As Art brought quite interesting discussion about benefits and drawbacks of line arrays /column speakers with small full range drivers, I would like to present couple of REW measurements, together with my observations:
a) Measurement #1: Loss of line array output on various distances (without DSP) => 1m, 2m and 4m
c) Measurement #2: Integration of THAM 12 and line array - amplifier gain adjustment (with DSP applied)
Measurement #1 comments:
- This was taken with one line array, and with "Hypex" FA502 completely flat => no DSP applied, no corrections of any kind, no crossovers.
Idea behind this measurement is to check if 3dB loss of output per doubling distance happens only on very narrow frequency range or on wider frequency range.
So my idea is to first go with 1m distance, but with -12dB output on REW.
Then, I would double the distance to 2m , but increase output only 3dB (to -9dB).
After that, I would again double the distance of the mic to 4m, but will increase output only 3dB (to -6dB).
Finally, I would increase distance to 8m, and will increase output to -3dB.
If the line array theory of "3dB output drop per doubling distance" is correct, all four measurements should align very well.
Above measurements shows two things:
a) That from 200Hz to 16kHz there is no significant variation between measurements,
b) That even without any correction applied 3Fe25 are very linear drivers
Measurement #2 comments:
This measurement was done with one THAM 12 and with one line array.
Line array was mounted on 60cm pole (threaded to THAM 12 top).
"Hypex" FA502 had DSP applied on both channels (both PEQ, and cross-overs).
In order to get desired loudness curve, I've reduced gain on line array amp channel to -8dB (this is overall gain), but kept THAM 12 amp gain to 0dB.
As you can see above, with PEQ applied, some frequencies on line array are down as much as - 13dB when compared to THAM 12 (in example, 200Hz),
but actual sound output from line array is relatively flat & consistent from 200Hz all the way to 15kHz.
What is interesting, even with such gain setting arrangement, line arrays can keep without any issues with THAMs ,especially on 10m distance range, where line arrays output drops less than THAMs.
I believe that in most of cases, PA systems are typically tuned with some kind of loudness curve - how much low end should be "hotter", is mostly matter of preferences & type of program material (I am not taking into account actual venue location/ambient conditions, etc.).
My experience with this small system so far , that by keeping line array amplifier gain -6dB to -12dB lower than THAM 12, produces pleasant sound with most of the music genres.
a) Measurement #1: Loss of line array output on various distances (without DSP) => 1m, 2m and 4m
c) Measurement #2: Integration of THAM 12 and line array - amplifier gain adjustment (with DSP applied)
Measurement #1 comments:
- This was taken with one line array, and with "Hypex" FA502 completely flat => no DSP applied, no corrections of any kind, no crossovers.
Idea behind this measurement is to check if 3dB loss of output per doubling distance happens only on very narrow frequency range or on wider frequency range.
So my idea is to first go with 1m distance, but with -12dB output on REW.
Then, I would double the distance to 2m , but increase output only 3dB (to -9dB).
After that, I would again double the distance of the mic to 4m, but will increase output only 3dB (to -6dB).
Finally, I would increase distance to 8m, and will increase output to -3dB.
If the line array theory of "3dB output drop per doubling distance" is correct, all four measurements should align very well.
Above measurements shows two things:
a) That from 200Hz to 16kHz there is no significant variation between measurements,
b) That even without any correction applied 3Fe25 are very linear drivers
Measurement #2 comments:
This measurement was done with one THAM 12 and with one line array.
Line array was mounted on 60cm pole (threaded to THAM 12 top).
"Hypex" FA502 had DSP applied on both channels (both PEQ, and cross-overs).
In order to get desired loudness curve, I've reduced gain on line array amp channel to -8dB (this is overall gain), but kept THAM 12 amp gain to 0dB.
As you can see above, with PEQ applied, some frequencies on line array are down as much as - 13dB when compared to THAM 12 (in example, 200Hz),
but actual sound output from line array is relatively flat & consistent from 200Hz all the way to 15kHz.
What is interesting, even with such gain setting arrangement, line arrays can keep without any issues with THAMs ,especially on 10m distance range, where line arrays output drops less than THAMs.
I believe that in most of cases, PA systems are typically tuned with some kind of loudness curve - how much low end should be "hotter", is mostly matter of preferences & type of program material (I am not taking into account actual venue location/ambient conditions, etc.).
