Horn design question

[Archaea]

I have a friend at work who states that a horn design doesn't have to be perfectly sealed, and it will work just fine.  He says a subwoofer enclosure just isn't that sensitive to minor air leaks.  He and his dad owned a car audio business years ago, and said you wouldn't even need to use any type of sealant.  He said they used to build their ported boxes with 1/4 crown staples, no glue, and and no sealent with the particle board they built cabs with and the product worked fine with 1000 watt 12" subs, and customers never had problems.

 

Thoughts?

 

 

 

[Ricci]

Thoughts? Have these guys ever built a horn or designed one? Thought #2=LOL

[chrapladm]

WOW......WOW......I cant believe anyone who made a living building speakers boxes would say that. Someone else to add to the list of whom never to buy from.

 

1/4 staple and no glue thats just crap. I have built a few boxes inmy time and one with leaks verse one without for me is night and day. That being said some subwoofers with leaks, be it horned or not, have added noise because of the air leaking. Which in turn, because of the leaking air, is robbing you of SPL.

 

The reason why most people ue PL glue when building a horn is becaue the glue expands and makes sealing the cabinet from any air leaks much easier to do in ll the joins. Controlling the air flow in any design is paramount in my eyes. Sealed ported or horned.

 

And then to say it worked fine with a 1000watt sub means nothing. You can have a sub in a cardboard box in a trunk with an amp and it will "work." Can it sound better yes but it does "work. "

[Madaeel]

I had minor air leaks on my SI cabs and my response dropped like a rock around 30-32hz. Basically they acted like a ported sub with no benefit of the tune. I dont know much about DIY but I know those guys are idiots.

[Kvalsvoll]

That is wrong, it is not unusual to observe very high pressure at the throat end on a bass horn, and even a small leak can have significant effect on performance and there will be audible noise.

[Infrasonic]

I have a friend at work who states that a horn design doesn't have to be perfectly sealed, and it will work just fine.  He says a subwoofer enclosure just isn't that sensitive to minor air leaks.  He and his dad owned a car audio business years ago, and said you wouldn't even need to use any type of sealant.  He said they used to build their ported boxes with 1/4 crown staples, no glue, and and no sealent with the particle board they built cabs with and the product worked fine with 1000 watt 12" subs, and customers never had problems.

 

Thoughts?

 

 

Ugh.

 

No, just .... no.

[Archaea]

He's going to register an account and plea his case he told me.   He thinks "you all knuckleheads" (typical phrase he uses) are wrong. 

 

If he tries to change his story I'm going to call him out.  We've argued about this for months. I had him approve my original post as neutral before I posted it so it could be evaluted as it was without trying to bias the question.  He's probably writing up his defensive dissertation as we speak. 

 

He told me that people in real life can't hear an air leak like that, that even if it could be measured it wouldn't be noticable.  This afternoon, he assured me he could drill a 1/16" hole in one of my 18" sealed UM18-22 cabinets and I wouldn't hear it, or be able to even tell.  I told him I would absolutely hear it because it would whistle Dixie when I turned my subs up.  (I had three of my sealed subs not seal on the first attempt at moutning, and you could easily hear the air whistling behind the rubber gasket! - so I know the cab seal is important!)

I told him - - - perhaps if you are running some sort of low excursion radio shack subwoofer driver you might not notice air leaks, but with a high excursion woofer or a powerhouse horn sub  you are going to notice an air leak easily.  The lil mike designed F20 horn pair I heard at HuskerOmaha's meet in 2011 didn't sound that great to me, they were muddy and exhibited ringing.  I was told they had air leaks and that the next owner resealed, and retighted all the panels and it supposedly made a big difference.  I didn't hear them again to compare, but I was curious how much difference that made.  I know with sealed subwoofers a leak matters - both by slightly (or more - depending on leak) changing frequency response, and by the whistle, air rush sound that occurs.  I've read some of the horn subs like the gjallarhorn build up pretty impressive pressure in the horn path - so I'd have to figure sealing is fairly critical.  My friend commented today there is no way it would matter with a horn sub because it's basically a ported sub and you'd never notice with a ported sub.   He jokingly said he was going to build two gjallarhorns and seal the joints on one, and not seal the joints on the other and I'd never be able to tell which was which by ear.

