The Drake without notch filter?

[Radius]

Hi everyone!

Popping in here again with some questions.

First, a little background info. I've been in the middle of the home remodel from hell for about 2 years now so all of my books, woofer tester, my main computer, etc, are all in storage. There is light at the end of the tunnel though!

I have been doing some cabinet making in a friend's garage building closet organizers and such. I have needed a new subwoofer for my HT system for quite some time. Since I really don't have room to do this kind of work at home I thought I would build one while I had all my stuff out and had left over materials, laminate, etc, easily available. I won't be able to really test it, but at least it will be built and I could put it into storage with the rest of my gear until my house is done.

So, that being said, I was browsing the sub projects and The Drake looked like a good fit.

However, I already have an external Crown amp that I use for my subs. It's a beast, but it does not have the notch filter that is in the PE sub listed in the project. As a general rule, I let the AVR handle crossover duties in my HT system.

Will the absence of the notch filter appreciably affect the performance of the sub? If so, perhaps I can build a passive filter to replicate it? Can someone help me with the design of the filter?

Or should I just build it to the dimensions provided and see how it sounds after I get my house done and the system all put together?

Acually, now that I think about it room design, etc, will all affect the performance of the design, so maybe this is the best option.

What say ye the experts?

Thanks,
Michael

[Radius]

Anyone?

Would really like to know how the absence of a notch filter might affect the performance of this build.

Thanks,
Michael

[Pete Schumacher ®]

Anyone?

Would really like to know how the absence of a notch filter might affect the performance of this build.

Thanks,
Michael

Wouldn't worry about it. At most sub XO frequencies, and the typical 4th order roll off provided by most AVRs, you won't have to worry about any resonance.

I used the RSS315HF-8 as a woofer in a 3-way, crossing at 350Hz, 2nd order. I didn't notice any problems, but I wound up putting a notch in anyway, just to be sure.

[Radius]

Ok, perfect..

That's about what I figured.

One more kinda dumb question. I plan to use an 8 ohm driver to reduce the load on my amp. I have plenty of excess power for this sub. This shouldn't affect the enclosure design should it? After all, the 4 ohm version and the 8 ohm version *should* be very close to the same other than the impedance, right?

Thanks,
Michael

[Pete Schumacher ®]

Ok, perfect..

That's about what I figured.

One more kinda dumb question. I plan to use an 8 ohm driver to reduce the load on my amp. I have plenty of excess power for this sub. This shouldn't affect the enclosure design should it? After all, the 4 ohm version and the 8 ohm version *should* be very close to the same other than the impedance, right?

Thanks,
Michael

That's correct, if the TS parameters are the same, Vas, Qts, Fs. If they vary significantly, you may want to take a closer look and model up before building.

[Radius]

That's correct, if the TS parameters are the same, Vas, Qts, Fs. If they vary significantly, you may want to take a closer look and model up before building.

Turns out it's a moot point. There doesn't appear to be an 8 ohm version of the HO version of this driver. No biggie I'll just have to turn the gain of the amp way down.

Thanks for your help,
Michael

[PunkSweeper]

Wouldn't worry about it. At most sub XO frequencies, and the typical 4th order roll off provided by most AVRs, you won't have to worry about any resonance.

I used the RSS315HF-8 as a woofer in a 3-way, crossing at 350Hz, 2nd order. I didn't notice any problems, but I wound up putting a notch in anyway, just to be sure.

I think Radius might be referring to how Darren used the parametric EQ on the 1000 watt plat amp to force the f3 lower. Absence of this could indeed affect the subs performance.

[dwigle]

I can't find my notes right now but I think I'm not using the notch filter but am using at least +6db eq to get in-room response flat to about 30Hz. Given that amount of boost, the Drake requires a bunch of power.

I have the 1000w (really about 540w) amp and at very high volume the clipping indicators flicker - but I can't hear anything nasty or audible other than LOUD. I should say though that I rarely use anywhere near that power and the output is pretty amazing for a 13.5" cube.

