|   need a 1.3 ohm AMP | csrusa77
Sep 6, 2002 1:49 PM | | I have RS-8Kappas that have a minimum impeadance of 1.3 Ohms at 40 Hz. These speakers keep shutting down my reciever. The speakers have 2 sets of terminals and I would like to connect a Power-Amp to the terminals that power only the 12" woofers if thats would be ok. (I am assuming that the low impedance is only related to the woofer.)
Does anyone recommend an amp? I would prefer 1 amp to power both speakers, if there is such a thing.
BTW:The advice that I have recieved at this site has been incredible. Thanks especially to the person that goes by "A", your knowledge on my issue was far superior. |
| More Info | csrusa77
Sep 6, 2002 2:39 PM | | -SPEAKER: RS8 KAPPA Infinity
*4-Way 250 Watt Speaker Home Speakers
*Manufacturing Date: 1987 - 1989
*Frequency Response (+/-3dB) 33Hz - 45kHz
*Crossover Frequencies 80Hz, 800Hz, 4500Hz
*Power Rating 50 - 250 watts RMS
*Sensitivity (@1watt.1 meter) 89dB
-RECIEVER: Yamaha RX-V800
*100 watts per channel
*6 line output jacks for external amps, 1 for each speaker and 1 for sub
*Impedance switch for 4-8ohms speakers |
| re: need a 1.3 ohm AMP | Pat D
Sep 6, 2002 6:09 PM | | See what a good review by Julian Hirsch can do to assist you! You probably have put your finger on the problem. Despite what some say, measurements really can be useful.
I would think your receiver, like most other receivers, is not really suitable for a speaker with such a low minimum impedance. For a short term fix, you might put 1 or 2 ohm resistors in the speaker lines attached to the positive outputs of your receivers and keep the volume levels moderate. This may change the sound of the speakers somewaht, but it would also increase the impedances your receiver 'sees,' and so lower the current requirements.
You are going to need an amplifier that can supply a lot of current into low impedances. Just what will be suitable will also depend on your listening habits, how loud you play. If I were in your situation, I would probably look at the bigger Brystons (4B or 14B), but they're not cheap, although there are much more expensive amps. It looks like there are some user reviews on this site and you could see what amplifiers the serious ones use.
You might also ask at other sites to try to find some who use the same speakers. |
| re: need a 1.3 ohm AMP | Paul L
Sep 6, 2002 8:50 PM | | Yep, I know they are one of the most difficult speakers to drive. The most is Apogee Scintelle (spelling?). In order to drive the Kappa 8 well, you can either get a gooood power amp but that will cost quite a bit. Another option is get a modestly priced good amp for top such as the Monarchy SM70-Pro and a huge current amp for the woofer. The SM70-Pro itself can drive 2.Ohm load so a vertical biamping may be an economic option for you.
Paul Lam
P.L.C.Lam Consulting Inc. |
| re: need a 1.3 ohm AMP | csrusa77
Sep 6, 2002 9:22 PM | | I would love to use such a reasonably priced amp, but can the SM70-Pro deliver enough power for these 50-> 250 watt speakers? |
| re: need a 1.3 ohm AMP | Paul L
Sep 7, 2002 1:10 PM | | You speaker is relatively efficient. The SM70-Pro has plenty of drive for your speaker if you room is not huge. It is how loud your ears can handle.
Paul Lam
P.L.C.Lam Consulting Inc. |
| A difficult electrical load | skeptic
Sep 8, 2002 4:34 AM | | I'm sorry to say that you will need a first class amplifier which is rated to be stable with ANY passive load. This is an extremely difficult electrical load for many amplifiers. Many modern (currently avaialable) mass market receivers and amplifiers will most likely not work because they are not designed to handle this kind of load. Check with the manufacturer first and get the right to return for a full cash refund or at least store credit in writing before you buy. If you buy new equipment, you will need a separate power amplifier at the very least, not an integrated or receiver. If you buy used, there are many older models including receivers which might qualify. I'd try a big Marantz from the 70s or 80s. If you use a tube amplifier, set the output transformer tap on the lowest impedence which is ususally 4 ohms for the best match. When you make your choice, connect the amp using normal 16 gage zip cord before trying any exotic audiophile speaker wires. the construction of some of them can compound the problem. If you install a resistor in series with the speaker, it sould be 2 ohms and at least 10 or 20 watts. Be warned that it may get very hot to the touch so it should be well ventillated and not in contact or close proximity with anything else. I'd also wire a slo blow fuse in series with the output as well if the amplifier doesn't already have one to protect the amplifier output stage. I'd start with 3 amps and work my way up cautiously if that one keeps blowing. Good luck. |
| re: need a 1.3 ohm AMP | A
Sep 9, 2002 1:36 PM | | I advise you to go to your local stores that sell good equipment, and look for an amplifier that the manufacturer claims, in writing, can handle a 1.3 ohm load or less (probably, if you find one, it will be rated for 1 ohm). You might be able to get away with an amplifier that is rated for 2 ohm use, but I would not recommend trying it, as I seem to recall you are using these speakers in a home theatre and are using no subwoofer, so all of the bass explosions in movies are going to put serious demands on the power amplifier that you choose. And if you destroy the expensive amplifier you buy, the manufacturer may not wish to help you out, as 1.3 ohms is significantly less than 2 ohms, and they would be right to tell you that they never intended for their amp to be used for such a low impedance; the fact that Infinity did not properly label the speaker's impedance is the fault of Infinity, not the manufacturer of the amplifier.
