single driver OB....
the "JE Labs" style (which is a Japanese design from the magazine Stereo Sound "Tube Kingdom") works very well. I cannot really explain it completely, but a couple of things make sense to me.
The dimensions of the baffle , essentially the same as Quad ESL 57s, and Wharfedale SFB3s loudspeakers, somehow "works". Is it a doubling of the baffle size, with the driver mounted only 13" or so up from floor? Is there "magic" in the dimensions? I don't know. And to be honest, I don't care ---it just works.
I had modified the OB by placing a full width "shelf" between the uprights, and a similar sized board between the uprights at the bottom of them. The result? As much bass I need or want. Everyone who I have suggested this to has indicated that the need for bass has been all but eliminated. All who have heard them are completely amazed.
The thing that stands out regarding the bass, is the lack of what I call "physical impact". It's pretty much all there, but doesn't hit you with a pressure wave. It is deep, but not physical.
I've tried these baffles with Oxford J10/ Vifa tweeter DIY co-axials, and Hemp Acoustic Fr8.0c drivers. Neither failed to make music in a convincing manner. However, these were driven by two different 125 watt/channel (RMS) amplifiers--a McCormack DNA 0.5 deLuxe, and a Yamaha B2 VFET . Both have a fair bit of control over the drivers.
Next up---an old pair of Altec Lansing 409-8C drivers, driven by tubes and maybe a try with my 41Hz, amp6 Basic.
This is in no way meant to argumentative with any. It is just meant to suggest that sometimes going against conventional wisdom can lead to amazing results.
Having said all of this, I have read the complete paper MJK presented regarding a passive OB project, and cannot argue, nor deny that this loudspeaker , and any improvements made to it would certainly be a great speaker at a very reasonable price. I have to believe MJK's speaker, or similar could be easily put together for the suggested budget.
stew
the "JE Labs" style (which is a Japanese design from the magazine Stereo Sound "Tube Kingdom") works very well. I cannot really explain it completely, but a couple of things make sense to me.
The dimensions of the baffle , essentially the same as Quad ESL 57s, and Wharfedale SFB3s loudspeakers, somehow "works". Is it a doubling of the baffle size, with the driver mounted only 13" or so up from floor? Is there "magic" in the dimensions? I don't know. And to be honest, I don't care ---it just works.
I had modified the OB by placing a full width "shelf" between the uprights, and a similar sized board between the uprights at the bottom of them. The result? As much bass I need or want. Everyone who I have suggested this to has indicated that the need for bass has been all but eliminated. All who have heard them are completely amazed.
The thing that stands out regarding the bass, is the lack of what I call "physical impact". It's pretty much all there, but doesn't hit you with a pressure wave. It is deep, but not physical.
I've tried these baffles with Oxford J10/ Vifa tweeter DIY co-axials, and Hemp Acoustic Fr8.0c drivers. Neither failed to make music in a convincing manner. However, these were driven by two different 125 watt/channel (RMS) amplifiers--a McCormack DNA 0.5 deLuxe, and a Yamaha B2 VFET . Both have a fair bit of control over the drivers.
Next up---an old pair of Altec Lansing 409-8C drivers, driven by tubes and maybe a try with my 41Hz, amp6 Basic.
This is in no way meant to argumentative with any. It is just meant to suggest that sometimes going against conventional wisdom can lead to amazing results.
Having said all of this, I have read the complete paper MJK presented regarding a passive OB project, and cannot argue, nor deny that this loudspeaker , and any improvements made to it would certainly be a great speaker at a very reasonable price. I have to believe MJK's speaker, or similar could be easily put together for the suggested budget.
stew
If you think about a full range driver in a box you really have a two way system, the box is the bass driver and an acoustic crossover is used to control the displacement of the driver at low frequencies.
I have thought about this a great deal. If you consider one of my horn designs with a wizzer its more like a 5 way. TL initial action, horn second action, baffle third action,driver fourth action, wizzer fifth action. the effort is in matching the XO and the energies at different points that you can control.
ron
I have thought about this a great deal. If you consider one of my horn designs with a wizzer its more like a 5 way. TL initial action, horn second action, baffle third action,driver fourth action, wizzer fifth action. the effort is in matching the XO and the energies at different points that you can control.
ron
So following the train of thought a little bit further. When you put a single full range driver in an OB you have a system with a built in acoustic high pass filter at a frequency determined by the baffle's size and shape. Without another mechanism to fill in the bass you end up with a rolled off low frequency response. Even with a very large baffle you are going to struggle to produce sufficient bass below 100 Hz. While it may sound good at first, and give a sense of great detail and open airy sound, it will be bass light and could be much better if you added a suitable dedicated bass driver with some form of electical, acoustic, or mechanical crossover that compliments and blends with the OB roll off. All you have to do is run some simulations or make some measurements with a single full range driver positioned anywhere on an OB to clearly see the picture and the resulting attenuated low frequency response.
