I'm sure there are better methods than the dbx auto eq for getting things eq'd correctly, but I find that it at least helps speed things up. I choose the "best" method which involves moving the mic to four different positions across the room and having the dbx give me it's best eq based on those positions. Then I use the parametric on my mixer to fine tune it to my liking. It sounds very close to my studio, which uses Soundworks Reference 4 to eq the room. Is it perfect? no way. But it does a couple things for me: 1) gives me a similar eq curve to my studio that my ear is already accustomed to. 2) roots out problem frequencies that plague certain rooms. I can't tell you how many times I've been complimented on how great my system sounds in rooms that are known to be difficult to mix in.
On the beta 52 mic thing, it turns out that after watching several videos I've learned what you already stated...the mics sounds way different depending on placement. In my case it was my first time using it and the port hole was so low that I couldn't put the mic very far inside the port because of my mic stand. Another soundman told me that that was the problem. lesson learned.
On phase alignment, I don't know much besides when it's out of phase it cancels and sounds like crap. lol. In my simple thinking I thought that it was an easy thing to say what delay time do I need for a front loaded top sitting on top of a keystone. I have read that it's somewhere between 5-9ms. one guy said 7ms is what sounds best to him. I've even tried it with no delay and it still sounded good (probably not at the crossover frequency though.) I'm just a little OCD and want it to sound it's absolute best. I'm gonna have to contract a local sound guy with Smaart to come over and take a look.
I'm starting on two more cabinets today...I'm excited!
On the beta 52 mic thing, it turns out that after watching several videos I've learned what you already stated...the mics sounds way different depending on placement. In my case it was my first time using it and the port hole was so low that I couldn't put the mic very far inside the port because of my mic stand. Another soundman told me that that was the problem. lesson learned.
On phase alignment, I don't know much besides when it's out of phase it cancels and sounds like crap. lol. In my simple thinking I thought that it was an easy thing to say what delay time do I need for a front loaded top sitting on top of a keystone. I have read that it's somewhere between 5-9ms. one guy said 7ms is what sounds best to him. I've even tried it with no delay and it still sounded good (probably not at the crossover frequency though.) I'm just a little OCD and want it to sound it's absolute best. I'm gonna have to contract a local sound guy with Smaart to come over and take a look.
I'm starting on two more cabinets today...I'm excited!
wouldn't the delay time be governed by physical placement of the top with respect to the sub?
until Harrison produced a crossover that allowed a delay time between bands with old school Martin Mids and the 115 bass bins it was standard practice to overhang the back of the mids 2.25 inches beyond the back of the bass bins in order to acheive a proper phase sum across a 12 db per octave Butterworth filter...
i don't know what the acoustic center of Keystone sub is and depending on just what you have for a Mid/Top it's hard to say what delay would produce a beneficial alignment....
until Harrison produced a crossover that allowed a delay time between bands with old school Martin Mids and the 115 bass bins it was standard practice to overhang the back of the mids 2.25 inches beyond the back of the bass bins in order to acheive a proper phase sum across a 12 db per octave Butterworth filter...
i don't know what the acoustic center of Keystone sub is and depending on just what you have for a Mid/Top it's hard to say what delay would produce a beneficial alignment....
Yes, as well as the distance between the two and the measurement/listening location.
Exactly.
https://forums.prosoundweb.com/index.php?topic=133846.0
As Ivan Beaver, who has measured delay and phase of hundreds (11 years later, probably thousands) of tapped and front loaded horns wrote:
"As a general rule-the "delay" time for a tapped horn is somewhere between the physical length of the horn and the loudspeaker driver exit to the horn. How much depends on what frequency you are talking about".
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Thank you Art.
Yes I meant Table Bench (Google Translate is not always perfect ;-) )
I have 2 more questions:
1) What are the Q pieces for? (not sure what cleat is and Google Translate doesn't help much with this one). My guess is they are holding the front panel E. If so, do they need to be 43.5 inches long ? I have looked at some assembly pictures, but only one shows something like Q pieces.
