A TRUE ONE AND A HALF WAY SPEAKER

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Canada Rob

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A TRUE ONE AND A HALF WAY SPEAKER
« on: 7 Jul 2014, 08:24 pm »
Here is a true one and a half way speaker. 
The advantages are obvious such as:

1) Still a single point source
2) Double the the driver area
3) Higher efficiency
4) Lower impedance

Louis quotes:

"A while back I built a project.  The speaker was designed to use two full range drivers.  My intent was to use two of the same full range drivers.  I could use them in a bipolar multipoint format, but did this before.  I wanted to use both and not run both full range.
 
Using two of the same drivers has advantages as they share the workload and will be more sensitive running at 4 ohm.  Running both drivers full range would not be too accurate on the front baffle and would ruin my perfect point source.  I decided to run the top driver full range and the bottom driver to 300Hz.  All I needed to do is add a high quality air core coil for the bottom speaker.   
The transition of the drivers is spot on because they are the same and matched.  Both drivers share bass and mid bass duty and the speaker system is still a point source in the mids to treble.
 
I have heard others mention one and a half way before.
 
A full range driver and a tweeter is a two way.
A full range driver and a bass unit is a two way.

The pictured speaker is a true one and a half way."







DaveC113

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #1 on: 7 Jul 2014, 08:44 pm »
Congrats on a very clever design!  :thumb:

gab

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #2 on: 7 Jul 2014, 10:18 pm »
Here is a true one and a half way speaker. 
The advantages are obvious such as:

1) Still a single point source
2) Double the the driver area
3) Higher efficiency
4) Lower impedance

Louis quotes:

"A while back I built a project.  The speaker was designed to use two full range drivers.  My intent was to use two of the same full range drivers.  I could use them in a bipolar multipoint format, but did this before.  I wanted to use both and not run both full range.
 
Using two of the same drivers has advantages as they share the workload and will be more sensitive running at 4 ohm.  Running both drivers full range would not be too accurate on the front baffle and would ruin my perfect point source.  I decided to run the top driver full range and the bottom driver to 300Hz.  All I needed to do is add a high quality air core coil for the bottom speaker.   
The transition of the drivers is spot on because they are the same and matched.  Both drivers share bass and mid bass duty and the speaker system is still a point source in the mids to treble.
 
I have heard others mention one and a half way before.
 
A full range driver and a tweeter is a two way.
A full range driver and a bass unit is a two way.

The pictured speaker is a true one and a half way."






I don't know about the significance of the "one and a half" description, but I believe this is a pretty common design technique/approach to fix baffle step problems. Ref this thread:
 http://www.audiocircle.com/index.php?topic=101785.msg1030070#msg1030070
and specifically post 18 for a picture of what I think Louis did. Fixes the baffle step problem without the efficiency robbing resistor/inductor approach that is often/sometimes used. My $0.02

gab

mresseguie

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #3 on: 7 Jul 2014, 11:26 pm »
Admiring eyes want to know specs and prices. I assume such speakers sound best if supported by a fast subwoofer?  :thumb:

Canada Rob

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #4 on: 7 Jul 2014, 11:39 pm »
Admiring eyes want to know specs and prices. I assume such speakers sound best if supported by a fast subwoofer?  :thumb:
Subs need not apply, these have beautiful bass.  They will hopefully appear in the Omega Store within the next few weeks.

Louis O

Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #5 on: 8 Jul 2014, 02:43 am »
Hi All,

Many thanks Canada Rob for posting the speaker and thanks to everyone for the great comments. A lot more will be coming using the 1.5 way setup.

A bit of history on this model and it actually dates back to 2005. This is when I made this speaker. I had the idea as mentioned above in Canada Rob's post, but baffle step was not my motivation. I wanted to add drivers and keep my point source, but add more dynamics.

When I built this speaker it had Fostex drivers originally and then Hempcones. The cabinet is an R model and the finish is Ebony. During this time my ebony was matte and not semi gloss I use today. I was using Cardas Patented posts which I haven't used in a pretty long time. These speakers were also shown at a couple of Audio shows back then.

This set has been updated with fresh RS5's, info card on back, and the cabs are in almost perfect condition.

