Why not more talk about Waveguide damping and/or foam inserts - Page 4 - AVS Forum
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DIY Speakers and Subs > Why not more talk about Waveguide damping and/or foam inserts
arnyk's Avatar arnyk 07:20 AM 08-05-2013
Quote:
Originally Posted by Bill Fitzmaurice View Post

Quote:
Originally Posted by mastermaybe View Post

"Probably not" what?
It's exactly what I was getting at...the near field monitors are not horn designs- it's clear in all of the pictures.
Of course not. Near fields require that the wave fronts from the drivers fully integrate well before the listening position. That requires that they have very wide dispersion, especially on the vertical plane. Most horns have narrow dispersion on the vertical plane, so the wave front integration distance is too long for them to be employed as near fields. The exception would be short horns with round mouths, which often are referred to as waveguides, though in truth more often than not said waveguides are, in fact, horns.

Where I come from waveguide and horn are pretty much treated as synonyms. AFAIK all horns are waveguides but not all waveguides are horns. Waveguide sounds more professional than "horn".

I first heard the term waveguide used this way by Earl Geddes in the 1980s back when he worked for Ford, if memory serves.

goonstopher's Avatar goonstopher 09:48 AM 08-05-2013
Should I use silicone to seal in the ports?
Bill Fitzmaurice's Avatar Bill Fitzmaurice 01:12 PM 08-05-2013
Quote:
Originally Posted by arnyk View Post

Where I come from waveguide and horn are pretty much treated as synonyms. AFAIK all horns are waveguides but not all waveguides are horns. Waveguide sounds more professional than "horn".

I first heard the term waveguide used this way by Earl Geddes in the 1980s back when he worked for Ford, if memory serves.
It seems that the definition varies from person to person, company to company, especially as concerns not wanting to use the dreaded 'H' word for purely marketing reasons. IMO if it has gain, it's a horn.
coctostan's Avatar coctostan 02:33 PM 08-05-2013
Quote:
Originally Posted by Bill Fitzmaurice View Post

It seems that the definition varies from person to person, company to company, especially as concerns not wanting to use the dreaded 'H' word for purely marketing reasons. IMO if it has gain, it's a horn.

The fact is that even a "waveguide" has gain. Put a CD on a flat baffle and compare it to a Geddes style oblate spheroid or a simple 90deg conical horn. A flat baffle is just a 180deg waveguide. A CD horn doesn't have enough gain or progressively increasing at HF gain to make a compression driver flat, that is true.
Bill Fitzmaurice's Avatar Bill Fitzmaurice 02:59 PM 08-05-2013
Quote:
Originally Posted by coctostan View Post

The fact is that even a "waveguide" has gain. Put a CD on a flat baffle and compare it to a Geddes style oblate spheroid or a simple 90deg conical horn. A flat baffle is just a 180deg waveguide. A CD horn doesn't have enough gain or progressively increasing at HF gain to make a compression driver flat, that is true.
Don't confuse gain with spatial loading, which is the reason for even a flat baffle having 'waveguide' characteristics.
Thatsnasty's Avatar Thatsnasty 03:57 PM 08-05-2013
Quote:
Originally Posted by Martycool007 View Post

I have read that it is a good idea to add some sort of mass to the outer side of the waveguide or horn. I have seen people use a thick heavy mass dampened tape. I would imagine that by adding some mass to the waveguide/horn would help keep the waveguide/horn from any type of possible vibrations.

I used rope caulk for my 4Pi' build. Wrapped all the back of the horns with it, mushed it into place and used a bit of duct tape over top to keep it secure.
I didn't ever have an issue with sound quality, in fact, quite the opposite.
The horns / speakers always sounded amazing, I just figured I'd do it while I had the chance.... snake oil? Won't really know unless I do measurements.
Bill Fitzmaurice's Avatar Bill Fitzmaurice 04:15 PM 08-05-2013
Quote:
Originally Posted by Thatsnasty View Post

