What is egg crate style foam? As suggested by Bjorno, perhaps your problem is too much acoustic absorbent in the box. Maybe the foam is severely weakening box resonance and thus giving you a high bass cut-off frequency? You could maybe check to see that you are getting a healthy air flow at the vent.
Regards,
Pete
report
Thanks for your comments people
Here is an update to now
On Thursday I went back to my workshop reassembled the speakers put them on test and found that they needed to be driven harder by my amp
This power increase helped a lot with the output
At one stage of our auditioning the dB meter peaked around 99
These little boxes take way more power than the other speakers that I built so I suppose it is a learning curve for me now
I did record from a meter away and at as best as my analogue power output meters on the amp let me (accuracy) at one watt the tweeter is about 3dB louder than the woofer
This was reflected in the crossover design which I used from the software that I purchased (xover pro)
Some of the comments where that they sounded a little bright
I have taken some photos of the project but it has been that long since posting I have forgotten how to attach the files
Was it through photo bucket?
If someone is kind enough to remind me I will put up the photos and crossover for your consideration
Once I get these boxes sorted I will start to assemble the towers that Mick was talking about
Once again thank you for your helpful input
Cheers speedie
Thanks for your comments people
Here is an update to now
On Thursday I went back to my workshop reassembled the speakers put them on test and found that they needed to be driven harder by my amp
This power increase helped a lot with the output
At one stage of our auditioning the dB meter peaked around 99
These little boxes take way more power than the other speakers that I built so I suppose it is a learning curve for me now
I did record from a meter away and at as best as my analogue power output meters on the amp let me (accuracy) at one watt the tweeter is about 3dB louder than the woofer
This was reflected in the crossover design which I used from the software that I purchased (xover pro)
Some of the comments where that they sounded a little bright
I have taken some photos of the project but it has been that long since posting I have forgotten how to attach the files
Was it through photo bucket?
If someone is kind enough to remind me I will put up the photos and crossover for your consideration
Once I get these boxes sorted I will start to assemble the towers that Mick was talking about
Once again thank you for your helpful input
Cheers speedie
Hi Speedie, click Go Advanced, then manage attachments up upload them. resize them to something reasonable (no bigger than 1024 X 768, I usually do 800 X 600) first. This is the best option as they stay with the forum, lots of people have problems with externally hosted images, or over time the links break etc.
Good that you have an spl meter makes tracking down the issue much easier!
Tony.
Good that you have an spl meter makes tracking down the issue much easier!
Tony.
I really do wonder about the use of that egg-crate foam for damping. This is the first time that I've heard of using it for that purpose. Are you using it based on a recommendation from an authoritative source? It looks like it is fairly dense, in which case it might actually reduce the effective inside volume of your system.
Regards,
Pete
Regards,
Pete
1- Zobel both your tweeter and your woofer.I did record from a meter away and at as best as my analogue power output meters on the amp let me (accuracy) at one watt the tweeter is about 3dB louder than the woofer
This was reflected in the crossover design which I used from the software that I purchased (xover pro)
Some of the comments where that they sounded a little bright
2- Compensate the motional impedance of your tweeter.
3- Attenuate your tweeter by 4dbs between the filter and the zobel + the motion compensation (ascending curve is a miss). Keep the impedance constant to do not change the cutoff of the filter.
4- Remove this foam and use glass-wool panels in the middle of each volume. Never stick the damping material ON the panels.
