The CTS/Motorola piezos are still available.
CTS Tweeters, High Frequency Tweeters and Horns- CTS formerly Motorola for good quality and cost effective systems. CTS speaker upgrades. CTS tweeters here.
http://www.martinsoundpro.com/pdfs/catalog08_color_drivershornstweeters.pdf
Piezo Source - Products listing
CTS Tweeters, High Frequency Tweeters and Horns- CTS formerly Motorola for good quality and cost effective systems. CTS speaker upgrades. CTS tweeters here.
http://www.martinsoundpro.com/pdfs/catalog08_color_drivershornstweeters.pdf
Piezo Source - Products listing
They don't work all that well unless they do have some additional XO componenets... running them down to where they XO naturally is what gave them their bad rep.
planet_10 hifi
dave
hello.
i make some experiments with a fullrange (fr10) and a tiny dome tweeter (sc5).
but this tweeter is built into the backside of the box (aside the midline,not symmetric).this does not enhance the sound volume (on front axis) but gives a better polar diagram and fine details solution ........and the "room" is anyhow different...............
tweeter xover : 1uf mkt - 1ohm res - tweeter 8ohm.
no xover at the fr (blue line in the sim).
greetings
i make some experiments with a fullrange (fr10) and a tiny dome tweeter (sc5).
but this tweeter is built into the backside of the box (aside the midline,not symmetric).this does not enhance the sound volume (on front axis) but gives a better polar diagram and fine details solution ........and the "room" is anyhow different...............
tweeter xover : 1uf mkt - 1ohm res - tweeter 8ohm.
no xover at the fr (blue line in the sim).
greetings
Attachments
Hello mjf,
i used that trick too in my fullrange dipole line arrays.
A (super) tweeter filling the polar dispersion in those
angles wich are neglected by the fullranger solves
the problem at its root.
I would bet, that also your "sweet spot" is wider now and
the speaker does not sound "dull" anymore when you listen
at greater distance ?
Kind regards
i used that trick too in my fullrange dipole line arrays.
A (super) tweeter filling the polar dispersion in those
angles wich are neglected by the fullranger solves
the problem at its root.
I would bet, that also your "sweet spot" is wider now and
the speaker does not sound "dull" anymore when you listen
at greater distance ?
Kind regards
So is it better to have the helper tweeter firing backwards rather than forwards?
Interesting!
I am going to be running my FR OB. I was thinking of supplimenting the energy above 6K with a forward firing Seas 1.5" dome, but I have also bought a pair of Saba 4" Greencones on ebay that could be run OB - will need to see how these sound compared with the Seas.
I I run the Seas firing backwards, I would connect it with inverse polarity so that it summed in phase with the rear wave?
Colin - you can buy 6 of them in an array box for not much (put some little FR drivers in when you steal the tweeters)
SOUNDLAB|P115CP|PA CABINET SPEAKER, TWEETER ARRAY | CPC
Most of them are less than £5 each if you wanted to mess around.
I've always thought tweeters were most efficient in any given speaker cabinet, but apparently not. I had some cheap car tweeters lying around, which failed to keep up with my FRS8Ms in terms of volume (wired in parallel, cap in series). This surprised me...
Chris
SOUNDLAB|P115CP|PA CABINET SPEAKER, TWEETER ARRAY | CPC
Most of them are less than £5 each if you wanted to mess around.
I've always thought tweeters were most efficient in any given speaker cabinet, but apparently not. I had some cheap car tweeters lying around, which failed to keep up with my FRS8Ms in terms of volume (wired in parallel, cap in series). This surprised me...
Chris
backward "filler" tweeter in fullrange OB
Yes, that would be the proper way if you want an FR OB with a rear
"filler" tweeter (the term was chosen by a friend of mine, as he
auditioned my OBs and i think it hits ...) .
To have acoustic centers of tweeter and the rear side
of the FR cone in the same plane is preferable and should be easy to
do with an OB.
A fullranger usually has a falling frequency response according to shape
(magnet size) and dimension on the rear side. Typical models drop
above 1..3 Khz. The rear tweeter fills the missing backward radiation.
In fact there will be a crossover frequency where the tweeter
will contribute the same sound pressure as the fullrangers rear side,
even though the electrical low pass filter for the FR is omitted.
