifically for the MBM application.

So the traditional Subwoofer and the Mid Bass Module are really two different animals. I will try to explain it this way. If you are primarily into music and want to reinforce the 85% of the bass material that lies between 50 and 150 Hz on most recordings then I have found the MBM to be very effective. If you are only interested in reinforcing the last 15% of the bass material that is below 50 Hz on most recordings then a subwoofer would be a better choice.

Sure, I have both and and they sound great together. I realize however not everyone will have that luxury. I have listened to both and IMHO it's not even close. If I had to choose between the two it would be the MBM.

If I recall correctly, the effect described of 'volume intensity relative to level', it has been supported by the Fletcher-Munson curves from the 1950's. I'm sure it is in our genes for a reason, but I still envy other animals' hearing.
The sub that I used to own was a Velodyne UDL-15. I found that it was a great enhancement with the right speakers. The idea that a speaker cone was in constant 'check' in reference to the music signal seemed to be as good as it gets. But, as I stated, matched with the right speakers was important so that the two could be as seamless as possible. Driver distortion is unbelievably high in the lower regions of frequency, making less of a note and more of a thud as a rule.

Yes, and I agree with you also. It is a very good idea, using a less traditional sub that doesn't deal so much with unneeded frequencies. Correct bass reproduction, as hard as it can be to get right, is well worth it. Still, we have all visited those who have systems that they are so proud of because it can rattle windows....hmmmm to each his own I guess.

I think the big problem is phase coherence at the roll-off points... Some speaker manufacturers addressed this in the past: notably Beovox 'phase link' speakers...

They inserted an extra driver that lives in the suck out point between the bass and mid units... And it is phased especially to make a smoother transition...

Quote:

"Beovox," now there's a name I haven't heard in a while in a serious audiophile discussion.

Thanks again DBC for your insight with the Hsu mid bass module. It is a more efficient paper cone & driver motor too (by design as you eluded too)....to keep up with my Union Driver.

Out in the room, just a few feet away from my Listening Chair....is where I will start for placement. Anyway, after some time with my new Zu Unions and then the mid bass module I will return with some observations & pics.   Party on Wayne - party on Garth.....-Stone of Tone

Stone,

Have your new Union's arrived already ??  If not when do you expect them ??

Union's did ship today and are scheduled for 2/18 delivery!

I find that to be a really good point.  Low volume leaves out some information.    
    On another related note, if I remember correctly, harmonics go both ways. So if there are harmonics from say a cello that reach beyond it's scale, then the obverse is true. And harmonics are weaker signal than the original.

Hi Lon,

Been meaning to post but been too busy listening or working. I've actually been getting up an hour early each morning just so I can listen for a bit. The Super Zen and Mid Bass Module combination have provided an audible window into what is really happening in the lower frequencies. This has allowed me to tweak the system some and actually hear the improvements.

Last week I changed to a different equipment rack I had on hand in an attempt to improve vibration control. In the process I found that my two sets of Decware 1/2 meter interconnects I had been using were a tad tight so I went to a couple 1 meter pair of pure silver interconnects I have had for a long time.

It was interesting, when I powered back up and started listening my first impression was the low end was just a tad thinner. After listening for a while it was apparent that the low end was not thinner but more accurate with more clarity. Kick drum and Bass Guitar notes for instance seemed to have more space between them. Less tendency to bleed together.

Now to your question. Per Steve Deckert's advice I use the speaker level connections so that the MBM is reproducing as close as it can the signature of the Super Zen amp. I'm actually using common Cat-5 computer network cable purchased from Lowe's. I know, does not sound very Hi-Tek but it sounds good. The cable has four twisted pair, each individual conductor is solid copper (not stranded). I always use bare wire speaker level connections at the amp, mains, and MBM. The solid copper conductors hold up better than the very fine stranded type.

I twisted two of the pair together for the POSITIVE and the other two pair for the NEGATIVE.  So basically I have one Cat-5 cable for the left channel and one Cat-5 cable for the right channel. I have a pair of MBM's so I run them in Stereo, left channel only to left MBM, right channel only to right MBM.

