I've had this sub and dayton 1000 watt plate amp in a 4cuft sealed and an 11 cuft ported box. I'm now wanting to try a sonotube. I have 24 inch sonotube that I've cut to 54 inches tall which should net about 13 cuft. Parts express recommended a 3 inch port 9.5 inches long for a 18hz tune which seems small. Online port calculator came up with a 6 inch port 17 inches long. Is either of these correct?
Without running the numbers, both are correct. Increase the diameter and you'll have to increase the length to keep the same tuning. You're trying to keep the airspeed below an audible level, and a 3" port might have the air moving too quickly, which is why you'd want to go larger. Going larger in the port also reduces the volume (not SPL) of the sub, so you'll need to take that into account.
Do those Dayton plate amps have any kind of built in HPF? If not do you have some way to implement one?
In that size enclosure I'd personally go for a little lower tune and aim for 16hz. A single 6" port would only need to be 18.5" long and max port velocity (w/ 600w and a HPF at 16hz) only reaches 24m/s. I choose 600w because that is where the driver reaches xmax in this enclosure. If you have some way to do 4" ports, then 3 - 4" ports would work and bring port velocity down to 18m/s, but each would need to be 37.5" long. IMO I think the single 6" port will work perfectly fine and if you flare the ends shouldn't chuff or whistle at all.
If that's the case, then I would also tune the enclosure to 18hz to take full advantage of the port output. The single 6" port should work just fine IMO.
The guy I talked to at parts express said the 1000 watt amp would be fine as long as I don't turn it way up. That way it won't put the full 1000 watts out. I don't know how I'm supposed to tell how many watts it's using at a given volume. It worked fine in 11cuft. No odd noises or any other sign that it was being damaged.
So long as the amp actual does have an 18hz HPF built in then you can probably get away with running the amp up to full output (though I'm willing to bet the Dayton specs are inflated and it probably only puts out closer to 800w or so at full power). Just know that you will be somewhat over xmax meaning distortion will be higher. The UM series have a ton of xmech so the driver and suspension should not be at risk of damage, the sound will just be of somewhat less quality subjectively, but I don't know that you will actually be able to hear the difference in distortion of 600w vs. 1000w.
The 13 cuft box you're looking at now is more efficient on the low end even compared to the 11cuft box so the driver does not require as much power to reach full output. This is actually a good thing because you will not be running up against the limits of the amp to get the sub to full volume.
The guy I talked to at parts express said the 1000 watt amp would be fine as long as I don't turn it way up. That way it won't put the full 1000 watts out. I don't know how I'm supposed to tell how many watts it's using at a given volume. It worked fine in 11cuft. No odd noises or any other sign that it was being damaged.
How would I know if I'm running too many watts into the sub? Just by listening for distortion? I have a denon receiver that has audessey. If I set it up using that and don't mess with the settings will that be ok?
I guess what I don't understand is to me it sounds like the amps output is variable based on demand. That it's not always trying to send 1000 watts at all times. So if I want to play something at reference level that would normally need around 500 watts what difference does it make if 1000 watts total is available.
The difference between 500 watts and 1000 watts is 3db, aka "a little louder". Is that your question?
If you have 1000 watt amp and are hitting reference levels with 500 watts, you have a little headroom to go louder. Not much, but a little.
Is this the amplifier you have? If so, I looked over the manual and it did not state that is had any type of high pass or subsonic filter on it. Are you sure it has a high pass at 18hz? The only reason, people are making sure, is that you will ruin your sub if you do not have one. If it is not built into the amp, you can build a high pass crossover and stick it in the sub box. The only issue is the values will be very high and it'll cost you a fortune. You may need a new amp or at the very least get an FMOD high pass at 20hz .
Before you hook it up, you will want to know definitively that it has a high pass at 18hz.
Just talked with a guy from parts express and he said it has a built in low pass filter that is adjustable from 18hz to 80hz. He said that's all I should need.
Reading through the linked thread about measuring amplifiers it looks pretty clear that there is in fact a HPF in this amp. I believe the results of that test state that the level is down 15db at 10Hz. just as you did not experience an issue in your previous 11 cuft box, you should not have a problem with a 13 cuft sonotube.
I don't want to attach the plate amp to the enclosure. I was thinking about just drilling a small hole in the bottom cap and running the wires thru it sealed with silicone. Is there a better way?
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