My local carpenter built me some wooden grills with a cloth over it. They just "hang" on the frame, and are removed when music is playing...
I was too scared to leave them naked and exposed... (Even though magnet is on the back of the speaker, it attracts kids fingers, usually through the dustcap...)
More pics...
I was too scared to leave them naked and exposed... (Even though magnet is on the back of the speaker, it attracts kids fingers, usually through the dustcap...)
More pics...
Attachments
panomaniac said:
Thanks. That was also the WAF prerequisite in order for them to be allowed in the living room. 😎
Hollow sound !
I've rigged up my OB and it doesn't sound magical like it did when I used planar drivers !
APT-80 , Alpha8A and Delta15A ( not connected right now ) on a 450x900 mm baffle.
The sound is hollow and HF isn't as nice as my stock Mission 701 speakers . Very disapopointed !
The APT is crossed over at 18db/octave at about 4Khz and Alpha by a 1st order at about 4Khz. Maybe I'll need a 12db filter.
There is a hollowness to the voice . I didn't notice this when I drove the Alpha wide band. I must admit that I'm crying without looking into the problem!
I must be doing something wrong because the crossover was installed at 12 midnight and today I don't have much time to look into it.
BUT the potential to beat the Mission seems to be there. Wonder if the Alpha6 is a better driver ?
I've rigged up my OB and it doesn't sound magical like it did when I used planar drivers !
APT-80 , Alpha8A and Delta15A ( not connected right now ) on a 450x900 mm baffle.
The sound is hollow and HF isn't as nice as my stock Mission 701 speakers . Very disapopointed !
The APT is crossed over at 18db/octave at about 4Khz and Alpha by a 1st order at about 4Khz. Maybe I'll need a 12db filter.
There is a hollowness to the voice . I didn't notice this when I drove the Alpha wide band. I must admit that I'm crying without looking into the problem!
I must be doing something wrong because the crossover was installed at 12 midnight and today I don't have much time to look into it.
BUT the potential to beat the Mission seems to be there. Wonder if the Alpha6 is a better driver ?
Re: Hollow sound !
try with just high pass xover on alpha 8 , and then just cap in line with APT
dunno ......... I'm biased ...........
ashok said:
try with just high pass xover on alpha 8 , and then just cap in line with APT
dunno ......... I'm biased ...........
Hi ashok.
I have come to this thread for the first time today and see you report problems blending in the APT.
Unfortunately the thread is too long for me to go back and check all the details that have gone before.
4kHz on the 8A. Try running direct with a piece of 1.5" dia light foam sponge (roller or carwash) ahead and just clear of, thus covering the lower half of the dust-cap as seen from the listening position. This will disperse/filter some of the 8A peak prior to roll-off without affecting the electrical input to the driver.
18dB/oct 4kHz on the APT - this likely means you are using an inductor - which stores energy - which can colour reproduction. Also, the APT80 is louder circa 4kHz than above 10kHz, so the 'SPL' crossover is not matching the electrical crossover. I would suggest that the electrical crossover needs to be higher to acheive an SPL balance.
Notably, an APT benefits from parallel resistor electrical damping when driven by a crossover which presents high impedance at low treble frequecies.
Connect say a 15 ohm resistor across the APT terminals then try a simple single 1.0uF in series with the APT with '+' to '+' phase connection. The front of the APT magnet would also need to be roughly level with the edge of the 8A cone dustcap.
Then try changing the value of the damping resistor between say 6.8 and 22 ohm, and the capacitor value between say 0.47 and 2.2uF. Not only does the resistor in parallel with the APT damp the voice coil, it also reduces the excess sensitivity in the crossover region, and via the crossover capacitor acts as a Zobel for the 8A where its impedance rises considerably.
Additionally you might care to try a resistor in series with the capacitor if the tweeter output remains too high.
I would also recommend making these changes when listening from normal room positions by having a separate wire coming to you and then back to the tweeter. Once you are satisfied that you have achieved the best compromise possible you can wire directly and take any fine adjustments forwards from there.
I suggest this will get rid of the hollowness on voice, and give you a chance to adjust reproduction to your own requirement.
After all this you might then want to try a 12 or 18 dB/oct arrangement; armed with this kind of experience, and having baffle pairs means you can check one against another with mono drive.
Cheers .......... Graham.
An example of foam response shaping is photographed below; here on an 8" Visaton B200.
I have come to this thread for the first time today and see you report problems blending in the APT.
Unfortunately the thread is too long for me to go back and check all the details that have gone before.
4kHz on the 8A. Try running direct with a piece of 1.5" dia light foam sponge (roller or carwash) ahead and just clear of, thus covering the lower half of the dust-cap as seen from the listening position. This will disperse/filter some of the 8A peak prior to roll-off without affecting the electrical input to the driver.
