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amp for infiinity kappa 9

I looking for advice on which amp or amps to use. I'm in a transition from mid-FI to HI-FI. I want to build a system around the Infinity kappa 9s I just bought on e-bay for 800 dollars. I tried to drive the speakers on a yamaha m2 amp. No dice. It shuts down at moderate volume. Step 2 I tried an Adcom gfa 555. Cooked the amp in short time. I have heard that a tube pre amp is recommended because of the emit tweeters. I currently Use a Mcintosh MC2100. It will drive the speakers to its full power but falls short of what the speakers are capable of. Would another MC2100 work if i used the 2 for mono blocks 1 to each speaker or will I still come up short on power? The system I want to build will be very Basic. I have a Yamaha C2 pre-amp, dyno fm-3 tube tuner, Technics SM1200 tuntable, Nakamichi Dragon cassette deck, Akai GX 747 open reel tape deck,DBX 4bx dynamic range expander, and a Denon DCD 1500 cd player. I also have an ADC SS315 equalizer. Now I am aware that these are not the best componets to use but they are all that I have for now. Any and all advice on what to keep and what should go would be welcome. I listen to Blues and classic rock most of the time but sometimes classical and big band is a nice change. I dont even know how much I want to spend. I will just build the system slowly piece by piece and use some of what I have now. Most of this stuff was bought 20 years ago when I was in the service. Can anyone help this newbie out on my quest for HI-FI?
coman61
sean
6,231 posts
 
Given that this speaker dips to .8 of an ohm at appr 33 Hz and .9 of an ohm at appr 7.2 KHz, you need a MASSIVELY powerful amp that can deal with huge current demands at both ends of the audio spectrum simultaneously. With that in mind, i would suggest looking into a Sunfire Signature with what is called their "Apogee mod" from the factory. If interested in this modification, you need to speak to Robert in Sunfire's technical support department.

I would further comment that if you were to go with an amp of this calibre and power potential, you really need to run it on a dedicated AC circuit. This dedicated circuit should be capable of providing at least 20+ amps of current. After all, if you are going to be able to produce gobs of power and current from an amplifier, it is going to have to pull sizeable amounts of power from the wall.

In the long run, you may find that your "bargain of a buy" on these speakers really is no bargain at all. They are phenomenally demanding in terms of the support components and the AC that they require in order to work their best. As far as dynamic speakers go, they are one of a select handful that can qualify as the the poster child for "tough to drive" speaker loads. Sean
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sean
6,231 posts
 
I should have mentioned that this speaker stays below 3 ohms from 60 Hz and below. Given that you already need high levels of power to control a large woofer as it is, compounding that demand with a very low impedance at that point is pretty rough.

This speaker is also 3 ohms or less between 1.5 KHz and 4 KHz. There is a slight peak to 3.5 ohms at 4.5 KHz. Above 4.5 KHz, the impedance starts dropping rapidly and stays below 2 ohms up to beyond 20 KHz from that point.

Like i said, this is a VERY tough speaker to drive. The fact that it isn't all that efficient either is just more to deal with. Sean
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lneilb's avatar
lneilb
108 posts
 
One more bit of bad news: Infinity is not supporting these with replacement drivers any longer. On the plus side, the midrange performance is outstanding.
coman61 OP
26 posts
 
Well allrighty then!! I guess I will have seek out ampzilla to drive these bad boys. I'm not a quiter I will get the job done. Thanks for all the input. Stay tuned and I'll let you all know how this works out. Sean putting in a dedicated circuit will not be so bad because I'm remodeling my listening room. Thinking about getting a big Mcintosh. Anyone had any experence with the Bryston 4b? Also seen some good prices on aragon palladiums. If I find a good deal on a Threhold 500s maybe I'll give it a try. Thanks again everone.
sean
6,231 posts
 
I used a completely factory refurbished Bryston 4B on some speakers that are also low impedance and very insensitive. Not only did it not sound good, it was constantly going into clipping. I would highly recommend that you NOT use one of these amps.

There are a few guys that i've talked to from this and other forums that have Kappa 9's. Wanna guess which amp(s) they are using??? I already suggested it above. Sean
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