Regarding Directionality
OK, I'm game, Magnetar. If the mid-horn mouth diameter is 12.5" and the throat is 3.65", what profile is the horn you're using with the B&C 6PEV13? Tractrix? LeCleac'h? Or are they all pretty similar when all is said and done? Inquiring minds would like to know. You've mentioned earlier that the low and high pass crossovers are at 350 Hz and 3 kHz, both 4th-order active. Any EQ within that range, or does the rising response pretty much compensate for the horn loading?
If a lower-slope lowpass filter was used, if the B&C data is right, then a 4.7 kHz notch filter looks like it would be a good idea. With a 4th-order crossover it probably wouldn't make difference, particularly if listening off-axis.
I'm guessing it would take a quartet of 6ND410's or Audax PR170M0's to match what the horn/waveguide/6PEV13 is doing.
Magnetar said:
OK, I'm game, Magnetar. If the mid-horn mouth diameter is 12.5" and the throat is 3.65", what profile is the horn you're using with the B&C 6PEV13? Tractrix? LeCleac'h? Or are they all pretty similar when all is said and done? Inquiring minds would like to know. You've mentioned earlier that the low and high pass crossovers are at 350 Hz and 3 kHz, both 4th-order active. Any EQ within that range, or does the rising response pretty much compensate for the horn loading?
If a lower-slope lowpass filter was used, if the B&C data is right, then a 4.7 kHz notch filter looks like it would be a good idea. With a 4th-order crossover it probably wouldn't make difference, particularly if listening off-axis.
I'm guessing it would take a quartet of 6ND410's or Audax PR170M0's to match what the horn/waveguide/6PEV13 is doing.
Attachments
Magnetar mentions in his thread that the use of 2x stack mids (Audax) has its "issues" and that the short horn does the job better. Maybe the horn could still have an advantage over the quads.
I would also like to hear Magnetar on the details of his short horn. 12.5"?
I would myself love a "monocoque" version: a baffle with both with the waveguide for the tweeter and the waveguide for the mid.
I also like Magnetars 5 woofer solution. Very good bass at a very moderate price. I would be happy with 4.
Maybe Lynn could contribute a different tweeter setup and analog "time aligned" and very refined crossovers. It would be a "killer" speaker.
Magnetar: what music do you hear most? At what sound level do you enjoy your music?
I would also like to hear Magnetar on the details of his short horn. 12.5"?
I would myself love a "monocoque" version: a baffle with both with the waveguide for the tweeter and the waveguide for the mid.
I also like Magnetars 5 woofer solution. Very good bass at a very moderate price. I would be happy with 4.
Maybe Lynn could contribute a different tweeter setup and analog "time aligned" and very refined crossovers. It would be a "killer" speaker.
Magnetar: what music do you hear most? At what sound level do you enjoy your music?
Re: Regarding Directionality
I use tractrix horns because I already had them and they sound good. The LeCleac'h is supposed to be better for compression drivers (long horns) because of the flare profile and the mouth. I don't believe it would audibly better with a cone loaded driver in a short horn. Maybe we can get the man himself to comment? you are correct in the crossovers and the lack of eq needed on the mid, highs and bass other than the high pass on the bass to eliminate the bump in the power region in the bass.
I have successfully implemented a first order series network between the mid and treble (so I can use one amp to drive the mid up) at 2.5K - the horn itself is a bandpass filter and in my opinion there is no need to notch out the 4.8k bump at the top of the midrange when using the series network. It's too far down to bother me, if I was using it as a direct radiator it would be a different story and I would rather use a driver that would work without adding parts and circuits to roll it off. You see, I like to keep it simple and want the least amount of passive components between the amp and the driver. I'd rather use a different driver than add complexity that will lower sensitivity or 'kill' something that does not have to exist. I still prefer to multiamp the top end for purer strain free sound.
