yet another B200 OB (with pics)

Rafal · « **on:** 29 Dec 2006, 06:05 pm »

Hi Folks,

So I finished my baffles and installed the B200 drivers. They are driven by Charlize and without any filters, the Charlize is certainly powerful enough. After playing them for 2 days, I find that I can bearly hear anything below 80hz, therefore I will be adding a sub. The bafles I built look nice, but are HUGE! 4ft tall and 3ft wide. Definately not acceptable. What would you say is the smallest baffle I can get away with? I was thinking about something like 25" wide and 30" tall with a driver centered around 20" from the ground and tilted back 8deg? I know it will produce less bass but I want to get at least 100hz so I can still integrate the sub.

Lastly, how long did you find the brake in period to take?

Cheers,

Rafal

JohninCR · « **Reply #1 on:** 29 Dec 2006, 07:46 pm »

It looks like alot of love went into those. I'm sorry they're not working for you.
Small is my specialty. Here are a few examples. All need the top end EQ'd down
IMO, but that's a matter of taste and the amp you use.

B200 solo in an OB-RLH, great output down to the 50's

Below is the ultimate way to go small with the B200's. It does need another driver
to supplement the bass, but it should be about equivalent to an 18" wide flat baffle.
Measurements to come, so don't copy it yet. This is a test baffle.

Here's a B200 on a 17" wide baffle with a 15" driver to augment the bass:

Of the 3 I will probably end up going with the ringed version after I do some more
experimenting and build a pair, as long as I don't find some resonance surprises when
I measure them. That shape provides a much more precise single driver sound (even with
a bass helper), than the larger baffles have. In direct listening comparisons I can clearly
hear the wave launch from the entire baffle using larger baffles, vs the center of the driver
as the sound source for the rings test baffle. The difference is not subtle and it should
pay real dividends in terms of imaging and presence. The question remains regarding
resonance and whether the shape truly negates the problems that a flat circular baffle
would present in terms of response ripples. First impressions were pretty darn good.

Rafal · « **Reply #2 on:** 30 Dec 2006, 01:57 am »

Thanks John,

The baffles I made were supposed to be "no compromize" baffles without any regard for the domestic acceptability. In retrospect, that wasn't such a good idea. They do, however, seem to be working out better and better. I am listening to them and they can play very loud without being fatiguing (and that's without using any filters). When I turn off the sub and listen to test tones, I can hear 40Hz and 50Hz does not seem too bad, so that's an improvement. I do, however, preffer augmenting the low freq. with a sub. I picked up a really nice, sealed MJ Acoustics Reference 150 and it sounds very very musical. It seems to be keeping up with the rest of the music very well.
I am very intrigued by your experiments with a "ring" baffle. I want to do something to improve imaging. When I made OB for FR125S drivers, they imaged much better. There was a very nice ambience to it. The baffles were quiet a bit smaller though (approx. 33"H, 22"W 8deg tilt). I am thinking of doing something simmilar for the B200. (36"h, 21"w, 10deg tilt, no wings, driver centre 26" from the bottom). However, maybe the ticket is the ring baffle. We'll see. Right now, I am just braking the drivers in for another week or 2.

JohninCR · « **Reply #3 on:** 30 Dec 2006, 05:07 am »

The Flintstone alignment may work great for the B200. I just haven't made an adapter to attach it, since the B200 is larger than the Eminence I originally used I can't just drop in right in. That type of folding takes some tinkering to get right, but the size benefit is worth the effort.

Rafal · « **Reply #4 on:** 30 Dec 2006, 05:09 am »

John,

What do you mean by Flintstone alignment?

