Hello,
I'm struggling to get something remotely acceptable on this crossover. I always seem to be pushing the cap values too high to be practical (cost) to force a curve, so I'm clearly doing it just wrong.
I'm trying to see if I can get an acceptable response curve with 3 drivers. Two drivers are smaller full range 8ohm 4 inch drivers that will be wired in parallel (4ohm final load). One will face forward, the other faces up on top (Castle config with a WAW/FAST). The bass driver is a 4ohm 8 inch driver. I was thinking of crossing around 200hz or so. I can't seem to do a good high pass and low pass setup on these. I wanted to set a high pass on the bass driver to drop it off under 25hz to avoid excursion problems. And a low pass on it to be able to better crossover around 200hz to the full range drivers.
I've attached my Xsim model with the FRD/ZMA and drivers and all in there. I removed the bad circuit stuff I had going on.
Any advice or help on how to better approach this would be great. The stock curve I see without any crossover stuff is actually what I would be happy with, but I can't seem to get back to it when I start adding crossover components.
Thanks for any thoughts or help. 🙂
Very best,
I'm struggling to get something remotely acceptable on this crossover. I always seem to be pushing the cap values too high to be practical (cost) to force a curve, so I'm clearly doing it just wrong.
I'm trying to see if I can get an acceptable response curve with 3 drivers. Two drivers are smaller full range 8ohm 4 inch drivers that will be wired in parallel (4ohm final load). One will face forward, the other faces up on top (Castle config with a WAW/FAST). The bass driver is a 4ohm 8 inch driver. I was thinking of crossing around 200hz or so. I can't seem to do a good high pass and low pass setup on these. I wanted to set a high pass on the bass driver to drop it off under 25hz to avoid excursion problems. And a low pass on it to be able to better crossover around 200hz to the full range drivers.
I've attached my Xsim model with the FRD/ZMA and drivers and all in there. I removed the bad circuit stuff I had going on.
Any advice or help on how to better approach this would be great. The stock curve I see without any crossover stuff is actually what I would be happy with, but I can't seem to get back to it when I start adding crossover components.
Thanks for any thoughts or help. 🙂
Very best,
There are some things to bear in mind when you do this, such as accounting for the power distribution, since this isn't included in single measurement work like this.
It could be done academically, such as assuming the higher frequencies don't overlap in space although Xsim assumes they will. Therefore you might let the higher frequencies shelf upward in the simulation, knowing they won't do that directly from the speaker. You'll want to discover the frequency where this applies. It will be related to the baffle step and the driver size. You can also add resistance on listening test.
Speaking of the baffle step, this is another factor to account for. You might also use a combination of simulation and listening test to determine where and how much.
The other issue is the low impedance which the woofer is showing in the region where the crossover interacts with the impedance peak. You may find the output is increased there.
It could be done academically, such as assuming the higher frequencies don't overlap in space although Xsim assumes they will. Therefore you might let the higher frequencies shelf upward in the simulation, knowing they won't do that directly from the speaker. You'll want to discover the frequency where this applies. It will be related to the baffle step and the driver size. You can also add resistance on listening test.
Speaking of the baffle step, this is another factor to account for. You might also use a combination of simulation and listening test to determine where and how much.
The other issue is the low impedance which the woofer is showing in the region where the crossover interacts with the impedance peak. You may find the output is increased there.
Thank you so much Allen, that gives me a great start.
Now to see if I can find affordable 330uf and 180uf caps. Those values seem to be very expensive. I was running into this issue as well when trying to adjust the filters.
Any suggestions for sourcing similar caps to these appreciated!
Very best,
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I can get a pair of electrolytics to put back to back, retail available locally for around 50c. Non polar ones tend to be more expensive, but once you mention the word crossover, they get much more expensive.. so don't..
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Last thing, I think...
Do you think it would be better to use two full range drivers at 8ohm and wire parallel at the crossover for a 4ohm load there, and the 4ohm bass driver? Or would it better to wire two 4ohm full range drives in series for 8ohm load at the crossover, and the 4ohm bass driver at the crossover? I'm used to dealing with wiring same-resistance speakers in different configurations, but mixing two different resistances and doing it with a crossover is new to me.
Very best,
Do you think it would be better to use two full range drivers at 8ohm and wire parallel at the crossover for a 4ohm load there, and the 4ohm bass driver? Or would it better to wire two 4ohm full range drives in series for 8ohm load at the crossover, and the 4ohm bass driver at the crossover? I'm used to dealing with wiring same-resistance speakers in different configurations, but mixing two different resistances and doing it with a crossover is new to me.
Very best,
Ok thanks,
How about for the design purpose on the crossover, if the two full range drivers are in series (4ohm + 4ohm) at 8ohm versus in parallel (8ohm & 8ohm) at 4ohm, does that matter at all for the purpose of the above crossover network? I believe those two were 8ohm each that I had loaded into XSim. Or does that not matter here?
Very best,
Thank you so much; I'll try this.
Namely I just wanted to make sure that if I did a crossover like you showed above and the two 4ohm drivers were wired in series for 8ohm and then soldered to that crossover, that it would be similar to the above or if it would be different.