So following the train of thought a little bit further. When you put a single full range driver in an OB you have a system with a built in acoustic high pass filter at a frequency determined by the baffle's size and shape. Without another mechanism to fill in the bass you end up with a rolled off low frequency response. Even with a very large baffle you are going to struggle to produce sufficient bass below 100 Hz. While it may sound good at first, and give a sense of great detail and open airy sound, it will be bass light and could be much better if you added a suitable dedicated bass driver with some form of electical, acoustic, or mechanical crossover that compliments and blends with the OB roll off. All you have to do is run some simulations or make some measurements with a single full range driver positioned anywhere on an OB to clearly see the picture and the resulting attenuated low frequency response.
Exactly. However i doubt that a single driver will accomplish this regardless of baffle size. Long wavelengths require movement of a piston that can displace enough volume to accomidate a balance of higher wavelengths. In the end it still takes two (or more)transducers to effectivly perform. I am not talking a coiax as thats two transducers with a given XO. At least this is current technology, if something new developes then i am incorrect.
ron
Exactly. However i doubt that a single driver will accomplish this regardless of baffle size. Long wavelengths require movement of a piston that can displace enough volume to accomidate a balance of higher wavelengths. In the end it still takes two (or more)transducers to effectivly perform. I am not talking a coiax as thats two transducers with a given XO. At least this is current technology, if something new developes then i am incorrect.
ron
nicoch46 said:
F3 is Zv9 (and vice versa), with some minor differences
F3 without feedback sounds like an F2, but has a bit different sonic signature, ( a bit of warmth, you may compare that to a single ended triode sound). This is just my subjective opinion, and depends on the type of speakers/box (or no box) that you are using.
It is a really good amp for a fullranger in the biamped OB 😉
ronc said:
Yes you are right, maybe this is interesting for you.
www.dipol-audio.de
This solution works down to 60 ... 70 Hz depending
on room and positioning.
Basic concept is to compensate baffle rolloff by increasing
radiation resistance of drivers towards lower frequencies.
The drivers distances become smaller in relation to
wavelength with lower frequencies. This compensates
baffle rolloff, which would start at some hundred Hz with
a narrow baffle like that (19cm).
The spacing of the array needs less drivers than a normal
line array.
You can have a look at the simulations.
There is power tapering by grouping the drivers and by
a crossover network, which distributes voltage to the
upper 3 group of drivers to get prominent at higher
frequencies above 2 Khz.
There is still some compensation to do in crossover, but
there is no excessive baffle step.
FR 125s is used as a driver. Maybe you want to adapt the
concept to a driver of your choice to meet your
price limit ... maybe with a larger or wider baffle, don't know.
For the baffle simulations i used "The Edge" .
Cheers Oliver
Hi Nicoch 46 -
My Wife really likes the wave guides you did with the Visatons.
Any chance you could share the pattern?
Really sharp looking.
Bluto
My Wife really likes the wave guides you did with the Visatons.
Any chance you could share the pattern?
Really sharp looking.
Bluto
sorry
A nice driver for open-baffle under 500 euros is the
Fertin 20s . I has a fs: 27hz and a qts of 0.42 with a
tube amp you can get the qts over 0.5 + ; ideal for
open-baffle. With the Fertin open-baffle plan , or a
U shape baffle: bass is sharp and good. I have a
pair in open-baffle.
Or if you wish to upgrade and get right away the best;
it will cost you more (900euros each) and you get the
Fertin 20ex in open-baffle. Ask Peter Daniel , he has
a pair in infinite baffle....
For info on the 20s; look at the thread;
Fertin full range speaker by Cherel.......
Fertin 20s . I has a fs: 27hz and a qts of 0.42 with a
tube amp you can get the qts over 0.5 + ; ideal for
open-baffle. With the Fertin open-baffle plan , or a
U shape baffle: bass is sharp and good. I have a
pair in open-baffle.
Or if you wish to upgrade and get right away the best;
it will cost you more (900euros each) and you get the
Fertin 20ex in open-baffle. Ask Peter Daniel , he has
a pair in infinite baffle....
For info on the 20s; look at the thread;
Fertin full range speaker by Cherel.......
got some time to hunt?
If you can find a set of JBL 123A or 2213 12" woofers, they work exceptionally well in a short, squat baffle. Mine is trapezoidal, with the longest edge on the floor, and the woofer mounted just above floor level (1"). The XO is 1st order series @ 500Hz to a fostex ff85k, though you can use a more sensitive larger fullrange if you're so inclined. The ff85k isn't as sensitive as the woofer, which also gets a boost because it's floor-mounted. The baffle is 22" tall, tilted back to align the woofer/midtweet acoustic centers, and about 1.25m wide at the bottom edge, tapered to about .75m.
Floor bounce? WHAT floor bounce! Kidding aside, you may encounter some artifacts due to the floor-height loading. I haven't been able to detect any, as I think the cancellation is sufficiently spread between the 2 driver's bandwidths, so any steep notches are helped out by the other driver (nice benefit of 1st order XOs: you can avoid some of the worst of narrow band cancellations b/c there's so much overlap)
If you can find a set of JBL 123A or 2213 12" woofers, they work exceptionally well in a short, squat baffle. Mine is trapezoidal, with the longest edge on the floor, and the woofer mounted just above floor level (1"). The XO is 1st order series @ 500Hz to a fostex ff85k, though you can use a more sensitive larger fullrange if you're so inclined. The ff85k isn't as sensitive as the woofer, which also gets a boost because it's floor-mounted. The baffle is 22" tall, tilted back to align the woofer/midtweet acoustic centers, and about 1.25m wide at the bottom edge, tapered to about .75m.
