This morning, just for the hell of it, I added a 9" x 27" x 1" foam pad inside the cabinet. Initially, I lined the inside of the cabinet with 1/4" jute carpet pad I had laying around. The additional foam really tighten up the base quite a bit and seemed to eliminate the hump in the upper bass area. I am thinking of not adding a port since I have a M&K MX70 subwoofer to fill in deep base area. I remember when I restored the Large Advents, the cabinets were filled with foam blocks.
Still playing them with the Radio Shack LX5 2-way until the new tweeters and cross overs arrive in a few days. Actually, the Linaeum tweeters don't sound half bad but the LX5 5.25" woofer just flat out doesn't cut it. Thought about replacing woofer with a better one. But that won't be necessary once the cross over and the tweeters are here.
Still playing them with the Radio Shack LX5 2-way until the new tweeters and cross overs arrive in a few days. Actually, the Linaeum tweeters don't sound half bad but the LX5 5.25" woofer just flat out doesn't cut it. Thought about replacing woofer with a better one. But that won't be necessary once the cross over and the tweeters are here.
Nice that it tightened the bass. I've read that dense foam pads can make things sound more dead than damped, and that more and looser stuffing can make things more damped than dead. I have two Kef Kube 10b subs with 1" foam like you added, and they sound nicely damped though, so maybe it's speaker dependent. I only bring it up because the person who said it is right about a lot of things
I edited my last post on page 2, so if you didn't see it, check it.
I like sealed designs, they are great. If your sub's low pass is 24db/oct, a ported design for you speaker might be better for integration though. You can plug the hole(s) to make your box sealed.
The only way to tune a sealed box is to adjust its size, so you're stuck with its tuning at this point. I think you should design it ported and plug the holes in case the size for sealed isn't optimal.
How many braces are you going to end up using, and what are their dimensions? (To subtract from the box volume for calculations)
I like sealed designs, they are great. If your sub's low pass is 24db/oct, a ported design for you speaker might be better for integration though. You can plug the hole(s) to make your box sealed.
The only way to tune a sealed box is to adjust its size, so you're stuck with its tuning at this point. I think you should design it ported and plug the holes in case the size for sealed isn't optimal.
How many braces are you going to end up using, and what are their dimensions? (To subtract from the box volume for calculations)
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The gross box calculation is 52L then I added braces around the inside perimeter and between the right and left sides. None front to back yet, so I figured it nets out to ~48L. The Dynaudio 24W100 woofer spec sheet show test with a 50L box. I haven't done the exact calculations yet.
When I ran the cabinet design on-line, the results show it can be either ported or sealed. The foam I added is only 1" thick and I put it only at the rear of the cabinet. In the Large Advents, the foam blocks pretty much filled the cabinet.
With regards to the crossover, I don't fully understand what you said...lack of knowledge...so I have to do more research. It appears that I can simply replace the caps to tweek the cross over point. Regarding the slope, its the 2nd order 12db/octave so lets see how that sounds before doing anything.
When I ran the cabinet design on-line, the results show it can be either ported or sealed. The foam I added is only 1" thick and I put it only at the rear of the cabinet. In the Large Advents, the foam blocks pretty much filled the cabinet.
With regards to the crossover, I don't fully understand what you said...lack of knowledge...so I have to do more research. It appears that I can simply replace the caps to tweek the cross over point. Regarding the slope, its the 2nd order 12db/octave so lets see how that sounds before doing anything.
I found this cross over calculator on line. Not 100% sure if I should use 8ohm or some different value for the tweeter and woofer.
Bessel 2 way 4th Order (24dB) Crossover culculator | Audio products
Bessel 2 way 4th Order (24dB) Crossover culculator | Audio products
For building speakers that's a big no-no. You have to decide what kind of speaker you want to build which then gives you a range of enclosure volume which will work acceptable to very good.
You want to keep a 2-way? The same here. With your enclosure and driver cut out, you have no room to fit a midrange driver or mount a separate chamber for it because there's no access to the inside except through the baffle cut out of the bass. You don't have to build it with a removable back or baffle but it's a PITA to glue and fix a separate enclosure there. It has to be precise too because otherwise you might end up having problem with the tweeter placement. The edges are the same, you don't have any space left for a bevel or rounded edges to reduce the edge diffractions.
