Anthony,
I can run some cases with a cabinet that is 3 in deeper to see what the additional Vb will do. It certainly will bring the bass extension lower but how much we will have to wait and see. I already tried extending the front chamber by folding it one more time and wrapping it around the back - no luck there as it only made the sharp notch deeper but did not affect low end extension.
Did you move the vent with it?
Off in comparison land,
This from a scrap of paper on my desk:
T15 = 22" x 20" x 23" Smallest
K15 = 33" x 22" x 18" (T15 +8")
SS15 = 22" x 24" x 30" (T15 +8")
THAM15 = 22" x 19" x 27" (T15 +3")
The SS15 and THAM15 both start to fall off below 50hz and are down -5dB at 40hz and then -15dB at 30. Graphs suggest they only reach cleanly up to 150 and then a messy rising W notch shows up before they nosedive into an empty swimming pool at 280hz
Interestingly the SS15 made of lighter plywood is probably the same weight as the T15 (unless 1/2 ply is acceptable for some of the T15 panels). Also JBell says his SS15 sacrifices a bit of efficiency to achieve it's small size and is basically just over ~100dB 1w/1m. It's probably useable up to 230hz or so even though plots show it's a jumpy mess from 150 to 270.
Summary...
- THAM, SS15, K15, T15... are all hanging out around 100dB/1watt/1m at their LF corner.
- Tapped horns don't reach very high (at the max 250Hz) and so require a midhorn and tophorn.
- The T15 makes a 2 way PA possible (large horn mated on top like Altec mr945, JBL 2360a, Synergy clone or some other fun)
T15 seems most suitable for lightweight outdoor PA as it can cross high and void unnecessary lower mid box. Tapped horns in this category are flat to 50hz. One other thought, having higher frequency transients coming from the same woofer element that is producing the kick gives us real phase and time alignment.It's likely some realism is lost when a TH is mated with a midbass cab (unless extreme care of crossover, time alignment and positioning is undertaken).
K15 for comparison with T15
I wanted to see what the performance of the K15 is with the Kilomax 15, Kappa 15A, and B&C 15HCX76 in similar setting of a large stadium (walls really far away), and I have added damping into the back chamber. There is no doubt that the K15 is a time-tested design if you look at the incredibly wide and flat bass shelf which makes it ideal for crossing over higher (around 1.25 kHz - perfect for a coaxial horn).
- SPL vs Freq for Kilomax 15
- SPL vs Freq for Kappa 15A
- SPL vs Freq for B&C 15HCX76
- SPL vs Freq for Kilomax 15 with 300 watts input at 6 meters away
- Cone displacement for Kilomax 15 with 300 watts input
At 300 watts power, the linear xmax of the Kilomax 15 driver is reached at about 50 Hz. The efficiency of the K15 is really incredible when paired with pro audio drivers.
I wanted to see what the performance of the K15 is with the Kilomax 15, Kappa 15A, and B&C 15HCX76 in similar setting of a large stadium (walls really far away), and I have added damping into the back chamber. There is no doubt that the K15 is a time-tested design if you look at the incredibly wide and flat bass shelf which makes it ideal for crossing over higher (around 1.25 kHz - perfect for a coaxial horn).
- SPL vs Freq for Kilomax 15
- SPL vs Freq for Kappa 15A
- SPL vs Freq for B&C 15HCX76
- SPL vs Freq for Kilomax 15 with 300 watts input at 6 meters away
- Cone displacement for Kilomax 15 with 300 watts input
At 300 watts power, the linear xmax of the Kilomax 15 driver is reached at about 50 Hz. The efficiency of the K15 is really incredible when paired with pro audio drivers.
Attachments
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T15 with added 3 in depth
I added 3 inches to the depth of the T15 cabinet to give more Vb. I also increased the length of the internal vent by 4 inches to 10.5 inches long. This provides a bit more bass extension which is now 100 dB at 55 Hz and is down 3 dB at 50 Hz. This should be able to capture the punch of a 50 Hz kick drum better with only a nominal gain in cabinet size.
- SPL vs Freq for 2.83V input at 1 meter
- Impedance
- Cone displacement
I added 3 inches to the depth of the T15 cabinet to give more Vb. I also increased the length of the internal vent by 4 inches to 10.5 inches long. This provides a bit more bass extension which is now 100 dB at 55 Hz and is down 3 dB at 50 Hz. This should be able to capture the punch of a 50 Hz kick drum better with only a nominal gain in cabinet size.
