ROOM is the answer to your questions. Until you find the same bass in front of the speakers as the one behind them the most probable reason is this!
Recently I "designed" bass reflex enclosures for a friend, he helped in the design too. We had all possible characteristics and parameters of the bass drivers measured. Then we entered the data in Bass Box 6 Pro. Then we hit the button "optimum". We even entered actual material thickness (30 mm MDF), and the wadding and stuffing, and actual front panel size in the program and actual reflex pipe diameter.
We even took into the accounts the volume displaced by drivers, crossover and bracing...
We even brought the schematics with values of the crossover together with all drivers to acoustics and electronic engineers to check and double check... they checked and double checked and gave green light...
Then we did EXACTLY what was prescribed by the program with great accuracy and care.
We used a known 800-4000 hz crossover and the same bass, midrange and treble drivers it was constructed for.
The end result were a healthy and heavy 128 L net internal volume, thick wall, braced three way bass reflexes which by all laws of nature should reproduce 30 hz @ - 6db.
My friend brought them at home, installed them, played some music through them and then he got into a state of mind which is best described as melancholic depression with suicidal deviation.
No bass!
There was no bass coming out of his bloody speakers! Great midrange and treble, briliant soundstage, detail, you call it they have it... Bass - NO, not at all!
I went to his place thinking that he is either deaf or nuts not to hear bass from a 12 inch driver that has under 30 hz resonance in almost 130 L tuned to ~30hz...
Well, there was no bass indeed! I almost died out of shame! After all I got him into all the trouble in first place... and believe me this was his first technical DIY anything in life! And it took him about two weeks half to full working day to complete the bloody bass lacking speakers and almost divorced...
After some inspections and investigation I found out that there actually was bass coming out of the speakers. Only it was nowhere to be found in the ordinary places to seek bass!
It was behind the speakers and on angles greater than ~60 degrees from one certain cross section of the room.
Tragically the only possible location for the speakers was facing in parallel with this particular cross section.
His living room has irregular shape in the bad acoustical meaning of the word.
Then we brought the speakers to my listening roomThe bass was great... Not only it was there, it was what one should expect after clicking the "optimum" button without arguing with the program and while he has entered a 100% verified data into the software... and... while he has done all specified above.
We brought the speakers to the place of another friend who's room is known to be good or at least neutral - again great sounding speakers...
Now my friend has a pair of 5 inch 2 way speakers and a sub in his living room and is uberly happy... Thankfully he didn't have to throw the speakers we made into the fireplace, they will be the first acoustic weapon of his coffee shop that is soon to open
So a nasty room can get you in some real adventures...
By the way check the woofer polarity, but I doubt it is it. And not only check it, but try with reverse polarity. - again I doubt it would help.
See the main characters of this story in post 11 and 12 here: http://www.diyaudio.com/forums/multi-way/179055-sealed-volume-2x12-tb-2.html
Wish you luck! And don't hurry to open yourself undue work!
Thank you so much for this post.
I think the problem is the room I am testing speakers is small10' x 10' , considering the towers.
I am going to make it front port to find the difference, I have not added any damping material as of now.
what I am lacking now is crossover, Right now which I am having is in adequate, I am trying Xover pro.
If you can guide in any ways I am happy.
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From what I see you have a two, maximum 2.5 way speakers.
Two identical woofers and a tweeter.
They are mounted D'Apolito, which is good for the directivity and focus of the speakers.
You can make a two way crossover or a 2.5 way.
The 2.5 way has the same number of parts as a 3 way, but instead of every speaker covering it's own separate frequency band, the two woofers work together in the lowest frequencies, one woofer is cut off as low as possible and the other goes up to the crossover point with the tweeter.
This is for you to read:
http://www.diyaudio.com/forums/multi-way/126456-2-5-way-crossover-design.html
... And I must thank you for your... questions, because you got me curious about whether there was a 2.5 way crossover calculator... and I found it:
Loudspeaker Design Software
Enjoy! Now going to see what I just downloaded from the last link!
