Long time ago I bought some Eminence coaxials and compression drivers including Beta 12CX/ASD1001 and Beta 10CX/APT50 combos. Since then I have been building various cabinets in ply and pine and trying to assemble crossovers for them until I last year decided to buy a pair of pre-assembled PXB2:2K5CX allegedly designed for these combos since my home made crossovers had serious issues and I got tired of having a unfinished project. Ive managed to put together one pair of monitors with 12CX/ASD1001 + PXB2:2K5CX which I am very happy with both the box and the sound. The Beta 10CX and APT50 are spares for future project, more about that later.
I am now curious to know if it is possible to improve the sound without drastic measures? The sound is large, warm, dynamic and for the most part just how I like it with a few exceptions. The midrange area around 2kHz is a bit muddy and uneven I am sure this is because A) the bass have ugly peaks around this area and should be crossed lower than 2,5kHz, and B) the HF driver doesn't really have much volume in this area and it is recommended to cut of at 2,5kHz, and possible C) some baffle resonance issues or other box problems.
Another problem is that the HF L-Pad in the crossover seems a bit too much given the higher sensitivity in the 12" compared to the 10" which I believe was the original aim for the crossover. Some of the highest frequencies seems at least a little bit missing but that may be the rolloff of the driver rather than the LPad.
I have read a lot of threads and see various options, changing crossover and HF drivers seems to be the most common solution and this is no problem for me as I want to use the ASD1001 and the PXB2:2K5CX on the 10" instead, and use the APT50 for another 3-way future project. Yes a lot of projects in my mind.
I have narroved it down to considering the following parts:
HF drivers:
Eminence PSD2002 106dB rec. xo. 1,2kHz
Eminence PSD2013 108dB rec. xo. 1,5kHz
JBL/Selenium D220Ti 109dB rec. xo.1,5kHz
PRV Audio D280Ti-S 109dB rec. xo.1,8kHz
Crossover parts:
Eminence PXB2:1K6 1,6kHz LF12/HF18 no l-pad
Eminence PX-LPAD variable-10dB
Are there other options I should consider?
I see the new KP3012CX 12" coax have a much smoother rolloff so that may also be an option but I feel then its a fully new project new box much higher cost etc.
I am now curious to know if it is possible to improve the sound without drastic measures? The sound is large, warm, dynamic and for the most part just how I like it with a few exceptions. The midrange area around 2kHz is a bit muddy and uneven I am sure this is because A) the bass have ugly peaks around this area and should be crossed lower than 2,5kHz, and B) the HF driver doesn't really have much volume in this area and it is recommended to cut of at 2,5kHz, and possible C) some baffle resonance issues or other box problems.
Another problem is that the HF L-Pad in the crossover seems a bit too much given the higher sensitivity in the 12" compared to the 10" which I believe was the original aim for the crossover. Some of the highest frequencies seems at least a little bit missing but that may be the rolloff of the driver rather than the LPad.
I have read a lot of threads and see various options, changing crossover and HF drivers seems to be the most common solution and this is no problem for me as I want to use the ASD1001 and the PXB2:2K5CX on the 10" instead, and use the APT50 for another 3-way future project. Yes a lot of projects in my mind.
I have narroved it down to considering the following parts:
HF drivers:
Eminence PSD2002 106dB rec. xo. 1,2kHz
Eminence PSD2013 108dB rec. xo. 1,5kHz
JBL/Selenium D220Ti 109dB rec. xo.1,5kHz
PRV Audio D280Ti-S 109dB rec. xo.1,8kHz
Crossover parts:
Eminence PXB2:1K6 1,6kHz LF12/HF18 no l-pad
Eminence PX-LPAD variable-10dB
Are there other options I should consider?
I see the new KP3012CX 12" coax have a much smoother rolloff so that may also be an option but I feel then its a fully new project new box much higher cost etc.
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It really requires measurements to tell what is the problem and how to solve it. Without, it is a guessing game. Do you have a microphone, sound card etc.?
Primary things to measure are:
Other thoughts:
Primary things to measure are:
- Frequency response, time gated, at 0-15-30-60 deg off axis
- Frequency response, ungated, at listening position
Other thoughts:
- The woofer's voice coil protrudes in the high frequency driver's 'horn'. See attached image (taken from http://cognitivevent.com/images/he12_vctrim_500.jpg). You could trim it. It might result in a small improvement at high frequencies.
- A 2.5 kHz crossover frequency is likely to result in a mismatch in directivity between the woofer and HF driver. The woofer already beams at 2.5 kHz, while the HF driver still has a wide dispersion. It would be better to lower it to 1 kHz, assuming the system will only play at moderate Hi-Fi sound pressure levels. Many reasonably prices HF drivers can handle a 1 kHz crossover at Hi-Fi sound pressure levels. If you are okay with taking the chance that you blow the ASD1001's, I would keep using them.
- Off-the-shelf crossovers are no good, they must be designed for your exact drivers only. The easiest and maybe even the cheapest way to design a crossover yourself, is to buy a measurement microphone and implement the crossover on a DSP.
