MemX,
I have conducted experiments with slot port bass reflex cabinets and found the tuning (Fb) varied less than 1 Hz with the slot on the floor, vertical to the floor, or 2-3 feet from the floor. The difference in Fb was so slight as to be immaterial.
Art
Ben,
I connected some of the speakers last night. And I can absolutely say that the box makes a significant improvement in the total sound. I hope to do further testing today and tomorrow. I'm just testing two HC12s with the bass speaker. This will be in the speaker chamber. Can't do any practical testing in the Sanctuary until we get the large pipes out of the opening into the pipe chamber.
But it seems quite likely that we will need more bass drivers to adequately project the bass sounds out into the Sanctuary. I've been hearing that from most people who have contributed to this thread. That's why the HT18 was ordered. I'm not yet buying lumber. But I am trying to consider the options.
I'm sorry my pace is too slow. But I'm doing the best I can.
Bach On
I connected some of the speakers last night. And I can absolutely say that the box makes a significant improvement in the total sound. I hope to do further testing today and tomorrow. I'm just testing two HC12s with the bass speaker. This will be in the speaker chamber. Can't do any practical testing in the Sanctuary until we get the large pipes out of the opening into the pipe chamber.
But it seems quite likely that we will need more bass drivers to adequately project the bass sounds out into the Sanctuary. I've been hearing that from most people who have contributed to this thread. That's why the HT18 was ordered. I'm not yet buying lumber. But I am trying to consider the options.
I'm sorry my pace is too slow. But I'm doing the best I can.
Bach On
Hi Bach On,
Good to hear that you were able to listen to the Big Box w/ two HC12s, and that the result is promising. The second subwoofer together with the change to the SI HT18s should give you the volume you need.
I fleshed out your geometry from Post #556 to get a feel for the available volume; see attached (What looks like a drawing is really just a sketch w/ notes. You'll have to figure out how to build this thing, and how to get it into the loft. You may have to build that in place, and provide for a removable driver baffle. Don't forget some protective grill, or so, for the driver(s).)
I also ran some more simulations.
Regards,
P.S.: Your pace is just fine.
Good to hear that you were able to listen to the Big Box w/ two HC12s, and that the result is promising. The second subwoofer together with the change to the SI HT18s should give you the volume you need.
I fleshed out your geometry from Post #556 to get a feel for the available volume; see attached (What looks like a drawing is really just a sketch w/ notes. You'll have to figure out how to build this thing, and how to get it into the loft. You may have to build that in place, and provide for a removable driver baffle. Don't forget some protective grill, or so, for the driver(s).)
I also ran some more simulations.
Regards,
P.S.: Your pace is just fine.
Attachments
Hi DrDyna,
I agree, it all looks better with the SI HT18. They seem to like from ~ 8 to 12 ft^3 in a vented enclosure, w/ the duct as large as possible. I have simulated them w/ the T/S from the manufacturer (for the other model), and the T/S from data-bass.com. Some difference, but not enough to talk about. To get high SPL @ low frequencies we just need to move some air. Oh well.
Regards,
I agree, it all looks better with the SI HT18. They seem to like from ~ 8 to 12 ft^3 in a vented enclosure, w/ the duct as large as possible. I have simulated them w/ the T/S from the manufacturer (for the other model), and the T/S from data-bass.com. Some difference, but not enough to talk about. To get high SPL @ low frequencies we just need to move some air. Oh well.
Regards,
Sounds like progress. I'm just offering my little thoughts to keep you on the path (instead of in the clouds).
Next step is to get a bit more analytic about "makes a significant improvement....". Makes the soundscape bigger (and more organ-like?), louder (but not loud enough?), lower (compared to what?), and so on. Depending on your answers, you'd be heading in different directions hereafter.
Don't think of theorizing, let alone cutting wood, until you have a good sense of where you are with what you have. You can't figure which way to go until you know where you are. You are very lucky to have a solid starting point.