To start from scratch I would use four 12's , between .5 and .7 QTS, close to the floor in a square with a little eq. Above that would be a 250 Hz short rectangular conical 'waveguide' or 'horn' loaded with that little six inch 18 sound driver or the B&C i am using now - The 250 flare would be better in the lower mid and the crossover would be below 300 - mmore ideal IME- it would however bring the height of the bass mid to around 46 inches though! So where would the treble go and how would you align it with the midrange? Well that would bring us to a horn loaded treble (or the Karlson tube) that could go between the bass and mid sections. My current system uses a smaller mid horn so i can use the treble above the mid - not so with the bigger mid. The little Parts Express round conical horn (like 8 bucks) sounds great and could do the job here..
I explained it pretty well in the other thread, it's a round tractrix horn with a 350 hz flare.
I agree a baffle with both horns integrated would be great!
[/B]
It really depends on my mood or the mood I want to be in! Or for that matter where I want to be transported to or who I want to beam down! An example:
A friend has a very nice local band - here is a cut from his latest CD- His vocals are outstanding, it's high poer emotional music with drive - for thisCD he brought in a string section, choir and brass section!
Colin Dussault's Blues Project! short cut - LISTEN!!!
I agree! Bill could really design a killer mid horn for this project!!!
http://www.acoustic-horn.com/images/HYPEX70.gif
Lynn Olson said:
I use tractrix horns because I already had them and they sound good. The LeCleac'h is supposed to be better for compression drivers (long horns) because of the flare profile and the mouth. I don't believe it would audibly better with a cone loaded driver in a short horn. Maybe we can get the man himself to comment? you are correct in the crossovers and the lack of eq needed on the mid, highs and bass other than the high pass on the bass to eliminate the bump in the power region in the bass.
I have successfully implemented a first order series network between the mid and treble (so I can use one amp to drive the mid up) at 2.5K - the horn itself is a bandpass filter and in my opinion there is no need to notch out the 4.8k bump at the top of the midrange when using the series network. It's too far down to bother me, if I was using it as a direct radiator it would be a different story and I would rather use a driver that would work without adding parts and circuits to roll it off. You see, I like to keep it simple and want the least amount of passive components between the amp and the driver. I'd rather use a different driver than add complexity that will lower sensitivity or 'kill' something that does not have to exist. I still prefer to multiamp the top end for purer strain free sound.
To start from scratch I would use four 12's , between .5 and .7 QTS, close to the floor in a square with a little eq. Above that would be a 250 Hz short rectangular conical 'waveguide' or 'horn' loaded with that little six inch 18 sound driver or the B&C i am using now - The 250 flare would be better in the lower mid and the crossover would be below 300 - mmore ideal IME- it would however bring the height of the bass mid to around 46 inches though! So where would the treble go and how would you align it with the midrange? Well that would bring us to a horn loaded treble (or the Karlson tube) that could go between the bass and mid sections. My current system uses a smaller mid horn so i can use the treble above the mid - not so with the bigger mid. The little Parts Express round conical horn (like 8 bucks) sounds great and could do the job here..
swak said:
I explained it pretty well in the other thread, it's a round tractrix horn with a 350 hz flare.
I agree a baffle with both horns integrated would be great!
[/B]
It really depends on my mood or the mood I want to be in! Or for that matter where I want to be transported to or who I want to beam down! An example:
A friend has a very nice local band - here is a cut from his latest CD- His vocals are outstanding, it's high poer emotional music with drive - for thisCD he brought in a string section, choir and brass section!
Colin Dussault's Blues Project! short cut - LISTEN!!!
pdan said:
I agree! Bill could really design a killer mid horn for this project!!!
http://www.acoustic-horn.com/images/HYPEX70.gif
For the dipole midrange soundstage and low frequency dipole frequency roll-off point, has anyone experimented with the shape of the baffle? Would a high and narrow baffle sound significantly different than a wide and short baffle, or minimum size baffle that just covers the speaker frames like Magnepan's earlier multi-6"? For the lower midrange crossover frequency, could one favorably shape the dispersion pattern by shaping the baffle?
There are a few equations used to estimate how the width and height of the baffle affect the dipole roll-off frequency, but I have not seen much on radiation pattern. Most just use W and L..
