[scorpion]

May be some are interested in my latest developments. I finally put together one prototype pair of OBs with my B200s and cheap Chinese ProAudio SW-12.
It performs way beyond expectations. Some pictures will give the setup. 19 mm MDF. Bassmodul is a topless U-baffle 65 (26") x 45 (18") cm with 22.5 cm (9") 90 degree wings. B200 panel above is 45/65 x 45 cm and screwed to two roundwood small poles which currently is also attached to the Bass module. Bass units are just screwed to the baffle from behind isolated by a thick rubber isolation.



Some may recognize the look of the speaker, this is the left one the right is a mirror image. How Oldtimer/Nigel got to his design I do not know, mine are
carefully calculated with the help of the Edge-program to assist the B200 where it dips from 200 to 800 Hz. I have experimented with this trapzoid shape
before and like it.

From behind it all look like this:



There is perhaps an innovation in that the B200 is held in place with the help of Venetian Blind ropes. It works beautiful and is a clear alternative to magnet
mount. The B200 rests on a 15 mm broad 9 mm thick rubber strip seal. Nothing is transmitted to the baffle.





The reason I built the baffles this way is a wish to be able to use different chassis on a separate baffle together with the bassunits.With testtones there are resonances with the too tight coupling with the roundwood and the bass-baffle. You can hear nothing on music but I have already som ideas how to decouple the bassbaffle from the B200-baffle. The Bass-units are the same as the wellknown Swedish audiophile Josef Svalander use in his big OBs. They are cheap but perform silent and clean well above their 22 $ price tag. Fs is 26 Hz and Qts = .98. I would estimate a usable Xmax of +- 6 mm.



The speakers are driven with these units:



Bottom right is the small Trends TA 10.1 class D amp driving the B200. Crossover between bass and B200 is 150 Hz 48 dB/octave Linkwitz-Riley slope.
The Sony CD-transport is robust and wellperforming. CDs are fed directly via SPDIF inteface into a Behringer SRC 2496 second from top. This also take analog inputs via the NAD preamp (Vinyl and Tuner). The SRC 2496 convert all to digital 24 bit 96 kHz sample rate and feed balanced signals into the top DCX2496. Here are
filters applied before signals again is converted into analogue and fed to the amps. Resulting in this frequency response:



I replaced the frequency response image (070504) with a more visible in BW, it is essentially 30 - 18000 Hz +- 5 dB in my listening room. In fact it performs like that also. Very open, good imaging, definition and depth. You can't in fact wish for more. It is real high class. 

/Erling

[ttan98]

Very nice setup, question please where do you get your Audio Pro drivers, at $22 each?

[scorpion]

In Sweden they are imported by HiFi Kit in Stockholm. I tried another basspeaker DBR12  which Swedish Car Speaker company MDS has OEMed with P Audio in Thailand. That speaker was clearly inferior to this SW-12. Much noisier and more limited Xmax.

/Erling

[Wind Chaser]

Now that's ultra innovative cool...

The second image had me fooled for a moment as the venetian cord looks a lot like your speaker cable running various errands.

Sure wish I lived in your neighborhood, love to listen to your gig.

[ttan98]

scorpion,

I goggle the brand Proaudio subwoofer, I could not find  the manufacturer who made the subwoofer you are using.

Would you give more info, eg manufacturer's name, possibly a website name?

I live in Australia..

many thanks

[Polarbear]

Very nice Erling

Looks like a fine setup. I have also used the SW12 drivers. They are very nice for the price.

How much Eq. have you applied to get the nice graph?

Cheers
Bjorn

[mcgsxr]

Very interesting, and the first time I have seen a driver tied to a baffle!  Can you share where you found the large rubber seal that you are using between b200 and baffle?

Are the wings of the bass unit mildly slanted/splayed outward?  Table saw used to create that angle I assume, and can you share why that angle?

I like the look, it is along the lines of why mine are angled like they are, but with math to back it up!

Nicely done!

[gooberdude]

Your design brings an entirely different meaning to the phrase 'Gettin' Roped In'

very cool...

