Jims 3 way speaker build

[rpb]

Yes lots of info to digest. The speaker is 3 feet from side wall and 4 feet from front wall

In that case, I'd pad the mid a few dB as others have suggested. You can try one resistor, or two in your sim, and see if either will change the smoothness of the roll-off, or require changing the caps, and coils slightly.

[jimbones]

OK so the port is trimmed to 10 inch and I have 3 inches from rear panel. That should be ok.

[johnny5jz]

Run a DATS sweep on the woofer in the box and see where your tuning ends up. I usually find that WinISD calculates my ports on the long side and I end up cutting them shorter to get the correct tuning.

[jimbones]

johnny5jz will do. I use the formula that Precision Port gave me but it must be a misprint as it makes no sense.

[jimbones]

OK Im back. I just wanted to spend a bit of time listening to them. I am not getting the impact of the low bass that I had expected from this setup. I will do a sweep and just to let you know the Lv is 10 inch and should be tuned to 33hz.. If someone can help me pinpoint why the low bass seems absent

[rpb]

OK Im back. I just wanted to spend a bit of time listening to them. I am not getting the impact of the low bass that I had expected from this setup. I will do a sweep and just to let you know the Lv is 10 inch and should be tuned to 33hz.. If someone can help me pinpoint why the low bass seems absent

Where are you listening? Shop? Living room? Is the speaker 4' from a wall, or out in the middle of a room? One speaker, or two? Did you pad down the mid, and tweeter? Did you make any close mic measurements like I mentioned?

Are you using an AVR? Is there any chance that the speaker selection is set to small? Anyone fiddling with the tone controls, like kids?

[jimbones]

rpb answers below
listening room, both speakers 3 feet from side wall and 4 feet from front wall. Padded doen mid only. Using a NAD 398 power amp just for testing. No tone controls. I will next check polarity etc. stay tuned

[jimbones]

L & R speakers independently Fr and Impulse. The polarity must be good because I inverted one and it got way worse. next I will pad down mid and tweet.

[DeZZar]

Per my last post. I tried level matching your measurement results to what would be expected based on driver spec - tweeter and mid should both be playing around 89db based on specs and your woofer with full BSC will be down around 85db. Both mid and tweeter will require padding to balance the speaker.

Might be a slightly unorthodox approach to just level up your frds but the accuracy of your measurements is dubious so just trying to work with them as best as one logically can.

The link I sent you to measurement procedures which includes taking woofer and port nearfield, combining them accurately and merging them with far field is well worth the read and will give you a much better picture of what's happening with your bass performance. Of course you also need to measure the thing up off the floor but understand that's not possible so it's just a level of inaccuracy that has to be worked around.

Bottom line, without correctly padding down both tweeter and mid, these are going to sound thin and the bass performance will be subject to finding some sweet spot where room gain compensates for the lack of BSC.

[jimbones]

got ya. i am padding the mid and tweet and it is helping. i think i need to pad a bit more. i also checked with Madisound regarding the tuning and it wasn't so clear on their answers (16 inch vent, vs my 10.5 inch vent and shelving below 45hz) The ran a sim in Bass BoxPro.Either way they said I need to let the woofer break in as it has less than an hour on it..

[rpb]

A close mic measurement on the woofer will show you what the tuning frequency is! Very easy. Just don't stab the driver with the mic like I did last night! (No damage, just bumped it.)

On my speaker... I had it sounding good,but it needed padding like yours. Adding resistors fouled up everything. You will likely need to verify roll-offs, etc.

[rpb]

Verify roll-offs after listening, and getting tonal balance where you like it. . Sneak up on it.

[jimbones]

Im sneaking alright. little by little

[DeZZar]

On the port tuning side of things - calculations are good for a ballpark starting point - and in some cases end up being spot on but in just as many cases need some fine tuning. Once you have the box with final stuffing etc then you can throw the formulas out and just focus on your measured results.

Woofer break-in etc will have no effect on the box tuning - box tuning is a relationship between the air volumes of box and port, independent of the woofer. Its how the box tuning affects the woofers performance that will change with driver break-in. This is where the near-field measurements for woofer and port, and the appropriately combined sum tell you if the tuning of the box is getting the right magnitude response from the woofer+port combination. If you see a peaked up sort of bass response, tuning is too high for that woofer. If you see a suppressed gradual rolloff and a higher f3 than expected (more like a sealed response), the tuning is too low for the woofer.

[jimbones]

I don't have any stuffing in the box.only padding on the wall

[jimbones]

DeZZar I didnt think that you are even supposed to stuff a vented cabinet?

[jimbones]

DeZZar I didnt think that you are even supposed to stuff a vented cabinet?

[DeZZar]

I don't mean fill the cabinet up, I'm just referring to the material you would need to add to tame those box resonances - polyfill top and bottom etc - tuning has to be done with those final quantities in place.

[jimbones]

here are the near field measurements for the woofer and port. weird the tuning looks high

[rpb]

That does look odd. Were you playing only one speaker at a time? How close to the woofer was the mic? I'd suggest about 2". Can you do gated, with a long gate time?

[jimbones]

i was about 1/4 to 1/2 inch from cone. I was flush with port opening. I did 2.5 msec gating. We also did other freq tests and it is fairly flat to about 60 then it drops and there is a shelf such that the output at 25hz is the same as 40 hz. there is little "weight" to the music.

[a4eaudio]

I'm not sure, but I think:

Jeff Bagby's white paper and VituixCAD guide both recommend nearfield at about 1/4".
You need to run your nearfield measurements through a diffraction simulation to remove baffle step. Your farfield measurements would already reflect this, as they were measured in the actual cabinet on the actual baffle.
You do NOT need gating on nearfield (or at least it can be long, like 30 to 50 ms). You're a quarter of an inch away, no room reflections are making it to the microphone for quite a while relative to the primary signal.

[a4eaudio]

On the plus side, both the baffle step and gating are simply processing of the raw measurement. You shouldn't have to re-measure.

[jimbones]

all, Hold the phone! In prior posts I had asked about ports (proximity to cabinet etc and port length) Well I cut the port for one speaker and additional inch-1.5 inch so it gives me more room between the padded rear wall and the port. Today I was playing bass heavy material and in one speaker air was coming out of the port and on the other nothing. I am wondering it is being blocked. This coincidentally is the speaker I was making measurements on. I will go and cut the other port so the match and rerun the sweeps. Stay tuned (pun intended)