Success!!
I reached my goal of 103 db evenly. An eminence 3015lf in a 5.5 cu ft cabinet to eminence specs, vs the last Tapped horn I built, the CTH1524 also with a 3015lf. The TH beats the direct radiator by at least 3 db everywhere but a very narrow band at 115hz.
The built box actually appears to have exceeded the hornresp expectations. It was a pain to build. Ugggh O.K. six more to go.
One cab on a 6300 sq ft room did a nice job, 126 db at the cabinet
and 93+ at 80 feet (I didn't have a bigger amp handy).
I would suggest 4 for a room that size, 6 if you are loud.
I'll post details shortly.
Pics in the same place scroll down
http://www.screamersusa.com/TAPPED.html
I reached my goal of 103 db evenly. An eminence 3015lf in a 5.5 cu ft cabinet to eminence specs, vs the last Tapped horn I built, the CTH1524 also with a 3015lf. The TH beats the direct radiator by at least 3 db everywhere but a very narrow band at 115hz.
The built box actually appears to have exceeded the hornresp expectations. It was a pain to build. Ugggh O.K. six more to go.
One cab on a 6300 sq ft room did a nice job, 126 db at the cabinet
and 93+ at 80 feet (I didn't have a bigger amp handy).
I would suggest 4 for a room that size, 6 if you are loud.
I'll post details shortly.
Pics in the same place scroll down
http://www.screamersusa.com/TAPPED.html
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.
Because most haven't a clue of
what/when/how. They think if you just push the EQ all the way up and have the meter full red it will be better.
Specially here in the states.
Which is why you see crap Pioneer mixers everywhere. Those things are complete junk.
I always had a label that read:
"You see RED, turn it down!"
I miss my Bi Amp!
what/when/how. They think if you just push the EQ all the way up and have the meter full red it will be better.
Specially here in the states.
Which is why you see crap Pioneer mixers everywhere. Those things are complete junk.
I always had a label that read:
"You see RED, turn it down!"
I miss my Bi Amp!
CH1524 vs Direct radiator difference shown.
140hz +9db
130hz +12db
120hz +9db
115hz +0 db
110hz +4db
105hz +3db
100hz +4db
95hz +5db
90hz +4db
80hz +3db
70hz +2db
60hz +7db
55hz +5db
50hz +4db
45hz +3db
40hz +4db
38hz +4db
The direct radiator had the advantage as it did not have the coil as per eminence's box design. The TH still beat it.
What's nice is you can take them up higher than 100hz if you need to, and you don't need a fancy grille. You can make a PET screen mesh grille for asthetics and toss a heavy round grille over the driver. Also the magnet is not exposed to ...RAIN.
So much for that other box I'm now glad I didn't build more of.
WARNING to Newbies... Use your test gear to verify what you "think" you hear. I almost bailed on this box because it didn't seem to have as much low end as my previous boxes. It actually has more low end, but because there is much more mid bass to play with, the perception is that it's weak. It's actually balanced pretty well for a DIY hacker. You can actually hear the damn bass player clearly in the mix... aaahhh...
All that fancyesque tapering fixes the upper bass problems and smooths out the 70 hz or so cancellations caused by parallel walls. No more big holes.
The CTH1524 is the HTH15 redone as a 24inch wide box.
When exporting, you need S1 to be 14cm high, and s2 to be 15cm high to fit the driver with a tiny bit of circulation space.
140hz +9db
130hz +12db
120hz +9db
115hz +0 db
110hz +4db
105hz +3db
100hz +4db
95hz +5db
90hz +4db
80hz +3db
70hz +2db
60hz +7db
55hz +5db
50hz +4db
45hz +3db
40hz +4db
38hz +4db
The direct radiator had the advantage as it did not have the coil as per eminence's box design. The TH still beat it.
What's nice is you can take them up higher than 100hz if you need to, and you don't need a fancy grille. You can make a PET screen mesh grille for asthetics and toss a heavy round grille over the driver. Also the magnet is not exposed to ...RAIN.
So much for that other box I'm now glad I didn't build more of.
WARNING to Newbies... Use your test gear to verify what you "think" you hear. I almost bailed on this box because it didn't seem to have as much low end as my previous boxes. It actually has more low end, but because there is much more mid bass to play with, the perception is that it's weak. It's actually balanced pretty well for a DIY hacker. You can actually hear the damn bass player clearly in the mix... aaahhh...
All that fancyesque tapering fixes the upper bass problems and smooths out the 70 hz or so cancellations caused by parallel walls. No more big holes.
The CTH1524 is the HTH15 redone as a 24inch wide box.
When exporting, you need S1 to be 14cm high, and s2 to be 15cm high to fit the driver with a tiny bit of circulation space.
FlipC said:
Funny you should mention that.... I guess if the driver is hanging into the mouth it's called a tapped horn, if it is mounted facing into the mouth its a scoop. Confuses the hell out of me.
maybe we should call them THOOPS.
Seems to be an ongoing debate in all the forums. It certainly does not sound or behave like a scoop as the scoop fires its driver directly at the audience so no real gain above 80hz. The tapped fires into the mouth and uses the last bit of horn to help the radiator as well.