JohninCR · « **Reply #5 on:** 30 Dec 2006, 05:21 am »

Sorry, I thought I included the pic.

oldtimer · « **Reply #6 on:** 30 Dec 2006, 08:13 am »

Rafal, when you say "no comprimise" what do you mean. I see several comprimises with your baffle. After 12 baffles with this driver I can say that it preforms amazingly when properly done. aa

Happy listening

markC · « **Reply #7 on:** 30 Dec 2006, 05:22 pm »

http://www.digitalaudiophiles.com/tas/nov-26-06/index.htm

You can see a few shots of my OB's above, along with the baffle step circuit, (in the little walnut box). They are 30" wide and 40" tall. The driver is 23" to centre off the floor.
I find the bsc makes a big difference in overall output with much better bass. I can now turn my sub freq. and volume down considerably. The bsc does noticably drop the efficiency of the driver.
I've also added a zobel on the driver which seems to help with the upper midrange/lower treble beaming.
Next up-Dare I say-a tweeter. I've been playing around with a cheap pair of tweeters crossed above 10k with a notch filter on the b200 to kill that nasty rise @ around 14k.
So far, it sounds encouraging, so I'm going to buy a pair of Visaton tweets to add to the mix with a proper x-over instead of throw together parts that I had on hand.
I'll use a 3rd order on the tweet and just the bsc, notch filter and zobel on the b200-no low pass.
My goal is to retain the midrange of the b200 and add some sparkle to the top end. We'll see what happens.

Rafal · « **Reply #8 on:** 30 Dec 2006, 06:23 pm »

Quote from: oldtimer on 30 Dec 2006, 08:13 am

Rafal, when you say "no comprimise" what do you mean. I see several comprimises with your baffle. After 12 baffles with this driver I can say that it preforms amazingly when properly done. aa

Happy listening

Oldtimer,

When I said "no compromize" I meant no concesions for domestic acceptance. These baffles are a bit larger than normally acceptable and are curving slightly to help minimize edge diffraction. Anyway, any design is a collection of compromizes.

Would you mind sharing details of your most successful baffle design?

Thanks,

Rafal

Folsom · « **Reply #9 on:** 5 Jan 2007, 09:09 am »

Brake them in but maybe consider Phase Plugs from Planet 10. I hear nothing but good things!

Also I should mention as people have done with B20s.... A tweeter on the backside perhaps? It is funny but if they have any angle at all they work, it is interesting, and somehow still has imaging. Yeah I am calling out the Taboo.

Rafal · « **Reply #10 on:** 9 Jan 2007, 11:51 pm »

Here are the pics of my latest iteration. They are not coated yet and will also recieve a layer of felt for the back. The dimensions are 37'"x24",3/4" thick Baltic Birch ply. the fromt is cherry veneer with walnut and oak stripes. As I'm sure its of no surprise to you, they image much better than my larger baffles. The Bas is not as good, but I just adjusted HX on the sub to 60Hz and it sounds fine. Pretty even from 40 to 130Hz save for a slight peak at 80Hz (judgind with my ears, not measurements). Overall, they sound pretty amazing and are asy to live with. I may tweak the integration with a sub and the final placement, but I'm 93% there. I'm not even using any notch filter (even though I have the parts ready and waiting).
I welcome your comments.
BTW, the design is asymetric. It's not just an optical illusion,

Cheers,

Rafal

opnly bafld · « **Reply #11 on:** 9 Jan 2007, 11:58 pm »

Very nice Rafal!

I wonder if the brace being so large and in the middle has any effect on the sound?

Lin

markC · « **Reply #12 on:** 10 Jan 2007, 12:39 am »

Looks like that rear brace could turn into a magnet mount....one of the apparent must haves; if only The Old Timer would divulge.
Rafal,
ever consider an area rug on your wood floor? Could help smooth things out a little.

Rafal · « **Reply #13 on:** 10 Jan 2007, 01:30 am »

Thanks guys,

I positioned the back brace so it's in the centre of the driver and therfore, should be the least obstructive. I did intend to use it as a brace agains the magnet but not a magnet clamp. I'm not sure what magnet clamp would add.
Regarding the rug idea, yes I thought about it. It would brobably be easiest hifi upgrade to sell my wife on

. I thought about getting a nice cow hide, but my 2 year old daughter may have some questions a bit difficult to answer. My room is pretty reflective. it consists of plaster walls, leather upholtery, hardwood, tile and a large, single pane window.