listening
esperando thanks for the reply
question why never glue foam to panels
is there a sonic signature that this type of foam will yeild negitive results
yesterday i took my speakers to my friends house and coupled them into his system (emotiva xpa2 and cd player) and we were both happy with the results they played clean and clear even when pushed up on the volume level
so my initial comments were not clearly thought through
in hinsight i suppose that when asseccing new things it should be done on quality equpment
not to say that the old gear at my workshop is poor just old
it would be appreciated if you would elaborate on zobels etc
funny thing hifi we seek fidelity in our hearing at the wrong end of our life span
cheers speedie
esperando thanks for the reply
question why never glue foam to panels
is there a sonic signature that this type of foam will yeild negitive results
yesterday i took my speakers to my friends house and coupled them into his system (emotiva xpa2 and cd player) and we were both happy with the results they played clean and clear even when pushed up on the volume level
so my initial comments were not clearly thought through
in hinsight i suppose that when asseccing new things it should be done on quality equpment
not to say that the old gear at my workshop is poor just old
it would be appreciated if you would elaborate on zobels etc
funny thing hifi we seek fidelity in our hearing at the wrong end of our life span
cheers speedie
Yes, there is a sonic signature (differences of damping with frequencies) between material and densities. Less is the best. In the middle between the panels is where the air speed is maximum. So the efficiency in low medium. I'm not sure your foam do not eat too much volume and glass wool is more neutral than foam witch give a dull sound. (seems too compact ?).
Glass wool witch was always used once is forbidden in industry, nowadays. But, if you DIY, (with care for your skin ), you have this luck to use-it again.
If you publish the exact references of your loudspeakers and values of your filters, may-be i can calculate for you Zobel and motional impedance compensation circuits as well as the -3db attenuator values for you tweeter.
Those compensations will give-you a linear impedance curve (best for your amp), better group delay and obvious listening improvement. As they are parallel with the speakers, you can remove them any time to compare.
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Most like the issue is the room you are using them in. Many times you get cancellation in the bass region due to bass reflecting off walls, floor, ceiling, and furniture which creates dead areas in the room. Moving the speakers around may improve that.
Zobels are used to insure that the impedance of the driver, as seen from the crossover, is flat and does not change with frequency. This insures the crossover does what it was designed to do.
This link will help explain this and more.
I would ditch the foam on the cabinet walls and replace it with either fiberglass stuffing or something like Acusta-Stuff. I would apply no more than an inch thick to start with and only cover about 50% of the walls. The back panel directly behind the woofer should have fiberglass on it to absorb the direct rear wave.
I have found that too much fill in a ported cabinet will kill the bass.
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thanks for your reply guys
firstly i have had problems getting my other photos onto the forum
these give a goor view of the crossover construction
unfortunatly i will find it quite difficult to remove the foam as the boxes are all glued seams
having seen foam on studio walls and being in airconditioning where there is similar material used for sound attenuation i assumed that this would be a safe and sound box stuffing
the old stuff that was used for insulation is either rockwool or fibreglass either of which i have bad memories of
i will try and put up the xover pro crossover for your concideration
cheers fellows speedie
firstly i have had problems getting my other photos onto the forum
these give a goor view of the crossover construction
unfortunatly i will find it quite difficult to remove the foam as the boxes are all glued seams
having seen foam on studio walls and being in airconditioning where there is similar material used for sound attenuation i assumed that this would be a safe and sound box stuffing
the old stuff that was used for insulation is either rockwool or fibreglass either of which i have bad memories of
i will try and put up the xover pro crossover for your concideration
cheers fellows speedie
X?over Pro
Hmmm......
Another piece of relatively expensive software that doesn't seem to
take into account baffle effects, i.e. it doesn't do the job properly.
See the guides below, and include the baffles in your modelling.
rgds, sreten.
http://sites.google.com/site/undefinition/diy (see FAQs)
Zaph|Audio
FRD Consortium tools guide
Designing Crossovers with Software Only
RJB Audio Projects
Jay's DIY Loudspeaker Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design
Great free SPICE Emulator : SPICE-Based Analog Simulation Program - TINA-TI - TI Tool Folder
Hmmm......
Another piece of relatively expensive software that doesn't seem to
take into account baffle effects, i.e. it doesn't do the job properly.
See the guides below, and include the baffles in your modelling.
rgds, sreten.
http://sites.google.com/site/undefinition/diy (see FAQs)
Zaph|Audio
FRD Consortium tools guide
Designing Crossovers with Software Only
RJB Audio Projects
Jay's DIY Loudspeaker Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design
Great free SPICE Emulator : SPICE-Based Analog Simulation Program - TINA-TI - TI Tool Folder
Yes, but calculating baffle step does not require software, just a calculator.