I have experimented with just one MBM where I run both speaker level channels into a single MBM and the single unit performs very well in my room. The MBM has speaker level input connectors for both left and right channels. It did seem when I switched back to dual MBM's (Stereo) that low end clarity was improved a bit but it was not a night and day difference. I have implemented a few other small system tweaks since then that might account for the difference at that time ??

I did have a small ground loop issue. I run dual MBM's and ULS-15 subs in stereo mode. So left channel for instance I run speaker level connection to the left sub and daisy chain to the left MBM. Seems the MBM's would interact with the sub it was mated to. I simply ran a Radio Shack test lead with alligator clips on each end from one of the steel toggle switches on the MBM to one of the toggle switches on the ULS-15 sub to give them a common ground.

I talked to Dr. Hsu about the ground loop. Basically they expect anyone not living in a cave these days will use the line level connection. I think they expect the ground on the line level interconnect to tie all the grounds back to the amp ??

After I got my Super Zen I could just barely hear a very low level hum with the MBM's turned ON. I had to be right up next to the mains to hear this. Not audible at the listening position or with the MBM's turned OFF. I tied the the ground jumpers installed between each MBM and sub back to the case of my surge protection device where everything is plugged into. Bam, everything was dead quiet and it made a noticeable improvement in low frequency playback. Again just seemed to be a little more separation and space between instruments on the low end.

It seems if you have any type of low level distortion from your source, pre or amp the MBM is going to make that audible. In my case that has been a good thing since I have been able to identify (hear) and address these things.

The biggest advantage of the MBM is that you achieve big, full, spacious, satisfying sound at low to moderate volumes. I've been trying for 20 years to achieve this type of sound in a listening room with subwoofers and have had limited luck at best. The MBM is not a subwoofer.

I've come to appreciate that subwoofers are more of a Sledge Hammer. They are designed to reproduce frequencies that you feel more than you hear. The MBM is more of Hammer, much more nimble, more subtle.

Thanks for that info! I think if I were to use these I'd use the line level inputs from the CSP2+ . . . I will even have one of those with an extra stereo out put which would work for two or one. I like the signature of the CSP2+ so much that thanks to Bill selling one here I bought another to use with my SACD player which doesn't sound quite as good just straight into the Torii Mk III. For me the ideal preamp is a CSP2+ with three or four inputs. . . .

Anyway, your experience is really informative and I have no doubt that you are enjoying excellent sound. I'm moving to a townhome in OHio soon and will have a few neighbors; I've been living in a house with some space between neighbors for twenty plus years. I may need to listen at lower volumes, and your experience shows these HSU units can be a big benefit.

Another thought: I really like the simplicity of the HSU products. None of the "Digital Signal Processing", "Servo Control", "Parametric Equalization" or any of that other CRAP that I have tried with only limited success at best.

Who would have Thunk It, simple amp, driver and enclosure that does exactly what they say it will do.

Pale Rider,

Thanks for turning me on to Paul McGowan's daily discussions over at PS Audio. I thought this kind of fit into the topic being discussed on this thread and should be shared:

http://www.pstracks.com/pauls-posts/loudness-button/9651/

Well put DBC, like you, I have been part of this Foum for 12 years with the purchase of my Zen Select SE84CS in May of 2001. I don't post that much either and I learn things from Poster's like Lon, whom I very much appreciate on this Forum.

Now, I'm learing from you. I am ordering a MBM soon as I finish this post! Furthermore, I have a pair of Klipsch RF 52 II coming on Monday from Crutchfield. $448.98 delivered....can't complain. I have bought them for my bedroom system. However, after a long breakin...I think they will make it in for an audition in the Listening Room System.

Anyway, back to the MBM....RF 52's come Monday and the MBM by the end of next week and I'll return with some early thoughts.

I will use the MBM-12 MK2 in my Listening Room System first...and then out with the Polk 1.2 bohemoths...then with the Bedroom System....burned in RF 52 II's down the road.

I will be purchasing just one (1) MBM...I do realize you have two. I will run 14 gauge wire to them from Super Zen CKC Speaker connections to Speaker connections of MBM....placing the MBM near me/Listening Chair.




