Haoleb's Kappa Perfect 12vq MidQ Build Thread

[WmAx]

I did carefully outline the basis for this design (avaserfi's original build) and specify the specific acoustical treatments in the interior and choose an extraordinarily linear driver so that the end result would be an absolute transparent LF device with signficant linear dynamic range abilities. Though, I am kind of surprised that Axiom did not put more effort into their design. I bet, also, if you use a shallower crossover slope(12db for example) or cross higher, that the Kappa sub will also sound far better in this capacity, as this was another one of the design objectives. The only potential issue for higher or shallower slope crossover is port resonance, which is easily counter-acted using the DCX. You would measure the port output with the mic placed closely to the port(1") and then program in a notch filter to cancel the peak. Again, this is likely only an issue if you use a shallower slope or higher crossover frequency.

-Chris

 

[mike c]

AH reviewed the EP500 and found that it was tuned to 25hz.

for it to have f3 extension to 18hz, it had to have EQ boosts BELOW tuning which would result in THD

 

[Haoleb]

While playing test tones I discovered that one of my VQ drivers has a faint buzzing sound at certain low frequencies, This is only audible when I am right up near the driver and is definetly coming from the cone vs something inside vibrating or loose screws etc. I took the driver out and did not find anything out of the ordinary, I made sure nothing came loose or that there was nothing inside the center pole area (those inserts do NOT come back out easily!).

I think the VC leads where they attach to the cone may be the culprit as it does sound very similar to how the woofers on my M80's sound when I play something too loud and the VC leads vibrate against the cone. Is there some type of adhesive that I could use to just put a dab on the leads to see if that stops it? Hot glue, Gorilla glue? If there is nothing I can try gluing them to the cone with safely I wont attempt it as it is not audible with normal program material, even up near the cone. Playing test tones really brings out flaws very easily I have found. If I ever were to build speakers for a living I would definetly make it mandatory to sweep through the freq range to check for vibrations and such.

 

[Djizasse]

duct tape?

 

[Haoleb]

Just remembered that I had something made by 3M called Scotchkote. its originally designed for coating splices in wires for waterproofing, But its actually handy for much more than that. I actually got it for using on my scope mounts on my Air rifle to stop scope creep. I'll see if that stops the buzzing once it hardens.

 

[Alex2507]

Is there some type of adhesive that I could use to just put a dab on the leads to see if that stops it?

http://www.mgchemicals.com/products/8337.html

 

[TLS Guy]

While playing test tones I discovered that one of my VQ drivers has a faint buzzing sound at certain low frequencies, This is only audible when I am right up near the driver and is definetly coming from the cone vs something inside vibrating or loose screws etc. I took the driver out and did not find anything out of the ordinary, I made sure nothing came loose or that there was nothing inside the center pole area (those inserts do NOT come back out easily!).

I think the VC leads where they attach to the cone may be the culprit as it does sound very similar to how the woofers on my M80's sound when I play something too loud and the VC leads vibrate against the cone. Is there some type of adhesive that I could use to just put a dab on the leads to see if that stops it? Hot glue, Gorilla glue? If there is nothing I can try gluing them to the cone with safely I wont attempt it as it is not audible with normal program material, even up near the cone. Playing test tones really brings out flaws very easily I have found. If I ever were to build speakers for a living I would definetly make it mandatory to sweep through the freq range to check for vibrations and such.

I think you have a faulty driver. The most likely fault is a loose winding on the voice coil. I would return the driver and exchange it for a new one.

 

[Haoleb]

I think you have a faulty driver. The most likely fault is a loose winding on the voice coil. I would return the driver and exchange it for a new one.

I think you may be right. Putting the scotchkote on the leads there did not fix the problem as I had hoped. Its such a small issue that I dont think it would even be worth it to go through the cost and hassle of getting a replacement. Although Now it is going to bug me knowing its there.

 

[TLS Guy]

I think you may be right. Putting the scotchkote on the leads there did not fix the problem as I had hoped. Its such a small issue that I dont think it would even be worth it to go through the cost and hassle of getting a replacement. Although Now it is going to bug me knowing its there.

The problem is that if my guess is right, then this will get worse. Sometimes the coil suddenly unravels. In new speakers this problem is one of the commoner production faults. May advice is to change it before the warranty expires.

 

[Haoleb]

The problem is that if my guess is right, then this will get worse. Sometimes the coil suddenly unravels. In new speakers this problem is one of the commoner production faults. May advice is to change it before the warranty expires.

That would definetly be a bad thing. I have a 1 year warranty for them so if it does get worse I will see about getting a replacement. The biggest problem is that it would cost nearly as much to pay to send it back, and then have a new one sent to me as it would to just buy a brand new one. The costs of shipping affects EVERYTHING when you live here

 

[Haoleb]

Its already gotten worse...

