I'll endorse that. I didn't see the box pics, didn't run the sim, but this is pretty much exactly what I was going to do. TB46 knows how to design mltl. The port is a bit smaller than the one in my sim so will have slightly more velocity but it should be fine.
A proper high pass filter is a very good idea.
My last sim had a bit different port and maybe a bit different tuning but I was showing 67 watts (19.9V at 5.8 ohms) as the lowest power to high xmax above tuning. A bit different than 11 w. But it doesn't really matter, once it starts sounding bad don't turn the volume up any higher.
If the amp hpf is steep, non defeatable, and set at 20 hz, it's possible that you will never get any decent level of 16 hz bass. That's easy enough to fix, just swap in a different amp. It doesn't have to be a big amp, my sim at 17 mm excursion (more than twice xmax) showed it needed only 300 watts and you really don't want to push it that hard.
Here are some pictures of the homemade bass speaker and the refurbished Allen HC12 speakers.
https://bachonphotos.shutterfly.com/pictures#editPictures:albumId=14
Let me know if these don't post properly.
Bach On
https://bachonphotos.shutterfly.com/pictures#editPictures:albumId=14
Let me know if these don't post properly.
Bach On
Port that puppy and be done with it, imo. I wouldn't worry too much about a high pass filter if the only thing ever hooked up to it is the organ.
If you decide that isn't going to cut the mustard, then start thinking about opening the wallet up for something more powerful, but by far the simplest and only logical first step is going to be a holesaw and a piece of PVC.
If you decide that isn't going to cut the mustard, then start thinking about opening the wallet up for something more powerful, but by far the simplest and only logical first step is going to be a holesaw and a piece of PVC.
Yes, it is for the reasons I posted in my follow-up complete with caveats if the church wasn’t designed for the extra octave along with an example of what’s required once he measures the output of his existing speaker or its published data, which hopefully is accurate.
I was.
Well, let’s see, you stated that “I find that a free slug of air in a port is a MUCH better solution than costly passive radiators every single time”, but to substitute large enough vents in lieu of PRs to get the desired acoustic power @ 16 Hz they would need to be long enough that pipe harmonics would very likely be a problem even in a large space in this ‘properly designed’ system, necessitating they be heavily damped as I previously noted, making it not so ‘properly designed’ for this app.
GM
I have four 15" Ascendant Audio Avalanche drivers (27mm Xmax, 15 Hz Fs, made in the USA) that I bought several years back for a project, but was never able to start it after buying them. It's been forever since I did any simulations, but if I remember correctly, my plans were to house each of them in a large vented enclosure made of Sonotube. Something like 12 or so cubic feet for each woofer, tuned to 14-15 Hz. This would be perfect for your application, and would provide substantial output for your lowest pipe organ notes in a large environment. I'd be willing to let go of all 4 of them for $800. Just thought I'd mention it. Shoot me a PM if you're interested.
I stand to be corrected, but I saw nothing in the manual indicating a FIXED high pass filter on the Crown XLS1000 or XLS1500.
1. You can bypass the crossover circuitry.
2. You can go through the crossover circuitry.
IF YOU UTILIZE THE CROSSOVER CIRCUITRY, you can set the crossover frequency from around 20 hz. to, I believe, as high as 1800 hz.
THEN
You can set the amp for EITHER Lowpass Filter - where input from the signal coming into Channel 1 is sent to both output channels. Only signals below the Crossover point will be sent.
If you set the amp to HIGHPASS Filter - input from Channel 1 will be sent to both output channels. Only signals above the Crossover point will be sent.
In both of those cases, signals to Channel 2 are ignored.
I was disappointed to learn you cannot take the signal from Channel 1 and run it below the crossover point AND run the signal from Channel 2 above the crossover point.
Bach On
'Sounds' like a good deal and for sure in the ball park of what I recommended, though would need the model number or ideally their measured specs to see how they fare and what power requirements are required.
GM
Hello Bach On,
Just a sidebar: Do you mind telling where you had your midrange drivers refoamed (in the HC12s), or did you do it yourself?
Thanks,
-- Jim
That is true, I find ports better than PRs every single time.
In my sim the port length was 60.5 cm (2 feet long), the resonances were outside the passband and pretty benign. Probably not noticeable even without stuffing, especially with a normal crossover point and slope. TB46's port length was considerably shorter than mine, so his resonances are most likely even further up outside the passband.
