Bal Posted October 30, 2018 Posted October 30, 2018 Hi All, After 25 years of faithful service I have upgraded my speakers from a pair of old Infinity Reference Studio Monitors to a pair of vintage Infinity Kappa 9’s. I understand the Kappa 9’s are an “amp killer’ and I need to have high current amp/s preferably in a bi amp configuration as the Kappa’s drop down to below 1ohm at certain frequencies. The local hifi shop recomended a few options: 1) Two anthem MCA225’s (Approx $2,700 each) 2) Two Rotel RB1582’s (Approx $2,250 each) 3) One McIntosh MC302 (Approx $14,000) Option 3 is out my budget, which is about $5k. I am open to second hand options too. Any suggestions of what I should buy within my budget to bring the best out of these speakers? Thanks in advance for any help or advice. 1
Guest yamaha_man Posted October 30, 2018 Posted October 30, 2018 https://www.stereo.net.au/forums/topic/255100-withdrawn-or-relisted-fs-krell-kas-hifi-show-sale-price/?tab=comments#comment-3993355
Bal Posted October 30, 2018 Author Posted October 30, 2018 6 minutes ago, yamaha_man said: https://www.stereo.net.au/forums/topic/255100-withdrawn-or-relisted-fs-krell-kas-hifi-show-sale-price/?tab=comments#comment-3993355 How much?
Guest yamaha_man Posted October 30, 2018 Posted October 30, 2018 2 minutes ago, Bal said: How much? Sorry, just read that the Mcintosh were out of budget which means the Krell’s are too.
Pegasus Posted October 30, 2018 Posted October 30, 2018 Pass Labs X250.5. I've driven loads of .5ohm without a fuss. Probably just a little more than your budget, but not by a huge amount. 1
Zaphod Beeblebrox Posted October 30, 2018 Posted October 30, 2018 20 minutes ago, Bal said: Hi All, After 25 years of faithful service I have upgraded my speakers from a pair of old Infinity Reference Studio Monitors to a pair of vintage Infinity Kappa 9’s. I understand the Kappa 9’s are an “amp killer’ and I need to have high current amp/s preferably in a bi amp configuration as the Kappa’s drop down to below 1ohm at certain frequencies. The local hifi shop recomended a few options: 1) Two anthem MCA225’s (Approx $2,700 each) 2) Two Rotel RB1582’s (Approx $2,250 each) 3) One McIntosh MC302 (Approx $14,000) Option 3 is out my budget, which is about $5k. I am open to second hand options too. Any suggestions of what I should buy within my budget to bring the best out of these speakers? Thanks in advance for any help or advice. Options 1 & 2 would be pnly average choices and, if you are thinking of bridging those amps into the Kappa 9, then you have been badly advised. Neither amp should be operated in bridge mode into Kappa 9 speakers. As others have suggested a big ole' Krell will do the trick, as would an ME850, if you can find one. Note the impedance at the LF end and the HF end. An amplifier killer indeed. 1
Ittaku Posted October 30, 2018 Posted October 30, 2018 (edited) How about a Sanders Magtech? They can drive pretty much anything. http://sanderssoundsystems.com/products/amplifiers/magtech-amp $5500 USD new, they occasionally come up in classifieds. Edited October 30, 2018 by Ittaku 1
audible1 Posted October 31, 2018 Posted October 31, 2018 I'd get some parasound jc1s. I think someone has them on sna now. I had a pair of mc601s monos and I confidently say that the JC1s better them significantly in all respects. 1
VanArn Posted October 31, 2018 Posted October 31, 2018 (edited) Another option to consider if your present amplifier is otherwise satisfactory is to fit the D + S Tech Labs re-designed crossover network which overcomes the low impedance flaw of the existing xover. http://dstechlabs.com/ (Look at their eBay store on the site map ). Edited October 31, 2018 by VanArn How to find the xover 2
andyr Posted October 31, 2018 Posted October 31, 2018 2 hours ago, Bal said: Any suggestions of what I should buy within my budget to bring the best out of these speakers? See below! 20 minutes ago, VanArn said: Another option to consider if your present amplifier is otherwise satisfactory is to fit the D + S Tech Labs re-designed crossover network which overcomes the low impedance flaw of the existing xover. http://dstechlabs.com/ (Look at their eBay products , listing ). +10!! A much more sensible option. (If you can find the redesigned XO on their site, that is! ) Andy 1