2) About the 'holding' wood parts, like I, J, K, L, O, Q, I'm thinking using left over of Russian Birch 5/8" I have, and save as much as I can of the 3/4" I bought for this project. My guess is it's ok to use 5/8" for parts I, J, K, L, O, Q, but just in case, I'm asking if it's ok.
If you have a link on the assembly procedures or pictures on Github or Reddit, it would be very useful.
Thank you very much!
A "cleat" is a strip fastened across something to give strength or hold in position. The Q, P, and R cleats are the frame that part E, the Keystone exit panel is attached to. "Q" runs the length of the interior height, 43.5 inches, P and R are horizontal.
Russian Birch 5/8" should be OK for the bracing if you are accurate in screw placement.
Assembly Procedure goes something like this:
Cut 1/8” tempered hardboard for front and back templates
Cut top and bottom templates
Cut speaker baffle/back templates
Loft cabinet according to plans on tempered hardboard templates with screw & t-nut positions
Use the loft plans to make templates from tempered hardboard for trapezoidal shapes of “G”, “I”, “J”, “K”, & “N” parts
Cut parts “I”, “J”, “K”, “N” according to templates
Cut parts “O” through “U”
Cut main parts A through H (excepting G), label each in the center with the letter normal to the vertical position. Part F requires the lower end cut to 89 degrees, label the forward side to avoid reversal.
_____________________
3/4” Round Sides “A” front & back, mark screw positions front, back & horn
3/4” Round Top & Bottom part C all four sides
_____________________
Round lower portion of part M between “L” braces
Round Front and Back Brace “L” portions in horn path
Mark foot, horn and brace positions and screw pattern on Bottom part “C”
_____________________
Mark Back part “B” horn brace & drill “J” & “K” positions,
Drill Connector holes in Back part “B”
____________________
Mark Speaker Baffle “F” speaker center, T-nut holes
Mark Speaker Baffle “F” Wing Brace “N” & Center Horn Brace “I” positions
Mark Horn Back “H” drill holes and Horn Brace “I, “J’, “K” positions on
Mark drill holes and horn positions on Sides “A” Left & Right, note mirror image
Drill Baffle “F” t-nut holes
Cut speaker hole with jasper jig on router
Install speaker T-nuts with glue, sand speaker cut out rough edges smooth
_____________________
Mark “E” Keystone Exit 3/8” inside of four corners
Drill 3/4” holes in Keystone exit corners
Draw connecting lines between the corner holes
Jig saw Keystone Exit hole
1/4” round Keystone Exit hole interior & exterior, sand off exterior hard edge
_____________________
Mark & drill T-nut holes in part “O”, round 3 sides, install T-nuts
Assemble Wing Brace part “N” to “O”
_____________________
Install Wing Braces assembly “N & O” to Speaker Baffle “F”
Install Horn Top “G” to Horn Back “H”
Install Mid Back Horn Brace “K” to Horn Back “H
Attach Horn Braces “K” & “J” & to Horn Back “H”
Attach Center Horn Brace “I” to and Horn Top “G” to Speaker Baffle “F”
Install Front Bottom Cleat “R” to bottom Panel “D”
Install Exit Cleat “P” to Top Front Panel “D”
Assemble Left Side “A” to Back “B”
Assemble Top Front Panel “D” to Left Side “A”
Assemble top and bottom “C” to left side “A” and Back “B”
Install Horn Baffle assembly “FGH” to Left Side “A”
Secure speaker wire leaving service loop by connector holes
Install right Side “A”
Install Front Side Cleats “Q”
Drill Keystone Exit Panel “E pilot holes into cleats
Drill and countersink Exit Panel “E” pilot holes to screw size
Mark 1/4” Wing Brace holes Keystone Exit Panel “E” from inside
_____________________
Fill screw holes and sand
Primer Paint interior & exterior
Finish Texture paint exterior
Install speaker, check polarity,
Staple grill cloth to Keystone Exit Panel “E” interior
Install Panel “E”
_____________________
These guys assemble a Keystone in 30 seconds
:
Good luck!
Art
Russian Birch 5/8" should be OK for the bracing if you are accurate in screw placement.