And by now you should know that when the ports become long enough to cause problems I do the same thing you do - morph the ported box into a reverse taper tl and use driver and port position on the box and VERY LIGHT stuffing inside the box to get a beautiful smooth response. Keeping the VERY LIGHT stuffing well away from the ported end of the box has almost no effect on the lower bass while sucking up all the problem higher frequency resonances.
So do you have any specific problem with the sims I posted or the ones TB46 posted or are you just making a general comment that people sometimes don't design low tuned ported boxes well? If it's the former, please point out the problem(s). If it's the latter I'm not sure why we are even discussing this, it should be obvious that there's lots of bad designs by a lot of bad designers and ports absolutely can be a problem in a bad design.
If there's an $800 driver budget I'd probably go with four of these, 18 inch, 17 hz fs, 22.5 mm published xmax. HT18 18″ Subwoofer | Stereo Integrity
(Despite the published xmax they perform very similarly to Dayton 18 HO which has much less published xmax, but both drivers perform pretty well for the price, this one is currently cheaper.)
Not my favorite company for a lot of reasons but this does seem to be the value leader again now that price has dropped and these probably seriously outperform 15 inch Avalanches. Wiggins has been known to take certain liberties with his xmax spec too.
(Despite the published xmax they perform very similarly to Dayton 18 HO which has much less published xmax, but both drivers perform pretty well for the price, this one is currently cheaper.)
Not my favorite company for a lot of reasons but this does seem to be the value leader again now that price has dropped and these probably seriously outperform 15 inch Avalanches. Wiggins has been known to take certain liberties with his xmax spec too.
Have you mentioned how large the church is ? This may be a huge factor partially because in a smaller venue you may pick up some room gain to help you out. Years ago a small article in The Absolute Sound mentioned that a sealed sub that was flat to 30hz would usually be flat to about 20hz when placed in the typical listening room because of room gain. One cheep thing you may want to try is raising the QTS of that woffer with a high power 2 to 3 ohm resistor between it and the amp. Yea you will lose a lot of power from the amp but it will boost the low bass a great deal.
Wouldn't a 2 ohm resistor that can take a few hundred watts be the size of a beer bottle?
Edit: lol.
Last edited:
First, I replaced the surrounds on those Allen HC12 speakers myself. Got the parts from Speaker Exchange. FYI - the kits for these mid-range speakers are the same as the ones used on the Bose 901 series of speakers.They may be the same speakers - both made by Peerless.
The Sanctuary is about 100 feet long and 75 feet wide with a 30 foot high flat ceiling. There are three sections of wooden pews with 2" thick seat cushions. Walls are plaster with 12 fairly large stained glass windows. The floor is hardwood. There is carpet at the front and the rear of the Sanctuary. Carpet also extends down two aisles, but not beneath the pews. This is a United Methodist Church in Eastern North Carolina, USA.
The choir loft is directly behind the pulpit. The organ is in the choir loft. There are non-working pipes in front of the shades - just for show. I'd say the bottom of the shades is about 9 feet above the floor level. The opening for the shades is roughly 7 feet square. The pipes are in a enclosed room on the other side of the shades.
The organ is an Estey brand. This church was one of the first in our area to have a pipe organ. The purpose of the sound engine and speakers is to add some sounds the organ does not have. It only has one rank of 16' pipes. The lowest pitch on a 16' rank of pipes is 32 hz. The organ also lacks high pitched pipes that give the music a bit more sparkle.
Some facts about pipe organs - just for giggles. This is just very general info.
Organ loft - not all churches have one. If the organ is placed in an area above the height of the congregation, it might be called an organ loft (from "the organ is aloft").
The part you see with the keys and pedals is called the console. It communicates with the pipes. Some organs have exposed working pipes. The volume on these pipes cannot be adjusted while playing. Other pipes may be located in a separate room. This room can be divided into separate chambers. Shades for each chamber may allow the volume heard to be adjusted while the instrument is being played.
For our organ, all pipes are in a single chamber with one set of shades. Air is supplied by an electric blower to fill up a spring loaded wind chest. The air is not highly compressed like a tire. Typical pressures may be in the area of 4 to 8 pounds per square inch. The wind chest mechanically tries to keep the pressure steady. More pipes operating can drain off the air more quickly than just a few pipes playing. If the pressure falls off too much, the pitch of the pipes may begin to sag below pitch.