My experience with this small system so far , that by keeping line array amplifier gain -6dB to -12dB lower than THAM 12, produces pleasant sound with most of the music genres.
Attachments
Here's an article I wrote on this subject: https://www.prosoundweb.com/spec-wars-looking-inside-loudspeaker-spl-specifications/
Chris
Bubba,
Thanks for sharing the measurements!
The 120dB range makes it difficult to see the variations, some of which may be due to wind/environment noise and ground reflection cancellations from path length differences between direct and the 159cm mic height.
A) The octave between 1-2kHz is within 3dB, there are variations of 3-6dB above and below that octave, more below 200Hz.
Those differences are the equivalent of doubling distance, which seems to be a significant variation.
B) +/-7dB, not too bad, would be interesting to see the off axis variation.
Seems the Tham conforms to the -3dB per doubling of distance better than the line array
The line's -10dB "scoop" from around 160-320Hz at 8 meters seems more like what I'd expect.
Placing the line horizontal on the ground, preferably smooth cement or asphalt rather than grass (grass absorbs high frequencies) with the mic also on the ground plane would give more consistent results.
Cheers,
Art
Hi Chris,
What is interesting, I've accidentally found your article when I was searching something on Prosoundweb forum - quite interesting insight into marketing tricks in PA industry, this would explain many things
I would say that many PA manufacturers are already to far away from reality, I mean, if you check almost any 2-way PA active bass reflex box, many of them claim SPL above 130dB/1m ....and I am now aware what you need to do to have steady-state, real 120dB measurements with REW.No problems, similarly as you, I like both assembling of the boxes, but i also like measurements & testing as well
159cm height I purposely used as it is roughly head (ear) position of average standing person, and center line of line arrays.
Ground cancellation are unfortunately unavoidable, but that is not the problem from me, I want to see actual,"real-life" scenario, as most of the events will be held in open spaces with hard ground, and with lot of reflective surfaces anyway,
Indoors, I used system only couple of times, but it was way overkill for this type of events=>on one event, we were inwooden cottage, with open space of about 30-40m2.
THAMs were shaking wooden construction, so when you were on toilet, the whole toilet was shaking together with you
Line arrays indoors, due large horizontal coverage, have lot of reflections, which indeed cause cancellations but also large increase in some midrange frequencies, so indoors, I typically, reduce line array gain on amp even more (-12 or -15dB, compared to THAMs).
Hm I would agree and disagree - if you check all graphs you can see that on longer distance measurements , some frequencies have higher output than on lower distances.
Correct me if I am wrong, but if you have measurement with four different distances , and if the output drop linearly 6dB per doubling of the distance, then each contour of the four curves would be offset for this 6dB, and with my +3dB compensation of the gain , there would be still offset between each measurement - contours shouldn't cross couple of times.
I have off axis measurements, but I need to find them.
This is puzzling me as well, as the line arrays contours are pretty much with my previous measurements with doubling the distance, but THAMs, are not inline with my expectations => to sort this mystery, I am planning new set of measurements with more points, so we'll see if there was my mistake or THAMs throw magically further without any lossSeems the Tham conforms to the -3dB per doubling of distance better than the line array
Hm , I could try that as well, good advice!
As promised to Art. here are three measurements of THAM and line arrays, all three measured on 8 meter radius, but with mic placed on various angles:
a) Orange line: on axis,
b) Blue line: 30° off-axis,
c) Brown line: 45° off-axis:
I've zoomed SPL range Y-axis when compared to previous measurements, in order to emphasize amplitude differences:
- The 30° measurement drops after 6kHz around 1dB, and 45° measurement drops more sharply on same 6kHz - drop is up to 7-8 dB.
Up to 6kHz all three lines are very close , so low-mid, mid and upper mid area is covered without any noticeable drop in level.
a) Orange line: on axis,
b) Blue line: 30° off-axis,
c) Brown line: 45° off-axis:
I've zoomed SPL range Y-axis when compared to previous measurements, in order to emphasize amplitude differences:
- The 30° measurement drops after 6kHz around 1dB, and 45° measurement drops more sharply on same 6kHz - drop is up to 7-8 dB.
Up to 6kHz all three lines are very close , so low-mid, mid and upper mid area is covered without any noticeable drop in level.
So, after spending one year with my system with THAM 12 , full-range line arrays (column speakers) and "Hypex" FA502 plate amps, here are my impressions (I'll try to be objective as much as possible):
1. Overall sound quality:
a) Pros:
b) Cons:
- Realistically, I never expected to get chest pounding bass from 3.5" line array drivers down to 100Hz, and they can't produce that for sure.
