So I decided I've started a few threads on here, but never really got anywhere. Here's a thread where I'll keep track of everything. It'll probably end up a bit like a blog, but discussion is more than welcome.
So far, I have a pair of old EV 15" Deltamax tops with EV DH1a HF units on HP64 horns, with Beyma 15P1200Nd subwoofer drivers as midbass units. Active crossover at ~1.1kHz. I also have a spare set of those Beyma drivers. Having read through Art Welter's compression driver shootout, I'm keen to use the DH1as, as they perform very well. They're stuck on a 2" exit, though - no way of converting them to 1.4" exit.
Below is a thread on what I've been doing so far.
http://www.diyaudio.com/forums/pa-systems/261892-compression-driver-help-please.html
I'd like to widen the dispersion on the HF units, build some subs, and figure out some top speakers that I can actually lift on to stands.
I think I'll go for a set of four (eventually) THAM15s for subs, as they appear to dig low enough for most stuff, while being fairly compact.
For tops, I think a 12" two-way will be okay, provided efficiency is good. My current cabinets are limited at SPL: I'm running a Behringer NU6000DSP (~1200w/ch) for the Beyma 15"s, and hit the limiters during anything bigger than a smallish gig. I suspect I'm simply asking too much of a 2-way system - the free-field low-frequency rolloff comes in around 45Hz, so efficiency is rather low. Groundplane subs would be a much better solution.
After a bit of looking around, I've found these:
RCF - MB12N251
They're available at a reasonable price, and allow the use of a ~40L cabinet tuned to around 80Hz for considerable SPL in the kick region. If anyone has suggestions for a different 12" driver, I'd be interested to find out - those RCFs are the top-end of what I'd want to spend (£100/driver).
I might go for a modular top design, with the mids and HF units in seperate stackable cabinets, for MTM/TMM/TM tops, depending on the SPL needed. A modular design would also make it easy to expand the system later, and, of course make it easy to get those DH1as up high, possibly on a different horn.
I have lots of amplifiers on-hand, and a couple of active crossover/EQ units, so this will be active crossovers and measurements all the way. Preliminary crossover points would be ~1kHz between the DH1a and 12", and ~120Hz from subs to mids.
That's all for now, I'm gonna go make stir-fry.
Chris
So far, I have a pair of old EV 15" Deltamax tops with EV DH1a HF units on HP64 horns, with Beyma 15P1200Nd subwoofer drivers as midbass units. Active crossover at ~1.1kHz. I also have a spare set of those Beyma drivers. Having read through Art Welter's compression driver shootout, I'm keen to use the DH1as, as they perform very well. They're stuck on a 2" exit, though - no way of converting them to 1.4" exit.
Below is a thread on what I've been doing so far.
http://www.diyaudio.com/forums/pa-systems/261892-compression-driver-help-please.html
I'd like to widen the dispersion on the HF units, build some subs, and figure out some top speakers that I can actually lift on to stands.
I think I'll go for a set of four (eventually) THAM15s for subs, as they appear to dig low enough for most stuff, while being fairly compact.
For tops, I think a 12" two-way will be okay, provided efficiency is good. My current cabinets are limited at SPL: I'm running a Behringer NU6000DSP (~1200w/ch) for the Beyma 15"s, and hit the limiters during anything bigger than a smallish gig. I suspect I'm simply asking too much of a 2-way system - the free-field low-frequency rolloff comes in around 45Hz, so efficiency is rather low. Groundplane subs would be a much better solution.
After a bit of looking around, I've found these:
RCF - MB12N251
They're available at a reasonable price, and allow the use of a ~40L cabinet tuned to around 80Hz for considerable SPL in the kick region. If anyone has suggestions for a different 12" driver, I'd be interested to find out - those RCFs are the top-end of what I'd want to spend (£100/driver).
I might go for a modular top design, with the mids and HF units in seperate stackable cabinets, for MTM/TMM/TM tops, depending on the SPL needed. A modular design would also make it easy to expand the system later, and, of course make it easy to get those DH1as up high, possibly on a different horn.
I have lots of amplifiers on-hand, and a couple of active crossover/EQ units, so this will be active crossovers and measurements all the way. Preliminary crossover points would be ~1kHz between the DH1a and 12", and ~120Hz from subs to mids.
That's all for now, I'm gonna go make stir-fry.
Chris
Hi djk,
I removed one of the adapters, and the set of 4 mounting holes normally found on 1.4" exit drivers simply weren't there. I'm not prepared to drill these, as they're my best compression drivers.
Since its a pain to get the driver out of these cabinets, I didn't check the other one.
