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#1
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6 and 8 ohm speakers on one reciver
HI im really new to this and a pretty big novice but my reciever has
two settings either 6 or 8 ohms i just got some 6 ohm center and surround speakers off of the internet and my main speakers are 8 ohms im trying to figure out what would be the better setting on my reciver 6 or 8 or should i just return the 6 ohm speakers and try to find some that are 8 thanks in advance |
#2
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6 and 8 ohm speakers on one reciver
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#3
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6 and 8 ohm speakers on one reciver
On Mar 6, 8:20 pm, Eeyore
wrote: wrote: HI im really new to this and a pretty big novice but my reciever has two settings either 6 or 8 ohms That's damn odd ! Why don't you say what model it is ? Graham my reciever is a pioneer VSX 515 |
#4
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6 and 8 ohm speakers on one reciver
my reciever is a pioneer VSX 515 the manuel says that they recommend
speakers of 8 ohms but can switch it to 6 ohms thanks for the help |
#5
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6 and 8 ohm speakers on one reciver
wrote: Eeyore wrote: wrote: HI im really new to this and a pretty big novice but my reciever has two settings either 6 or 8 ohms That's damn odd ! Why don't you say what model it is ? my reciever is a pioneer VSX 515 I see no mention of 6 ohms here. http://www.pioneer.co.uk/uk/products...5-S/index.html What does the owner's manual say ? Graham |
#6
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6 and 8 ohm speakers on one reciver
on page 51 of the manual it says:
Switching the speaker impedance We recommend using speakers of 8 Ω with this system, but it is possible to switch the impedance setting if you plan to use speakers with a 6 Ω impedance rating. €¢ With the receiver in standby, press STANDBY/ON while holding down the SPEAKER IMPEDANCE button. Each time you do this, you switch between the impedance settings: €¢ SP 6 OHM €“ Use this setting if your speakers are rated at 6 Ω .. €¢ SP 8 OHM €“ Use this setting if your speakers are rated at 8 Ω or more. Gray |
#7
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6 and 8 ohm speakers on one reciver
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#8
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6 and 8 ohm speakers on one reciver
nice thanks man that was exactly what i was thinking just wanted to
check in with someone also do you think an equalizer would be good really dont know about these things |
#11
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6 and 8 ohm speakers on one reciver
On Mar 7, 6:34 am, "Mark D. Zacharias" wrote:
A six-ohm speaker is in reality a conventional eight-ohm speaker. No, it's not, not if they follow any of the standards in place. They're just trying to rate them a bit more accurately these days. A regular eight-ohm model will often dip below 5 ohms near the low-frequency resonance point anyway. Wrong. The impedance is almost always at its MAXIMUM at and near the low frequency resonance. For most 2-way systems, the minimum in0band impedance occurs generaly around the geometric mean between the low frequency resonance and the crossover point. That's typically between 200 and 300 Hz, where it approaches the DC resistance of the woofer voice coil. A similar minimum occurs above the crossover, as the tweeter impedance approaches its DC resistance, ignoring any series resistance that may be in place. FOr reflex systems, there will be two impedance peaks with a local minimum between that. Perhaps that's what you might be thinking of. But the Impedance at that minimum will exceed the DC resistance of the woofer. 3-Way systems are more complicated, and it's not unusual to see the impedance dip BELOW the DC resistance in the midband. |
#12
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6 and 8 ohm speakers on one reciver
thanks ill skip the eq and run it on 6 ohms appreciate all of your
help guys |
#13
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6 and 8 ohm speakers on one reciver
wrote in message oups.com... On Mar 7, 6:34 am, "Mark D. Zacharias" wrote: 3-Way systems are more complicated, and it's not unusual to see the impedance dip BELOW the DC resistance in the midband. It would be quite informative if you would explain how it's possible for the impedance to drop below the DC resistance. Or are you referring to the DC resistance of the driver rather than that of the complete speaker? Thanks, Norm Strong |
#14
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6 and 8 ohm speakers on one reciver
wrote in message
wrote in message oups.com... On Mar 7, 6:34 am, "Mark D. Zacharias" wrote: 3-Way systems are more complicated, and it's not unusual to see the impedance dip BELOW the DC resistance in the midband. It would be quite informative if you would explain how it's possible for the impedance to drop below the DC resistance. DC resistance does not include loading caused by drivers that have capacitors in series with them. System impedance does include loading caused by drivers that have capacitors in series with them. What about a system with an electrostatic tweeter whose impedance decreases to very low levels at high frequencies What about a system with a constant-directivity horn whose ferequency-shapring network's impedance decreases to very low levels at high frequencies? |
#15
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6 and 8 ohm speakers on one reciver
On Mar 7, 3:17 pm, wrote:
