I have been looking for quite a while for a solution to the problems involved in finding a tweeter for a three way. I'll go briefly into the design goals, you can skip these if you want to just see the results so far.
I want some good deep bass without a standalone sub, so I am using 2 sealed Dayton 10HF per cabinet (I note that a real woofer opens up more options by going higher, but will not reach as low unless it has extreme surface area). I'm crossing that at about 100 Hz, to a 7" midbass, after baffle step and all, I think a 7" will do much better than a 5". I chose SS 4531G after seeing MarkK's and Zaph's distortion tests. I have been trying to find a tweeter that can match the dynamic range of the rest of the system, and match the power response. My compromise tweeter will be the Peerless HDS, but I anticipate that the BMS4540ND may do better.
Attached is a diagram of the waveguide I built. I have a quarter inch radius at the mouth entry transitioning the driver to the waveguide, I took off 1/32" off so that the radius would be tangent to the horn (see picture). For that, I used a roundover bit on the router, and then a 3/4" end mill. The rest of the horn is straight, I cut two circles in 3/4" thick wood progressively wider, and filled everything with spackle filler. The mouth transition to baffle has some 1/4" high by 1/2" wide felt around it. The measuring baffle is about 20" by 25" wide, with the horn centered in it.
Anyone have any recommendations for filler I can apply thickly that won't crack, the spackle sucks (I realize I'm supposed to apply a little at a time, but I'm impatient). Alternately, if horn lathing offers are still open, I would take one of those too.
Attached are some measurements I took. These are hasty, I stacked things on a ladder in the middle of my room, horn baffle is held over the driver by gravity because the driver has a screw adapter (I'm working something that will fasten it better, plate mount adapters from PE don't fit well for this driver). I held the microphone manually and used TrueRTA because I could take measurement quickly, I need to fasten things down better so I can use my mike stand, and get some more time to deal with properly gated SpeakerWorkshop measurements or my Matlab script. Measurements are from about 70 cm, angle is eyed. Everything is plotted in Matlab, unsmoothed 1/24 octave resolution.
Results are attached, I feel they are promising. Off axis response at 20Khz is good. I feel the equalization will not be too bad, and hopefully some of the abberations go away with a better measurement setup, maybe a wider felt band.
Unfortunately, I think I will need to put a resistor in series with it to quiet it down, its too sensitive. On my speakers the noise floor of my Adcom pre, and homemade amps is just fine, but with the compression tweeter, it is audible. Its too bad because it is a real waste of sensitivity.
I want some good deep bass without a standalone sub, so I am using 2 sealed Dayton 10HF per cabinet (I note that a real woofer opens up more options by going higher, but will not reach as low unless it has extreme surface area). I'm crossing that at about 100 Hz, to a 7" midbass, after baffle step and all, I think a 7" will do much better than a 5". I chose SS 4531G after seeing MarkK's and Zaph's distortion tests. I have been trying to find a tweeter that can match the dynamic range of the rest of the system, and match the power response. My compromise tweeter will be the Peerless HDS, but I anticipate that the BMS4540ND may do better.
Attached is a diagram of the waveguide I built. I have a quarter inch radius at the mouth entry transitioning the driver to the waveguide, I took off 1/32" off so that the radius would be tangent to the horn (see picture). For that, I used a roundover bit on the router, and then a 3/4" end mill. The rest of the horn is straight, I cut two circles in 3/4" thick wood progressively wider, and filled everything with spackle filler. The mouth transition to baffle has some 1/4" high by 1/2" wide felt around it. The measuring baffle is about 20" by 25" wide, with the horn centered in it.
Anyone have any recommendations for filler I can apply thickly that won't crack, the spackle sucks (I realize I'm supposed to apply a little at a time, but I'm impatient). Alternately, if horn lathing offers are still open, I would take one of those too.
Attached are some measurements I took. These are hasty, I stacked things on a ladder in the middle of my room, horn baffle is held over the driver by gravity because the driver has a screw adapter (I'm working something that will fasten it better, plate mount adapters from PE don't fit well for this driver). I held the microphone manually and used TrueRTA because I could take measurement quickly, I need to fasten things down better so I can use my mike stand, and get some more time to deal with properly gated SpeakerWorkshop measurements or my Matlab script. Measurements are from about 70 cm, angle is eyed. Everything is plotted in Matlab, unsmoothed 1/24 octave resolution.
Results are attached, I feel they are promising. Off axis response at 20Khz is good. I feel the equalization will not be too bad, and hopefully some of the abberations go away with a better measurement setup, maybe a wider felt band.
Unfortunately, I think I will need to put a resistor in series with it to quiet it down, its too sensitive. On my speakers the noise floor of my Adcom pre, and homemade amps is just fine, but with the compression tweeter, it is audible. Its too bad because it is a real waste of sensitivity.
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