Can I use PVC end cap for mid pod

J

jrwalte

New member
My mids are currently installed in my kicks. I have bad dips between 500-800 (REW response curve attached). I suspect this is because of their location and want to move my mids to my a-pillars. But I have no idea how to fabricate and don't really want to deal with bondo/fiberglass. I currently have my tweets in a PVC end cap in my a-pillar and was thinking to do the same with the mids.

The hertz 700.3 mid has inner diameter of 2.91" and outer 3.45". I plan to use a 4" end cap and make a wood baffle to insert in the end cap and secure the speaker to it.

My main question is would the small space of the end cap be bad for the mid response? Should it be sealed or should it vent to behind the pillar trim through the lamp nipple used to mount it and route wiring? If I should vent, do you think the nipple is enough to vent or would a second one help?

The idea is to mount the mid where the tweeter currently is. Do you think i should then move the tweeter pod just above the mid or move it to the panel at the side mirrors?

Hertz 700.3 technical sheet:
https://www.hertzaudiovideo.com/wp-.../HERTZ_Mille-Legend_ML700_Tech_Sheet_16_A.pdf

Natural Left and Right response curve with no filter in the kickpanel:
View attachment 8748

Current Mid installation:
https://photos.app.goo.gl/Bmjk7vWtkUUQZFvG9

Current tweeter pod installation:
https://photos.app.goo.gl/gx8YbYG9yspUUM4YA
 
So is it fine if I had a larger pod? I could extend its length to increase the volume to whatever it would need to be.

Or are you saying it should never be in a pod sealed or venting through a metal tube.
 
I'd vent through the lamp nipple because it would be better than nothing. just make sure any sound exiting out through it is attenuated by wherever it exits into. And put polyfil in the endcap. Also experiment with ocf too if you have it since you'll be vented in a crude aperiodic way. Venting the back of a pvc endcap worked great for my gb25's so no reason it won't work great for your mids.
 
Thanks HB.

Can anyone help determine what a good volume size would be for this speaker? I'm wondering if it would make sense if I extended the length of the end cap.
 
Looking at the specs in the link you provided, I would guess it would need .75 - 1 liter. Model it like a sub, and see what you get.
 
See attached file which is for a nice alignment most consider a good q for dynamics and damping

the reason it wants quite a large enclosure is because it’s quite a high Q driver, it’s been designed with free air in mind like a lot of the hybrid audio drivers so I’d vent it into the a-pillar personally
 
Thanks

With about a 3.75 diameter that would be about a foot long tube for 2 liters. Not practical.

My thinking is to use a larger nipple to allow more air through. At least 1".
 
Been thinking about this and came up with another idea to vent the mid out of the cabin.

I plan to cut a hole in the metal at the a-pillar for the pipe (I figure between 1-1.5" - the largest size the end cap will allow me to fit). I will weld the pipe to the metal and seal the joint with butyl rope. Then pass the pipe through my trim to the pod and seal the pod. I figure this will be better because 1) I won't have a backwave bouncing between my trim and down the side of my dash, leaking to the cabin and 2) the mount to the metal would be more sturdy than clamping it to the trim panel.

View attachment 8844
 
Hillbilly SQ said:
I'd vent through the lamp nipple because it would be better than nothing. just make sure any sound exiting out through it is attenuated by wherever it exits into. And put polyfil in the endcap. Also experiment with ocf too if you have it since you'll be vented in a crude aperiodic way. Venting the back of a pvc endcap worked great for my gb25's so no reason it won't work great for your mids.
Click to expand...

Its not better than nothing. By adding a very small vent, you just created a resonant mass of air, aka, a port. This will definitely cause fuckery in the frequency response
 
SkizeR said:
Its not better than nothing. By adding a very small vent, you just created a resonant mass of air, aka, a port. This will definitely cause fuckery in the frequency response
Click to expand...

Well, what I did with my endcaps didn't seem to cause any fuckery but it's also closer to aperiodic or IB than anything. It solved the problem I was having that was causing the gb25's to ring and not be happy crossed below 800;)And no one that has listened has mentioned any fuckery in the midrange. When tuning they didn't need anything drastic outside of a nudge here and there to flatten them out between 300 and 4000.
 
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