Listening Room System (12 x 14 room):

Ipad2 with Apple LossLess/CD Error correction>Cambridge Audio iD100 Docking Station >Illuminati D-60/BNC>Audio Alchemy DTI-Pro32>Prophecy Cryo-Silver Reference i2s>Audio Alchemy DDE 3.0 w/remote wand>Kimber Select 1030>Decware SuperZen CKC Amp>Kimber Select 3033> Polk LS 90....Room Acoustically treated/Dedicated Room & Adcom ACE-515 AC Enhancer // Herbie's Halo's on all Tubes & 2.5lb Mapleshade Brass weight on top of CKC Transformer // XLO Pro Power Cord to SuperZen




2 Channel Home Theater (w/Polk SDA SRS 1.2 Speakers):
(DVD, Blu-ray disc, CD, Vinyl, HDTV & Sirius Sat Radio via Dish Network)

Panasonic Blu-ray>Kimber Hero IC>Rotel RA-1062/Pre-Amp>Kimber Timbre IC>Emotiva XPA-2/(300 watts per CH into 8 ohms)>Kimber 8TC Speaker Cable>Polk SDA SRS 1.2/(use SDA always)>Kimber PK10 Palladian Power Cord to Emotiva XPA-2

Dish Network/HD DVR with Kimber KCAG IC to Rotel RA-1062/Pre-Amp.....
Sharp 46' Aquos Quattron HDTV/extra thread of Yellow (2nd only to the Pioneer Kuro)

Pro-Ject Debut Carbon (Red Plinth) to Pro-Ject Phono Box II with Audio Quest Diamondback IC to Rotel RA-1062/Pre-Amp.....

Velodyne Subwoofer wired with Kimber 8TC out of Emotiva XPA-2
Soon to be replaced by: http://www.hsuresearch.com/products/vtf-15h.html .....(fall of 2013 purchase)




Bedroom System:
Pioneer DV-563A...Illuminati D-60...Cambridge Audio DacMagic...Kimber Silver Streak...Decware SE84CS (stock)...Zen Styx w/Silver plugs...Klipsch RF 52 II

Stone, I'm pretty sure you will love those Klipsch.  I gave my brother my old (1 yr. ) pair of rb81's to help out in his system.  I loved them...great bang for the buck and Crutchfield is a great co. to buy from.

JD

....have put  concrete slabs between speakers and floorboards,
yes,...more bass firmness....and a little more subtle detail...

Thanks DBC, phasing and localization would be an issue with the MBM close to me. I will start at 150 hz as you suggested, while working on placement.

It is going to be fun using the MBM in 3 different Systems, somewhere between the mains and trying nearfield positioning and variations of... .

might be a bonus Stone, I was just getting my front firers off the floorboards, nothing to do with subs...then I thought, a few slabs on top of a sub might...  :)
The MBM sounds interesting. When you dont use subs you think you have weight and body enough. Detail of mid lows and up from a unit (not sub) well you know, it`s allways interesting to find out what lies hidden and can be brought out without comprimise. Looking forward hearing of your trials, following DBC`s good low down on them.

DBC, thanks, I do have a low level faint hum at close range and I will get some Alligator Clips from R-Shack. (Using Spkr level conn too).

I love what I'm hearing from the MBM. The unit on carpet has no issues. I have it set at 150 hz and in sealed mode just a line under half volume for my room. I have it 5 feet out from the right corner wall-along the wall far enough away from me not to cause localization.  

This is not a Subwoofer for sure! The MBM overlays so well in this hertz range. It is tuned to be articulate (fast) and subjectively dances along in tune with those upper mid bass lines. It thus, helps present an even larger soundstage with that little more weight I was craving (and at low to medium volumes)!

HSU markets the MBM for HT. The MBM needs to be sold to 2 channel music lovers with Tube Amps! Other than figuring out your placement....it does not need a long break in (you know when you hook this thing up/it has the Mojo IMHO)...even though it should benefit from that over time too.

Just a quick word on fit and finish. I ordered the Rosenut. The unit has bull nose corners like the sheet rock in my house....absolutely beautiful. The Bash Amp is recessed/routered in....very nice. The cone is a paper pulp triple surround bellow....like a Pro Eminence Driver of sorts. It exudes....I'm fast bitch!  hehe...not a Subwoofer/thick excursion.

