Hey I just purchased a Hertz HK250d 10" sub and wow nice speaker. Trouble is I cannot find any specs on it online and still waiting a response from Hertz. Anybody have some idea of what enclosure this would work best in? It goes very kow with ease in a ported box tuned to 46Hz. With my previous sub I had to boost 40Hz by 8db. With this one its set flat and sounds good. Going for sound quality.

 

For sound quality you want it tuned in the low 30s. 46hz will be a bit peaky and require a boost on the bottom end.

 

Ihc, yeah I believe you but this sub seems to put out the lower frequencies very well. It is actually the higher ones, 60-70 Hz where it dips a bit. So does that mean this sub is better suited in a sealed box?

 

That's weird but all that matters is how it sounds in real life. I'll model it just for my own curiosity. If you're not having to boost much anywhere you're good. How is it facing?

 

Its in a ported box facing the back. I stuffed the port with a towel to reduce the 40-50hz which has worked but i hve to turn the gain up nearly 3/4 now. Sounds alright though. Its an hx250d not hk like the guy ibought from told me.

 

http://www.hertzaudiovideo.com/Doc/pdf_hx250d.pdf

So let me get this straight...your box is tuned to 46hz!

One-note wonder comes to mind. Seal it up in about 1cube or slightly bigger if you can. Or build a box tuned in low 30's or high 20's. I can model it in WinISD when I get home

 

Ya those specs are for the newer one. Freq response of my older orange magnet sub strts at 23. I guess the tuning does explain it and why stuffing the port and turning the gain u improved the sound .

 

Stuffing the port means you're basically running a sealed box. If you could tune it lower, you'll enjoy the efficiency of the ported box in the range that you need it. With the tuning frequency, it's no surprise that stuffing the towel in it lowered those frequencies. It will probably amaze you how much better it will sound once it's tuned lower.

 

Well I guess I know what my project is this wknd. It has rectangular port in corner so how far should i extend that? Im guessing it could extend to around 9" from pprox 5.

 

Wait what? Can you draw this or do something in Paint? lol. I can tell you what you need to do if you give me the dimensions of the box.

 

It is bassworx hpr10. 1.25 cubic feet. I woud postic or send a filefil

 

Except im using a piece of shit replacement phone. The old xperias are junk

 

Ok its not so bad with different browser but still miss my play.

 

Judging by this pic, this is what you have. I can't see the port inside, but it looks like the mdf might just go straight back and stop a few inches before it reaches the back of the box...which makes sense. A short port, especially one like that, would make it tuned VERY high. You'd need to extend it off a certain distance left to make the tune lower. I'll see what I can come up with but I'm not quite sure how you'd do that without taking the box apart...

 

The easiest way I can think of to lower tuning frequency is to keep the same length but reduce port volume. Can you stuff something like a 1.5" thick piece of wood on the bottom of the port that runs the length of the port? This would lower tuning frequency but by how much I have no idea. Should be significant. Eventually you will run into port noise but it might be ok.

 

I'll model it right now if the OP can tell us the distance between the port boards.

 

The red words above the port say "I need these distances". The long line means I need the distance from the front of the box until the length of the port piece of MDF ends near the rear of the box

 

If my calculations are correct lol..

That port should be 1.25" in width and go 11" deep.

Good idea Matt. I've modeled it and by doing what you said he could knock the tuning down to 30hz

 

Box dimensions:

17.25 x 12.75 x 15.25" (12.25 top depth)

Port dimensions:

3.75 x 3" ;

Port length:

8"

 

Oh 2.5 would be the median height of the port

 

Thanks for everyone's help. i think I was able to determine through winisd that 33hz would be the optimum tuning frequency for this sub in the box that it's in. To get there I would need to reduce the port size by .25" in width and increase port length by 6" Could this be done by making an L shape extension to the existing port?

According to the gain plot, it would be flat down until 31hz... isn't that good?

 

Yes that's good. But I just realized that that port doesn't extend the box length OR height. You could probably get away with buying a sealed box and buying an aero port and just going that route. Would be cheap and likely easier.

