[t-dog]

I have a pair of sandbox sealed subs I built last year. They are 3cu. Ft and have SA-1 amps in them. Drivers are MFW-15's and they are both blown. I'm not sure why this happened and Danny thinks that clipping might have been occurring. Regardless I need to replace them and ideally I want to reuse the boxes and amps. I sent a PM to Mark Seaton at Danny's request since he thinks he might actually have MFW-15's. If I can't get a few replacement MFW-15's I'll need a backup plan. Any thoughts?

Thanks in advance.

[mojave]

The Dayton DVC385-88 or RSS390HO-4 will work well, but the second one will have a lower Q in your box size and is probably the best option. I recently put the RSS930HO in an MFW-15 cabinet and powered it with a 1000 watt Dayton SA1000 amp. It sounds very good.

I would recommend using the line inputs or speaker inputs on the amp so that the shaping circuit is in effect (it is bypassed with the LFE input). That will help the sub play deeper and you have plenty of excursion on these drivers with only having 200 watts.

I have 6 of the MFW-15 drivers in three dual opposed cabinets. I have a fourth cabinet and recently sold its two drivers. I might be willing to sell two more drivers. I am working on another sub project anyway and am only currently using 4 of the drivers in my living room.

[t-dog]

Mojave,

Thanks for the recommendations. I will probably get the RSS39OHO-4 you recommend unless someone can suggest something more appropriate for my boxes. I do have a few questions if you don't mind answering. Knowing that I use the SA-1 amp for my enclosures, am I going to run into a sub optimal situation where the power is lackin themg to sufficiently run this driver? You mention you run the Dayton SA1000 amp which is 5x the power of the SA-1. The enclosures I have are sealed, should I port them with this new driver? If so does anyone have a spec for the port I should use? I would be limited on dimensions since the box is essentially a 18"^3 internal.

You mention possibly selling 2 of your MFW-15's which I might be interested in but if the Dayton is a much better driver I think I will go that direction since I don't want to find myself in the same situation I'm in now.

As for the line inputs or speaker inputs I currently use the line input. Danny told me to use this and not the LFE input for the reason you mentioned.


Thanks for your help so far. I really appreciate it.

Sometimes I wish I would have just went with an IB setup but I was too afraid to have of having the cops come over every time I played a movie. I can hear the subs outside already. I can only imagine moving that much air in my attic and how that would sound 10 houses away......

 

[sandbagger]

Mark and I have a plan and a good sample driver for a replacement for the MFW-15's with a bit of added performance.
Problem is the quad15 never really took off and there just hasnt been enough interest or demand for the new driver to warent a production run as these are not off the shelf.

[mojave]

The RSS39OHO-4 driver will work in a sealed sub down to 1.5 cubic ft. With a larger box it takes less power to drive the sub so you are fine with 200 watts even though the driver can handle more. With the gain circuit on the amp, you might even get close to full excursion on the low frequencies when using 200 watts. For each 3 dB increase in output it requires a doubling of power. You you had 800 watts per driver this would give you 6 more dB of headroom. However, it is probably loud enough for most of your listening so it really isn't an issue to "only" have 200 watts.

You could add two 3" ports that are 18" long and your box would be tuned to 25 Hz. If you used the LFE input you would bypass the gain circuit that isn't needed with a ported sub. You can use a more powerful amp with that box size and get more output, but if you are keeping the same amp I would just stay sealed. Sealed is easier, anyway.

Problem is the quad15 never really took off

I think the problem is that the Quad15 modded amp and cabinet weren't ready until after all the extra MFW-15 drivers had sold out and DIY guys were already making their own boxes and using other amps. The modded amp works brilliantly and does an amazing job with 4 of the MFW-15 drivers. The system I had at the KC GTG cost me under $1000 if I factor in the price of the modded amp yet sounded very good up against sub pairs costing 2-4x its price.

[t-dog]

Thanks for all the great responses. I do have one additional question. Since this issue arose with these subs it made me reflect on some of the gear I might have lying around. I remembered I had a Parts Dxpress Bash 500 plate amp that I never did anything with. Im wondering if I could utilize it and make an additional sub for the theater room using this amp and a suggested woofer(s). Having a 3rd sub is a good or bad idea? I have a large stage and I could fit almost any size enclosure on it between the other 2 subs. I'm just thinking it might take a load off the 2 15's having another sub in the mix. I don't know if this creates any strange harmonics though so I'm looking for thoughts/recommendations. My only restriction in dimension is 19" total enclosure height.

Thanks!

[mojave]

I would just build another 3 cubic ft sealed subwoofer and put the same driver in it as the others. If you gain match all three subs (hold the SPL meter right in front of the sub instead of using the listening position) you should be fine. The new sub might have a different rolloff on the very bottom end because the BASH amp doesn't have the gain circuit in it. You can modify the bass boost on the BASH amp by replacing resistors if you follow the boost table at Parts Express.

[t-dog]

Thanks for the reply. How does one determine the correct resistors to use? Is it a function of testing them with an SPL meter as you suggest or is that solely to adjust the gains to make sure it's equal across all subs? Or is it something that can be predetermined based on box size, type and speaker. Then using that, comparing it to the SA-1 and figuring what works best to make them as equal as possible? I apologize in advance if this is a silly question. Thanks in advance.

[freerider]

I apologize for going off topic, but another option is to buy Turbo MFWs off a guy who bought them from mojave.     I just took ownership last night.

[freerider]

**oops, double posted**