I realize I can't really account for the 2nd full range driver firing up relative to the full range driver firing forward simply. My understanding is that it really is just there to help with adding scatter to the room and making it sound more spacious. I've never done that, so I thought it was interesting, like the castle speakers I see in the full range threads. Figured, why not give it a go and toss in a bass driver since I have them laying around.
That said, do you think that changes how to design the crossover circuit or any other considerations on the crossover circuit, the one driver facing up and not really aligning with the other driver?
Very best,
Below 1khz speakers are mostly omnidirectional so the top-firing (or side-firing) drivers still contribute a lot. May I suggest that before you soldered the XO to simply compare the candidates using electrician's cap and alligator-clipped wire. Takes only minutes to try them all and fine-tune LRC values.
Thanks; that is a good point. I can certainly test it before making it a permanent crossover. I have the alligators and stuff to do it.
I thought about just wiring it up and measuring the woofer (near field) and the full range drivers (far field, gated via impulse response) and making my own FRD/ZMA files and trying to go that route for the crossover, but my stopping point seems to be the crossover itself. It's one of those things I just haven't gotten comfortable with, hence the thread.
Very best,
When I tried monster caps high-pass (Jantzen crosscaps with std blues) I didn't like the sound. I think the XO is going to depend somewhat on the relative positions of the drivers (acoustic centers) due to interference. When I tried something similar (6x10 vintage alnico) I had one OB-U, one sealed firing sideways with inductor-BSC, one bass-only, to reduce their overlaps.
Any thoughts on the following?
I am not really going for flat, a slight `V' response simply due to preference, as I like a little more warmth and a kiss of sparkle for stereo music listening (keeping in mind these will not be corner loaded nor up against a wall, but away from the wall in a room).
In theory, the frequencies above 1kw should start to drop by at least -3db as that driver will be faced up, so the response curve below would roll down by about -3db maybe less as it goes up from 1khz. This is my assumption, but I would have to listen and measure to see how it actually behaves and adjust as needed. The hump in the bass driver will actually shift left and center over 30~31hz as I would be changing that via bass reflex porting at that frequency (see WinISD model below for the bass driver).
I've re-attached the crossover file for any suggested changes.
I modeled in WinISD how two of the RS100's would model in a sealed chamber together at 0.75 ft^3 and QTc 0.578. The lower chamber with the bass driver is bass reflex with a port tuned at 31hz in a 2 ft^2 net volume. I tried to model how they would look without a crossover at the same 4 meter distance with just 20 watts of signal.
For excursion, the two full range drivers don't reach xmax until 80hz at 20 watts. The sub driver never gets to xmax at 20 watts, down to 20hz so I feel like I can get away without a high pass filter as none of my content for music gets down below that, and doesn't need to be louder than this really, but it can still take more power and not get to xmax. The crossover near 200hz keeps the full range drivers from getting to xmax even at 40 watts as it doesn't get to xmax at 40 watts until 100hz and it slopes off before that.
Very best,
I am not really going for flat, a slight `V' response simply due to preference, as I like a little more warmth and a kiss of sparkle for stereo music listening (keeping in mind these will not be corner loaded nor up against a wall, but away from the wall in a room).
In theory, the frequencies above 1kw should start to drop by at least -3db as that driver will be faced up, so the response curve below would roll down by about -3db maybe less as it goes up from 1khz. This is my assumption, but I would have to listen and measure to see how it actually behaves and adjust as needed. The hump in the bass driver will actually shift left and center over 30~31hz as I would be changing that via bass reflex porting at that frequency (see WinISD model below for the bass driver).
I've re-attached the crossover file for any suggested changes.
I modeled in WinISD how two of the RS100's would model in a sealed chamber together at 0.75 ft^3 and QTc 0.578. The lower chamber with the bass driver is bass reflex with a port tuned at 31hz in a 2 ft^2 net volume. I tried to model how they would look without a crossover at the same 4 meter distance with just 20 watts of signal.
For excursion, the two full range drivers don't reach xmax until 80hz at 20 watts. The sub driver never gets to xmax at 20 watts, down to 20hz so I feel like I can get away without a high pass filter as none of my content for music gets down below that, and doesn't need to be louder than this really, but it can still take more power and not get to xmax. The crossover near 200hz keeps the full range drivers from getting to xmax even at 40 watts as it doesn't get to xmax at 40 watts until 100hz and it slopes off before that.
Very best,
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Also, any thoughts on incorporating an Lpad like this to attenuate the full range drivers? Seems like it would be a nice thing to have to be able to adjust it as needed in different rooms and listening distances?
https://www.parts-express.com/L-Pad-50W-Mono-3-8-Shaft-8-Ohm-260-252?quantity=1
Very best,
https://www.parts-express.com/L-Pad-50W-Mono-3-8-Shaft-8-Ohm-260-252?quantity=1
Very best,
Ultimately I can build the crossover externally which allows me to swap polarity and test everything externally before putting it together permanently I think.
Very best,
Wow that's smooth! Thank you so much for that. Something to work towards.
I'd have to figure out how to actually assemble and wire those series that end in ground (negative return).
Very best,