 

Oh and just to put things in perspective.  He said they did seal some of the panels at their shop when the customer specifically requested it or paid for it, but otherwise they didn't - because it didn't matter.  If they needed to seal a sub at customer request, they would use a hot glue gun to seal the panels, and just the rear panels, because you couldn't get to the front panels when the box was put together.  I'm not making this up.

 

 

Defend away good buddy...

[Wraith Leader]

He's going to register an account and plea his case he told me.   He thinks "you all knuckleheads" (typical phrase he uses) are wrong. 

 

If he tries to change his story I'm going to call him out.  We've argued about this for months. I had him approve my original post as neutral before I posted it so it could be evaluted as it was without trying to bias the question.  He's probably writing up his defensive dissertation as we speak. 

 

He told me that people in real life can't hear an air leak like that, that even if it could be measured it wouldn't be noticable.  This afternoon, he assured me he could drill a 1/16" hole in one of my 18" sealed UM18-22 cabinets and I wouldn't hear it, or be able to even tell.  I told him I would absolutely hear it because it would whistle Dixie when I turned my subs up.  (I had three of my sealed subs not seal on the first attempt at moutning, and you could easily hear the air whistling behind the rubber gasket! - so I know the cab seal is important!)

 

I told him - - - perhaps if you are running some sort of low excursion radio shack subwoofer driver you might not notice air leaks, but with a high excursion woofer or a powerhouse horn sub  you are going to notice an air leak easily.  The lil mike designed F20 horn pair I heard at HuskerOmaha's meet in 2011 didn't sound that great to me, they were muddy and exhibited ringing.  I was told they had air leaks and that the next owner resealed, and retighted all the panels and it supposedly made a big difference.  I didn't hear them again to compare, but I was curious how much difference that made.  I know with sealed subwoofers a leak matters - both by slightly (or more - depending on leak) changing frequency response, and by the whistle, air rush sound that occurs.  I've read some of the horn subs like the gjallarhorn build up pretty impressive pressure in the horn path - so I'd have to figure sealing is fairly critical.  My friend commented today there is no way it would matter with a horn sub because it's basically a ported sub and you'd never notice with a ported sub.   He jokingly said he was going to build two gjallarhorns and seal the joints on one, and not seal the joints on the other and I'd never be able to tell which was which by ear.

 

Oh and just to put things in perspective.  He said they did seal some of the panels at their shop when the customer specifically requested it or paid for it, but otherwise they didn't - because it didn't matter.  If they needed to seal a sub at customer request, they would use a hot glue gun to seal the panels, and just the rear panels, because you couldn't get to the front panels when the box was put together.  I'm not making this up.

 

 

Defend away good buddy...

Hello everyone,

 

DIY Idiot here. :-)

 

Glad you all can have some fun at my expense. I was going to try and put things into perspective, but seems like you all have your minds made up, and would just ridicule anyway. I may or may not spend my time explaining the actual content of my argument at a later time, or the fact that I was being facetious about drilling holes in sealed subs, and not being able to tell the difference. The "argument" keeps getting brought up... but not by me. I conceded that I got of the AV game 15+ years ago. I conceded that my knowledge was mainly in Car Audio and PA systems for churches and schools. I conceded that I did not work on the "high end" competition audio myself, but was aware of it, and was intrigued by it. My only point is, and always has been, that the average person, will not be able to pick out the difference between two boxes that I would build where I specifically sealed one, and didn't the other.

 

Have fun. I know you are all rolling your eyes in disdain at me right now. :-D

 

Just my $.02

 

[Infrasonic]

"...seems like you all have your minds made up..."

 

I didn't make it up. Physical reality did. Airleaks can cause all sorts of issues including: loss of efficiency and actual noise.

 

It's easy to mask the noise made by a leaky enclosure when it's in the trunk of a car in an audio system that has it's noise floor obscured by road noise. Bring a leaky subwoofer enclosure inside a home and that whistle and squeaking sound of an air leak will drive one mad.

 

An even worse leak can bring down the efficiency of the system as well but it had have to be a pretty bad leak.

 

I'm happy for you that your clients did not seem to mind but that isn't really saying much either. As much as it pains me to sound like an a-hole like I am now but it's true.  

 

 

 

All of what I said completely ignores the complications an airleak will have on a resonant system, horn or not.

[MKtheater]

I had air leaks in my baffle wall and it kind of acted like a very low tuned ported sub I thought! Once I sealed it up the bass was much more tactile and the low end creates more pressure! No leaky subs for me.