[Radius]

I think Radius might be referring to how Darren used the parametric EQ on the 1000 watt plat amp to force the f3 lower. Absence of this could indeed affect the subs performance.

That would be correct.

And of course I just ordered all the parts last night. Uh oh..

Do I need to build a different size enclosure? I can easily build a larger enclosure if needed since I have the space.

Does anyone have the time to do a quick model of this driver for me? All of my stuff is in storage and I am just so buried at work and at home. Is there an online modelling program/script I can plug the T/S parameters into?

I definitely want the f3 on this sub to extend down to 30hz or so since this will be for home theater use.

Thanks again,
Michael

[Operandi]

You'll need to go with quite a bit bigger cabinet and ported if you want to keep the same extension without the boost filter. For reference I built a 2.5 cuF cabinet with a 4" x 15.5" port for the Dayton 315HF, F3 is somewhere right below 30Hz.

I'm sure someone could cook up a simulation for you, might want to start a new thread though.

[Brent_S]

Radius, my 315HO-4 is about 5 years old so take what I'm about to say with a grain of salt. The T/S parms published in 2005 for the 315HO-4 produce fairly different models than the current T/S numbers. No clue if the driver has actually changed that much or if it's just the sample(s) that were measured differently.

From memory, my version models an f3=45ish Hz, -13@20Hz in 1 ft^3 sealed, including the 1dB boost around 22Hz provided by the stock BASH-300's rumble filter . The current 315HO-4's T/S parms model around f3=60ish Hz, can't remember how far down it is at 20Hz.

Just last night, playing with my new EMM-6 (calibrated by Cross-Spectrum), I measured my 315HO-4 in room (1.2 ft^3 gross sealed). Close mic'd, about 1/2" off the dustcap I was down about 10dB at 20Hz relative to the pink noise I used for setting the reference level. At the listening position, 15' away with the mic at least 5' from any boundary, it actually measured +4dB *above* the reference tone. The response was naturally wonky due to the room being involved, but overall I'd call it relatively flat down to 20Hz in room. Naturally, room gain can vary with room construction and dimension, but I actually didn't expect this much in my room...22'x20'x9', one wall is really a two story foyer/open staircase/catwalk so the longest dimension is closer to 35', sub is mid-wall, not corner loaded. And even though I've only got 300 watts on tap, I've never found it wanting for SPL.

That's a long winded way of saying IME, you'll probably be happy even using your Crown, especially if your receiver/processor has a flavor of room correction EQ that works on the sub channel. Assuming the current shipping 315HO-4 is still the same as the 2005 flavor, despite the different published T/S parms.

-Brent

[dwigle]

I think he's been talking about the HO not the HF. If so, .6-.8 ft sealed with EQ works well.

I modeled the HO vented and at 1.2ft it looks good but tuning at 31hz yields a really long 4" vent. A 3" vent length is manageable but port noise is likely a problem.

I haven't heard from anyone lately running it vented - hopefully someone who has will contribute.

[Radius]

I think he's been talking about the HO not the HF. If so, .6-.8 ft sealed with EQ works well.

I modeled the HO vented and at 1.2ft it looks good but tuning at 31hz yields a really long 4" vent. A 3" vent length is manageable but port noise is likely a problem.

I haven't heard from anyone lately running it vented - hopefully someone who has will contribute.

Yes, I am talking about the HO..

Dang it! Wish I could model this driver, but I can't do it at work and I have no computer at home. Argh..

I was thinking of just building a sealed 2.2 cu ft box without compensating for driver volume and letting it rip.

Yes, I will be using a Pioneer Elite VSX-32 with MCACC room compensation calibration.

What do you guys think? Think I'll be ok with 2.2 cu/ft?

Thanks,
Michael

[dwigle]

Yes, I am talking about the HO..

Dang it! Wish I could model this driver, but I can't do it at work and I have no computer at home. Argh..

