| thecanuck |
Can anyone tell me off the top of their head how big the sub is? I'm not an audiophile and don't know whether to measure the outside diameter or inside diameter to get the industry standard for its size. Unlike many others, I actually LIKE the Bose system and the fullness of the bass. I've been told, however, that the best minimum size to have is a 10".
We want to replace the sub in our Frontier (get rid of the "fake" Rockford Fosgate) and put in a Phoenix Gold sub. |
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| Sw1tched |
| I believe it's a 10" sub stock. I know now I have 2 12" Alpine Type Rs so bass isn't a problem :D :D |
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| GMTURBO43 |
| Well, if you've ever gone to a home audio store and seen the cutout/plexiglass disply of the Bose Sub - it is a multi-woofer/multi chamber design. It is very small in perspective to the size most of us will compare it to. I'd guess maybe a 6"-7" woofer in the home sub. I can't imagine the one in ours is much bigger considering where it is mounted. It isn't big around and it isn't very deep. |
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| hfelknor |
Well the home system box is not a subwoofer.
The crossover is way too high.
It really is just a woofer or mid bass.
I run one of these systems in my home .
Like most small woofers, placement is critical.
I have mine in a Corner. That's where max bass is
developed.
As to the Murano. I don't know.
I know that if you want more bass, you can start by not piling stuff on top of the Sub blocking it.
In my Murano, I have a layer of pressed wood, a "Tool" layer, a "Floor" layer and a rubberized Cargo layer.
It's a wonder any sound makes it past all that blockage.
Homer |
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| Dookie |
| I think the sub is a 6 3/4" DVC "sub". I would actually call it a mid-woofer simply because of it's size. If you look on the top panel of the Bose sub in the spare wheel, you will see six or so nuts. Take those off and you'll see the sub. |
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| dk4500 |
| I have my bass control set in the middle and notice that the bass vibrates from the rear floor area where the sub woofer is located up to the front floor area and I feel the vibration on the gas and brake pedal and floor area...very annoying. I have an Acura that also has a Bose nd sub-woofer on the rear shelf but is so well insulated that you never feel any vibration. Nissan dealer says he can add insulation in the spare tire well, but I have my doubts about the result...any thoughts? |
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| GMTURBO43 |
I have thoughts...
The sub is bolted to the spare tire. The spare tire is bolted to the floor. The sub vibrates the tire - the tire vibrates the floor. I can't imagine there is much you can do to avoid this unless you were to isolate the sub from the tire somehow. Low frequency vibrations are going to happen. I have the bass set almost flat - might be on 1 - just because it does get too boomy when turned up. |
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| EdMPT |
| I just took apart the bose sub woofer because I was thinking about replacing the speaker. I noticed there were four leads coming from the speaker to the wiring harness. Does anyone know why there are four instead the usual two? |
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| Dookie |
The sub most likely has whats called a dual voice coil. It is common in the audio industry to extract more power from amps. The lower the impedance=more power going to sub.
1 DVC driver with Voice Coils in Series
Connecting the two voice coils of the driver in series (+ to -) will result in the following impedances:
Dual-6 Ohm Subwoofer: 12 Ohms
Dual-4 Ohm Subwoofer: 8 Ohms
Dual-2 Ohm Subwoofer: 4 Ohms
1 DVC driver with Voice Coils in Parallel
Connecting the two voice coils of the driver in parallel (+ to +, - to -) will result in the following impedances:
Dual-6 Ohm Subwoofer: 3 Ohms
Dual-4 Ohm Subwoofer: 2 Ohms
Dual-2 Ohm Subwoofer: 1 Ohms
If you measure both sets of +/- terminals on the sub, usually the ohms reading on the multimeter is a little lower than what the actual impedance of the sub is.
Parallel: |
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| EdMPT |
| So basically it's just a jumper for an added terminal on the opposite side of the magnet? Is that where the extra power comes from, just less resistance across the magnet? |
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| Dookie |
| I dont think it has anything to do with the magnet, though I could be wrong. I do know that the magnet controls the voice coil movement though. It's the actual voice coil that has different windings in it that created the impedance of the subwoofer. |
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| Dave N |
FWIW
The Bose subwoofer size is 5.25". |
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| EdMPT |
| I am surprised the sound that comes from it considering it's size, but I would still like to replace it. Does anyone know if it's possible to use the existing harness and wire up a different sub, or would I have to go with adding an amp in the back along with a new sub... My main concern is quality of sound. I don't need anything obnoxious or too loud, I just like to have a deep clean bass from my stereo. |
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| jaak |
| I would expect it's got two windings because it's a cheap way of combining left and right into one speaker. |
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| EdMPT |
| awwww, that makes sense...and maybe a lot easier for replacement |
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| thecanuck |
quote:
Originally posted by Dave N
FWIW
The Bose subwoofer size is 5.25".
Thanx mucho Dave. |
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| Dave N |
quote:
Originally posted by EdMPT
I am surprised the sound that comes from it considering it's size, but I would still like to replace it. Does anyone know if it's possible to use the existing harness and wire up a different sub, or would I have to go with adding an amp in the back along with a new sub... My main concern is quality of sound. I don't need anything obnoxious or too loud, I just like to have a deep clean bass from my stereo.
The amp is custom-tuned for the frequency response characteristics of the Bose speaker that is in that bass box. More than likely, if you swap to a different speaker it will sound worse, plus there's a risk that damage to the amp and/or speaker could occur. If you're really wanting to change out components, your best bet is to go with a complete aftermarket set up so that the components can be properly matched up.
I hope that helps.
Dave N |
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| Dave N |
quote:
Originally posted by thecanuck
Thanx mucho Dave.