Here's my guess: your speaker is adding grand sounding volume in the 40-90 Hz range which most ears consider great organ sound* and that's what you want more of. You can watch what it is a mic is picking up using the real-time analyzer of REW - just click the mouse and you'll immediately see a cross-section in frequencies as the music plays. Chasing 64 foot pipes is noble but maybe a pipe dream. Maybe you'll have vast pride adding ooomph with a speaker not that low.
Ben
*I've been listening to my new #3 Montreal Audio Society test record with a few women singers accompanied by super, extra, profoundly extra-low double-bass plucked solos. Ummm, yummy low. But the RTA of the electric signal never lies: pretty much 70-90 Hz with rare and barely hearable scraps lower now and then.
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I went yesterday afternoon to do some setup and begin experimenting. I simply connected one pair of HC12 speakers and the bass box. I played organ music and begin to experiment with the sound measurement equipment and software I bought. (This runs under Windows. I’m not sure if they have anything for the Mac crowd.) The software and equipment are new to me, so I’m learning. Any measurements don't mean anything if I'm not doing it right, so anything I post must be viewed with that in mind. The software is TrueRTA. It is freeware for versions with fewer features. But I bought the upgraded package to have those features ($99). It comes with a minimalist help system, so I’m feeling my way along with it. Here’s a link for it, if you’re interested.
TrueRTA Audio Spectrum Analyzer Download Page
The calibrated mike is the Dayton EMM-6 (about $45), bought from Parts Express. (I also downloaded the calibration software from the Dayton
site.) It plugs into a box for Phantom Power and into my computer by USB.
I have RCA splitters and patch cables on the outputs of the CD Player (Tascam). One stereo pair goes to the HC12s with 16 gauge cable. One channel goes to the bass speaker. I didn't get the other channel connected for the initial experimenting.
Remember that the HC12s are facing the congregation. Currently, there are large wooden pipes right in front of them. Imagine speakers pointing to a wall. I pulled them back about 3 inches to create a gap for a bit more sound to come out. But they are restricted by their position. And everything is so tight in there that I can’t turn them. The bass speaker is positioned so the drivers are facing the sharp corner to the right of the door. The bass cabinet is on 3 inch feet which allows unrestricted activity from the port.
I have one of the Crown XLS1000 amps set to bypass the crossover system. It powers the two HC12s. It is running at 8 ohms - that's a capacity of 225 watts per channel RMS.
The Crown XLS1500 amp was set for a lowpass filter using a crossover of 270 Hz. The crossover can be adjusted. I did some experimenting to attempt to find a sweet spot. The lowpass filter takes ONE channel of the input and sends the filtered signal to both output channels. Thus, the 2nd channel input is offline. (FYI: Crown now has a newer models in the XLS series that allows one channel to do lowpass and the other channel to do highpass. It wasn't available when we bought ours.)
That means the bass speaker is getting some of the same signals as at least one of the HC12s. It just filters out those above 270 Hz. But there is some overlap between the crossover point and the lower limit of the HC12 woofers - which appears to be roughly 32 Hz. But there is some volume rolloff below 40 Hz.
We will also have a separate HC12 speaker (if space allows) that will run through another XLS1000 set for highpass filter. It will take the opposite channel of the pedal outputs from the bass speaker. I'll do th
I want to repeat this: the Artisan sound engine has 8 outputs, divided into four stereo pairs. The software allows digital sounds to be routed to any of those 8 channels. That is not the case with what I’m currently doing. The CD player only has a 2 channel stereo output, as do the CDs. So splitting the signals and sending them to separate amps results in some duplication of signals being sent to the speakers. I anticipate that some sounds will overlap and be duplicated in area of 40 to 270 Hz. A woofer on a HC12 and the bass speaker will be playing the same sounds. So they will probably sound louder in that particular area of the sonic spectrum. That won’t be the case when everything is connected via the sound engine. But I can’t duplicate that now.
Here's a spectrum analysis on the final chord of the Toccata and Fugue in D Minor by Bach.
