Adelphos/Kairos port tuning & cab lining question from a total noob

[luxrising]

Hello All,
I'll soon be ordering the Bagby Adelphos (a variant of the Kairos) kit from Meniscus and I have a few questions that I'd like some clarity on before ordering.
It appears the kit comes with a 2" diameter cardboard port with a single external flared end. Unless not recommended, I'd prefer to substitute the stock port with a 2" precision port. Seeing as the precision port has flares at both ends and a different (larger) external flare profile, do I need to alter the overall length of the port to maintain the specified tuning? If yes, what would the new port length be?
I also see that the kit comes with Dacron damping to be placed freely inside the cabinet. Would it be advisable to line the cabinet walls with acoustic foam (or similar) in addition to the Dacron in the vented version of this 15x11.5x8.5 cab? If yes, suggestions for material and installation would be very much appreciated!
Thanks in advance for any help! I'm a decent woodworker with access to a full wood shop so cabinet construction is fairly straightforward for me but I'm entirely new to speaker design. I'm trying my best and pouring over everything I can but there is a ton to learn!
Best,
Derek

 

[Inductor]

Ok, just ask because there are members that master certain areas better.
In relation to the port, what is important is the inside diameter being the same, from there on you measure the length from middle of the bents so to say (read flares). This will give you the same tuning. The only difference is that you have less port noise and can use more power to the threshold of the air speed.

Second question, maybe someone can answer better, but don't use more than recommended Dacron damping or other type, or your speaker will can change tuning and in the end it can also be choked, like having a very low tuning and not enough output @LF. Reflex speakers need to have moderation in the placement of the acoustic stuff that is there maybe for two reasons, one the tuning and another the reflection of the sound trough the diaphragm and port that you don't want so this one usually is in the back panel and the former is related in the exactly amount to damp the speaker output and pretended behavior in low frequency.

 

[LineSource]

The initial portion of the flare wall functions slightly like a pipe, so sims show a shorter pipe length when flared ends are added.

WinISD: Satori MW16P-8
0.782cuft .... 35Hz Tuning

Two FREE ends
2" dia........7.57" long............894 Hz resonance

One Flanged end
2" dia........7.35" long............920 Hz resonance

Two Flanged end
2" dia........7.10" long.............952 Hz resonance
=======
Changing stuffing will affect sound and bass tuning.

A SEALED BOX PRODUCES SUPERIOR QUALITY SOUND!
Faster and more consistent transients.
Reduced bass phase shift.
Freedom from port 'leakage', resonances, and huffing.

MAYBE...Sketch out construction plans for converting to sealed plus woofer.

 

[system7]

As ever, it's a homework question:

SB Acoustics :: 6 1/2'' SATORI MW16R - OFF

That is a reflex driver. So it gets a tube.

The Adelphos is the flat baffle version of the Satori design:
Adelphos / Pair

You can improve cabinets with panel damping by sticking rubbery stuff to the side and top panels:
http://www.diyaudio.com/forums/multi-way/223174-interesting-read-i-found-lossy-cabinet-designs-harbeth.html#post3234256

Volume damping is all about the fluffy lighter stuff. TBH, it only does something above 3kHz. With reflex, eggcrate lining foam is a good thing too. Works much the same.

I always think it's good to add some shunt resistance to the tweeter. IDK if Jeff Bagby has done this, but a 22R tweeter shunt is a good thing IMO. Makes the amp more comfortable at high frequency. So sounds better, IMO.

 

[luxrising]

Thanks for the input guys. I'm planning on using a port, just still don't know if a larger flared external port end and an internal flare changes the tube length and if so, how much. Cabinet lining sounds easy enough, I'll do some more homework and pick a suitable material. System7, tweaking a crossover to achieve a desired effect is definitely beyond me at this point and I trust JB has the edge on me here so I'll stick with his design!

 

[Inductor]

Thanks for the input guys. I'm planning on using a port, just still don't know if a larger flared external port end and an internal flare changes the tube length and if so, how much.
...

As I said in the second post, short answer is no. If the diam. internal and lenght is the same.

Let's say you have two 3" diam. ports, the external diameter or thickness doesn't change tuning (). Now...it might change the internal volume or not. Let's say you use wood or a very thick material, then total net volume is less and changes alignment. Provide more volume then. That's the Vb of the speaker.

Also if you use a 4" port internal (diam) instead, it needs addiction in length. That's the Fb of the speaker. Have fun

 

[luxrising]

Thanks inductor, I like short answers!

 

[jReave]

One thing you can do is use the flared end inside the speaker and construct a flare for the other end by routing a roundover around the opening you cut in your wood. This is a very common practice.

 

[luxrising]

jReave, well that's seems so obvious now that it's been pointed out to me! Seems easy enough and I like the idea, think I'll give it a try.
Thanks for the suggestion!