That'll work, do you have the correction tables for the spl meter you have? I find that using a tone generator works better than sweeps as you can move up very slowly and stop at a frequency if you so wish. If doing this indoors set the spl meter on the ground on a towel ~1ft from the speaker. oh yea, set the speaker on it's side so the port and driver are about the same distance to the meter.
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The plotted cure looks gloomy, but every time I listen or work on one, I think D**m this is powerful.
Question 1 - if they were drastically misaligned, how could the voltage peaks be even and the FS remain @ 30hz? [bench test/tuning]
Question 2 - I did think the 240w plate amp was the best bang for the buck; do “they” enhance the bass around 40hz in the amp circuitry?
Btw, I'm not opposed to trying different boxes/configurations, even speakers, it's all part of the search.......
Question 1 - if they were drastically misaligned, how could the voltage peaks be even and the FS remain @ 30hz? [bench test/tuning]
Question 2 - I did think the 240w plate amp was the best bang for the buck; do “they” enhance the bass around 40hz in the amp circuitry?
Btw, I'm not opposed to trying different boxes/configurations, even speakers, it's all part of the search.......
Answer 1: The resonant frequency of the enclosure is set by the port and enclosure dimensions, not the driver parameters. I posted the calculation.
Answer 2: Some do, some don't. You need to look at the specificatons of the amplifier to see if it does. You can test it easily enough: Connect an AC voltmeter (a multimeter set to a low AC voltage range) across the output of the amplifier. Now drive the amplifier with a frequency sweep and see if its output varies significantly (more than 25% or so) across the range 20 Hz to 100 Hz.
Answer 2: Some do, some don't. You need to look at the specificatons of the amplifier to see if it does. You can test it easily enough: Connect an AC voltmeter (a multimeter set to a low AC voltage range) across the output of the amplifier. Now drive the amplifier with a frequency sweep and see if its output varies significantly (more than 25% or so) across the range 20 Hz to 100 Hz.
Q. #2 Oh really.... I didn't think about that at the time, I could have checked it with volt meter, over the fellow's house now. I bet he’s loving it today, raining like crazy here; it really dips down low when its raining.
Q. #1 I did set it, trial and error method, unusual, but it works. I just can’t figure out why it works, looks like it is right on, even peaks, etc,. Calculation - post 97?
If the box is too large, isn’t it hard to bring up the first peak (20hz or so) and keep the valley where it is supposed to be?
cure = curve (typo)
Q. #1 I did set it, trial and error method, unusual, but it works. I just can’t figure out why it works, looks like it is right on, even peaks, etc,. Calculation - post 97?
If the box is too large, isn’t it hard to bring up the first peak (20hz or so) and keep the valley where it is supposed to be?
cure = curve (typo)
His port has an extreme aspect ratio. Did you remember to increase the simulation port losses to match? Doing that brings the sim results more into line with his measured results.
Sure did, at 90w/97db the port should be compressing -4db at 40hz (should be 90w/101db). Call it a lucky accident but the port dosen't go completely turbulent until ~100db/40Hz/150w, so it's still usable below that wattage, above 100db i'd predict rapid port compression, almost a brick wall. Strangely that port compression probably helps to flatten out the response curve as spl's (85db+) increase. more good luck
back for a couple of reasons:
There was such controversy on this thread I think some may have disregarded this submission.
I came back for a couple of reasons; one, I believe I was vindicated.
Secondly, I chuckle every time I hear one. I have two in the HT and one bolted to the joist in the shop (to free up floor space).
The boxes have tremendous bass, also a unique sound that is quite pleasing and remarkable at the same time.
As mentioned before, I’ve rolled other subwoofers through here; sure, many had there highlights, enjoyed them for a few months and keep coming back to these.
It is hard to believe that they are outstanding for HT and for music; and certainly they would not be as good as a $1,000+ subwoofer, but for a small amount of $$ and a little work, they do sound like one.
I built one for a buddy, used the 240-b watt plate amp (b is bass boost), and that had an extra reward and can still hear it in the back of my mind. When the towel almost got vacuumed into the slot port, all I could think: “you got to be kidding me”.
For some of my critics, I’m sure the ship will sail away and they will be left on the dock; however for the rest of us; it’s a lot of fun, somewhat easy and economical to build.
There was such controversy on this thread I think some may have disregarded this submission.
I came back for a couple of reasons; one, I believe I was vindicated.
Secondly, I chuckle every time I hear one. I have two in the HT and one bolted to the joist in the shop (to free up floor space).
The boxes have tremendous bass, also a unique sound that is quite pleasing and remarkable at the same time.
As mentioned before, I’ve rolled other subwoofers through here; sure, many had there highlights, enjoyed them for a few months and keep coming back to these.
It is hard to believe that they are outstanding for HT and for music; and certainly they would not be as good as a $1,000+ subwoofer, but for a small amount of $$ and a little work, they do sound like one.
I built one for a buddy, used the 240-b watt plate amp (b is bass boost), and that had an extra reward and can still hear it in the back of my mind. When the towel almost got vacuumed into the slot port, all I could think: “you got to be kidding me”.
For some of my critics, I’m sure the ship will sail away and they will be left on the dock; however for the rest of us; it’s a lot of fun, somewhat easy and economical to build.
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Hi,
Vindicated ? What on earth are you talking about ?
The only "controversy" is you refusing the listen to common sense.
Which is still the case, chuckle away to yourself, it is not funny.
Nobody sensible is interested in a design that clearly is very wrong,
can be reworked to be twice as good, or effectively halved in cost.
Its a poor pointlessly isobaric "design", give it up. This is boring.
rgds, sreten.
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Hi,
The idea that another thing wrong, port blocking at high velocity, somehow
vindicates everything else that is wrong with the design is just plain stupid.
Grinch ? resorting to personal affronts is the last resort of the wrong.
No its not if a person is trying to recommend to other people something
that is clearly wrong and there are far better ways of doing it. If you
get something wrong and can't admit it, that is not my problem.
There is nothing personal about my attitude, this thread is full of "its
great" when technically it clearly isn't, by a long way, and trying to
prevent other people being misled by such guff is to me reasonable.
It is boring. 116 posts and the OP is still tediously insisting it works.
It works, but very poorly compared to correctly designed options.
rgds, sreten.
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Fair enough, I have these drivers on the shelf and would build something else too.
I think that is flatting out the response.
I don’t think any one commented why the boxes tune perfectly, the high and low voltage peaks are dead even and Fs is 30hz. I’ve tuned a lot of BR speakers, getting the peaks to match and Fs at the desired point (valley), is not that easy to pull off.
I don’t think any one commented why the boxes tune perfectly, the high and low voltage peaks are dead even and Fs is 30hz. I’ve tuned a lot of BR speakers, getting the peaks to match and Fs at the desired point (valley), is not that easy to pull off.
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