John_E_Janowitz said:
I'd vote for a moderately stiffer spider, so the Qts for the 18" driver falls somewhere between 0.5 and 0.65. I expect to be using monopole subs below 50 Hz anyway, so response below 50 Hz is not really that useful. Aside from using subs, I am quite happy with the overall balance of speakers that have a LF rolloff around 50 Hz - I listened to the Ariels for many years without a subwoofer, and their in-room Fs in the 50~55 Hz range.
(The rest of the specs look really great! What are the proposed dimensions for the exterior diameter, baffle cutout, and bolt-circle diameter?)
The general idea for this system is for the sub and the supertweeter to extend the response, but not be essential for musical enjoyment. The real system is the 18" woofer, the 12" midbass, and the large-format compression driver on a low-diffraction horn/waveguide.
Well, that's certainly true. Very few systems can reproduce that astounding sense of bass rolling around that you hear in a big, beautiful symphony hall - thrills aplenty in "Pictures at an Exhibition", "Carmina Burana", or the "Rite of Spring".
Not the same as dinosaur thumps or a phaser blasts from a 7.1 Dolby Digital soundtrack in a multiplex theater. That's noise, not bass.
Not the same as dinosaur thumps or a phaser blasts from a 7.1 Dolby Digital soundtrack in a multiplex theater. That's noise, not bass.
Lynn Olson said:
In the ''System'' concept I would certainly give paramount importance to the room factor and the way that it is energized. Evenly is the key.
The rolling, enveloping, breathing bass of the huge concert hall is due to the fact that in such dimensions, the modal region stops low, at 10-20Hz. Higher than that, the modes become dense, much like they become in a domestic room after 150-200Hz.
Lynn Olson said:
Hi Lynn,
Just curious, who's going to wind your step-down transformers? Will the attenuation be fixed or is there room for switching (less padding)? A bit OT, what cap types/manuf. do prefer these days for the passive xo, at least after you've finished fine tuning? Thank you.
regards,
fred
Re: GPA and 18Sound Drivers - Front View
Lynn,
Do you plan to first listen to those drivers full-range on a simple baffle (as you stated previously) ?
I think there are quite a few here (myself included) that would be greatful for detailed measurements and listening impressions of those 3 drivers -- those two + TD12M (or, better, the TD12M's OB variant ).
Regards,
Florian
Lynn Olson said:
Lynn,
Do you plan to first listen to those drivers full-range on a simple baffle (as you stated previously) ?
I think there are quite a few here (myself included) that would be greatful for detailed measurements and listening impressions of those 3 drivers -- those two + TD12M (or, better, the TD12M's OB variant ).
Regards,
Florian
How do you pronounce it? mmmmmm
came from the name All Tech then they joined with Lansing to form Altec Lansing. Have a look here or at the Lansing Heritage site.
http://en.wikipedia.org/wiki/Altec_Lansing
came from the name All Tech then they joined with Lansing to form Altec Lansing. Have a look here or at the Lansing Heritage site.
http://en.wikipedia.org/wiki/Altec_Lansing
288B
Thanks for the info Lynn
Nice curves on the 288B . Looks like you also get the 'BBC dip' for free !
Crafty ideas on the step-down attenuation .
I would guess a guy called Bud might be making those step-downs . Will you be asking for some multi-tapping on the secondary to give you some wiggle-room on the attenuation ?
I guess the small-ish size of the cores and the high-current regime at that end of the system will get the low-level stuff across very well ? ( as you know, the 'stuff between the notes' is always my concern ) .
MJ
Thanks for the info Lynn
Nice curves on the 288B . Looks like you also get the 'BBC dip' for free !
Crafty ideas on the step-down attenuation .
I would guess a guy called Bud might be making those step-downs . Will you be asking for some multi-tapping on the secondary to give you some wiggle-room on the attenuation ?
I guess the small-ish size of the cores and the high-current regime at that end of the system will get the low-level stuff across very well ? ( as you know, the 'stuff between the notes' is always my concern ) .
MJ
Two names on the custom transformers - Bud Purvine of O-Netics and Dave Slagle, two of the nicest guys you'd ever want to meet. Both do wonderful work, no complaints at all. In the UK, there's Sowter, in Sweden, there's Lundahl, in Hollard, there's Tribute, and many others I can't think of right now.
In principle it would be desirable to have the basic step-down ratio with 4 or 5 additional taps with 1 dB spacing, but additional taps are a fairly major hassle for the winder. In practice, the initial measurements and auditioning will be done with an L-pad, which will get the overall spectra in the right shape. The transformer has a stronger effect on subjective qualities like resolution, tonality, all that good musical-enjoyment stuff - but cruder matters like balance and freedom from resonance can be done with resistive attenuation.
The initial measurements and audition will be done on a large, IEC-style baffle - 85 by 135 cm if I recall right, with the driver off-center. Various permutations of the initial, rough crossover can be done with clip-leads - rolloffs, notch filters, things like that. I do most auditioning with pink-noise, not music, and fiddle around with notch filters to see how filterable the resonances are.