Two identical woofers and a tweeter.
They are mounted D'Apolito, which is good for the directivity and focus of the speakers.
You can make a two way crossover or a 2.5 way.
The 2.5 way has the same number of parts as a 3 way, but instead of every speaker covering it's own separate frequency band, the two woofers work together in the lowest frequencies, one woofer is cut off as low as possible and the other goes up to the crossover point with the tweeter.
This is for you to read:
http://www.diyaudio.com/forums/multi-way/126456-2-5-way-crossover-design.html
... And I must thank you for your... questions, because you got me curious about whether there was a 2.5 way crossover calculator... and I found it:
Loudspeaker Design Software
Enjoy! Now going to see what I just downloaded from the last link!
The drivers I have are 8"woofers, not mid bass. I had read midrange drivers need to be fast, Bigger drivers cannot match the speed.
Running these in 2.5 way , Will it need any changes to box volume.
I was thinking of changing the baffle to make it a proper 3 way, and add a 5 1/4 " driver for midrange. Midrange in sealed enclosure, Woofers vented.
I am trying to make them sound as natural as possible without any colourisation.
Did you check the image I posted.
Come on! Be serious! I just found it, it is written above.
If the posted circuit is your actual circuit, then you might want to remove C3, C4 and L2, thus effectively transforming your speakers into 2.5 way.
What make and model are your bass drivers? Any data (parameters) that is known for them would be useful.
With this intervention the bass should double.
Note that you could do this safely only if the bass drivers are 8 ohm or more ones! If they are less than 8 ohms, there is a danger for the amplifier.
The posted circuit is not my actual circuit. I told about changing the baffle to make a proper 3 way, So was modelling crossover for this.
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Crossover is smeared with hardener, Will damage coils if tried to remove.
Going for a completely new crossover will be better.
Hi viki,
Looks OK if 2 drivers are used in a 2-way but if a 3-way and if you really want to predict your box behavior more trustworthy: You need to step away from rookie programs
like WinISD, BassBox Pro... and other lookalikes.b
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Hi viki,
Looks OK if 2 drivers are used in a 2-way but if a 3-way and if you really want to predict your box behavior more trustworthy: You need to step away from rookie programs
b
Hello,
I want to ask what are all the calculations you have made,My speakers are not transmission line, but bass reflex.
I do not possess enough knowledge about box and crossover designing and the factors involved in proper designing. have modeled them in bass box pro and x over pro.
You have made calculation considering floor reflections and many more, what exactly do they stand for and how are those calculations done .
If possible is there a way I can understand step by step process you have undertaken. and the way I should be goping about designing these stuff
Thank you.
Hi,
Transmission line = TL modeled ,No!..You may call your design a bass-reflex if this is what you want/suits you.
So discard the header if you want: Its misleading those who are newcomer to this type of designs ...but Educate yourself : Visit:
Quarter Wavelength Loudspeaker Design
...where you will find out that if extruded(tall) enclosures like yours are to be correctly modeled when using internally damping materials:
The modeling program must then be able to deal with the upcoming quarter-wave issues associated with you type of enclosure and really take the physical airways into consideration, the dimensions of your box.
Of course your design is some sort of transmission-line in that sense.
The program I used is almost suitable for any kind of ported enclosures...
b
Transmission line = TL modeled ,No!..You may call your design a bass-reflex if this is what you want/suits you.
So discard the header if you want: Its misleading those who are newcomer to this type of designs ...but Educate yourself : Visit:
Quarter Wavelength Loudspeaker Design
...where you will find out that if extruded(tall) enclosures like yours are to be correctly modeled when using internally damping materials:
The modeling program must then be able to deal with the upcoming quarter-wave issues associated with you type of enclosure and really take the physical airways into consideration, the dimensions of your box.
Of course your design is some sort of transmission-line in that sense.
The program I used is almost suitable for any kind of ported enclosures...
b
Hi,
Transmission line = TL modeled ,No!..You may call your design a bass-reflex if this is what you want/suits you.
