DIY "Balanced Force" subwoofer?

[Audiophiliac]

Ok, while I ponder on whether or not to DIY my own speakers, I think I can manage a sub easy enough. But I want to do something a bit different and unique.

I already have 2 of these subs in my car...but I got a new one to try, so I was thinking of using them for a home sub. And now I want to add a third sub and do my own version of Martin Logan's Balanced Force design. Basically a 6-sided enclosure with the drivers 120 degrees from each other. The idea is that the vibrations from the drivers cancel each other out and the cabinet is virtually inert. It works too. They do the old nickel trick where you can stand a nickel on end on the top of the Descent subwoofer and play it at normal volumes and the nickel stands.

Anyway..my question is has anyone done something similar? I scoured the archives and searched and didnt come across anything. Here are the subs...Elemental Designs EU700 6.5". Make no mistake, these things can boogie. They do well for me in the car.

http://edesignaudio.com/product.php?cid=15&pid=32&cur=USD

And for reference, here is the ML Descent:

http://www.us.martinlogan.com/speaker_details/descent.html#balancedforce

I havent done any research yet on amps, but I will either put in a 200-300 A/B plate amp, or I will go outboard and do something else. Krell FPB200M anyone? Hehe we have one traded in that I am thinking of grabbing. But I doubt it.

[ThomasW]

I'm sorry but I fail to comprehend the significance of the nickle standing up? And what that has to do with a high performance sub?

The standard design for home subs when one wants to avoid having the unit 'walk' is to mount a pair of drivers on opposite sides of the cabinet.

Generally speaking we avoid using poly coned drivers for subs, since the cones aren't very stiff, therefore their operation isn't linear (pistonic)

[Hdale85]

I think its supposed to show that the enclosure doesnt move enough to knock the nickel over? Not sure if thats an acurate test at all.

[joetama]

I understand what they are trying to say, but don't know if it's a ultra important thing.....

Also, do you REALLY want to use eD subs? You would be lots better to go with something else from the car audio world....

If you want to know a better sub let me know.....

[ThomasW]

A pair of the 12" TC2+ from www.oaudio.com would lay waste to 3-6.5" drivers

[joetama]

How about RE, Stereo Integrity, Sound Splinter, and Image Dynmics.

I would seriously look at a pair of rl-p's or rl-i's before I looked at much else from the Car Audio world if you want to go that way.

[ThomasW]

How about RE, Stereo Integrity, Sound Splinter, and Image Dynmics.

We recommend the SS RL-p15 all the time. The 12" isn't a good choice for home use.

[joetama]

I have never heard the 12" but I have heard the 15" and it's a really good sounding sub. Just out of curiosity why do you not recommend the 12"? Just not enough low-end?

[Audiophiliac]

Well I am going to use the eD 6.5s since I already have 2 of them, and its only another $50 for the third.

I didnt mean that because it wont knock a nickel over, thats the only reason its good, it was just a bullet. The Descent is one of the best subs I have heard. Period. Regardless of the nickel trick.....but it is kind of entertaining.

This is only a "project" sub. Nothing to be taken too serious. And if you havent heard what they can do, then you shouldnt say anything. For a 6.5" driver, they do some downright nuts stuff. But anyway, I am going to use them, and I am going to use 3 of them in the ML style cabinet. I was just looking for experience with this kind of design not advice on a different design altogether. Thanks though.

If I was looking for an all out performer, I would just get the Martin Logan Descent or something else. But this is DIY...something to keep me busy for a few weekends and to get me some practice for the next projects down the road.

[Hdale85]

I heard that sub and wasnt to impressed with it. Of course ive never really been impressed with commercial subs. I mean the martin logan was a nice sub dont get me wrong but it was so expensive and just didnt seem worth it to me.

[ThomasW]

Does eD have the T/S parameters posted somewhere?

[Audiophiliac]

T/S for EU700

re 3.2
fs - 28hz
bl - 13.3 TM
qms - 10.5
qts - .29
qes -.3
vas - 22 L
xmax - 13mm




What did you not like about the Descent? Its super fast, super accurate, and plays super low, and goes plenty loud enough. What else do you need in a sub?

[Hdale85]

Just didnt have that much output in my mind. And it didnt play that low i dont think. Didnt sound like it to me anyways could have just been the setup but im not sure? it was a pretty nice room setup though. Was at a place called Ultimate Electronics in Pheonix,AZ but for the money it costs to get one of those i know i could do way better with diy

[Audiophiliac]

If it was at Ultimate, good chance it wasnt set up optimally or even hooked up right. I worked there for a while, and we had a salesman that hooked up his first SACD player and ranted about how crappy SACD sounded and he hated it. Come to find out, he didnt set up the bass management so there was no bass. Idiot! Half of the stuff there wasnt set up correctly. They are out of business now.

Descent has enough output for most normal people We cranked it up on movies and it was freakin loud. Not as loud as a HGS-18 mind you, but plenty loud enough. I dont know how loud you need it to go, but I am definitely no basshead. Of course I preferred the Wilson Watch Dog, but $10k is too expensive for me.

I guess it just depends on listening habits and material. Of course any discussion on how something sounds is completely subjective.

