# Sub Experts Needed...



## Brunt (Aug 7, 2011)

Hello,

I recently purchased a sub from in ID company and a reputable one at that. Try to picture this:

This company makes a wonderful ported 15" sub which is 500w. They do not normally make one, but they built me a custom 15" sealed sub in a 20" cube, powered by the same 500w. 

After dialing it in and messing with settings, and even talking to the company...I come to this conclusion: I am completely underwhelmed by the sub's output. During one scene of the new Star Trek, there is a a bass heavy passage right after the opening credit. During this scene, before I could even feel or hear actual bass, I heard the driver knocking as it was being over driven. Keep in mind my sub gain was 12:00 and my AVR sub level was set at less than zero. So, after dialing it in per the company's instruction, the sub is now set so it won't make that noise...which is awesome...except that now the overall output and volume is almost worse than my old Polk PSW505. 

My question to you guys is this: What would make this sub behave this way? Over powered? Underpowered? Keep in mind, the company does sell sealed subs, which usually have more power than their ported cousins...but mine doesn't. I know sealed subs offer less output, but I've read in numerous locations that sealed subs also off the advantage of being incredibly hard to over drive because of the pressure and force being applied to the backside of the driver and it not being able to escape through a port.

Any thoughts would be greatly appreciated!!!


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## robbo266317 (Sep 22, 2008)

Do you know the model of the driver or it's parameters so we can model it? 
Also does the amp have a high pass filter or bass boost setting? If so what are they set at.

It's a bit hard to tell where the problem lies without knowing what it is capable of.
Cheers,
Bill.


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## Brunt (Aug 7, 2011)

robbo266317 said:


> Do you know the model of the driver or it's parameters so we can model it?
> Also does the amp have a high pass filter or bass boost setting? If so what are they set at.
> 
> It's a bit hard to tell where the problem lies without knowing what it is capable of.
> ...


Well...won't give driver because it will give away company name and I want to refrain from giving them a bad name right now until I trouble shott a bit more. The amp that it came with was the BASH 500w plate amp that you can find at PartsExpress I believe. No bass boost switch on amp itself and I am running the LFE signal from my AVR and not using amps crossover, as per this companiy's recommendation.


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## robbo266317 (Sep 22, 2008)

OK, I have your PM I will see what I can find out for you and hopefully do some modelling.

Cheers,
Bill.


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## eugovector (Sep 4, 2006)

I have a guess as to the company, but I'll keep that to myself. 

As you move around the room, ie change listening positions, do you still have no bass repose or do you start to hear the bass? Could be a positioning problem. You could also run a REW sweep to see if it's at all frequencies, or specific ones.


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## Brunt (Aug 7, 2011)

eugovector said:


> I have a guess as to the company, but I'll keep that to myself.
> 
> As you move around the room, ie change listening positions, do you still have no bass repose or do you start to hear the bass? Could be a positioning problem. You could also run a REW sweep to see if it's at all frequencies, or specific ones.


I hear decent bass when standing or sitting directly in front of the sub...within about 4 feet. Everywhere else it's pretty anemic.


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## robbo266317 (Sep 22, 2008)

I have been unable to find the parameters for the driver so I guess modelling is not possible.
Do you have access to a SPL meter or ECM mic to run REW to see what is actually going on? This can give you an instant comparison between the two subs and may highlight what the issue is.


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## chashint (Jan 12, 2011)

Brunt said:


> Hello,
> <<<<<<< snip >>>>>>>>>>
> This company makes a wonderful ported 15" sub which is 500w. They do not normally make one, but they built me a custom 15" sealed sub in a 20" cube, powered by the same 500w.
> <<<<<<< snip >>>>>>>>>>
> Any thoughts would be greatly appreciated!!!


Sounds like you speced it out and they custom built something for you that is not part of their standard product line, the parts may not be a match for this application or your expectations may be out of whack.

The box dimensions are pretty close to the standard dimensions of a Rythmik F15, if you buy their driver and amp and install them in your box chances are you will have something that sounds like the F15.
This may or may not be the sound you are looking for, but at least the engineering is proven.


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## fusseli (May 1, 2007)

chashint said:


> Sounds like you speced it out and they custom built something for you that is not part of their standard product line, the parts may not be a match for this application or your expectations may be out of whack.