The pipes sit in separate wooden boxes lined with leather on the inside to prevent air leaks. These are often called receivers. If the organ has a Trumpet, all the trumpet pipes are called a rank of pipes. Some bigger pipes may be so large that more than one receiver is needed to hold all the pipes of that rank.
Most of the receivers are supplied with air at all times. There "buttons" on the console to tell the console what receivers should be active. Some of the buttons may be flip tabs. Or sometimes push/pull knobs - called draw knobs are used. Some organs have draw knobs and tabs.
If I have the Trumpet set to play, playing a key will send a signal to the appropriate pipe. Most modern organs work by having a electro-magnetic solenoid valve beneath each pipe. The valve opens when it gets the signal and air enters the pipe until the valve is closed. The pipes play at full volume when the air enters them. Adjusting the volume for the listener is accomplished by opening or closing the shades on the pipe rooms. These rooms are often called pipe chambers.
Remember that organs of the 15th, 16th, 17th, 18th and 19th century used no electricity. All of this was done mechanically. The church organ was considered very high tech in it's day.
More than you might want to know.
Bach On
The Sanctuary is about 100 feet long and 75 feet wide with a 30 foot high flat ceiling. There are three sections of wooden pews with 2" thick seat cushions. Walls are plaster with 12 fairly large stained glass windows. The floor is hardwood. There is carpet at the front and the rear of the Sanctuary. Carpet also extends down two aisles, but not beneath the pews. This is a United Methodist Church in Eastern North Carolina, USA.
The choir loft is directly behind the pulpit. The organ is in the choir loft. There are non-working pipes in front of the shades - just for show. I'd say the bottom of the shades is about 9 feet above the floor level. The opening for the shades is roughly 7 feet square. The pipes are in a enclosed room on the other side of the shades.
The organ is an Estey brand. This church was one of the first in our area to have a pipe organ. The purpose of the sound engine and speakers is to add some sounds the organ does not have. It only has one rank of 16' pipes. The lowest pitch on a 16' rank of pipes is 32 hz. The organ also lacks high pitched pipes that give the music a bit more sparkle.
Some facts about pipe organs - just for giggles. This is just very general info.
Organ loft - not all churches have one. If the organ is placed in an area above the height of the congregation, it might be called an organ loft (from "the organ is aloft").
The part you see with the keys and pedals is called the console. It communicates with the pipes. Some organs have exposed working pipes. The volume on these pipes cannot be adjusted while playing. Other pipes may be located in a separate room. This room can be divided into separate chambers. Shades for each chamber may allow the volume heard to be adjusted while the instrument is being played.
For our organ, all pipes are in a single chamber with one set of shades. Air is supplied by an electric blower to fill up a spring loaded wind chest. The air is not highly compressed like a tire. Typical pressures may be in the area of 4 to 8 pounds per square inch. The wind chest mechanically tries to keep the pressure steady. More pipes operating can drain off the air more quickly than just a few pipes playing. If the pressure falls off too much, the pitch of the pipes may begin to sag below pitch.
The pipes sit in separate wooden boxes lined with leather on the inside to prevent air leaks. These are often called receivers. If the organ has a Trumpet, all the trumpet pipes are called a rank of pipes. Some bigger pipes may be so large that more than one receiver is needed to hold all the pipes of that rank.
Most of the receivers are supplied with air at all times. There "buttons" on the console to tell the console what receivers should be active. Some of the buttons may be flip tabs. Or sometimes push/pull knobs - called draw knobs are used. Some organs have draw knobs and tabs.
If I have the Trumpet set to play, playing a key will send a signal to the appropriate pipe. Most modern organs work by having a electro-magnetic solenoid valve beneath each pipe. The valve opens when it gets the signal and air enters the pipe until the valve is closed. The pipes play at full volume when the air enters them. Adjusting the volume for the listener is accomplished by opening or closing the shades on the pipe rooms. These rooms are often called pipe chambers.
Remember that organs of the 15th, 16th, 17th, 18th and 19th century used no electricity. All of this was done mechanically. The church organ was considered very high tech in it's day.
More than you might want to know.
Bach On
Oh, a real organ! I don't know why I was thinking you were just making speakers for an electronic organ.
Are you mic-ing the organ and feeding it to the amplifier? If the organ's lowest pipe is 32hz, how are you generating a 16hz note to even feed an amplifier?
In any case, I'm pretty much going to retract everything I've said, there's no way you're going to replicate a real 16hz pipe with one driver that's going to get even close to being able to keep up with other real pipes, imo.