So discard the header if you want: Its misleading those who are newcomer to this type of designs ...but Educate yourself : Visit:
Quarter Wavelength Loudspeaker Design
...where you will find out that if extruded(tall) enclosures like yours are to be correctly modeled when using internally damping materials:
The modeling program must then be able to deal with the upcoming quarter-wave issues associated with you type of enclosure and really take the physical airways into consideration, the dimensions of your box.
Of course your design is some sort of transmission-line in that sense.
The program I used is almost suitable for any kind of ported enclosures...
b
Hello,
How to calculate BSC. And is there any formula or theory to find out the amount of damping material needed.
can I ask you a favor.
Can you guide me to step by step practical procedure, for modelling the box and crossover properly.
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Hi,
Use this calculator to find out the baffle step compensation for your T+2x(M)W driver enclosure:
Home of the Edge
The best suggestion involving a minimum effort would be to convert your design into a 2.5 XO:ed Speaker.
Baffle step compensation can then completely be avoided + a good vertical dispersion can be attained too:
Download the advised Xdir program here below and simulate a 2-way speaker (Your tweeter= T driver + the lower or upper Bass driver = M+W), the upper or lower would then only cover W duties in parallel or series with the M+W driver depending on how your XO is configured.
The inter-driver C-C distance looks to be about 15.5cm?
When you are simulating an ported enclosure using a free box calculator the program suggest you to pick a 'fill' value in % or: Ql ( box leakage loss);Qa(box loss due to damping materials) and Qp((port loss) that if summed equals the Qb(box total loss) values that have to be chosen in prior to finish a simulation run.
This would work well when designing simple enclosures when the box dimensions only endorses a Helmholtz resonance but not when quarter waves are involved where the amount of and placement of damping material have a profound influence on the resulting estimation of the box system FR.
The only way to get around this is to take a iterative step by step approach:
Estimate the box using a box calculator, measure the FR,adjust the box fillings and measure again until an acceptable result is achieved.
This may be the only available approach a DIYer can trust, if he is not equipped with a more advanced simulation programs like MJK's software or the AKAbak program.
This is DIY isn't it: Spoon-feeding is not the right way in aiding designs of complex speaker enclosures espessially when the suggested speaker enclosures are already built.
At a first glance your physical speaker design leaves a lot to discuss...
First: How to rescue the speaker to get proper vertical dispersion characteristics.
I estimate the W C-C distance to be about 32 cm = a large distance for a M-T-M speaker when probably using a tweeter estimated only to be operated above at min ~2 kHz.
Use Svante's Xdir program to get a visual wiev of vertical dispersion of your MTM:
Xdir
See example picture :
b
PS: You've already got the information of the required damping material = both the density and weight.
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Hello,
i was thinking when building a active sub woofer, which design to be better.
have seen vented bass reflex box, But no experience with band pass Design.
How would 4th order bandpass design behave with single 10" driver or 2 8" drivers.
Any advantage over bass reflex designs.
what about Horn loaded design for sub woofer, May be 2 8 inch woofers.
i was thinking when building a active sub woofer, which design to be better.
have seen vented bass reflex box, But no experience with band pass Design.
How would 4th order bandpass design behave with single 10" driver or 2 8" drivers.
Any advantage over bass reflex designs.
what about Horn loaded design for sub woofer, May be 2 8 inch woofers.
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Viki,
I agree with Pinkmouse...Subwoofer:To be used with what? If with your uncompleted MTM? If not:
I recommend You starting a new thread at the Subwoofers forum,
I think you've have already reached the bottom of this fish pond.If you don't place more specific questions/requirements in this thread,don't expect any answers: Your hook is being without a proper bait, at least respond to the already given questions/answers.
b
PS: Did you ever consider to test T101:s good suggestion of converting your filters into a 2.5 filter types and to line a third of the ML-TL enclosure(starting from the top of your enclosure) with damping material?
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