I was thinking of just building a sealed 2.2 cu ft box without compensating for driver volume and letting it rip.

Yes, I will be using a Pioneer Elite VSX-32 with MCACC room compensation calibration.

What do you guys think? Think I'll be ok with 2.2 cu/ft?

Thanks,
Michael

I'll work on it and get back to you.

[dwigle]

Sealed at 1.85 ft net volume, F3 is 60hz, F10 is 27hz. Q is .55, not very well controlled with cone excursion exceeding xmax at 500w. Without EQ this is not very appealing. If you want to go sealed with this driver consider .6-.8 ft net and buy a reckhorn EQ and subfilter for $60.00 to use with your crown.

Vented, 1.8ft net is better but if you're going that large, I'd go a little bigger and use the HF driver.

[Radius]

Sealed at 1.85 ft net volume, F3 is 60hz, F10 is 27hz. Q is .55, not very well controlled with cone excursion exceeding xmax at 500w. Without EQ this is not very appealing. If you want to go sealed with this driver consider .6-.8 ft net and buy a reckhorn EQ and subfilter for $60.00 to use with your crown.

Vented, 1.8ft net is better but if you're going that large, I'd go a little bigger and use the HF driver.

Dang it..

Unfortunately for me I already ordered the HO units in anticipation of building the Drake..

So sealed without EQ is a poor choice? Keep in mind that my AVR does have and I use the room EQ functions included in MCACC.

With that being said, I can also build a ported enclosure, I just need to know internal volume, port size, length, etc.

And another twist - how would firing the driver at the floor effect things?

Thanks very much for taking the time to model this driver for me.

Michael

[dwigle]

Dang it..

Unfortunately for me I already ordered the HO units in anticipation of building the Drake..

So sealed without EQ is a poor choice? Keep in mind that my AVR does have and I use the room EQ functions included in MCACC.

With that being said, I can also build a ported enclosure, I just need to know internal volume, port size, length, etc.

And another twist - how would firing the driver at the floor effect things?

Thanks very much for taking the time to model this driver for me.

Michael

A small sealed enclosure, .6-.8ft with eq works well. Check your receiver to see if you have a parametric eq function. Or, like I said, a Reckhorn eq http://www.creativesound.ca/details.php?model=B-1 is a cheap and effective alternative.

I'm not sure you'll like this driver ported especially without a high pass filter below tuning frequency. The cone excursion is not well controlled and you could do some damage.

[Wolf]

The HO will be fine vented. For inspiration, you can look up the 'Smackerel' that uses the RSS2565HO-4 in a vented cab.

The HO's will work boosted-sealed or vented just fine. I think the Reckhorn from CSS will do what you want sealed.
Later,
Wolf

[dwigle]

The HO will be fine vented. For inspiration, you can look up the 'Smackerel' that uses the RSS2565HO-4 in a vented cab.

The HO's will work boosted-sealed or vented just fine. I think the Reckhorn from CSS will do what you want sealed.
Later,
Wolf

I've come up with a scheme to build an IB system in my FR so I have been thinking of pulling the HO out of the drake and trying a vented alignment for another system.

At 1.2 ft and at 31hz tuning the FR is flat but the vent is waay too long. Increasing the box size and reducing the tuning freq puts the vent length acceptable but there is a huge (3db) hump at about 32hz.

Are there other options?

[Radius]

A small sealed enclosure, .6-.8ft with eq works well. Check your receiver to see if you have a parametric eq function. Or, like I said, a Reckhorn eq http://www.creativesound.ca/details.php?model=B-1 is a cheap and effective alternative.

I'm not sure you'll like this driver ported especially without a high pass filter below tuning frequency. The cone excursion is not well controlled and you could do some damage.

So I'm sitting down figuring out my dimensions since I planned on getting started on this enclosure tomorrow.

I don't see a spec on the displacement of this woofer. Anyone have an idea or a good rule of thumb?

Thanks,
Michael