Floor bounce? WHAT floor bounce! Kidding aside, you may encounter some artifacts due to the floor-height loading. I haven't been able to detect any, as I think the cancellation is sufficiently spread between the 2 driver's bandwidths, so any steep notches are helped out by the other driver (nice benefit of 1st order XOs: you can avoid some of the worst of narrow band cancellations b/c there's so much overlap)
If you mean material, I used ply. 3/4" laminated to 1/4". The FF85k was mounted to the 1/4" with the 3/4" largely removed from the back of the driver so it could breathe. The 1/4" was also overcut to reduce the profile of the frame on the 12", the cutout for which also has rounding over to encourage free airflow.
I used holey bracing on the back panel, as well as using a central brace as a footer and magnet brace.
I used holey bracing on the back panel, as well as using a central brace as a footer and magnet brace.
''The 215sb no needs bsc e qts=0.8 no match on paper for 20s''
Does a driver with a fs:50hz-qts:0.8-93db have better bass
in open-baffle then a driver with a fs:27hz-qts:0.42-96db?
Is the fs of a driver important in o-b?
In o-b the lost in lf is -6db per octave below the ob bass
cut off and then -18db below the raisonance of the driver.
So below 50hz the supravox drops -18db wheras the
20 drops -18db at the fs=27hz. So having a high fs isn't
advantageous in ob.
The fs is also important in establishing the low frequency
roll off. If you look at the the graph in Dominique Pétoin site
you see that not only the qts detemine the bass roll off but
also the fs of a driver. So you don't get more much bass extension with a high fs and high qts driver than a
a fs= 27hz and a qts=.042.
http://www.petoindominique.fr/php/plancourbe.php
If you use a tube amp with a high output impedance with
a driver with a qts=042 then you increase the qts to
around 0.5 which is critical damping. Using the same amp
with a driver with a qts=0.8 bring the qts close to 1;
the quality of the bass could be compromise ; a loose bass
compare to a punchy bass (qts:0.5)
http://www.enjoythemusic.com/Magazine/equipment/0606/visation_nobox_bb_loudspeaker.htm
Increasing the qts to 0.8 comes with a lost in efficiency:
93db compare to 96db with qts of 0.42. This takes X2 to
power with the higher qts driver. So you would need at least
20w to get to 105db with the supravox as with the
20s 8-10w would be enough.
So a high fs and a high qts sometime not the best answer.
-You get a sharp roll off under the driver fs;
-the lf roll off isn't much better
- you loose efficiency
- you get lower quality bass (a tight bass is very important)
Does a driver with a fs:50hz-qts:0.8-93db have better bass
in open-baffle then a driver with a fs:27hz-qts:0.42-96db?
Is the fs of a driver important in o-b?
In o-b the lost in lf is -6db per octave below the ob bass
cut off and then -18db below the raisonance of the driver.
So below 50hz the supravox drops -18db wheras the
20 drops -18db at the fs=27hz. So having a high fs isn't
advantageous in ob.
The fs is also important in establishing the low frequency
roll off. If you look at the the graph in Dominique Pétoin site
you see that not only the qts detemine the bass roll off but
also the fs of a driver. So you don't get more much bass extension with a high fs and high qts driver than a
a fs= 27hz and a qts=.042.
http://www.petoindominique.fr/php/plancourbe.php
If you use a tube amp with a high output impedance with
a driver with a qts=042 then you increase the qts to
around 0.5 which is critical damping. Using the same amp
with a driver with a qts=0.8 bring the qts close to 1;
the quality of the bass could be compromise ; a loose bass
compare to a punchy bass (qts:0.5)
http://www.enjoythemusic.com/Magazine/equipment/0606/visation_nobox_bb_loudspeaker.htm
Increasing the qts to 0.8 comes with a lost in efficiency:
93db compare to 96db with qts of 0.42. This takes X2 to
power with the higher qts driver. So you would need at least
20w to get to 105db with the supravox as with the
20s 8-10w would be enough.
So a high fs and a high qts sometime not the best answer.
-You get a sharp roll off under the driver fs;
-the lf roll off isn't much better
- you loose efficiency
- you get lower quality bass (a tight bass is very important)
You must compare apples with apples; The Fertin 20s
are 323euros each. Now if you wan silver v.c- carbone spider-
and brass phase plug; then you get to the 450euros.
Does the Supravox all these options for 300euros??
What's BSC?
are 323euros each. Now if you wan silver v.c- carbone spider-
and brass phase plug; then you get to the 450euros.
Does the Supravox all these options for 300euros??
What's BSC?
you are not correct !!!
the 20s at 323€ have fs42 becouse the spider are fiber!! NOT 27
is good? resp.curve
Do not try 😉
BSC=correction network ,so big
bsc
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