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![he12_vctrim_500[1].jpg](/community/data/attachments/792/792963-e5f23154a0837116c4cab9a1dccbe80d.jpg)
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I'm not going to trim the horn, but does the horn in the coax allow going as low as 1kHz by default? PSD2002 seems to go this low that seems like a good idea for replacement. Measuring is something I try to avoid as its a lot of hassle especially since Ive struggled so much with crossovers before I hope to get somewhat OK results with pre-assembled, Im hoping I just need to find a good match of drivers and crossover and play around with polarity and variable lpad. Im quite happy with how it is today but it would be nice to try another HF drives as I plan to use this current one for the 10" instead.
Emerald Physics has used this coax with a 1 kHz crossover frequency, in their older models. They used a Selenium DT220Ti-8 compression driver.
Model CS 2.3: 6moons audio reviews: Spatial/Emerald Physics System Review
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Why not use an established good deign? (Eminence 10CX with Selenium D220ti)
Osprey-II Revisited (Eminence 10CX with Selenium D220ti) – AmpsLab
I'm not sure the APT-50 is rugged enough for a 10CX:
And eminence PXB2:2K5CX filters are quite basic:
I am sure Michael's design is better. You asked for better crosssover. Well, there it is.
Osprey-II Revisited (Eminence 10CX with Selenium D220ti) – AmpsLab
I'm not sure the APT-50 is rugged enough for a 10CX:
And eminence PXB2:2K5CX filters are quite basic:
I am sure Michael's design is better. You asked for better crosssover. Well, there it is.
the old APT50 is fine at higher xover Fs. Eminence's generic 3K5 board''s highpass gave a corner around 2K8. I'm not sure if the newest APT50 is like the first one - any word?
I don't like the stressful sound of some CD run below 2K on some coax.
Mike Chua is one to ask for sure about EM CX and CD - not sure if he's worked with Beta12cx.
FWIW and mostly likely not correct interpretation, I got more coherent sound with my Eminence C12CX by using an LC LC allpass network on the woofer lowpass.
I used EM's 2K5 cx values for Beta10cx and ADS1001 in my Karlsonator12 - the sound was very bland and would probably grab a FR instead. Mike worked to get Osprey sounding good with vocals. Perhaps its the 2mH lowpass on their board ???
I don't like the stressful sound of some CD run below 2K on some coax.
Mike Chua is one to ask for sure about EM CX and CD - not sure if he's worked with Beta12cx.
FWIW and mostly likely not correct interpretation, I got more coherent sound with my Eminence C12CX by using an LC LC allpass network on the woofer lowpass.
I used EM's 2K5 cx values for Beta10cx and ADS1001 in my Karlsonator12 - the sound was very bland and would probably grab a FR instead. Mike worked to get Osprey sounding good with vocals. Perhaps its the 2mH lowpass on their board ???
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Beta 8CX
I use the Beta 8CX with ASD1001.
The ASD has a very healthy impedance peak that can sound pretty bad with a passive xover (not a problem with active xo). Conjugate completely solves the problem with passive xo.
I get about a 20dB null at xover with polarity reversed, high and very flat input impedance, 96 dB sensitivity, and pretty flat response. And I cannot break them. I use a subwoofer crossed at 40 Hz.
Very pleased.
I use the Beta 8CX with ASD1001.
The ASD has a very healthy impedance peak that can sound pretty bad with a passive xover (not a problem with active xo). Conjugate completely solves the problem with passive xo.
I get about a 20dB null at xover with polarity reversed, high and very flat input impedance, 96 dB sensitivity, and pretty flat response. And I cannot break them. I use a subwoofer crossed at 40 Hz.
Very pleased.
Attachments
And here is my build with Beta12CX and Selenium D210Ti Eminence Beta 12 CX + Selenium D210Ti MLTL (huge)
It includes polar measurements and crossover design.
It includes polar measurements and crossover design.
Steep slopes and lower xo might excessively delay the woofer. Best to use the woofer xo to time align with the tweeter. Coax format inherently aligns woofer and tweeter in the x & y axes. Coordinating delay gets the z axis aligned as well. You can get respectable square wave response without picky mic placement.
This is wrong as a digital crossover can implement pure delay making time alignment easier than an analogue crossover. Furthermore a digital crossover can (within the limitations of its processing) approximate any transfer function synthesized using passive components. At the higher end you also have FIR processing which allows independent phase and amplitude response in filtering that is impossible from passive filters.
This hobby is going to ruin my life, both timewise and moneywise, as it has, on and off, for decades already.
I could not decide so I ordered more or less everything:
Selenium D220Ti
Eminence PSD 2002S
Eminence PXB2 1K6
Eminence PX-LPAD
The plan is then to try to see if one of the two new CDs and the new xo gives any improvement in the B12CX midrange compared to existing ASD1001 and PXB2 2k5CX xo.
If it improves I will use the spare ASD1001 and 2k5 xo on the B10CX and the leftover APT50 in a new 3 way, as well as whichever performs the worst of Selenium and the PSD2002 in B12CX in yet another project.
