Replaced Adcom GFA555Mk2 with XPA-1's

[eric84405]

Bryan,
I would not be surprised to see your power conditioner limiting the current to the XPA-1's. That being said, those speakers are a difficult load to drive. Perhaps it could be caused by both variables combined although I've heard the XPA-1 will pretty much drive a dead short.

[bryanzim]

I'm not sure how the impedance curve looks after you changed out the woofers. By wiring the woofers in parallel I believe you're decreasing the resistance on the woofers making the require more current.

The Kappa9's use an LC filter network to perform the crossover at 80Hz and it is this tuned filter that causes the impedance dip. I couldn't see the curve at AudioKarma but have modeled the circuit myself with www.aade.com/ Filter Design tool. It is my belief that the original woofer's are about 4 ohm's so when wired in series they become 8 ohms. The replacement woofer's I put in are about 16 ohms in the range of 20-8Hz so when wired in parallel they become 8 ohms. And the impedance curves should remain the same.

How come you didn't just get them refoamed? The 12" Kappa woofers sound great and I wouldn't imagine replacing them with anything other than Kappa woofers.

I did buy the refoam kits, but I couldn't bring myself to just refoam them with another foam surround that would last 10 years and then have to do it again. I though about putting on rubber surrounds but then just decided to replace the woofers. I still have the original woofers and maybe one day I will refoam them; however I am extremely happy with the sound of the replacement.

How about some pics when you get a chance?

Pictures attached in 7-Zip file.

]I would not be surprised to see your power conditioner limiting the current to the XPA-1's.

I'm almost positive that this is what is happening. When funds permit I will upgrade to either a larger UPS or purchase another UPS to distribute the loads.

How are those Polydome K's holding up? I would try visiting audiokarma.org on the Infinity forum.

I never could register since I couldn't pass the secret question. ;D

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[aboroth00]

EEEK Those Polydomes aren't looking good... Are they still pliable? What I found best to do is to condition the domes with a rubber conditioner/cleaner to clear the residue and soften the domes as well as to protect it against UV and humidity.

I have done this on my 7K 6K but I have yet to try it out on my 9K's because they're still clear and supple. Pending how the domes do on the other Kappa's I wouldn't hesitate to try it out on my 9K.

[bryanzim]

My polydomes are still pliant even though they are cloudy. What is the rubber conditioner you use?

[aboroth00]

Mar 29, 2011 10:33:19 GMT -5 bryanzim said:

My polydomes are still pliant even though they are cloudy. What is the rubber conditioner you use?

I use meguiars rubber/vinyl cleaner/conditioner for cars. It seems to make the domes a little more transparent as well as making them more pliable. However, once they go down the path of cloudiness it seems their days are very limited.