[Jack Gilvey]

now I want to add a third sub and do my own version of Martin Logan's Balanced Force design. Basically a 6-sided enclosure with the drivers 120 degrees from each other. The idea is that the vibrations from the drivers cancel each other out and the cabinet is virtually inert.

Putting drivers on opposite sides of a sub enclosure is frequently recommended to cancel reactive forces. It's the most common installation for IB subs, where multiple drivers is the norm and the baffle is a wall of a house. So, it's a very good idea, but the 3-driver/6-sided cab won't do anything that two drivers at 180 degrees can't achieve.

From the ML site:

Although ports are a convenient and cost-effective way of increasing low-frequency output, they rely on resonant energy in a way that impairs bass quality. A good sealed system will exhibit less transient-blurring group delay...

It'd be interesting to measure the actual GD of the Descent. The requisite HP filters (sometimes pretty aggressive) seen in commercial sealed subs can push GD even higher than that seen in a 4th-order ported system.
It'd also be interesting to see a demonstrated correlation between GD and perceived "transient blurring".

[SteveCallas]

Of course I preferred the Wilson Watch Dog, but $10k is too expensive for me.

Your views and expectations would do a 180 if you built a quality DIY sub - the $10k Watch Dog can't do much below 20hz, and a ported sub designed for home use that uses 18" drivers and can't do much below 20hz is....well, flawed. It looks nice though

[---k---]

I've had a ML Decent in my house next to my twin DIY RL-p15. It wasn't a contest. The DIY subs laid waste to the Decent.

Anyway, one thing to keep in mind about your 6.5" drivers: in a car, you get A LOT of cabin gain, that really helps. In a home, you get room gain, but it is no where near what you get in a car. A home is also a much much bigger space. It takes a lot more driver displacement to get the same impact as a little driver gives in a car. That is why we prefer big 15" drivers. There is no replacement for displacement! 15" drivers are usually marginally more expensive than the 12". So, just get the 15". Only consider a 12" when size is an issue.

I'm sure you can build a sub with those 6.5" drivers. If this is just a fun project, that you don't expect a ton out of, then go for it. Have fun. I'm sure everyone here will be happy to help you. But, we don't want to see you waste your time also, and hence all the other recommendations. So, if you want seriously good performance, that will embarrass that Decent, you would be much happier with a 15" sub using a driver such as the RL-p15.

Let us know what your goals are. Make sure you look at the DIY showcase sticky, probably best to start with one of those.

[Hdale85]

If it was at Ultimate, good chance it wasnt set up optimally or even hooked up right. I worked there for a while, and we had a salesman that hooked up his first SACD player and ranted about how crappy SACD sounded and he hated it. Come to find out, he didnt set up the bass management so there was no bass. Idiot! Half of the stuff there wasnt set up correctly. They are out of business now.

Descent has enough output for most normal people We cranked it up on movies and it was freakin loud. Not as loud as a HGS-18 mind you, but plenty loud enough. I dont know how loud you need it to go, but I am definitely no basshead. Of course I preferred the Wilson Watch Dog, but $10k is too expensive for me.

I guess it just depends on listening habits and material. Of course any discussion on how something sounds is completely subjective.

The ultimate electronics i used to shop at is still up. So i dont know if maybe one you shopped at closed or what not but i just checked the website and stuff and its still there. I listend to my old Klipsch speakers there before i bought them and a Sunfire ultimate reciever and loved them both so im pretty sure they had some idea what they were doing. The martin logan sub was in a dedicated room with other martin logan speakers before they stopped carrying martin logan.

[Audiophiliac]

Man, I dont know how you guys listen to music, or what kind of music you listen to, but if readily available subs arent loud enough or play low enough for you, thats too bad.


PS...the Wilson Watch Dog isnt the big 600 lb. passive dual 18" monster (The XS). Its the "smaller" single 12" beast. http://wilsonaudio.com/products/watchdog/index.html

[SteveCallas]

Man, I dont know how you guys listen to music, or what kind of music you listen to, but if readily available subs arent loud enough or play low enough for you, thats too bad.

:roll: Too bad for the manufacturers that is :T

[Hdale85]

A lot of the commercial subs I've listend to wont even extend below like 25hz some dont even get down below 30hz. Thats just not right in my eyes :B. And besides that I know i can do way better by building my own. I had a 12" Klipsch sub in AZ and i wasnt really happy with it. It costed like 600 bucks. I'm planning on building a sub that has 2 TC2+ 12's that i know will kill it for about the same price most likely. So commercial is just not an option for a sub. Which is why you see a lot of people with high end commercial speakers but choose to build their own subs.

[ThomasW]

Man, I dont know how you guys listen to music, or what kind of music you listen to, but if readily available subs arent loud enough or play low enough for you

The DIY sub builder quickly discovers a new world where loud, low, tight, hi-def bass is a way of life, not the exception.

If true to form Dave Wilson is using a Aurasound 12" in the Watch Dog. He uses dual Aura Sound 18"s in the XS.

The DIY builder can easily reproduce the performance of the several thousand $$$ retail sub for a fraction the price. As I'm sure you're aware, the markup on speakers like those from Wilson's are roughly 900% from mfgr's cost.

[Hdale85]

Not to mention you still need good output at those low frequencys and a lot of commercial subs dont do that. Note my comment on output Its not so much how loud it is but the quality and precision, and ability to put out those low notes with enough output to be able to hear them.