If not I will start measuring and see if it is at all possible with to go even lower to 1,2kHz in the tiny horn or if I have reached the maximum potential of these coaxials and move on to next project.
Whatever doesn't work I can use in my next projects anyway, its always nice to have lots of parts around, both crossovers and compression drivers it will be fun to play around.
Many projects coming up.
So little time and money yet so much fun with DIY audio.
I could not decide so I ordered more or less everything:
Selenium D220Ti
Eminence PSD 2002S
Eminence PXB2 1K6
Eminence PX-LPAD
The plan is then to try to see if one of the two new CDs and the new xo gives any improvement in the B12CX midrange compared to existing ASD1001 and PXB2 2k5CX xo.
If it improves I will use the spare ASD1001 and 2k5 xo on the B10CX and the leftover APT50 in a new 3 way, as well as whichever performs the worst of Selenium and the PSD2002 in B12CX in yet another project.
If not I will start measuring and see if it is at all possible with to go even lower to 1,2kHz in the tiny horn or if I have reached the maximum potential of these coaxials and move on to next project.
Whatever doesn't work I can use in my next projects anyway, its always nice to have lots of parts around, both crossovers and compression drivers it will be fun to play around.
Many projects coming up.
So little time and money yet so much fun with DIY audio.
A bit late to the 'party', but FWIW: AudioVidioPhilia: Building a pair of Adire HE12.1 Speakers
HE12 Plan's 'Error 404' embedded link is [thankfully] on the net archive: http://web.archive.org/web/20031203150146/http://www.adireaudio.com/Files/HE12-1Plans.pdf
Also, in a PM re any HF driver tweaks such as damping the front chamber, Dan W. noted that it was stuffed with an unspecified amount of either 4/0 alum or stainless steel wool [memory fails and Yahoo mail has deleted all my mail prior to 2004
, though personally have used SS in other brands/models to good effect with modest packing density], so maybe at this late date, kit builders will now be willing to part with this and/or other HF, woofer tweaks .
GM
HE12 Plan's 'Error 404' embedded link is [thankfully] on the net archive: http://web.archive.org/web/20031203150146/http://www.adireaudio.com/Files/HE12-1Plans.pdf
Also, in a PM re any HF driver tweaks such as damping the front chamber, Dan W. noted that it was stuffed with an unspecified amount of either 4/0 alum or stainless steel wool [memory fails and Yahoo mail has deleted all my mail prior to 2004
, though personally have used SS in other brands/models to good effect with modest packing density], so maybe at this late date, kit builders will now be willing to part with this and/or other HF, woofer tweaks .GM
The beta10cx is a different story, ill make a separate thread about that some day once I build a new 10" box, but attention and focus now is to see if I can improve my current 12" box without drastic measures like removing dust caps and relocate the horn or badly assembled home made crossovers
Anyhow the Seleniums and new crossovers arrived today, stocked and urge to open my speakers.
I'm surprised how quick parts express managed to get this overseas, from Friday to Monday is pretty impressive.
These T220TI drivers is huge compared to my memory of the ASD1001, will confirm once I open up my speaker again but will I need to strengthen my front baffle of all this extra weight? What is the story of JBL and Selenium btw? The webshop state Selenium but the sticker on the CD makes no mistake its JBL. Is Selenium brand phasing out?
Still waiting for the PSD2002, will be very interesting to compare it all.
Any nice simple measuring free programs I can use to share my findings??
Thanks for all tips.
Anyhow the Seleniums and new crossovers arrived today, stocked and urge to open my speakers.
I'm surprised how quick parts express managed to get this overseas, from Friday to Monday is pretty impressive.
These T220TI drivers is huge compared to my memory of the ASD1001, will confirm once I open up my speaker again but will I need to strengthen my front baffle of all this extra weight? What is the story of JBL and Selenium btw? The webshop state Selenium but the sticker on the CD makes no mistake its JBL. Is Selenium brand phasing out?
Still waiting for the PSD2002, will be very interesting to compare it all.
Any nice simple measuring free programs I can use to share my findings??
Thanks for all tips.
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I am about to jump on this train myself but can not decide if the 12” coax is best for my needs, will the 12” work in nearfield use? Is the power response for the 12” better then for the 10 or the 8 inch driver? Is the sound from these coax drivers good enough for an audiophile setup? Or are these drivers toys and money is better spent elsewhere?
Definitely not toys, Im using the 12CX/ASD1001 combo in my home "studio" semi-nearfield in a 10m2 room and very happy so far with the exceptions mentioned early in thread. Ive always loved coax speakers for close field due to coherence, and Ive always loved the body and effectiveness/effortlessness of a 12" compared to 10 or 8. The sound is big and honest. I used to have tiny Genelecs in my studio but they are now collecting dust. Playing loud is just a bonus with the PA drivers I don't really need that but nice to have the possibility. Above 15kHz not the best though, not as open as a dome tweeter. Depends on your requirements to flat response I guess. I have not tried the B10CX fully yet.
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