[wendelltate]

I have been bitten by the open baffle bug. A friend of mine purchased some Spatial Hologram M1 a couple of weeks ago. I can't believe the sound from these speakers. I used to work at a hi-end store in town and have heard many very expensive highly reviewed speakers. None of them come close to these. One day last week I even took my Fisher 400 cx-2 and paired it with these. It was a slice of heaven. The sound stage, the bass, the richness and detail are incredible.

I am interested in trying something of my own. I have built econowaves so I have some experience in building. I want as much as I can get of the M1 sound but I do understand that these are $4k speakers. I have read about the Hestia, the gainphile, and the Manzanita builds. I would like to keep the size close to that. I am also on a fairly limited budget.
Which design is going to get me some/most odd that M1 sound in my smallish listening space.
Thanks in advance.

[ebag4]

Welcome to AC!
I have built a few different OB speakers (4 pair+ a number of test rigs) over the last 10 years or so, My current speakers are my favorite by a decent margin.  My room is also small (10.5'x12.5'x8') but it is dedicated so I am able to make it work.  My current OB speakers are the GR Research Wedgies with 2x12" servo subs in "H" alignment per channel.  The soundstage and presence of these speakers have really done it for me to the point I am essentially looking at other areas to make improvements and no longer feel I need to look to upgrade my speakers.  Check out the "Something that sounds incredible" thread on the GR Research circle here at AC: http://www.audiocircle.com/index.php?topic=126112.0

Best of luck!
Ed

[rabbit]

check "gainphile" blog, he has some nice cheap OBs, and contrary to thoes you mention he did it right. no coaxial with its poor dispersion, consideration into dipole peak, active EQ etc.

if you would want to go all the way linkwitz lx521 is one of the best out there. it does cost, but you could end up keeping them for decades.

[mcgsxr]

As a counterpoint, you may want to consider building up a set of cheap OB's to see how they work in your room.

I have often recommended the Visaton b200 or even a car 6x9 on some mdf as a window into how it works for you in your room.

Afterwards, you can determine just how far you want to take it.

[wendelltate]

Thanks for the replies.  I have looked at the GR Research and the gainphile builds. They look great. I am particularly interested in the latest R16.
The Spatials that I have been listening to are passive and seem to be room independent. We have moved them from a 12 x12 room to a 40x40 room and they sound great. Again, I understand that these have two 15's in them. I would be interested in going the passive route with my first build.

[lowtech]

I suggest you research the difference between OB and Dipole radiators.  You will find lots of OB designs but only a handful of true dipoles. This in of itself should tell you something. 

[Ultralight]

I too have looked at the M1 though never actually heard them.  Too $ for me though I am sure they are fine.  However, given the dealer mark up and the cost of the drivers etc - DIY could potentially achieve the similar for much less $.  How much less, I don't know.   An alternative is the GR Research Wedgie.  Wedgie are small drivers and presumably, will be faster/quicker in the transients and have a wider sounds stage from 200hz up. Not sure as I am not an expert.  But it is something I'm looking at. 

UL

I have been bitten by the open baffle bug. A friend of mine purchased some Spatial Hologram M1 a couple of weeks ago. I can't believe the sound from these speakers. I used to work at a hi-end store in town and have heard many very expensive highly reviewed speakers. None of them come close to these. One day last week I even took my Fisher 400 cx-2 and paired it with these. It was a slice of heaven. The sound stage, the bass, the richness and detail are incredible.

I am interested in trying something of my own. I have built econowaves so I have some experie
nce in building. I want as much as I can get of the M1 sound but I do understand that these are $4k speakers. I have read about the Hestia, the gainphile, and the Manzanita builds. I would like to keep the size close to that. I am also on a fairly limited budget.
Which design is going to get me some/most odd that M1 sound in my smallish listening space.
Thanks in advance.

[BrassEar]

I would experiment with 1 or 2 Alpha 15As on mdf or plywood. Add any full range OB driver you like (MarkAudio, Fostex, AudioNirvana, etc). At that point, you are near 90% of gaining all of the magic of OB. The Alphas will give you that warm sound with a large wave launch. This is what is seducing about OB. Just throw a coil on the Alpha and you might be done if the full range driver matches closely enough.

I would not get caught up in the Spatial Hologram Horn/Controlled Directivity path. I went down that path ending with 15 inch Geddes waveguides and was not very impressed. The magic is in OB, not waveguides.