Linkwitz baffle 6db freq = 0.17*speedsound/((W+L)/2)
Magnepan, have you experimented with extending your midrange dipole baffle height significantly above the speaker frame?
There are a few equations used to estimate how the width and height of the baffle affect the dipole roll-off frequency, but I have not seen much on radiation pattern. Most just use W and L..
Linkwitz baffle 6db freq = 0.17*speedsound/((W+L)/2)
Magnepan, have you experimented with extending your midrange dipole baffle height significantly above the speaker frame?
Some interesting tid-bits from the Lansing Heritage site. These two excerpts in particular:
This led JBL to pioneer the use of titanium as a diaphragm material in 1982. Titanium is an order of magnitude more resistant to fatigue failures than aluminum. With this new diaphragm, JBL now had compression drivers with exceptional output and extension.
However, it was recognized that there were compromises with the new diaphragms. Titanium does not have the internal damping of aluminum and thus has marginally higher distortion levels. The diamond surrounds, while extending frequency response, do so at the expense of transient response. Further, due to its lower stiffness, titanium goes into breakup at a lower frequency.
This issue of breakup is worth elaboration. Ideally, a dynamic loudspeaker diaphragm should act as a piston, with all points in uniform motion. However, since diaphragms are not infinitely rigid, there will be a condition at which the forces acting upon it cause oscillating deflections resulting in different points on the surface moving in different directions. Under this condition, the diaphragm is said to be in breakup, and there is an attendant increase in distortion. Both aluminum and titanium compression driver diaphragms are in breakup for much of their response. On a large format driver, the breakup modes for aluminum diaphragms occur as low as 7000 Hz, and for titanium diaphragms, as low as 4000 Hz.
And this little point as well:
Another unique feature of this driver is that it does not have a traditional throat. The phase plug terminates at the driver exit. It results in an effective flare rate of 550 Hz. Previously, virtually every compression driver made had a 180 Hz flare rate whose origin dates back to the original AT&T Labs designs from the 1930's. This low rate was necessary to accommodate the low cross-over points used in early two-way loudspeakers. However, this low rate compromised high frequency performance. Given that there was no need for such low frequency output for the 435Be, the flare rate could be optimized to result in a 6 dB drop in second harmonic distortion.
Items I certainly didn't know - that titanium is dominant in prosound due to durability issues more than anything else (!), breakup with titanium starts as low as 4 kHz (!!), and the flare rates in "virtually every" compression-driver phase-plug exits are set to a 180 Hz flare for little more than historical reasons! Who would have thought!
What's more astonishing is that it took more than half-a-century for it to dawn on anyone that maybe, just maybe, the 1935 Westrex/ERPI convention didn't make sense anymore.
This led JBL to pioneer the use of titanium as a diaphragm material in 1982. Titanium is an order of magnitude more resistant to fatigue failures than aluminum. With this new diaphragm, JBL now had compression drivers with exceptional output and extension.
However, it was recognized that there were compromises with the new diaphragms. Titanium does not have the internal damping of aluminum and thus has marginally higher distortion levels. The diamond surrounds, while extending frequency response, do so at the expense of transient response. Further, due to its lower stiffness, titanium goes into breakup at a lower frequency.
This issue of breakup is worth elaboration. Ideally, a dynamic loudspeaker diaphragm should act as a piston, with all points in uniform motion. However, since diaphragms are not infinitely rigid, there will be a condition at which the forces acting upon it cause oscillating deflections resulting in different points on the surface moving in different directions. Under this condition, the diaphragm is said to be in breakup, and there is an attendant increase in distortion. Both aluminum and titanium compression driver diaphragms are in breakup for much of their response. On a large format driver, the breakup modes for aluminum diaphragms occur as low as 7000 Hz, and for titanium diaphragms, as low as 4000 Hz.