In other news, I've been toying with the THAM15 design slightly in Hornresp - its possible to shove the rolloff down a few Hz by increasing the height a little, stretching the middle section. I'd like solid 40Hz output so that music such as Invaders Must Die (Prodigy) and Slam (Pendulum) have the bottom end they need.
Chris
I removed one of the adapters, and the set of 4 mounting holes normally found on 1.4" exit drivers simply weren't there. I'm not prepared to drill these, as they're my best compression drivers.
Since its a pain to get the driver out of these cabinets, I didn't check the other one.
An externally hosted image should be here but it was not working when we last tested it.
In other news, I've been toying with the THAM15 design slightly in Hornresp - its possible to shove the rolloff down a few Hz by increasing the height a little, stretching the middle section. I'd like solid 40Hz output so that music such as Invaders Must Die (Prodigy) and Slam (Pendulum) have the bottom end they need.
Chris
I should also add that I have a few coaxial stage monitors, 3x 8"s, and a pair of 12"s. Since the 12"s have decent power handling, I'm going to install some top-hat sockets on them, for use as the mid-high speakers in the setup described above.
Problem is, the frequency response is, quite literally, all over the show:
I took a few measurements, and the positions of the peaks and dips move around a bit, but there's clearly something wrong here. An average looked awful, since the dips were almost complete cancellations at different frequencies/positions. The 8-10kHz haystack definitely needs fixing.
They were done with an ECM8000 close to the front grille, and didn't change much when I swapped the stock compression drivers for some Das Audio M3s (which are fairly nice), so there's clearly a problem with the coaxial horn. Removing the grille didn't change much IIRC.
I have some spare plastic 90x60 horns lying around, that load down to 1kHz, so I was thinking of hacking those down at the throat end to sit in the coaxial speakers, for proper horn loading rather than the short conical expansion that's currently there. Whittling to be done.
Chris
Problem is, the frequency response is, quite literally, all over the show:
An externally hosted image should be here but it was not working when we last tested it.
I took a few measurements, and the positions of the peaks and dips move around a bit, but there's clearly something wrong here. An average looked awful, since the dips were almost complete cancellations at different frequencies/positions. The 8-10kHz haystack definitely needs fixing.
They were done with an ECM8000 close to the front grille, and didn't change much when I swapped the stock compression drivers for some Das Audio M3s (which are fairly nice), so there's clearly a problem with the coaxial horn. Removing the grille didn't change much IIRC.
I have some spare plastic 90x60 horns lying around, that load down to 1kHz, so I was thinking of hacking those down at the throat end to sit in the coaxial speakers, for proper horn loading rather than the short conical expansion that's currently there. Whittling to be done.
Chris
That's a thought.
A quick look on eBay shows I could get a pair of aluminium plates for £10. I don't think I'd be able to cut the central hole nicely, though - the exit angle needs to be exact.
Looks like I'm staying with the 2" exit for now, though - if I go modular, P.Audio sells a decent-looking 90x40 2" horn. I'd make sure that horn could be swapped with the EV one for long rooms.
I've been hacking away at one of these horns. Looks like I could use some plumber's putty or similar to get a nice smooth transition through the woofer. Hopefully that'll clear up the CD response somewhat.
I'll be starting by THAM15 builds in Summer - haven't quite decided on how much to modify the design by, if at all.
Chris
A quick look on eBay shows I could get a pair of aluminium plates for £10. I don't think I'd be able to cut the central hole nicely, though - the exit angle needs to be exact.
Looks like I'm staying with the 2" exit for now, though - if I go modular, P.Audio sells a decent-looking 90x40 2" horn. I'd make sure that horn could be swapped with the EV one for long rooms.
I've been hacking away at one of these horns. Looks like I could use some plumber's putty or similar to get a nice smooth transition through the woofer. Hopefully that'll clear up the CD response somewhat.
I'll be starting by THAM15 builds in Summer - haven't quite decided on how much to modify the design by, if at all.
Chris
I'd love to, though EV parts are incredibly rare over here - I only got these DH1As because I did some work and got some Deltamax cabs and replaced the diaphrams myself.
Now I'm torn between THAM15s and some teeny tiny ported boxes:
Q15 Compact 15" Bass bin - Speakerplans.com Forums - Page 1
THAM15s will have way more output, but the ported boxes are much easier to move around and can be scaled for different-sized gigs.
Chris
Now I'm torn between THAM15s and some teeny tiny ported boxes:
Q15 Compact 15" Bass bin - Speakerplans.com Forums - Page 1
THAM15s will have way more output, but the ported boxes are much easier to move around and can be scaled for different-sized gigs.