Paul R Posted October 31, 2018 Posted October 31, 2018 A good but under rated amplifiet is made here in Melbourne by Arthur Rappos. The Elektra Reference HD puts out 200w into 8 ohms and lots more into 4 ohms.I have a single unit driving the Aurum Cantus New Grand Supreme (which need heaps of power to drive and control them) with no problems. You can start with a single stereo unit and upgrade later by buying another unit and running them as bridged monoblocks.The Elektra Reference HD is I think within your budget.Good luck with your quest.Paul 1
Zaphod Beeblebrox Posted October 31, 2018 Posted October 31, 2018 10 minutes ago, Paul R said: A good but under rated amplifiet is made here in Melbourne by Arthur Rappos. The Elektra Reference HD puts out 200w into 8 ohms and lots more into 4 ohms. I have a single unit driving the Aurum Cantus New Grand Supreme (which need heaps of power to drive and control them) with no problems. You can start with a single stereo unit and upgrade later by buying another unit and running them as bridged monoblocks. The Elektra Reference HD is I think within your budget. Good luck with your quest. Paul You need to ascertain the performance of the amp into TWO Ohms and, preferably, ONE Ohm. The Kappa 9 is an extremely difficult loudspeaker. Amps that are specified into a minimum 4 Ohm load need not apply. 2
georgehifi Posted October 31, 2018 Posted October 31, 2018 (edited) Here's the impedance graph pitty there's no -phase angle with it, would probably make it look twice as savage. Cheers George Edited October 31, 2018 by georgehifi 1
Ittaku Posted October 31, 2018 Posted October 31, 2018 34 minutes ago, Sir Sanders Zingmore said: Easy Yep this is exactly what I was recommending and would be perfect for these, and right within your budget. 2
t_mike Posted October 31, 2018 Posted October 31, 2018 Look in the classifieds, I'm pretty sure there is an ME 850 a page or 2 back. There was someone selling some early SGR monoblocks some time back. Not sure if they are anything like their current offerings, which are current driven amps which will certainly cope with the loads. 1
Bal Posted October 31, 2018 Author Posted October 31, 2018 Thanks so much for all the great responses. I realise I have a lot to learn and totally underestimated what sort of power (and cost) is required to make these speakers sing. I also now realise that I have never really heard the true potential of my old Reference Studio Monitors as I have never listened to them being driven by a high quality amp. I looked into the aftermarket crossovers being sold on ebay, but the feedback from the vintage Infinity crowd wasn’t good. Off the back of this feedback I threw out a lifeline and called my uncle who is a veteran audio engineer (live concerts, studio recording etc). He put me in touch with his mate who is an engineer in pro audio electronics. I discussed my situation and he has offered to build me a couple of amps using 250w Hypex Ncore NC252MP amplifier modules that will be within my budget. 1
Zaphod Beeblebrox Posted October 31, 2018 Posted October 31, 2018 8 hours ago, Bal said: Thanks so much for all the great responses. I realise I have a lot to learn and totally underestimated what sort of power (and cost) is required to make these speakers sing. I also now realise that I have never really heard the true potential of my old Reference Studio Monitors as I have never listened to them being driven by a high quality amp. I looked into the aftermarket crossovers being sold on ebay, but the feedback from the vintage Infinity crowd wasn’t good. Off the back of this feedback I threw out a lifeline and called my uncle who is a veteran audio engineer (live concerts, studio recording etc). He put me in touch with his mate who is an engineer in pro audio electronics. I discussed my situation and he has offered to build me a couple of amps using 250w Hypex Ncore NC252MP amplifier modules that will be within my budget. The Hypex are certainly one of the better Class D offerings. Show the impedance curve I posted (measured by me several years ago, I might add) and make 100% certain that the Hypex modules can deal with the impedances pictured. The bass impedance dip is far from non-trivial.