Best way I've found to use scoops was to cross them at 80hz, flip the phase so the horn is in phase with the tops.
I have a Pair of original genuine JBL double 15 scoops if anyone needs them. I've had 18's that look like this box, but this box kills them.
It didnt. I took the HTH15 and altered it for 24 inches. Then I measured the driver's clearances to get a sense of how small I could make a chamber to put it in.
On the HTH it was modeled as a throat chamber big enough to house the driver inverted inside the chamber. So the HTH was developed as a big throat firing into the tapped horn. I didn't compensate for the driver displacement in horn resp.
In the HTH I added styrofoam blocks to shrink the chamber while testing with an rta.
The CTH used the HTH hornresp as a setup and instead of the chamber I used the normal method of s1/s2 and exported it such that s1 and s2 were high enough to clear the driver.
In order to adjust the last stage of the horn, s2 and s3 are the main horn body at 196cm. This means from your last turn at s3 through the driver and mouth can stay as one unit all tracking together. you then tweak s3 and s2 to get a horn that will fit.
I'm willing to bet that if I invert the driver, add a phase plug, I'll probably be able to make it work either way.
There is a dip at two points with the basket hanging in the mouth versus the driver facing the mouth. The sound is very different as well. The driver facing the mouth is much clearer and easy to listen to while allowing you to go higher on the crossover.
A lot of South American music is easier to deal with with the subs crossed over at 140.
It "sounds" a little bassier with the drivermagnet in the mouth but its actually NOT. Its a touch lower below 50 and a dip appars at 65-70hz so it seems to have more bass. This box was designed to be the most practical beat the hell out of it DIY TH I could come up with for my use. That's why I wanted to try the driver inside the box.
On the HTH it was modeled as a throat chamber big enough to house the driver inverted inside the chamber. So the HTH was developed as a big throat firing into the tapped horn. I didn't compensate for the driver displacement in horn resp.
In the HTH I added styrofoam blocks to shrink the chamber while testing with an rta.
The CTH used the HTH hornresp as a setup and instead of the chamber I used the normal method of s1/s2 and exported it such that s1 and s2 were high enough to clear the driver.
In order to adjust the last stage of the horn, s2 and s3 are the main horn body at 196cm. This means from your last turn at s3 through the driver and mouth can stay as one unit all tracking together. you then tweak s3 and s2 to get a horn that will fit.
I'm willing to bet that if I invert the driver, add a phase plug, I'll probably be able to make it work either way.
There is a dip at two points with the basket hanging in the mouth versus the driver facing the mouth. The sound is very different as well. The driver facing the mouth is much clearer and easy to listen to while allowing you to go higher on the crossover.
A lot of South American music is easier to deal with with the subs crossed over at 140.
It "sounds" a little bassier with the drivermagnet in the mouth but its actually NOT. Its a touch lower below 50 and a dip appars at 65-70hz so it seems to have more bass. This box was designed to be the most practical beat the hell out of it DIY TH I could come up with for my use. That's why I wanted to try the driver inside the box.
djk said:
An interesting failure mechanism, normally the cone collapses or tears away from the surround. I guess that on negative excursions the coil tries to pull the cone/dustcap into the cabinet, the cabinet resists this by lowering air pressure in front of the cone, and the pressure difference under the dustcap because of the pole vent sucks the dustcap off.
Any enclosure where the cone excursion is greatly reduced by the enclosure (BL opposed by air pressure) can suffer this kind of failure (or other cone/surround failures), but the wider range of frequencies that this happens over (and the bigger the excursion reduction) the more likely failure is.
A driver in a reflex box will fail if driven repeatedly near the box resonance, a bandpass near either of the box resonances, or a horn over most of the passband. Higher compression ratio reduces the excursion further so the problem gets worse.
So if you want to rate enclosures on order of driver destructiveness, you get:
closed box -- best (except for Xmax limit, obviously)
reflex (bad near box resonance, OK elsewhere)
dual chamber bandpass (very bad at some frequencies, OK at others)
low CR horn (bad at all frequencies)
high CR horn (very bad at all frequencies)
Ian
FlipC said:
Drunk idiots, kids poking cabs with pencils, rain, dog pee, humidity coupled with direct sunlight, I like to avoid those as much as possible.
My favorite speaker saver......Scotchguard, orange top. Not too good for the back of the speaker cause it will get into the coil so don't get any ideas guys. Scotchguard foward facing cones only.
That's Another reason why I wanted the driver inside the box.
I use True RTA, an Amber 3501, and a rat shack db meter, a couple of Fluke multimeters, A beheringer ecm test mic but I use an old DAK condenser most of the time. They are both pretty close but the dak plugs right into the laptop. Since I don't have an anecolic chamber or any other fancy toys to work with these will do.
The amber has a VERY stable oscillator.
I test overall with the rta at 1/6 or 1/12th octave because 1/3rd hides too much. I also test with the rat shack and the amber oscillator to see at pure frequencies what the box is doing.
