stealth panel and sound limitation?

Well, it was done by HiFi Buys and I have always been very happy with the custom work they have done on my cars. They seem to be very knowledgeable and very nice all of the time. Many times (back in the days) when I tried to dabble in my own installs, I would either go up to HiFi Buys or call them and the install guys would sometimes go out of their way to help me figure out what I did wrong without me even paying them... However, I went to a different shop this time because I moved away from the normal Hifi Buys location I used to go to. Anyway, he said he'll cut some holes in the thing and mount the grill's on the panel. I assume I should be able to convince him to remove the 1" gap between the box and the panel and drill the panel directly to the box and then insert the subs through the panel into the box so that it gives a look as if the subs were built into the back wall of the trunk. That's what I really wanted all along...

What I think is happening is that the distance between the subs and the back of the trunk is allowing the sound waves to come back and cause constructive interference with the sound coming from the back of the subs into the passenger compartment. It may have worked out just right in your case...if the box were built slightly differently, you might have had destructive interference where the sound waves would have been cancelling each other out causing less bass. A lot of times it is best to avoid those possibilities when designing the system...it is always nice when the box, tuning, and car all come together to allow for everything to hit your ear just right!The Flakman

I feel strange. I have deja vu and amnesia at the same time.

John | Manteca, CA

Flakman wrote: What I think is happening is that the distance between the subs and the back of the trunk is allowing the sound waves to come back and cause constructive interference with the sound coming from the back of the subs into the passenger compartment. It may have worked out just right in your case...if the box were built slightly differently, you might have had destructive interference where the sound waves would have been cancelling each other out causing less bass. A lot of times it is best to avoid those possibilities when designing the system...it is always nice when the box, tuning, and car all come together to allow for everything to hit your ear just right!

Uhm..... no. 

In this case, sound "bouncing" off the back trunk wall would have better response. It's not as complex as you are making it sound.

With the panel in place, you have a dual sealed chamber bandpass box . (Sealed rear chamber, semi-sealed small front chamber)

In other words, you have a bandpass box  with no way for sound to vent out of it.

The box designer just didn't have a clue (or materials) to correctly execute what he had in mind, and didn't bother to PAY CLOSE ATTENTION to what the owner originally wanted. (According to teh picture posted.)

[quote]With the panel in place, you have a dual sealed chamber bandpass box . (Sealed rear chamber, semi-sealed small front chamber) In other words, you have a bandpass box with no way for sound to vent out of it. [/quote] That's exactly what I thought as well. I mean, the panel is literally pressed up against the speakers with very very little room to breathe. While the panel is about 1" off of the speaker box, the subs mounting hardware is about 3/4" - 1" thick... So, the panel is pretty much pressed up against the mounting hardware for the subs. They said they'll fix it up on Thursday. My question is, will this damage the subs at all while playing them? I would assume not, but I'm not so sure...

intargc wrote: [quote]With the panel in place, you have a dual sealed chamber bandpass box . (Sealed rear chamber, semi-sealed small front chamber) In other words, you have a bandpass box with no way for sound to vent out of it.

That's exactly what I thought as well. I mean, the panel is literally pressed up against the speakers with very very little room to breathe. While the panel is about 1" off of the speaker box, the subs mounting hardware is about 3/4" - 1" thick... So, the panel is pretty much pressed up against the mounting hardware for the subs. They said they'll fix it up on Thursday. My question is, will this damage the subs at all while playing them? I would assume not, but I'm not so sure... [/QUOTE]

If  the panel is too close to the speaker, you run a chance of the surround rubbing up against the backside of the panel. If you see a white-ish ring along the top of your subs surround, it was touching the backside of the panel.

In most severe cases, the surround is extremely weakend, worn through and likely tears.

Ok, so here is the outcome... I took them the panel yesterday. I slid my hand in between the panel and the box and felt around for the speaker. There was no space between the speaker and the wall at all. You could MAYBE slide a piece of paper between the two with some wiggle room. However, I couldn't even get my pinky finger between the panel and the speaker (I have skinny fingers too!). In other words, I'm sure when I had the system turned up loud, the subs surround or speaker had to be hitting that wall a bit. So, what they did was cut out a large rectangle section on the panel. He then put a metal mesh grill in that rectangle area and covered it with carpet so you can't see the hole or mesh grill. However, this leaves maybe 1/4" between the speaker and the mesh part of the panel now. Is that enough room? I can slide my middle finger in between the two now. I'm just worried as I don't know how far the speaker pushes out during high volume and very low bass. I know for a fact the speakers were hitting the panel before. You could hear a sort of slappy sound during high volumes (in which I quickly turned it down). I don't hear this really anymore. But, I'm still worried. Should I adjust where that panel sits? What I can do is get thicker pieces of wood that attach to the box. There are 3 1" thick pieces of wood that attach to the box and then the panel attaches to those. I can maybe get 1.5" blocks of wood at home depot or something. That is, if you guys think it would be a good idea... If you think I'm safe now, please let me know...

2 JL Audio 12W3v3 Subs. I looked at the subs when he took the panel off and I didn't see any marks or anything. However, I didn't get close up on them and look either. Yes, I voiced my concerns and of course they weren't very receptive to what I said since I'm not well educated on all of this. I just kept hearing over and over "I just don't see how this panel blocked any sound..." And, yet, they wouldn't test it with and without the panel to see my point... But like 3 guys said the "I can't believe..." line and even stuff along the lines of "We've done that setup before and it didn't block out any sound" or "It sounded good to me before you left". So, I just said "Hey, maybe I just somehow mysteriously tricked myself into thinking it was better sounding. However, I've managed to trick myself and I would like it fixed regardless."