Bass boost in portable active speakers?

[Dominique]

Hello,

I'd like to build some rather small portable active speakers.
Because of the small size (bass lack), I think about measuring the frequency sweep and boosting the bass a bit just where it's falling down. Nothing brutal, just a bit, so the bass would go deeper (maybe 10Hz deeper at-3dB) than the size of the housing would let you expect.

I just wonder if this would rise the bass' distortion significantly?
I'm no boom boom fan, but rather want a clear sound.

What do you think?
Cheers,
Dominique

[sreten]

Hi,

you are talking about 4th order sealed alignments or sixth order reflex alignments.

Both methods require an overdamped speaker alignment
and an active high pass filter with a Q of ~ 2.

The 6th order reflex alignment has the highest bass output capability.

Correctly implemented distortion is not an issue, transient response perhaps is.

/sreten.

[Dominique]

Originally posted by sreten

The 6th order reflex alignment has the highest bass output capability.

Ok, so I'm talking about this one
Why "6th order"? Does the filter has to be 6th order?
To "overdamp", do I simply choose a driver with a higher damping factor, or can I adapt other parameters in the bassreflex system?

Well, I'll look for a book in the library tomorrow. It seems more complicated than I thought! And I don't want you to do all the work for me!

Cheers,
Dominique

[johninCR]

MaxxBass is what you need, because small portables aren't going to give you real bass anyway. Check out waves.com

[sreten]

Originally posted by Dominique

Why "6th order"? Does the filter has to be 6th order?
Dominique

Hi,

A classsic flat 6th order aligment :

The speaker is a bass reflex with a port tuned lower than normal.
the overall output is 6dB down at the port frequency.
To this you add at line level a 2nd order high pass filter with Q=2,
and set at the same frequency as the port tuning.

The overall speaker will now have a sixth order bass rolloff.

Personally I think the above will sound somewhat boomy, I'd go
for a even more overdamped bass response - say 9dB down at
the port frequency to become the - 3dB point.

If you go for the classic alignment I'd make Q adjustable.

/sreten.

[Dominique]

Now it's clearer to me. Now I'll start reading about filters and loudspeaker theory and probably I'll come back later with some questions or even my finished project.

I just had the idea of measuring the frequency response of some tiny speakers I have here. Then playing music from the computer and apply software filters to see how they'd sound "flattened out". I had some DX plugin somewhere especially for that purpose if I remember well.

Thanks, sreten!

@johninCR
I didn't want to use the loudspeakers with the computer exclusively, so a plugin like MaxBass wouldn't suit me!

Cheers,
Dominique

[sreten]

Originally posted by Dominique
Now it's clearer to me. Now I'll start reading about filters and loudspeaker theory and probably I'll come back later with some questions or even my finished project.

Hi,

download WinISDPro and use the filter/EQ (user specified) to model this.

/sreten.

[johninCR]

Dominique,

For portable use, the way to go would be to convert a bunch of your MP3's using MaxxBass for use on the portable system instead of using one of the hardware solutions.

What it does is take the fundamental bass notes that your system can't play and add in the harmonics (that your system can play), which fools your ears/brain into interpreting that the fundamentals are being played. In essence you hear bass that's not there.

My problem with the Waves products is the high price.

[Dominique]

Originally posted by sreten

download WinISDPro and use the filter/EQ (user specified) to model this.

Ok, will do! thanks!

Originally posted by johninCR
Dominique,

For portable use, the way to go would be to convert a bunch of your MP3's using MaxxBass for use on the portable system instead of using one of the hardware solutions.

What it does is take the fundamental bass notes that your system can't play and add in the harmonics (that your system can play), which fools your ears/brain into interpreting that the fundamentals are being played. In essence you hear bass that's not there.

My problem with the Waves products is the high price.

Ah, now I get your point! Indead a good idea if the loudspeakers were mostly meant for mp3 use!
But I want to build a more universal solution!

And yes, Waves products are great, but expensive unfortunately! I think that other plugin makers have similar products to MaxxBass, which should be cheaper.

Possibly I'll be back later with questions again!

Cheers,
Dominique

[Dominique]

Hi again!

Sreten,

I played a bit with WinISDpro like you suggested. Very nice and easy to use!
First, I chose a wideband chassis that's easily available here, rather cheap, but seems to be pretty good for the price: Visaton FR10-8
Then I found the right parameters to lift the bass where the chassis already goes down to make the overall frequency transfer function as even and going as deep as possible.

Your highpass filter suggestion made a nice difference when I chose "SOS, user specified fc and Q".
What does SOS mean (probably: second order ... ?) and how does that filter type look like, schematic-wise? Just a capacitor and an inductor? When I chose a different filter type, e.g. Butterworth, that helping bass bump didn't appear.

Sorry to ask you questions again! I just know roughly about filters, all those different types have always confused me... Linkwitz, Bessel, Butterworth...

Cheers,
Dominique