[Archaea]

Wraith Leader,

 

What?  No long explanation!?!?!?  How very disappointing! 

 

What if you post your logic and everyone comes alongside you???      You should try it!

 

Listen, I figured out how we can test your air leak theory.  I'll have you and your family over for dinner and a movie, You can take one of my mounting screws out of one of my sealed cabs and not tell me which one.  Then we'll see if anyone can detect which cab has the missing mount screw.

[lukeamdman]

Wraith Leader,

 

Have you ever designed and/or built a horn subwoofer?

[Madaeel]

It's easy to mask the noise made by a leaky enclosure when it's in the trunk of a car in an audio system that has it's noise floor obscured by road noise. Bring a leaky subwoofer enclosure inside a home and that whistle and squeaking sound of an air leak will drive one mad.

I think maybe this is the main problem. If he hasn't been involved in HT for 15 years then honestly he has no idea what it would sound like or the problems it would cause. Like you said cars have rattles, road noise etc and between that and usually the levels we listen at, no way you're hearing a leak.

 

I will say I never heard the leaks in my sealed cabs until they tried to play below 30hz so he is right you might not hear it on a sealed sub if you're listening to music but it definitely has detrimental effects the lower in frequency you go and I can only imagine what it would do to a resonant system.

[Wraith Leader]

To all,
I have never myself designed a horn loaded subwoofer. My dad has, and has been making speaker enclosures for over 35 years. I have designed and built full-range/tower horns however. I really take offense to the " Someone else to add to the list of whom never to buy from." comment. I love how the Internet gives people omniscience regarding the background of people and all the context around their statements. :-)

 

I have designed a number of systems over the years, and no, they were probably not up to the standards of this and other forums like it, but they served their purpose, and were not ridiculously overpriced. I know I will be in the minority on this forum, but I am okay with that.

For a little context: This "argument" started awhile back when I made comment to the effect of my dad or I could build a cabinet for less than most of the pre-made options. I was asked if I thought I had the skill to cut the box to the proper tolerances and properly seal it. I mentioned that when we made boxes they were built well enough not to be sealed. The infamous "Audiophile Angst" reared its ugly head, and I was immediately chided for my obvious ignorance. I did admit that "in my day" we didn't have 4" excursion subwoofers, and that I dealt primarily in Car Audio with some PA equipment as well. Most of the boxes we built with either sealed enclosures for low-end 6x9 or 6-10" woofers or ported for larger ones. We built them well enough that they were basically airtight, and we NEVER had any complaints about "whistles" or "air leak" noise, etc. We had to start "sealing" our boxes because someone convinced the dealers that running a bead of hot melt glue on 8 of the 12 inside seams actually made a difference on $20 10" "subs". We said they were crazy and demonstrated. Our distributer said the customer wanted them built like this, and we obliged. Most of our enclosures were 1/2" particle board, some of the bigger ones (12" and up) were made with 3/4" particle. In the late 80's/early 90's the demand for MDF arose, and we started making more of the larger sub enclosures from that. For the particle board, we would use 1-3/4" long pre-glued 1/4" crown staples about every 4"-6". For the MDF we would use wood glue on the seams and brad nail them. Some of the custom work we did involved silicon sealing the boxes, but we found wood glue and MDF sufficient for most applications.

I know about tuning boxes using volume and port specs. My dad and I used to design enclosures as a hobby. Some of them we actually ended up making. One of my favorites was a dual 15" folded horn that was the sole enclosure used in a 300-400 seat auditorium. There was nothing but good comments from the customer about the sound quality or aesthetics of the speaker. We installed the entire sound system, and picked up 3 more jobs by word of mouth. I could care less what your meters tell you about the SPL level of the box. The most important thing to us was our customer's satisfaction.

I guess I have typed enough for now. Fire away, and let the vitriol commence. :-)
I still stand by my statement, that the average listener cannot tell the difference between a ported/vented/hornloaded enclosure that has been "properly sealed" to the exact same enclosure that is airtight enough because it has been well-built.

Take life seriously, not the Internet. :-)


 

[maxmercy]

Proper MDF and wood glue construction will do the job.  But when building a complex horn (or anything else) where you will not be able to get to the seams later, it seems reasonable to use an expanding glue or seal as you go.

 

You said that most people wouldn't be able to tell the difference.  This forum is not populated by 'most people'.  It does have those who required and have designed and built equipment to reproduce the most challenging content out there.  

