Jims 3 way speaker build

[jimbones]

Update: I ran a SIM in a program called SpeakerBuilder Pro 2.0 and it says my Port should be 23.5 inches long!! Thats a bit more than twice what Win ISD specifies. The program says that if I go to a 3 inch port the L is 12 inch.

[rpb]

The Q will not matter much at all. An option to consider, is changing the shape of the mid chamber. ie sloped sides, etc.

[jimbones]

Doing some more homework I find that I made the mid enclosure on the large side, not so much so but I can make the mid enclosure 2 inches shorter and still have a good Q of 0.75 sealed. I believe the big box is in the way and not sure if it is impeding air flow.I fixed the air leaks on one speaker. I will also reverse the port and put it external to the cabinet and play with tuning.

[jimbones]

DeZZar really quick and dirty interior volume trapeziod 149.5 sq in x 38 in height is 5681 cu in or 3.3 cu ft.
There is a .2 cu ft enclosure for mid, allow 0.1 for the woofer, 2 braces 3/4 inch thick = .0007 cu ft, the vent = 0.065 cu ft and the tweeter is negligible since it is mounted on a 1 inch thick baffle. Crossovers are external for now. So basically I allowed 0.8 cu ft. Win ISD says 2.5 to 3.0 cu ft. I should have over 2.5cu ft. The only thing is there are volumes of air that maybe acting as resonators since air can flow around certain structures but is limited.

[jimbones]

Dezzar, im a bit busy today but I have the info. let me put it together and I will post tomorrow. Thanks for checking in I really appreciate it.

[jimbones]

Dezzar, im a bit busy today but I have the info. let me put it together and I will post tomorrow. Thanks for checking in I really appreciate it.

[DeZZar]

- recheck the exact NET volume of the cabinet. Subtract braces, midrange isolation box, anything else solid.
- with the leaks plugged up, take a fresh impedance measurement - take fresh woofer nearfield and port nearfield

- do you have detailed drawings of the cabinets you can attach? Something showing all the internal dimensions etc?

[jimbones]

Found about 3 small air leaks in the rear panel. I used incense stick and played a bass heavy track and watched the smoke curl. I'll fix those but it wasn't much.

[jimbones]

Interseting. I am using a NAD C272 while I am in this phase of testing the XO. A buddy brought over a Peachtree GaN400 and it improved the overall sound by a mile. The bass improved as well. I need to borrow it again and spend some time with it to see if it was the NAD amp that had crappy bass.

[rpb]

If you didn't already, I'd check to see if the padding resistors on the mid are getting hot, and possibly changing value.

Speaker location can make a big difference. Try 32" from the side walls maybe. Room software may predict the response.

[johnny5jz]

Is 2.4 cubic feet total enclosure volume not subtracting the port and woofer volume? I don't have my modeling software in front of me, but if 2.4 cubic feet is your total volume, I suspect your enclosure is a bit too small and you are getting a large peak prior to rolloff. You may try lengthening the port and tuning even lower to even out your response. I can try modeling it later and see if my suspicions are correct.

[jimbones]

I am really struggling with the bass. It is a quality and quantity issue. There seems to be resonances that are muddying the sound. Its not clear and punchy. At times it seems loud and at others it seems reticent. I was thinking about whether to post here or start a dedicated thread to resolving this.

So far I have played with varying amounts of stuffing inside the cabinet. I also tried plugging the port (very little difference which I am suspicious).
The cabinet itself does not seem to be vibrating excessively. It is braced. I Have the cabinet minimum of 40 inch from side walls and 4 feet from front walls.
I recently lined the port (ala Troels) with carpet padding. (see pic). Seems to quiet some stuff but overall NG.
The things I have yet to do are playing with varying port lengths and diameters. I have read where some people say they had to make the port half the length of what WinISD advises. Sounds like too much….

Questions I have:
Could the cabinet shape be a contributor? Narrower at the rear and wider at the front?
The volume is 65 litres. Or about 2.4 cu ft. and the cabinet is tuned to 33hz That seems correct, no?
Could the port dia be too big? Maybe a 3 inch port?
I have a 6.5 mh coil/110uf cap on the woofer. Not sure a parts change will help. I will listen to the woofer by itself.

In the end I am willing to give up F3 for quality. I have GR Research subs to augment these. I can go to high 30’s or 40hz?





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[rpb]

Ive had some time to just relax and listen. I made a few tweaks but in the end I believe it is the bass that is throwing me off. The bass is very strong at times. This may be due to the fact that it is a fairly efficient driver and gets gain from the floor boundary. Ive played with the mid and tweeter levels to see if they can keep up and I think either the box tuning is off or the woofer is just to loud and not sure how to remedy this.

Try sealing the port. Look at your box sim to see the difference in response. Then see if there is boom, or not.

Rooms alter the bass considerably. You may have a peak at a specific frequency caused by the room. You could measure bass at your seat, and see. Don't expect it to be flat. Just look for standout peaks.

I believe that a high dcr coil could shave a dB or two off the woofer response. Tuning lower could help as well.

[jimbones]

Ive had some time to just relax and listen. I made a few tweaks but in the end I believe it is the bass that is throwing me off. The bass is very strong at times. This may be due to the fact that it is a fairly efficient driver and gets gain from the floor boundary. Ive played with the mid and tweeter levels to see if they can keep up and I think either the box tuning is off or the woofer is just to loud and not sure how to remedy this.

[rpb]

so this is the XO I have in play now. I had another listener come over to hear it and it sounds real nice. I think I need to pause and listen for a bit and pause making changes until I get real familiar with the speakers. Then I can refine further. One note the tweeter polarity should be shown as in phase. For some reason in the SIM the results are better reversed but in reality it is better In Phase

I put your xo in a sim, and it looks very good!