Jims 3 way speaker build

[jimbones]

Box tuning also looks to be around 38-39Hz.

I wouldn't adjust this just yet as you will need to add more stuffing to deal with box resonances. However, in a target 70L enclosure with an SB34NRXL performing to spec, you are likely not getting the expected magnitude response - bit of a hump up at 50hz and sharper roll off (bit of a knee) - could give you some undesirable boom - or it could be insignificant.

F3 is negligibly different but if you're aiming for some accuracy here your port length will need some fine tuning - just do it after all internal materials are in place and measure both impedance of the woofer and frequency response, nearfield, of both woofer and port (combine appropriately), just so you can see both where the tuning is and how its impacting the bass performance before tuning port length.

I agree DeZZar thats why I did not glue the port. I will try the damping and remeasure and report back.

[jimbones]

OK so I added insulation/padding/polyfill in the cabinet and didnt really help. Not sure what I am chasing...

[Billet]

How do they sound when playing music?

[jimbones]

I have not tried because I dont have a well designed crossover yet. I do have a XO that was designed in Xsim using manufacturers data. I understand the need to make measurements on the actual baffle so that is where I am at now. I COULD play the speakers usig the existing XO. It may not be great but may be close. What do you think??

[Billet]

I try to listen to music at every step of the process, if possible. It can be very educational.

[gregrueff]

A cursory glance suggests you have a leak around the port (it is not fully sealed) and the damping has reduced your box resonances.

When you have a leak, the impedance flattens out like that and does weird things.

Your box resonance has dropped from a 5 ohm peak to a 1 ohm anomaly at 150 Hz. It looks like the 650 Hz mode has been minimally affected.
Maybe the 650 Hz mode is the front-to-back cabinet dimension?

You can try maximally stuffing the box to see what it takes to completely kill them. I have measured in the past a slight increase in HD related to box resonances like these, but I’m sure you’ve tamed them enough to be inaudible 🤷‍♂️

Cheers!

[a4eaudio]

A cursory glance suggests you have a leak around the port (it is not fully sealed) and the damping has reduced your box resonances.

When you have a leak, the impedance flattens out like that and does weird things.

I don't remember the details but I had this happen recently. The leaks were small but made a big difference. It addition to the port (as greg mentions above), make sure you have good gasket seals on all of the other drivers, all of your screw holes have screws in them, etc.

[rpb]

I'd suggest plugging the port, and see what effect that has. (I've never measured the impedance, so I have no experience on this. )

[jimbones]

I'd suggest plugging the port, and see what effect that has. (I've never measured the impedance, so I have no experience on this. )

good suggestion, will do, and thank you very much

[Wolf]

Is the mid chamber damped on the outside top and bottom? I don't see any in the images. The 650Hz could also be the height from chamber to floor.
13560/distance = freq, or 13560/freq = distance; without factoring in quarter waves.
650Hz = 20.8", which looks pretty close to your issue.

Wolf

[jimbones]

OK so I have been delayed as I am waiting for damping material for the cabinet. While I am waiting I did have a couple of questions. I know it is nearly impossible to measure bass response in my room. I am crossing over my woofer to mid around 225hz. Instead of using my screwed up frd file should I use the manufacturers frd with my own generated frd of the mid and tweet on my baffle?

[Chris Roemer]

If crossing around 200Hz, your response is basically the "box response" as shown in any box simulator software (which doesn't account for room modes, of course). Most peeps who DO measure woofer .FRDs themselves "gate" (which limits the bottom end measurement below around 300Hz anyway), and then splice on the box-sim response below the 200-300Hz range.

[jimbones]

OK so I have been delayed as I am waiting for damping material for the cabinet. While I am waiting I did have a couple of questions. I know it is nearly impossible to measure bass response in my room. I am crossing over my woofer to mid around 225hz. Instead of using my screwed up frd file should I use the manufacturers frd with my own generated frd of the mid and tweet on my baffle?

[jimbones]

So just to get started I loaded up the zma as is and put in a quickie XO, and the impedance comes out very low. Doesn't sound right that it should be this low. Maybe I am doing something wrong?? 2.5 ohms??

[johnny5jz]

Post up your crossover schematic.

[jimbones]

Post up your crossover schematic.

This is very preliminary and I even take pause to post it as I just wanted to see what the system impedance would look like.

[rpb]

I 'm just speculating, but try increasing L2 and L3 by 60% or so.

[Chris Roemer]

3-ways are often plagued more with low-impedance than 2-ways.
Are they all 4ohm drivers? (From what I can tell (YOUR .ZMAs) they're all 8ohm? A "typical" 8ohm 3-way might "min out" in the 5-6ohm range.)
Do you have a lot of overlap (caused by shallow slopes, AND a narrow mid band-pass - 3 octaves (or more) is best)?
It SEEMS (to me) that you might get a higher Z using a bandpass (mid) topology using a series cap, THEN your series coil, and THEN the shunts (to gnd)...
Not sure why this is, but I do think it's true.

Also, don't you need any attenuation on the tweet and mid? Series resistance will help hold your Z up (aren't you using any baffle-step?).