jackson_ngo Posted May 21, 2004 Share Posted May 21, 2004 Hi all, I'm now interested in building up a home theater set. i've came across some yamaha amps and found out they have an output of 8ohm impedance, but the speakers i came across are running at 6ohms. will that affect the sound or damage the speakers?? Thanks alot Quote Link to comment Share on other sites More sharing options...
JewishAMerPrince Posted May 21, 2004 Share Posted May 21, 2004 Ok...this is not as easy to answer as it may seem. First bear with me while I educate a bit. Impedance in a speaker is not an absolute thing, it varies by frequency of the signal. That is why we refer to a speakers input in terms of "nominal" impedance. This number represents some form of mathematical average of all the speakers impedances at all it's rated frequencies. A speaker rated at 6 ohms nominal impedance may have it's absolute impedance drop to as low as one ohm or may climb to 50 to 60 ohms. That is why we talk about one speaker as being "difficult to drive" by comparison to another of the same rating. Now on the electronics side, a receiver will be rated at the ideal "nominal" impedance of the speaker that should be connected to it. However it will be capable of driving other loads depending on the stability of it's amps. Yammi receivers tend to have stable amps, so I would say that you are probably OK with that combination. Quote Link to comment Share on other sites More sharing options...
marksdad Posted May 21, 2004 Share Posted May 21, 2004 basic rule of thumb i have learned from reading and from polk, is is the speak is rated 4 ohms, run at 4 ohms, if is reted 6-8 ohms run at 8 Quote Link to comment Share on other sites More sharing options...
jackson_ngo Posted May 21, 2004 Author Share Posted May 21, 2004 thanks for your replies, i should how what to do now Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted May 21, 2004 Share Posted May 21, 2004 I just bought a Yamaha RX-V750 and it has selectable outputs for speakers. You can either go with an all 8 ohm system or set it so that the front speakers are a min of 4 ohm and the rest a min of 6 ohm. One of the reasons I went with this unit is for the output selector switch, I am using Heresys as a front channel and they are rated at 4 ohm. Quote Link to comment Share on other sites More sharing options...
IndyKlipschFan Posted May 21, 2004 Share Posted May 21, 2004 I just bought a amp and it has outputs for 3000 speakers and I only have 2... What should I do?? LOL Buy more Klipsch!! Seriously, your fine. Quote Link to comment Share on other sites More sharing options...
avman Posted May 21, 2004 Share Posted May 21, 2004 ---------------- On 5/21/2004 8:16:45 AM cablacksmith wrote: I just bought a Yamaha RX-V750 and it has selectable outputs for speakers. You can either go with an all 8 ohm system or set it so that the front speakers are a min of 4 ohm and the rest a min of 6 ohm. One of the reasons I went with this unit is for the output selector switch, I am using Heresys as a front channel and they are rated at 4 ohm. ---------------- one of the guys i work with retired his Integra surr.sound amp and got a yammy rxv-750;so far he likes it. i often pair yamaha's RXV-series receivers w/klipsch w/great results. i have also used the YPAO setup feature w/good results. my ? to you is:did you use YPAO and if so,what were the results. i am thinking of trying one out in my living room-which is acoustically 'hard'(very reflective)yet has an open back wall...getting the 2-cornwall/3-heresy speaker system to sound right in that room w/out 'ear bleeding'will be a challenge. Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted May 21, 2004 Share Posted May 21, 2004 ---------------- On 5/21/2004 10:55:31 AM avman wrote: one of the guys i work with retired his Integra surr.sound amp and got a yammy rxv-750;so far he likes it. i often pair yamaha's RXV-series receivers w/klipsch w/great results. i have also used the YPAO setup feature w/good results. my ? to you is:did you use YPAO and if so,what were the results. i am thinking of trying one out in my living room-which is acoustically 'hard'(very reflective)yet has an open back wall...getting the 2-cornwall/3-heresy speaker system to sound right in that room w/out 'ear bleeding' ---------------- Well, I have only had it for 2 days but so far VERY good! I did use the YPAO and it did a prety good job. The room has only 2 walls (front and right side) the front wall is rock with LOTS of places for sound to reflect from, the right wall is mostly blank sheet rock with a few pictures on it. The room is about 8 1/2' tall and 12' square. I set the mic for 1 spot that would be close to the main seating average positions. The YPAO set everything and the sound from that spot is very good indeed. The other seats are also good but due to their being closer to 1 speaker or the other the sound is a little "off" but it is still enjoyable. My front speakers are Heresy 2s and the rest of the channels are a mixed bag, though I intend to go to an all Heresy system as money affords. The sound is about as well matched as possible I think, not perfect but then with 3 different make/mod speakers, what do you want? The YPAO decided that the Heresy and AR speakers were "small" and that the rears were "large" even though the satillites are the size of toasters. I think the non-powered sub box with the satillites threw the system a curve ball. As of yet, there isn't a center channel and the yami does a good job of puting the sound in the middle. I have two temp choices for a center speaker, the first is to use a JBL 4312 (which I already have) as a center and mount it above and behind the TV. The other choice is to take the pre-out center and feed it to the audio in on the TV then set the TV to mono and manualy set the volume. This is a cleaner looking option but the sound will suffer I am afraid. I am looking for a Sub to go with this system, any recomendations AVMAN? Quote Link to comment Share on other sites More sharing options...