Chris
Finally got the mid-highs sorted.
I've ordered a pair of Fane Sovereign Pro 12-500 midbass drivers, and a pair of P.Audio 90x40 horns.
The Fanes will be going in some Tannoy i12 cabinets (got them cheap), with the compression drivers placed on top (and then bolted down). The Tannoy cabs might need some playing with the port tuning and EQ, but I'm confident I can get something good there.
I'll make two of the ports blockable, so I can drop the tuning down to ~60Hz and EQ the bass up for smaller gigs. The Fanes are 500w rated and have 6mm Xmax, so they'll do just fine. For bigger gigs, port tuning will be ~90Hz, and then EQ the peak down to get them flat, which means they'll have loads of power handling towards the cutoff.
Once everything has arrived, I'll be getting out the measurement mic and will post results.
The Deltamax cabinets will probably end up on eBay. They've not been kind to my speaker stands - I can't get them on stands by myself, but the above modular system ought to be nice and easy.
Chris
I've ordered a pair of Fane Sovereign Pro 12-500 midbass drivers, and a pair of P.Audio 90x40 horns.
The Fanes will be going in some Tannoy i12 cabinets (got them cheap), with the compression drivers placed on top (and then bolted down). The Tannoy cabs might need some playing with the port tuning and EQ, but I'm confident I can get something good there.
I'll make two of the ports blockable, so I can drop the tuning down to ~60Hz and EQ the bass up for smaller gigs. The Fanes are 500w rated and have 6mm Xmax, so they'll do just fine. For bigger gigs, port tuning will be ~90Hz, and then EQ the peak down to get them flat, which means they'll have loads of power handling towards the cutoff.
Once everything has arrived, I'll be getting out the measurement mic and will post results.
The Deltamax cabinets will probably end up on eBay. They've not been kind to my speaker stands - I can't get them on stands by myself, but the above modular system ought to be nice and easy.
Chris
Yeah, I did quite a bit of research to land on that. Not the last word in sensitivity, but the extra couple of mm Xmax will hopefully mean they'll be more gutsy in the kick region.
Pics will go up when things arrive. For now, I need to figure out how to cover a 6000 sq.ft warehouse. Probably Deltamax cabinets (on new stands) with a thrown-together sub for more bass, plus the afore-mentioned 12" coaxials on the old stands. Both boxes are 60 degree coverage, so I'll use the Deltamaxes toed inwards a little, and the coaxials will be outer fill.
Messy, but I think we'll be firing across the room, so I suspect that's the best I'll get for now.
Shame the new Tannoy cabs won't be here earlier....
Chris
Pics will go up when things arrive. For now, I need to figure out how to cover a 6000 sq.ft warehouse. Probably Deltamax cabinets (on new stands) with a thrown-together sub for more bass, plus the afore-mentioned 12" coaxials on the old stands. Both boxes are 60 degree coverage, so I'll use the Deltamaxes toed inwards a little, and the coaxials will be outer fill.
Messy, but I think we'll be firing across the room, so I suspect that's the best I'll get for now.
Shame the new Tannoy cabs won't be here earlier....
Chris
The new drivers arrived. Pics below.
The P.Audio horns are very shallow, so I'm worried about diffraction effects as the horn's mouth angle doesn't match up to the DH1a's exit angle at all.
Time (and measurements) will tell, I suppose. If they don't work too well together, I can stick the horns on eBay and not lose much.
The Fanes are very nice, with one caveat: the foam gasket on one of them has been rotated, so all the mounting holes are blocked. I'll cut through that with a scalpel or something, as I don't like messing around with returns for something so minor.
The screws on the magnet are unrelated.
Chris
The P.Audio horns are very shallow, so I'm worried about diffraction effects as the horn's mouth angle doesn't match up to the DH1a's exit angle at all.
Time (and measurements) will tell, I suppose. If they don't work too well together, I can stick the horns on eBay and not lose much.
The Fanes are very nice, with one caveat: the foam gasket on one of them has been rotated, so all the mounting holes are blocked. I'll cut through that with a scalpel or something, as I don't like messing around with returns for something so minor.
The screws on the magnet are unrelated.
Chris
A quick test in some Tannoy T12 cabinets (like the i12, but with tophats, handles etc) indicates they're pretty smooth into the kHz region, by listening to vocal tracks etc. There's a peak there somewhere, so I'll crack out the measurement mic and see what's happening.
They're on a low-frequency break-in atm: 10Hz free air with them wired out-of-phase. Pushing a couple of mm each way excursion.