Currently , I'm crossing them around 160Hz, which is around maximum upper frequency for THAMs.
I wish that THAMs could be crossed just little bit higher , maybe 180, 200Hz, as this could relieve small 3Fe25 membranes from the excessive movement.
2. Efficiency:
a) Pros:
- I was running "Hypex" FA 502 like this:
a) Channel A: up to 350W RMS for THAM 12 (as Oberton 12B450 is 8 Ohm driver), 0dB gain on DSP,
b) Channel B: up to 400 W RMS for line array (as 12 drivers have combined impedance of 6 Ohms), with 3 different gain settings on DSP (-6, -9, -12dB).
- With above power levels, line array has definitely sufficient efficiency to be combined with THAMs => I tried increasing gain on line array amps to -3dB (roughly 200W RMS per column speaker), but on some program material there could be to much mid/high for my taste,
b) Cons:
- I used 8 Ohm driver for THAMs, but could use 4 Ohm version to get little bit extra power with FA502 (500W RMS on 4 ohm).
3. Sound dispersion/area coverage:
a) Pros:
b) Cons:
- For my purposes, I don't require much better vertical coverage, so nothing special to complain.
4. Transportation:
a) Pros:
-Column speakers can be held in one hand, though THAMs require two hands, but nothing extreme.
- They should fit in almost any car.
b) Cons:
- Could maybe add additional handles on THAMs, as it is hard to grab them.
- Eventually, I could use driver with neodymium magnet to lighten THAMs few kg's.
1. Overall sound quality:
a) Pros:
- System sounds "larger" then it looks =>when I saw fragile "Faital Pro" drivers, I was worried that they will sound awful when pushed loud, but 24 drivers produce clean sound even on higher volumes.
- Midrange from the line array is excellent, and with DSP you can remove almost any harsh sound, even though they don't require so much EQ as I originally thought.
- High frequency tones produced by line array were also surprise, and better than I expected for 3.5" cone driver.
b) Cons:
- Realistically, I never expected to get chest pounding bass from 3.5" line array drivers down to 100Hz, and they can't produce that for sure.
Currently , I'm crossing them around 160Hz, which is around maximum upper frequency for THAMs.
I wish that THAMs could be crossed just little bit higher , maybe 180, 200Hz, as this could relieve small 3Fe25 membranes from the excessive movement.
- As Art noticed, you can't cheat physics, and there is small dip in line array mid-bass output in cross-over range...of course , this can be sorted out by adding additional box, with separate bass driver, but this will increase complexity.
- THAMs have usable output to 50Hz (actually 48Hz with little help from DSP and many REW measurements), and they provide great output to that frequency.
2. Efficiency:
a) Pros:
- I was running "Hypex" FA 502 like this:
a) Channel A: up to 350W RMS for THAM 12 (as Oberton 12B450 is 8 Ohm driver), 0dB gain on DSP,
b) Channel B: up to 400 W RMS for line array (as 12 drivers have combined impedance of 6 Ohms), with 3 different gain settings on DSP (-6, -9, -12dB).
- With above power levels, line array has definitely sufficient efficiency to be combined with THAMs => I tried increasing gain on line array amps to -3dB (roughly 200W RMS per column speaker), but on some program material there could be to much mid/high for my taste,
b) Cons:
- I used 8 Ohm driver for THAMs, but could use 4 Ohm version to get little bit extra power with FA502 (500W RMS on 4 ohm).
3. Sound dispersion/area coverage:
a) Pros:
- Line arrays have relatively wide dispersion horizontally, and in practice you can interesting effects - for example, during first testing, I was listening them for hours, but from various locations inside approx. 50 meter radius,
- They spread sound widely, and due reflections you get even better coverage that I expected - when you don't see speakers, it is hard to precisely pin point exact location of the sound, it is hard to describe, but the sound is simply "everywhere".
- Vertical dispersion is limited, though this is in my case sorted by raising column speakers to required height (center line of line arrays is around head position of standing listener).
- They have 3dB drop with distance , so they actually throw further =>not on all frequencies, but quite large portion of the range, and this can be heard in my video clips,
b) Cons:
- For my purposes, I don't require much better vertical coverage, so nothing special to complain.