And this little point as well:
Another unique feature of this driver is that it does not have a traditional throat. The phase plug terminates at the driver exit. It results in an effective flare rate of 550 Hz. Previously, virtually every compression driver made had a 180 Hz flare rate whose origin dates back to the original AT&T Labs designs from the 1930's. This low rate was necessary to accommodate the low cross-over points used in early two-way loudspeakers. However, this low rate compromised high frequency performance. Given that there was no need for such low frequency output for the 435Be, the flare rate could be optimized to result in a 6 dB drop in second harmonic distortion.
Items I certainly didn't know - that titanium is dominant in prosound due to durability issues more than anything else (!), breakup with titanium starts as low as 4 kHz (!!), and the flare rates in "virtually every" compression-driver phase-plug exits are set to a 180 Hz flare for little more than historical reasons! Who would have thought!
What's more astonishing is that it took more than half-a-century for it to dawn on anyone that maybe, just maybe, the 1935 Westrex/ERPI convention didn't make sense anymore.
LineSource said:
Below the dipole = monopole frequency there is little impact on radiation pattern for flat baffles. The impact becomes greater as the frequency increases. The dipole = monopole frequency is given by 0.1666 x C/(Dequ/2) where Dequ is the equivalent diameter of the bafflle which depends on the baffle shape and position of the driver on the baffle. See http://www.musicanddesign.com/Equivalent_Baffles.html.
At frequencies above the monopole = dipole point baffle shape can have a varied effect, particularly as the driver becomes directional and when there is a loss of symmetry between the front and rear radiation form the driver.
He is talking mostly about large diaphragm large format drivers -Even the highly regarded TAD drivers are in breakup at around 8k - massive breakup - what they use is a special fifth slit on the outer edge of their plug to grab this - that's what gives there drivers a boost in the top.
I like short exit driver with a soft more 'self damping' dome. For large format phenolic 4" or aluminum 3" with mylar surround. For 1" exit the little mylar B&C sounds way too good for it's cost, and again the mylar surround aluminum drivers like Radian and Emilar tend to sound great. There are some phenolic horn tweeters out there too. None of them will work below 3.5 k though.
I am really busy and need to travel this week, if I had time I'd design a 100 by 60 conical (purest wve form but with lower efficiency) waveguide for a six inch driver with a 200 to 250 hz flare- maybe some one else can do this ? One that would be the same width as the bass panel and one that would allow good integration of the treble - A circular entrance transition to rectangular- Maybe make the throat adaptable to smaller/ larger drivers to experiment -
I like short exit driver with a soft more 'self damping' dome. For large format phenolic 4" or aluminum 3" with mylar surround. For 1" exit the little mylar B&C sounds way too good for it's cost, and again the mylar surround aluminum drivers like Radian and Emilar tend to sound great. There are some phenolic horn tweeters out there too. None of them will work below 3.5 k though.
I am really busy and need to travel this week, if I had time I'd design a 100 by 60 conical (purest wve form but with lower efficiency) waveguide for a six inch driver with a 200 to 250 hz flare- maybe some one else can do this ? One that would be the same width as the bass panel and one that would allow good integration of the treble - A circular entrance transition to rectangular- Maybe make the throat adaptable to smaller/ larger drivers to experiment -
If one were doing a 1-piece baffle with both a wavegide for the tweeter and a waveguide for the mid, what material could one use?
My cousin has a small plastic injection company, so I wanted to ask if there is a type of plastic that can be used in a relatively inexpensive mold. Of course the costs would be too high for 1 diy project, but I could probably manage to sell them as well.
My cousin has a small plastic injection company, so I wanted to ask if there is a type of plastic that can be used in a relatively inexpensive mold. Of course the costs would be too high for 1 diy project, but I could probably manage to sell them as well.
Lynn Olson said:
Thanks Lynn. Yeah, that's pretty much true, there may be a lot of images of phantoms at the cinema, but not many acoustical phantom images.
I always sit dead center at the cinema, so that's not the problem - and I've been in some of the best cinemas in world, so that's no the problem either.
Mostly, I think, it has to do with the encoding and decoding of the soundtrack. It's meant for dialog, music is much less important. Even in the discreet channel systems the image pretty much stick the the center. Hard panning left or right is rarely heard, and "soundstage" really isn't there. The "Circle Surround" that Magnatar likes and it's descendant "SRS" are supposed to be better at wide image.