Thanks DBC for bringing your experience with this product to the Forum.
The augmentation I'm geting with my CKC with MBM; for 625 bucks delivered is a steal. -Stone

Awesome Stone, thanks for sharing your initial impressions.

These are definitely on my radar should I need them in my upcoming new "home." Time will tell.

DBC,

Thanks for keeping us up with your Mid-bass explorations. I am enjoying it.

Will

beowulf, I can't answer that question with absolute certainty since I'm running full range mains. My guess is it might have even a greater positive impact with smaller speakers? Most Bookshelf speakers today have output down to 50-60 Hz and the MBM simply lays over or augments the 50 150 Hz range.

In my system the MBM meshes seamlessly producing a much broader more solid foundation to the music. It just adds dynamics and snap to drums and bass notes that you do not get from speakers alone. This carries throughout my house and sounds good in any of my rooms and I'm talking at only low to moderate volume.

I've been listening at lower overall volumes with much more satisfaction than ever before. The problem has always been I keep nudging the volume up looking for the BEEF and typically things get edgy before the BEEF arrives so I have to back off the volume and settle for what I can get. With the MBM the perfect amount of BEEF always seems to be there regardless of volume.

From DBC posts: Quote:


Sorry for my ignorance, but I am confused by speaker level connection. I guess your amp has only one set of binding posts out...Are you running two wires off each speaker out post?

This is fun thread. I, like many, have spent a lot of time, money and struggle with this 150 or so down frequency range. I have it sounding exceptional now, and I am beginning with more power (Torii MkIII) and my speakers (HR-1) go low easily and well....but...you know...this thread makes me wonder.

With this room, there is no place between my speakers for an MBM, so I am thinking it may not work for me...

Stone: How is your placement exploration going?

Do you guys think it may be possible for a single unit to work outside the speakers. I sort of doubt it. When I had a Veladyne sub years ago, even it, with a lower crossover, sounded better between the speakers, though it was still good much closer to one than the other.

I am wondering if it might be worth the trial thing knowing it would have to be placed outside the main speakers.

Will, the answer is yes, two sets of wires off of the amp left and right speaker posts. I use Kimber between the amp and Speakers. I use Cat-5 network cable between the amp and Mid Bass Module.

The Mid Bass Module has a very high input impedance which means it draws virtually no current from the amp so the small Cat-5 conductors work just fine. For a Single MBM I have used a single Cat-5 cable which has 4 twisted pair. I strip back the insulation and twist conductors together to effectively have two twisted pair (left plus & minus, right plus & minus). So basically you end up with one contained cable that carries the left and right signals and it is good for longer runs (especially when experimenting with multiple locations). I prefer the Cat-5 with solid conductors, they seem more durable.

As far as placement I have only tried it once outside the speakers. Placing the MBM in the front right corner in my room resulted in a 60-70 Hz room induced peak. This was a room issue unrelated to the MBM best I can tell. In a different room it may have been fine ???  So in all honesty I can't answer that question. I can say using a single MBM located next to my right speaker sounded good (it does not sound like the bass is weighted to the right side of the soundstage at all).

It's interesting and maybe Stone can share his thoughts here but with the MBM pretty much anywhere along my front wall I can never actually hear IT. All I hear is the improvement it adds to the overall music presentation, no audible directionality. It very well could be fine as long as it is not directly beside or behind your listening position.

In general I have found the MBM to be very forgiving as far as placement and integration into the rest of the system. Nowhere near the issues that regular subwoofers seem to always present.

Okay, Stone is listening to Heartfelt by Fourplay (Larry Carlton, Bob James, Nathan East & Harvey Mason).

Nathan's Bass Line on this whole Album is integrated so well without getting in the way of the Super Zen CKC's (those Jupiter Caps per your Topology=unreal Steve)....mojo Magic...... .

Period=Stone has dropped the MIC and left the building.....(back to the Listening Room).   Cheers

Oops, I forgot to thank you for your input on MBM placement and hookup clarification DBC. I do appreciate your careful and informative observations! Looks like it could be worth a try here...A bit of a crap shoot with the room mode based on placement thing you have mentioned, and since my options are very limited, but hmmmm...I have to consider it more.