Assembly Procedure goes something like this:
Cut 1/8” tempered hardboard for front and back templates
Cut top and bottom templates
Cut speaker baffle/back templates
Loft cabinet according to plans on tempered hardboard templates with screw & t-nut positions
Use the loft plans to make templates from tempered hardboard for trapezoidal shapes of “G”, “I”, “J”, “K”, & “N” parts
Cut parts “I”, “J”, “K”, “N” according to templates
Cut parts “O” through “U”
Cut main parts A through H (excepting G), label each in the center with the letter normal to the vertical position. Part F requires the lower end cut to 89 degrees, label the forward side to avoid reversal.
_____________________
3/4” Round Sides “A” front & back, mark screw positions front, back & horn
3/4” Round Top & Bottom part C all four sides
_____________________
Round lower portion of part M between “L” braces
Round Front and Back Brace “L” portions in horn path
Mark foot, horn and brace positions and screw pattern on Bottom part “C”
_____________________
Mark Back part “B” horn brace & drill “J” & “K” positions,
Drill Connector holes in Back part “B”
____________________
Mark Speaker Baffle “F” speaker center, T-nut holes
Mark Speaker Baffle “F” Wing Brace “N” & Center Horn Brace “I” positions
Mark Horn Back “H” drill holes and Horn Brace “I, “J’, “K” positions on
Mark drill holes and horn positions on Sides “A” Left & Right, note mirror image
Drill Baffle “F” t-nut holes
Cut speaker hole with jasper jig on router
Install speaker T-nuts with glue, sand speaker cut out rough edges smooth
_____________________
Mark “E” Keystone Exit 3/8” inside of four corners
Drill 3/4” holes in Keystone exit corners
Draw connecting lines between the corner holes
Jig saw Keystone Exit hole
1/4” round Keystone Exit hole interior & exterior, sand off exterior hard edge
_____________________
Mark & drill T-nut holes in part “O”, round 3 sides, install T-nuts
Assemble Wing Brace part “N” to “O”
_____________________
Install Wing Braces assembly “N & O” to Speaker Baffle “F”
Install Horn Top “G” to Horn Back “H”
Install Mid Back Horn Brace “K” to Horn Back “H
Attach Horn Braces “K” & “J” & to Horn Back “H”
Attach Center Horn Brace “I” to and Horn Top “G” to Speaker Baffle “F”
Install Front Bottom Cleat “R” to bottom Panel “D”
Install Exit Cleat “P” to Top Front Panel “D”
Assemble Left Side “A” to Back “B”
Assemble Top Front Panel “D” to Left Side “A”
Assemble top and bottom “C” to left side “A” and Back “B”
Install Horn Baffle assembly “FGH” to Left Side “A”
Secure speaker wire leaving service loop by connector holes
Install right Side “A”
Install Front Side Cleats “Q”
Drill Keystone Exit Panel “E pilot holes into cleats
Drill and countersink Exit Panel “E” pilot holes to screw size
Mark 1/4” Wing Brace holes Keystone Exit Panel “E” from inside
_____________________
Fill screw holes and sand
Primer Paint interior & exterior
Finish Texture paint exterior
Install speaker, check polarity,
Staple grill cloth to Keystone Exit Panel “E” interior
Install Panel “E”
_____________________
These guys assemble a Keystone in 30 seconds
:Good luck!
Art
Here is my recent build video. as amateur as it gets. I wish I would have read the instructions Art posted recently, but I was in the middle of the build when he posted the instructions and I didn't see them. So I limped thru the install as best as I could. All mistakes are in the video, along with corrections. The speakers ended up sounding great.
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Just wanted to say a massive thank you for all the time and effort put into designing and testing the keystones and syntripps. Finished mine recently and took them out for their first outing not too long ago taking over from a live band at a local resteraunt/venue. Needless to say when we turned it all on pretty much everything in the kitchen ended up on the floor and the crowd absolute loved it!!
Many thanks!!
Many thanks!!
Just getting done building two KS to replace a handful of BFM T39s. Using the Lab12 drivers for the time being. Tested one cab and heard some distortion.
Notched it out with EQ, and that was around 110 to 120 Hz.
Is there any benefit or detriment to cutting the lab12 baffle openings all the way through when using the adapter plate for them? Or does the partial occlusion of the opening act kinda like a slot loaded baffle?
