ML Sub Pics-almost Done

This project was entirely an exercise and was done simply for the love if DIY. There are no t/s parameters to be found for the ML subs, so I pretty much built a box making some educated guesses and took a blind shot in the dark with the gun backwards using my pinky finger! I will post thoughts on the sound eventually as it is not done yet. I still have insulation to install and some finishing I want to do to the exterior of the box. I hope you guys like it.











Dominick

Very nice! Love the build pics. I'm always too lazy to do that while I'm building.

Dominick... that's just plain awesome! I wish I had the time to learn how to build cabs...

Joey

Both of the ports look to be a different length? That would usually result in different tuning between the two subs.

The box looks very well built, and I'm totally jealous that you have found some ML drivers

Right you are Dominator,
I did some reading and although I cannot remember where now, I read about a company that was using a dual ported box similar to mine.

There goal is to create two resonant peaks producing greater bass extension. For example at 20hz and 40hz. Fact:The lower the frequency goes, the less the human ear can hear even with the same output. The idea is to create a large peak at 20hz and a smaller one at 40hz. To the ear, this might sound like a flat response even though the actual output is greater at the lower frequencies.
Anyway-this project is no where near that technical, but the article suggested that there long port was approximately twice as long as the shorter one. My short port is 15 inches and my long port is 31 inches.

Again let me say, this was a total shot in the dark and for fun given that I had no T/S parameter. There is some cancellation that I have yet to really try to narrow down and I am suspecting that the long port sub is behaving more like a free air sub than a ported sub. Its port just may be tooooo long! I dunno.

Once the insulation is complete-I will listen critically. But two tuning frequencies was the goal.

Thanks,
Dominick

I see, there is an enclosure design somewhat like that only one is in a bandpass arrangement, it's called an A-B-C box.

In a ported design, the port should not be able to be too long, the immediate airspace near the woofer (usually referred to as the chamber) is what can be too large or too small..... but the port's cross section can be too large, though yours look to be plenty large but not what I would consider huge.

Thats good news,

I am hoping to make some monumental gains from the final touches. I was also thinking that I may have many small air leaks in that last panel (back panel) I attached. I was so excited to get it running that I sort of skipped to the end for a preview.

Thanks,
Dominick

From what I've read In standard ported subs....anechoic response should be flat down to your tuning point (and then drop off steeply afterwards) so shouldn't require any sort of boost at 40Hz. Generally you pick your tuning point to be after the driver starts rolling off naturally, so that it negates that roll off. Your driver will likely run out of power handling ability before Xmax at 40Hz. The boominess you're hearing might well be the increased output at that point. You would likely gain more headroom down LOW (as well as having flatter anechoic response) if you tuned both subs with the same tuning point down low. I can't wait to see your tests of both the sub as a whole and of the individual drivers.

I have now added the insulation, feet spikes, gasket rings, and touched up the final panel sealing.

The improvement is just what I was hoping for. It has become much more punchy and tones have a more distinct beginning and end. Although it is still not perfect, the above additions practically doubled its performance.

I do know that I probably should have used a thicker baffle like IWalker. His is 2 inches thick. Me thinks he must have gold in there for insulation!lol I am getting what seems like excessive wall vibration through my 3/4 MDF panels. But I am just guessing at this point. With eq tuning on the amp, I have eliminated most of the boominess inherent to ported subs.

It seems like every cd throws me for a loop right now. Some sound excellent and I cant help but smile and then others I find myself wondering if there are certain bass notes almost missing!? I think that some cancellation is occuring and it is hit or miss depending on the cd. I wonder how it will do with HT.

Dominick

The nulls you are hearing can have a lot to do with room modes (peaks and nulls caused by reinforcement or cancellation related to your room dimensions and the frequencies that match with them). The EQWizard program we talked about should help you identify your in room freq. response. Glad to hear everything is sounding better! I swear by overpadding boxes, as long as you keep the padding away from the back of the driver. I would still be interested, if possible, to hear results of testing each cone independently. See if you still hear the nulls you mentioned (which would suggest room modes) or if it's some cancellation as you suggest (but I wouldn't expect, as the drivers should be operating in phase)

Yeah, the 1.5" walls and 2.25" baffle on my sub just aren't moving at all. It was a GIANT pain to double box it with the kind of glue I was using but was, I think, worth it.

This is the Dayton amp that I am using with the ML subs. I am pretty happy with it and was even more pleased when I opened her up. Can you see why?

Dominick

source?

Maybe I missed it Dominick, but where did you get the ML drivers?

After much searching and waiting, I found them on ebay for $180.00. $60.00 per driver...I thought that it was a fair deal to say the least.

What do you think?

Dominick

Dominick22 said:

After much searching and waiting, I found them on ebay for $180.00. $60.00 per driver...I thought that it was a fair deal to say the least. What do you think?Dominick

Click to expand...

I think it's a very good deal, but again, where did they come from (before they got to Ebay?) I wonder if one could simply order them as a part from ML (did you try that first?)

he got them as replacement woofers for his descent when he had a problem-but it turned out to be the amp that needed replacing. ML said to just keep the woofers though-so he sold them.

Dominick

Dom, Nice work.

Now, post some measurements

Just a quick update...

I ran a bass test just using a cd and my ears. It plays 10 second intervals from 5 hz up to 100 hz in 5 hz increments.

What I noticed most about both the ported and sealed sub I built, was that there was a significant resonance at 65hz and 75 hz. I thought this was pretty wierd. Especially since they are completely different designs.

And why are there 2 distinct resonances? My only conclusion is that it was the resonant frequency of the speaker...but can a speaker have 2 resonances???

Dominick

Dominick22 said:

And why are there 2 distinct resonances? My only conclusion is that it was the resonant frequency of the speaker...but can a speaker have 2 resonances???

Click to expand...

Why not...it is like a harmonic. There are TONS of overtones and stuff when you play a single string on an instrument or a note on any instrument for that matter... Why shouldn't a speaker have one more probably MANY resonances?

Dominick22 said:

Just a quick update...

I ran a bass test just using a cd and my ears. It plays 10 second intervals from 5 hz up to 100 hz in 5 hz increments.

What I noticed most about both the ported and sealed sub I built, was that there was a significant resonance at 65hz and 75 hz. I thought this was pretty wierd. Especially since they are completely different designs.

And why are there 2 distinct resonances? My only conclusion is that it was the resonant frequency of the speaker...but can a speaker have 2 resonances???

Dominick

Click to expand...

Hi,
Unless you are testing this outdoors, or in an anechoic chamber, you are seeing room resonances in addition to any speaker resonances. In an untreated room, the room resonances can easily be greater than 20dB, even for a speaker with otherwise flat frequency resonse. This is why room treatments and sub equalizers can make such a huge difference in a systems sound.

Peter

Peter,
I suppose this would be the most logical explanation since I tested them on the same wall.

But just for arguments sake...all speakers are said to have a given resonance at some frequency. Can a speaker have two true resonant frequencies? I would think that one speaker could not since the resonant frequency has more to do with the mechanical factors of the speaker?????

Do all speakers have multiple resonances-is this common or uncommon?

Thanks,
Dominick