I agree. With a that high Qts the Rm would expected to be much higher too. I didn't continue beyond the point of the math I've posted though, I wanted some confirmation first because I was more interested in finding the cause of the error than in finding the actual values.
I would try to increase Rs (x10 ~ x50) and increase the Vs a bit too, if you'd chose a very high Rs. That way you get less influence of the testing equipment, probe wires (horrible: crocodile wires!
) etc.
I'm going to use those 5" drivers for midrange from 350 Hz - 3 kHz. I have a 6.5" I'll use to reinforce the bass, and then I've got quite a nice 6.5" for the bass extension. This is not intended to be equivalent of $1000 speakers or anything. The TS parameters I've measured using these deviations from the equations I was using seem to fit the drivers I know the TS parameters of, so that's a good start.
I'm doing something I've never done - the speakers are going to stand 1.35 m tall, and they're about 21 cm wide and 30 cm deep. I'm making 3 chambers. Using a very loose approximation, the results look better than I expected in Boxsim. Let's see what happens.
I'm doing something I've never done - the speakers are going to stand 1.35 m tall, and they're about 21 cm wide and 30 cm deep. I'm making 3 chambers. Using a very loose approximation, the results look better than I expected in Boxsim. Let's see what happens.
Just please note, these old 5" drivers are not what one would call high quality, so spending such a huge amount of time on them isn't worth it. I'm still not going to get fantastic results out of them. If I want to change their characteristics, I'm going to really have to get involved in the electronics, and this is much more expensive than paying nothing for what I've already got.
Ah, well, if you're using them with a that high lower crossover, the tsp doesn't matter that much because that's far, far above the fs.
That's a pretty bad idea, you'll have to invest a lot of time to get these 2 bass drivers matching in phase. Besides that, one of the 6,5" won't give you any more dynamic, it's still limited by the excursion of the lower one.
I'm doing something I've never done - the speakers are going to stand 1.35 m tall, and they're about 21 cm wide and 30 cm deep. I'm making 3 chambers. Using a very loose approximation, the results look better than I expected in Boxsim. Let's see what happens.
If you want to do it passive, you'll invest a ton more on coils than on all your speakers if you want to cross over that low (6,5"-6,5"). Calculate first how much the coils are going to cost you! You most likely have to flatten the impedance/resonance too (on both 6,5") to make the crossover work.
They aren't bad or at least thery weren't bad once. See, they have air dried membranes and dustcaps (the crumpling on it gives it away), that is a LOT more expensive and more sturdy than cheap pressed paper. And the size of the magnet costs a lot too, at least if it's not just an empty tin box.
I would really suggest to go only 3 way instead of 4, you save a ton of money and extremely likely sound much better. Cheap or even medium priced big coils have a high resistance, which pushes the Qts up and you get a more boomy and less precise bass.
And the most important thing: You're doing the search for the error not for this box, you're doing it for all comming projects.
That's plain wrong. You can get a DSP for less than 200€, some even less. The big coils you'd need will easily exeed that.
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You are absolutely correct. Just a few notes on what you've said below, but yes, you make 100% valid points, and I can't argue any.
I was hoping to use them for bass/mid, but this is the exact reason I'm using them for mid. And I have the two 6.5"'s as well.
The very simple crossover I designed doesn't look too bad. I might even have enough enamel wire lying around. I think I need one big inductor and two small ones per crossover. I'm going to use ferrite cores.
Well, the ones in the photo are new, and are the nice (and cheap) 6.5" drivers I bought to try out. Coincidentally, the 5" ones are old, and a bit dried out, but we'll see how they do.
I am - I'm putting the 6.5" drivers in parallel. My overall impedance is going to be 4 ohms. The theoretical impedance curve is very easy to drive.
Yes, absolutely. I will continue with that. But I've found a set of equations that seem to work. I measured the W170S's with my updated method (according to what I've learned in this thread), and the result is much closer to the claimed specs.
I'd rather not do the DSP. It's not my thing. I did an entire project on DSP where the unit measured the in-room frequency response and calculated a filter to correct the frequency response. The aim was to reduce resonances, and the unit worked very well, but this isn't the route I want to follow.
That's not to say DSP isn't a good thing. But where do I stop? I'm completely obsessed with getting my imaging right, getting my frequency response right. I end up not enjoying my music because I listen so hard to the speakers. I think my head has been in every conceivable position in my living room trying to find the bass nodes, or best listening position. To me, if the speakers sound good, I'll use them. If not, they gather dust in the cupboard until another day when I try again. It's a hobby, and I want to enjoy it. If I introduce DSP, I'll never be satisfied.
I was hoping to use them for bass/mid, but this is the exact reason I'm using them for mid. And I have the two 6.5"'s as well.
The very simple crossover I designed doesn't look too bad. I might even have enough enamel wire lying around. I think I need one big inductor and two small ones per crossover. I'm going to use ferrite cores.
Well, the ones in the photo are new, and are the nice (and cheap) 6.5" drivers I bought to try out.
Coincidentally, the 5" ones are old, and a bit dried out, but we'll see how they do.I am - I'm putting the 6.5" drivers in parallel. My overall impedance is going to be 4 ohms. The theoretical impedance curve is very easy to drive.