Notched it out with EQ, and that was around 110 to 120 Hz.
Is there any benefit or detriment to cutting the lab12 baffle openings all the way through when using the adapter plate for them? Or does the partial occlusion of the opening act kinda like a slot loaded baffle?
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No benefit, only detriment as cutting holes for 12" drivers in the baffle would require a major cabinet re-build to convert to 18" use. If one had no intention to use 18", direct cutouts for the 12" drivers would eliminate the need for the adapter plate.
Not a slot load, as the cross sectional area of the 18" cutout is nearly the same as 2x12", but the adapter plate does increase the VTC (Volume of Throat Chamber) a bit.
With a pair of LAB 12", the output peaks around +6dB in the 90-100Hz range, though distortion is only in the <2% range.
The SPL in the peak range may be rattling something, check for buzzes and leaks with a sine wave sweep.
Art
Excellent! Found a leak at the driver gasket. Got some 1/2" neoprene weatherstripping and removed/replaced the old gasket. Just cinched it back up. Pretty sure that was the problem. But I'll get some tests in sometime later this week.
Thanks!
Quick update for the zero of you that lost sleep over my distortion findings:
I'm an idiot. I found 3 things besides the driver gasket that could've been causing issues. I fixed the driver gasket and finally got a chance to run a few tones through. I initially thought I fixed it because the tones feel louder than program music, which is how I heard the distortion in the first place.
Tone generator at what I thought was plenty loud sounded clean. So I hooked up a main and started rough tuning my DriveRack settings to a rock playlist. the first kick at higher volumes brought the "distortion" back.
So I disassembled.
I reconed 2 drivers. I did a terrible job of keeping the braided leads off the cones. So I fixed that.
Found a delamination on the back side of the baffle where I used a dull bit to drill for the driver mounting screws and tee nuts. It was a piece about an inch wide and 1.5 inches long. It was still attached at one end. Got out the CA glue and secured that.
Also found a rub mark on the surround where I was sloppy with mounting the driver on the baffle. The cutout edge was barely touching the surround.
Finally, during initial assembly, I used a chisel to remove the squeeze-out of PL glue in the area of the mouth where you can see through the keystone port. There was an 8" long bead that was sticky enough to attach in the throat opening, but looked like it was flapping around on one end. Not entirely sure how that ended up there, but I assume I blew it in there at some point with compressed air.
So, 2 things flapping in the wind and a sloppy job of mounting the drivers, and a sloppy recone. Not sure what exactly was responsible for the noise I heard, but it is gone, now.
Cab 2 sounded lovely on the 1st run. Now they both sound great. Night and Day difference in the tone between 4 BFM T39s and 2 of these, with very comparable spl levels... while reusing the same drivers from the BFM cabs. The only place I felt that output wasn't better is around 80Hz. There's a little dip there. 4dB of boost at 80 brought it back to what I think is even (or a little bit better, really). The lower extension sounds fantastic. I had to HP the BFM boxes at 40 in a single pile (or 45 if split stack). And even though the BFM boxes were cleaner and a comparable to the output of my older EV 18" subs, they still sounded like they were built with 1/2" ply. They never sounded solid. These boxes actually sound cleaner
I'm an idiot. I found 3 things besides the driver gasket that could've been causing issues. I fixed the driver gasket and finally got a chance to run a few tones through. I initially thought I fixed it because the tones feel louder than program music, which is how I heard the distortion in the first place.
Tone generator at what I thought was plenty loud sounded clean. So I hooked up a main and started rough tuning my DriveRack settings to a rock playlist. the first kick at higher volumes brought the "distortion" back.
So I disassembled.
I reconed 2 drivers. I did a terrible job of keeping the braided leads off the cones. So I fixed that.
Found a delamination on the back side of the baffle where I used a dull bit to drill for the driver mounting screws and tee nuts. It was a piece about an inch wide and 1.5 inches long. It was still attached at one end. Got out the CA glue and secured that.
Also found a rub mark on the surround where I was sloppy with mounting the driver on the baffle. The cutout edge was barely touching the surround.
