Re: Something to consider
The mid grill is contoured to the driver so it was much easier just to remove the driver and fill the hole. I believe this deviation is still in step with your suggestion.
It does show there are a couple db to be re-gained.
Also I would like to mention I have spent some time re-reading Claudio’s guide on Speaker Workshop. I have tried all manner of things to get the start gate closer to the pulse and get good measurements but not much luck. The only thing that worked is if I took measurements at .5 meter. But the dip was still measuring the same regardless.
dlr said:I've measured more than 2db of diffraction in some instances, the worse being a hard coned midwoofer, the Accuton C95. Put a flat cover, cardboard should do fine, over the nearest driver (and successive ones if you wish) and re-measure taking care not to damage the surrounds. You may be surprised at just how much is related to adjacent drivers. I'm curious to see the difference.
The mid grill is contoured to the driver so it was much easier just to remove the driver and fill the hole. I believe this deviation is still in step with your suggestion.
An externally hosted image should be here but it was not working when we last tested it.
It does show there are a couple db to be re-gained.
Also I would like to mention I have spent some time re-reading Claudio’s guide on Speaker Workshop. I have tried all manner of things to get the start gate closer to the pulse and get good measurements but not much luck. The only thing that worked is if I took measurements at .5 meter. But the dip was still measuring the same regardless.
worth trying ...
I wonder if it would be worth purchasing an inexpensive dome tweeter like or similar to the one here ...
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=275-030
and mount it up on the cab in place of the C23 using cardboard and see what the results are.
Would be nice if it was a tweeter you guys have experaince with, measurements ...ect.
I wonder if it would be worth purchasing an inexpensive dome tweeter like or similar to the one here ...
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=275-030
and mount it up on the cab in place of the C23 using cardboard and see what the results are.
Would be nice if it was a tweeter you guys have experaince with, measurements ...ect.
DSP_Geek said:
It's a start. Now try cutting right angle triangles from that felt and placing them on the baffle edges, with the 90 degree angle pointing at the tweeter, like so:
Using the cardboard baffle from the previous test?
ttruman said:
Using the cardboard baffle from the previous test?
Sure. Might be fun to try on the real cabinet, too.
ok geek. Here it is.
The other felt tests did not help near the dip so I wasn't expecting much here either. I think what is becoming very obvious after all this testing is that the biggest improvements will come from optimizing the placement of the driver on the baffle.
But I think its better to say:
The solution will be found in optimizing the baffle for the driver.
An externally hosted image should be here but it was not working when we last tested it.
The other felt tests did not help near the dip so I wasn't expecting much here either. I think what is becoming very obvious after all this testing is that the biggest improvements will come from optimizing the placement of the driver on the baffle.
But I think its better to say:
The solution will be found in optimizing the baffle for the driver.
ttruman said:But I think its better to say:
The solution will be found in optimizing the baffle for the driver.
Based on a gut feeling that this tweeter does not like being on a flat baffle, I carved an angular one up using foam (very rough).
An externally hosted image should be here but it was not working when we last tested it.
Bring it to DIY NE
Dave
I see that you're in Springfield. Consider bringing the system to DIY NE here in Canton, probably in October again, the date's not yet set, it'll be on a Saturday. We can take a set of measurements here for comparison.ttruman said:
Based on a gut feeling that this tweeter does not like being on a flat baffle, I carved an angular one up using foam (very rough).
Dave
ttruman said:
Hi Charles,
Thanks for joining in. Here is the results of the off axis...
An externally hosted image should be here but it was not working when we last tested it.
If I am not mistaken this is similar to what Dan (owdi) encountered. I believe this strengthens the baffle diffraction argument?
A sim of the off axis diffraction with the box:
An externally hosted image should be here but it was not working when we last tested it.
...sort of consistent with the differences between the measured curves.
Re: Bring it to DIY NE
Appreciate the invite and the offer. I am sure information about DIY NE will be posted on the site when it becomes available. Where should I look?
dlr said:
I see that you're in Springfield. Consider bringing the system to DIY NE here in Canton, probably in October again, the date's not yet set, it'll be on a Saturday. We can take a set of measurements here for comparison.
Dave
Appreciate the invite and the offer. I am sure information about DIY NE will be posted on the site when it becomes available. Where should I look?
Svante said:A sim of the off axis diffraction with the box:
...sort of consistent with the differences between the measured curves.