As good as some cinema sound is, it doesn't do the phantom image thing well at all.
I have very little experience with the home multichannel stuff, but IMO THX has been good overall for cinemas. I'll defend it there.* There was, and still is, some god awful cinema sound out there. THX has gone a long way to fix that and to also raise the bar.
FWIW, the high compression rates are used because of the way the digital audio is recorded on the film in DD. Other systems with separate sound don't need the high compression.
Home multichannel I just don't know enough about. Seems pretty gimmicky.
*Disclaimer: I interviewed for Director of Certification at THX in the early 90s, so I'm biased.
I go my start in "real multichannel" back in the 80s at IRCAM and GRM in Paris.
"As good as some cinema sound is, it doesn't do the phantom image thing well at all."
A good home set-up shure will if it is set-up right. Mine can do phantoms easilly. Without that abillity there is no way you could have smooth pans. On well engineered material you can get pans across the front, from front to back or reverse and across the back. You can get 360 pans as well for special effects.
Rob
A good home set-up shure will if it is set-up right. Mine can do phantoms easilly. Without that abillity there is no way you could have smooth pans. On well engineered material you can get pans across the front, from front to back or reverse and across the back. You can get 360 pans as well for special effects.
Rob
I emailed Bill Woods and asked if he could help you with your project (if you wanted to a mid horn) - He replied -
"Hi Mike,
I am swamped at the moment, but here is a test of a exponential mid horn with a
B+C 6nd38 bas-mid. You can also use the B+C mid only 6" ( I forget the number).
The upper end is set by the throat size, which is set by a big magnet, and a
light cone.
You can post this if you wish.
Best, Bill"
So I'm out for a while too - do you want to pursue a mid horn? If so, I can look at it next week.
Bill recently built a system with the little 6"B&C loaded in a bass horn! WOW- 'Best bass driver' - a six inch? I bet it's a killer horn.
http://www.acoustichorn.com/
"Hi Mike,
I am swamped at the moment, but here is a test of a exponential mid horn with a
B+C 6nd38 bas-mid. You can also use the B+C mid only 6" ( I forget the number).
The upper end is set by the throat size, which is set by a big magnet, and a
light cone.
You can post this if you wish.
Best, Bill"
So I'm out for a while too - do you want to pursue a mid horn? If so, I can look at it next week.
Bill recently built a system with the little 6"B&C loaded in a bass horn! WOW- 'Best bass driver' - a six inch? I bet it's a killer horn.
http://www.acoustichorn.com/
An externally hosted image should be here but it was not working when we last tested it.
Fixed Ratio voltage divider
Lynn or anyone HELP
I built the Fixed ratio voltage divider as you described using 5w 20k ohmite resistors . I am using balanced cables throughout the system . I measured the one cable I built to be sure I had constructed it properly. I hooked up just the high end of one of the amps to determine if the hiss was removed. . No luck . I started stacking resistors up to 80k with no improvement. I also have so much gain that I can hear music with my ear to the speaker with the pre amp turned all the way down.. Just to review , have a Bryston BP 25 connected to a Driverack PA to two 3 channel Anthem MCA 30 amps. I will say I was able to remove the hiss when I temporarily hooked up an ATTY Box ( pro attenuator ). In addition, when the amps power up there is a ,DC offset I presume, that sounds about like someone snapping there fingers.
Lynn or anyone HELP
I built the Fixed ratio voltage divider as you described using 5w 20k ohmite resistors . I am using balanced cables throughout the system . I measured the one cable I built to be sure I had constructed it properly. I hooked up just the high end of one of the amps to determine if the hiss was removed. . No luck . I started stacking resistors up to 80k with no improvement. I also have so much gain that I can hear music with my ear to the speaker with the pre amp turned all the way down.. Just to review , have a Bryston BP 25 connected to a Driverack PA to two 3 channel Anthem MCA 30 amps. I will say I was able to remove the hiss when I temporarily hooked up an ATTY Box ( pro attenuator ). In addition, when the amps power up there is a ,DC offset I presume, that sounds about like someone snapping there fingers.