4. Transportation:
a) Pros:
-Column speakers can be held in one hand, though THAMs require two hands, but nothing extreme.
- They should fit in almost any car.
b) Cons:
- Could maybe add additional handles on THAMs, as it is hard to grab them.
- Eventually, I could use driver with neodymium magnet to lighten THAMs few kg's.
So, after one year of listening to the system, the one small drawback that I noticed was lack of lowest octave - as stated above, THAMs could go down to 48Hz, even in open space (after careful applying some DSP, and 36Hz 48db/octave HP), and that is perfectly fine for most songs, but when they are used with low, sub bass-heavy music, they lack authority, as their output is decreasing very steeply.
On the beginning of this year I was going through various topics on this forum , searching through possible ideas for suitable subwoofer that could be used in combination with my existing THAMs & line arrays.
I could go with 18" version of THAM, but just for my curiosity in the end, I've decided to go with 18" version of Keystone sub for couple of reasons:
a) It is extremely well documented project,
b) It goes sufficiently low for my purposes (low 30-ish Hz),
c) It is based on tapped horn design, which has same benefits (and drawbacks) of THAMs, but it has different folding and interesting mouth exit.
Around spring time, I was searching for suitable 18" driver & checking Hornresp simulations => while B&C 18SW115 is obviously the first candidate performance wise, the price seemed a little bit to steep, so I almost purchased cheaper alternative B&C TBW100...I said almost, as for some reason, I asked my self is there another replacement to TBW100.
And then I accidentally found interesting Beyma 18QLEX1600Fe sub driver:
https://www.beyma.com/speakers/Fich...ecnica-baja-media-frecuencia-18QLEX1600Fe.pdf
This driver could be purchased at that time for even slightly less price than B&C TBW100, so I ordered one unit.
Hornresp simulation shows that it should work in Keystone at least as good as B&C TBW100 -here is simulation with 1200W applied:
After ordering driver, I immediately started working on conversion of Keystone Sub plan measurements to metric, and simultaneously, I started to draw 3D model of the complete Keystone Sub.
In order to mount internal bracing, I've created screw holes for each brace & adjacent surface, so that during actual assembly I can quickly glue brace & tighten brace at exact position with wood screws.
On the beginning of this year I was going through various topics on this forum , searching through possible ideas for suitable subwoofer that could be used in combination with my existing THAMs & line arrays.
I could go with 18" version of THAM, but just for my curiosity in the end, I've decided to go with 18" version of Keystone sub for couple of reasons:
a) It is extremely well documented project,
b) It goes sufficiently low for my purposes (low 30-ish Hz),
c) It is based on tapped horn design, which has same benefits (and drawbacks) of THAMs, but it has different folding and interesting mouth exit.
Around spring time, I was searching for suitable 18" driver & checking Hornresp simulations => while B&C 18SW115 is obviously the first candidate performance wise, the price seemed a little bit to steep, so I almost purchased cheaper alternative B&C TBW100...I said almost, as for some reason, I asked my self is there another replacement to TBW100.
And then I accidentally found interesting Beyma 18QLEX1600Fe sub driver:
https://www.beyma.com/speakers/Fich...ecnica-baja-media-frecuencia-18QLEX1600Fe.pdf
This driver could be purchased at that time for even slightly less price than B&C TBW100, so I ordered one unit.
Hornresp simulation shows that it should work in Keystone at least as good as B&C TBW100 -here is simulation with 1200W applied:
After ordering driver, I immediately started working on conversion of Keystone Sub plan measurements to metric, and simultaneously, I started to draw 3D model of the complete Keystone Sub.
In order to mount internal bracing, I've created screw holes for each brace & adjacent surface, so that during actual assembly I can quickly glue brace & tighten brace at exact position with wood screws.
After 3D design was completed, and checked for eventual clashes, I've had to optimize nesting of the parts on plywood stock.
Optimum CNC cutting combination was placement of all parts to 5 separate 18mm plywood pieces, where each stock piece is 1250 x 1240mm.
Even though the most of the parts could be cut by CNC router, there are few internal parts that had to be done on circular saw & angle jig.
As I didn't had access to table saw with precise adjustment of the cutting angle, I've made large table saw from existing hand-held circular saw installed upside down (and left-over material), plus I added simple sleds for straight cross-cuts, and one additional simple angle jig:
This simple jig is designed for smaller angles, ideally under 30°, and this will be sufficient for my purpose,
When placement of all parts was defined, then I prepared CNC cutting file, and started cutting all 5 plywood pieces:
When all parts were cut, I've cleaned the edges. Then, I've installed M6 T-nuts, and cut the one prong that is protruding towards hole center on all T-nuts.
