AVS Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
417 Posts
Discussion Starter #1
Hi,

Does anyone know to what frequency the subsonic filter on BASH plate amps is set to?
I have the BASH 300s, and I wanna know if it's possible to reach 16hz with it.

I already designed a box tuned to 20hz for the Infinity 1260, but I just saw a thread where a 170L 16hz build was mentioned, based on this driver. All I need to do is make the box deeper, which should be easy enough, so I need to know if the plate amp won't just filter the extra work. :)
 

·
Registered
Joined
·
2,780 Posts
I think it is 18Hz for the BASH

Not 100% sure but a few years back I was looking at plate amps and that frequency popped in my head.

Good luck with your build.
 

·
Registered
Joined
·
417 Posts
Discussion Starter #3
I think it is 18Hz for the BASH

Not 100% sure but a few years back I was looking at plate amps and that frequency popped in my head.

Good luck with your build.
I've seen people mention 17.7hz, 22hz, 20hz, 18hz and 16hz. I'm looking for actual data from the manufacturer, but it's hard to find. Oh well, I've already printed the sketch for the 20hz 127L box for the carpenter, it should do 16hz at 100db which is good enough I guess.
 

·
Registered
Joined
·
4,856 Posts
If you can get hold of a the docs for a BASH 300, it also includes changing out 2 resistors that , iirc, lower the HPF,
there are like 4 or 5 options,

worth the search

YMMV

added: at PE you can read about the changes that will boost the bass starting at 20 and above
BUT: you can't AFAIK, change the HPF.

HTH
 

·
Registered
Joined
·
417 Posts
Discussion Starter #5
If you can get hold of a the docs for a BASH 300, it also includes changing out 2 resistors that , iirc, lower the HPF,
there are like 4 or 5 options,

worth the search

YMMV
The PDF was easy to find ('bash 300s pdf' on Google) but it only includes information regarding bass boost modification. Nothing about the HPF as far as I can tell.

How would I know where to set the HPF, though? What should I prevent the sub from producing? Its -3db point is at 19.5hz at 103db or so, but it should still produce 16hz at 100db - so is it OK if the HPF is set to 16hz?
 

·
Registered
Joined
·
4,856 Posts
^ IDK

what is the roll off of the built in HPF on the 300?

Will you be using REW wrt placement, and EQ?, etc.
 

·
Registered
Joined
·
21,336 Posts
The PDF was easy to find ('bash 300s pdf' on Google) but it only includes information regarding bass boost modification. Nothing about the HPF as far as I can tell.

How would I know where to set the HPF, though? What should I prevent the sub from producing? Its -3db point is at 19.5hz at 103db or so, but it should still produce 16hz at 100db - so is it OK if the HPF is set to 16hz?


the manual states the default values for the high pass filter. I've highlighted them in red.





that filter can be modeled in winisd. take any enclosure (I used a random sealed box) and under the "advanced selection" choose "force flat response. that should give you a perfectly flat line on the magnitude response tab.

then add filter: highpass (user specified fc and Q), then enter n=2, fc=17.7hz, q=1.00

that will give a response that looks like this:




so this filter provides a 1db increase of "bass boost" before rolling off at a q=1.00 rate. the -3db point relative to zero is 14hz.


this is one place where pictures would be worth a 1000 words, but the manual is what it is. :)
 

Attachments

·
Registered
Joined
·
417 Posts
Discussion Starter #8 (Edited)
^ IDK

what is the roll off of the built in HPF on the 300?

Will you be using REW wrt placement, and EQ?, etc.
I might get a miniDSP. I don't plan on buying a mic for it for now, though.

the manual states the default values for the high pass filter. I've highlighted them in red.





that filter can be modeled in winisd. take any enclosure (I used a random sealed box) and under the "advanced selection" choose "force flat response. that should give you a perfectly flat line on the magnitude response tab.

then add filter: highpass (user specified fc and Q), then enter n=2, fc=17.7hz, q=1.00

that will give a response that looks like this:




so this filter provides a 1db increase of "bass boost" before rolling off at a q=1.00 rate. the -3db point relative to zero is 14hz.


this is one place where pictures would be worth a 1000 words, but the manual is what it is. :)
Thanks, so therotically the sub will product sounds down to 14hz, so is it worth adding 30cm of length to make the sub produce 16hz at 105db, instead of 100db of the current design?
It's already 154 litres gross. :D

Can I just get a miniDSP instead to get that boost at 16hz?

Thanks.

Edit: strangely, after adding the high pass filter with 17.7hz cutoff (2nd order high pass), it shows 16hz at 105db on the SPL graph, on the 154 litre gross box (125.5 litres net).