 

Well for now i stuffed the port and boosted 40hz by 6db

 

That would be great for SQ. You might want to reduce port diameter in a temporary way until you get port noise. You might get lucky and get away with just a reduction in diameter without changing the length.

 

I think that is a good idea. Probably a single 1 by 4 cut to two 8" lengths would do nicely. Does it ever sound good. Didnt know they could sould like that. This sub is loud and clear.

 

Oh im powring it with 500 watt rms mono amp so here is another question: should i run the amp gain high and reduce the signal or turn the signal up and lower the amp gain?

 

IHC is correct. Instead of extending the port length, which is pretty much impossible now that it's already built, you can just reduce the ports diameter. If the port was like an ordinary port which ran the height of the box I could tell you exactly how much to reduce te diameter...but that's a weird box.

As far as your amps gain..what do you mean by "signal"? I'm assuming you have an adjustable LOC yes? The amp gain isnt a volume knob, it's to match the voltage you need to have a distortion free experience. Are you wired into an LOC back near the sub or what??

 

No loc. Just the amps high level input. It seems i can turn the amp gain to the mac without losing effect of the gain and is distortion free maintaining dynamic range. I have it set at approx 1.5v or 7% right now and HU set at -1. Using sound stream on android phone to ear in crossover and level. 20hz to 200hz sine sweep sounds smooth. Also backed off the boost at 40hz to 0

 

Should read 70% up there

 

And .75v

 

Ok well i think i have this figured out now. Sounds very good as is but i may tinker with the port or see about a small sealed box

 

Sound form not sound stream

 

Keep in mind, with such a high tuning frequency, you will be going below the tuning of the port causing the sub to unload and excursion will be the same as if it's freeair.

With it the way it is, it's not a bad idea to use a subsonic filter from 40hz and down or just keep the port plugged up until you tune it lower.

 

Yeah im leaving it plugged for now. Sounds way better that way than with the tuning as is. I do have a small sealed truck box not doing much so i may try in there.

 

If you want a sealed box, the one you have should be great with the port plugged good. Larger boxes have many benefits including less power required, better SQ, and a flatter frequency response. The sub will go lower yet sound "quick" and "snappy".

 

If you're post amp then that gain is entirely to high. Our post-amp signal is like 4-5v,not 1.5v

 

Yes it does sound good. I still think it needs a boost in the 60hz range but it definitely goes deep with precision and yes speed.

 

I know and I was actually afraid to turn the gain up until recently. I may be wrong but my ears tell me I'm right. It would seem the most useful scenario in my case is reality and that is the input sensitivity dial has little to do with input sensitivity when the amp is connected via the high level input. See my sub has a sensitivity rating of 96db and I'm pushing it with probably around 450 watts rms or 900 peak. I've learned a whole lot of this stuff recently but I have fairly good hearing and I could barely detect the presence of a sub when the gain (input sensitivity) was set to 4-5v which is right near 0 gain or -?? (?). I took it to an installer and we figured out the sub sounded fine with no distortion when that knob was turn up to max so now it's at 70% and my HU control set to -1. My guess is my amp puts out less watts to the speaker the further that dial is from max. At my present setting that would be (.7*450) 315.

Tell me I'm not crazy?

One other thing. I started out with the stock sub still connected but got sick of the rattle then disconnected it. Rattle went away but so did the volume of the aftermarket sub. Again, I'm not an expert but without the stock sub connected I do not believe the high level inputs would receive the same amount of current due to high impedance values?

 

http://pdfcast.org/pdf/hx-250-d

Specs for my sub.

See the recommended sealed box sizes? 9 and 14 liters or 0.32 and 0.49 cubic feet.

my box is 35.4 liters. Based on those recommendations what would be best to get the flattest curve and maintain control of the woofer... 20 liters? Suppose I could just stuff the box I have as well...

 

If you like the way it sounds now, I wouldn't change anything other than to make sure the box is airtight.

The flattest response is going to be in the box you have it in now with it sealed. The motor controls the cone, so no worries there. Without the airspring to decrease efficiency, it's going to require less power for the same SPL down low. You will get the same SPL, just at a lower power level. It will also take less power to push it to it's mechanical limits so I wouldn't try and run the maximum rated power to it.