This technique is interesting if the fullranger has good presence and
brillance to the front. Btw. there is an early OB design from Wharfdale with
a tweeter firing to the ceiling from the fifties. That variant adresses
the same Problem.
If your fullranger has low brillance to the front, and the rear walls in your
room are highly damped (heavy curtains e.g.) a backward tweeter
may not be a good solution.
If implemented right, the result could be a dipole radiator with
fairly frequency independent directivity and symmetric radiation
between front and rear side.
With my own OB design i am very happy, but it uses also equalization
to boost the brillance region of the fullrangers, which affects mainly
the brillance radiated to the front.
Kind regards
Yes, that would be the proper way if you want an FR OB with a rear
"filler" tweeter (the term was chosen by a friend of mine, as he
auditioned my OBs and i think it hits ...) .
To have acoustic centers of tweeter and the rear side
of the FR cone in the same plane is preferable and should be easy to
do with an OB.
A fullranger usually has a falling frequency response according to shape
(magnet size) and dimension on the rear side. Typical models drop
above 1..3 Khz. The rear tweeter fills the missing backward radiation.
In fact there will be a crossover frequency where the tweeter
will contribute the same sound pressure as the fullrangers rear side,
even though the electrical low pass filter for the FR is omitted.
This technique is interesting if the fullranger has good presence and
brillance to the front. Btw. there is an early OB design from Wharfdale with
a tweeter firing to the ceiling from the fifties. That variant adresses
the same Problem.
If your fullranger has low brillance to the front, and the rear walls in your
room are highly damped (heavy curtains e.g.) a backward tweeter
may not be a good solution.
If implemented right, the result could be a dipole radiator with
fairly frequency independent directivity and symmetric radiation
between front and rear side.
With my own OB design i am very happy, but it uses also equalization
to boost the brillance region of the fullrangers, which affects mainly
the brillance radiated to the front.
Kind regards
Hi Oliver,
Yes, when I thought about it, it made perfect sense. The back wave from the FR will be much reduced in the high frequencies, as the are effectively horn loaded from the front.
If I put the tweeter on the front, I would be bringing it in at around 6K, but I would have difficulty getting it to integrate with the FR. Putting it on the back would allow me to bring it in around 3K with higher output, and with less risk of destroying the FR's amazing coherence.
I thought about the top firing approach, but surely there are phase issues with the rear energy being out of phase with the back wave from the FR, or does this not matter in the far field?
My FR is the Supravox 215 EXC which is pretty flat out to 6K, both on axis and at 30 deg. At 60 deg, it droops at around 2K.
Above 6K, it is -6 db on axis, -12 db at 30 deg and -15 at 60 deg. It is pretty flat (for a FR) all the way to 20K.
I suspect the rear firing tweeter will work best, but I will not know until I have tried it.
My OB is going to be a little different in that I will be using a fairly small baffle, sitting on top of a Vented bass box. Also I am thinking of using heavy 1' felt accross the baffles to absorb the excessive midrange projected by the baffle step. I am hoping that with experimentation that I can get a more even forward firing power response.
Thanks Oliver.
Kind Regards
David
Yes, when I thought about it, it made perfect sense. The back wave from the FR will be much reduced in the high frequencies, as the are effectively horn loaded from the front.
If I put the tweeter on the front, I would be bringing it in at around 6K, but I would have difficulty getting it to integrate with the FR. Putting it on the back would allow me to bring it in around 3K with higher output, and with less risk of destroying the FR's amazing coherence.
I thought about the top firing approach, but surely there are phase issues with the rear energy being out of phase with the back wave from the FR, or does this not matter in the far field?
My room is fairly well damped with heavy curtains and acoustic absorbing panels. However, they are mainly down the sides of the room. The rear has bookshelves and CD racks.
My FR is the Supravox 215 EXC which is pretty flat out to 6K, both on axis and at 30 deg. At 60 deg, it droops at around 2K.
Above 6K, it is -6 db on axis, -12 db at 30 deg and -15 at 60 deg. It is pretty flat (for a FR) all the way to 20K.
I suspect the rear firing tweeter will work best, but I will not know until I have tried it.