Dmason · « **Reply #14 on:** 10 Jan 2007, 01:42 am »

Very nice Rafal; Simple and effective. I am interested to know that the sealed sub integrated to your satisfaction...

If you built the cabinet of drawers as well, I would like to know where you got the late 50's style "Sputnik" chrome legs for it.

Rafal · « **Reply #15 on:** 10 Jan 2007, 02:02 am »

Quote from: Dmason on 10 Jan 2007, 01:42 am

Very nice Rafal; Simple and effective. I am interested to know that the sealed sub integrated to your satisfaction...

If you built the cabinet of drawers as well, I would like to know where you got the late 50's style "Sputnik" chrome legs for it.

Dmason,
The sub (MJ Acoustics Refference 150) seems to be keeping up pretty well. It sounds a lot more responsive and musical than my 10" Tannoy ported sub). I have started integration by playing the test tones with the sub off. At about 50-60Hz I was getting bass from the baffles albeit a light one. that's why I decided on the low pass frequency in that area. With the sub ON, the level was adjusted so the level was fairly even from 40 to 150ish HZ. When I had the sub in the corner, I heard a much louder response at 80 Hz and a lull at 90-100Hz. When I moed it out, things evened out quiet a bit. now, I'm just tweaking the level of the sub.

I did build the cabinet and bought the "Sputnik" legs at Lee Valley http://www.leevalley.com/hardware/page.aspx?c=1&p=46308&cat=3,40993,41284&ap=1

They have all kinds of cool stuff.

scorpion · « **Reply #16 on:** 10 Jan 2007, 09:43 am »

Indeed nice, Rafal, but I can see on your web that you are a true artist (and I) like Diana Krall too.

Regarding magnet mount it is supposed to add silence by removing panel resonances caused by the chassis mount.
Oldtimer's mount can be seen on this link: http://www.decware.com/cgi-bin/yabb/YaBB.cgi?board=diy;action=display;num=1143087829;start=465 and JohninCR has shown his here in your thread. I think this is a worthwhile inclusion and your brace does give ideas.

/Erling

mcgsxr · « **Reply #17 on:** 10 Jan 2007, 01:07 pm »

Lovely woodwork Rafal, are you up in London, ON?

I should shoot up the 403 some weekend, and bring my old Magnavox amp for a try in your room with those OB - that little 50+ year old amp does wonders with my fugly MDF OB b200's...

Rafal · « **Reply #18 on:** 10 Jan 2007, 02:56 pm »

Quote from: scorpion on 10 Jan 2007, 09:43 am

Indeed nice, Rafal, but I can see on your web that you are a true artist (and I) like Diana Krall too.

/Erling

Thanks Scorpion. I don't know if I would call myself a "true artist" but I hope to get there.

Quote from: mcgsxr on 10 Jan 2007, 01:07 pm

Lovely woodwork Rafal, are you up in London, ON?

I should shoot up the 403 some weekend, and bring my old Magnavox amp for a try in your room with those OB - that little 50+ year old amp does wonders with my fugly MDF OB b200's...

mcgsxr,
Getting together at some point would be awesome. We can do a little amp comparo. I am currently using a Charlize t-amp and I'm building an LM 3875 gainclone based on Peter Daniel's kit. Since I live in London On, it won't be that far and I'll make you a proper espresso or cappuchino

Cheers,

Rafal

cr_otmopo3ok · « **Reply #19 on:** 27 Mar 2007, 05:32 am »

Quote from: JohninCR on 29 Dec 2006, 07:46 pm

Of the 3 I will probably end up going with the ringed version...

Dear John,
I'm highly interested in knowing whatever results you obtained by using the ringed 'baffle' on B200.
The idea of something like this have been circling in my mind but when i saw your design it all came together finally.

I'm making a magnet mount and would like to try such a baffle too, except i think I'll mount it to the standing post also as opposed to the driver.
But before i embark on wasting numerous sheets of plywood for perfect circles I'd like to know if it's worth it.
I'll be augmenting it with some 15" driver in the future.
Thank you very much,
I find your experimentations the most inspiring.