The easiest thing to do is sit at the right distance, listen, and switch the filter in and out as it is tuned up and down. When you hit the right spot, the coloration suddenly drops out. Precision adjustment of notch filters needs to be done with real-time CSD measurements, chasing down the resonances in the time domain. With any luck, the subjective and objective notch-filter tuning should line up pretty closely. If they don't, well, more work is needed to find out why.
The high-pass filters are tuned similarly for smoothest possible highpass characteristics, continually cross-checking with measurements, and the lowpass filters are complements of the highpass filters. I always do the highpass filters first, since they critically affect the excursion of the HF radiators, and getting a smooth rolloff through the crossover region is not trivial. The choice of highpass filters (and any required shaping) for important drivers like the tweeter (in this case the compression driver + horn/waveguide) has a strong effect on the sound of the entire speaker system.
Computer modelling software is all well and good, but subjectively and objectively flat are not always the same - and when I say subjectively flat, I mean with pink-noise, not music. Music comes later, after the worst of the colorations are chased out.
When I get annoyed at hifi shows is when I hear speakers (most of them, particularly the $50,000-on-up models) that have obviously never been pink-noise auditioned by the designers. This is unforgivable - pink-noise audition goes back fifty years, the people who design these overpriced monstrosities should have heard of it by now.
Pink-noise coloration is so gross that silly things like cabling and amplification has no effect, which is partly why I use it. In addition, if a speaker has obvious pink-noise coloration, ALL the music played through it will be stamped with that coloration. It's only when a speaker can do a reasonable simulation of the sound of falling water we can talk about subtler aspects of reproduction, like getting the voices right (which is the next priority).
I have a fairly basic view of loudspeakers - they have to reproduce pink-noise and voices with some degree of realism, or they can't be considered high fidelity. Instrumentation and computer simulation have to serve the subjective experience, not the other way around.
In principle it would be desirable to have the basic step-down ratio with 4 or 5 additional taps with 1 dB spacing, but additional taps are a fairly major hassle for the winder. In practice, the initial measurements and auditioning will be done with an L-pad, which will get the overall spectra in the right shape. The transformer has a stronger effect on subjective qualities like resolution, tonality, all that good musical-enjoyment stuff - but cruder matters like balance and freedom from resonance can be done with resistive attenuation.
The initial measurements and audition will be done on a large, IEC-style baffle - 85 by 135 cm if I recall right, with the driver off-center. Various permutations of the initial, rough crossover can be done with clip-leads - rolloffs, notch filters, things like that. I do most auditioning with pink-noise, not music, and fiddle around with notch filters to see how filterable the resonances are.
The easiest thing to do is sit at the right distance, listen, and switch the filter in and out as it is tuned up and down. When you hit the right spot, the coloration suddenly drops out. Precision adjustment of notch filters needs to be done with real-time CSD measurements, chasing down the resonances in the time domain. With any luck, the subjective and objective notch-filter tuning should line up pretty closely. If they don't, well, more work is needed to find out why.
The high-pass filters are tuned similarly for smoothest possible highpass characteristics, continually cross-checking with measurements, and the lowpass filters are complements of the highpass filters. I always do the highpass filters first, since they critically affect the excursion of the HF radiators, and getting a smooth rolloff through the crossover region is not trivial. The choice of highpass filters (and any required shaping) for important drivers like the tweeter (in this case the compression driver + horn/waveguide) has a strong effect on the sound of the entire speaker system.
Computer modelling software is all well and good, but subjectively and objectively flat are not always the same - and when I say subjectively flat, I mean with pink-noise, not music. Music comes later, after the worst of the colorations are chased out.
When I get annoyed at hifi shows is when I hear speakers (most of them, particularly the $50,000-on-up models) that have obviously never been pink-noise auditioned by the designers. This is unforgivable - pink-noise audition goes back fifty years, the people who design these overpriced monstrosities should have heard of it by now.
Pink-noise coloration is so gross that silly things like cabling and amplification has no effect, which is partly why I use it. In addition, if a speaker has obvious pink-noise coloration, ALL the music played through it will be stamped with that coloration. It's only when a speaker can do a reasonable simulation of the sound of falling water we can talk about subtler aspects of reproduction, like getting the voices right (which is the next priority).
I have a fairly basic view of loudspeakers - they have to reproduce pink-noise and voices with some degree of realism, or they can't be considered high fidelity. Instrumentation and computer simulation have to serve the subjective experience, not the other way around.
Hello Lynn
You may find this thread useful if you ever decide to try to wind your own.
Rob
http://audioheritage.csdco.com/vbulletin/showthread.php?t=846&page=1&pp=15
You may find this thread useful if you ever decide to try to wind your own.
Rob
http://audioheritage.csdco.com/vbulletin/showthread.php?t=846&page=1&pp=15
In the last several weeks I've been bashed by the Lansing Heritage Forum and now, the GoodSoundClub of Boston - not to mention the continued high regard of the Audio Asylum High Efficiency forum.
There's finally something all three can agree on - really, who would have thought it possible? To paraphrase a famous American, I'm a uniter, not a divider.
There's finally something all three can agree on - really, who would have thought it possible? To paraphrase a famous American, I'm a uniter, not a divider.