Welcome! Need support, you got it. Or share you ideas and experiences.
In Reply to: RE: A couple Promethius questions posted by driguy on December 16, 2007 at 01:14:49
I'll be using high-level input (just jumpers from the wideband input) but I can connect the L/R as well. Thanks for the tip.
I am hoping it will be easy to get the bass modules to disappear entirely as a sound-source. I am a SD/horn guy and used to perfect coherency.
How well the bass unit integrates depends on many things, one of them is the cross-over frequency. Other ones are the slope of the filter, how the units are placed and, also very important, the sound characteristic of your woofer.
I have Bastanis units playing here since three weeks so I cannot say too much about them yet. But, my previous widerange unit was a Fostex FE208Sigma and this one also roughly goes from 100 to 10,000 Hz. I combined it with three woofers in the same box and with the same adjustable filter.
My first woofer was a Peerless XLS-10, the second a Eton 11-581-Hex and the third a BD-15 (designed by Bert Doppenberg). The first two go to 20 Hz in a 100-ltr box, but cannot be used at frequencies higher than 200 Hz for the Peerless and 800 Hz for the Eton. The BD-15 is larger than the others, needs a box of 160 ltr but starts only 30 Hz due to its very strong magnet. This also gives it a high efficiency (96 dB) and a high useable upper frequency of 4000 Hz. This fast bass respons and its sound character from the paper cone make that it matches very well with wide-range units of similar construction.
Another experience I had was with a downfiring sub-woofer (REL-Stadium II). This unit always gets very high scores in tests, but in my ears it sounded muddy and it made the floor vibrate. Maybe that it nice if you watch DVDs with surround sound, but it has nothing to do with high-end audio. So I turned the REL to its side with the speaker cone sending its sound directly to the listening position and the bass quality strongly improved: much more speed, less vibration. This was at a cross-over frequency of 60 Hz.
So when filtering at 100 Hz I am in favor of placing the bass unit close to the widerange and facing the listener (you probably saw my photos in the next message). The result is that even with my first(!) order filter I have a good integrated sound and a fast and detailed bass. I have no comparison until now with other Bastanis setups where good care has been taken of filtering, placement etc. I compare sometimes with very expensive commercial stuff and I just smile when I hear these.
Anyway you have to try for yourself and that is part of the fun.
the best method to find a perfect woofer integration is to find the best possible baffle position for the stereo image first. Then the phase settings of the woofers has to be done (best is with a helper who turns the phase knob and control the result yourself at listening position). Then turn the crossover frequency low and lift it until you note that the woofers play. From this position go back a little and listen for a while and by switching the plate- amps off you can control if the stereo imaging is affected by the woofers. When you can`t find the ideal setup this way you can try another firing direction for the woofers or another placement in the room. The possibility to place the woofers separate from the baffles allows maximum flexibility to find the best place for imaging (baffles) and woofer integration even in rooms where passive speakers have no chance to sound satisfying.
The active powered woofers make it very easy to get enough bass to fill up the baffles but without perfect matching by the listener there will always be an imperfection which reduces the quality of the speakers a lot.
When you control the quality of the stereo image of the baffles with and without the woofers and there are no or minor differencies (in the best case, possible in some rooms only, the imaging can take profit from the woofers)the woofers integrate perfect.
@ Eddie: The Bastanis woofers are a perfect match to the open baffles, i second your experience that woofers with wideband characteristics are important...
I agree that Robert's method is the ideal, but in my case very unpractical. My bass units are directed along the diagonal of the room and tilted backwards to use the longest distance available. In this way there is no single lowest resonance frequency. I first had my bass units parallel with the back wall. This gave a very strong and irritating resonance at 39 Hz, which exactly matched the distance of the speaker to the opposite wall. With the speakers along the diagonal the resonance is smeared out in the range of 30 to 35 Hz but far less pronounced and not irritating.
Playing around with the bass filter is also very unhandy for me because I built it in to my amplifier. I once tried to combine the filter with a phase shifter. Unfortunately, both parts worked fine separately but when combined they influenced each other and could not be used. Two solutions for very flexible matching are available. The first one is to use a Behringer DCX2496 but this will degrade the sound. Even better is to go fully digital, e.g. with brutefir but that is a lot of work.
when you use digital sources best is you go fully digital and convert to analog signal in the power- amp. This method keeps the signal untouched as long as possible and with the right software you can do all kind of corrections without reducing the quality of the signal. Before you use the digital correction features try to reduce the physical failures of your setup - you can digitally flatten a room resonance very easy but because the resonance physically still exists the echo of the resonance will still be there when you make a correction for the amplitude. When you are not shure how to make measurements for the digital room corrections i can give you some further advice per p.n.
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