You will very likely have some trouble finding an amplifier rated for 1.3 ohms or less, and if you do find one, don't be surprised if it is very, very expensive.
Also, beware of salesmen wanting to sell you something not rated for such low impedances. If they have nothing that would be a good idea for you to buy, they will often want to sell you something anyway. Don't fall for any slick BS. You have speakers that are 1.3 ohms at a frequency that you plan on playing at very high levels. This is an extremely difficult load. Before you part with any money, look on the back of the amplifier to see what the manufacturer has printed as the lowest impedance to be hooked up to the speaker terminals. Trust what it says there, not what some salesman may claim.
What would probably be less expensive (and certainly far easier to find) would be to purchase a subwoofer instead, and use your receiver's bass management to send all of the bass to the subwoofer. You may also get better bass that way, though it will depend on the particular subwoofer selected. The reason this would work is that you would set your receiver to consider your main speakers as "small", and therefore it would not send anything to the main speakers at 40 Hz.
You may not like that idea, but I think you may warm up to the idea after visiting a few audio shops and looking at what you will be facing in getting an amplifier that will properly and safely work with your speakers. And again, you may even get better bass with a separate subwoofer, depending on what you buy and how you set it up. You could get deeper bass with a subwoofer than you will ever get with your Infinity speakers (yes, I know, they do give some pretty deep bass; I've read the article to which you have a link; but you can get deeper bass than that with a subwoofer, especially at the probable cost of a power amp suitable for driving your Infinitys). |
| Whatever you say Mr. A | csrusa77
Sep 9, 2002 7:01 PM | | A,
You're absolutely right. I'm going to buy a sub and set my speakers to a smaller setting. It's definitely the best solution for me. I recieved these speakers as a gift so it's not a big loss to not take full advantage of them (which would be more costly to do so).
I think I'm going to go with the SVS-Pci 20-39.
Thanks again for all of your good advice. |
| Whatever you say Mr. A | A
Sep 10, 2002 8:58 AM | | What a nice gift you received! What a generous friend you have!
I had another thought that you may wish to consider (though I would still probably go with a subwoofer, and I have heard good things about the SVS line). You might have better luck finding an amplifier that can deal with low impedances if you looked in stores that sell amplifiers to musicians (e.g., your local guitar store, etc.). The downside to looking for an amplifier at such stores is that you will need to pay attention to the types of connections that are possible, and you will also want to make sure that any amplifier you select is suitable for use in music reproduction (because, for example, some professional equipment is not designed to reproduce the entire frequency spectrum, but only a portion of it, such as a PA amplifier for reproducing speech).
You state:
> Whatever you say Mr. A
I hope that you don't mean that literally, but instead think carefully about everything I say before you believe it. If someone is right about one thing, it does not mean that they will always be right.
One more thing: You may be interested in reading some of the past discussions regarding biwiring (there is disagreement about whether it accomplishes anything audible). You can use the search feature to find them. Here is one thread about that subject with opposing positions expressed:
Widowmaker "What is bi-wiring and does it improve sound quality?" 8/27/02 8:20pm |
| Whatever you say Mr. A | csrusa77
Sep 10, 2002 9:38 AM | | Thats a good idea, to check musician amps.
I said whatever you say because, the advice you have given me and also from reading your other discussions has lead me to believe that you are extremely well informed and experienced and most of all have an absolutely unbiased opinion about the subject matter that you discuss.
Maybe instead of unbiased I should say neutral as far as not favoring any one-way, side or brand. |
| re: need a 1.3 ohm AMP | skeptic
Sep 12, 2002 4:29 AM | | High quality amplifiers stable with ANY passive load have been made for a very long time. The Crown DC 300 introduced in 1968 for example was such a unit and that was almost 35 years ago. Since then there have been many others. I'd bet any McIntosh tube amp could handle it when set for the 2 ohm tap. Apparantly, this speaker was not intended for use with mass market receivers. |
| re: need a 1.3 ohm AMP | Pat D
Sep 17, 2002 12:41 PM | | You know, when I went back and read his earlier post, my respect for his Yamaha receiver sure grew: even with that load, it apparently only shuts down on difficult HT passages! It might even work reasonably with 2 channels only. But I still have to agree that he needs an even better amp. |
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