No problemo. If you need anything else, don't hesitate to ask. |
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| Labotomi |
quote:
Originally posted by jaak
I would expect it's got two windings because it's a cheap way of combining left and right into one speaker.
This is wrong!!!
The signals to each voice coil must match each other. If you were to wire the left signal to one and the right signal to another, any time the signals were differen't the voice coils would be trying to move independently of one another. Since they are connected to the same cone, it couldn't move accurately.
Many manufacturers make dual voice coil subwoofers. It's done mostly to give people more possibilities when wiring, therefore matching the impedance of the system to the optimal performance range for the amplifier. |
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| jaak |
You can think it's wrong, but I still believe it. The speaker will move unless the audio is out of phase on the two channels. Bass is rarely out of phase, as it's sheer stupidity to build a stereo track like that, as it creates a situation where your amplifiers are working hard to produce energy that will just get cancelled out, accoustically. The two voice coil windings are on the same carrier, so audio energy from either channel will deflect the cone.
Selectable impedance is desirable on aftermarket speakers, but not on OEM speakers, they're buying in quantity, so this would be an additional cost, for something that would just be engineered, not tried later. So there is no benefit to Nissan to do this, and it would cost them more to do it for that purpose.
Since it's likely someone will think I'm full of it, I'll make it easy for you to see what Nissan's done...
Here's an excerpt from the Service Manual. :D |
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| clane47 |
There are other reasons for having two windings on one voice coil. I helped build some woofers for Infinity's first Quantum Line Source speaker system back in the mid 1970's. The purpose of the dual coil was to get around Hoffman's Iron Law. This law essentially states that as a speaker approaches resonance, its impedance goes up. This makes it harder to deliver power to the speaker. We fed full signal to one coil, and the 2nd coil was fed through a filter such that it began to get signal as the speaker approached resonance thus keeping the impedance flat. It worked very well! I'm not suggesting that Bose is doing that on the woofer system in the Murano, I'm sure they aren't. Just more food for thought. :D
Regards,
Chuck Lane |
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| Labotomi |
Do you know if there is only one signal coming from the headunit?
You're right about low frequencys being recorded in mono. Since this is the case, why would they need to combine the left and right channels? It would be easier (and cheaper) to produce a single channel amplifier and single voice coil subwoofer? Other car manufacturers have used single channel setups for their subwoofers.
Clane47, I may be misunderstanding what you're saying, but If you're talking about resonance as in resonant frequency then the impedance should go up as you get farther from resonance. I guess you'd apply power to the second coil through a circuit that has a different resonant frequency. |
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| clane47 |
Labotomi,
Hoffman (the H in KLH) actually states (in part): The efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce). However, one of the effects of this is that as a woofer approaches its own fundamental resonance (cutoff), impedance rises dramatically. The company I worked with at the time, Watkins Engineering, held a patent on this particular use of a dual voice coil. We licensed Infinity to use the system. Of course, another use of the second coil is to generate negative feedback to the amplifier. A couple of Japanese companies used this as a matter of fact.
Regards,
Chuck Lane |
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| jaak |
| I agree, there's other reasons to do this, but automotive OEM sound is all about making it sound OK (not fabulous) at the lowest cost possible, so I would really be surprised if it's anything more than just being a cheap way to put both audio channels into one woofer. |
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| clane47 |
jaak,
I agree completely. I'd be flabbergasted to discover that they'd done anything except the cheapest thing possible. :p
Regards,
Chuck Lane |
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| Dave N |
For this system the amp has 6 channels, of which, two are bridged for the subwoofer. The DVC is set-up in parallel to get the lowest impedance (and - obviously - the most power to the speaker). This eliminates the need for a slave amp to drive the subwoofer in the enclosure (hence, less cost). It's not a bad balance between cost and sound quality.
Sure, a custom designed aftermarket system can be made to sound much better but at the trade-off of cost and, in certain cases passenger space (you gotta mount those monster 12" subs somehow:4: ) |
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| Tyler_Canada |
No, those won't work. By "free air", what they are actually saying is "really, really large enclosure": the trunk of a car. You mount them on the rear deck above the rear seats, and the entire trunk becomes the enclosure. All subs have to have the front sealed from the rear, except by ports (as in ported or bandpass enclosures).
If you want lots of bass AND/OR low frequency extension in a small space, the best idea is large excursion subwoofers. An 8 inch sub with a 1 way XMax (excursion) of greater than 1/2" in a sealed enclosure would sound much, much better than stock, and not take up too much room. |
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| simplesb |
| Exactly Tyler, I was thinking of this before when when I had an older Eclipse. The rest of the car would be somewhat sealed off from the trunk. I could just mount up subs on that cover thingy for the trunk, maybe reinforce it. The problem with Free Air subs is the amount of space you have. You have would want subs that would best utilize the amount of space that you have. Having the entire car as the area like the Mo probably wouldn't be efficient. If I remember right, Free air subs were made for making your trunk a enclosure. |
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| Tyler_Canada |
| Inefficient is an understatement. Due to the distances (depth of sub) and frequencies involved, the sound waves from the front and back of the subwoofer would be out of phase, causing destructive interference (sound cancellation). There will be almost no sound. Using the cargo cover would be useless too, because it won't block sound in the bass frequencies. Now you could use the "free air" subs mounted in the spare tire cover. Then just place a sheet of plywood or plexiglass over the sub when you need your trunk. |
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| GripperDon |
| The two sets of connections do a nice thing. THey are from each channel and therfor IF THEY ARE IN PHASE the subwoffer moves if OUT OF PHASE the sub does not move. ergo automatic enforcement of low frequencies which are of long wave length and usuall arrice at recording mics in phase beacuse of this. It also let the sub get twice the energy to drive it at appropiate frequencies without added amplification which would be false as compared to what we would hear. |
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