18dB/oct 4kHz on the APT - this likely means you are using an inductor - which stores energy - which can colour reproduction. Also, the APT80 is louder circa 4kHz than above 10kHz, so the 'SPL' crossover is not matching the electrical crossover. I would suggest that the electrical crossover needs to be higher to acheive an SPL balance.
Notably, an APT benefits from parallel resistor electrical damping when driven by a crossover which presents high impedance at low treble frequecies.
Connect say a 15 ohm resistor across the APT terminals then try a simple single 1.0uF in series with the APT with '+' to '+' phase connection. The front of the APT magnet would also need to be roughly level with the edge of the 8A cone dustcap.
Then try changing the value of the damping resistor between say 6.8 and 22 ohm, and the capacitor value between say 0.47 and 2.2uF. Not only does the resistor in parallel with the APT damp the voice coil, it also reduces the excess sensitivity in the crossover region, and via the crossover capacitor acts as a Zobel for the 8A where its impedance rises considerably.
Additionally you might care to try a resistor in series with the capacitor if the tweeter output remains too high.
I would also recommend making these changes when listening from normal room positions by having a separate wire coming to you and then back to the tweeter. Once you are satisfied that you have achieved the best compromise possible you can wire directly and take any fine adjustments forwards from there.
I suggest this will get rid of the hollowness on voice, and give you a chance to adjust reproduction to your own requirement.
After all this you might then want to try a 12 or 18 dB/oct arrangement; armed with this kind of experience, and having baffle pairs means you can check one against another with mono drive.
Cheers .......... Graham.
An example of foam response shaping is photographed below; here on an 8" Visaton B200.
Attachments
I measured the OB speaker response and found the tweeter was way too low. So I altered the attenuation to about -5db from -10db and the APT80 seemed to match up with the Alpha8A.
Now the sound (from one channel only).
The Mission is smoother in the voice but overall it sounds 'mushy' in comparison to the OB. This was a shock. Bass is deep from the Mission but sounds like walking on very wet clay ! If you know what I mean.
The OB is certainly much more up front in the midrange and as the bass driver is not connected right now ,it's surprising what it's doing. AND it can go really loud ! But I can see that it will need LOTS of tweaking to get it just right. It's obvious that the Mission will eventually loose out by miles.
While the OB is promising right now , it isn't yet a 'good sounding' system.
The APT-80's don't seem to be very similar. One driver's response goes out to 20 Khz. The other drops like a stone after about 15Khz !Is that really within the production spread ?
Cheers.
Now the sound (from one channel only).
The Mission is smoother in the voice but overall it sounds 'mushy' in comparison to the OB. This was a shock. Bass is deep from the Mission but sounds like walking on very wet clay ! If you know what I mean.
The OB is certainly much more up front in the midrange and as the bass driver is not connected right now ,it's surprising what it's doing. AND it can go really loud ! But I can see that it will need LOTS of tweaking to get it just right. It's obvious that the Mission will eventually loose out by miles.
While the OB is promising right now , it isn't yet a 'good sounding' system.
The APT-80's don't seem to be very similar. One driver's response goes out to 20 Khz. The other drops like a stone after about 15Khz !Is that really within the production spread ?
Cheers.
Hi,
Just one "dumb" question:
Has anyone tried to cut off the dustcap out of Eminence Beta 15, (or Alpha 15), and install a phase plug? Any noticeable change of the sonic presentation in the bass?
Thanks
Vix
Just one "dumb" question:
Has anyone tried to cut off the dustcap out of Eminence Beta 15, (or Alpha 15), and install a phase plug? Any noticeable change of the sonic presentation in the bass?
Thanks
Vix
Today I tried a phase plug on the Alpha-8A on which I had removed the dust cap. It does sound different. Now I'm not sure what is different but it sounds more laid back !😱
The transients seem to lack the energy it had before. I must confess I don't quite remember what amp I had used before . There are four of them here right now. I will have to check each one of them.
My plug is a paper multi layer roll with a plaster of paris front. Will put up pics tomorrow.
Interesting experiment. I couldn't take of the plug in a hurry to check the difference as it was still soft and I was afraid it would collapse if I tried to pull it out in a hurry. It should be dry by tomorrow !
Taking the dust cap off the Delta might increase it's compliance and reduce resonance frequency . I guess Qts will change also.
Will move towards being more floppy ! But then it should help with an OB I think. however I'm not quite sure if the result will be so audible.
Cheers.
The transients seem to lack the energy it had before. I must confess I don't quite remember what amp I had used before . There are four of them here right now. I will have to check each one of them.
My plug is a paper multi layer roll with a plaster of paris front. Will put up pics tomorrow.
Interesting experiment. I couldn't take of the plug in a hurry to check the difference as it was still soft and I was afraid it would collapse if I tried to pull it out in a hurry. It should be dry by tomorrow !
Taking the dust cap off the Delta might increase it's compliance and reduce resonance frequency . I guess Qts will change also.