F = 115 / W (W is the baffle width in meters)
However, the room itself and speaker placement determines how much of a "step" you realize. Then there is room gain...
Neither of those will be addressed in any software.
I don't know where his crossover point really is, but if the cabinet is 150mm wide, then the F3 point is about 750 Hz.
That is probably well below the actual crossover point, so leveraging that is probably out of the question.
What's the hell to remove most of the foam ? It is not hard as Diamond. But if the boes are yet glued, yes, forget about-it. Foam is used even in anechoic chamber, (together with fiberglass) for obvious reasons, but i swear (designed, measured, and build hundreds of enclosures) that it sound less good as what i indicate: soft fiberglass glued in cross in the middle between the panels in the 3 dimensions. If you are about re-calculating your filters, remember that, in treble, and even if the two speakers are in phase at this frequency, you have to reduce the crossover at -3db instead of -6db, because there is no more acoustic coupling between the loudspeakers.
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Hi,
That is far too simplistic for a quality design.
Model it, or measure it, or both. Zaphs SR71 baffle diffraction sim.
rgds, sreten.
Yes, but calculating baffle step does not require software, just a calculator.
F = 115 / W (W is the baffle width in meters)
However, the room itself and speaker placement determines how much of a "step" you realize. Then there is room gain...
Neither of those will be addressed in any software.
I don't know where his crossover point really is, but if the cabinet is 150mm wide, then the F3 point is about 750 Hz.
That is probably well below the actual crossover point, so leveraging that is probably out of the question.
I should add, the link I supplied earlier has all the math and even an Excel spreadsheet for calculating a 2-way crossover circuit. That is all free and you really don't need fancy software.
The benefit of doing this by hand is you learn a lot more than letting some software do it automagically.
F = 115 / W (W is the baffle width in meters)
However, the room itself and speaker placement determines how much of a "step" you realize. Then there is room gain...
Neither of those will be addressed in any software.
I don't know where his crossover point really is, but if the cabinet is 150mm wide, then the F3 point is about 750 Hz.
That is probably well below the actual crossover point, so leveraging that is probably out of the question.
I should add, the link I supplied earlier has all the math and even an Excel spreadsheet for calculating a 2-way crossover circuit. That is all free and you really don't need fancy software.
The benefit of doing this by hand is you learn a lot more than letting some software do it automagically.
Hi,
Repeating yourself doesn't make you any more right, just more wrong.
rgds, sreten.
Hi,
That is far too simplistic for a quality design.
Model it, or measure it, or both. Zaphs SR71 baffle diffraction sim.
rgds, sreten.
Are we throwing the builder into the deep end of the pool?
This is his first build. Baby steps are easier to follow rather than throwing advanced design theory into the build equation.
Like I said before, I am a fan of learning the ropes one step at a time and doing things manually so that the student can understand what is happening under the hood and why.
The point about diffraction is just noise right now. The cabinet has been built and he is not going to relocate the driver position nor should he.
However, learning about diffraction is a good thing. Just not essential at this point. Just my opinion.
Sorry about that, I got the post written and my step son called and was just in an auto accident. I had to step out...
When I returned I did not realized it was posted already and hit send again.
So, not more right or wrong - just an accident.
Hi,
Yes. he has spent lot of money and is disappointed. that is most probably
because something has gone wrong, and I'm fairly sure its an inadequate
crossover design.
If you want something to be right you have to do it all right, baby steps
don't help IMO, they just confuse the matter, as does poor c/o calculators.
The point about diffraction is not just noise, it is fundamental to quality.
Your not understanding what I'm saying. The diffraction model of the
current baffle with the drivers published curves will give box response.
The steps are all detailed in the links I provided and can be followed one by one.
The idea that you won't learn something by going through the modelling
process, is just bizarre, it won't do it for you, you have to work it out
and understand what is going on for meaningful results.
And hopefully realise where something went wrong.
rgds, sreten.
http://72.9.35.76/showthread.php?p=1723018 both tricky drivers ...
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