My latest

[Andrewbee]

Visaton B200 with Rythmik Audio Servo sub (finally)

[edjosh23]

They look good

So how do they sound?

Are you using an active xo? Where are they crossed? Whats powering the B200s?
Is the sub sealed? Why is there a space next to the subwoofer cabinet , when looking at the back, to right of the amplifier there seems to be a spacer?

How are you going to finish them?

Josh

[Andrewbee]

24db built in to 350W plate amp.
B200 will be run from Charlize class "T" with a -3db filter ~ 70 hz.
Sealed sub, space because I wanted a specific footprint for the enclosure / baffle, there is a spacer which also acts to help support the sub enclosure. Finish (yeah right) will be a natural varnish. I have not played the subs yet, I just tried to put everything together this weekend, its been maybe 2 months just to get this far.

I'm off again on an ironbird tomorrow so will have to wait for next weekend to actually hear them with the subs. The B200's on their own are nice

Andrew

[Andrewbee]

Honey I'm home!

I played with the ob's for a few hours yesterday. The subs are nice
The B200's need work. The speakers are too close to the (live) rear wall and there is too much sound being reflected. I plan on putting some fibreglass or polyester batting
across the rear of the speaker to kill some of the rear sound output.
The problem is to move them around 5 -6 feet away from the rear wall would mean moving them for every listening session and they are not exactly lightweight, I may end up putting some castors on them.
I also need to build the filter for the B200's to start their rolloff at ~ 70 hz.
So, for now they show promise but I miss my Jerico's with the 208 Sigmas', even
without the newfound tuneful bass, and what a bass it is!

Andrew

[morbo]

Nice looking system! There is something very nice about the sound of a wide/fullrange + sub. I am running the rythmik right now with WR125s and after tweaking the balance with sine sweeps through the XO region, the sound is very nice and extremely dynamic. BTW, I encorage you to try moving the crossover up... I have been able to get up to about 120hz, and the servosubs sound very clean crossed that high, plus removing the bass from thee fullrange drivers really helps them, much more than your typical two way.

[Andrewbee]

Hi Morbo,
Thanks for that, I never considered crossing over that high, I suppose with stereo subs I can probably get away with it. Maybe I will try crossing up higher, the filter I had in mind was of course to do just what you say, free the fullrange driver and let it work it's magic unimpeded by bass. There is in the servo sub amp a highpass @ 100hz, I think it passes through an opamp, not sure, but why not, its worth a try.


Andrew

[ScottG]

Andrew.. for curiosities sake would you do me a favor (assuming you have the materials on hand and some spare time)?

Try the B200 aimed up at the sealing in a very lossy "large" box pulled relativly close to you, (closer than normal.. say 6 feet away) and with the driver effectivly around 70 degrees off-axis from you (..still visible, but just barely).

In otherwords in "omni" fashion, not unlike the speaker here:

http://www.6moons.com/audioreviews/fj/om.html

..though in a larger box and without the tweeter.

I think you could get the "flavor" of this configuration with something as simple as a cardboard box, (perhaps dampened with a pinned-up blanket around all the side panels - including the hole), with a very large round or square hole in the backside panel.

Now I realize that treble response will suffer (significantly even), but I think its likely, (..or I wouldn't have suggested it), that you will discover something special that you might find addictive, and that could "pave the way" to a design far more to your likeing.

[Nuuk]

In otherwords in "omni" fashion, not unlike the speaker here:

Scott, surely there will be a big difference as the OM's use a tweeter crossed over at 2.2 Khz! So everything from there up is directed toward the listener. With a full-range, if you use a helper tweeter, it will typically come in at around 10 khz. Or have I missed the point?

[Andrewbee]

Scott,

I saw that design thought many years ago. (In a slightly differenent form) the first was in a pair of speakers that were part of a Zenith stereo my mother had in the 70's. The enclosures were cylindrical, can't remeber if there was a bottom but the single ~ 6" driver faced upwards with a white, conical shaped piece of plastic from the middle of the driver that was perhaps a foot or so long. It was not a typical cone shape but maybe an expotential shape? Geez, it was a long time ago.

Dick Olsher also did something similar sans the plastic cone with the Samadhi designs.

That makes an interesting idea but my baffle looks so nice (shameless blowing of ones own horn here ) that I need to get the OB's working properly.

Ron Clarke who posts on the FR forum has been working on a single driver horn with a somewhat similar theme where the driverfront output reflects off of a part of the horn at ~45 degrees.

There was a Lowther cab many years ago which did something like this with I think it was 2 drivers. I can't remember the name presently but it stood on three legs and was corner placed and it regarded as the Lowther cab of all Lowther cabs.

I am short of wood and space to keep these speakers. My "Afterburner" cabs meet their maker this weekend and join the rest of their family in speaker heaven.

Your idea has been done and does work, I am just trying to get away from boxes- horns excepted.


Andrew

[ScottG]

Originally posted by Nuuk


Scott, surely there will be a big difference as the OM's use a tweeter crossed over at 2.2 Khz! So everything from there up is directed toward the listener. With a full-range, if you use a helper tweeter, it will typically come in at around 10 khz. Or have I missed the point?

I've tried discussing the basis behind why this design not only sounds better, but is more accurate - alas, most were too resistive to the idea (either thinking I was bashing SL, or perhaps something even more insidious), or they simple were not interested.. and I didn't want to post a treatise on the subject. (Note the thread was a "Second look at SL's Pluto", or something like that.. in the Loudspeakers section.)

Yes and no (as to the big difference).

You see the B200 has a rising response pretty much where it needs it to give a fairly flat response up to 2kHz+ in this design. Additionally the attenuation at higher levels subjectivly will be lessend because of the reflected energy. Still, you are correct that either a waveguide or an additional tweeter or fullrange (or some combination) will be needed to increase the spl at higher freq.s (or a "filter" which I wouldn't recomend).

Now the OM's do use a tweeter to correct for the loss in spl, but everything from there is not "directed" toward the listener.. at least not as you might think. In truth the Hiquphon tweeter is essentially omni directional up to 8-9 khz. Additionally, because of their low moving mass relative to a midrange or larger driver, the tweeter doesn't pressurize the air the same.

As to the principal of a full-range driver (at least as we accept it here), unless a filter or a waveguide is used, yes - the B200 isn't being utilized as a fullrange driver. Used properly though, it will still have some of the better properties that a good full range driver provides (while significantly suprasing it in many areas).

In particular this driver (used properly) will not need ANY filtering. No high pass, no low pass, not even baffle step compensation (which most fullrange drivers really need - even dipoles, though it isn't baffle step but rather phase cancelation). The loss in spl due to baffle loss is effectivly raised up in freq. and works to provide a low pass character where you would normally cross-over to a tweeter.

Additionally the lower freq. response of the driver "tailored" to the user's needs. If you want dipole operation.. you can have it. If you want an aperiodic box (with perhaps an acoustic high-pass character).. you can choose this instead.