This.

Sure you can slap any sub and amp into a box and run it. Doesn't mean it's automatically going to perform outstanding, by any means. It's also super easy to overdrive a sealed sub, which comes from one thing: too much power for the sub/cab combo. That 15 is probably better suited to vented in the first place, which can offer better cone control than sealed when matched with the proper HPF.

Also from what you describe of only hearing strong bass when close to the sub, that sounds like a placement issue... Are your mains on an HPF (or "small" setting) from your AVR as well? They should be if you're running a sub.


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## Brunt (Aug 7, 2011)

fusseli said:


> This.
> 
> Sure you can slap any sub and amp into a box and run it. Doesn't mean it's automatically going to perform outstanding, by any means. It's also super easy to overdrive a sealed sub, which comes from one thing: too much power for the sub/cab combo. That 15 is probably better suited to vented in the first place, which can offer better cone control than sealed when matched with the proper HPF.
> 
> Also from what you describe of only hearing strong bass when close to the sub, that sounds like a placement issue... Are your mains on an HPF (or "small" setting) from your AVR as well? They should be if you're running a sub.


Actually I disagree...by design its harder to overdrive a sealed sub. The driver in my sub is rated for 650w rma and supposedly is good for sealed or ported use...per the manufacturer. Waiting to hear back on my return options.


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## fusseli (May 1, 2007)

Brunt said:


> Actually I disagree...by design its harder to overdrive a sealed sub. The driver in my sub is rated for 650w rma and supposedly is good for sealed or ported use...per the manufacturer. Waiting to hear back on my return options.


Disagree all you like, physics is physics. Also, the subs thermal power rating has zilch to do with what will make it bottom out in a particular cabinet. "Good for sealed or ported" just means the sub has a moderate EBP.


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## Brunt (Aug 7, 2011)

fusseli said:


> Disagree all you like, physics is physics. Also, the subs thermal power rating has zilch to do with what will make it bottom out in a particular cabinet. "Good for sealed or ported" just means the sub has a moderate EBP.


Agree to disagree then...I have researched it as it seems you have and one of the benefis IMO seems to be with a proper sealed design is the difficulty of over driving the sub due to constant back pressure being applied to the driver. Of course, I'm assuming a properly tuned/sized cabinet and a driver intended for that use. As you said, it doesn't sound like they did much of that.


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## fusseli (May 1, 2007)

Brunt said:


> Agree to disagree then...I have researched it as it seems you have and one of the benefis IMO seems to be with a proper sealed design is the difficulty of over driving the sub due to constant back pressure being applied to the driver. Of course, I'm assuming a properly tuned/sized cabinet and a driver intended for that use. As you said, it doesn't sound like they did much of that.


Not trying to bash on the mystery company. It just sounds like this "custom build" was not a very well though out design. The only thing you can do about overexcursion is keep the gain set low or add an HPF, which you'd have to guess at without being able to model the sub.



FYI, here's an arbitrary example of what I was talking about:
Here are the excursion profiles of a sub in the _same volume_ box, sealed or vented. The sealed config bottoms out and "oil-cans" on deep HT rumbles. The vented config, with proper HPF added, will never bottom out.









Here's the sealed sub again, E.g. with 500W (yellow) shown to bottom out. The same exact sub with half the power (orange), 250W, isn't gonna bottom out. The pink has 500W still but an added HPF, it will not bottom out but it also suffers from the delay of the added filter, losing it's "tight sealed sound" down low.









That's the power of modelling, my friend.


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## Brunt (Aug 7, 2011)

fusseli said:


> Not trying to bash on the mystery company. It just sounds like this "custom build" was not a very well though out design. The only thing you can do about overexcursion is keep the gain set low or add an HPF, which you'd have to guess at without being able to model the sub.
> 
> 
> 
> ...


Hey, I don't care if you bash! Lol. I'm not keeping this thing if I can help it. The output is so anemic even before it bottoms that its a joke.


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## fusseli (May 1, 2007)

I edited my post with more detail since you read it 

You should definitely make sure you don't have a phasing or placement problem when you get a new sub. If you do have such a problem, the new sub will also sound weaker and/or boomier than it should.


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