It looks likey you'll even have problems with the placement of drive-in nuts because the driver is too close to the walls, you already had to route off the wall to make the driver fit.
If the datasheet shows the woofer's performance in a sealed 50L box, that's good performance. I think you should still tune the box with ports, (conservatively, like just over a 3rd order slope). That way, if you want to run without subs you can unplug the ports and you'll have low end extension which is still very controlled. At times I think it's nice to listen to just speakers without the sub. They interact with the room differently. Plus night time listening with the sub off will have more bass but not carry as far, if that's important to you.
I think that's a good calculator, but I'm not entirely sure.
For the tweeter you'd put in 1700hz and 7 ohms. The woofer is also 7 ohms, but it has a very, very early and fast rise in impedance... it's already up to 20 ohms by 2khz. I didn't see this before... It will absolutely need a zobel network (impedance equalization circuit). Excellent news is the same one will work for your 2khz 12db/oct crossover and the 1.7khz 24db/oct!!
For the tweeter, try to run the 2khz crossover you have with it without the notch filter first. If it distorts or sounds off, then a notch filter is needed. If it's not, it also won't be needed for the 1.7khz 4th order. Even if it ends up not being required, using one will improve sound quality a bit, so I'd recommend making it anyway. Benefits would be lower THD at all levels, and less thermal compression at high levels
I forgot to mention, you shouldn't lower the crossover point of the 2k 2nd order crossover that you have by changing the caps. For a 2nd order filter, 2khz is probably as low as you can go with the tweeter with a shallow 12db/oct slope.
There is one case you might be able to: if, with your 2khz 2nd order XO, you get no distortion at high levels with no notch filter. You could then add a notch filter and lower the point to 1.7khz. I don't know if it would be possible to do this by only changing the capacitors though - you'd have to change the woofer's crossover point, and I think the inductor would have to be changed for it instead (if you're only changing one). Doing these things might then cause the tweeter's inductor and woofer's capacitor to become sub-optimal choices, and cause the filter to perform a bit oddly.
1.7khz 4th order is what you should do if horizontal dispersion needs improving from 2.0khz 2nd order
There is one case you might be able to: if, with your 2khz 2nd order XO, you get no distortion at high levels with no notch filter. You could then add a notch filter and lower the point to 1.7khz. I don't know if it would be possible to do this by only changing the capacitors though - you'd have to change the woofer's crossover point, and I think the inductor would have to be changed for it instead (if you're only changing one). Doing these things might then cause the tweeter's inductor and woofer's capacitor to become sub-optimal choices, and cause the filter to perform a bit oddly.
1.7khz 4th order is what you should do if horizontal dispersion needs improving from 2.0khz 2nd order
Since I ordered the tweeter and cross over, I'll see how it sounds. If the cross over needs any change, I'll buy all the components and make a new one from scratch for a 4th order.
I ordered the Wavecor TW030WA13 30mm tweeter and its rated at 4 ohm, so if you look at the spec graph, its 4 to 4.5 ohms over its operating range. I picked that over the 8 ohm version because its 93db rating. I may have to add a small resistor to match the woofer output.
It only got 93dB because that's a 4 Ohm driver and the spl is given at 2,83V, which is 1W at 2,83V. That means because half the impedance, that's the level at two Watt instead of one. The level with 1W is -3dB, which is 90dB.
That also means, if you look for a tweeter (or any other driver) and need a specifit spl, always look at how the measurement was taken or you might not get what you want and need because if the driver got half the impedance it also gets twice the power (that's the +3dB) and the driver might be over it's power capability. Some manufacturers state the power at 1 Watt, most measure at 2,83V.
You can develop a crossover with a serial resistor perfectly fine. Though, to lower the level it's usually better to use a voltage divider (one R in series, one after that one in parallel) instead of a single serial resistor because the crossover point will shift with a changed impedance. That means, if your crossover fits perfectly but you need to take off 1-2dB and increase the value of the resistor, you need to change the parts of the high pass filter as well. If the level is adjusted by a voltage divider, the impedance the crossover 'sees' hardly changes and you don't have to replace the other parts and start fiddling again with the filter function.
