Port Stuffing? - What is best

[ZeosPantera]

I am installing a home theater for a customer upstate. Low Budget

Two of these Audiosource PSW-112 Subs are going to be mounted into mirrored front cabinets. One for .1 the other to support the center channel.

during a round of testing there was some severe "chuffing" coming from the two tiny ports at high volume with ~100hz crossover.

As a quick test I shoved a rolled up pair of socks into each port and that calmed it down a good deal without much of a volume/sound impact. As shoving socks into speakers is not very professional what material would you recommend to lightly stuff the 2x2" ports?

 

[MatthewB.]

I have suggested using blalck socks for years as a cheap way to plug a port. It's cheap, works great and since it's black is not easily seen and is very easy to remove.

 

[Seth=L]

I view what ever cloth thing that may be lying around I don't intend to use for anything as a potential port plugger. I plug ports with old shirts, socks, wool like rags, etc etc.

 

[ZeosPantera]

Gotcha. So cotton, wool or half nylon.

 

[Seth=L]

Gotcha. So cotton, wool or half nylon.

Or whatever makes you happy.

 

[josko]

If plugging up the hole improves sound, why do they build them with ports?
More seriously, can anybody comment on what plugging a port does and under what conditions is it desirable?

 

[davidtwotrees]

Gotcha. So cotton, wool or half nylon.

Stay away from the half nylon-it will seriously compromise the 40-50 hz region. Also, wool should only be used with silver interconnects.

 

[TLS Guy]

If plugging up the hole improves sound, why do they build them with ports?
More seriously, can anybody comment on what plugging a port does and under what conditions is it desirable?

The reason that the port chuffs is that the sub is junk. The ports are not big enough. They sub needed a slot vent with a much higher cross sectional area. It then needs to be longer also. This sub has much too high a port air velocity, and has severe port compression.

In a tuned speaker most of the deep bass emanates from the port. Plugging it will raise F3 and turn the speaker into a leaky sealed unit.

If you want to use that sub turn it down, and play it at a volume were the air velocity is not great enough to chuff. The other option is to buy or build a decent sub.

 

[ZeosPantera]

I am going to try and keep it at a volume where the sock stuffing is unnecessary. The reason I picked such a cheap sub is (1) I had to keep my estimate under my competitions who gave a $4,400 fully installed price and thankfully was overcharging for EVERYTHING. Cant add a thousand dollar sub on the bill if it means I cant eat. (2) It was the only sub I found specifically designed for cabinet mounting.

Just for my future reference does anyone know of another sub (regardless of price) that is designed for cabinet installation (has front adjustments, porting, driver)?

 

[bandphan]

I am going to try and keep it at a volume where the sock stuffing is unnecessary. The reason I picked such a cheap sub is I had to keep my estimate under my competitions who gave a $4,400 installed estimate and thankfully was overcharging for EVERYTHING. Cant add a thousand dollar sub on the bill if it means I cant eat.

Just for my future reference does anyone know of another sub (regardless of price) that is designed for cabinet installation (has front adjustments, porting, driver)?

http://nilesaudio.com/product.php?prodID=Pro15SW&recordID=Professional Cabinet, Home Theater Loudspeakers&categoryID=StageFront&catcdID=13&prdcdID=FG01138

 

[lsiberian]

I am going to try and keep it at a volume where the sock stuffing is unnecessary. The reason I picked such a cheap sub is (1) I had to keep my estimate under my competitions who gave a $4,400 fully installed price and thankfully was overcharging for EVERYTHING. Cant add a thousand dollar sub on the bill if it means I cant eat. (2) It was the only sub I found specifically designed for cabinet mounting.

Just for my future reference does anyone know of another sub (regardless of price) that is designed for cabinet installation (has front adjustments, porting, driver)?

I'd seal the cabinet. It would require you to remove the amp and then carefully seal the ports and any air leaks.

Then I'd add rock wool and bracing to the interior

Just a thought.

If you have the cabinet skills I'd just make your own subs. But that may be too costly.

 

[GlocksRock]

You could also use the Velodyne DLS-R series subs in a cabinet since they are front ported, front firing subs, and have a remote to adjust the volume. The JL subs also fit the bill too, but they are much costlier, and sealed.

 

[TLS Guy]

I am going to try and keep it at a volume where the sock stuffing is unnecessary. The reason I picked such a cheap sub is (1) I had to keep my estimate under my competitions who gave a $4,400 fully installed price and thankfully was overcharging for EVERYTHING. Cant add a thousand dollar sub on the bill if it means I cant eat. (2) It was the only sub I found specifically designed for cabinet mounting.

Just for my future reference does anyone know of another sub (regardless of price) that is designed for cabinet installation (has front adjustments, porting, driver)?

If you are a custom installer, you need to know what is going on.

A vented sub will in general have a higher bass output, for a given power input, and cone excursion. Most of the deep bass comes from the port and not the driver. The sub will roll off at 24 db per octave, but generally taper at a much lower frequency than a sealed sub.