Are you mic-ing the organ and feeding it to the amplifier? If the organ's lowest pipe is 32hz, how are you generating a 16hz note to even feed an amplifier?
In any case, I'm pretty much going to retract everything I've said, there's no way you're going to replicate a real 16hz pipe with one driver that's going to get even close to being able to keep up with other real pipes, imo.
Hi Bach On,
That's a big room, hope you are not shooting for rock concert levels. 🙂
Post #106: "... you cannot take the signal from Channel 1 and run it below the crossover point AND run the signal from Channel 2 above the crossover point."
The manual for the XPS1500 calls the operational mode you are looking for "Crossover Mode", Page 4 Operation Manual. The other mode that might work for you is the "Stereo Bypass Mode", but you will need an external crossover.
You may have to contact the manufacturer to find out how the frequencies below 20Hz area handled. All digital amps have some form of low cut.
Regards,
That's a big room, hope you are not shooting for rock concert levels. 🙂
Post #106: "... you cannot take the signal from Channel 1 and run it below the crossover point AND run the signal from Channel 2 above the crossover point."
The manual for the XPS1500 calls the operational mode you are looking for "Crossover Mode", Page 4 Operation Manual. The other mode that might work for you is the "Stereo Bypass Mode", but you will need an external crossover.
You may have to contact the manufacturer to find out how the frequencies below 20Hz area handled. All digital amps have some form of low cut.
Regards,
I assume that you are talking about port resonance here (no idea what a "pipe harmonic" is), but even so don't see how it applies. We're not talking about wide-range reproduction, but about a primary acoustic source for synthesized signal in the range of 16-64 (or maybe 128?) Hz. It's unlikely that a port resonance even as low as 300Hz. would have any significant effect, and even if it did it would fall in the same category as guitar speaker distortion . . . simply a part of the synthesized sound.
Many of the responses and comments here relate more to "Hi Fi reproduction" than to the OP's need . . . organ speakers are not "reproducers" but part of a sound producing instrument. Certainly there are similarities, and the underlying physics is the same, but the intention, and thus the end product, can and probably should be quite different from a HT "subwoofer", since a different set of requirements and constraints apply. Port resonance may matter for a subwoofer that sees "effects channel" signal up to 3-400Hz., but is not at all an issue in this application . . .
I still don't understand ...this is a physical pipe organ.
How does one add an octave to an air+pipe organ using speakers?
How does one add an octave to an air+pipe organ using speakers?
The OP explains up-thread . . . this is for a synthesized low frequency stop (or stops) in an application where there are either not funds or not space for a new rank of pipes (and blowers etc.) of that size.
The OP has not given enough information about the acoustic space or the loft SPL of the current instrument to give a definitive answer, but the intent is not to "amplify" the entire organ, only to provide the output equivalent of two or three sounding pipes . . . and that is not implausible with (more or less) the current configuration (once it's "fixed" . . . a single driver in a closed box is certainly not going to do it, as already demonstrated).
This really isn't a good idea. You don't get a great deal of bass boost, you get a slightly lower tuning, a big hump an octave or two above tuning and LESS low bass. This box is big enough that the result of adding resistance doesn't look terrible, but in more regular size boxes the effect is usually a lot more pronounced.
This is my last sim (light grey) overlaid with 3 ohms added resistance (dark black). No advantage at all at 16 hz, and it now takes more power to hit the same excursion level. You could raise the tuning to compensate, but 16 hz is the only thing that really matters here, and the resistor doesn't help anything at 16 hz.
An externally hosted image should be here but it was not working when we last tested it.
Yes, these high power resistors are big, expensive and generally not a good idea in speaker applications. If you want a high q, get a high q driver.
If the resistor can't handle the power it's going to start a fire. Adding a 3 ohm resistor to a 5.8 ohm driver is going to result in the resistor soaking up a LOT of power and producing nothing but heat with it.
Ah, ok. I re-read the thread this morning and didn't make out what was going on.
Well, we know the space involved (quite large) and the requirements (octave 0 that can keep up with octave 1).
I don't think a single driver in any box of any configuration is going to do it, unless there's a brick under the back side of the volume pedal. Just based on the visual appearance of the driver and cabinet, the only 16 cycle note you're going to get is the one generated by a voice coil former violently clacking against a backplate.
- Status
- Not open for further replies.