- SPL vs Freq for 2.83V input at 1 meter
- Impedance
- Cone displacement
Attachments
T15 with Added 3 in depth & Extra Fold on TL
I added an extra fold on the back of the T15 Grande (+3in) so the 3.5 in tall channel makes a 90 deg turn that tapers to 1.75 in at the bottom of the cabinet. This seems to bring the bass extension solidly into the 50 Hz territory at the expense of a few dB in efficiency and there is a slight sag (-1.5 dB at 120 Hz) in the response indicative of over-extending a driver's bass response. So this configuration adds +6.5 in to the depth of the cabinet.
I added an extra fold on the back of the T15 Grande (+3in) so the 3.5 in tall channel makes a 90 deg turn that tapers to 1.75 in at the bottom of the cabinet. This seems to bring the bass extension solidly into the 50 Hz territory at the expense of a few dB in efficiency and there is a slight sag (-1.5 dB at 120 Hz) in the response indicative of over-extending a driver's bass response. So this configuration adds +6.5 in to the depth of the cabinet.
Attachments
from Wayne Green's recollections, K15 was developed and finalized in the summer of 1951. Good bracing of K15's wings and rear panel help. Carl braced one set of his K15 per Cetec-Gauss 5181 plan
I would think Fb on T15 to be in the 40's (?) K15 has Fb on the upper 40's and a near-field cone (?) null of ~37Hz.
I would think Fb on T15 to be in the 40's (?) K15 has Fb on the upper 40's and a near-field cone (?) null of ~37Hz.
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Regarding the now familiar Karlson notches, user IG over at audioasylum.com writes:
"The more extended Karlsons can make it up to ~350Hz before that first big dip. The little SK8 is one of them and so is one of freddyi's big 18" koupler IIRC. There is often a second large dip about an octave above the first one and a peak in-between if you're not lucky. I call this the "W" effect. Finding a way to keep these narrow and below 10dB in magnitude is a good thing for fullrange use. There can still be some chopiness above this, but of much less consequence IMO. You can probably coax up to 3 octaves of relatively smooth gain from ideal koupler/driver combos, starting at ~50z for K15, ~60Hz for K12 and ~70Hz for SK8. You ideally want to keep the front chamber tuning, given by a quarter-wave of ~95% it's vertical dimension, below the driver's mass-corner frequency to avoid upper-bandwidth peaking, which can be more offensive than the W effect itself."
-IG
"The more extended Karlsons can make it up to ~350Hz before that first big dip. The little SK8 is one of them and so is one of freddyi's big 18" koupler IIRC. There is often a second large dip about an octave above the first one and a peak in-between if you're not lucky. I call this the "W" effect. Finding a way to keep these narrow and below 10dB in magnitude is a good thing for fullrange use. There can still be some chopiness above this, but of much less consequence IMO. You can probably coax up to 3 octaves of relatively smooth gain from ideal koupler/driver combos, starting at ~50z for K15, ~60Hz for K12 and ~70Hz for SK8. You ideally want to keep the front chamber tuning, given by a quarter-wave of ~95% it's vertical dimension, below the driver's mass-corner frequency to avoid upper-bandwidth peaking, which can be more offensive than the W effect itself."
-IG
Anthony Bisset,
Are you going to do the test build with the extended 3 in cabinet, or even the one with the longer TL front chamber? I think this could work out really well - what are you going to use as the tweeter? A CD/horn combo?
Are you going to do the test build with the extended 3 in cabinet, or even the one with the longer TL front chamber? I think this could work out really well - what are you going to use as the tweeter? A CD/horn combo?
When I first modeled the K15 in Akabak, I had no idea what the repsonse would look like and IG was the one who told me that my sim contained the classic W notch - a sign I was on the right track.
I have to admit the the graphs for the Kilomaxx+K15 are amazing!
Like you've pointed out it's very capable and definitely fits the thread title. Such a FR is near perfection lacking only a bit of sub bass. Since Kick drum snap is typically present at ~1Khz the K15 provides a single driver reproduction source for LF & low mids percussion I can see why Freddi has been vocal about them for so long! Obviously the phase response and combing is another matter.