Finally, during initial assembly, I used a chisel to remove the squeeze-out of PL glue in the area of the mouth where you can see through the keystone port. There was an 8" long bead that was sticky enough to attach in the throat opening, but looked like it was flapping around on one end. Not entirely sure how that ended up there, but I assume I blew it in there at some point with compressed air.
So, 2 things flapping in the wind and a sloppy job of mounting the drivers, and a sloppy recone. Not sure what exactly was responsible for the noise I heard, but it is gone, now.
Cab 2 sounded lovely on the 1st run. Now they both sound great. Night and Day difference in the tone between 4 BFM T39s and 2 of these, with very comparable spl levels... while reusing the same drivers from the BFM cabs. The only place I felt that output wasn't better is around 80Hz. There's a little dip there. 4dB of boost at 80 brought it back to what I think is even (or a little bit better, really). The lower extension sounds fantastic. I had to HP the BFM boxes at 40 in a single pile (or 45 if split stack). And even though the BFM boxes were cleaner and a comparable to the output of my older EV 18" subs, they still sounded like they were built with 1/2" ply. They never sounded solid. These boxes actually sound cleaner
Right, it takes considerable mass loading to get an inert cab, roughly 2x its weight; an experiment:
https://db.audioasylum.com/mhtml/m....wmessage=&sort=score&sortOrder=DESC&forum=hug
https://www.audioasylum.com/cgi/t.mpl?f=hug&m=175268
https://db.audioasylum.com/mhtml/m....wmessage=&sort=score&sortOrder=DESC&forum=hug
https://www.audioasylum.com/cgi/t.mpl?f=hug&m=175268
That was terribly worded. I didn't mean that the BFM boxes were cleaner than the Keystones. I meant to compare the BFM to my old EV subs. The T39s were my first foray into horn loaded subs. The direct radiator EVs I had were gnarly and full of lovely spots of distortion. They sounded like punk rock, though. The T39s were much cleaner sounding. But they always sounded... I don't know. Just had some undesirable overtones, I guess. Especially up close.
@weltersys when you design a bass driver into a horn like the Keystone, there's a certain size that the very first part of the mouth is small. What determines the size of the beginning of the horn? If I'm looking at it saying that it fires into the horn and goes to the right and then wraps around left and then pass by the driver. The part I'm talking about would be directly left of the driver. The "start" of the horn. What determines that starting size? Is it relative to 1/8" of the lowest wavelength desired? Is there a reason that it's a few inches of flat space and not a small point at the beginning?
The cross-sectional area in the throat of the horn compared to the driver's Sd determines it's compression ratio. Higher compression ratios tend to be more efficient, but put more stress on the cone.
No. The path length of the horn is (approximately) 1/4 wavelength of Fc (horn cutoff) or Fb (box tuning frequency).
A higher compression ratio on one side of the cone may cause it to rock or wobble when driven at high power which can cause distortion or even voice coil dragging.
Art
OK, one last question:
I have 2 Peavey IPR2 3000 amps for sub duty. I plan to build 4 more Keystone subs and load with an 18.
Which driver makes the most sense with those amps?
I just got done with my 2nd show using the dual lab12 loaded boxes (outside show in a downtown area with reasonable sound ordinance limitations). I'll probably keep that pair as-is for smaller shows or a 2nd rig. They sound so much better than my old subs. Thanks for such a great design!
I have 2 Peavey IPR2 3000 amps for sub duty. I plan to build 4 more Keystone subs and load with an 18.
Which driver makes the most sense with those amps?
I just got done with my 2nd show using the dual lab12 loaded boxes (outside show in a downtown area with reasonable sound ordinance limitations). I'll probably keep that pair as-is for smaller shows or a 2nd rig. They sound so much better than my old subs. Thanks for such a great design!
The IPR2 3000 is rated at 1750 watts at 2 ohm, 950 at 4 ohms, 525 at 8 ohms.
Assuming one cabinet per amp channel, the BC18SW115-4 or the BC18TBW100-4 will have about the same output, though the BC18SW115-4 would have less power compression if running low crest factor music.
The IPR2 3000 does not have enough power to use the peak potential of either driver, though is more than enough for the lower impedance LAB12 pair.