My OB is going to be a little different in that I will be using a fairly small baffle, sitting on top of a Vented bass box. Also I am thinking of using heavy 1' felt accross the baffles to absorb the excessive midrange projected by the baffle step. I am hoping that with experimentation that I can get a more even forward firing power response.
Thanks Oliver.
Kind Regards
David
rear tweeters
Hi David,
i think what is basically achieved with a rear filler tweeter is
making "copies" of the direct sound bouncing from the walls
(side, rear) more similar to the direct sound in spectral energy
distribution. IMO in that way the speaker/room system draws
less attention to itself, because things "fit" together and
our hearing system is happy to relax.
Nevertheless i would prefer a solution with phase
issues minimized (rear tweeter in phase with backwave).
As you said before, the goal is to keep the homogeneity of
a good fullrange system. The price to pay for "sonic coherence
by using a fullranger" is normally a lack of acoustic power
radiated towards higher frequencies, since the radiation angle
of the fullranger narrows with frequency.
The rear tweeter compensates that partially, but with good
subjective results IMO. Personally i had good experience with
a "less is more" approach. I did not turn around the speakers
180 degrees and adjustet the tweeter to produce a flat on axis
response ... since the tweeter would then radiate much more power
in the crossover region than the fullranger because of its
wider dispersion.
I rather walked around in the room and asked myself
"does it sound approximately the same everywhere".
That led to a lower voltage level for the tweeter, than
in a conventional 2-Way approach, i found a rising voltage towards
the brillance region preferable: Most tweeters will also start to
beam above some frequency (falling acoustic power radiation),
and what we want is a flat power spectrum in the reverberant
field.
btw i did go so far to mimic the higher backward directivity
of the fullranger in the crossover region by using two dome
tweeters row ciruited, one of them bridged by a capacitor to
have a single tweeter at the top.
Since my line array has pronounced directivity, that seemed
to be a good solution. I cannot hear the backward tweeters as
a distinct sound source, but they help to keep the sonic impression
present and brilliant even at larger listening distances in the
whole room, which is pretty unusual when using fullrangers.
Nevertheless what i hear is the homogeneity of the fullrangers,
it does not sound like multiway.
Like to hear from your experiences, since every environment
(and taste) is different ...
Cheers
Hi David,
i think what is basically achieved with a rear filler tweeter is
making "copies" of the direct sound bouncing from the walls
(side, rear) more similar to the direct sound in spectral energy
distribution. IMO in that way the speaker/room system draws
less attention to itself, because things "fit" together and
our hearing system is happy to relax.
Nevertheless i would prefer a solution with phase
issues minimized (rear tweeter in phase with backwave).
As you said before, the goal is to keep the homogeneity of
a good fullrange system. The price to pay for "sonic coherence
by using a fullranger" is normally a lack of acoustic power
radiated towards higher frequencies, since the radiation angle
of the fullranger narrows with frequency.
The rear tweeter compensates that partially, but with good
subjective results IMO. Personally i had good experience with
a "less is more" approach. I did not turn around the speakers
180 degrees and adjustet the tweeter to produce a flat on axis
response ... since the tweeter would then radiate much more power
in the crossover region than the fullranger because of its
wider dispersion.
I rather walked around in the room and asked myself
"does it sound approximately the same everywhere".
That led to a lower voltage level for the tweeter, than
in a conventional 2-Way approach, i found a rising voltage towards
the brillance region preferable: Most tweeters will also start to
beam above some frequency (falling acoustic power radiation),
and what we want is a flat power spectrum in the reverberant
field.
btw i did go so far to mimic the higher backward directivity
of the fullranger in the crossover region by using two dome
tweeters row ciruited, one of them bridged by a capacitor to
have a single tweeter at the top.
Since my line array has pronounced directivity, that seemed
to be a good solution. I cannot hear the backward tweeters as
a distinct sound source, but they help to keep the sonic impression
present and brilliant even at larger listening distances in the
whole room, which is pretty unusual when using fullrangers.
Nevertheless what i hear is the homogeneity of the fullrangers,
it does not sound like multiway.
Like to hear from your experiences, since every environment
(and taste) is different ...