Even so the K15 is 5 linear inches larger than our +3" T15 Grande (and 8" over our base T15), & our T15 stacks better without being precarious and is giving us extended LF (and I like the visual aesthetic better although I'm skeptical of front chamber optimizations in the T15). All this feels like ample justification for our Karlson sub.
Returning to the T15, the +3" grande version is looking good but I do wish we knew how to move the notch down to cut at 250hz (if the notch had a rising edge starting at 180-190hz rising to 220hz before dipping at 250hz and then bouncing back with some overshoot near 280-300hz)... Rather than a response aberration that needs corrective EQ we could hijack it as a subtle clarifying EQ. It would reduce common buildup/mud @ 250hz while the gain at 200hz would emphasize guitar and bass separation and the gain between 280hz and 300hz increases bass note presence with boost of upper harmonics and female voices would benefit as well.
Any ideas why it's so low on a K15 and so high on the T15?
The K15 notch in your graph is around 170hz.
That's a QW of 19.5"
1/2WL 39"
1W 78"
The T15-Grande notch is centered around 329hz.
That's a QW of 10.25"
1/2WL 20.50"
1W 41"
Did you ever read about the cost no object basement architected with 3 large concrete front horns? It was designed to reproduce drums at realistic levels. The designer was a very competent engineer (holding patents in electronics and maybe aerospace). He eventually concluded that comb filtering in the HF was desirable and even wrote enhancement software for reproduction systems... He was very solid in the math/engineering department so I haven't discounted his findings and part of me thinks the Koupler provides a similar HF combing artifact in addition to shaping the good polar response.
As far as which one to build, I'm still meditating... I remain committed to building a T15 testbox for comparison to one or more of your graphs. Really looking forward to testing your akabak model out. I'm leaning towards the T15-Grande. +3" I can handle, but at +6.5" I feel like we're starting to impact portability.
For the PA I'm thinking to crossover at ~500hz to a JBL 2360 (or on the cheap to an Altec MR945). Someday when weight/portability isn't so important I'm thinking to try a community M4 with custom horn crossed at 300-350hz. &/or a 90deg Synergy horn tailored for above 300hz. I could probably get away with a Synergy+T15 for studio use.
Like you've pointed out it's very capable and definitely fits the thread title. Such a FR is near perfection lacking only a bit of sub bass. Since Kick drum snap is typically present at ~1Khz the K15 provides a single driver reproduction source for LF & low mids percussion I can see why Freddi has been vocal about them for so long! Obviously the phase response and combing is another matter.
Even so the K15 is 5 linear inches larger than our +3" T15 Grande (and 8" over our base T15), & our T15 stacks better without being precarious and is giving us extended LF (and I like the visual aesthetic better although I'm skeptical of front chamber optimizations in the T15). All this feels like ample justification for our Karlson sub.
Returning to the T15, the +3" grande version is looking good but I do wish we knew how to move the notch down to cut at 250hz (if the notch had a rising edge starting at 180-190hz rising to 220hz before dipping at 250hz and then bouncing back with some overshoot near 280-300hz)... Rather than a response aberration that needs corrective EQ we could hijack it as a subtle clarifying EQ. It would reduce common buildup/mud @ 250hz while the gain at 200hz would emphasize guitar and bass separation and the gain between 280hz and 300hz increases bass note presence with boost of upper harmonics and female voices would benefit as well.
Any ideas why it's so low on a K15 and so high on the T15?
The K15 notch in your graph is around 170hz.
That's a QW of 19.5"
1/2WL 39"
1W 78"
The T15-Grande notch is centered around 329hz.
That's a QW of 10.25"
1/2WL 20.50"
1W 41"
Did you ever read about the cost no object basement architected with 3 large concrete front horns? It was designed to reproduce drums at realistic levels. The designer was a very competent engineer (holding patents in electronics and maybe aerospace). He eventually concluded that comb filtering in the HF was desirable and even wrote enhancement software for reproduction systems... He was very solid in the math/engineering department so I haven't discounted his findings and part of me thinks the Koupler provides a similar HF combing artifact in addition to shaping the good polar response.