avman Posted May 21, 2004 Share Posted May 21, 2004 the klipsch rw-12 or another similarly performing sub would be a good choice. yes,the passive sub on the rears made the yammy think those were large speakers-you should leave them that way until you get a powered sub,then switch them to 'small'. thanks, avman. Quote Link to comment Share on other sites More sharing options...
Colin Posted May 21, 2004 Share Posted May 21, 2004 The amplifier has an output RATED at 8-ohms. If it could do better, more watts into 6 or 4-ohms, believe me, they would be quick to tell you about it. Its output is a curve plotted against THD. Typically at very low power (big ole horns) and at very high power, solid-state amplifiers have really high levels of even-order distortion. Which sounds harsh. Every amplifier maker should include a power chart on its back, so tweaking audiophiles can see how low or steep the THD curves actually are a single number tells so very little. The loudspeaker impedance curve is rated with just one number (how silly). Every loudspeaker and sub should include an impedance chart on its back, so tweaking audiophiles can see how low or steep the impedance curves actually are a single number tells so very little. This tells me that the loudspeaker wants a higher quality amplifier, something more capable of driving the low impedances (typically due to the resistance of the woofer). A solid-state amplifier will probably sound better than a low cost vintage integrated tube amplifier in this situation. If you have lower 4-ohm taps, I would certainly try them with this loudspeaker bet it sounds better with them. Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted May 21, 2004 Share Posted May 21, 2004 Colin, I can only speak for the unit I just bought and while it isnt a graph, its specs are as follows: Minimum RMS output power for front, center surround, surround back 20 Hz to 20k Hz, 0.06 THD, 8 ohm = 100w Maximum power (eiaj) 1 kHz, 10% thd, 8 ohm = 140w Dynamic Power (ihf) 8/6/4/2 ohm = 135/170/200/245 w Damping Factor (ihf) 20 Hz to 20 kHz, 8 ohm = 100 or more Frequency Response Cd terminal to front L/R 10 Hz to 100 kHz, -3db Total harmonic distortion Phono to rec out (20 Hz to 20 kHz, 1v) = 0.02% Cd, etc to front L/R (20 Hz to 20 kHz 50w, 8 ohm) =0.06% So other than 8 ohm ratings are listed, granted it is dynamic power not rms but it is listed. Quote Link to comment Share on other sites More sharing options...
avman Posted May 21, 2004 Share Posted May 21, 2004 ---------------- On 5/21/2004 12:49:17 PM Colin wrote: The amplifier has an output RATED at 8-ohms. If it could do better, more watts into 6 or 4-ohms, believe me, they would be quick to tell you about it. ---------------- just a note: the yamahas do rate their amps specified THD from 20Hz to 20KHz. they also show dynamic power output at: 8 ohms-135w 6 ohms-170w 4 ohms-200w 2 ohms-245w 20Hz-20KHz 100 w.p.c. @ .06% THD kudos to yamaha for being willing and able to show specs like this! avman. EDIT: cablacksmith beat me to the 'submit' button! Quote Link to comment Share on other sites More sharing options...
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