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In Reply to: RE: Beaming/shouting posted by Robert Bastani on April 23, 2009 at 23:46:55
Well, after playing around with various placements to no avail I found out that the "ringing"/peaking on certain continuous notes is connected with the large patio double glazed sliding doors behind my listening position.When I open them (they can only open by sliding one behind the other so I cannot get 100% open space) the peaking reduces a lot.I played some pink noise test tones and the problem is obvious around 500-1000hz only which is quite high for standing waves.Maybe its a comb filter effect but treating the back wall behind the speakers with some diffusers did not cure this unless it is a resonance of the glass itself which is excited directly from the widebands.Some simple curtain rollers in front of the sliding doors did not do much either so the next minimal invasion technique is to coat the glass doors with something like the 3m security film for windows .Maybe this will damp the resonance if that is what is happening.Otherwise will need expensive double curtains.
By using diffusers behind the speakers the soundstage is better though and as it is with the curtain rollers-less echo in the high frequencies I guess..Cheap diffuser trick is to get some polyester fiber panels used in building as heat isolation.They are more user friendly than fibreglass but of course you have to cover them with a fabric for something presentable.
Otherwise I found a very friendly company here in Greece (iselco.gr) that manufactures diffusor panels looking like wood or marble that are reasonable priced i.e.45 euro p.sq.m.Four 120X60x3cm panels would cost like 140 euro which is not bad compared to the hi-end offerings.Funny thing with all this is that I still dont know why with the other speakers I did not get the same problem unless it has something to do with different room nodes excited by the dipole widebands.
So keep trying.....Robert, regarding the rusting I of course did mention that I lived (not now) opposite the beach and the climate was understandably quite corrosive.However I was disappointed that the paint job hardly lasted 6 months.Perhaps Eminence do not sell comparatively a lot of open panel speakers that are more exposed to oxidization than closed baffle and so their quality level is geared to that end.I do not know how many Bastanis users are situated close to the ocean in a humid environment -probably not a lot.
Also ,do you recommend using something like the behringer equalizer to smooth out the bass frequencies only? It has an RTA so this helps and quite precise adjustments.
Edits: 04/29/09 04/29/09
I'll leave the expert replies to Robert but I've a couple of comments:
1) normal box speakers may not excite the same room issues due to dispersion characteristics and the way box speakers vs OBs energise the room with sound.
2) I used the Behringer for sometime with great success. The controls are not exactly intuitive though. I would add that the RTA may not be accurate enough at bass frequencies, even the manual states this - instead I used the XTZ room analyser. I have moved over the integrated the XTZ Sub Amp 1 DSP plus the room analyser. You can find a writeup of my experiences at www.enjoythemusic.com, the XTZ is much easier to use and in the end you get a better result.
It is hard to know whether my problem is a room node or a glass resonance.
Regarding the XTZ/Behringer , I have read your review but the behringer I think is much cheaper (350 usd vs 1000usd?)and does not need one to change the sysstem from active subs etc.You just connect it between the preamp and the subs as they are.
Certainly the Behringer is much cheaper if you have the bass amps already or don't have any need to change them. If you use the RTA you'll need the Behringer or similar mic as well. The XTZ room analyzer is quite a bit more expensive than the Behringer mic but it gives you a better feel for what is happening in the bass.
The RTA in the XTZ or Behringer RTA may help you track down you patio door glass problem. I find being able to measure the room removes a lot of highly subjective guesswork. The freq seems high to be a room mode as such but I suppose it could be the res freq of the glass itself.
Actually I bought the XTZ room analyzer, mainly because of your review even though the behringer is an all in one solution (RTA/equalizer).I have not used the xtz yet it yet but it seems more detailed in the bass RTA so I was thinking of getting the behringer and combining the two for solving some of the bass problems.The behringer can adjust the bass frq quite well with the parametric eq as I see it, right?
Would this be a worthwhile upgrade for the bass?
What you are planning to do is exactly what I used for several months very successfully. I used a combination of PEQ and GEQ, you should indeed get more accurate results with the PEQ but use what works for you. Assuming you have a room with room modes to tame (ie it's not HUGE)then it's a significant improvement to the bass performance of your room/system but the degree does of course depend on how your room measures in the first place.
Take some measurements first to find out how the room performs. In my room I used 3 position measurements to begin with but when doing the fine-tuning I used single position measurement, it's much faster and in my situation there was little difference between 1 and 3 position.
With the room analyzer and DEQ2496 it took me 2 to 3 hours to get a good result once I had opimized subwoofer placement - which ended up being exactly when I had them in the first place! With the XTZ Sub Amp 1 I got a flatter response due to the room analyzer programming the dsp for me but you will get a good setup with the DEQ2496 too.
Drat!
After further investigation I have come back full circle to the widebanders.Putting pink noise around 800hz and moving very close behind the widebanders the ringing is very pronounced so no way it is a room node or resonance somewhere else in the room.The effect is more pronounced behind the speakers than in the front.If you stand back a bit or even from the listening position this peaking or ringing has a "phasey " quality so you cannot really tell from where in the room it is coming from.
So perhaps Robert is right and the speaker has changed characteristics and the damping process has "worn out" and the speaker is resonating .
Robert, what are the problem frequencies that you cure with the damping process?
I guess I will have to get some new widebanders and keep my fingers crossed that that will be the end of it.
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