Ittaku Posted October 31, 2018 Posted October 31, 2018 I too would be really worried about the hypex modules being able to drive 0.8 ohms satisfactorily. 1
Addicted to music Posted October 31, 2018 Posted October 31, 2018 8 minutes ago, Ittaku said: I too would be really worried about the hypex modules being able to drive 0.8 ohms satisfactorily. Agreed Definately not class D friendly territory. especially after 5Khz to 20khz where it dip below 2ohms. Look elsewhere. 1
eman Posted October 31, 2018 Posted October 31, 2018 10 hours ago, Bal said: Thanks so much for all the great responses. I realise I have a lot to learn and totally underestimated what sort of power (and cost) is required to make these speakers sing. I also now realise that I have never really heard the true potential of my old Reference Studio Monitors as I have never listened to them being driven by a high quality amp. I looked into the aftermarket crossovers being sold on ebay, but the feedback from the vintage Infinity crowd wasn’t good. Off the back of this feedback I threw out a lifeline and called my uncle who is a veteran audio engineer (live concerts, studio recording etc). He put me in touch with his mate who is an engineer in pro audio electronics. I discussed my situation and he has offered to build me a couple of amps using 250w Hypex Ncore NC252MP amplifier modules that will be within my budget. Thanks for the thread. Reminds me to stick with my rebuilt Infinity RSMs. 1
georgehifi Posted October 31, 2018 Posted October 31, 2018 (edited) 1 hour ago, Ittaku said: I too would be really worried about the hypex modules being able to drive 0.8 ohms satisfactorily. Yes and that's without bringing any - phase angle into contention combined with the .8ohm EPDR (equivalent peak dissipation resistance). This could make it look even lower than .8ohm to the amp, pity we don't have a - phase graph on these. Cheers George Edited October 31, 2018 by georgehifi 1
jakestar Posted November 5, 2018 Posted November 5, 2018 Late input but just came across the post. I ran my Kappa 9's with a krell ksa100s amp for many many years. Only 100wpc but plenty of current supply. The only time it looked like running out of omph was when the speakers were set to extended mode. When switched to normal mode they sang. The music the combination made was like a match made in heaven. After selling both the speakers and amp in a downsizing exercise I'm still searching for that same scale of sound. The big current supply amps will do the job as less than 1 ohm impedance loads are hard work. 1
Bal Posted November 6, 2018 Author Posted November 6, 2018 Thanks or all the great feedback and advice - it’s been a really interesting discussion. I raised the concerns outlined above around the ability for the 250w Hypex Ncore modules to handle the dip below 1 ohm. The audio engineer I have been talking to wrote to Hypex with a copy of the impedance graph (very much appreciate that being supplied - a big help) and asked the question. This was their response: ‘I think these drops of impedance to 0.8 ohm should not be an issue at all. Yes of course it can happen that a not so powerful module can go into protection but then I would suggest using a slightly higher power module. One modules I can suggest is the NC502MP. This is a 2 times 500W into 4 ohm module including power supply. If you look at the datasheet each channel can even doe 450W into 2 ohms. https://www.hypex.nl/img/upload/doc/ncore_mp/nc502mp/Documentation/NC502MP_02xx_03xx.pdf” So now I am looking at a 4 channel amp that will use two NC502MP modules, each of which is 2 x 500w. One module for each speaker with separate channels for mid/highs and lows. I will never be pushing a full 500w, but it means if I am only pushing say 200w then the amp will have enough head room to drop down to 1ohm loads for periods of time. Nord Acoustics in the UK make an amp set up exactly like this and it’s way cheaper than some of the other options that have been suggested to me. https://www.nordacoustics.co.uk/product-page/nord-one-mp-nc500-4-6-channel-amplifier-black
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