Then, I've checked fitment of "Beyma" driver on the baffle- just to check if the main opening is correctly sized, and surround can freely move without touching plywood edge:
Optimum CNC cutting combination was placement of all parts to 5 separate 18mm plywood pieces, where each stock piece is 1250 x 1240mm.
Even though the most of the parts could be cut by CNC router, there are few internal parts that had to be done on circular saw & angle jig.
As I didn't had access to table saw with precise adjustment of the cutting angle, I've made large table saw from existing hand-held circular saw installed upside down (and left-over material), plus I added simple sleds for straight cross-cuts, and one additional simple angle jig:
This simple jig is designed for smaller angles, ideally under 30°, and this will be sufficient for my purpose,
When placement of all parts was defined, then I prepared CNC cutting file, and started cutting all 5 plywood pieces:
When all parts were cut, I've cleaned the edges. Then, I've installed M6 T-nuts, and cut the one prong that is protruding towards hole center on all T-nuts.
Then, I've checked fitment of "Beyma" driver on the baffle- just to check if the main opening is correctly sized, and surround can freely move without touching plywood edge:
After that, I tried "dry" assembly => checking fitment of all parts, trying to identify issues before applying glue, and correcting issues if possible.
Additionally, I've marked screw holes for attaching internal braces:
(NOTE: Unfortunately, at that time I didn't catch one major fail => the driver baffle itself was cut with driver hole offset from the centerline => the offset was 50mm horizontally, and at that time I didn't catch it, but it would be so much easier that I replaced it simply with new piece at that stage.
Later investigation showed that CNC spindle was overdriven by too aggressive feed rate, X-axis stepper motor slipped and this slip created 50mm horizontal offset).
Additionally, I've marked screw holes for attaching internal braces:
(NOTE: Unfortunately, at that time I didn't catch one major fail => the driver baffle itself was cut with driver hole offset from the centerline => the offset was 50mm horizontally, and at that time I didn't catch it, but it would be so much easier that I replaced it simply with new piece at that stage.
Later investigation showed that CNC spindle was overdriven by too aggressive feed rate, X-axis stepper motor slipped and this slip created 50mm horizontal offset).
When "dry" fitment check was completed, all screw holes for braces were marked, I've disassembled all parts - some of the parts have to be slightly sanded with sand paper/file, but nothing too much.
After final dressing of the parts have been done, I've used compressed air to blow any remaining dust and went for final assembly:
After final dressing of the parts have been done, I've used compressed air to blow any remaining dust and went for final assembly:
Attachments
When the whole box was fully assembled, I've check fitment of the removable mouth plate - I was not satisfied with flatness of the four cleats, that will hold mouth plate, so I took a hand router and resurfaced everything until flat:
After that, I've used polyester kit to cover all screws & wooden dowels, and sanded everything with belt sander:
Then I've used loudspeaker paint and painted box and removable mouth separately:
After that, I've used polyester kit to cover all screws & wooden dowels, and sanded everything with belt sander:
Then I've used loudspeaker paint and painted box and removable mouth separately:
Now when the box was almost completely finished, I was looking at my CNC-cutting mistake (aka "the driver hole with 50mm offset") , and I decided to rectify this by making new adapter plate that will be positioned correctly, plus I would cut crescent-shaped plywood piece to cover empty area under new adapter:
When new driver mounting adapter was finally glued in position, the only thing that was left was creating gaskets for sealing removable mouth plate.
I've choose to use yoga mattress material, as it is relatively thick, but can be easily compressed and can be quickly cut to size.
So'I ve cut material to separate pieces and glue them with 2-sided sticky tape.
Holes for mounting bolts were done with 60W soldering iron, quite easy & quick method:
Sealing of the driver was done with thick, self adhesive weather strip tape, and I also cut the mounting holes with soldering iron:
When new driver mounting adapter was finally glued in position, the only thing that was left was creating gaskets for sealing removable mouth plate.
I've choose to use yoga mattress material, as it is relatively thick, but can be easily compressed and can be quickly cut to size.
So'I ve cut material to separate pieces and glue them with 2-sided sticky tape.
