I have visaton b200 on a square 40 inch piece of mdf. The size of the mdf delays the back radiation from meeting with the front radiation, so that when they do meet they are no longer out of phase and low end performance is improved.
What do you think about placing the visaton in a long tube, so the length of the tube delays the back radiation. Would this work and would it compare well against the standard baffle type board. I'm guessing tube resonance may decrease overall sound quality, but how bad. Any thoughts?
Many thanks. John
What do you think about placing the visaton in a long tube, so the length of the tube delays the back radiation. Would this work and would it compare well against the standard baffle type board. I'm guessing tube resonance may decrease overall sound quality, but how bad. Any thoughts?
Many thanks. John
The tube would increase the delay of the rear wave, but it would be have to be rather long to be effective (similar length as baffle width or longer). The associated resonances might indeed not be nice in this combination. Can you make the baffle larger instead?
That creates a horn effect and I think is called aperiodic loading, Google it , I think you need to damp it as well.
1. Thanks, did you say larger baffle, is 40 inch not big enough.
2. When you say the tube would have to be long, how long to get down to 100hz
3. What kind of dampers for the tube, bitumen pads possibly
2. When you say the tube would have to be long, how long to get down to 100hz
3. What kind of dampers for the tube, bitumen pads possibly
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Big enough for what? Read up on open baffle theory to understand how baffle dimensions relate to frequency response etc. I'd recommend the descriptions by Siegfried Linkwitz.
The delay of the rear wave relative to the front wave is what controls the cut-off frequency. You'd have to figure out the combined delay of the baffle + tube. This depends on the 3D geometry of the whole set up. Again, read up on open baffle theory and you'll understand. Linkwitz also describes the H-baffle, which is a bit similar to what you are describing.
Dampers for what? Bitumen pads will add weight to the tube walls. That may be useful to reduce vibrations of the tube walls. Is this what you're aiming for?
Yes, this is the most basic principle of dipolar response.
How long, and what other dimensions? A tube open at one end and closed at the other is a quarter wave resonator. It will resonate at a frequency that is defined by axial length and any taper present, and for untapered pipes at the odd harmonics thereof (I haven't mentioned end-correction, but we'll set that aside for present).
Yes, but you also need to define your criteria / design objectives for tuning, since tuning frequencies and box sizes pulled out of the air will not provide quality performance in this, or any other type of enclosure. A loudspeaker is a combined system of driver and cabinet / baffle, so it is largely system response you work with.
Depends what you mean by 'compare well'. It's different. In essence this is what an open-back box or U-frame is, although those are typically quite short. The polar response changes depending on extremity, moving from the classical figure-8 toward something approaching (but not quite) a cardioid in the LF. They can be highly effective if properly designed / exploited.
See above.
Information on baffles:
Linkwitz Lab - Loudspeaker Design
Offerings
OB Theory
I think you can only get the waves 'in sync' by having different path lengths?
And for different frequencies the difference in length would need to vary, too.
The Visaton is a truly great driver, but basically it's a midrange. A wideband/midrange.
Not at ease on the 10th octave (10-20khz) and sure as hell not at ease in the first 3 (20-160hz)
Was not even able to do nothing using EQ!
Not at ease on the 10th octave (10-20khz) and sure as hell not at ease in the first 3 (20-160hz)
Was not even able to do nothing using EQ!
I think there is NO way to get any decent bass from that driver, no matter which enclosure you'd use.
The only way you might get something out of it is by using several of them, then apply a high-shelf negative EQ of about 15db starting 1khz, then boosting the low-end until there is no traction anymore. Which will come pretty fast given the Fs and limited xmax.
Let me know, i have several of them left unused here! 😛
As Scott says using a tube converts it to a TL, and given the high Q (why it is usually in an OB), it will need to be damped aperiodically.
Despite what Jon says, B200 can produce bass, its real problem in stock form is the rising topped. ie it is not the case that it doesn’t produce bass, but that it has a runaway topped. The simple expedient of adding phase plugs cures most of the top end issues or one could use DSP or analog EQ but that, unlike the phase plugs, does not sort the dispersion issues at HF. Rated at 95 dB the driver is really closer to 90 dB once the top is tamed.
It should be noted that Bert Doppenberg used a pair of these with the small Feastrex in a very pretty pyramidal/3 triangle OB, Joe Rasmussen used it in an aperiodic TL as part of a 2-way (rolling off the top and adding a midTweeter or tweeter also sorts the HF issues). We used it in a 1.3m wide by 1.1m tall OB and got acceptable bass (with phase plugs)
dave
Despite what Jon says, B200 can produce bass, its real problem in stock form is the rising topped. ie it is not the case that it doesn’t produce bass, but that it has a runaway topped. The simple expedient of adding phase plugs cures most of the top end issues or one could use DSP or analog EQ but that, unlike the phase plugs, does not sort the dispersion issues at HF. Rated at 95 dB the driver is really closer to 90 dB once the top is tamed.
It should be noted that Bert Doppenberg used a pair of these with the small Feastrex in a very pretty pyramidal/3 triangle OB, Joe Rasmussen used it in an aperiodic TL as part of a 2-way (rolling off the top and adding a midTweeter or tweeter also sorts the HF issues). We used it in a 1.3m wide by 1.1m tall OB and got acceptable bass (with phase plugs)
dave
I ran b200's for 10 years on OB. I used them in 36x48 baffles. I used Planet_10 phase plugs and really liked them.
I eventually biamped with 12 inch woofers on the same baffle. Better bass but some added vibration complications to the sound from the Visatons.
Overall I found them excellent 100Hz and up on a large baffle.
I eventually biamped with 12 inch woofers on the same baffle. Better bass but some added vibration complications to the sound from the Visatons.
Overall I found them excellent 100Hz and up on a large baffle.
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