[EProvenzano]

Hi folks,

It's been an awfully long time since I've spent any serious time here on AC...
I definitely missed the community and all the great things I was able to learn about audio.

I'm still enjoying my Ellis 1801's and Ronin Nomads immensely...but I have an itch that still needs scratching  .

Before I left I was fully engaged by the Dark Star thread and compelled to try the B200 driver.  I did acquire the drivers, but life's priorities took away most of my free time, and I never did make use of the B200.

I'm eager to get down to the business of playing beautiful music from the B200's!

I've drafted a concept drawing below, derived from little bits of knowledge I've gleaned from the various threads here, and of course mixed that with a good amount of WAF - lets face it most wives don't want monolithic speakers in their living rooms! 

I'm looking for the community here to "punch holes" in my design - so to speak.
The design is a quasi flat baffle / H-frame.

What compromises could I expect from this baffle design???

The upper driver cut out is for the B200 while the two lower cut outs are for the, yet to be determined, 12" bass drivers.  Both illustrations are similar except the image on the right has relatively larger "wings".
The dimensions are not finalized and be no means are they derived from scientific analysis.  These two options were drafted merely for me to judge the aesthetics.



TIA,
EP

[Mr Content]

Hi EP, I look forward to you enjoying your journey into OB's. Having done considerable work with the B200 in OB, there are some things you can do to refine the output. This will depend to an extent what drivers you choose for bass duties, and what xover you will employ. Your overall design is sound though, and you could confidently move forward with a baffle like this, once you have finalized the drivers etc.

Mr C aa

[gainphile2]

Hi, just a question, why pursue B200's when the cost for these expensive driver can easily buy really nice midbass + tweeters, let's say Seas L18 and T27TDFC?.

[Bemopti123]

Hi, just a question, why pursue B200's when the cost for these expensive driver can easily buy really nice midbass + tweeters, let's say Seas L18 and T27TDFC?.

He already has these drivers and needs to use them. 

[mcgsxr]

Welcome back!

The design looks good, though for me aesthetically, there is little reason to extend the base plate beyond the front of the baffle - I would retain it behind the baffle, to ensure a safe platform for the speaker to sit on, but would not have it extend all the way forward as in your design specs.

The b200 is a good driver, and there are lots of ways to make it better - phase plugs, damping the frame, amp synergy...

[Telstar]

Hi, just a question, why pursue B200's when the cost for these expensive driver can easily buy really nice midbass + tweeters, let's say Seas L18 and T27TDFC?.

The B200 aren't expensive at all: they cost 150€.

[Telstar]

About frame and wings size, the wings (average point) should be narrower than the baffle width. Wider and you risk to get the resonance under  XO point.
At eye, I would go with the first drawing.

[EProvenzano]

Hi, just a question, why pursue B200's when the cost for these expensive driver can easily buy really nice midbass + tweeters, let's say Seas L18 and T27TDFC?.

I find this is always the case in audio...you buy something today and tomorrow there is something better  .

I have not invested the time in constructing the baffles, so now would be an ideal time for me to reconsider the B200.  HOWEVER, I know zilch about xo design and don't have the time to learn even the basics.  So implementing a tweeter and mid-bass is beyond me - at least for the foreseeable future.

I am confident I can low pass the woofers using a plate amp - I know I know this is pretty basic stuff.  What can I say we all have to start somewhere .
I'm also confident that with a little trial and error I could high pass the B200 to releive it of low bass duties - again pretty basic stuff 
I do believe I will continue with the B200's as my first OB project.

Thanks for the suggestions thus far gents! 
Cheers 
EP

[EProvenzano]

Welcome back!

The design looks good, though for me aesthetically, there is little reason to extend the base plate beyond the front of the baffle - I would retain it behind the baffle, to ensure a safe platform for the speaker to sit on, but would not have it extend all the way forward as in your design specs.

The b200 is a good driver, and there are lots of ways to make it better - phase plugs, damping the frame, amp synergy...

Thanks for the welcome Mark!  Nice to see some familiar people still here.

You're right about the base.  Actually, I think you're being a bit easy on me.  That base is down right fugly  .
I threw the drawings together rather quickly.  I do plan on making some tasteful adjustments to the base and the top of the baffle.

[EProvenzano]

About frame and wings size, the wings (average point) should be narrower than the baffle width. Wider and you risk to get the resonance under  XO point.
At eye, I would go with the first drawing.

Excellent!  Thank you for this technical advise.

[EProvenzano]

What is the consensus regarding baffle thickness and edge treatment/finishing?

At first I considered simply building the baffle from 3/4 mdf.  More recently I see a trend for massive, rigid, baffles.  Also, I've seen rounded edges on several designs.  I could easily laminate 2 layers of 3/4 MDF and round the edges above the wings with a 3/4 round over.  What do you all think of this?

Thanks!

[-Richard-]

Hi EProvenzano ~

Yes... we all have to start somewhere... and beginning with your previously purchased B200's is a perfect place to start.