The sealed sub will start cutting off at a higher frequency at 12 db per octave. If the driver is robust enough and has enough linear excursion, then Eq at 12 db per octave at the cut off point can be applied. However this will increase power needs by a factor of four if you apply an octave of Eq. You can not Eq a ported sub, as all you will get is massive cone excursion and distortion.

Take a look at this Shiva driver in a ported enclosure.

Note the frequency and spl curves. Look at vent velocity and cone excursion. You can see that where vent velocity is high (high sound output from the port) the cone displacement is at a minimum. Note how cone displacement rapidly increases as vent air velocity decreases. You will also note a lot of phase shift and time delay.

Now look at the same driver in a sealed enclosure.

Note the higher cut off frequency and that all the output is from the driver, which it has to be. So the back driver sound radiation is lost.

Note that the box is smaller and that the is less phase shift and time delay.

To stop the chuffing you were complaining of you need vent velocities around 18 m/sec or less. As explained before as the area of a port is increased, the port has to lengthen to keep the box tuning frequency the same.

By the way it is not a good idea to put subs in another cabinet. They should be free standing.

 

[lsiberian]

Just my 2 cents

I'd treat this as an infinite baffle situaiton if possible and build the sub into the cabinet using dynamat(or peel-n-seal) to line the box I build within the cabinet. I'd then line it with 4" 6lb rock wool. The idea is to deaden the cabinet as much as possible. Make sure you use brace the cabinet internally some too.

I'd use Shelf style bracing and set the sub in that structure.

 

[ZeosPantera]

I'd treat this as an infinite baffle situaiton if possible and build the sub into the cabinet using dynamat(or peel-n-seal) to line the box I build within the cabinet. I'd then line it with 4" 6lb rock wool. The idea is to deaden the cabinet as much as possible. Make sure you use brace the cabinet internally some too.

I'd use Shelf style bracing and set the sub in that structure.

Interesting idea but again with the cost constraints anything THAT custom would have broke the bank.

That $4400 has to pay for all the labor, Wire including two 25' HDMI's, the ceiling hanging tv bracket, Receiver, Blu-Ray player, IR-Repeater, Universal remote and then the 5.1 speakers.

The customer has absolutely no interest in the system at all. I know that because I would try to explain some options to him and he tells me "look, I dont care about this stuff, all I like is playing poker" then he keeps talking about his $90,000 kitchen cabinets and how much he LOVES GAMBLING and doesn't even have a computer or cell phone.. Wife is a working professional that tells the interior designer all her bad ideas and pays her to listen and agree with all of them. Their 2 kids are 2 and 4 years old so no support there either.

I don't do s***** systems. I refuse. I would suggest a good set of headphones instead of a HT in a box from walmart. Even if it means I don't get paid as much I want to be happy with the results.

Glad I can now come here to vent.

 

[dkane360]

lol u better hope they dont stumble upon this post

The customer has absolutely no interest in the system at all. I know that because I would try to explain some options to him and he tells me "look, I dont care about this stuff, all I like is playing poker" then he keeps talking about his $90,000 kitchen cabinets and how much he LOVES GAMBLING and doesn't even have a computer or cell phone.. Wife is a working professional that tells the interior designer all her bad ideas and pays her to listen and agree with all of them. Their 2 kids are 2 and 4 years old so no support there either.

 

[ZeosPantera]

lol u better hope they dont stumble upon this post

Id say the chances of that are slim to "more likely to raise green pigs on the moon"

At some point I should get a call that the cabinets are done and I can return to putting together a better then average system for people who probably won't appreciate it for years to come.

 

[MatthewB.]

Zeos, just set em up with a Bose system and tell em it's the best and collect your installation fee (in their case 20,000)











btw people like that truly deserve a Bose system.

 

[highfigh]

I am installing a home theater for a customer upstate. Low Budget

Two of these Audiosource PSW-112 Subs are going to be mounted into mirrored front cabinets. One for .1 the other to support the center channel.

during a round of testing there was some severe "chuffing" coming from the two tiny ports at high volume with ~100hz crossover.

As a quick test I shoved a rolled up pair of socks into each port and that calmed it down a good deal without much of a volume/sound impact. As shoving socks into speakers is not very professional what material would you recommend to lightly stuff the 2x2" ports?

Stuffing socks into the ports slows the air but changes the Q. You might want to cut your losses and get one really good sub instead of two of these. Otherwise, model the cabinet/driver and find out what size port(s) will be better.

Competition based on price doesn't yield great results. If you have to work that way, it's time to learn to counter a customer's objections with facts and maybe a listening test, so you can show them what the differences would be.

 

[annunaki]

Good points sir!

Sometimes it is more important to find the real objection. Perhaps you simply have not shown enough value in what you offer and lowered the risk enough that entices a customer to purchase (select your bid).

As has been suggested prior, increasing your knowledge base as well as recognizing customer hot buttons and objections goes a long way in getting sales so long as your price is competitive.

Stuffing socks into the ports slows the air but changes the Q. You might want to cut your losses and get one really good sub instead of two of these. Otherwise, model the cabinet/driver and find out what size port(s) will be better.

Competition based on price doesn't yield great results. If you have to work that way, it's time to learn to counter a customer's objections with facts and maybe a listening test, so you can show them what the differences would be.