[Ultralight]

I realize that this is a forum for full ranger speakers which has been my primary interest.

However, I hope this question is pertinent.   I realize that some of the advantages of full range include point source imaging, phase coherence, high efficiency etc.   However, the potential drawback could be the lack of ability to play very complex pieces such as full orchestra or have a full range frequency response.

So my question:

Why not coincident drivers?  (i.e. Tannoy) These seem to have the point imaging, phase coherence etc.   Perhaps not the efficiency but having a tweeter and woofer seem to get around the issue of reproducing a full frequency range, and yet have the effect of a single driver?   What are the disadvantages of coincident drivers compared to a single full range?

Thanks,
UL

[rjbond3rd]

I heard a coax SEAS recently which was very good.  Presumably, a coax is, or is close to being, time-aligned. But you still typically have an audible crossover, and it's usually right where the ear is most sensitive to phase.

Designing a top-notch crossover can be done, obviously, but it's usually a feat of engineering (and a bit of luck).  If you can get away with first order (6db/octave), you may be very pleased.

It's often just easier and cheaper to find a good full-ranger than to find a really coherent two-way.  You have to shop around and hear for yourself.  Every design has pros and cons.

[JLM]

Yes coaxial is better than not but, like a whizzer, the coaxial driver is either "riding" on the main driver (so it's soundwaves are added to those of the main driver that causes phasing problems) or is mounted in front of the main driver (again like a whizzer) and blocking/distorting the sound wave produced by the main driver.

Plus you have that nasty crossover, that adds phasing problems (hopefully below 100 Hz or above 10,000 Hz), eliminates the "active speaker" status you can have from a single channel of amplification per speaker, and robs power.

Note: not all single driver designs are high efficiency.  Tang Bang as some at 88 dB/w/m and E. J. Jordan (in reality) are mid 80's dB/w/m.

[SET Man]

Hey!

    I think the coincident driver speakers are the next best thing to wide band single driver speaker.

    Talking about the Tannoy. I've heard their Turnberry SE belong to one of member here couple of time. And I have to say they are one of my favorite 2 way speaker. So much so that if I wouldn't mind having a pair some similar model to that if I had money and space for second system. But even with that I still prefer my single driver speaker when is come to midrange, especially with female vocal range.

    It is true that coincident driver speakers are more coherence than those with separated tweeter mounted some distance away. But there still crossover involve and this is where the problem lies. Take the Tannoy Turnberry for example. The xover is right in the middle and the tweeter have 2nd order and woofer with 1st order. With that if the tweeter is connected with the same polarity as the woofer the soundwave coming out will be reversed than the woofer with a dip at the xover point. You can reversed the connections as the woofer to correct that that there will be a peak at the xover point I think. But with the same xover slope I think this will be less of a problem, but still you have two different drivers. Well, I'm no expert I'm sure some other will have better feedback on this subject.

    So, even the coincident drivers can give you a better time alignment than separated drivers it still have to use the xover and this is where things can get complicated. Well, the whole thing about single driver speaker is all about getting rid of the xover in the critical range.

Take care,
Buddy

[planet10]

The tannoy paper cones drivers are one that i would really like to play with...

On Wed this week i had a new to single driver fellow from Ottawa come up the mountain to taste test some FRs. He lives with a set of 10" Tannoy.

Mostly i has Mark Audio boxes in the living room, and as we progressed up the line the more impressed he was getting. Even picking up the subtle differences between A12eN in Classic GR Mar-Ken vrs the full-on Mar-Ken12.

The speaker that left the biggest impression on him thou was my not yet finished FAST demonstrator MTMs with CSS EL166eN (aka Mark Audio No6) + Fostex-based FF85KeN. At the XO point, the drivers are less than a quarter wave-length apart (ie essentially co-incident without the issues of a tweeter loaded by the main cone) with a wide overlap, in the flattest part of their impedance curves so a phase coherent 1st order series XO works well.

FAST (a full range with helper woofer) have the potential to give the best of both worlds. It has become almost standard procedure for open baffles. With conventional enclosures, one can start with an enjoyable FR system and add active powered woofers (not necessarily subs) to take the system up a notch at a later date.

dave

[JLM]

FAST (a full range with helper woofer) have the potential to give the best of both worlds. It has become almost standard procedure for open baffles. With conventional enclosures, one can start with an enjoyable FR system and add active powered woofers (not necessarily subs) to take the system up a notch at a later date.

dave

+1 (except for excessive complusive purists like me  )

[Raiderone]

The speaker that left the biggest impression on him thou was my not yet finished FAST demonstrator MTMs with CSS EL166eN (aka Mark Audio No6) + Fostex-based FF85KeN. At the XO point, the drivers are less than a quarter wave-length apart (ie essentially co-incident without the issues of a tweeter loaded by the main cone) with a wide overlap, in the flattest part of their impedance curves so a phase coherent 1st order series XO works well.

dave

What was the crossover point?  Just one inductor on the woofer and cap on the tweeter?  Or something more complicated, like a passive line level bi-amped setup?  Or combination of both?

[planet10]

XO somewhere 300-350. FF85KeN connected in series with paralleled EL166eN. 30uF shunting the woofers, 3mH shunting the mid-tweeter. Tube amp that puts out about the same power into 4 or 8 ohms. Still plan on seeing if i can tweak the XO further. And finish them including painting the FF85 bezels black.

http://www.diyaudio.com/forums/css/176790-el166-mtm-ml-tl.html



dave

[versus rider]

Yesterday I heard some Tannoy GRF's that a friend had built and liked them very much as I have enjoyed other Tannoy's in the past but they still struggle with complex music, maybe not as badly as single drivers but to my poor ears still noticeable. I could however live with some Tannoys if the need arose.

[Raiderone]

XO somewhere 300-350. FF85KeN connected in series with paralleled EL166eN. 30uF shunting the woofers, 3mH shunting the mid-tweeter. Tube amp that puts out about the same power into 4 or 8 ohms. Still plan on seeing if i can tweak the XO further. And finish them including painting the FF85 bezels black.

http://www.diyaudio.com/forums/css/176790-el166-mtm-ml-tl.html


dave

Thanks for the response.

According to the graph (at the CSS website) EL166eN rolls off pretty darned smoothly.  Interesting implementation.  Getting the mid/woof above does somehow give the sound weight and balance. 

Didn't think that a cap across them would be enough rolloff.  But, that is a pretty big coil across the mid/tweet.  Is there a huge difference when the mid/tweet ran full range (if you tried it)?  Or have you compared with a cap in series for the high pass?

[planet10]

I mucked and mucked with parallel XO, but when i wired the same components in series everything snapped into place. And one of the advantages of a series XO (if drivers are coincident) is close to perfect time response.

Not nearly the dynamic, loudness capabilities or cohesiveness with the FF85 running full out. I can get a limited 100 Hz capability out of the driver in a uFonken, probably not quite as low in the little TLs they are in, but the purpose is to flatten the impedance to better serve the XO.

dave