Either way, I'll go with the smaller box. I should remind myself that I'll be blown away either way, as this is my first sub ever (commercial or otherwise), and I did have my eye on a simple Polk PSW10 on the first place and then things went downhill due to greed. :D
 

·
Registered
Joined
·
21,336 Posts
the port would end up being so long that the first port resonance will likely be down near the pass band and the output required to make those very low notes worthwhile needs to be pretty high, so with all that considered, I'd probably stick to the path that you are on. BUT, if you want to lower the tuning a little, feel free to experiment. :)


whatever course you choose, I wouldn't be boosting frequencies under the tuning frequency for a ported cab. driver excursion can get out of control pretty quickly.
 

·
Registered
Joined
·
417 Posts
Discussion Starter #10 (Edited)
whatever course you choose, I wouldn't be boosting frequencies under the tuning frequency for a ported cab. driver excursion can get out of control pretty quickly.
What I actually meant was to reduce the volume of frequencies above the ones I want to increase, and then crank up the overall volume of the sub.

But it says 100db at 16hz - is that good? A pic I just saw states it's as loud as a motorcycle - but is it a 125cc scooter or a Harley? :D

Also, why is it that adding the high pass filter as per your instructions increases the overall volume and moves the -3db point to 14hz (!) from the previous 19hz?

 

·
Registered
Joined
·
21,336 Posts
something went awry.


green is a 127 liter 20hz cab (with an arbitrary 1262 driver) and NO filters.


red is the same cab and driver with the high pass filter.





maybe what happened is the option for "force flat response" is still turned on on the advanced tab. you only want to do that if you want to see what the filter does all by itself. when you want to see how the filter applies to your project, just set the project up and make an identical copy as you have, and then add the highpass.


also, cutting the higher frequencies and raising the overall level is IDENTICAL to boosting the lower frequencies IF 1. neither approach results in clipping the signal, and 2. the resulting frequency response is the same.


as to how loud those very low notes will sound, equal loudness contours provide a little guidance:


https://en.wikipedia.org/wiki/Equal-loudness_contour


at 20hz, you need about 100db for it to sound 'about as loud' as a 60db tone at 1khz. that's why some guys shoot for 120db or more for the bass when a 95db tone at 1khz is ear splitting loud.
 

Attachments

·
Registered
Joined
·
417 Posts
Discussion Starter #12
something went awry.


green is a 127 liter 20hz cab (with an arbitrary 1262 driver) and NO filters.


red is the same cab and driver with the high pass filter.





maybe what happened is the option for "force flat response" is still turned on on the advanced tab. you only want to do that if you want to see what the filter does all by itself. when you want to see how the filter applies to your project, just set the project up and make an identical copy as you have, and then add the highpass.


also, cutting the higher frequencies and raising the overall level is IDENTICAL to boosting the lower frequencies IF 1. neither approach results in clipping the signal, and 2. the resulting frequency response is the same.


as to how loud those very low notes will sound, equal loudness contours provide a little guidance:


https://en.wikipedia.org/wiki/Equal-loudness_contour


at 20hz, you need about 100db for it to sound 'about as loud' as a 60db tone at 1khz. that's why some guys shoot for 120db or more for the bass when a 95db tone at 1khz is ear splitting loud.
So... I didn't go to the carpenter today. I woke up earlier than usual to go there before work, but my car had a flat. :D

So to recap... Would you recommend the 127 build with 20hz tuning, or 170 litre with 16hz tuning?

The 170 litre box seems to yield lower volumes above 20hz compared to the 127 litre box, but below 20hz it wins. You mentioned earlier that the port might be too long - were you referring to the 170 litre box tuned to 16hz?
 

·
Registered
Joined
·
21,336 Posts
with 1-4 cabs, I'd probably suggest the higher output and the higher tune, so in your case, 127/20hz.
with more than 4 cabs, the low frequencies may start to have enough output to come through, so it would be more of a personal preference/coin flip/pick what you want type thing. :)
 

·
Registered
Joined
·
417 Posts
Discussion Starter #14 (Edited)
with 1-4 cabs, I'd probably suggest the higher output and the higher tune, so in your case, 127/20hz.
with more than 4 cabs, the low frequencies may start to have enough output to come through, so it would be more of a personal preference/coin flip/pick what you want type thing. :)
Good idea. I forgot that our ears are less sensitive to lower frequencies so maybe 105db at 16hz just isn't enough.

I'll go for the 127/20hz build then. Going to the carpenter in a few minutes. :)
 
1 - 14 of 14 Posts
Top