I also played some sine waves to measure output.
Here - for perspective - is a 85 Hz. sine wave being played.
And here is one at 21 Hz. - all settings the same:
That's my first stab at using the software and equipment for measurement. I'm open to all sage observations.
Bach On
TrueRTA Audio Spectrum Analyzer Download Page
The calibrated mike is the Dayton EMM-6 (about $45), bought from Parts Express. (I also downloaded the calibration software from the Dayton
site.) It plugs into a box for Phantom Power and into my computer by USB.
I have RCA splitters and patch cables on the outputs of the CD Player (Tascam). One stereo pair goes to the HC12s with 16 gauge cable. One channel goes to the bass speaker. I didn't get the other channel connected for the initial experimenting.
Remember that the HC12s are facing the congregation. Currently, there are large wooden pipes right in front of them. Imagine speakers pointing to a wall. I pulled them back about 3 inches to create a gap for a bit more sound to come out. But they are restricted by their position. And everything is so tight in there that I can’t turn them. The bass speaker is positioned so the drivers are facing the sharp corner to the right of the door. The bass cabinet is on 3 inch feet which allows unrestricted activity from the port.
I have one of the Crown XLS1000 amps set to bypass the crossover system. It powers the two HC12s. It is running at 8 ohms - that's a capacity of 225 watts per channel RMS.
The Crown XLS1500 amp was set for a lowpass filter using a crossover of 270 Hz. The crossover can be adjusted. I did some experimenting to attempt to find a sweet spot. The lowpass filter takes ONE channel of the input and sends the filtered signal to both output channels. Thus, the 2nd channel input is offline. (FYI: Crown now has a newer models in the XLS series that allows one channel to do lowpass and the other channel to do highpass. It wasn't available when we bought ours.)
That means the bass speaker is getting some of the same signals as at least one of the HC12s. It just filters out those above 270 Hz. But there is some overlap between the crossover point and the lower limit of the HC12 woofers - which appears to be roughly 32 Hz. But there is some volume rolloff below 40 Hz.
We will also have a separate HC12 speaker (if space allows) that will run through another XLS1000 set for highpass filter. It will take the opposite channel of the pedal outputs from the bass speaker. I'll do th
I want to repeat this: the Artisan sound engine has 8 outputs, divided into four stereo pairs. The software allows digital sounds to be routed to any of those 8 channels. That is not the case with what I’m currently doing. The CD player only has a 2 channel stereo output, as do the CDs. So splitting the signals and sending them to separate amps results in some duplication of signals being sent to the speakers. I anticipate that some sounds will overlap and be duplicated in area of 40 to 270 Hz. A woofer on a HC12 and the bass speaker will be playing the same sounds. So they will probably sound louder in that particular area of the sonic spectrum. That won’t be the case when everything is connected via the sound engine. But I can’t duplicate that now.
Here's a spectrum analysis on the final chord of the Toccata and Fugue in D Minor by Bach.
I also played some sine waves to measure output.
Here - for perspective - is a 85 Hz. sine wave being played.
And here is one at 21 Hz. - all settings the same:
That's my first stab at using the software and equipment for measurement. I'm open to all sage observations.
Bach On
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What's needed for comparison is one of your 16' pipes sounding, measured in the same position. If you're getting similar loudness from the electronic rank(s) the rest is just cleaning up the details . . .
The other question, of course, is do you like the voicing and could you mistake it for "real" . . .
The other question, of course, is do you like the voicing and could you mistake it for "real" . . .
Sad but true about REW. If BachOn used that he could save the files and we could do a bit of analysis.
But...
Nice first measurements. You have clearly identifiable measurement points there.
dewardh is correct in the matching idea. But I think everyone knows and understands this.
It will have to wait a little while.
Keep on trucking sir. This is looking pretty good.
How far away are you measuring?
But...
Nice first measurements. You have clearly identifiable measurement points there.
dewardh is correct in the matching idea. But I think everyone knows and understands this.
It will have to wait a little while.