Thanks for the pointers and adjustments DBC. As I spend more time with the MBM....I will get things fleshed out.

I could not resist moving the MBM to my HT Rig and placing it as suggested by HSU, behind my couch where I sit. It has been a fun weekend having it back there!

I have my RF-7 II's coming on Wednesday or Thursday. I find out from the Trucking Co. today...!  They ship on a Palet...as yours probably did too....for safe arrival/keeping.

I had to do it. I moved the Klipsch RF-7 II's to my 2.1.1 Rig (w/MBM 12 & Velo Sub). You can drive them with 2 watts/ch as DBC can attest to. However, boy do they love power! .....running off my Emotiva XPA-2. I am going to enjoy them in this Rig for awhile and then get them in to the Listening Room eventually (they are big and heavy when moving them by yourself)...along with the return of the MBM 12.

I put the RF-52 II's back in the Bedroom System to stay. They do a nice job in this BRoom Rig setup.   Cheers, Stone

Thanks for this review DBC.  I find it ironic there is so little in the way of reviews on the MBM-12.  I added a pair near-field behind the couch to compliment my pair of Hsu VTF-2 MK3 subs up front.  Amazing difference in performance, especially in music performance.  Thanks again for taking the time to write this up, its one of the few reviews for these MBMs.

Yes the Yamaha 3010 processor has dual independent low level sub outputs and thats what Im using for both the subs and MBMs.  The outputs are split and the Yammy is set for a front/rear sub configuration.  Good phase was a priority for me and luckily YPAO got my distances very accurate, especially considering Im running a pair off each output.  Crossover from satellites to low levels are higher than Ive ever preferred but after much experimenting with 80 Hz I found that 90 Hz just works better.  The VTFs take over at 45 Hz to prevent phasing and reinforcement as much as possible.  

My gain is really determined by YPAO.  Both subs and MBMs are well below 25%, like 15%,  otherwise YPAO would come back during room calibration and say the gain is too high and it cant lower them enough. Im hyper sensitive to localization and yet even near field with a 90 Hz crossover I get no localization and excellent performance.  Sounds very natural, mellow and with no boom at all, very hard to argue with what YPAO does in the gain department.  However I can see running a higher gain if they were far field along my front stage.  Luckily Ive never had any buzzing.  I listen to my system pretty loud with both music and theater so I think Im good, free of any ground loop issues, thanks for the heads up.    

shold350,

This is how I isolated and solved the problem. Get yourself some test leads with alligator clips on each end, I use these from Radio Shack:

http://www.radioshack.com/product/index.jsp?productId=2062622

They come in a 4-pack so you can clip them together to create a single longer lead as required.

Clip one end of the test lead on to any of the toggle switches on your MBM amp. Clip the other end of the test lead on to the case of the surge protector that you have all your other gear connected to. This will connect the chassis of your MBM amp to the same earth ground as everything else in your system.

If your surge protector is properly grounded, then the MBM chassis will be on the same earth ground as all your other equipment and this should eliminate the hum. Not the most elegant solution but it is very effective.

If you have the MBM power cord connected to a surge protector be sure you are using one of the "High Current Outlets" on the surge protector. The MBM needs a good bit of juice since it has a 350 watt internal amp.

You probably noticed the HSU MBM has a 2-prong power cord (no earth ground). I discussed this curious choice with Dr. Hsu. My understanding is they went this way to minimize Hum issues associated with Poor Earth Ground Wiring found in many homes. If your home wiring does not have a good ground to earth to begin with then refrigerators and other appliances can feed electrical noise back into your system through the earth ground.

Bottom line is if you want a completely Hum Free (Ground Loop Free) audio system you have to have a home that is properly wired to earth ground to begin with. Second, to eliminate any potential Ground Loop between components within your audio system each component chassis must be properly connected to the same earth ground. Connecting the ground jumper as I outline above should do that.

Let me know how you make out.

Shold350, Sorry for the confusion. I have three audio surge protection strips and all three have metal housings (cases). The metal housing is connected to earth ground per the electrical schematic provided in the owners manual.