OK, Greg_OH, if it's a balanced XLR connection, there's a different way to attenuate the signal.
1) You need three 10K precision resistor per connector. Add the attenuator to the XLR plug going into the power amplifier input.
2) Solder a 10K resistor in series with Pin 2. (The signal has to flow through the resistor to get to the pin.)
3) Solder another 10K resistor in series with Pin 3. (The signal has to flow through the resistor to get to the pin.)
4) Solder the third 10K resistor directly between Pins 2 and 3.
5) Repeat for the other channel.
You're done.
1) You need three 10K precision resistor per connector. Add the attenuator to the XLR plug going into the power amplifier input.
2) Solder a 10K resistor in series with Pin 2. (The signal has to flow through the resistor to get to the pin.)
3) Solder another 10K resistor in series with Pin 3. (The signal has to flow through the resistor to get to the pin.)
4) Solder the third 10K resistor directly between Pins 2 and 3.
5) Repeat for the other channel.
You're done.
Quick Question
For Mige0, located at a nice place in the Alps. Or maybe it was Salas, in Greece. Sorry if I can't exactly remember the poster.
You mentioned some time ago that a baffle with a slight crease, or bend, in the middle would have a bit wider dispersion than a simple flat baffle. Assuming we're going to use 4 12 or 15-inch drivers in a square configuration, how much of a bend would be desirable - 15 degrees maybe? More? Less?
I've been in communication with a horn designer in the Midwest (well, I guess Colorado is in the Midwest too, come to think of it, we sure get mid-continent weather). Anyway, he's a fan of compression drivers, and has made the interesting recommendation of the Great Plains Audio 390 phenolic-diaphragm compression driver, which has a 1.4" exit and is a modern version of the Altec 290 driver, which covers the range from 300 Hz to 7 kHz.
He recommended a more practical frequency range of 600 Hz to 5 kHz, and used in a 370 Hz Tractrix horn with a mouth size of 11.7", throat of 1.4", and the length is 10.63" deep.
The Great Plains 390 is $360, and it turns out that Great Plains is also making the 416 15-inch driver with an Alnico magnet for $360, or $240 with a ceramic magnet. This driver, or the 515, are apparently an excellent match for the 290/390 compression driver. Altec aficionados say both have excellent midbass and midrange, with the nod going to the 515. I think Great Plains also makes the 515, but I don't know if it's available with an Alnico magnet.
Anyway, a 416 or 515 could be used in the 40 ~ 640 Hz range with no trouble, with an array of Eminence Delta-15LFA's for 100 Hz and lower region. I'm thinking of two flavors here:
1X Altec/GPA 416 or 515, and 2X Delta-15LFA's. All are in parallel, with additional low-pass filtering for the Delta-15LFA's. Triad-pattern mounting, the two Delta-15LFA's adjacent to the floor, and the Altec/GPA 416 or 515 above and between the Delta-15LFA's.
- or -
2X Altec/GPA 416 or 515, and 2X Delta-15LFA's. In series-parallel, with similar drivers in series, and the Delta-15LFA's additionally low-passed around 100 Hz. Square array, with the Altec/GPA's on one side (the inside), and the Delta-15LFA's on the other side (the outside).
Will be finding out more about the 290/390 phenolic-diaphragm compression driver combined with the 416 or 515 driver. Usually, the early rolloff of a phenolic diaphragm is a disadvantage, but since I want a 3-way system anyway, the early rolloff is an advantage, not a disadvantage.
For the HF, a small horn + CD is practical and inexpensive, but I'm going to be using the double-high RAAL. I plan to use a custom autoformer to match the mid and HF efficiencies, but will trim the system in with a discrete-resistor L-Pad first.
For Mige0, located at a nice place in the Alps. Or maybe it was Salas, in Greece. Sorry if I can't exactly remember the poster.
You mentioned some time ago that a baffle with a slight crease, or bend, in the middle would have a bit wider dispersion than a simple flat baffle. Assuming we're going to use 4 12 or 15-inch drivers in a square configuration, how much of a bend would be desirable - 15 degrees maybe? More? Less?