As far as which one to build, I'm still meditating... I remain committed to building a T15 testbox for comparison to one or more of your graphs. Really looking forward to testing your akabak model out. I'm leaning towards the T15-Grande. +3" I can handle, but at +6.5" I feel like we're starting to impact portability.
For the PA I'm thinking to crossover at ~500hz to a JBL 2360 (or on the cheap to an Altec MR945). Someday when weight/portability isn't so important I'm thinking to try a community M4 with custom horn crossed at 300-350hz. &/or a 90deg Synergy horn tailored for above 300hz. I could probably get away with a Synergy+T15 for studio use.
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that was Richard Burwen's install - I believe there were also two rear horns (?) - in retrospect he wished the concrete had been thicker. At one point it had many Cerwin Vega Dhorms as the tweeter arrays. http://burwenaudio.com/
mic on ground - effect upon notch depth of tilting K15 so its baffle is perpendicular to the ground
Onken style reflex notch vs K15 notch - the yellow trace is K15 tilted til its baffle was perpendicular to the ground
effect at ground level on the reflex when inverting the cabinet
mic on ground - effect upon notch depth of tilting K15 so its baffle is perpendicular to the ground
An externally hosted image should be here but it was not working when we last tested it.
Onken style reflex notch vs K15 notch - the yellow trace is K15 tilted til its baffle was perpendicular to the ground
An externally hosted image should be here but it was not working when we last tested it.
effect at ground level on the reflex when inverting the cabinet
An externally hosted image should be here but it was not working when we last tested it.
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I'd like an explanation of why a near-field measurement of a woofer-cone in a K15 bulk coupler without front shelf seems to show a displacement null "below" system Fb
here's an old near-cone graph of an Eminence cast-frame 15" coax in K15 - I think system Fb by input impedance would be around 48Hz or so --- but the null comes in around 37Hz -why? When doing sine testing of K15 at 20vrms/36Hz versus an "equivalent bass reflex" (BR the size of K15's rear chamber with similar tuning), K15 had about 1/3 the cone excursion of the reflex which was tuned with two 4"ID pvc ducts.
this was an Eminence 18 with mms ~103g, fs ~30 and qts ~0.26 -- the coupler really didn't play as smooth as K15 but gave a feel for what might be done "next" - it had plenty of power and as a 2-way with Karlson X15 k-tube on top was much better than any FR I've heard for dynamics.
If anyone thinks a 12LTA in a reflex has "impact" then they would die of fright at K15 or similar.
if one looks carefully, the two 4.5" holes acting as ports placement can be seen.
this one-sheet K-type was originally cut for a 15 and I opened it up for an 18.
It induced my first chest pains up close - lol
here's an old near-cone graph of an Eminence cast-frame 15" coax in K15 - I think system Fb by input impedance would be around 48Hz or so --- but the null comes in around 37Hz -why? When doing sine testing of K15 at 20vrms/36Hz versus an "equivalent bass reflex" (BR the size of K15's rear chamber with similar tuning), K15 had about 1/3 the cone excursion of the reflex which was tuned with two 4"ID pvc ducts.
An externally hosted image should be here but it was not working when we last tested it.
this was an Eminence 18 with mms ~103g, fs ~30 and qts ~0.26 -- the coupler really didn't play as smooth as K15 but gave a feel for what might be done "next" - it had plenty of power and as a 2-way with Karlson X15 k-tube on top was much better than any FR I've heard for dynamics.
If anyone thinks a 12LTA in a reflex has "impact" then they would die of fright at K15 or similar.
An externally hosted image should be here but it was not working when we last tested it.
if one looks carefully, the two 4.5" holes acting as ports placement can be seen.
this one-sheet K-type was originally cut for a 15 and I opened it up for an 18.
It induced my first chest pains up close - lol
An externally hosted image should be here but it was not working when we last tested it.
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It might be the shorter length of the K aperture relative to length of TL formed by front chamber.
here's a custom Eminence with 5 inch voice coil and 160 ounce magnet slug- wonder if that large coil vs the spider compromises linearity? - it might help a bit with thermal compression. I don't think the picture they show is correct - but they are a good company - a "T18" could be a possibility - might not be any rebuild parts for it unless directly from Eminence
link seems to poop out - just search for TSG 18
TSG 18 inch Subwoofer 5 inch Voice Coil Free Shipping Any Reasonable Offers | eBay
TSG 18-250 18" Subwoofer
with 5 Inch (125 mm)Voice Coil
Call 801-771-1820 with any questions.
