You can use mutiple drivers or play with directivity such as putting the speakers in a corner.I was also told once that unicorns exist and pigs fly.
Sorry, I couldn't resist.
A 110dB/W woofer is a physical impossibility.
There are only three practical ways to increase efficiency:
- increase the radiating surface (Sd) - but there are practical limits
- decrease the moving mass (Mms) - but here too there are practical limits before the cone begins to flex uncontrollably
- increase the magnetic force factor (BL^2/Re) - but if increased too much, then the speaker loses all capability of reproducing low frequencies, i.e. it ceases to be a Woofer
If you actually do the calculations, the practical limit for, say, a 15" woofer over the intended frequency range (i.e. NOT in a narrow spike around 1kHz) is ~100dB/W(m).
Marco
Lynn are you talking about biamping the GPA 416? You don't think the speaker would lose some of its coherence since the GPA covers some of the lower midrange?
Thanks for latest updates Gary. Never thought I would say I was looking forward to when I can retire my Quad ESL!
It was.common practise in the JBL pro monitors of the 70s.
The iron core auto transformer is,tapped at a ratio for the required attenuation..
The overall inductance L is split at the tap and forms a series L and paperwork L to ground.
A resister across the input side damps the impedance.
But this is nothing we do these days? Then I am left using huge inductors to get a 3rd order filter at 250Hz for a 16-ohm driver. Thanks for the help anyway.
In context of the history of crossover design Not suitable for that frequency, best to biamp as is normal practise for SOA systems.
The problem at 250 hertz is the HP is effected by the resonance of the mid driver and the woofer response ends up forming a band pass with the bump around 100-150 hertz, then here is the DCR and losses that are inevitable which is sub optimal> biamp.
I should point out that even bi amp of the horn in practise leads to less then acceptable S/N given the sensitivity of the driver/ horn combo. I would therefore recommend bi amp the mid bass section and use passive (auto transformer or L Pad for mid/ horn crossover point.
I propose to you my First Watt B4 in this way and adopt optimisation and voicing with Leap 5 Crossover Shop and LMS
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Why not use cored inductors? They're available in high mH values and don't break the bank.
In my own passive crossover I use Mundorf Feron transformer core coils for the larger values:
An externally hosted image should be here but it was not working when we last tested it.
These are definitely "very hi-fi", I can assure you.
A 10 mH one wound with 2.0 mm wire has 0.2 Ohm DCR and retails for ~ 100 €.
Even lower-DCR versions are available, e.g. 'Zero Ohm' transformer coils wound with up to 3.0 mm wire, which give only 0.07 Ohm for a 10 mH coil:
Mundorf - Inner Excellence
Marco
I would say that cored inductors not being very hifi is a myth.
Fear is one of the greatest human enemies and it seems some
profit from it.
I would recommend this kind of product without hesitation.
Not overpriced and of decent quality. In my mind it would not
make much sense to spend substantially more money.
SuperQ Steel Core Coils | ERSE
I would like to take a few lines to thank Lynn for this thread, and Gary and so many others for your generous contributions. Following this thread over the years has been a source of education and inspiration.
About a year ago, my brother and I decided to build two pairs of speakers inspired by the "beyond the ariel" model.
After some simulation and measurements, we have finished a two way configured as follows:
1. Radian 745NEO/Be (16 ohm) driver, Azurahorn AH425, 3rd order high pass at ~772 Hz, connected to Tap #10 (-15 dB) of a Werner (mast_mutter) autotransformer, 15-ohm swamping resistor and no Zobel.
2. TAD TL-1601B (alnico), in 4.65 cu ft sealed enclosure, 6th order low pass at ~664 Hz, with Zobel circuit.
3. Offset: Back edge of horn mouth flush with front edge of woofer rim. Polarities: (+) on TAD and (-) on Radian. Horn raised a few inches (or angled upwards) to reduce diffraction/reflection caused by the front-top edge of the bass cabinet.
This two way is quite enjoyable "as is". Really. But some might feel a need to add a subwoofer or a tweeter.
The crossover point (~710 Hz), JMLC profile horn, 1.4 inch throat, large alnico mid-woofer, passive crossover, high sensitivity, etc., are all characteristics that contributed importantly to this design. We are grateful to Lynn and team for leading the way.
