Hi Everyone. A quick intro and a question for you. I am a relative newbie to speaker building. I have completed a bass guitar cabinet using a single JBL 2245H that turned out pretty good. This in turn has given me a pretty big itch to complete a project a little more adventurous. I've got a decent wood shop so I'm combining two of my favorite interests, music & woodworking. This forum seems like a great resource! OK, at any rate here's the deal:
Latest project- build (5) two-way speakers for hometheater surrounds. Woofers will be the Focal 6W4311, already purchased. Boxes 3/4" MDF and vented. BBPro used to get the optimal Vb. My choice for the tweeter is either the Morel MDT-20 or MDT-30. I was hoping to get opinions on which to use (excepting the obvious cost difference). OR, even opinions on an altogether different one. Any other tips greatly appreciated too!
Thanks,
jchappj
Latest project- build (5) two-way speakers for hometheater surrounds. Woofers will be the Focal 6W4311, already purchased. Boxes 3/4" MDF and vented. BBPro used to get the optimal Vb. My choice for the tweeter is either the Morel MDT-20 or MDT-30. I was hoping to get opinions on which to use (excepting the obvious cost difference). OR, even opinions on an altogether different one. Any other tips greatly appreciated too!
Thanks,
jchappj
Re: tweeter advice
1). They will be the surrounds for a 6.1 system. I'm using a pair of Polk Monitor 5's for the Center.
2). They're unshielded. Here's the MDT-30, and here's the MDT-20. Here's the Focal spec's.
3). The crossover is my next step, I haven't gotten that far yet. The woofer range is 50 Htz-4500kHtz. The tweeters are 1300 and 1600 - 20,000kHtz. I'm using a subwoofer on the system, 150 Htz crossover point for the really deep bass.
1). They will be the surrounds for a 6.1 system. I'm using a pair of Polk Monitor 5's for the Center.
2). They're unshielded. Here's the MDT-30, and here's the MDT-20. Here's the Focal spec's.
3). The crossover is my next step, I haven't gotten that far yet. The woofer range is 50 Htz-4500kHtz. The tweeters are 1300 and 1600 - 20,000kHtz. I'm using a subwoofer on the system, 150 Htz crossover point for the really deep bass.
I used the similar Focal 6w4252 in this speaker Link. The woofer has a slightly bigger peak at 4500 Hz. Crossed over 4th order LR at 2400 Hz I still felt like I needed a notch filter to smooth it out. Keep that in mind if you try it without a notch at first. Crossing over lower will probably eliminate the need for the notch.
I don't have any experience with the Morels so I won't comment there. I am very happy with the Focal T120DX5 I used. They are more expensive than the Morel's though. At any rate, the 6W4311 should do quite well up to at least 2500 Hz, giving you flexibility in choosing a crossover point. As surrounds these speakers might convince you to upgrade your mains.
I like the sound of my bass played through a 2245H, too. It's my music system subwoofer driven by a bridged Hafler DH-500, so I don't do it often. The first time I was enjoying it so much that my then 15 year old, loud hip hop loving daughter reminded me that "We have neighbors, you know."
I don't have any experience with the Morels so I won't comment there. I am very happy with the Focal T120DX5 I used. They are more expensive than the Morel's though. At any rate, the 6W4311 should do quite well up to at least 2500 Hz, giving you flexibility in choosing a crossover point. As surrounds these speakers might convince you to upgrade your mains.
I like the sound of my bass played through a 2245H, too. It's my music system subwoofer driven by a bridged Hafler DH-500, so I don't do it often. The first time I was enjoying it so much that my then 15 year old, loud hip hop loving daughter reminded me that "We have neighbors, you know."
Using X-Over Pro I came up with the attached graph for my proposed crossover network. I got the theoretical values from the program then replaced them with values that are close but easily purchasable. I would appreciate opinions as it looks pretty good to me but being new to this I'm not sure. Is there any way to smooth out that ~3dB drop? Thank you. I ended up with Morel MDT-37's BTW...
jchappj
jchappj
Attachments
Thank you Timn8ter.
Gasho said:
Interesting. Given the choice of tweeter, what would you recommend for the other driver? And pardon once again my ignorance, but I have tried my best to research this. My postings on the forum didn't yield a whole lot so I plowed on ahead. Where would one go to find these 'driver qualities'? Can you discern this from their spec sheet? I am definately on a learnig curve so thanks for the help.
The MDT37 should actually work fine with the focal. It's a good tweeter I'm very familiar with. I've not used that particular woofer, but have used a number of Focals including a W cone model.