 

I would stop posting here if this forum became populated by 'most people'.  Way too much to bother with.

 

JSS 

[MemX]

If anyone has the time and spare money, it would be interesting to test the theory by buying one of those super-cheap car audio sealed subs for a few tens of dollars - then you could drill holes in it one by one and re-measure each time.

[BeastAudio]

That would be fun honestly. Let's also keep in mind, we are sitting here thinking about not having one of our massive stroke 18" subs sealed, but Wraith is talking along the lines of a 6 or 10" subwoofer he would use in a car. The displacement and capability differences are magnitudes different as we all know, and not having a properly sealed 18 with 4" of stroke would exacerbate the problems evident from not getting a good seal....

[lukeamdman]

My only experience with an improperly sealed enclosure is when I was 16.  I didn't know a thing about what I was doing, but I bought a cheap 1cu.ft sealed box off the internet and a Audiobahn AWT12X 12" driver.  

 

My untrained ears told me something didn't sound right, and pushing the cone, I could tell from the resistance that something wan't sealed right.  Sealed to me at the time meant the enclosure should be sealed...

 

I "borrowed" some PL400 from my dad and put a bead of glue on each seam inside the box and waited 24 hours.  Bingo, problem solved.

 

 

 

Now, that was a pathetic 12" driver with ~500w of power.  What do you think will happen with a 18" LMS 5400 or UXL-18 in a horn with 4,000+ watts?  Horns generate internal pressures far beyond a vented box, let alone sealed.  

 

Dustin, stormwind13 on AVS, has 15" driver folded horns named the F-20.  He had issues from the drivers sealed chamber not being sealed, and that 15" driver isn't very beefy at all.  

[Wraith Leader]

I want to make sure we are talking about the same thing. I never said air leaks were okay. I have also conceded that high-end 18"+ 4"excursion subwoofers horn-loaded for Home Theatre are outside my area of expertise. I have maintained (over the course of a year or so) that it is not necessary to seal the VENTED portion of the enclosure beyond the normal good construction. Of course you cannot drill holes in the sealed chamber. When I said that to Archaea I was "grenade throwing" after he brought up the argument yet again, and then posted his original statement on this thread. To be perfectly honest, I had thought about posting blatantly false information to see you all go apoplectic. However, that choice was taken from me with Archaea's second post with my comments taken out of context. I was speaking about my experience with car audio in general, and he extrapolated that to a definitive statement about horn speakers in particular. The only way to really prove myself would be build a horn enclosure to spec, and not "seal" it. This is not something I am in a position to do at this time. I have neither the funds nor facilities at this time for such an endeavor. So I guess we will have to keep up the friendly banter until that can happen.
 

Honest question...
How do you get an even bead of silicon (or favorite "sealing" adhesive) along every seam? I assume that you would agree that an uneven bead/excessive amount of sealant would change the tonal characteristics of the box as much as any microscopic void left between the wood seams. Also did you account for the reduction in vent surface area or chamber volume? I am sure that you would agree that those two items do play into the tuning of an enclosures chambers.  :-)


 

[BeastAudio]

The second paragraph must be your venture into "Blatantly false information." Yes I do typically factor in 0.02 cuft for adhesive in the box when aiming for exact port tuning   

[chrapladm]

Did someone make an account and is just pulling our leg?

 

How much adhesive is someone going to use to change the "sound," of the cabinet.

 

Beast is .02cuft for a 5mm bead using PL or is that a 6mm bead?

[BeastAudio]

Looked kinda like this:

 

[Archaea]

Wraith Leader,

 

What, pray tell, was out of context in what I've said?

[Shredhead]

Best enclosure for subwoofer:

You haven't heard bass until you get that cardboard tone.  

[Wraith Leader]

Wraith Leader,

 

What, pray tell, was out of context in what I've said?

 

You made it seem like my comments about our "run of the mill" enclosures were meant for any and all setups. I have in the past freely admitted that my knowledge is limited. I still maintained the fact that most people could not tell the difference if an enclosure had microscopic air voids, and if those voids were "properly sealed". I never said you could have "air leaks" or gaping holes that would whistle.

 

Based on the comments here, I am too lowly to step into the presence of so wise and knowledgeable beings. I will remove myself from these proceedings, but I may peek in from time to time to remember my shame and humiliation.