Will move towards being more floppy ! But then it should help with an OB I think. however I'm not quite sure if the result will be so audible.
Cheers.
I think the major issue with dustcabs is that they mostly are glued to the cone far away from voicecoil, leaving a rather big ressonant chamber behind it
Furthermore vibrations are traveling across the dustcab from one side of cone to the other...that is bound to create phase and distortion problems
A dustcab should be glued to the voicecoil and nowhere else
At the moment I am using foamplugs instead, and it seems to work ok
Another issue may be that on some cheaper drivers with thin cone, the dustcab is also used to strengthen the wobley cone, which means that when dustcab is removed the cone may need som other treatment to strengthen it
Nothing wrong with a good shaped dustcab when mounted correctly...but it may be benefitial with some coating on the dustcab, at least...kills ressonance arround the voicecoil
Furthermore vibrations are traveling across the dustcab from one side of cone to the other...that is bound to create phase and distortion problems
A dustcab should be glued to the voicecoil and nowhere else
At the moment I am using foamplugs instead, and it seems to work ok
Another issue may be that on some cheaper drivers with thin cone, the dustcab is also used to strengthen the wobley cone, which means that when dustcab is removed the cone may need som other treatment to strengthen it
Nothing wrong with a good shaped dustcab when mounted correctly...but it may be benefitial with some coating on the dustcab, at least...kills ressonance arround the voicecoil
I have met PHL owner and chief engineer Philippe Lesage once at Pro Light & Sound, and he has told me that a proper dust cap stiffens the cone considerably and lessens distortion. He is using carbon fiber dust caps.
PHL AUDIO was founded in 1990 by Philippe LESAGE, after he had spent12 years in loudspeaker development at AUDAX industries as head of the R&D Department.
PHL AUDIO was founded in 1990 by Philippe LESAGE, after he had spent12 years in loudspeaker development at AUDAX industries as head of the R&D Department.
Vix said:
Bass wave lengths wouldn't "see" a phase plug due to their size. I take it that you weren't considering running it into the midrange.
Imagine a coated cone with a big dustcab mounted with some distance from the voicecoil...not very hard as there are many, probably most of them
Look at a coated cone, the area behind the dustcab, and you will most likely find that the cone area behind the dustcab is NOT coated...thats not good solid practice to me
Nothing wrong with dustcabs, other than its mostly mounted in the wrong place
Look at a coated cone, the area behind the dustcab, and you will most likely find that the cone area behind the dustcab is NOT coated...thats not good solid practice to me
Nothing wrong with dustcabs, other than its mostly mounted in the wrong place
The Eminence Alphas have proper dustcaps.
the Eminence Magnum series had proper phase plugs, with mesh dustcaps over top of the phase plugs. They were more there for low compression and heat dissipation than controlling cone cancellations.
Phase plug is a great thing for some speakers, not so for others, and a detriment to some. Mostly I'd say it's a desirable feature because there's no trapped air in the gap.
the Eminence Magnum series had proper phase plugs, with mesh dustcaps over top of the phase plugs. They were more there for low compression and heat dissipation than controlling cone cancellations.
Phase plug is a great thing for some speakers, not so for others, and a detriment to some. Mostly I'd say it's a desirable feature because there's no trapped air in the gap.
pedroskova said:
Thanks.
In some cases (like Yunick's) OB's where only 1st order LP filter is used (at approx. 150 Hz) it seems that there is also some midrange coming out of the bass speaker. Of course it could be remedied by a Zobel, or a 2nd or 3rd order filter.
But I was wondering if some of this "midrange" was caused by Eminence Beta 15's rising response, and if this could be actually lessend by cutting a dustcap and installing a phase plug... (thus getting better sound only with the 1st order LP)
Vix
The Alpha-6A seems to have it's dust cap on the coil former unlike the Alpha 8A which has a dust cap higher up the cone.
So from what is being said , the Alpha 6A might sound better as it has less space under the cap for any resonance ? I'm assuming that both cones sound good by themselves. The frequency response certainly looks flatter on the Alpha6A ( published curve).
So from what is being said , the Alpha 6A might sound better as it has less space under the cap for any resonance ? I'm assuming that both cones sound good by themselves. The frequency response certainly looks flatter on the Alpha6A ( published curve).
Just wanted to thank hakunin for post #333.. lots of good info there! I had been looking for non-published graphs on all these drivers from someone else besides Eminence, especially the Alpha-6A.. Don't see the Alpha 8, but the Beta 8 is there. APT80 too. And a ton of other stuff. 😀
http://prodance.cz/protokoly.php?AnchorID=49&Lng=EN (for anyone who missed it)
Thanks again. 🙂
http://prodance.cz/protokoly.php?AnchorID=49&Lng=EN (for anyone who missed it)
Thanks again. 🙂
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