Keep on trucking sir. This is looking pretty good.
How far away are you measuring?
Dwardh - I'll try to measure some of the pipes in the next few days.
I just downloaded REW. I'll see what - if anything - I can do. What exactly should I try to post?
Mark - the mike was a foot away from the nearest HC12 and inches away from the rear of the bass box. I'm listening through the access doorway from about 9 feet down and away.
Ben - I'm located just outside of Wilson, North Carolina (USA). We're about 45 miles East of Raleigh - just off of Interstate 95.
Bach On
I just downloaded REW. I'll see what - if anything - I can do. What exactly should I try to post?
Mark - the mike was a foot away from the nearest HC12 and inches away from the rear of the bass box. I'm listening through the access doorway from about 9 feet down and away.
Ben - I'm located just outside of Wilson, North Carolina (USA). We're about 45 miles East of Raleigh - just off of Interstate 95.
Bach On
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Hi Bach On,
Good to hear that you were able to listen to the Big Box w/ two HC12s, and that the result is promising. The second subwoofer together with the change to the SI HT18s should give you the volume you need.
I fleshed out your geometry from Post #556 to get a feel for the available volume; see attached (What looks like a drawing is really just a sketch w/ notes. You'll have to figure out how to build this thing, and how to get it into the loft. You may have to build that in place, and provide for a removable driver baffle. Don't forget some protective grill, or so, for the driver(s).)
I also ran some more simulations.
Regards,
P.S.: Your pace is just fine.
Thanks again for the terrific work. I took a look at the "drawing". Hmmm. The clearance at the back of that driver is really close with that 18 inch driver and the hypotenuse wall.
I do think the ported bass box with the two 15 inch drivers is putting out pretty good sound. I do notice some "thruming" in the box. A short note seems to have reverb. That bothers me. But the box does seem tight with little that I would describe as rattles or wood flexing. I do suspect I need to add a wood brace between the front and rear walls. I originally had one in there, but removed it to add the port.
I believe I also need to substantially increase the damping fill in the box. I saw where someone sprayed adhesive to the interior walls and applied poly-fill to the still-sticky walls to reduce reflections. I've only got two or three inches of fiberglass damping material at the bottom of the box. I think more might help.
I plan to use both the 15 inch box AND add the 18 inch corner cabinet. When you've got a volume control you can always cut back on the volume. It doesn't work as well the other way.
Thanks for the encouragement. I'm trying to do a lot of things at once and it seems that I sometimes feel stretched too thin.
I'm also angry at myself for getting the speakers in the chamber without planning better. I should have put that bass box in first. Now I'm having to work in a very cramped space. I can't reorganize things until we get those big pipes removed. The alternative is to haul all the speakers out and start over. And the men in the church who helped put them in will think I'm stupid for doing it wrong the first time.
Finally, DrDyna mentioned the sound level in the nursery. The wall is 2x4s with one layer of sheetrock. I'm thinking we need to add some fiberglass insulation and a sheet of foam insulation or a sheet of sheetrock on the interior wall of the chamber. It won't begin to soundproof the room, but it might reduce the level of sound that carries into the nursery. We'll probably need to do something similar with the door.
And to top it off, our Organ Tech has hit us with a much steeper charge than anticipated. I've got to go to the church council and ask for $3,000 more. I don't know if they'll go for it.
Like the man said, "Murphy was an optimist."
Bach On
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My apologies - I've been reading the forum on my phone recently so had neglected to download the attachment mentioned to get the full details!
Thanks for weighing in, Art
I was going from what I'd read on AVS re: the original 'Marty' design, where I'm sure someone was saying tuning was lowered by a few Hz when the port was along the floor... I am happy to be corrected as I am still very noob!FWIW, my SI-based setup carries bass through my solid concrete block walls - my neighbour said it carries along the front wall of the building, where her living room wall joins my wall (we have slightly staggered apartments), so I fear you will struggle to attenuate the lower frequencies to any great degree unless you add a load of mass into the wall!
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