Need help w/ kappa project

[Tulsajj]

Ok, I have built my single kappa pretty close to specs. I'm using an o audio 500 watt plate amp which I mounted in lower left corner. I was testing it out last night for the first time and it sounded good other except when I turned the gain more than half, it seemed like it was over working the speaker and just didn't sound good. I have the crossover set to 80hz the high pass set to 20hz, the phase and other adjustments set in the middle. I thought the kappa would be able to take a lot more power so I don't see how this would be overworking the speaker. Any ideas?

Then this morning I woke up and when I turned my receiver on, the plate amp didn't come on so I have an email into o audio for that...

 

[Matt34]

What's the gain set on your receiver? Have you level matched it to you mains yet?

 

[FNG212]

I can only speculate but the internet is a great place for that: I dont know what the displacement of the amp is inside the box but if you didn't account for that, it may affect the acoustics of the box. Second: you may have a seal leak somewhere letting air in/out. WmAx or Isiberian or a Red Name can probably tell you better.

Always a chance the amp is defective.

 

[Tulsajj]

No, I have matched anything yet. This evening once or if I get the amp to power on I will run the receiver macc or whatever it is called.. I may have a air leak where the amp screws in since I only used 4 screws (corners), there is four more screw holes - would this have made a difference?

I don't think the amp is taking up that much room in the box, so I wouldn't think that is it..

 

[Haoleb]

You need to properly seal in the amp and the driver. Use a gasket material if the amp did not come with one. The gasket that comes with the driver is insufficient in my opinion, and use all the screws you can... Not to say thats what your problem is but its certainly something you should do either way.

 

[Tulsajj]

Ok, hopefully the amp not being sealed is the problem. I did notice the middle of the amp didn't seem sealed very well but I was just in a hurry and hooked it up to listen and make sure every thing works before I round over the edges and paint.

The amp not coming on is puzzling me; don't see what could happen over night. But I will research that further when I get home...

 

[lsiberian]

Ok, I have built my single kappa pretty close to specs. I'm using an o audio 500 watt plate amp which I mounted in lower left corner. I was testing it out last night for the first time and it sounded good other except when I turned the gain more than half, it seemed like it was over working the speaker and just didn't sound good. I have the crossover set to 80hz the high pass set to 20hz, the phase and other adjustments set in the middle. I thought the kappa would be able to take a lot more power so I don't see how this would be overworking the speaker. Any ideas?

Then this morning I woke up and when I turned my receiver on, the plate amp didn't come on so I have an email into o audio for that...

Is this the Perfect VQ or 12.1?

How are you testing it?

Is your sub maxed on the receiver? Are you using the EQ on the sub at all?

Try putting the highpass higher. You may be very sensitive to distortion like me. Let's hope not.

 

[Tulsajj]

I'm using a 12vq, I'm not really testing it, just hooking it up make sure everything sound good before I spent the all the time to make it look pretty. No, I didn't have the sub maxed on the receiver had it +2. I'm not really using it yet since I really don't know how to set the eq.

 

[WmAx]

The O Audio, at 450 watts, can't even come close to over-driving the Perfect driver. The amp will distort far before the driver will. You may have a defective amplifier. And also, as others pointed out, be sure to take care of all air leaks. Air leaks are a big deal on a ported system such as this and can make it perform radically different than intended.

-Chris

 

[lsiberian]

The O Audio, at 450 watts, can't even come close to over-driving the Perfect driver. The amp will distort far before the driver will. You may have a defective amplifier. And also, as others pointed out, be sure to take care of all air leaks. Air leaks are a big deal on a ported system such as this and can make it perform radically different than intended.

-Chris

Chris

It appears to exceed xmax at 400 watts in this model which is linked directly from the project's thread.
I've never modeled the perfect above 300 watts before exceeding xmax.

That being said I doubt the O-Audio is getting close to that level of power and would never run it that hot. It's a plate amp and it's possible that it just can't handle the Kappa running really high volumes. Seal it and make sure everything is ok first. Then try it.

 

[WmAx]

Chris

It appears to exceed xmax at 400 watts in this model which is linked directly from the project's thread.
I've never modeled the perfect above 300 watts before exceeding xmax.

That being said I doubt the O-Audio is getting close to that level of power and would never run it that hot. It's a plate amp and it's possible that it just can't handle the Kappa running really high volumes. Seal it and make sure everything is ok first. Then try it.

Linear x-max is one thing; but this driver will not hit mechanical limits until around 23-24mm one way. In addition, the excursion zone is I power a couple of 10" perfects with 650 RMS each and the amp clips first before the drivers are in danger.

-Chris

 

[Tulsajj]

Just an update.. I checked my plate amp last night when I got home to see why it was not coming on and it had a blown fuse - I have no idea why since it was working fine the night before. Went to Lowes to get some replacement fuses and it blew them as soon as I turned it on, but now I'm starting to think the replacement fuses were to small. I have an email to OAudio to see if they will just send me an replacement amp. I will provide an update once I get this taken care of..