The great news about OBs is that it is very easy to get near SOTA results with inexpensive drivers. This is also the reason why Maggies are so popular. It's not the planer driver, it is the lack of the box and large wave launch. This can be easily accomplished with OB cones.

I am personally using 1 Alpha 15A on OB with 1 Heil AMT. These are crossed actively with LR4 at 1.4 KHz. They are the best speakers I have ever owned and I have owned practically everything.

[steve f]

I'll second the Alpha 15. Pick a full ranger that works well and you are pretty much at a very good starting point.

I've tried the Heils. They are a love hate affair for me. Dynamics, tone, wide frequency response, very low distortion. The deal breaker for me was no vertical dispersion at my listening distance. But oh yeah I can see why people love them.

steve

[bladesmith]

I have been on the OB quest for months and months now. And the options are endless. When I finally decided on the style/brand of my tweeter, everything started moving forward much easier/faster, from there.

Others, start out looking for the best "full range" driver they can get and experimenting from there. Maybe adding a tweeter or augmenting with a woofer. Or both.

Things like Qt's and excursion are important.  Effeciency ratings, etc, etc....

There's a lot of information out there, just take your time and enjoy the journey.

Good luck

[Tyson]

I'd recommend getting a miniDSP 4x10HD and a good mic.  I use an Earthworks M23, but the little USB mic that Parts Express sells is fine too.  The miniDSP is $499 and is a great swiss army knife of functions - active crossover, high resolution DAC, room EQ, master volume and source selection. 

I'd also strongly recommend using a pair of GR Research OB Servo subs as the bass section for any speaker you are looking to make.  OB bass in general is better than box bass, but the OB Servo subs are several notches above all other OB implementations I've heard.  Sometimes better is better, this is one of those cases.


With the miniDSP and the servo subs as your anchors, you are free to experiment widely with the mids and highs.  And since the subs have their own amps, you can also experiment with lower powered, high quality amps dedicated to the mids/highs. 

Or, if you want something where someone has done all the heavy lifting, the Wedgie is probably a good choice, as is the gainphile stuff, and I'll throw in the Nao Note II - http://www.musicanddesign.com/NaO_Note_II_RS_Details.html

And there's the Lx521 also, I haven't been as impressed with the Linkwitz rooms at RMAF the past few years, but it's still better than most of what is out there - http://www.linkwitzlab.com/LX521/Description.htm

[MJK]

My latest OB pairs an Eminence Alpha 15A and a Fostex FF85WK full range driver. The baffle is 18" wide by 24" tall and is tilted back 15 degrees. Second order crossover, active or passive (I like the passive version much better), works well. Good bass from the 15A, the Fostex full range driver is very smooth all the way to 20 kHz, and best of all low cost. Great performance at an entry level price.

[bladesmith]

My latest OB pairs an Eminence Alpha 15A and a Fostex FF85WK full range driver. The baffle is 18" wide by 24" tall and is tilted back 15 degrees. Second order crossover, active or passive (I like the passive version much better), works well. Good bass from the 15A, the Fostex full range driver is very smooth all the way to 20 kHz, and best of all low cost. Great performance at an entry level price.

MJK,

Have you experimented with U or H shaped baffles ?  Or a single wing on one side ? 

Just curious, your set up sounds interesting..

(I've heard many good things about augmenting the bass with those Alpha 15A's..)

thanks

[MJK]

MJK,

Have you experimented with U or H shaped baffles ?  Or even a single wing on one side ? 

(I've heard many good things about augmenting the bass with those Alpha 15A's..)

thanks

I have done all of those things with different dipole speaker systems that I have built over the past 10 years. This pair was requested by a friend who wanted something "small" and simple. The bass is strong enough that my teenage daughter told me the floor was vibrating in her room at the other end of the house when I played Micky Hart's Temple Caves at moderate volume last week.

[rabbit]

I would not get caught up in the Spatial Hologram Horn/Controlled Directivity path. I went down that path ending with 15 inch Geddes waveguides and was not very impressed. The magic is in OB, not waveguides.

this is just false. no fullrange driver has any dipole dispersion pattern anywhere near treble frequencies, its forword directional, with very poor offaxis control, and a dipole absolutelty needs that.
doesnt come close to CD/waveguide, thats physics, OB or not.

thats the only reason why the lx521 is a 4way speaker, to match directivity.
then you would also get much higher distortion, annoying breakup modes etc, even tiny fullrange drivers got thoes.