If your surge protection strip has an all plastic outer housing clipping the MBM ground jumper wire to the plastic will not establish a path to earth ground. If your surge protection strip has threaded coax connectors for cable surge protection (see photo) clipping to the threaded outer portion will work also. In the photo the green jumper wire from MBM toggle switch is connected to the surge strip via the outer threaded portion of the coax connector.

The ground post of any unused receptacle will work also but I don't think you will be able to clip to it ??

shold350,

Glad to help. When do you expect to receive your new speakers?

Phil has basically the same gear and is getting good results (see attached link for comments).

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1361290817/15#15

Bump

shold350,

I have the Oppo BDP-83SE, DVD's & Blue Ray's typically have lower output levels than CD's (have to turn the volume knob up as you describe). No hum in my system with higher volume settings.

Is the Hum coming primarily from your main speakers, mid bass module or both? Any 60 hz hum from a ground loop would become more audible as you increase the MBM volume knob setting.

Since hum disappears when removing the Oppo interconnects it sounds like a ground loop between the Oppo and Amp. This suggests the Amp power cord and Oppo power cord are not seeing the same clean connection to earth ground when plugged in? Say for example the power cord earth ground connection on the Oppo is not as good as the power cord earth ground connection on your Amp. What happens is that any AC in the Oppo chassis (that would normally flow harmlessly to ground through the Oppo power cord) instead finds an easier path to ground through the interconnects and Amp power cord.

First thing I would do is go Oppo Direct to Amp, Amp to Mains and mid bass module turned OFF. If hum is still present disconnect speaker level connections to the mid bass module to eliminate it entirely. If hum persists try connecting a test lead from the Amp chassis to wall socket earth ground. Do the same for the Oppo if necessary.


This link might give you some more ideas: http://www.audioholics.com/home-theater-connection/ground-loops-eliminating-syst...

DBC,
Thanks for all of your help on this. I am modifying my home built stand tonight and will be putting the system back together tomorrow. It will give me a chance to try some of the tips that you have given me. The hum is not noticeable when any music is on but having to turn up the volume quite a bit on some concert dvd's it is noticeable between songs. Might be too picky? Just want to get the best out of what is truly a nice sounding setup. I have about 15 to 20 hours playing time on the system and it is starting to open up I think. I am relocating my MBM from a side location to the front. This is requiring a modification to my stand but it sounds much better in the front.
If you have some tips as to posting pics on the new user forum I would like to try some. Thanks again for the advice and by the way it was your comments on the MBM that made me buy one. It was truly the icing on the cake.

shold350,

You are not being too picky. For comparison this morning I was playing J. Joplin on my Oppo. I hit Pause and turned the volume knob on my Super Zen all the way UP. I had to have my ear very close to the main speaker drivers to hear only the faintest of hum.

I strongly recommend you get a quality surge protection device to plug all your equipment into such as this affordable unit from Tripp Lite:

http://www.amazon.com/Tripp-Lite-ISOBAR6ULTRA-Isobar-Protector/dp/B0000513US/ref...

Down the road you might want to consider an Isolation Transformer for your source components. This is basically the same unit Decware uses for their equipment demos and was recommended to me by Steve Deckert:

http://www.amazon.com/gp/product/B00006HPHN/ref=oh_details_o02_s00_i00?ie=UTF8&p...

I don't think an Isolation Transformer will solve your ground loop issue. These are used primarily to filter out noise on the incoming AC line that can induce hiss, static and hum into your source components.

If you use the Tripp Lite Isobar plug everything into that so each piece of equipment is on the same ground. The Mid Bass Module has a 2-prong plug (no earth ground) so I suggest clipping one end of a test lead to one of the MBM toggle switches and the other end to the metal case of the Isobar. This grounds the MBM amp chassis to the same ground as your other equipment.

If you do have a ground loop (60 hz hum) the MBM is very capable of making that audible. If you don't solve the Hum issue then you will only be able to set the MBM volume knob at about 30% (any higher and the bass gets boomy because of the 60 hz peak created by the ground loop). Once I solved my ground loop issue I was able to set the MBM volume at 50% with no boomy tendency. I have not touched the volume knob on my MBM for over a year now.

