Driver Replacement for Yamaha Subwoofer

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I purchased four Yamaha YST-SW315 subwoofers from a home builder that was using them as models in home theater setups in their houses. They did not cost me much and were essentially never used. They do look nice and they have a 1 cubic foot box size with a 3" diameter by 5" length flared port. The SW315 has a 10" downfiring woofer.

I bought them to try multiple small subwoofers to reduce room modes (which worked well). These subwoofers obviously do not go low. I like the fact that they have forward facing controls. I used them with an antimode device but there emphasis is above 40hz.

My question is could anyone suggest a replacement driver that would work in this small of a cabinet that would go lower? Otherwise I would likely not use these long term or will sell them. I see the limitation of the sw315 box size being an issue as commercial subs with 10" drivers appear to have output around 20hz but about double the size. I just wanted to ask before looking at something else. I want to thank you for any input you may provide.

The specs are as follows:
YAMAHA 10" SUBWOOFER 270 WATT AMP. Frequency Response : 20 - 160 Hz (-10 dB)
Yamaha YST-SW315 Subwoofer System - Black Ash
10-inch driver with high-efficiency, 250-watt PWM digital amplifier
Advanced YST ensures that the speaker and amplifier work together to create perfectly linear speaker motion
BASS (Bass Action Selector Switch) tailors the sub's output for video or music at the touch of a switch
Yamaha's QD-Bass technology radiates bass in all directions for greater impact. Frequency Response : 20 - 160 Hz (-10 dB)
 
My question is could anyone suggest a replacement driver that would work in this small of a cabinet that would go lower?
The box is tuned (Fb) to around 52 Hz, regardless of the speaker used.
In general, response drops at 24 dB per octave below Fb for "standard" box tunings, which have adequate box size and Fb around Fs.

Probably better to sell the cabinets "as is" and design for what you want, rather than swapping speakers in to a too-small box that will require a longer port which will reduce box size even more.
 

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ParadiseComm / Weltersys,

I agree with both of you. ParadiseComm thank your for the suggestion but I likely won't get much improvement per Weltersys simulation with a new driver. I will use them as they are or sell them. Weltersys thank you for the simulation it really points out to me the limitation of the box size. I guess there is no free lunch.

Best Regards,
gwho
 
The box is tuned (Fb) to around 52 Hz, regardless of the speaker used.

52 Hz sounds pretty high for a 10" subwoofer.

Yamaha's info on the subwoofer suggests that it's 10dB down at 20 Hz. If Fb is 52 Hz, I think that the response at 20 Hz will be much more than 10dB down.

Of course, it's always possible that the specifications aren't all that believable, but I'd be tempted to run an impedance/phase test of the driver in the enclosure to see where Fb really is.
 
Thank you for all the thoughts on the subwoofer. I will definitely try plugging the ports and see how they sound. Perhaps I will get more low frequency output using for of them.

Regards,
gwho

If this subwoofer uses some sort of feedback loop to modify its output, plugging the ports is likely not going to produce good results.

I must do some more reading about this YST tech. Looks interesting...
 
Karl Erik Stahl developed a technique where the amplifier is synthesizing some of the parameters of the driver used, most impotantly the moving mass AND the resistance of the voice-coil. With a negative output-impedance of the amplifier the eletrical Q of the driver is reduced, and the synthezised mass-increase is lowering the Fs without decreasing the efficiency.
The bottom line is that even with a new driver the amp will dominate the driver-parameters, which means that a new driver probably not will improve the performance, even if the circuit is calibrated to fit the new driver the best possible way.

Steen
 
Thank you all for the discussion, information, and thoughts. Merry Christmas and Happy Holidays to all. As I previously mentioned, I will use the Yamaha's as is or sell them. They do not sound bad at all when using four of them in a small room but they do not have the low frequency impact of larger subwoofers that I have heard.

Regards,
gwho
 
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