My brother and I are playing with a three way version using the Yamaha JA6681B on a AH425 tailored for its throat size. This second design shows promise, but is not yet as nicely integrated as the above two way.
Cheers - Pierre
About a year ago, my brother and I decided to build two pairs of speakers inspired by the "beyond the ariel" model.
After some simulation and measurements, we have finished a two way configured as follows:
1. Radian 745NEO/Be (16 ohm) driver, Azurahorn AH425, 3rd order high pass at ~772 Hz, connected to Tap #10 (-15 dB) of a Werner (mast_mutter) autotransformer, 15-ohm swamping resistor and no Zobel.
2. TAD TL-1601B (alnico), in 4.65 cu ft sealed enclosure, 6th order low pass at ~664 Hz, with Zobel circuit.
3. Offset: Back edge of horn mouth flush with front edge of woofer rim. Polarities: (+) on TAD and (-) on Radian. Horn raised a few inches (or angled upwards) to reduce diffraction/reflection caused by the front-top edge of the bass cabinet.
This two way is quite enjoyable "as is". Really. But some might feel a need to add a subwoofer or a tweeter.
The crossover point (~710 Hz), JMLC profile horn, 1.4 inch throat, large alnico mid-woofer, passive crossover, high sensitivity, etc., are all characteristics that contributed importantly to this design. We are grateful to Lynn and team for leading the way.
My brother and I are playing with a three way version using the Yamaha JA6681B on a AH425 tailored for its throat size. This second design shows promise, but is not yet as nicely integrated as the above two way.
Cheers - Pierre
But how about designing this 3rd order highpass? This is to me a more complicated question. I am sure any inductor will do the job. I see that different calcultors give different values. If I want 3rd order highpass and the a 1st order lowpass because of beaming, what kind of network do you recommend here?
Can the calculators be trusted?
Can the calculators be trusted?
Rewind,
I'm not certain who is it you are asking but I might as well
say a few words. Whenever you want to do a proper XO filter
for any driver, you ought to make an impulse response
and impedance measurement and import it in a simulation
program where you have the means to virtually test some kind of
filter. Online calculators assume an impedance and FR to be a flat
line which is not realistic, so the results are not too.
I'm not certain who is it you are asking but I might as well
say a few words. Whenever you want to do a proper XO filter
for any driver, you ought to make an impulse response
and impedance measurement and import it in a simulation
program where you have the means to virtually test some kind of
filter. Online calculators assume an impedance and FR to be a flat
line which is not realistic, so the results are not too.
Thank you, Pierre, for posting your results. It's good to know there are four pairs that are up and running ... in Canada, Pacific Northwest USA, and Australia. I'm sure you've found that the loudspeaker is extremely revealing of amplifier quality ... something I found with the initial rough prototypes and that Gary Dahl also discovered.
The other striking aspect, aside from tonality, are the very deep and spacious images, something I'd not heard from many horn systems before. My thanks go to JMLC and Bjorn Kolbrek for a horn with really good time response, and to Brush Wellman/Materion for the superb beryllium diaphragm.
Click here for marco_gea's useful and interesting JMLC-family crossover thread.
My personal preference are crossovers with acoustically in-phase drivers (within 5 degrees of each other), even if it's at the expense of minor ripples in the FR. The driver offset is a free variable, since the AH425 sits on top of the bass cabinet, with 2~3 inches (50~75mm) of vertical clearance.
The other striking aspect, aside from tonality, are the very deep and spacious images, something I'd not heard from many horn systems before. My thanks go to JMLC and Bjorn Kolbrek for a horn with really good time response, and to Brush Wellman/Materion for the superb beryllium diaphragm.
Click here for marco_gea's useful and interesting JMLC-family crossover thread.
My personal preference are crossovers with acoustically in-phase drivers (within 5 degrees of each other), even if it's at the expense of minor ripples in the FR. The driver offset is a free variable, since the AH425 sits on top of the bass cabinet, with 2~3 inches (50~75mm) of vertical clearance.
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Dear Lynn,
I'm sure that is true. On this very topic, any chance of getting a response to my related question? Beyond the Ariel - post #11386
Thanks!
Marco