Building a Quatro 15 sub, few questions (1 Viewer)

[AndrewLevine]

After getting a lot of help from you guys in picking out my system (HK AVR235 + Athena F2.2s) I decided I wanted to try DIY for a sub. Most people said to use a PE Quatro 15" and PE 240 watt plate amp. It is for 90% music (classic rock) in a medium room. My questions are:

-for an extra $20, is the 300 watt Bash amp worth it? (it has more power and a dedicated LFE input vs having stereo inputs, not sure if that matters) and if it is worth it, would i have to build a little cover to protect the innards because there is no backing?

-because the Q15 is not shielded, how far must i keep it from other electronic devices?

-(last, and possibly stupidest question) If I line the inside of the sub box with tin foil (between the wallls and foam) would this cut down on the distance the sub may be placed from electronics?

Thanks for your help,
AL

 

[Tab Nichols]

Foil will make no difference as it is the actual magnetic field off the magnet causeing the problem. You can get a second magnet to cancel the magnetic field, but they can be as expensive as if you just bought a more expensive sub. Just keep it away from your tv.

 

[Brent_S]

Power handling depends on your alignment. You didn't say if you were going ported or sealed, so I modeled examples of both.

In a 6 ft^3 tuned to 20hz, the Q15 is Xmax limted to less than 300 watts between 25-40hz, with the min Pmax being 230 watts @ 31hz. 300 watts in that range will delver 11.5 mm excursion, which is *probably* safe...don't know the actual Xsus of the Q15. SPL difference between 240 and 300 watts is about 1db.

The classic 3 ft^3 sealed alignment is Xmax limited to less than 300 watts below 38hz. It's still a good match for the 240 b/c even if you could give it the full 240 at 20hz (stock rumble filter won't let you), excursion is only 11mm, which exceeds Xmax by a hair, but shouldn't actually bottom the driver. SPL difference is still around 1db...remember, you need to double the power to achieve a 3db increase, all else being equal.

Both amps should be fine, but you really don't benefit much from the extra $$$ spent for the BASH.

As Tab said, your video display is the only thing that should be effected by the Q15's magnetic field. CRTs are the most sensitive, but distance still varies by model. I would think LCD/DLP/Plasma would be unaffected since they're not electron gun based.

 

[AndrewLevine]

I like the numbers and the prices, however as much as I want to build a 15" Quatro, I'm beginning to wonder if it will require too large of a box for my tastes. Are there any drivers that would yield similar musical results for around the same cost?

Thanks,
AL

 

[Ryan Schnacke]

The Quatro 15 is a pretty darn good value. To get similar performance in a smaller box, you'll probably have to go with a higher excursion 12 inch woofer. It would be very hard to find this for the same price as the Quatro. Here's my suggestion:

Look at the 12" Assassin woofer from www.ascendantaudio.com

It displaces 1.488 Liters of air and costs $90 (the $75 intro price has expired). Compare that to the Quatro which displaces 1.628 Liters for $86 (on sale right now for $75). So its a little more expensive on the bang-for-the-buck scale, but still in the same ballpark. This is actually a very good deal compared to the Dayton DVC woofers and the old Adire Shiva's which were and are still considered good values.

 

[Tab Nichols]

I agree, assassin or adire shiva would be your best bets if smaller is the way to go...