 

[lsiberian]

Just an update.. I checked my plate amp last night when I got home to see why it was not coming on and it had a blown fuse - I have no idea why since it was working fine the night before. Went to Lowes to get some replacement fuses and it blew them as soon as I turned it on, but now I'm starting to think the replacement fuses were to small. I have an email to OAudio to see if they will just send me an replacement amp. I will provide an update once I get this taken care of..

You have a bad amp

 

[Tulsajj]

This is the email I received from OAudio:

"The failure symptoms that you describe are usually experienced by folks who mis-wire a dual-voice coil driver; or, very very rarely, have a single-voice coil driver that the vendor claims is "4 ohms" when it actually is significantly lower.

I took a look at the owner's manual for the driver you are using - http://manuals.harman.com/INF/CAR/Owner's Manual/Perfect VQ OM FINAL (Revised 12-2-02).pdf - provided that your driver is in good condition, everything should be ok regarding the load that is being presented to the driver. Your driver is SVC and Re is 3.42ohms which shouldn't be a problem for the amplifier.

As a sanity check, could you measure the DC resistance of the voice coil? I want to rule out the driver as a possible cause for failure before sending a warranty replacement; also, want to make sure that a replacement amp will solve the problem.

Thanks!

Eric Oiesen
O Audio"

Can you help me decipher this..

I know this is not a dual voice, 1. it is labeled as 12vq and 2. This only 2 wire hookups on speaker, doesn't dual voice coil have 4?

How do I measure the dc resistance of the voice coil?

Should I go to radio shack and see if I can find the exact size of fuse and just try to replace it again or would you consider this amp faulty for the fuse blowing overnight when it was not in use in the first place?

Thanks..

 

[lsiberian]

This is the email I received from OAudio:

"The failure symptoms that you describe are usually experienced by folks who mis-wire a dual-voice coil driver; or, very very rarely, have a single-voice coil driver that the vendor claims is "4 ohms" when it actually is significantly lower.

I took a look at the owner's manual for the driver you are using - http://manuals.harman.com/INF/CAR/Owner's Manual/Perfect VQ OM FINAL (Revised 12-2-02).pdf - provided that your driver is in good condition, everything should be ok regarding the load that is being presented to the driver. Your driver is SVC and Re is 3.42ohms which shouldn't be a problem for the amplifier.

As a sanity check, could you measure the DC resistance of the voice coil? I want to rule out the driver as a possible cause for failure before sending a warranty replacement; also, want to make sure that a replacement amp will solve the problem.

Thanks!

Eric Oiesen
O Audio"

Can you help me decipher this..

I know this is not a dual voice, 1. it is labeled as 12vq and 2. This only 2 wire hookups on speaker, doesn't dual voice coil have 4?

How do I measure the dc resistance of the voice coil?

Should I go to radio shack and see if I can find the exact size of fuse and just try to replace it again or would you consider this amp faulty for the fuse blowing overnight when it was not in use in the first place?

Thanks..

an ohmmeter is the best tool to measure resistance with.

 

[Tulsajj]

I measured w/ a multimeter and it was bouncing back from 3.4 to 3.5 so I guess that is where it should be. How low would be to low for this amp to handle? So now I guess I just have to wait till I can get them to ship me another amp.

 

[lsiberian]

I measured w/ a multimeter and it was bouncing back from 3.4 to 3.5 so I guess that is where it should be. How low would be to low for this amp to handle? So now I guess I just have to wait till I can get them to ship me another amp.

You got it.

 

[WmAx]

I measured w/ a multimeter and it was bouncing back from 3.4 to 3.5 so I guess that is where it should be. How low would be to low for this amp to handle? So now I guess I just have to wait till I can get them to ship me another amp.

2.3 Ohms DC (Re) is probably where the amp would start having problems. This would indicate approximately 3 Ohms nominal load. 2.9-3 Ohms is a typical reading for 4 Ohm Nominal drivers. The Kappa VQ appears to actually be more like 4.3-.4.5 Ohms nominal; which makes it a super easy load for '4 Ohm' stable amps. This is not surprising, Harman Kardon likes to make sure speakers are easily driven by just about any amplifier.

-Chris

 

[Tulsajj]

Ok, after getting the replacement amp I figured out what was the problem - it was not sealed up properly. I had massive air leaks around the plate amp, even w/ all the screws in place I'm still having slight air leaks. I'm considering countersinking the amp 1/8" so it is flush and using some type of foam or silicon to help seal it better.

It sounds good and it is loud, but I think I was expecting it to be a little louder by no means is the water in my sink moving like Haleb's or my neighbors running over to tell me their house is shaking. I think that has to do w/ my amp pushing less watts, I only have one kappa, and my room is larger with more openings to the house. I have the gain on the amp 1/2 way then using the receiver to adjust, it is hard to tell how loud it can go before doing damage to amp... I would like to figure what my boundaries are.

With the OAudio amp, what do they mean by boost? Is boost bad? If I switch my high pass to 25hz would that mean less boost which would make it louder?

 

[Haoleb]

I would use the gasket sealer tape I reccomend for your driver and amplifier if its not too big. There are also smaller types.

Also keep in mind I have one amp per sub which bridged into 4 ohms is rated at 1.4KW, So I have considerably more power. And i have had the clip lights going before...