Cheers
Last edited:
My current speaker is an Oskar Heil Syrinx. It uses an AMT type tweeter on top which is a dipole. The back radiation did not bother me in my previous apartments but in my new flat it does. They are now backed to the dining area and they sound much better with a piece of felt covering the back of the AMT. What I am trying to say is that back firing or dipole tweeters might be very room sensitive.
I am more interested in the idea of an omni.
How about a supertweeter like omni-harmonizer from Mark & Daniel?
Would it match a FR on OB? How would an omni work good with a beaming FR?
I think one can build his own omni harmonizer using the supertweeter from M&D.
Thinking of a martini glass.
I am more interested in the idea of an omni.
How about a supertweeter like omni-harmonizer from Mark & Daniel?
Would it match a FR on OB? How would an omni work good with a beaming FR?
I think one can build his own omni harmonizer using the supertweeter from M&D.
Thinking of a martini glass.
I would put in in a different way:
Every speaker which has frequency dependent disconituities
in its polar dispersion pattern will behave room sensitive.
I would estimate the syrinx changes its pattern
from omni (bass to lower midrange)
to upward facing kardioid (upper midrange)
to dipole (1Khz and above)
That change does happen in a critical bandwidth of hearing,
where balance between upper midrange/nasal region and presence
is easily destroyed by changes of a few decibels of sound pressure.
In the crossover region the frequency response will differ very much
between front and rear of the speaker.
(How does the original speaker sound when rotated 180 degrees?)
Furthermore if placed near a rear wall, there will be excessive
comb filtering. That speaker can only work IMO when placed
freely or at least with a rear wall which has high absorption.
There will be only a small range of listening distances, where
the speaker can sound somewhat like balanced, becauce the
directionality is frequency dependent. Balance between direct
and reflected sound will differ with frequency and listening distance.
I would bet, it is a "sweet spot" speaker which cannot be made
work in some rooms at all.
A fullrange dipole speaker will not suffer from that problems,
but in fact has to pe placed at least 1-1.5 m from rear walls.
I agree that placed near walls an omni source will be more benign.
Recently i moved with my dipole 08 design and the current room
is very different from the former. There are naked walls on the rear
and to the sides, which werè not there in my old room.
The only thing i had to adjust was the subwoofer level ...
Everything else was balanced as before. But i have to admit,
that i keep distance to the walls, otherwise a fullrange dipole
would not even produce bass.
Kind Regards
Last edited:
I made up my prototype baffles for my mids and tweeters.
First I tried the Supravox 215 on its own, to find that it is way down in the top end, with a baffle peak around 700Hz. I put 1/2" F11 felt around it which helped, but really had to put a broad notch filter in to make it listenable. Even then. it was way too dull.
Next up was the tweeter added from 3KHz rear firing out of phase. This did help a bit, but I found that the rear wave sounded more correct that the front wave that still sounded very dull.
I have now put the tweeter in the front in phase from about 6KHz. This now sounds a lot better balanced, but I suspect that the mid is still slightly hot and may need padding down by a db or 2.
First I tried the Supravox 215 on its own, to find that it is way down in the top end, with a baffle peak around 700Hz. I put 1/2" F11 felt around it which helped, but really had to put a broad notch filter in to make it listenable. Even then. it was way too dull.
Next up was the tweeter added from 3KHz rear firing out of phase. This did help a bit, but I found that the rear wave sounded more correct that the front wave that still sounded very dull.
I have now put the tweeter in the front in phase from about 6KHz. This now sounds a lot better balanced, but I suspect that the mid is still slightly hot and may need padding down by a db or 2.
Hi Oliver,
Yes it was, and ultimately the solution may be to have 2 tweeters as well as the full range!
Regards
David
A further update on this:
I ended up padding the FR down with a 1.7 Ohm resistor. The tweeter is front firing, but is brought in 1st order at 10K - anything lower than that, and it ruined the coherence of the FR. I also tried adding a rear firing tweeter, but that just created a mess - I thing the frequency power response may have been more right, but all the magic went out the window.
I ended up padding the FR down with a 1.7 Ohm resistor. The tweeter is front firing, but is brought in 1st order at 10K - anything lower than that, and it ruined the coherence of the FR. I also tried adding a rear firing tweeter, but that just created a mess - I thing the frequency power response may have been more right, but all the magic went out the window.
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