I thought you got the 8 ohm version, to match the 8 ohm woofer. The 4 ohm model is 90db/w (the 8 ohm version was 90.5, but it should be fine).
To make the tweeter work with your 2khz 12db 8 ohm crossover, you need to put 3-4 ohms in series with the tweeter, 20 watts worth. It will make the impedance the crossover expects, and attenuate the tweeter by the right amount. The exact value can only be determined by trial and error, and it might not be able to work exactly right - for the slope to be in the right place the tweeter might have to be too quiet. This is one of the reasons a custom crossover works best.
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Somehow I didn't see your post before I sent mine. We said very similar things lol
I think the voltage divider method allows for some attenuation of the impedance peak too, which would be good if he'd be able to use it with the 2k crossover he has
The crossover he has is unfortunately for 8 ohms
At this point you're probably better off forgetting about the 2khz 2nd order crossover you bought, it's probably not going to work, and if you get it to work it will only be after a tonne of work. First you're going to have to find the exact resistance required by the crossover to get the slope in the right place. Once you do, if the tweeter is still loud enough (and the odds are it won't be), you'd need to pad it down to the correct level with 5 watt resistors that are fractions of an ohm.
Instead, you should spend the time making and tuning the 4th order crossover. When you pad the tweeter down to the right level, the impedance peak at resonance will also be attenuated, possibly negating the need for a notch filter
Instead, you should spend the time making and tuning the 4th order crossover. When you pad the tweeter down to the right level, the impedance peak at resonance will also be attenuated, possibly negating the need for a notch filter
If your amp is good to 4 ohms (I assume it is), you can keep the 4 ohm tweeter - just use exactly 4 ohms for the crossover parts calculation. If you go with the 8 ohm tweeter, use 7 ohms. You should post here to verify the parts are correct for your tweeter before ordering them, to be sure. I can't verify, but someone else should be able to. Both tweeters will work for your purpose, and if your 4 ohm tweeter has already shipped it might be easier to just keep it (with the voltage dividing resistors to match sensitivity attenuating part of the impedance peak, possibly negating the need for a notch filter).
Your woofer needs the impedance equalization circuit, which I see there are calculators for. I don't know the math to verify if the parts they suggest are correct, so maybe you could make another thread asking for help with each.
The woofer's around 7 ohms in the middle of its passband, and up to ~18 ohms at 1.7khz. I think the zobel will keep it at the 7 ohm value
Your woofer needs the impedance equalization circuit, which I see there are calculators for. I don't know the math to verify if the parts they suggest are correct, so maybe you could make another thread asking for help with each.
The woofer's around 7 ohms in the middle of its passband, and up to ~18 ohms at 1.7khz. I think the zobel will keep it at the 7 ohm value
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To make sure the tweeters and crossovers worked, I temporarily placed them on top of the cabinets. I built the tweeter and woofer crossovers on separate scrap peg board and used scrap copper to solder all the components together. Took way too much time and thank goodness they will be hidden.
Overall I thought they sounded fairly good even before cutting a hole for the port in the front.
After playing the system yesterday afternoon at fairly high SPL, I determined the 4 ohm tweeters were too "hot" and ordered resistors that should attenuate the tweeters by 6db to closer match them to the 8 ohm Dynaudio woofers. I knew that would likely be the case when I ordered the 4 ohm tweeters and that's OK. But at least the woofers performed well.
I also ordered walnut veneer which means I'll have to move them back to my workshop, remove the woofer, put the cross overs into the cabinet, cut a hole for the tweeters just above the woofer, make a grill, paint the rear and bottom base satin black. That should finish them.
It should be interesting to compare them to the JBL 4312s I bought & restored 2 months ago, the Original Large Advents I given 2 weeks ago, and the AR-9s I restored 2 years ago.
Everything is set up in a medium size living room (about 270 sq ft or 2100 cubic feet if you count the vertical) with open access to the foyer and dining room at the rear. I don't think our living room is the best but not bad either.
This has been a good learning exercise and helps avoid boredom.
That's a big cabinet for just one woofer. I think I would get me another woofer if it would fit below the one you already cut out for and port it. I have no recommendations for a tweeter as I have no idea what those particular Dynadios sound like.