My speaker and design predates the link above by 7 years.

Thanks again,
Louis


gab

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #6 on: 8 Jul 2014, 05:24 am »
Hi All,

Many thanks Canada Rob for posting the speaker and thanks to everyone for the great comments. A lot more will be coming using the 1.5 way setup.

A bit of history on this model and it actually dates back to 2005. This is when I made this speaker. I had the idea as mentioned above in Canada Rob's post, but baffle step was not my motivation. I wanted to add drivers and keep my point source, but add more dynamics.

When I built this speaker it had Fostex drivers originally and then Hempcones. The cabinet is an R model and the finish is Ebony. During this time my ebony was matte and not semi gloss I use today. I was using Cardas Patented posts which I haven't used in a pretty long time. These speakers were also shown at a couple of Audio shows back then.

This set has been updated with fresh RS5's, info card on back, and the cabs are in almost perfect condition.

My speaker and design predates the link above by 7 years.

Thanks again,
Louis

Sorry Louis. I didn't realize you invented this approach and that it has nothing to do with baffle step correction.

I have a couple of questions.

Can a 2A3 amp still be used successfully with this lowered impedance?

What is the minimum impedance with the 2 drivers and at what frequency does this occur?

Is the efficiency of this design increased above 93 dB/w/m and if so how much?

Do you have some measurements you can share? That would be very helpful.

Looks like a great design! Will you be at RMAF this fall to demo these - would love to hear them, especially with a 2A3 amp driving them.

gab

Good Times

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #7 on: 8 Jul 2014, 01:14 pm »
Ah how good is this! That's a great idea, double up at the bottom end where you need some real air moving, and let the single driver still do its magic up top. Brilliant!

PS I love the Cardas binding posts, probably my favourite. Not cheap though!

gab

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #8 on: 8 Jul 2014, 03:10 pm »
Phil Bamberg explains what is going on with this design approach here:

http://bambergaudio.com/technical/2pt5.php

Even though he discusses a 2.5 speaker, the same discussion holds true for the 1.5.

gab

RDavidson

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #9 on: 9 Jul 2014, 02:52 am »
This is one of those "Why didn't someone think of this sooner?" types of things. It's so simple. Brilliant idea! Finally, essentially a "one way" (I know it's a 1.5 way) speaker that doesn't have a large, heavy, driver or a giant maze of horn loading, to achieve what I'm betting is fairly deep, fast, and tuneful bass that is in time with the main driver. Very very cool. :thumb:

Folsom

Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #10 on: 9 Jul 2014, 03:07 am »
Phil Bamberg explains what is going on with this design approach here:

http://bambergaudio.com/technical/2pt5.php

Even though he discusses a 2.5 speaker, the same discussion holds true for the 1.5.

gab

Glad someone mentioned him. It's not new, it just isn't used enough in some circles.

DaveC113

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #11 on: 9 Jul 2014, 05:55 am »
I had a set of 2.5 way bipole speakers back in '92... Mirage...  :thumb: 

JLM

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #12 on: 9 Jul 2014, 09:34 am »
So how does the sound of this compare to a bipole with the same two drivers?  In theory I'd much prefer the bipole as closer to a single point source.

Again this design feature is nothing new.  Paradigm, as just one popular example, has been doing it for decades.  Never been a big fan (why use a driver for what it's not intended for)?  Why not just add a sub (that can be adjusted)?  The the title of this thread says it all (half way), why not go all the way (to a 2-way)?  Or how about just going the route of the Bose 901 and use a whole bunch (9) of the same drivers?  Or a line array (and give up vertical imaging entirely)?  I see this as a slippery slope away from the single driver ideal.

DaveC113

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #13 on: 9 Jul 2014, 03:07 pm »
So how does the sound of this compare to a bipole with the same two drivers?  In theory I'd much prefer the bipole as closer to a single point source.

Again this design feature is nothing new.  Paradigm, as just one popular example, has been doing it for decades.  Never been a big fan (why use a driver for what it's not intended for)?  Why not just add a sub (that can be adjusted)?  The the title of this thread says it all (half way), why not go all the way (to a 2-way)?  Or how about just going the route of the Bose 901 and use a whole bunch (9) of the same drivers?  Or a line array (and give up vertical imaging entirely)?  I see this as a slippery slope away from the single driver ideal.