Yes, absolutely. I will continue with that. But I've found a set of equations that seem to work. I measured the W170S's with my updated method (according to what I've learned in this thread), and the result is much closer to the claimed specs.
I'd rather not do the DSP. It's not my thing. I did an entire project on DSP where the unit measured the in-room frequency response and calculated a filter to correct the frequency response. The aim was to reduce resonances, and the unit worked very well, but this isn't the route I want to follow.
That's not to say DSP isn't a good thing. But where do I stop? I'm completely obsessed with getting my imaging right, getting my frequency response right. I end up not enjoying my music because I listen so hard to the speakers. I think my head has been in every conceivable position in my living room trying to find the bass nodes, or best listening position. To me, if the speakers sound good, I'll use them. If not, they gather dust in the cupboard until another day when I try again. It's a hobby, and I want to enjoy it.
If I introduce DSP, I'll never be satisfied.Now I know this isn't anywhere near perfect, but I'm doing it for the fun, and hopefully I can get something usable out of these drivers I have lying around.
The speaker box layout is as shown, and I'm going to pack fiberglass into the enclosures tightly. I have a whole lot lying around, and I want to use it. Horrible stuff it is though. I'll try put it into some sort of material like an old lace curtain to keep the fibres to themselves.
The crossover is something like shown. I don't have the exact values on this computer, but I think it's close enough to what I came to.
I'm also doing this because I had excess wood from another project (that's the one I've really spent time and money on).
The speaker box layout is as shown, and I'm going to pack fiberglass into the enclosures tightly. I have a whole lot lying around, and I want to use it. Horrible stuff it is though. I'll try put it into some sort of material like an old lace curtain to keep the fibres to themselves.
The crossover is something like shown. I don't have the exact values on this computer, but I think it's close enough to what I came to.
I'm also doing this because I had excess wood from another project (that's the one I've really spent time and money on).
Attachments
Are that resistors in series to the woofers? If it is, that will skyrocket your Qts! Why!?
Your lowpass will not be sufficient to compensate for the response increase, at 6dB you'll need to increase the coil to at least 2x the value.
The woofers are way too far apart, that works for subwoofers but not for woofers, you'll get interferences vertically. Two different port frequencies will do the same since the ports have a massive phase shift within a very small frequency range. And the less capable driver will always limit the system.
If it is, that will skyrocket your Qts! Why!?Your lowpass will not be sufficient to compensate for the response increase, at 6dB you'll need to increase the coil to at least 2x the value.
The woofers are way too far apart, that works for subwoofers but not for woofers, you'll get interferences vertically. Two different port frequencies will do the same since the ports have a massive phase shift within a very small frequency range. And the less capable driver will always limit the system.
Goodness, no, the resistors are to model the Re.
Thanks for that - I am in full agreement. They don't measure too far apart, and they will both handle the same power and have the same excursion (theoretically). They're about 100W drivers each (not nominal - I would put up to 50 W nominal into each). I'll see how they work out in terms of phase when I've built them - I can always disconnect the bottom one (that's how I've planned it).
Now, I don't expect miracles with this one. But I want to hear it, and then if it's worth it, I'll tweak it in the future. The way it's laid out, I can move the tweeter to the bottom and flip the whole thing upside down, change the chambers inside and keep it useable. The reason is that the 6.5" in the middle chamber is without a doubt the best option for the low frequencies. The bottom 6.5" is possibly better for midrange than the two 5"ers. The electronics can certainly start off simple, and then become nicely complex in the future (if I find it's worth it). I've literally spent time and R240 on this so far. I'm hoping to learn by building, changing, tweaking, etc. But that's the great thing about a forum like this - your responses have knowledge in them that you can't search for on Google. So I'm very grateful for the replies. Hopefully I can do the same by learning more.
Thanks for that - I am in full agreement. They don't measure too far apart, and they will both handle the same power and have the same excursion (theoretically). They're about 100W drivers each (not nominal - I would put up to 50 W nominal into each). I'll see how they work out in terms of phase when I've built them - I can always disconnect the bottom one (that's how I've planned it).
Now, I don't expect miracles with this one. But I want to hear it, and then if it's worth it, I'll tweak it in the future. The way it's laid out, I can move the tweeter to the bottom and flip the whole thing upside down, change the chambers inside and keep it useable. The reason is that the 6.5" in the middle chamber is without a doubt the best option for the low frequencies. The bottom 6.5" is possibly better for midrange than the two 5"ers. The electronics can certainly start off simple, and then become nicely complex in the future (if I find it's worth it). I've literally spent time and R240 on this so far. I'm hoping to learn by building, changing, tweaking, etc. But that's the great thing about a forum like this - your responses have knowledge in them that you can't search for on Google. So I'm very grateful for the replies. Hopefully I can do the same by learning more.
About the drivers - the guy at the shop tells me they're no-name things, and there will be no specs available. So far I'm quite happy though. Low distortion from what I can hear and compared to other speakers I've listened to. Decent Fs and Vas. The only gripe I have is with the way the surround is glued on - it's not the best work I've seen. Also, they're very cheap - I can thrash them and not really care too much (the same goes for all the speakers I've mentioned in this thread).
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