I have contacted Sonic Electronix where I ordered them from. I think its going to end up costing me a good 100 bucks to get a replacement... And thats if they dont notice the scotchkote I put on there

Seems like I have the worst damn luck when it comes to speakers. I suppose there is a bright side. Since I built two of them I will still have one to use

 

[Haoleb]

Well Sonic Electronix will not cover any of the shipping charges. Basically its like 65 bucks to ship this thing. Each way. So I wont be returning it afterall. Smart policy on their part Sucks for me. The rattling sound actually isint as bad as I thought its just certain frequencies. Although... I could not help myself today.. After a few beers mind you and decided I needed to fire up the signal generator on REW and see what 20hz could do to my drywall. Here is a short video of the water in my sink. I really started laughing when I walked over and saw it like that. I wasnt laughing quite as much when I stuck my head in the ports of the subs and that one with the rattling sound smelled a little.. Hot perhaps playing 20hz tones for more than a few seconds at a time at a reasonable volume isint such a great idea. The other driver smelled normal though. I think i'm going to end up just buying a new driver for that one sub and use this one in my truck.

Anyway, here's the video. I wanted to get more of the rest of the stuff rattling around but didnt want to see how long that driver could handle the pressure. The quality is crappy and so is the microphone on the camera... Oh and dont mind my sink full of dirty dishes. Im going to wash them. soon.

 

[Haoleb]

Alright, Ordered another driver I dont know if it has anything to do with that driver already having a problem but it definetly smells like it got too hot when I was screwing around with that 20hz stuff Already took the driver out and installed it into my tiny box to use in my truck. It still seems to work just fine but eek!! I wont be doing that again.

I cant imagine its that the driver just could not handle the power because the other one doesnt smell like it got hot at all.

Lesson learned. Dont try and fix something yourself when its still under warranty. Hence not being able to send it to infinity because of the scotchkote. And buying from non authorized places is always a risk!

Oh yeah, And dont play 20hz sine waves at 112db for a minute or two straight.

 

[Djizasse]

Didn't your mom told you:
"Don't drink and drive"?

 

[WmAx]

Well Sonic Electronix will not cover any of the shipping charges. Basically its like 65 bucks to ship this thing. Each way. So I wont be returning it afterall. Smart policy on their part Sucks for me. The rattling sound actually isint as bad as I thought its just certain frequencies. Although... I could not help myself today.. After a few beers mind you and decided I needed to fire up the signal generator on REW and see what 20hz could do to my drywall. Here is a short video of the water in my sink. I really started laughing when I walked over and saw it like that. I wasnt laughing quite as much when I stuck my head in the ports of the subs and that one with the rattling sound smelled a little.. Hot perhaps playing 20hz tones for more than a few seconds at a time at a reasonable volume isint such a great idea. The other driver smelled normal though. I think i'm going to end up just buying a new driver for that one sub and use this one in my truck.

Anyway, here's the video. I wanted to get more of the rest of the stuff rattling around but didnt want to see how long that driver could handle the pressure. The quality is crappy and so is the microphone on the camera... Oh and dont mind my sink full of dirty dishes. Im going to wash them. soon.

A continuous sine wave is far more strenuous than music. You can safely use well over 1000 watts of music program, for example, but if you applied that as a continuous sine wave, you would most likely fry the voice coil after applying the signal for more than a few seconds.

-Chris

 

[GTHill]

I have to say that the water in the sink was quite incredible! Nice of you to sacrifice a driver in the name of YouTube.

Gene

 

[Haoleb]

I have the chance to pick up a pair of QSC RMX 1450 amps locally along with some other items for pretty cheap. Infact I could sell my EP2500 at a loss, Along with some of the other things that come with the amps and probably come out even if not ahead. Would it be worth it to get those amps and bridge them one for each sub?

 

[mike c]

the Behringer EP2500 is the imitation of the QSC RMX 2450

but you WILL have more power PER sub if you use one 1450 for each kappa. (though i'm not sure if that's necessary)

perhaps build two more kappa subs?

 

[Haoleb]

but you WILL have more power PER sub if you use one 1450 for each kappa. (though i'm not sure if that's necessary)

Arrggh Arrghhh Arrgghhhhh Powerrrrrrr!

Expect to see my EP2500 for sale in the coming days as hopefully tomorrow I shall take delivery of two Minty QSC RMX 1450's, A minty Parasound Zpre2 and some speaker selector thing.

 

[mike c]

personally, i'd keep the Behringer EP2500 ... it's still THE bang for the buck amp for ANY subwoofer or any speaker you desire.