Khanspire planning

[Eldiabolo13]

Hello Together

I would like to build the Khanspire. Since I want to use this also for listening to music, I prefer the ported version.
I ask myself now only the question of whether I install the bass reflex port in the back or as a downfire as in the Statements. In my room the speakers are quite close to the wall.

What would you recommend?

[JonMarsh]

You know what they say... it all depends. Ports can be boundary loaded into a plane such as a wall or floor, but the distance has to be taken into account and it changes the tuning. If you are at least 150 to 200% of the port diameter away from the boundary, then no changes are needed. There are speakers like the Warfdale Reva 2 which actually use a close mounted boundary and reduce the length of the port.

So, presuming you can meet those requirements, it's up to your personal preference. If either your floor or wall are prone to flexing, that might be something to take into account, as then they may reduce some frequencies and amplify others in the ported range. A floor loaded port may have less time delay difference from the front of the woofer, and may give you a small advantage in overall integration. But the back loaded might be easier to build...

Don't forget to use flares on the port.

[Eldiabolo13]

thanks if I understand correctly then for example with a 100 mm (sorry I'm European guy) port the distance to the wall or floot should be between 150 to 200 mm.
Is this the reason why the statements of Jim Holtz which have a floor loaded port, the distance from the port to the floor with the 9" hole and the spikes extended?

[---k---]

Hello,
Great to see another person building the Khanspires. I'm stilling enjoying mine. Every Friday and Saturday is family movie night, and I'm never not impressed.

I think Jon answered the question with the best rules of thumb. More space around the port the better, so it performs as intended.

The 9" your talking about, I believe is shown in this figure http://www.speakerdesignworks.com/St...ocadlayout.pdf
from http://www.speakerdesignworks.com/Statements_2.html Jim states: "There is a 9" circle cut out of the bottom 3 panels to allow room for a 3" x 4" (plus flares) down firing port to breathe. I wanted a down firing port but a rear firing one could be installed more easily with out any performance penalty." So yes, just trying to make as much room around the port as possible.


Do you have an old pair of the RS28 tweeters? My understanding is they are no longer available, and I've been out of it for a while, but I thought the replacement RST28 was not a drop in replacement.

[Steve Manning]

Hello,
Great to see another person building the Khanspires. I'm stilling enjoying mine. Every Friday and Saturday is family movie night, and I'm never not impressed.

I think Jon answered the question with the best rules of thumb. More space around the port the better, so it performs as intended.

The 9" your talking about, I believe is shown in this figure http://www.speakerdesignworks.com/St...ocadlayout.pdf
from http://www.speakerdesignworks.com/Statements_2.html Jim states: "There is a 9" circle cut out of the bottom 3 panels to allow room for a 3" x 4" (plus flares) down firing port to breathe. I wanted a down firing port but a rear firing one could be installed more easily with out any performance penalty." So yes, just trying to make as much room around the port as possible.


Do you have an old pair of the RS28 tweeters? My understanding is they are no longer available, and I've been out of it for a while, but I thought the replacement RST28 was not a drop in replacement.

Your right about the RS28 Ryan ....we had a couple of designs we were working through based on that tweeter that are now sidelined.

[Eldiabolo13]

Do you have an old pair of the RS28 tweeters?

Yes Ryan, i´ll have a pair of the old RS28A and 3 Pair of the old RS28A-shielded Version.

[Eldiabolo13]

So I will build the Khanspire in the ported downfire variant just like the Statements. Since I do not get a 3 inch tube in the european area but the next possible 70 mm has, I will use a 100 mm tube.
If my calculations are correct, then the 100 mm diameter tube should be 204 mm long. I hope that is correct.

[Eldiabolo13]

I have now built a test box, ported with 105 liters volume and a 8.6 cm tube which is 14 cm long and attached to the back. Attached are the measured frequency responses of the individual frequency channels. For my taste, and this is also confirmed by the measurement, the tweeter is about 5 dB too loud. The two peaks at about 45 hz and 75 hz, as well as the valley at about 50 Hz are due to my room.

But I have from the sound impression the feeling that the fundamental tone is missing, I mean it is too little bass present.



I have now lowered the volume of the tweeter by about 4 db (series resistance 1.5 ohms, parallel resistance 5.6 ohms), now my Khanspire also sounds like a hi-fi speaker!

[technodanvan]

Interesting that the tweeter was so hot - this was with the standard crossover in place?

[Eldiabolo13]

Hi yes I have built the original crossover, only all the coils with European normalized values which differ but only in max 5%.

[technodanvan]

Well, as long as you got it sounding good that's all that matters. I hope they last you a long time!

[Eldiabolo13]

I have now changed the tweeter again, because I did not like the sound. The tweeter on the right side in the picture was in first, the left after and it's a difference like night and day.
I have also tested the shielded variant, sounds just as good as the left unshielded.

[technodanvan]

Pretty lucky you had enough R28s to swap in, I didn't realize there was that much variance in them. Were some used previously?