With the crossover at 300 Hz you're not giving up much if anything wrt the "single driver ideal". Bipoles need space, and not everyone has enough space for a bipole speaker.

There are issues with interference running multiple drivers full range in a line array, Danny at GR has built a bunch of line arrays and has posted some good info about the issues...

With a 2-way the drivers have to integrate well, with this design the integration will be perfect because they are the same driver, and since it was designed as a full range driver this works, probably better than a lot of 2.5 ways.

As far as the "single driver ideal", they aren't imo. They are the best compromise for a lot of applications and for a lot of people's preferences... but for a lot of people a compromise by adding other drivers for subs for midbass reinforcement might be the best compromise. Why not offer a products that fit more people's ideals? It will only lead to more sales and more happy customers. Those that want a pure single driver can still go that route through one of the many speakers Omega currently offers.

That's my take anyway... :green:

pstrisik

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #14 on: 9 Jul 2014, 03:31 pm »
With the crossover at 300 Hz you're not giving up much if anything wrt the "single driver ideal". Bipoles need space, and not everyone has enough space for a bipole speaker.

..........

As far as the "single driver ideal", they aren't imo. They are the best compromise for a lot of applications and for a lot of people's preferences... but for a lot of people a compromise by adding other drivers for subs for midbass reinforcement might be the best compromise. Why not offer a products that fit more people's ideals? It will only lead to more sales and more happy customers. Those that want a pure single driver can still go that route through one of the many speakers Omega currently offers.

That's my take anyway... :green:

 

I agree.  I'm basically running a 1.5 way, though not in the neat, integrated package Louis is presenting.  Running Super 7 XRS Alnico for the full range and two Rythmik F12 subs with low pass currently at 120hz for the ".5".  This is my preference actually, as I have fine grain control over the subs' low pass point, volume, and placement.  But this means two floorstanders and two large cubes for subs, so space can be an issue as well as complexity of setup.  Some will certainly prefer to have all of that in one pair of boxes factory tuned - no muss, no fuss.


Folsom

Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #15 on: 9 Jul 2014, 06:50 pm »


I agree.  I'm basically running a 1.5 way, though not in the neat, integrated package Louis is presenting.  Running Super 7 XRS Alnico for the full range and two Rythmik F12 subs with low pass currently at 120hz for the ".5".  This is my preference actually, as I have fine grain control over the subs' low pass point, volume, and placement.  But this means two floorstanders and two large cubes for subs, so space can be an issue as well as complexity of setup.  Some will certainly prefer to have all of that in one pair of boxes factory tuned - no muss, no fuss.

You're missing about 1.3 octaves in stereo, of reinforcement. That octave range is going to be much more capable on Louis's speaker. That being said, I have no doubt your setup sounds really good anyways, I'm just saying the new speaker has better capability in about 1.3 octaves.

Another trick by the under appreciated Phil, is to use drones to shrink the box size of the low fill. If you have an enclosure anyway.

pstrisik

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #16 on: 9 Jul 2014, 06:57 pm »
You're missing about 1.3 octaves in stereo, of reinforcement. That octave range is going to be much more capable on Louis's speaker. That being said, I have no doubt your setup sounds really good anyways, I'm just saying the new speaker has better capability in about 1.3 octaves.

Another trick by the under appreciated Phil, is to use drones to shrink the box size of the low fill. If you have an enclosure anyway.

Good point that my subs are in mono.  I could set them up in stereo, but they double their role in home theater, so my pre/pro is in control of them.  I can set low pass as high as 200, but I'm not sure the subs are designed for it.


cbarth

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Re: A TRUE ONE AND A HALF WAY SPEAKER
« Reply #17 on: 10 Jul 2014, 12:15 pm »
Just saw these beautiful speakers!  :o Really interesting to say the least...

Just for thought, how would this 1.5 concept work in the Super 3 XRS cabinets?

I just love the aesthetics/form factor of that speaker... You could sign me up for a pair if this was doable.... :D

Cbarth