I used rope caulk for my 4Pi' build. Wrapped all the back of the horns with it, mushed it into place and used a bit of duct tape over top to keep it secure.
I didn't ever have an issue with sound quality, in fact, quite the opposite.
The horns / speakers always sounded amazing, I just figured I'd do it while I had the chance.... snake oil? Won't really know unless I do measurements.
+1. Well made horns don't need special damping to work better, because they don't vibrate. Just as is the case with different cone/diaphragm materials horns don't inherently have coloration or a signature sound, unless you hit them with a stick. Cheap horns can vibrate, usually not from the internal pressures placed on them by their own drivers, but by the external pressures placed on them by the woofer rear wave output when mounted in the same cab without being isolated.
rajacat's Avatar rajacat 06:11 PM 08-05-2013
I'm going to wrap my SEOS-18's because it's relatively easy and cheap. Why not go to the max for sound quality even though it might not make a noticeable difference? Then again it might. No point taking chances.biggrin.gif If the WG was made out of concrete then then it would probably be absurd. I'll have a lot of labor tied up in these speakers so if its an easy tweak, I'll do it.
goonstopher's Avatar goonstopher 06:19 PM 08-05-2013
I put together the Alchemy 8's and they sound completely broken its far away actually painful and the entire woofer sound is off. this is way over my head I don't know how to get these done
tuxedocivic's Avatar tuxedocivic 10:51 PM 08-05-2013
Having some bad luck goonstopher. Has someone vetted your cross overs for the Fusion 8s? I wonder if there's an error in that one also.
Mike-ht's Avatar Mike-ht 11:46 PM 08-05-2013
Maybe something wrong external to the speakers? What are you powering these with? Is is possible there is some type of auto-eq is set for different speakers? Maybe too much heat applied to the components when putting the crossover together?
goonstopher's Avatar goonstopher 04:42 AM 08-06-2013
Quote:
Originally Posted by tuxedocivic View Post

Having some bad luck goonstopher. Has someone vetted your cross overs for the Fusion 8s? I wonder if there's an error in that one also.

MTG did but who knows... These are broken
goonstopher's Avatar goonstopher 08:19 AM 08-06-2013
Quote:
Originally Posted by Mike-ht View Post

Maybe something wrong external to the speakers? What are you powering these with? Is is possible there is some type of auto-eq is set for different speakers? Maybe too much heat applied to the components when putting the crossover together?

There is no EQ on them and my old Behringer b2030p's still sound good since I'm forced to use them.

Too much heat is possible though
tuxedocivic's Avatar tuxedocivic 09:50 AM 08-06-2013
Well there's no way you received 5 bad woofers, so I'm guessing a XO problem. I can't think of anything else unless your subjective tastes are such that you find they sound "broken". Could be, but I doubt they sound so different from the Behringers that one would sound great and the other broken. So I'm not sure what to think.

At least we can rule out that it's the Fusion Max. So switching to the Pure might not be the best idea if it'll end up costing you more.
Erich H's Avatar Erich H 09:56 AM 08-06-2013
I think we can pretty much rule out the woofers or compression drivers. And the designs got good reviews at the get together a couple months ago. So that brings it down to some issues with building the crossovers. DIY has a learning curve for everyone, but the good thing is that there are always a lot of people willing to help get it done.

MTG-90 will be assembling his crossovers. I'm sending parts to him today.
goonstopher's Avatar goonstopher 10:15 AM 08-06-2013
Quote:
Originally Posted by tuxedocivic View Post

Well there's no way you received 5 bad woofers, so I'm guessing a XO problem. I can't think of anything else unless your subjective tastes are such that you find they sound "broken". Could be, but I doubt they sound so different from the Behringers that one would sound great and the other broken. So I'm not sure what to think.

At least we can rule out that it's the Fusion Max. So switching to the Pure might not be the best idea if it'll end up costing you more.

The max's sound much better then the alchemys. the Alchemys are CLEARLY broken. I am not blaming the speaker... Something isn't right though.

they sound like someone talking in a hallway 100 feet away
JWagstaff's Avatar JWagstaff 10:29 AM 08-06-2013
broken is not the right word to use if it sounds like a hallway.
Eternal Velocity's Avatar Eternal Velocity 10:37 AM 08-06-2013
Quote:
Originally Posted by goonstopher View Post

The max's sound much better then the alchemys. the Alchemys are CLEARLY broken. I am not blaming the speaker... Something isn't right though.

they sound like someone talking in a hallway 100 feet away

The only time i heard anything like this, it was an electronics or source problem... Too much noise floor audibility. I doubt that though, since you've had efficient speakers in your system before. Paper woofers can be noisy in the upper registers, so a crossover issue is definitely a possibility. You hopefully just have your crossover miswired. The worst case Scenario is blown tweeters.
Okv's Avatar Okv 07:43 PM 08-09-2013
Quote:
Originally Posted by MKtheater View Post

I wonder if the horn or CD is really the culprit to people not liking horns. Maybe it is just a bigger woofer playing vocals or higher? Who knows but everyone is different. Has anyone tried the Behringer Truth powered monitors? They are damn good for their price and if you do not want to blast them I bet they would please most.

The issue that started this tread in the first place seems to be lower in frequency - below the cf for the wg/horn.
I have seen others also commenting on similar problems - loud, harsh, annoying sound, somewhere in the midrange frequencies.
(In this particular case I understand there may be issues with the speaker, ie. crossover that causes the speaker to not perform as intended, perhaps we will know when TS reports back.)

So you may be correct in assuming this problem is related to the woofer.
Regardless what is causing it, it will be possible to quantify the problem as something that can be measured and analyzed, and thus, it can also be fixed - for all speaker designs.
I think this can be either a frequency response issue, or time related (ringing/resonance).

I will start a new thread on this.
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