AFA the crossover: if only it were that easy. I don't want to damp your beginner's enthusiasm, but there are some significant factors you're overlooking. First, the impedance of the drivers is not a flat 8 ohm resistive load, so the actual measured crossover response will not look anything like the graph you posted. Second, you haven't compensated for the baffle step, which means the lower midrange and midbass will be weak. Third, the tweeter will need to be padded down significantly; I guarantee it.
To make the crossover work as is, you would need to add a zobel network to the woofer, as well as a baffle compensation network. The tweeter will need as a minimum a series notch type impedance compensation, and an L-pad attenuator.
Experienced crossover designers generally try to combine some of these elements to keep the parts count down. For instance, just use a larger than low pass coil on the woofer for starters. Think more like 1.5mH.
At at minimum, you'll need a radio shack SPL meter and test CD or signal generator for testing. It's really best to have one of these computer programs that measure the drivers and optimize the crossover to fit reality.
For a crossover that will work with those drivers with minimal measuring gear and mental stress, I'd recommend you take a look at the 'acoustic-reality' series crossover. (google!) I think the publisher may post at this forum.
GB
AFA the crossover: if only it were that easy. I don't want to damp your beginner's enthusiasm, but there are some significant factors you're overlooking. First, the impedance of the drivers is not a flat 8 ohm resistive load, so the actual measured crossover response will not look anything like the graph you posted. Second, you haven't compensated for the baffle step, which means the lower midrange and midbass will be weak. Third, the tweeter will need to be padded down significantly; I guarantee it.
To make the crossover work as is, you would need to add a zobel network to the woofer, as well as a baffle compensation network. The tweeter will need as a minimum a series notch type impedance compensation, and an L-pad attenuator.
Experienced crossover designers generally try to combine some of these elements to keep the parts count down. For instance, just use a larger than low pass coil on the woofer for starters. Think more like 1.5mH.
At at minimum, you'll need a radio shack SPL meter and test CD or signal generator for testing. It's really best to have one of these computer programs that measure the drivers and optimize the crossover to fit reality.
For a crossover that will work with those drivers with minimal measuring gear and mental stress, I'd recommend you take a look at the 'acoustic-reality' series crossover. (google!) I think the publisher may post at this forum.
GB
Wow, thanks Greg B! Everything that I had read tended to shift me toward a parallel crossover. This is really interesting, and will give me some more 'hands on' study as I continue. As far as the network mentioned here and your comments, don't worry about dampening my enthusiasm. For me making a mistake is a learning tool. In fact, any other insights would be greatly appreciated. Thanks once again.
You're welcome. Caught me at the right time - when I felt like typing, and I've used similar combos.
Parallel and series xover types both have their advantages. I prefer parallel maybe 2/3 of the time; other times series is -clearly- superior. Series has the advantage of sounding good even if it's a little off. It depends on the situation. It's been my experience that the MDT37 is a good driver for a series type, very tough. I do like the AR type with a some R on the shunt leg. Keeps the impedance stable.
For purposes of learning, you might consider buying a bunch of cheap sale chokes, resistors and caps from madisound or wherever to fiddle around with. Just experiment and hear for yourself. Start with just a 4.7uf cap on the tweeter and 2.2mH choke for a lowpass, and see what happens....
gb
Caught me at the right time - when I felt like typing, and I've used similar combos.Parallel and series xover types both have their advantages. I prefer parallel maybe 2/3 of the time; other times series is -clearly- superior. Series has the advantage of sounding good even if it's a little off. It depends on the situation. It's been my experience that the MDT37 is a good driver for a series type, very tough. I do like the AR type with a some R on the shunt leg. Keeps the impedance stable.
For purposes of learning, you might consider buying a bunch of cheap sale chokes, resistors and caps from madisound or wherever to fiddle around with. Just experiment and hear for yourself. Start with just a 4.7uf cap on the tweeter and 2.2mH choke for a lowpass, and see what happens....
gb
?? Perhaps 0.68mH is closer to right value???Nope. It always takes a bigger inductor than you'd think. Between the baffle step and the woofer's rising inductance, a .68mH will do little except take a couple db's off the breakup peak.
Anyway, this wasn't really a suggested crossover. Just something that will 'work' enough to hear what the drivers sound like.
OTOH, it's possible it could get OK results if used in conjunction with a notch filter on the woofer to deal with the breakup, and series notch on the tweeter to fix the impedance hump at Fs.
Here's a 4th order (acoustic) crossover using that woofer: murphyblaster 2way
GB
Anyway, this wasn't really a suggested crossover. Just something that will 'work' enough to hear what the drivers sound like.
OTOH, it's possible it could get OK results if used in conjunction with a notch filter on the woofer to deal with the breakup, and series notch on the tweeter to fix the impedance hump at Fs.
Here's a 4th order (acoustic) crossover using that woofer: murphyblaster 2way
GB
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