First Home DIY Subwoofer - questions (1 Viewer)

[TonyiBe]

Ryan,

I can almost guarantee the AV15 can take the 720 watts. I have an AV12 with the Rhytmik at 380 watts and the gain is all the way up. The AV12 takes it like nothing and NEVER bottimg out. Now i have 2 JL audio 12W3D4's in my car with 1400 watts to them with NO Problems. Comparing the TC sounds AV12 to the JL audio in construction is no comparison. So 720 watts should be no problem. Better yet i have a QSC amp that puts out 750x2 and i will try it in the next coming days, but i am highly convinced it can take the watts as long as you don't over do it.

 

[Bob Huskison]

I've done some more searching and answered Q#1.

 

[Brian Bunge]

I'll let you all know how the AV15 handles the HS500 in a week or so. I'm building such a beast right now!

 

[Bob Huskison]

Excellent!

I'm on to the design phase - laying out dimensions, brace positions, etc.

 

[Pete Mazz]

I'll let you all know how the AV15 handles the HS500 in a week or so. I'm building such a beast right now!

Oh No! Brian's moving from blowing up Tumults to blowing up AV15s....

Pete

 

[Brian Bunge]

Pete,

At least the AV15 isn't mine!

 

[Bob Huskison]

I've read (on http://www.diysubwoofers.org) that the port needs to be at least one diameter from any external edge and at least one diameter away from the driver.

How critical is this?

Due to my footprint (internal dimensions - 17.5" W x 22.25" L) it doesn't look like I can achieve this. Is it more imporant to have distance from the driver or the side? Or is this more of a guideline?

Will there be performance issues if I can't achieve this?

Thanks.

 

[Owen Bartley]

Bob, the port for my Tempest had to be squeezed into the footprint and I haven't noticed any serious negative effects. (that doesn't mean that they don't exist). The one rule I tried to stick close to was to leave one port width of room between the end of the port and the top of the sub box. I had to cut it a little short, but I stayed close.

 

[Bob Huskison]

Owen,

Thanks for the info. I won't have any problem with the back of the port; so that is at least one rule I won't have violated. Additionally, the lack of posts to the contrary, it doesn't look like it is that big an issue. Good.

 

[Chris Tsutsui]

I would go with the AV15 + 500w tuned to 20-24hz for HT.

Perhaps use downfiring driver with dual downfiring flared ports.

With a higher tuning, the ports get shorter so they'll fit and you'll have a nice punch and presence that's perfect for home theater bass. You could also use plugs for ports to change the tuning and have a variable tuned subwoofer.

 

[Jonathan T]

In responce to the question about the power handling of the AV15, I e-mailed Stryke.

I asked:
On your site, it says the voice coils can handle up to 500 watts, but it takes about 720 watts in all but the largest enclosures to bottom out the driver. What do you have to say about this? Are you underrating the voice coils? Or is this their true maximum power handling?

Thank you
He responded:
Hi Jonathan,

The thermal power handling of 500W is a conservative rating. You should be just fine with power levels up to 1000W or so. However, you will be able to push the woofer to its full excursion with far less power than 720W in most enclosures. Most software models RMS excursion. You need to multiply by 1.44 to get the real exursion at each level. This applys to all woofers.

John

There you have it.

 

[Bob Huskison]

Thanks. That'll give me some additional information when it comes to setting the high pass filter.

 

[Nathan J]

You may want to check out www.betteraudio.com

The 12" sub will get you flat response down to almost 20hz in only a 2.5 cubic ft box. That sub is alot like a brahma( it uses XBL2 technology).

If you want to go a little lower with the tuning, make the box like 3cu. ft. tuned to 19.5 hz or 3.5 cubes to 19hz.

The only problem might be the port length, but you could always buy those flex ports from JL Audio. You will need a decent amp to push this sub, as it will take 1000 watts RMS no problem, although you dont NEED that much to get decent spl levels out of it. I have personally tested these subs, and they sound incredible.

 

[Ryan Schnacke]

"Most software models RMS excursion. You need to multiply by 1.44 to get the real exursion at each level."

WinISD pro alpha allows you to plot peak (real) excursion and is considered one of the more accurate of the freeware simulators. From what I'm seeing it would take about 800 watts to reach Xmax above tuning in even a large, low-tuned enclosure - 8 cu ft tuned to 18 Hz.

The usual response I get at this point is something like: Woofers with really strong motors like this will perform closer to ideal ... or perform better than the sims indicate ... or something like that. But if the discontinuity is really this big then we need to fix the model or the equations or something. Because they seem to work pretty darn well for the Shiva/Tempest/DVC and others.

I recall at least one guy saying he had to crank the amp gain to get similar volume from his AV12 as his previous woofer. So there's a couple of reasons to believe the AV's are power hungry.

 

[David Lorenzo]

Win ISD Pro seems very accurate as far as I can tell. When people talk about bottoming their subs I always plug in the numbers to see if the bottoming they're talking about shows up in sims. It almost always does.

For example. People talk about bottoming their Tempests with X amount of power and when modeled it shows that with X amount of power the Tempest would run out of excursion at X frequency. It usually correlates to the frequency that the person was trying to play at loud levels.

My 2 cents.

 

[Bob Huskison]

Another question as I finalize the last dimensions and design.

The other enclosures I built were for car audio, so I've not used plate amps before. Do I need to account for the size of the power supply separately in my volume calculations?

For example, the cutout size of the HS500 is given as 6 x 13.25 x 4, while the power supply is 7.5 x 13 x 3. Is that 7" of depth or 4"?

Thanks.

 

[Ryan Schnacke]

I'd just figure somewhere around 3-5 liters for that plate amp and call it close enough.

 

[Bob Huskison]

This preorder on the AV15 is killing me. I'm not sure I'm up to waiting that long. I'm thinking about changing to the HE15. The $ is no big deal. Although I could go with a smaller box, I'm still thinking of keeping it in a 4 ft^3 vented box.

Since its Re is 6 Ohms, I'm concerned about running the HS500 at 3 Ohms. Any comments?

 

[Peter Jessee]

I'm sure you bass-mad pro-amp owners will tut-tut such a weak-kneed suggestion, but how about a Dayton 15" DVC in a sealed 4 cu ft box, with a Rythmik 380 watt or HS500 amp? I'm helping my cousin build one right now with the Rythmik amp.

I personally like the accuracy of a sealed design, and my old Rava would rumble my 4500 cu ft living/dining/kitchen area quite nicely. The DVC/Rythmik combo plays about 5 dB louder, with similar Q and extension. There's no concern about port noise, overexcursion below tuning, fitting a long port in, or ever frying anything - everything works within it's limits. There's no port or PR to deal with, just a tight sealed box and a bottom firing driver putting out 118 dB of bass. All this for a combined amp/driver price of under $300 delivered.

Just a thought.

Peter

 

[Joey_R]

I’ve got some questions for the pro amp crowd:

1.Do you guys have to use any kind of a rumble filter for your vented enclosures? If so, how are you doing it?
2.If I have a 20Hz vented tune, how important is rumble filter in HT applications? Rock music applications?
3.Are any of you having problems driving the pro-amp sufficiently? If you are, what are you using to increase gain to the pro amp?
4.Can a BFD fed by my receiver LFE output increase gain to the pro amp?