You are right about placement of the MBM for music. Sounds best along the front wall somewhere between the mains for best imaging when using a single MBM. Should note that once I solved my ground loop my MBM was not sensitive to placement anywhere between the mains.

s,

Yeah, I know all about having to explain and justify things to a wife. That held my system back for a long time, and when I lost her to lymphoma and MDS my system was able to grow and bloom in ways it probably never could with her around.

Still I'd rather have a boombox and VHS recorder than not have her if I had that choice! So hold your wife close and always tell her you love her!

shold350,

I was just curious as to any progress you may have made since your last post a couple weeks ago?

I was also interested in your impressions of the Oppo BDP-105 on music. I run the older BDP-83SE (Special Edition) directly into my Zen (no pre-amp). Have used the Decware CSP2 a couple of times but prefer the sound of my Oppo directly into the Zen amp.

Anyway, hope you are having fun with the new system.

Wanted to add that placing a Sub Dude II isolation platform under my Mid Bass Modules and Sub Dude HT under my Subs really made a difference. I have a wood floor and was amazed how much energy was being transferred into the floor via the MBM & Sub enclosure feet. The floor was acting like a big radiator.

Did not think it possible to improve Bass & Mid Bass further but the isolation platforms made a very noticeable improvement (better clarity, even smoother bass). For the price I highly recommend the Auralex product on any suspended floor (carpeted or not).

http://www.sweetwater.com/store/detail/SubDudeII

I'm intrigued with this deep Omega product.  I have a pair of the Omega Alinco 7xrs speakers and they are very nice...just a bit too hot with some recordings but this is easily corrected with tube rolling.  In my main system where I use HR-1s, I'm for the most part satisfied with the amount of bass I get but when it comes to rock/blues, I'm often left wanting more Bass.  The Omega might be the ticket.  I'll do some research.  So what is the frequency range of the HSU?  Mark.

PS...just looked at the site...$1500 might be more than I want to spend right now.  Where did you get the specs for the deep omega 12?  ...Duh,  it's right next to the price.  28 to 160 HZ

http://omegaloudspeakers.com/deepomega12.html

The 8 inch sub at $900 is more like it...same frequency response, lower sensitivity...

http://omegaloudspeakers.com/deepomega8.html

Thanks Doug,  the two Subs I plan on looking at are those from Omega and the least expensive one at Zu Audio (own the Souls).  I researched these in the past then put it off for some reason.  I'll keep my eyes open for used or discounts...because I'm "Penny Wise and Pound foolish".  Mark.

PS...I just checked the Zu Audio Sub..."Undertone".  It's a sealed 12 inch for 2 grand.  The frequencies covered seem a bit limited...14 to 80 Hz compared to the Omega Subs.

http://www.zuaudio.com/loudspeakers/undertone

Doug, I'm sold.  And yes, I read your posts on the HSU Mid Bass Module as you were writing them.  I just finished reading all the posts on the deep Omega on the Omega thread.  Sounds like I should save my pennies and go for the Big Boy at $1500. Mark.

maddog07,

I've read your posts with great interest and have no doubt the Augie's are everything you say they are, and would love to hear them. Problem is I don't build speakers (no time so no interest in building).

Originally I purchased a pair of Hsu ULS-15 subs (15" sealed) and of all the conventional subs I have had in my listening room these are by far the most musical. They sounded great with a crossover of 60hz but anything higher and they started to get just a tad Boomy.

So this got me interested in the Hsu Mid Bass Module which utilizes a very light 12" driver to play cleanly up into the 150hz range. Once I integrated the MBM into my system it was clear that in my system & my room reinforcing from 50 to 150hz was of much greater benefit (to my ear) than reinforcing below 50hz. If you can do both then great.

Just curious where you find the best crossover setting for the Augie's in your room, your system and to suit your personal taste?

Thanks for adding to the conversation.