I've found that the oscillator test is much better for my own head as the results are usually clearer than the rta. They both have their use.
As far as cooling, these will eventually get 4015's as I prefer the sound of an old fasioned big magnet over an NDYM.
Sounds more articulate to my ear. Cooling wont be an issue with those.
As far as plots etc, what I've already posted is where I am now.
No sense posting the Rta stuff as it's on another computer and, I am altering the box to make it easier to build so I'll have to retest a finished one anyway. The CTH1524 is the only one I am working on at this point as it meets the requirements I was going for. I tweaked the bulldog but have not checked it yet (The smaller Jbell box).
I forfot to mention that the oscillator and your ear test shows the phase problems inside the box very clearly that the rta doe not. I can then play with ramps etc to try to fix it or quickly realize the box is a failure and cease wasting time on it . A sweep would work too but you really need to know what frequencies are acting up.
Perhaps someone knows of a freeware sweep oscillator program.
Perhaps someone knows of a freeware sweep oscillator program.
Did you ever experiment with adding inductance to the driver in any of these cabinets to flatten out response?
I had to add a couple mh of inductance to my cab to flatten out the 60-70 dip, and I figure you'll probably have to do something similar on your smaller version of my cabinet. A thought, since the variations of cabinet design affect overall impedance of the cabinet/driver combination... does adding a couple mh of inductance really accomplish the same thing (to your ear) with a simpler cabinet with parallel surfaces, as your much more complicated cabinet? or is it a case where the added inductance flattens out the spl response, but the sound is night/day different?
Also.. side note, kinda unrelated.. Hornresp shows me why adding inductance/resistance that I put on my dual T18 made things so nice. Amazing what the little 2421's do with just a little added help...
I had to add a couple mh of inductance to my cab to flatten out the 60-70 dip, and I figure you'll probably have to do something similar on your smaller version of my cabinet. A thought, since the variations of cabinet design affect overall impedance of the cabinet/driver combination... does adding a couple mh of inductance really accomplish the same thing (to your ear) with a simpler cabinet with parallel surfaces, as your much more complicated cabinet? or is it a case where the added inductance flattens out the spl response, but the sound is night/day different?
Also.. side note, kinda unrelated.. Hornresp shows me why adding inductance/resistance that I put on my dual T18 made things so nice. Amazing what the little 2421's do with just a little added help...
Hi Scott! I really appreciate you sharing your efforts. When you
are happy with the results, I hope you will share the construction
details.
I'm more comfortable with geometry than electronics, so I have
contributed by creating/documenting horn foldings. To date, I
have posted 6 sets of plans, including a version of Jim Bell's big
horn. I am also a builder, having built a single fold TH using the
Kappalite 3015LF and a double fold TH using the LAB12.
Your comment:
"All that fancyesque tapering fixes the upper bass problems and smooths out
the 70 hz or so cancellations caused by parallel walls."
Won't the attached mod eliminate any reflection problems with Jim's big horn?
are happy with the results, I hope you will share the construction
details.
I'm more comfortable with geometry than electronics, so I have
contributed by creating/documenting horn foldings. To date, I
have posted 6 sets of plans, including a version of Jim Bell's big
horn. I am also a builder, having built a single fold TH using the
Kappalite 3015LF and a double fold TH using the LAB12.
Your comment:
"All that fancyesque tapering fixes the upper bass problems and smooths out
the 70 hz or so cancellations caused by parallel walls."
Won't the attached mod eliminate any reflection problems with Jim's big horn?
Attachments
Life has been busy getting in my way. Sorry folks.
No major updates as the drivers are impatiently awaiting thier boxes.
DON, That should help for a sub only application. The problems I encountered only went away after I minimized the side wall parallel surfaces. Getting most of the taper is easy if you do it in the center of the box so it doubles as a central support. The problem is getting from your drivers entry point to a split horn while keeping it tapered around the turns. This is much worse on the CTH which is where I am hung up waiting for dedicated time to work out the geometry and buildability of the first stages.
HK The CTH doesn't mind the JBL. I did that more as a backup issue to keep a cabinet running if one blows. The Jbl has about 2-3 db less output and I would monitor it carefully. The 2226 may work better as it has more xmax. My Jbls are back in thier double bins for now and will be sold to buy more TH drivers once the first 4 CTH cabs are up.
Thanks JB for waking me up....
No major updates as the drivers are impatiently awaiting thier boxes.
DON, That should help for a sub only application. The problems I encountered only went away after I minimized the side wall parallel surfaces. Getting most of the taper is easy if you do it in the center of the box so it doubles as a central support. The problem is getting from your drivers entry point to a split horn while keeping it tapered around the turns. This is much worse on the CTH which is where I am hung up waiting for dedicated time to work out the geometry and buildability of the first stages.
HK The CTH doesn't mind the JBL. I did that more as a backup issue to keep a cabinet running if one blows. The Jbl has about 2-3 db less output and I would monitor it carefully. The 2226 may work better as it has more xmax. My Jbls are back in thier double bins for now and will be sold to buy more TH drivers once the first 4 CTH cabs are up.
Thanks JB for waking me up....