Sexual intercorsa...

[dumdum]

It’s going to a battle of phase issues and reflections... so far I have tried the first position and I have the responses and the phase plots... as per usual I have a lovely dip around 850-1k which is the first reflection from the screen and the side window...

I think it’s going to be (as is usual in cars) making the best of the environment we have

currently I have the tweeters as high as they can pretty much go while staying on the baffle on little birch ply steps with the mid 15mm from the bottom of the enclosure... both drivers are on axis with there respective headrest pretty much, it makes the timing of the mid and tweeter on the drivers side approx the same... the tweeter was getting reflection issues to the drivers side window, moving it up and almost behind the pillar to the side window first reflection point

using a combination of all pass filters and normal eq and delay I have been able to match the two sides phase/time plots and got them to pretty much be in phase from start to finish (at most 45 degrees out for narrow bands apart from the big phase ‘flip’ I have due to the reflections

to check it was a side window reflection I added a technical cardboard box and a quick smaart read (with the tweeters off I should add) and the dip came right back up...

There is a pic of the mid low and the tweeter at the very top as high as the 40mm rule will allow... it’s close... but an inch or a mile!

[nadams5755]

i have a 1khz (and its octaves) phase issue on my left midrange driver that's alleviated if i put like a 4" wide strip of felt next to the driver on the side glass. the behavior presents itself as upper midrange pulling left. it's most apparent in LC and RC in the upper midrange.

i could play with angling the midrange differently but it'll probably just change the frequency of the phase issue.

[dumdum]

i have a 1khz (and its octaves) phase issue on my left midrange driver that's alleviated if i put like a 4" wide strip of felt next to the driver on the side glass. the behavior presents itself as upper midrange pulling left. it's most apparent in LC and RC in the upper midrange.

i could play with angling the midrange differently but it'll probably just change the frequency of the phase issue.

unless it’s an 8” midrange angling it won’t do much, it will be on I directional at 1khz

[geolemon]

I'm not sure this will help either one of you, but figured it wouldn't hurt.

On my '95 Civic (which I still own! ), I had these factory door tweeter locations that I wanted to make work. I wasn't facing a phase issue, but I did need to control the sound energy because that near-side tweeter was way too close, making the difference in pathlengths to your head very different in length, which just totally ruined the imaging.

I curved these out of simple plexiglass as an experiment - and to my pleasant surprise, they worked great.


You can't really see, but if I were sitting in my left side seat and the door were closed, the plastic shield is just small enough that I do get direct sound off at least half the dome - more like 3/4. Basically, I have a direct path to the tweeter.
But if I'm sitting on this right side of the car with the door closed, the tweeter is entirely blocked to my head. I can see the tweeter only through the plexiglass shield. So essentially, the direct path is blocked and the next most direct path has to reflect off the windshield, which I believe is what the original engineers were trying to do based on how the factory tweeters are aimed that way. I can't necessarily validate the theory of reflection, but if it's simply attenuation on each direct-pathlength side - well, either way, it works.

It popped into my head, because of the discussion of that large woofer. On those, whizzer cones and phase plugs are often used to break up off-axis cancellation - and both more or less operate on the same principle as what I was doing with my tweeter - block the sound energy from being able to travel across the cone when listening off-axis, to prevent those different-length pathlength distances (the near side of the speaker to your ear, vs the far side of the speaker to your ear). You can't add a phase plug or even a whizzer cone to an existing speaker (although I can't say I've ever tried - a paper whizzer shaped like a Dixie cup would probably only shift the Fs a bit, although you would need to ensure you used paper that was rigid enough not to cause other resonances), but it makes me wonder about trying little shields outside to try to block direct sound energy, or like you said - you can try to add some sound absorbing material.

So I don't know if that's helpful to either of you, to try to manipulate or avoid reflections.

[dumdum]

Some sort of waveguide has crossed my mind over a 5” mid, if I could get the 5” in the small quarter window and effectively make an artificial first reflection that would likely make a nice job of the front stage midrange I think, that’s this weekends try out I think

[dumdum]

So I’ve moved the mids back up as lower made the 900hz dip a lot worse, hopefully now the dip will be more spread out and less harsh in the one spot, I also have a few other tricks up my sleeve to see if I can’t correct the response somewhat... more on that at a later date, for now I will focus on eqing the response and then correcting the phase of each side so they both match exceptionally well and gove the stage it’s 3D and body which phase can give

so today’s job was more superglue, cardboard and hot glue which is excellent for a none permenant job of making an enclosure that’s easy to swap angles and baffle heights on

a couple of pics as I don’t have so many for now, the tweeters are staying at the top (I will also try under the mids after a week or so of listening)

the angle is at the ears, and approx 4-5” inside the headrest inner edge, basically the drivers side is aimed roughly at my left ear when I’m sat in the drivers side seat, the passenger side mirrors it using my laser aiming tool for the 6” baffles, so slightly upwards and while the passenger side is a little off axis I can level the image with eq on the top end, it’s only approx 3db I’d guess at 2500hz but measurements will tell the tale once I’ve played tomorrow

[nadams5755]

played around with an all-pass filter at that drop-out?

[dumdum]

played around with an all-pass filter at that drop-out?

An all pass won’t ever correct a big phase related dip, an all pass will only adjust phase in relation to another driver, it won’t help a phase related dip that is caused with a single driver playing, what I can do is play with a second driver down the length of the car and play that in phase with the left driver which has the dip but from the back of the car which is the point where the reflection happens and therefore the left mids phase becomes out of phase... if the mid as the back of the car is in phase with the left mid and tightly bandpassed it should then cancel out the wave down the car and combined with the reflection as or subtract nothing at the listening position... it’s an idea I will give some attention to and play with soon

[dumdum]

So due to erins review of its bigger 17cm brother and not needing anything that’s not rolled off below 160 I have gone ahead and ordered the sb acoustics ceramic 15cm driver the excellent pistonic behaviour of the mid should make it a very low distortion candidate but without the soft cone satori breakup ��

also as I have saved budget with those I have decided to up my tweeter game to a bliesma beryllium tweeter t25b-6 which by all accounts and reviews is awesome!! It also means I am only 120 euros more expensive than the current satori 16cm and scan 602000 and should now have treble to die for! Win win as I can step the iPad down to a 64gb to save some or even use my iPad mini 2 if it came to it but I think I should be ok with the mini 5 256gb still for now...

if push came to shove I could also swap to my workshop dsp mini and bin the rear sub off as I don’t need it for competition and save 150 euros that way... lots of wiggle room if needed to keep it under 4000 euros

[preston]

I just put a pair of Bliesma T25-6b in my new install. I won't do audiophool jargon, but it was a small but worthwhile upgrade when I first fired them up from the Scan speak 6020 silk domes thad had been running, and then over the next few days they seemed to "break in" and started sounding more fantastic each night during my listening sessions. Running them more or less on axis in the pillars from 2800Hz up. They look mint too.