It would seem my situation is a bit of an oddity. My measurements have excellent consistency but I question them. In part due to my lack of experience; I have no trusted measurement data to compare against either. I am planning on purchasing an inexpensive tweeter that I can mount in the existing tweeter location. Something used in documented DIY projects. This should help to establish confidence (or not).
On a side note, the foam baffle geometry seems to exhibit the textbook 6db roll off as the wave front wraps around the baffle.
I see that the dip is still there at 15 degrees and still a small depression at 30 degrees. This would increase the chance to perform some type of EQing (it would definitely not be advisible if the measurements had shown a hump off-axis for instance).
EQing could be done the passive way if the tweeter has to be padded down (i.e. if it is more efficient than the midrange or midwoofer they are to paired with).
Maybe this is an option for you since the box looks gorgeous as is.
Regards
Charles
Edit: Or listen to the speaker off-axis form the beginning, SAF is increased by speakers that are not toed - in.
EQing could be done the passive way if the tweeter has to be padded down (i.e. if it is more efficient than the midrange or midwoofer they are to paired with).
Maybe this is an option for you since the box looks gorgeous as is.
Regards
Charles
Edit: Or listen to the speaker off-axis form the beginning, SAF is increased by speakers that are not toed - in.
Re: Re: Bring it to DIY NE
Once the date is set I'll update my web site section found DIY New England.
Dave
I should make inquiries this week on the boards as to interest and date, almost quaranteed to be in October. Due to my wife's schedule it will be either the 6th or the 20th.ttruman said:
Appreciate the invite and the offer. I am sure information about DIY NE will be posted on the site when it becomes available. Where should I look?
Once the date is set I'll update my web site section found DIY New England.
Dave
phase_accurate said:I see that the dip is still there at 15 degrees and still a small depression at 30 degrees. This would increase the chance to perform some type of EQing (it would definitely not be advisible if the measurements had shown a hump off-axis for instance).
EQing could be done the passive way if the tweeter has to be padded down (i.e. if it is more efficient than the midrange or midwoofer they are to paired with).
Maybe this is an option for you since the box looks gorgeous as is.
Regards
Charles
Edit: Or listen to the speaker off-axis form the beginning, SAF is increased by speakers that are not toed - in.
Thanks for the kudos on the box. I will have to consider padding down if I want to avoid modifying the box. However that dip is right where I would like to crossover. Crossing the C96 mid beyond 3K isn't the best solution either. I have tried various cross overs and filters but it's been difficult to tame.
Hi ttruman,
I am facing a similar issue with my speaker. I have an Accuton C292-6 7 inch Mid/Bass and Accuton C223-6 1.2 inch Tweeter. I had built a 2 way sealed box monitor (crossover at 2kHz), but the high frequencies were rolling off at around 9kHz. I am in Boston area, MA; kindly let me know if you get a solution to this problem.
Thanks,
BSSK
I am facing a similar issue with my speaker. I have an Accuton C292-6 7 inch Mid/Bass and Accuton C223-6 1.2 inch Tweeter. I had built a 2 way sealed box monitor (crossover at 2kHz), but the high frequencies were rolling off at around 9kHz. I am in Boston area, MA; kindly let me know if you get a solution to this problem.
Thanks,
BSSK
bssk said:Hi ttruman,
I am facing a similar issue with my speaker. I have an Accuton C292-6 7 inch Mid/Bass and Accuton C223-6 1.2 inch Tweeter. I had built a 2 way sealed box monitor (crossover at 2kHz), but the high frequencies were rolling off at around 9kHz. I am in Boston area, MA; kindly let me know if you get a solution to this problem.
Thanks,
BSSK
Hi BSSK,
No problem. It would be helpful to learn from you as well. I am curious...what do the free air measurements on your C23's look like?
DIY NE will be Oct 20th
I'll update my web pages soon, but not much will change from last year. Info can be found at the link.
DIY New England
Dave
ttruman said:Look forward to it. I'll keep my eyes open.
Tim
I'll update my web pages soon, but not much will change from last year. Info can be found at the link.
DIY New England
Dave
Hi ttruman,
hope your build ended up being a success.
I just realised that the membrane ear cut outs are facing different directions in you photos.
left/right: #29, 50, 51, 60, 61, 65, 66
up/down: #35, 38, 42
I have no idea how this correlates with your measurements though.
Cheers,
Erik
hope your build ended up being a success.
I just realised that the membrane ear cut outs are facing different directions in you photos.
left/right: #29, 50, 51, 60, 61, 65, 66
up/down: #35, 38, 42
I have no idea how this correlates with your measurements though.
Cheers,
Erik
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