Beowulf,  those Outlaws are way under priced.  By my calculus, they should have a final price at least $1000...maybe even $1500, higher after this "Introductory price" goes away. I know these would be wonderful and I'm thinking how could I work these into my listening life.  But the Zu Souls are top dog in my Den where they sit beside my Omega Alinco 7XRSs.  In this second system, where I usually don't play them very loud, I'm not even sure I'd want a pair of Subs.  The Zu Audio Souls of all three pair of my speakers, give the deepest, most satisfying Bass.  And the HR-1s will never be taken out of the listening cave.  If I ever cleaned up my living room, that's very large, I could see buying a product like this. But do I really "need" a third system?  Mark.

I had an email exchange with Canada Rob over at the Omega forum a while back which I don't think he will mind if I share here.

Quote:


My email response to Canada Rob:

Quote:


I currently have my MBM's stacked on top of my Subs in their intended Down Firing placement. I have also tried the MBM's laying on their sides in a Forward Firing configuration. To my ear I prefer Down Firing but this is simply personal taste, others may well prefer Front Firing. To my ear the Down Firing radial dispersion creates a slightly wider and deeper soundstage.

Mark58,

Read this review and especially the comments that follow regarding concrete. I work in an industrial environment and am quite familiar with how efficiently concrete transmits vibration to walls that are anchored to a concrete floor.

http://www.htguys.com/news/2010/12/5/auralex-subdude-video-review.html

I tried 24" x 24" by 1.5" thick poured concrete pavers from Lowe's one time as equipment rack shelves to eliminate shelf vibration. These things weighed 30 pounds each and vibrated a lot more than any other material I experimented with. I realize this is counter intuitive but it was the case.

Your room is relatively small which means it will be easier to Overload it, Point being you want to hear the deepOMEGA and not the room structure interacting with the deepOMEGA as described in this link.

I thought this comment in response to the product review at the link provided below describes better than I could have the positive results I experienced when I installed the Sub Dude Isolation platforms under my Subs and Mid Bass Modules.

Since installing the Sub Dude's I have dramatically reduced floor & side wall vibration. As a result my Subs are much less placement sensitive since they produce fewer unwanted interactions with the room surfaces.


Quote:



http://www.htguys.com/news/2010/12/5/auralex-subdude-video-review.html

Quote:


I have two Mid Bass Modules placed about 6" from what I call the Front Wall (the wall in front of my listening position where my mains are located). This does not create excessive wall vibrations that degrade Bass quality since the acoustic energy is being dispersed into the room radially (diffused in all directions).

The problem I had was the Down Firing MBM was driving all of it's acoustic energy directly into the floor before being radiated outward. This caused the entire floor to vibrate and that vibration was transmitted to the adjacent walls as well. In my case Installing the Sub Dude platform blocked the direct & concentrated transfer of acoustic energy from the Down Firing driver to the floor and eliminated about 90% of my floor & wall vibration. The result in my room was noticeably Cleaner and more Articulate base.

Quote:


This is what I use, it performs as advertised and looks very nice in the home (nice discrete finish).

http://www.sweetwater.com/store/detail/SubDudeII

The Gramma series are not finished as nicely and are intended more for Studios & Bands.

Mark58,

Not sure which ones you are referring to? This link looks at 6 different types:

http://ehomerecordingstudio.com/monitor-isolation-pad/

I use the Auralex Sub Dude HT under my Klipsch RF-7 main towers and 15" subs because they both have big footprints. I use the smaller size Sube Dude II under my smaller Mid Bass Modules. I've also used the Auralex MOPADS under Monitor Sized speakers with good results.

The Isoacustic Monitor stands have gotten a lot of good recommendations. The minimum height on these is 3 inches, minimum height on the MOPAD is about 1" as I recall. I used the MOPAD only because the lower profile worked better for the application I had. Both have the ability to tilt the Monitor Fore & Aft.

Mark58,

One big side benefit when I installed the Sub Dude's was that my Sub's became much less placement sensitive. Makes sense looking back. If the Sub is transmitting mechanical energy into the floor it will probably excite the floor & sidewalls differently as you locate it at different points in the room.

Isolate the sub (stop mechanical transfer of vibrations into the floor) then all you have to deal with is how the acoustic energy (sound waves) excite the room boundaries. Wish I had experimented with Sub Isolation years ago.