Sorry brothers christmas rush and the holiday season plus new tax problems and worst of all a dropping market and i have the recipe for no car work. Not to mention i screwed up opening the center speaker... Just like chris the new speakers are just looking at me waitnint to be installed. Im sure i will get them on but not in the near future. I more on finding an eq for the iphone amp to adjust the sound comin out of the system i have.

 

I've been thinking about the Bose sub quite a bit and ways to improve it and am thinking of a possibility. Right now, there is a big peak at 50Hz due, I believe, to the port frequency combined with the rolloff of the sub xover. I am guessing that the port is tuned to about 50Hz and that the rolloff is second order around 80Hz. This leaves very little sub response - just a big hump at 50-70Hz. There is no way (basic physics) to extend the response of that sub enclosure combo below the port freq.

However, if I am correct, and the port freq is about 50Hz and it is a simple ported enclosure (which it appears to be - contrary to the bandpass descriptions I have seen online), if one were to plug the port, essentially created a sealed enclosure with the same amp, the output level of the sub will decrease, but there will be a more gradual rolloff down below 50Hz and actual response in that range.

In order to then properly use this additional bass extension, one will have to insert in line with the signal going to the sub some form of processor - perhaps a small parametric EQ which will allow level control and tuning.

Does anyone know the specific connector used for the sub so I can fabricate a small harness and tap in without cutting wires?

Of course, the end result will be better bass, but with much more significant limits on power/output level.

One has to wonder if one could then replace the drivers and amp in the enclosure with others for a better result. Once tuned, the processor could go in the enclosure as well.

Anyone have a spare 997 sub box (drivers or amp not needed) to donate to the cause or otherwise sell at a favorable price?

db

 

Hmmm that seems like a logical thought. But if we were going to seal the thing would you need to destroy whatever baffle that is there inside the box that previously worked with the supposed band pass design?

 

Good point if it were a band pass design, and I have not taken it apart myself, but from the internal images one can find around the forums (look up the stuffing threads), it appears to be a simple ported enclosure. Moreover, if it were a bandpass design, the woofers would not be downfiring and open to the cabin as they are.

I won't have time to try this for awhile, but next step is to (1) seal the ports and measure the differential response, and (2) then examine the input signals with a scope to see what information about the signal levels, etc can be gained in order to ultimately interpose some form of EQ and level control.

I am still concerned about quickly running out of sub output/headroom on the system with this approach.

db

 

Check out my pics of the sub here. You're right, it is a simple ported unit, I believe. Plugging the ports would be pretty simple as they face the cabin, but not sure what to use to do it. After you plug the ports though, the woofers fire downward, there will be a huge loss in output.

 

Oh tons of subs are on eBay. Some have stupid prices, not sure why anyone would but one as an "upgrade"! Should be cheap to get one. The connector is a custom molex or whatever.
Adding an eq is a nice thought, but it sounds challenging. The sub enclosure is tight; in not sure even a 6" set of speakers would fit.

 

The loss would likely be 3-6db depending on the tuning of the enclosure and the parameters of the driver. I will measure it. Downward firing has little impact on the low frequencies in terms of propagation and will not in and of itself cause a material loss in output. The loss is a simple artifact of the enclosure type as it interacts with the driver characteristics.

db

 

I'll ask the stupid question since I was thinking about it:

What do you think will happen if the the woofers were to face "up". Basically, cut the appropriate holes and remount the speakers facing the inside roof?

Also, seal the ports. From what I understand, small enclosures benefit from sealed design.

 

You know I have an aftermarket box that fires up with either 2 6 in JL W3 or 3 6 inch W3 that fires up and fits in the same foot print. I ca also put the factory connector on the box and it has a Rockford 500x1 amp that power it and I have quite a few OEM connectors lying around. All you would need to do is run power and ground.

 

How about using 2 of these in the Bose sub box:

http://www.parts-express.com/peerles...ofer--264-1074

 

Starting my install tomorrow


Ryem, did you use 3/4" spacers on the 8" part? From your pics it looks like 1/2" (and that would be ideal for me).

 

I used 3/4 on the 8's.

Did you read the whole thread? Are you using the Focals? If you do, read the whole thread. There were some tips and tricks to the install.... and don't wreck your dash openings.... use my tip (it would save your dash and hours of install).

Good luck!

 

Oh year, I have read the whole thing multiple times and I knew that you had used 3/4". Yes, using the same Focals that Ryem has.


The reason I was asking is that he didn't specify the spacer size and it just didn't look quite as thick. Also, the Del Ray guy mentioned that with a different brand a 1/2" spacer worked and that one is deeper than the Focal.


The shop I am going to have make the spacer has 1/2" material (not MDF) that is more suited to door parts. Not that I think MDF is bad, however.

 

I would guess that less than 3/4" works as there appears to be quite decent space in the door for the magnet. I only note that MDR provided my spacers and AFAIK "3/4" MDF may not be exactly 3/4", but that's how it is sold. Note that if you use less than 3/4", you will create a gap to the interior door panel. The Bose woofer actually has a seal to the door panel, which is a benefit. Best to go as close to the door panel as possible, without having any interference.

 

Ok, I am not done yet, but about 1/2 way there! I got some brackets made by my local audio shop. The front woofers hooked right up, I even reused the OEM connections, so no cutting or re-wiring! For the other door location and the rear, I took the advice of my installer and stripped the wire partially and soldered a connection to the new speaker, so there too, I could return to stock easily.


Have to complete things before I make any detailed feedback, but I am shocked at how louder (more efficient?) the Bose speakers are. Interesting. Of course, as someone who cares about the sound and not the loudness, I know this doesn't mean anything in an of itself. Can't wait to get it all together (plan is tomorrow after church) to finally hear it.


Thanks all for the tips/tricks! I followed this thread with no issues! The tip about the OEM wiring and the woofer is my only "find" so far. Wish the others were like that.


Chris