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
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
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.
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.
sreten said:
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
MaxxBass is what you need, because small portables aren't going to give you real bass anyway. Check out waves.com
Dominique said:
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.
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
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
Dominique said:
Hi,
download WinISDPro and use the filter/EQ (user specified) to model this.
🙂/sreten.
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.
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.
sreten said:
Ok, will do! thanks! 🙂
johninCR said:
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
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
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
Dominique said:
Hi,
I thought the programmer had a sense of humour
and SOS has its usual meaning "save our souls".
The filter type is a standard second order highpass.
The only real variable for second order filters is Q.
And for each of the different types of filters, e.g. Bessel
there is a particular value of Q which means that type.
e.g. Q=0.7 = Butterworth.
As Butterworth is maximally flat it does not have a bump.
Any Q higher than 0.7 will have some form of bump.
For passive filters a series capacitor, parallel inductor to a resistive load.
For active filters you have a choice of topolology.
It may be possible to implement in the feedback
loop of the power amplifier, thats where I'd put it.
🙂/sreten.
Hi again!
Now it's been some time and I read more about loudspeaker theory, TSPs, measuring, also tried to find some clearly written and easy to understand info about filters.
(Also built a quick amp with an LT1210 which sounded great by the way)
But what I found on active filters was either very basic or else full of formulas and confusing long text, but less of helpful images!
So I didn't find an active 2nd order filter for q=2. I mostly didn't find any q given, but rather those names like Butterworth, Tchebychev... Which one is the q=2 one? 🙂
Yes, like you proposed, I'd like to go the active way. Putting the filter in the feedback loop would be nice.
I feel lame for asking, but I really didn't find out how to implement that filter yet. Could you maybe point me at it? The only thing I can tell from reading is that there seems to be more than one implementation when going the active way...
Cheers,
Dominique
Now it's been some time and I read more about loudspeaker theory, TSPs, measuring, also tried to find some clearly written and easy to understand info about filters.
(Also built a quick amp with an LT1210 which sounded great by the way)
But what I found on active filters was either very basic or else full of formulas and confusing long text, but less of helpful images!
So I didn't find an active 2nd order filter for q=2. I mostly didn't find any q given, but rather those names like Butterworth, Tchebychev... Which one is the q=2 one? 🙂
Yes, like you proposed, I'd like to go the active way. Putting the filter in the feedback loop would be nice.
I feel lame for asking, but I really didn't find out how to implement that filter yet. Could you maybe point me at it? The only thing I can tell from reading is that there seems to be more than one implementation when going the active way...
Cheers,
Dominique
Hi Dominique,
I'm ahead of you on this one, see this post :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=75974
If you require further clarification please ask.
🙂/sreten.
I'm ahead of you on this one, see this post :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=75974
If you require further clarification please ask.
🙂/sreten.
Oh, great!
Do you intend to build this too?
If yes, I could post more info about my project soon, if not, I think I'll only present it with pictures when it's finally built.
Now there are several filters proposed, for the one from "consort_ee_um", do you know how to calculate the valkues for the wanted frequency and gain? If not, I'll ask him in that other thread.
Do you think that circuit has advantages over the one I found?
Ok, sorry for not stopping to bother you with questions, but that topic is of great interest for me, it doesn't only help boosting the bass a bit, but it also limits the cone excursion for the very low frequencies which should be quite helpful for the small wideband drivers I intend to use!
At the moment I think of using either one of the Tangband W4-XXX (possibly 616) or the Monacor SPH-60X, as they provide a better bass than the Visatons I thought of first.
Unfortunately, they have a higher V as, but if the curve is too flat because of the high V as and low q of the speakers, I could compensate with a higher q in the active filter, couldn't I?
Thank you again! 🙂
Cheers,
Dominique
Do you intend to build this too?
If yes, I could post more info about my project soon, if not, I think I'll only present it with pictures when it's finally built.
Now there are several filters proposed, for the one from "consort_ee_um", do you know how to calculate the valkues for the wanted frequency and gain? If not, I'll ask him in that other thread.
Do you think that circuit has advantages over the one I found?
Ok, sorry for not stopping to bother you with questions, but that topic is of great interest for me, it doesn't only help boosting the bass a bit, but it also limits the cone excursion for the very low frequencies which should be quite helpful for the small wideband drivers I intend to use!
