I got to do some cone-slicing again 🙂
Working on a 3-way (inspired by Troels PMS) and re-used some Vifa M13 mids. I wanted to do a 1st order (electrical) LP on the mid to get good phase tracking with the tweeter, but it had some breakup peaks from 7k and up that worried me.
4 slices per cone, and everything looked a lot better. Peaks were down abt 5dB.
This time I applied most of the glue from the back of the cone, and just added a little bit from the front of the cone dipping a resistor leg in the glue and using that to apply small amounts of glue to the front of the cone. Looked cleaner, and seems to work just as well. Now I just added a RC in parallel to the LP coil to slightly tame it further.
Sorry, no pictures or measurements to post, but maybe I could add a picture of the modified driver later. Nice to finally be able to see the benefit of it in an actual project.
Working on a 3-way (inspired by Troels PMS) and re-used some Vifa M13 mids. I wanted to do a 1st order (electrical) LP on the mid to get good phase tracking with the tweeter, but it had some breakup peaks from 7k and up that worried me.
4 slices per cone, and everything looked a lot better. Peaks were down abt 5dB.
This time I applied most of the glue from the back of the cone, and just added a little bit from the front of the cone dipping a resistor leg in the glue and using that to apply small amounts of glue to the front of the cone. Looked cleaner, and seems to work just as well. Now I just added a RC in parallel to the LP coil to slightly tame it further.
Sorry, no pictures or measurements to post, but maybe I could add a picture of the modified driver later. Nice to finally be able to see the benefit of it in an actual project.
Wouldn't it be less nerve wracking to simply goop lines of silicon, or glue strips of a stiff material onto the cone? I vaguely recall there being a thread about this eons ago, might be worth a search
That is likely not going to work: as far as I understand, the slits interrupt the travelling waves in the cone, and thus should be gaps/open. The glue (or whatever filler) is primarily there to assure airtightness, and only secundarily as stiffner.
I would love to see some simulations of solid cone behaviour vs the same cone slitted.
I would love to see some simulations of solid cone behaviour vs the same cone slitted.
I did it on a pair of SB13PFC's (I think it was). Breakup improved, but there was still some left. I added some coating too, and that improved it a little bit more. The speakers I built with them sounded pretty ok. Used them as front speakers for my surround system for a while, and now they are mostly collecting dust.. 🙂
I actually found some pictures from the mod. FR before and after slicing, and how I sliced it. From memory dustcap did very little. Measured in baffle of the speaker, so it's a bit rough, but you can see the diff.
This is before coating though. I put some coating all the way to the inner fold of the surround. (Troels style, and as some manufacturers do). That smoothed out the dip under 2k a bit, I guess that was related to the surround.
This is before coating though. I put some coating all the way to the inner fold of the surround. (Troels style, and as some manufacturers do). That smoothed out the dip under 2k a bit, I guess that was related to the surround.
I have fallen back into the cone slicing addiction 🙂
I could not resist a set of cheap speakers used in a surround system for abt 15Eur sold locally, so I picked them up after work and thought I would see if they could be used for something.
Fronts were some chinese made 'Cross Wood'-branded 3-ways with 2x10" woofers, 5" mid and a 1" dome tweeter. Still have a pair of small Tangent EVO's used as rear speakers that I might tackle, those have alu cone midwoofers that also have a nasty untamed peak.
First thing I could hear when connecting these was boomy bass and strong treble. The bass was fixed with bracing and damping the box, some extra magnets on the woofers, and it sounded pretty ok after.
Found out the pronounced treble was from a resonance in the mid and a rising FR. XO is 1st order on all except tweeter that has 2nd order, so well behaved drivers should be used.. The mid had a nasty peak around 5-6kHz, and a complete new XO is out of the question considering price range of the speakers, so I wanted to improve the the mids FR.
I was not been able to pinpoint the source of the resonance for sure (was a bit hasty to get them done though). I removed the dust-cap, and no real change to the peak so it was glued back. I put PVA glue on the rear of the cone, no change, -slit the cone and tried epoxy to glue the slits (not a good choice), put Modpodge on the front of the cone, small improvement, put it on the rear of the cone too, small improvement again, added another layer on the front of the cone, even better, but one was slightly worse, so I added another thin layer on the front of the cone on that one. Left that to dry last night, and will re-check this evening, but I think they should be ok to use, at least a lot better than before. Mids had a lot of extension (close to 10k from memory), and there was too much overlap in the mid/tweeter XO region, so I figure some extra weight addded will give it some earlier roll off too. Some padding on the tweeter, and these might be good enough to use in the garage for background music.
I already spent way too much time on them, but that's the hobby I guess. I guess it's a 'slow and dirty' mod.
BTW I built a pair of speakers from the above SBA drivers, using them in the kitchen, and still happy with the sound.
Picture of modpodge drying after first application:
I could not resist a set of cheap speakers used in a surround system for abt 15Eur sold locally, so I picked them up after work and thought I would see if they could be used for something.
Fronts were some chinese made 'Cross Wood'-branded 3-ways with 2x10" woofers, 5" mid and a 1" dome tweeter. Still have a pair of small Tangent EVO's used as rear speakers that I might tackle, those have alu cone midwoofers that also have a nasty untamed peak.
First thing I could hear when connecting these was boomy bass and strong treble. The bass was fixed with bracing and damping the box, some extra magnets on the woofers, and it sounded pretty ok after.
Found out the pronounced treble was from a resonance in the mid and a rising FR. XO is 1st order on all except tweeter that has 2nd order, so well behaved drivers should be used.. The mid had a nasty peak around 5-6kHz, and a complete new XO is out of the question considering price range of the speakers, so I wanted to improve the the mids FR.
I was not been able to pinpoint the source of the resonance for sure (was a bit hasty to get them done though). I removed the dust-cap, and no real change to the peak so it was glued back. I put PVA glue on the rear of the cone, no change, -slit the cone and tried epoxy to glue the slits (not a good choice), put Modpodge on the front of the cone, small improvement, put it on the rear of the cone too, small improvement again, added another layer on the front of the cone, even better, but one was slightly worse, so I added another thin layer on the front of the cone on that one. Left that to dry last night, and will re-check this evening, but I think they should be ok to use, at least a lot better than before. Mids had a lot of extension (close to 10k from memory), and there was too much overlap in the mid/tweeter XO region, so I figure some extra weight addded will give it some earlier roll off too. Some padding on the tweeter, and these might be good enough to use in the garage for background music.
I already spent way too much time on them, but that's the hobby I guess. I guess it's a 'slow and dirty' mod.
BTW I built a pair of speakers from the above SBA drivers, using them in the kitchen, and still happy with the sound.
Picture of modpodge drying after first application:
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What drivers are you using in the image?
Doesn't the weight increase quite a lot with modpodge?
How many layers should you put on?
The driver is some cheap chinese s***t from the mentioned speaker. I thought I put enough after three layers, one on the rear and two on the front, but below is the approximate FR before and after, so not much return for the invested time. It was looking better yesterday before it was completely dry, but now the peak is partially back. I will leave it like that and see if I can make it listenable or just scrap it. It is pretty decent off axis though.