Holes for mounting bolts were done with 60W soldering iron, quite easy & quick method:
Sealing of the driver was done with thick, self adhesive weather strip tape, and I also cut the mounting holes with soldering iron:
Once after sub driver was installed in position, I've installed removable mouth plate (by using M6 countersunk allen bolts).
Then I've installed lifting handles on top and bottom side, and I've installed M20 threaded adapters on top side, so I can mount main speakers on top of Keystone Sub if desired.
I've used very shallow lifting handles, that require only 10mm installation depth, as I wanted to avoid large handles that are protruding into horn too much.
Double Speakon connector plate was mounted on rear side for connection to amp.
As Keystone Sub will be passive, I had to use suitable amp for initial testing & DSP configuration - unfortunately at that time I didn't had suitable 19" rack amp, so I purchased additional "Hypex" FA502 amp and configured it to work in bridge mode (1200W RMS on 8 ohm).
In order to temporarily mount FA502 in my rack, I've designed simple plate adapter and cut it on CNC (19" wide, with 6H approx.):
Then I've installed lifting handles on top and bottom side, and I've installed M20 threaded adapters on top side, so I can mount main speakers on top of Keystone Sub if desired.
I've used very shallow lifting handles, that require only 10mm installation depth, as I wanted to avoid large handles that are protruding into horn too much.
Double Speakon connector plate was mounted on rear side for connection to amp.
As Keystone Sub will be passive, I had to use suitable amp for initial testing & DSP configuration - unfortunately at that time I didn't had suitable 19" rack amp, so I purchased additional "Hypex" FA502 amp and configured it to work in bridge mode (1200W RMS on 8 ohm).
In order to temporarily mount FA502 in my rack, I've designed simple plate adapter and cut it on CNC (19" wide, with 6H approx.):
The integration of Keystone Sub with the rest of the system was relatively straightforward - there are various crossover combinations between Keystone and THAMs, but for a start I used on my bridged "Hypex" FA502 (that is powering Keystone Sub) these settings:
With above settings, I assumed that there should be wide overlap between THAM 12's and Keystone, but first REW measurements showed that my initial delay settings are not correct => when both THAMs & Keystone were combined , there was a big peak between 90-125Hz, and much lower output from 40-90Hz.
Hmmmm, then I inverted polarity on Keystone , and tried to measure again => this time integration was much better, with much smoother output from 40 to 120 Hz (Orange line=>NON-inverted Keystone, Green line => inverted Keystone output):
I've saved these settings and organized one small, private party where Keystone Sub will be used for the first time - the location was perfect for this, as this is small but isolated open air sports center, with two tennis courts, one football pitch and one sand volleyball court.
Anyway, I've rented area comprising two tennis courts for 1 day event for around 25 guests (with additional 15 kids cca), and started with equipment installation from early morning.
After everything was installed, and before any guests arrived, I had a time to perform couple of REW measurements, play various audio material and record couple of video clips, so here are the details of the field layout and speaker placement:
The good thing was that I've had couple of helpful friends that could help me to bring equipment to location - as it was hot, summer day, we had to install improvised shade above equipment:
Now, couple of videos =>here are four videos, taken from various distances:
a) Video 1 => taken from about 6m distance (and going little behind to 10-12m ):
b) Video 2 => taken from about 20m distance:
c) Video 3 => taken from about 30m distance:
d) Video 4 => taken from about 40m distance:
- HP: 30 Hz , 24dB per octave
- LP: 90 Hz, 24dB per octave,
- PEQ: 36Hz, +3dB boost,
With above settings, I assumed that there should be wide overlap between THAM 12's and Keystone, but first REW measurements showed that my initial delay settings are not correct => when both THAMs & Keystone were combined , there was a big peak between 90-125Hz, and much lower output from 40-90Hz.
Hmmmm, then I inverted polarity on Keystone , and tried to measure again => this time integration was much better, with much smoother output from 40 to 120 Hz (Orange line=>NON-inverted Keystone, Green line => inverted Keystone output):
I've saved these settings and organized one small, private party where Keystone Sub will be used for the first time - the location was perfect for this, as this is small but isolated open air sports center, with two tennis courts, one football pitch and one sand volleyball court.
Anyway, I've rented area comprising two tennis courts for 1 day event for around 25 guests (with additional 15 kids cca), and started with equipment installation from early morning.