Turns out the seller had removed the SpeakOn plate from these Tannoy cabs, so I'll be putting some new ones in. There'll be 1+/- and 2+/- in, and pass-through since the compression drivers will be attached on top, with their own NL4 inputs.
M5 T-nuts and bolts are on their way to permanently install these drivers in these cabinets.
I'll use the Deltamax cabinets as temporary subs (HF horn blocked off) and see how it goes. I would rather have a bigger number of smaller subs, though.
The above was taken last night. You can just about see my PA there. The other band (which had a drum kit) was planning on using a pair of the EV plastic 12" tops, so I let them use mine instead. On an unrelated note, I need to figure out why one side of my NU6000DSP kept dropping. Wasn't going into protect, just didn't want to play.
Chris
They're on a low-frequency break-in atm: 10Hz free air with them wired out-of-phase. Pushing a couple of mm each way excursion.
Turns out the seller had removed the SpeakOn plate from these Tannoy cabs, so I'll be putting some new ones in. There'll be 1+/- and 2+/- in, and pass-through since the compression drivers will be attached on top, with their own NL4 inputs.
M5 T-nuts and bolts are on their way to permanently install these drivers in these cabinets.
I'll use the Deltamax cabinets as temporary subs (HF horn blocked off) and see how it goes. I would rather have a bigger number of smaller subs, though.
An externally hosted image should be here but it was not working when we last tested it.
The above was taken last night. You can just about see my PA there. The other band (which had a drum kit) was planning on using a pair of the EV plastic 12" tops, so I let them use mine instead. On an unrelated note, I need to figure out why one side of my NU6000DSP kept dropping. Wasn't going into protect, just didn't want to play.
Chris
Putting the NU6000 on a pair of JBL GTO1214s (wired in series on one channel) didn't teach me much - worked perfectly.
I've ordered some of the metal speakOn connectors to go from the Tannoy cabs up to the tweeters. I wanted them to be metal so I could keep track of which cable is which.
I have also e-mailed Fane to see what they say about the mounting hole issue. I've drilled the foam through now (no warranty for me!), so the drivers can be mounted once the T-nuts etc arrive, which should be later this week.
Meanwhile, here's a hint of things to come.
Edit - next I need to come up with some framework to attach the CD & horn to, and bolt to the Tannoy cabs (will be using flying points for this - should be plenty of staying power).
Chris
I've ordered some of the metal speakOn connectors to go from the Tannoy cabs up to the tweeters. I wanted them to be metal so I could keep track of which cable is which.
I have also e-mailed Fane to see what they say about the mounting hole issue. I've drilled the foam through now (no warranty for me!), so the drivers can be mounted once the T-nuts etc arrive, which should be later this week.
Meanwhile, here's a hint of things to come.
An externally hosted image should be here but it was not working when we last tested it.
Edit - next I need to come up with some framework to attach the CD & horn to, and bolt to the Tannoy cabs (will be using flying points for this - should be plenty of staying power).
Chris
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Threw one of the 12"s in a spare box (~30L ported tuned to ~80Hz), and sat the DH1a on top mounted to one of the P.Audio horns. LR4 crossover around 800Hz. No EQ, no highpass for the midbass.
These horns don't have the gain of the HP64s in the 1-5kHz range, so this is pretty damn listenable, even in mono. I think both drivers need some EQ work, though I'll reserve judgement on the midbass until its in a proper cabinet - chipboard (aka particleboard, for you Americans reading this) isn't known for its acoustical properties.
There's a lot of that midbass "slam" that people keep going on about (looks like a 3dB rise around 120Hz to me...), though I'm only a few metres from the speakers. Outdoor testing with real power will reveal a lot, I suspect.
+6dB @16kHz with a 1.5octave width has got the top end back for the EVs. This just keeps getting better!
Can't wait for the T-nuts to arrive so I can get a stereo pair up and running.
Chris
These horns don't have the gain of the HP64s in the 1-5kHz range, so this is pretty damn listenable, even in mono. I think both drivers need some EQ work, though I'll reserve judgement on the midbass until its in a proper cabinet - chipboard (aka particleboard, for you Americans reading this) isn't known for its acoustical properties.
There's a lot of that midbass "slam" that people keep going on about (looks like a 3dB rise around 120Hz to me...), though I'm only a few metres from the speakers. Outdoor testing with real power will reveal a lot, I suspect.
+6dB @16kHz with a 1.5octave width has got the top end back for the EVs. This just keeps getting better!