When we begin our creative projects (audio or otherwise) it is best to develop an immunity to being enticed to the frenetic "this is better" kind of emotional appeal... self-interest is always at the root of it... once you are into your creative design process and your listening becomes altra-sensitive... you will find out for yourself quickly enough what works and what does not.

My baffles were actually built by a master cabinet maker/designer here in Ojai... based on my initial design. We did a great deal of listening together to determine which design variations seemed to work the best. Jim is also a professional musician and recording engineer (on his own musical projects) so I had the good fortune of having another highly sensitive pair of ears to corroborate what I thought I was hearing.

What I discovered was that the longer the wings we used behind the baffles (Jim devised an exercise that allowed us to quickly change and fasten different sized wings to the edge of my simple flat baffles so we could retain an auditory "image" of what we just heard for comparison), the more distorted the musical image became... the wings seemed to introduce a "reflective" effect that smudged or smeared the musical image.

Also your design, which incorporates a frontal "wing", will probably act as a wave guide... it could "direct" the musical signal into a tight forward pattern, very much like box speakers do... and also reflect the signal back and forth between the wings and the front of the baffle... that could easily smudge the original signal with multiple delays and destroy the large radiating pattern that helps to make the Open Baffle approach sound so dimensional and fully saturated.

Here is my suggestion from a design point of view: design a baffle that allows you to temporarily attach your wings to your baffle... so you can easily take them on and off and listen critically to the music both ways... it would even be better to design your experiment so that the front wings can be taken off by themselves. Then you will learn a great deal about how your design actually affects the musical image.

In your DIY Open Baffle exploration you don't want to be lazy... I am saying this affectionately not critically... if you allow yourself a bit of time and can be patient and systematic you will learn more from this experiment than from a life time of listening to commercial speakers in an audio store or parading an endless amount of commercial speakers through your listening space. Here is where the real learning begins and it will change your listening life forever... just as it did for me and Deborah.

Not too long ago I stopped by a local dealer here in southern California to listen to the entire line of Harbeth's... a speaker I have always liked... just to see if I still felt the same way about them. Deborah and I sat listening to one model after another... Deborah, is not an audiophile by any definition that would make sense... yet she was able to discreetly point out the problems that each speaker exhibited with amazing accuracy... that is what comes from listening sensitively to a well-executed Open Baffle system for almost 4 years. You just get very good at actually being able to identify what you are hearing.

Best of luck, EProvenzano... please keep us informed of your progress and what you learn.

Warmest Regards ~ Richard

[EProvenzano]

Hi EP, I look forward to you enjoying your journey into OB's. Having done considerable work with the B200 in OB, there are some things you can do to refine the output. This will depend to an extent what drivers you choose for bass duties, and what xover you will employ. Your overall design is sound though, and you could confidently move forward with a baffle like this, once you have finalized the drivers etc.

Mr C aa

finalizing drivers...yes...this is turning out to be more difficult than I first thought.
I did some reading on the GR research web site recently on Danny's new 16ohm OB woofers. They look like the ticket, but OMG pricey for me to have brought up to Canada.

Checked out the 15" Augies too.  Same situation there.

Can anyone recommend a nice driver that might be available in Canada??

Thanks guys!

[DanH]

You can get 4 of these "Goldwood GW-212/4 12" OEM Woofer 4 Ohm" for 89.4 from Parts-Express.com. I am thinking of a similar project myself. Their fs is 38hz and qts is 1.17.

[JohnR]

I think he's saying that shipping and duties is a lot - ?

EP, CSS (in BC) has a range of sub drivers - http://www.creativesound.ca/

I don't know anything about the drivers, but you could take a look.

[PDR]

EProvenzano......I know what your getting at with the shipping costs.
When I brought my GR OBs up I couldnt believe the cost to Alberta....

But after hearing them I would do it all over again......even with the exchange rate
Those OB servo subs are phenomenal

Perry   

[EProvenzano]

It appears that several posts have disappeared from this thread.
Can a moderator recover them?

[mcgsxr]

Mine is one of the lost ones - lost during the downtime I assume.

I am not aware of any way to retreive them, not sure if the other mods might know how?

[Rudolf]

Mine is one of the lost ones - lost during the downtime I assume.
I am not aware of any way to retreive them, not sure if the other mods might know how?

Mark,
I initiated a new topic "Ode to Helsinki" just before the forum crash. It appears to have vanished too. Should I wait patiently for it to revive? Or should I start it again under the old name?

[EProvenzano]

No worries for me.  I was most interested in the several links that you all provided.  I believe I was able to recall most of them....

Would someone mind commenting on the suitability of this woofer paired with my B200's?
http://www.usspeaker.com/definimax4015lf-1.htm

I understand that the Qts is relatively low at 0.5, but not as low as many I've seen that tend to hover between 0.25 and 0.35.  Being that I'll be using EQ on the woofer from 120hz and down, can I expect decent performance?

The sensitivity, power handling, and xmax seem terrific. I assuming I'll be able to eq the low end response without reaching any of the woofers limitations (mechanical or other).

I've read that lowish inductance is favorable for an OB woofer.  Is 1.495mH considered low?

Thanks again folks!