After everything was installed, and before any guests arrived, I had a time to perform couple of REW measurements, play various audio material and record couple of video clips, so here are the details of the field layout and speaker placement:
The good thing was that I've had couple of helpful friends that could help me to bring equipment to location - as it was hot, summer day, we had to install improvised shade above equipment:
Now, couple of videos =>here are four videos, taken from various distances:
a) Video 1 => taken from about 6m distance (and going little behind to 10-12m ):
b) Video 2 => taken from about 20m distance:
c) Video 3 => taken from about 30m distance:
d) Video 4 => taken from about 40m distance:
THANK YOU for demonstrating what a double bass drum kit sounds like with a tapped horn. I've heard countless distortions an bloated bass recordings, nothing showcasing midbass slam and punch. Progressive metal type tracks are what I use to test sound systems. That band playing with double bass going is difficult to achieve in a good sound system with double bass. These are my two tracks that few systems reproduce effectively:
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Dr Suad:
No problem, I am glad that you found that video useful.
(Btw track that I used was accidentally found on YouTube - one drummer recorded his "Top 10 Joey Jordison (ex. Slipknot) drum beats", and the audio quality was quite good for YouTube.)
As you also noticed, there are no many videos showing how actually tapped horns sound with more demanding material.
I was searching quite extensively for both "THAM 12" & "Keystone Sub" videos but couldn't find much good quality videos.
When I recorded my video clip (double bass on drum), I was adjusting phase & crossover between two THAM 12 and Keystone Sub, so that is the reason why I used track with quick drums, as big phase mismatch will not sound well defined & clear.
Btw, I like your choice for test tracks - Dream Theater is definitely demanding material for correct reproduction, I will try these tracks as well.
Thanks for the info! I've started a thread for my speakers to reproduce the type of music I like while having a high WAF (wife acceptance factor). I started looking at the intensity of where most power is needed and it seems 40-350hz is where most of the intensity is. Bass drum/snare/bass guitar is what plays in that area. I would consider a combination of a midbass and low tapped horn, but am concerned with crossing at 90hz. Tight bass drums seem to need the 35hz-110hz range for music that I analyzed. Have you found that you have been able to successfully integrate the two cabinets at that frequency to preserve the "tightness" of that frequency region? Link here if you are interested: https://www.diyaudio.com/community/...mic-speaker-system-build.405314/#post-7502856
Dr. Suad:
Regarding your question (how to combine two different horns for tight bass):
These are my first tapped horns => I was experimenting with fullrange drivers & BLH's (Back Loaded Horns), but THAM 12 and Keystone are first tapped horns that I've made,
Please note that my original intention was to use THAM 12 (for 50-130Hz range) with line arrays (from 130Hz to 20kHz), and that Keystone Sub was added later, just to add lowest octave (which is not missing in all program material).
That said, when you look frequency range that THAM 12 covers (50-130Hz) and that Keystone covers (35-90hz), you can notice that they have relatively large overlap => so if I want I can combine them even without crossover ( so I get bump on the frequency range which all three boxes are playing) , or I can choose crossover frequency so that each driver gets approximately one octave range (Keystone from 35-65 Hz, THAM 12 from 65-130Hz).
Now If I wanted to extract maximum mid bass performance, I would go different way....I would probably have to use new cabinets dedicated for midbass => something that could cover range from 130Hz to 350Hz ideally, with sufficient sensitivity to match THAMs and Keystone (around 100dB/1W).
(NOTE. In fact I was thinking about that recently, and maybe could try to make one closed cabinet with couple of high efficiency 12" drivers, just to see if there is any audible improvement.)
Btw, thanks for the link to your project - this looks quite interesting!
My opinion related to tight bass from two different sources (horns in your & mine case) is that if the crossover frequency is sufficiently low, and both drivers are correctly phase aligned, it should be difficult to identify exact emitting source for such low frequency sound.
When you mentioned home audio project, I must admit that at home I am not listening to horn based system - I had BLH's but moving towards better & much larger system would decrease my WAF to minimum, so few years ago I assembled LX mini kit and added two small closed subs, and this is my main system now:
The crossovers on this systems are adjusted like this:
a) Subwoofer: from 25Hz to 60Hz,
b) Woofer: from 60Hz to 700 Hz,
c) Fullrange: from 700 Hz to 20kHz
With these crossover frequencies, all drum recordings that I have sound tight and dynamic => closed cabinets on subwoofer & woofer certainly help with transient response.