[JohnR]

I'm going to say "What Tyson said" but elaborate a bit.

My first "OB" was a RadioShack driver in a piece of plywood. This was about year 2000 time frame. It sounded truly awful. In retrospect, and with better knowledge now of how things really work, it was completely idiotic. But, people on certain forums were raving about it at the time.

The thing is, there is no magic. You can't pretend that the limitations of OB systems are not there. You just have to evaluate how to best make the trade-offs. I see three basic approaches:

1. Buy a commercial speaker. Clayton Shaw (Spatial?) comes to mind. There are others. In that case, there will be all the same considerations as with any commercial speaker purchase.

2. Build a documented design. There are a number, some have been mentioned already in this thread. If you do build a documented design, stick to it, build it, (ideally) measure it, and then see where you want to go next.

3. Roll your own. Warning: STEEP learning curve ahead! This is where you would be well advised to not listen to people on forums. It's a level harder than boxed speakers. I think, FWIW, etc.

Good luck

[MJK]

It's a level harder than boxed speakers. I think, FWIW, etc.

I disagree. You have to design a crossover (passive or active), just like a boxed speaker, but you do not need to design a box. That is a great simplification and eliminates a lot of risk.

If you pick the right woofer, that is compatible with an OB system (fs ~ 40 Hz and Qts ~ 1.0), and match it with a good full range or mid tweeter combination there is software available to accurately simulate the complete system. A simple passive crossover can work with the right drivers. It all hinges on the selection of the drivers, in particular the woofer(s).

You can make it as hard or as easy as you want. If you have math/physics/engineering skills it can be really easy and inexpensive (< $500) to come up with a great sounding OB speaker. If you have no math/physics/engineering skills then it is probably better to look for a commercial or established DIY design.

Don't overthink it or go for something complex for the first introduction to OB speakers. Anything that looks really complex probably has a number of pitfalls.

[rabbit]

Siegfried Linkwitz wouldnt spent 10 years and go thru hundreds of pages of documentation if this was an easy task to get right.
an OB must be atleast 3-way, and must have an active crossover to work properly. or else you will run into polarresponse issues, dipole peak issues etc. while the on-axis response often is quite random.

there are LOTS of poorly designed OB speakers out there, many of them look like lego`s with no real design goal in sight, they are just OB for the sake of it.
sure, you can audition a simple passive 2-way and say it sounds good. but that doesnt mean its a good design on paper.
a box speaker is easier to good measurable results from imo, but it will still sound somewhat like a box, because of its omni transition 

[mcgsxr]

I maintain that you don't need to go multi-way or spend a ton of money to play around with this and potentially even be happy.

You can, and if you want to you should.

Linkwitz has done a ton of research, and shared that too, no doubt.

Others here have spent tons of time finding out how this works, and why, and thankfully also share their experiences.

Sure there is science to it, but I don't personally think that you have to dive in headfirst to a driver bakeoff with measurements, and multiway amplification to "hear it".

If the complex solution is satisfying for you, awesome.  if now, don't be put off.  If this is a hobby for you, it is fine to start simple and play around.

I ended up with a full ranger on a wide winged baffle, augmented with biamped OB bass.  It was excellent.  It was 100% shared ideas in the "Gravity well of a darkstar" thread that formed my opinions about what is possible and pleasing on a budget.

I respect that there are tons of ways to find satisfaction in audio, and OB is DIY paradise.

[MJK]

Siegfried Linkwitz wouldnt spent 10 years and go thru hundreds of pages of documentation if this was an easy task to get right.
an OB must be atleast 3-way, and must have an active crossover to work properly. or else you will run into polarresponse issues, dipole peak issues etc. while the on-axis response often is quite random.

there are LOTS of poorly designed OB speakers out there, many of them look like lego`s with no real design goal in sight, they are just OB for the sake of it.
sure, you can audition a simple passive 2-way and say it sounds good. but that doesnt mean its a good design on paper.
a box speaker is easier to good measurable results from imo, but it will still sound somewhat like a box, because of its omni transition 

Spoken like a true believer.

Linkwitz has built a business based on his approach, of course he supports his methods to the fullest.

If you think about what he has done with rather crude yet elegant math models you will also see that there are other options that can work just as well. He has not make a dipole speaker in the strictest sense of the definition even though that is often claimed as the differentiator in his method. If he had discovered the holy grail of loudspeakers we would all be listening to his design. He has a lot of happy and vocal supporters, but he also has critics.

No one solution is best.