SPECIFICATION
Nominal Basket Diameter 18", 460mm
Nominal Impedance* 8 ohms
Power Rating
RMS Watts 800W
Music Program 1600W
Resonance 35Hz
Usable Frequency Range 34Hz-3.7kHz
Sensitivity*** 99 db
Magnet Weight 160 oz.
Gap Height
Voice Coil Diameter 5", 125 mm
THIELE & SMALL PARAMETERS
Resonant Frequency (fs) 35 Hz
DC Resistance (Re) 5.0 ohms
Inductance 3.0mh
Mechanical Q (Qms) 9.21
Electromagnetic Q (Qes) .29
Total Q (Qts) .28
Compliance Equivalent Volume (Vas) 249.4 liters / cu.ft.
Peak Diaphragm Displacement Volume (Vd) cc
Mechanical Compliance of Suspension (Cms) mm/N
BL Product (BL) 24.3 T-M
Diaphram Mass inc. Airload (Mms) 148 grams
Efficiency Bandwidth Product (EBP)
Maximum Linear Excursion (Xmax) mm
Surface Area of Cone (Sd) cm2
Maximum Mechanical Limit (Xlim) 12 mm
MOUNTING INFORMATION
Recommended Enclosure
Sealed
Vented
Overall Diameter
Baffle Hole Diameter
Front Sealing Gasket Fitted as standard
Rear Sealing Gasket Fitted as standard
Mounting Holes Diameter 0.28", 7.1mm
Mounting Holes B.C. D.
Depth
Net Weight 35.7 lbs.,
Shipping Weight 73.9 lbs.,
MATERIALS OF CONSTRUCTION
Coil Construction Aluminum voice coil
Coil Former Polyimide former
Magnet Composition Ferrite magnet
Core Details Vented core
Basket Materials Die-cast aluminum basket
Cone Composition Paper Cone
Cone Edge Composition Cloth cone edge
Dustcap Composition Solid composition paper dust cap
link seems to poop out - just search for TSG 18
TSG 18 inch Subwoofer 5 inch Voice Coil Free Shipping Any Reasonable Offers | eBay
TSG 18-250 18" Subwoofer
with 5 Inch (125 mm)Voice Coil
Call 801-771-1820 with any questions.
SPECIFICATION
Nominal Basket Diameter 18", 460mm
Nominal Impedance* 8 ohms
Power Rating
RMS Watts 800W
Music Program 1600W
Resonance 35Hz
Usable Frequency Range 34Hz-3.7kHz
Sensitivity*** 99 db
Magnet Weight 160 oz.
Gap Height
Voice Coil Diameter 5", 125 mm
THIELE & SMALL PARAMETERS
Resonant Frequency (fs) 35 Hz
DC Resistance (Re) 5.0 ohms
Inductance 3.0mh
Mechanical Q (Qms) 9.21
Electromagnetic Q (Qes) .29
Total Q (Qts) .28
Compliance Equivalent Volume (Vas) 249.4 liters / cu.ft.
Peak Diaphragm Displacement Volume (Vd) cc
Mechanical Compliance of Suspension (Cms) mm/N
BL Product (BL) 24.3 T-M
Diaphram Mass inc. Airload (Mms) 148 grams
Efficiency Bandwidth Product (EBP)
Maximum Linear Excursion (Xmax) mm
Surface Area of Cone (Sd) cm2
Maximum Mechanical Limit (Xlim) 12 mm
MOUNTING INFORMATION
Recommended Enclosure
Sealed
Vented
Overall Diameter
Baffle Hole Diameter
Front Sealing Gasket Fitted as standard
Rear Sealing Gasket Fitted as standard
Mounting Holes Diameter 0.28", 7.1mm
Mounting Holes B.C. D.
