Advantages and disadvantages of having the woofer-mid in a 2-way "Run Wild," with no Woofer Leg on the Crossover?

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#21
Most modern drivers with their large magnets will peak instead of nicely & gradually fall off like the old Seas driver.
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#22
wchang said:
Enthusiastic language aside, this is how (nearly all) vintage 1950s pre-rock&roll high-end speakers worked, big "fullrange" driver (100-10000hz) run straight-through, augmented by a tiny driver with 1st-order high-pass filter capacitor. A suitable term for this class of speakers, fullrange straight-through augmented at the top and/or bottom, is F.A.S.T. In audiophile circles, it has long been an open secret that the very highly regarded speakers mentioned in this thread are not the usual "multi-way with crossovers", but instead each a throw-back to the vintage era of FAST. As mentioned already in this thread, stereo imaging (post-vintage-era of course) may not be so-well-served by FAST if crossed low, compared to having first-order both low- and high-pass whose phase offsets sum to cancel each other yielding flat amplitude and phase throughout. The "theory" is a bit subtle; I have confirmed it in practice. Higher order crossovers don't have this "magical" property.
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Thanks for the substantial contribution! As I mentioned in another thread, Irving M. Fried was my first mentor (a polite term for talking my ear off) in loudspeaker design. Fried's R3 remains one of the most memorably "musical" of my listening experiences from more than 40 years ago.

I certainly understand the 1st-order crossover love (part of the Duntech/Dunlavy "Secret Sauce). However, with a Fountek NeoCD3.0 ribbon tweeter, I think it prudent to follow Fountek's recommendation for 3rd order.

I have a perfectly good asymmetrical LR2/B3 crossover in my prototype right now. It's just that the TAS Wilson Benesch Eminence review started me down a path of "What IF"?

amb, john
 
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#28
I get the feeling that YouTube was recorded in a not very well treated room.

Simple, nice voice, but there seem to be some significant artifacts. How much is the speaker and how much is the “getting it on YouTube”. The speaker becomes convolved with everything else involved.

Is a full-rez direct recording of that available? Before it comes out the loudspeaker? Ie what goes into the pre-amp.

dave
 
#31
hifijim said:
The old school designers were very skilled at applying various varnishes and glues to paper cones to tailor the response to just what they wanted. Some polymer cone drivers were designed to have this kind of response.
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Winslow Burhoe's most recent design, the Direct Acoustics Silent Speaker II, indeed does have some kind of proprietary goop smeared on the outer periphery of the woofer cone, to the extent it makes the woofer look hand-made. http://directacoustics.com/?page_id=16
 
#32
OK! Tweaking and videography done.

Video 1: The speaker as it was, the woofer connected to the crossover, with a +2dB tweeter level boost to compensate for a predicted wide trough, as shown in the image.

Video 2: The speaker with the woofer disconnected to the crossover ("Running Wild"), but with a +2dB tweeter-level boost still in effect.

Video 3: I swapped out the Tweeter Level-Setting Resistors, putting the tweeter at +0db, making it -6dB from the woofer, to compensate for the efficiency disparity between the ribbon tweeter and the woofer-mid.

I love the midrange! I cheerfully admit that I have to do a LOT more critical listening, especially to the bass, as it is getting no help from the non-existent crossover.

Thanks everyone for the interesting contributions, and I will send a link to Winslow can read the nice things people are saying.




As I said in the last video's text, the Pink Noise test is very promising, and I am loving the detail and speed of the midrange... but, what I might have done is to Frankenstein a "Sounds Great, but Measures 'Meh!' loudspeaker."

ciao,

john
 

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#34
johnmarianmarks said:
Winslow Burhoe and I have lunch together (with his witty and charming wife) several times a year!

john
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Awesome John, please pass along my sincere regards also next time you see him, the Burhoe Blues I have are the speakers that really pushed me into audio (they were my uncles) his simplistic crossover tied with certain driver mechanics/parameters is my mantra for diy speaker building.

I’ve tried Huw’s replacement stuff and it doesn‘t hold a candle to the original, i just wish the tweeters were serviceable……they will soon be unobtainable.
 
#35
motokok said:
Will you next try to compare it to a "measures good" iteration?
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Hi, right now, my focus is to start somewhat all over again with a larger woofer in a larger enclosure. Anyway, I have a verbal agreement with a "name" loudspeaker designer (NB, that person is NOT Winslow Burhoe) to take over the work once I get it to a point where I am subjectively happy.

I played violin in youth orchestras and sang in school chorus, so the sounds I hear in my head (not to be confused with the voices inside my head calling "Gloria"), are different from what I might hear if if had spent that time in a garage trying to be the next Depeche Mode. So, there is a workflow plan that will keep my prejudices from being the last word.

Thanks,

john
 
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#36
The first loudspeakers i bought were Patterson Industry with 8” RSC FR. My next were EPI 100. 50s, 201s as well as all the others of the day at the dealer.

dave

PS: have a couple tweeters (an original and the later one with the fancy plastic bezel) in the give-away pile for anyone needs a replacement.
 
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#38
Almost every woofer or "mid-woofer" in existance has elevated distortion at higher frequencies. Don't let a smoothly falling frequency response lull you into thinking that you can run it as high as you want or avoid using a lowpass filter completely.

Consider the following frequency response. Looks pretty benign, right? No significant issues using this out to 6-7kHz?
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Now consider the harmonic distortion of the same driver. There is elevated 3rd and 5th order distortion from 900Hz up to around 3kHz so you could not want to cross this woofer higher than 1kHz in order to maintain the lowest possible distortion
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Another example with a less satisfactory looking frequency response. Should be ok as long as we can avoid that big peak starting at 5kHz, right?
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Wrong. Distortion rises significantly starting as low as 1kHz.
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#39
Anomalies such as metal cone resonances high up show as distortions on related lower frequencies. That is certainly clear on the measurement of the Fountek. But here one should question the validity and interpretation of the measurement method itself too.

Not that I want to propagate 'free running mid woofers'. It's dumb. There is an electric LP filter in every dynamic speaker: the voice coil. It's acting quite badly, as it's value changes with the position of the cone. Apart from all other (breakup) issues, you seize to bring down a big nonlinearity by using that voice coil LP alone.
 
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