Advice required for low frequency bass.

[Silent Screamer]

Currently I am in the process of building some 3 way mains, but I would like to set up a dedicated 4th way just for movies (I have a Ground Sound DCN28 4 way active cross over).
My first attempt at building a sub was in the late 90’s using a pair of Response 12” carbon fibre drivers in an isobaric configuration in a 32mm thick MDF cabinet with bracing, with a Jaycar Play Master 300w amp.
Well to tell you the truth I was somewhat disappointed with the result, it was low in volume and quite muddy sounding.

I recently solid my Sonus Faber Gravis (1 active / 2 passive version) sub to the guy I made the first speaker for and got the sub with the 2 x Response 12” drivers back to play with. I have done a bit of reading and I am somewhat intrigued by the tapped horn design.
I also have another 2 x 10” Vifa coated paper drivers from around the same era just collecting dust that I never used.

I was just wonder if I could repurpose either of these pairs of drivers into a half reasonable sub. Is the tapped horn the way to go, or are there better configurations for this purpose?

Sorry about the poor quality phone photos...

 

[weltersys]

I was just wonder if I could repurpose either of these pairs of drivers into a half reasonable sub. Is the tapped horn the way to go, or are there better configurations for this purpose?

Post the T.H. parameters for your drivers, desired LF response and size restrictions and you may get some good advice.

That advice would probably come from someone that loves to play with Hornresp.

I have a love/hate relationship with Hornresp because I must use an old and slow Dell PC computer rather than the Mac computers I normally use, hate the Windoze emulation of the Mac OS.

Love Hornresp, wish it ran on the Mac OS.

Art

 

[Silent Screamer]

Jaycar 12 inch Carbon Fibre Cone subwoofer
Jaycar Part no: CS-2246
Fs: 21.6 hz
Qms: 12.29
Qes: 0.294
Qts: 0.288
Vas: 220 litres
Xmax: 6 mm
Sd: 494 sq cm
Re: 3.5 ohm
Z: 4 ohm
Pe: 200 W
SPL: 93 dB/watt@1m

Vifa M26WR-09-08
Fs: 26 Hz
Qms: 2.82
Qes: 0.36
Vas: 130 litres
Xmax: 6.5 mm
Sd: 337 sq cm
Re: 5.9 ohms
Le: 1.8 mH
Z: 8 ohms
Pe: 105 watts

LF ballpark ~37Hz - 100Hz
Size not restricted... whatever is necessary to do the job properly.

 

[AndrewT]

I look forward to seeing the Hornresp results for these two drivers.

Both are lowish in Xmax and the Jaycar is lowish in Qts.

I too have tried Hornresp and I can't get my head around the instructions and the icons to press to get sensible outputs.

 

[Silent Screamer]

I haven't tried to use hornresp yet (other than installing it and plugging in what values I know). I know nothing about the theory behind the design of this speaker type, that is why I am keen to know more about it.

I went into the advanced section on Bass Box and calculated some of the unknown values (using the calc button).

 

[weltersys]

I haven't tried to use hornresp yet (other than installing it and plugging in what values I know). I know nothing about the theory behind the design of this speaker type, that is why I am keen to know more about it.

I went into the advanced section on Bass Box and calculated some of the unknown values (using the calc button).

Like other horns, TH need a high BL to work well, the relatively low BL of the woofers you have may work OK in a ported box, but more magnetic strength is needed to push the mass in a TH.

In general TH use a woofer with a higher Fs than the Fb, while ported boxes are usually best with Fb pretty close to Fs.

Your woofers are not optimal for a desired Fb of 37 Hz, which is much higher than what most people would want for home theater.

There are lots of movie sound effects in the 20 Hz range, either of your woofers could be tuned that low and won't unload so badly.
T-Rex foot thumps are an octave below 37 Hz, they will make your speakers flap like a pinned bird if tuned that high.

Art

 

[weltersys]

I too have tried Hornresp and I can't get my head around the instructions and the icons to press to get sensible outputs.

Best way to get your head around box design using Hornresp is to copy the input parameters of a known working box (there are hundreds in various posts) then substitute the driver you are considering and compare the results.

 

[bjorno]

Hi,

FYI:

b🙂

 

[Silent Screamer]

Thanks weltersys it doesn’t really matter if they are not that usable, I was only going to try get some experience with them, but I might just ebay them instead.

These are the drivers that were recommended to me…
What I am looking for is sharp clear bass, without it being muddy sounding.

I have invested a lot of money into audio gear so the fact that they are $1000+ each is not a major concern, it’s all about the clarity.

I was trying to not be greedy with asking for 20Hz because I have read several times that 37Hz is the magic number and all you need, but from what you say that might be for music, not for home theatre.

I failed miserably (IMO) on the first attempt to build a sub and would really like to avoid making bad driver and cabinet choices again.

 

[Silent Screamer]

could someone pleas simulate the 15" speaker for me in hornresp. Once I know what it should look like I should be able to work backwards from there and better understand the program. Thanks in advance.

 

[NEO Dan]

You can create ported and sealed systems for your drivers in Hornresp, use them as a reference and progress from there.

 

[Silent Screamer]

How do you create sealed and ported speakers in Hornresp? I thought you could only simulate TH.

 

[bjorno]

How do you create sealed and ported speakers in Hornresp? I thought you could only simulate TH.

Hi, Take a look at the first and continued at the second of submitted pictures were two different ways are used for simulating BR boxes in HR:

http://www.diyaudio.com/forums/subwoofers/214201-tube-woofer.html#post3054581

b🙂