At the moment I think of using either one of the Tangband W4-XXX (possibly 616) or the Monacor SPH-60X, as they provide a better bass than the Visatons I thought of first.
Unfortunately, they have a higher V as, but if the curve is too flat because of the high V as and low q of the speakers, I could compensate with a higher q in the active filter, couldn't I?
Thank you again! 🙂
Cheers,
Dominique
Ok, I've put that handdrawed circuit in LTSpice and saw that it doesn't behave as complicated as I feared.
Gain is to set easily.
What a pity that there dual tunig capacitors doesn't exist, just like there are dual potentiometers, to finetune the frequency!
Cheers,
Dominique
Gain is to set easily.
What a pity that there dual tunig capacitors doesn't exist, just like there are dual potentiometers, to finetune the frequency!
Cheers,
Dominique
Hi,
reread the other thread. CEU's circuit is a modified unity gain Sallen-Key.
But with the feedback (for the filter moved) gain resistors added
and a capacitor added to roll-off the gain at very low frequencies.
(This reduces output DC offset)
Are you going full range or 2-way ?
Usually you need 2-way for a really good miniature bass unit.
What sort of amplifier power are we talking about ?
What speaker volume (internal) are you going for ?
Note in small speakers the cabinet has a surpringly large
percentage of the external volume, especially with thick walls.
Ideally with volume an issue you'll need flared ports.
You don't want frequency to be adjustable, it must match port tuning.
Making the Q adjustable is certainly a reasonable possibility.
🙂/sreten.
reread the other thread. CEU's circuit is a modified unity gain Sallen-Key.
But with the feedback (for the filter moved) gain resistors added
and a capacitor added to roll-off the gain at very low frequencies.
(This reduces output DC offset)
Are you going full range or 2-way ?
Usually you need 2-way for a really good miniature bass unit.
What sort of amplifier power are we talking about ?
What speaker volume (internal) are you going for ?
Note in small speakers the cabinet has a surpringly large
percentage of the external volume, especially with thick walls.
Ideally with volume an issue you'll need flared ports.
You don't want frequency to be adjustable, it must match port tuning.
Making the Q adjustable is certainly a reasonable possibility.
🙂/sreten.
Hi again,
I rather thought that a dual tuning capacitor would be nice, because it's not easy to adapt that filter's parts to your specifical needs with the normally available capacitor values. And if I change the resistors to finetune the frequency, the q also changes, so I'll have to fiddle around 🙂
But if the port and filter frequency are near, but not identical, the boost is pretty much the same (at least it looks that way in WinISD)
The rest of the project is not a problem anymore.
This will be my first self-built speakers, so I want to keep it simple. One wideband chassis, 3,5l to 4l volume.
Amplifier: First, this was intended to take away with me.. to the beach, on vacations... with a tiny Class-D amp (battery powered), but possibly I'm building this with a small 8 to 20W amp for a small room. Would be cute I think and the intention is to make it sound bigger, but still clean, hopefully.
Now, I'll look for what a "flared port" is.
Cheers,
Dominique
I rather thought that a dual tuning capacitor would be nice, because it's not easy to adapt that filter's parts to your specifical needs with the normally available capacitor values. And if I change the resistors to finetune the frequency, the q also changes, so I'll have to fiddle around 🙂
But if the port and filter frequency are near, but not identical, the boost is pretty much the same (at least it looks that way in WinISD)
The rest of the project is not a problem anymore.
This will be my first self-built speakers, so I want to keep it simple. One wideband chassis, 3,5l to 4l volume.
Amplifier: First, this was intended to take away with me.. to the beach, on vacations... with a tiny Class-D amp (battery powered), but possibly I'm building this with a small 8 to 20W amp for a small room. Would be cute I think and the intention is to make it sound bigger, but still clean, hopefully.
Now, I'll look for what a "flared port" is.
Cheers,
Dominique
Oh yes, I saw those trumpets 🙂 already and wanted to use one anyway!
http://www.users.bigpond.com/bcolliso/port-flares.htm
and
http://www.users.bigpond.com/bcolliso/flares-25mm.htm
contain nice infos.
Best wishes,
Dominique
http://www.users.bigpond.com/bcolliso/port-flares.htm
and
http://www.users.bigpond.com/bcolliso/flares-25mm.htm
contain nice infos.
Best wishes,
Dominique
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