[scorpion]

Wind Chaser,

You are more than welcome anytime. I'll rest for now building permanent speakers in solid birch, but I think I'll go for the
Phase Plugs also.

ttan98,

I am afraid I don't know. It is imported here and probably is the importer setting the trademark. I suppose it is just a lucky strike
they got some decent speakers, otherwise these are the kind of which there are 13 on the dozen. This firm import some speakers from Chinese
manafacturer Tonwel but I do not know if they are involved.

Björn,

You should be able to tell the difference between SW12 and the better Peerless XLS and your new 18" dynaBel speakers. My impression is
that within its limits the SW12 is surprisingly good. I'll go a step further and dampen their baskets and secure the magnets with bitumen. With two units per side
I feel no need for more bass.

With regard to filters. Not very much. There is a LP/HP crossover at 150 Hz 48 dB/octave relieving B200 of the Bass.
There is a Bandpass filter at 80 Hz Q:1.3 Gain: - 10 dB. My room is 25 x 15 x 8 feet and something is happening in the lower region, but the Bass is very clean and not boomy at all. No Bass augmentation is necessary. If I am to believe my measurements, and I am (to what I can hear and playing around with testtones), response is pretty straight down to 30 Hz.

Next I am very much mimicing the BSC/LR-circuit in that there is a shelving HP filter 6 dB slope from 600 Hz with a gain of - 6 dB followed by
another shelve HP 12 dB slope at 10 kHz with a gain of + 5 dB.

Mark,

It is a photografic illusion. 90 degrees wings nothing special. I believe MJK when he states that there will be no resonances in this design.
You can't hear any as compared to putting elements in a W-, U- or N-dipol or a Ripol when they are quite obvoius. I think I can take these woofers up to 250 Hz without any problems sonically.

As I live in a cold country I have used a standard Swedish strip seal of a kind we use to seal chinks of the doors or windows, albeit the biggest dimension I could find locally. I also experimented with twisted (swedish: tovad) wool for isolation between the B200 and the Baffel as Björn and Vidar Öierås had pointed to.
That was effective also but not better than strip seal, which is much easier to get and work with.

All,

Thanks for the appreciation. These speakers are not on the ropes, neither roped in, instead you have to know the ropes. 

/Erling

[opnly bafld]

Erling,
Nice setup with the speaker system.

All,

Thanks for the appreciation. These speakers are not on the ropes, neither roped in, instead you have to know the ropes. 

/Erling

Also, nice job with the English slang. 

Lin

[ttan98]

scorpion,

I mean you ask you about your OB twin woofer operation,

1. do you use equalization of the woofer at the bottom end, say around 30-100 hz.
   If so please elaborate.

2. In your woofer U frame configuration do you use notch filter to remove any peaks, if they exist in your setup. If so please elaborate.

3. Do you connect the woofer in parallel? If not please elaborate.

Thanks

[scorpion]

I am using a Behringer DCX 2496 for crossover and to shape response. Crossover and filters as reported earlier here except the notch at 80 Hz as answered below.

To your questions:

1. No equalization at all.

2. Yes, a roomdependent notchfilter at 80 Hz - 5dB with a bandwidth of 32 Hz, that is a Q-value of 2.5, now after I have trimmed response to full satisfaction. Speakers are 90 cms from the short wall behind and 90 cms from side wall. Room is 7.5 m x 4.5 m x 2.4 m.

3. Yes, woofers in parallell, impedance about 2.5 ohms. No problem for the NAD 216 amp driving them.

/Erling

[scorpion]

These speakers are at last to be shown at a DIY-show in Uppsala,Sweden this weekend. I have done some alterations since last. Bitumen have been applied to all woofer legs. One pair of woofers are  string hold like the B200s, one pair is screwed to the baffle. There are less vibrations from the stringhold woofers. But I really don't know if it matters. I think the Bitumen does its work OK.

The woofers are cheap Chinese ones, with overall good build quality but not really those precise responding, in fact these are very hard to judge. You know you have heard better ones. But here they sound quite OK. So let's see what spectators decide ?

I have been occupied lately with the 'Volks-OB', good as it is there is no comparison to the Visaton B200 regarding performance. The SP130X-8 of Monacor is perhaps something like 80-90 % of the B200 and extremely alikesounding in charachter. However the bass for the 'Volks-OB' is way better.

/Erling