Depth
Net Weight 35.7 lbs.,
Shipping Weight 73.9 lbs.,
MATERIALS OF CONSTRUCTION
Coil Construction Aluminum voice coil
Coil Former Polyimide former
Magnet Composition Ferrite magnet
Core Details Vented core
Basket Materials Die-cast aluminum basket
Cone Composition Paper Cone
Cone Edge Composition Cloth cone edge
Dustcap Composition Solid composition paper dust cap
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Anthony Bisset,
Not sure if you are interested in getting more bass extension with the T15 (with Kilomax 15 driver) but I simply added 7% more volume to the back chamber and here is what I get: solid extension to 40 Hz and a slight sag in response (-3 dB in the 60 to 100 Hz range). Also there is a deeper notch at 240 Hz. Just putting it out there...
Not sure if you are interested in getting more bass extension with the T15 (with Kilomax 15 driver) but I simply added 7% more volume to the back chamber and here is what I get: solid extension to 40 Hz and a slight sag in response (-3 dB in the 60 to 100 Hz range). Also there is a deeper notch at 240 Hz. Just putting it out there...
Attachments
question to X - how much can one control a potential cavity peak by using a "high aspect" to our K-couplers?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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besides asking how much we can manipulate the front chamber tuning and potential cavity peak with more cavity height, what about a fold-back stub - kinda like T15?
I had a small K-coupler with 80 liter rear chamber to test 18" speakers - as an experiment based on something Ken Lehman did, I added an extra 20 liter chamber to the top-front of the coupler with the following effect upon frequency response. The ports were two 4.5"x4.5" holes at the top of the port board. The extra chamber fed through an ~50 sq.in. slot at the top - so the vents were "below" the fold back section rather than feeding through it per T15.
one can see in this case there was some tradeoff - I still have the cabinet loaded and it sports a diy parabolic slot K-tube
did Metro gain some advantages by vent feeding the center of their foldback section?
18" small K-coupler ~K15 overall bulk, 80 liter rear chamber -- 0-45 and 60 degrees off horizontal axis outdoors. It has a fairly tight rear lowpass choke in the rear chamber.
I had a small K-coupler with 80 liter rear chamber to test 18" speakers - as an experiment based on something Ken Lehman did, I added an extra 20 liter chamber to the top-front of the coupler with the following effect upon frequency response. The ports were two 4.5"x4.5" holes at the top of the port board. The extra chamber fed through an ~50 sq.in. slot at the top - so the vents were "below" the fold back section rather than feeding through it per T15.
one can see in this case there was some tradeoff - I still have the cabinet loaded and it sports a diy parabolic slot K-tube
did Metro gain some advantages by vent feeding the center of their foldback section?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
18" small K-coupler ~K15 overall bulk, 80 liter rear chamber -- 0-45 and 60 degrees off horizontal axis outdoors. It has a fairly tight rear lowpass choke in the rear chamber.
An externally hosted image should be here but it was not working when we last tested it.
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Hey X, Thanks for exploring the LF... I liked the extension reached on your T15grandeTL version as it didn't sag as much as this one. When I get to cutting wood I'll mock up a few of these quickly with cheaper ply.
Regarding the Notch at 240hz, I wish! It's at 340hz right in the middle of some prime real-estate... If we ever discover how to move that notch around,,, (I haven't had time to do path-length comparisons between different models, but there should be ample clues present in all of Freddi's measurements & your akabak predictions). I'm pretty confident I would trade 600hz extension for 500 if the notch moved accordingly. This coming from someone who spends ~6 hours a day 6 days a week mixing music in a home studio on mastering grade monitors.
Interesting that Freddie's 18" in a K15+20lt cavity has the notch at 350hz our T15... His 18"K15 without the 20lt cavity moves the notch -20hz to 330hz.
Lots of questions... Really want to make some dust but caught up in finishing a record at the moment.
Anthony Bisset,
I have tried several things and unable to move that notch. I even tried adding a shelf on the front chamber, making the front chamber longer, making the rear chamber volume greater, changing vent length. Maybe Freddi or IG knows what controls the notch location on the T15? If you have some ideas what to try I will see if I can put them in the model.
I have tried several things and unable to move that notch. I even tried adding a shelf on the front chamber, making the front chamber longer, making the rear chamber volume greater, changing vent length. Maybe Freddi or IG knows what controls the notch location on the T15? If you have some ideas what to try I will see if I can put them in the model.
Metro's published response looks pretty good to me compared to reflex
http://img571.imageshack.us/img571/2710/yrkm.jpg
http://img571.imageshack.us/img571/2710/yrkm.jpg