Can't wait for the T-nuts to arrive so I can get a stereo pair up and running.
Chris
Hmmmmm...
It turns out that the hole where the SpeakOn plate goes actually tunes the cabinet to ~87Hz, giving a huge midbass bump, which I wanted - 2nd order high-pass filter at 130Hz gives a -3dB point around 95Hz, if WinISD is to be believed.
I had planned on filling that hole in with a piece of plywood (with SpeakOns), and modifying the existing ports for a higher tuning. With this development, though, I'm not so sure...
Option A:
- drill the cabinet for SpeakOn terminals (needs routering to sink them)
- use the existing cutout for bass reflex tuning
Option B:
- cover the existing cutout, and put the SpeakOn terminals there.
- add new bass port somehow.
Leaning toward option A, though it might be worth covering the port with fabric - its a 5"x3" rectangle.
Chris
It turns out that the hole where the SpeakOn plate goes actually tunes the cabinet to ~87Hz, giving a huge midbass bump, which I wanted - 2nd order high-pass filter at 130Hz gives a -3dB point around 95Hz, if WinISD is to be believed.
I had planned on filling that hole in with a piece of plywood (with SpeakOns), and modifying the existing ports for a higher tuning. With this development, though, I'm not so sure...
Option A:
- drill the cabinet for SpeakOn terminals (needs routering to sink them)
- use the existing cutout for bass reflex tuning
Option B:
- cover the existing cutout, and put the SpeakOn terminals there.
- add new bass port somehow.
Leaning toward option A, though it might be worth covering the port with fabric - its a 5"x3" rectangle.
Chris
Agreed, though I'll need to brush up on my routering skills before I attack the cabinets.
IIRC, the big hole in the back will "short out" the front-firing bass ports, so I shouldn't need to do anything with them. Impedance sweeps will tell all, methinks.
The front ports are tuned around 50Hz, meaning I can apply boost down there and get to 50Hz if the back port is blocked off somehow. Very useful for smaller gigs - no need to bring subs then.
I'm part-way through designing a stand for the DH1a & horn. Looks like it'll take some work to get it nice, but I'm aiming for a hinged bit at the front, with the option to prop up the compression driver a little, angling the horns downwards - no point in annihilating the ceiling with treble. I'm using SketchUp for this, so there might be some pretty pictures soon.
A further difficulty is that I'll be using different HF horns for different rooms - got 2x EV HP64 and 2x P.Audio 942s, one of which is twice as deep as the other.
Chris
IIRC, the big hole in the back will "short out" the front-firing bass ports, so I shouldn't need to do anything with them. Impedance sweeps will tell all, methinks.
The front ports are tuned around 50Hz, meaning I can apply boost down there and get to 50Hz if the back port is blocked off somehow. Very useful for smaller gigs - no need to bring subs then.
I'm part-way through designing a stand for the DH1a & horn. Looks like it'll take some work to get it nice, but I'm aiming for a hinged bit at the front, with the option to prop up the compression driver a little, angling the horns downwards - no point in annihilating the ceiling with treble. I'm using SketchUp for this, so there might be some pretty pictures soon.
A further difficulty is that I'll be using different HF horns for different rooms - got 2x EV HP64 and 2x P.Audio 942s, one of which is twice as deep as the other.
Chris
Plan A has gone ahead, and some SpeakOn holes have been cut into the cabinet.
There's a few screwholes where the old Tannoy crossover used to screw into the cabinets, so I've put T-nuts in there so I can bolt a plate over when the subs aren't being used.
The top-plate for the compression driver is coming along, too. Need to test-fit the P.Audio horns and play with angling them down slightly. They bolt into the existing flying holes nicely, though, so I'm quite pleased. Not long until I can have a proper listen.
I've also ordered some 1" horns for the Das M3 compression drivers I've got lying around. The horns have variable-width dispersion, so I'll have them taper towards the top of the vertical coverage, providing a wide dispersion near the stage. Very cheap if I don't get on with them.
Chris
There's a few screwholes where the old Tannoy crossover used to screw into the cabinets, so I've put T-nuts in there so I can bolt a plate over when the subs aren't being used.
The top-plate for the compression driver is coming along, too. Need to test-fit the P.Audio horns and play with angling them down slightly. They bolt into the existing flying holes nicely, though, so I'm quite pleased. Not long until I can have a proper listen.
I've also ordered some 1" horns for the Das M3 compression drivers I've got lying around. The horns have variable-width dispersion, so I'll have them taper towards the top of the vertical coverage, providing a wide dispersion near the stage. Very cheap if I don't get on with them.
Chris
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