I've been in communication with a horn designer in the Midwest (well, I guess Colorado is in the Midwest too, come to think of it, we sure get mid-continent weather). Anyway, he's a fan of compression drivers, and has made the interesting recommendation of the Great Plains Audio 390 phenolic-diaphragm compression driver, which has a 1.4" exit and is a modern version of the Altec 290 driver, which covers the range from 300 Hz to 7 kHz.
He recommended a more practical frequency range of 600 Hz to 5 kHz, and used in a 370 Hz Tractrix horn with a mouth size of 11.7", throat of 1.4", and the length is 10.63" deep.
The Great Plains 390 is $360, and it turns out that Great Plains is also making the 416 15-inch driver with an Alnico magnet for $360, or $240 with a ceramic magnet. This driver, or the 515, are apparently an excellent match for the 290/390 compression driver. Altec aficionados say both have excellent midbass and midrange, with the nod going to the 515. I think Great Plains also makes the 515, but I don't know if it's available with an Alnico magnet.
Anyway, a 416 or 515 could be used in the 40 ~ 640 Hz range with no trouble, with an array of Eminence Delta-15LFA's for 100 Hz and lower region. I'm thinking of two flavors here:
1X Altec/GPA 416 or 515, and 2X Delta-15LFA's. All are in parallel, with additional low-pass filtering for the Delta-15LFA's. Triad-pattern mounting, the two Delta-15LFA's adjacent to the floor, and the Altec/GPA 416 or 515 above and between the Delta-15LFA's.
- or -
2X Altec/GPA 416 or 515, and 2X Delta-15LFA's. In series-parallel, with similar drivers in series, and the Delta-15LFA's additionally low-passed around 100 Hz. Square array, with the Altec/GPA's on one side (the inside), and the Delta-15LFA's on the other side (the outside).
Will be finding out more about the 290/390 phenolic-diaphragm compression driver combined with the 416 or 515 driver. Usually, the early rolloff of a phenolic diaphragm is a disadvantage, but since I want a 3-way system anyway, the early rolloff is an advantage, not a disadvantage.
For the HF, a small horn + CD is practical and inexpensive, but I'm going to be using the double-high RAAL. I plan to use a custom autoformer to match the mid and HF efficiencies, but will trim the system in with a discrete-resistor L-Pad first.
So that's three possible midranges: a vertically stacked pair of pro-monitor 6" drivers, like the 6NDA410's or Audax PR170M0's, Magnetar's recommended mid-horn with the B&C 6PEV13 cone driver, or the Altec/GPA with the 290/390 (or Radian 745P if you prefer the sound of aluminum diaphragms).
Crossover points are a little different depending on which is chosen. Since this is an active crossover and the rough prototyping will be done with a prosound EQ/crossover, this should be a matter of turning the knobs, measuring, and listening.
I'm not necessarily committed-in-advance to any of these. It looks very much like I'll be trying all three flavors come January, February, and March. Technically, the cone drivers should have the quickest decay from an impulse, and most likely the flattest response, but the horns should win hands down on lowest IM distortion and most effortless dynamic range.
Crossover points are a little different depending on which is chosen. Since this is an active crossover and the rough prototyping will be done with a prosound EQ/crossover, this should be a matter of turning the knobs, measuring, and listening.
I'm not necessarily committed-in-advance to any of these. It looks very much like I'll be trying all three flavors come January, February, and March. Technically, the cone drivers should have the quickest decay from an impulse, and most likely the flattest response, but the horns should win hands down on lowest IM distortion and most effortless dynamic range.
Whaaaaat? Can we believe what we're reading?
Lynn Olsen wants to use a 515 or a 416 for the bass? And a horn and compression driver for the mid - with an Altec style driver to boot? How can this be? We're talking West Coast sound, here. Horn colorations. Heavens!
Someone please alert the mods. Cal, Dave, Al, Sy? Can you check to see who has hacked Lynn's account?
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