wrote in message oups.com... On Mar 7, 6:34 am, "Mark D. Zacharias" wrote: 3-Way systems are more complicated, and it's not unusual to see the impedance dip BELOW the DC resistance in the midband. It would be quite informative if you would explain how it's possible for the impedance to drop below the DC resistance. Or are you referring to the DC resistance of the driver rather than that of the complete speaker? The DC resistance of the speaker is almost always the DC resistance of the woofer. Be that as it may, consider 3 hypothetical drivers, a woofer, a midrange and a tweeter. Assume, for simplicity that each exhibits an essentially resistive impedance of 8 ohms. Combine them with a 3-way 2nd Butterworth crossover parallel passive ladder-type network with crossover frequencies of, oh, 500 Hz and 4 kHz and measure the resulting impedance. It will dip significantly below 8 ohms in the midband, i.e., below the DC resistance of the midrange driver, down to about 6 ohms. This is, in essence, the midrange is running partially in parallel with both the woofer and the tweeter. In detail, consider the following SPICE netlist that illustrates the problem: LWoof 1 2 3.6MH CWoof 2 0 28UF RWoof 2 0 8 CMidH 1 3 28UF LMidH 3 0 3.6MH LMidL 3 4 0.45MH CMidL 4 0 3.52UF RMid 4 0 8 CTweet 1 5 3.52UF LTweet 5 0 0.45MH RTweet 5 0 8 And the resulting impedance, plotted every octave, looks like: 20 8 40 8 80 8 160 8.01 320 8.07 640 7.54 1280 6.29 2560 5.92 5120 7.38 10200 7.96 20500 7.99 There are other topoologies, such as described by Bullock, that alleviate this problem somewhat, but not completely. |
#16
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6 and 8 ohm speakers on one reciver
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#17
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6 and 8 ohm speakers on one reciver
"Mark D. Zacharias" wrote: wrote: nice thanks man that was exactly what i was thinking just wanted to check in with someone also do you think an equalizer would be good really dont know about these things A six-ohm speaker is in reality a conventional eight-ohm speaker. Depends how you measure the impedance. I'm not sure you're right btw. In fact I'm fairly confident you're wrong. Graham |
#18
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6 and 8 ohm speakers on one reciver
"Mark D. Zacharias" wrote: A regular eight-ohm model will often dip below 5 ohms near the low-frequency resonance point anyway. So a six ohm one will probably dip below 4 ohms. What exactly is your point ? Graham |
#19
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6 and 8 ohm speakers on one reciver
Eeyore wrote:
"Mark D. Zacharias" wrote: A regular eight-ohm model will often dip below 5 ohms near the low-frequency resonance point anyway. So a six ohm one will probably dip below 4 ohms. What exactly is your point ? Graham Well, my point was invalidated anyway since I misspoke on the impedance at resonance, but what I was trying to say was that traditional 8-ohm ratings have in many cases been supplanted with 6-ohm ratings, with no apparent electrical change to the speakers themselves. Mark Z. |
#20
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6 and 8 ohm speakers on one reciver
"Mark D. Zacharias" wrote: Eeyore wrote: "Mark D. Zacharias" wrote: A regular eight-ohm model will often dip below 5 ohms near the low-frequency resonance point anyway. So a six ohm one will probably dip below 4 ohms. What exactly is your point ? Well, my point was invalidated anyway since I misspoke on the impedance at resonance You meant at low frequencies. but what I was trying to say was that traditional 8-ohm ratings have in many cases been supplanted with 6-ohm ratings, with no apparent electrical change to the speakers themselves. You're mistaken. On what basis other than speculation do you think there were no changes to the speakers ? Graham |
#21
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6 and 8 ohm speakers on one reciver
wrote in message ps.com... On Mar 7, 3:17 pm, wrote: wrote in message oups.com... On Mar 7, 6:34 am, "Mark D. Zacharias" wrote: 3-Way systems are more complicated, and it's not unusual to see the impedance dip BELOW the DC resistance in the midband. It would be quite informative if you would explain how it's possible for the impedance to drop below the DC resistance. Or are you referring to the DC resistance of the driver rather than that of the complete speaker? The DC resistance of the speaker is almost always the DC resistance of the woofer. Be that as it may, consider 3 hypothetical drivers, a woofer, a midrange and a tweeter. Assume, for simplicity that each exhibits an essentially resistive impedance of 8 ohms. Combine them with a 3-way 2nd Butterworth crossover parallel passive ladder-type network with crossover frequencies of, oh, 500 Hz and 4 kHz and measure the resulting impedance. It will dip significantly below 8 ohms in the midband, i.e., below the DC resistance of the midrange driver, down to about 6 ohms. This is, in essence, the midrange is running partially in parallel with both the woofer and the tweeter. In detail, consider the following SPICE netlist that illustrates the problem: LWoof 1 2 3.6MH CWoof 2 0 28UF RWoof 2 0 8 CMidH 1 3 28UF LMidH 3 0 3.6MH LMidL 3 4 0.45MH CMidL 4 0 3.52UF RMid 4 0 8 CTweet 1 5 3.52UF LTweet 5 0 0.45MH RTweet 5 0 8 And the resulting impedance, plotted every octave, looks like: 20 8 40 8 80 8 160 8.01 320 8.07 640 7.54 1280 6.29 2560 5.92 5120 7.38 10200 7.96 20500 7.99 There are other topoologies, such as described by Bullock, that alleviate this problem somewhat, but not completely. That's what I thought you were referring to, but I just wanted to make sure we were on the same wavelength. Thanks a bunch, Norm |
#22
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6 and 8 ohm speakers on one reciver
Eeyore wrote:
"Mark D. Zacharias" wrote: Eeyore wrote: "Mark D. Zacharias" wrote: A regular eight-ohm model will often dip below 5 ohms near the low-frequency resonance point anyway. So a six ohm one will probably dip below 4 ohms. What exactly is your point ? Well, my point was invalidated anyway since I misspoke on the impedance at resonance You meant at low frequencies. but what I was trying to say was that traditional 8-ohm ratings have in many cases been supplanted with 6-ohm ratings, with no apparent electrical change to the speakers themselves. You're mistaken. On what basis other than speculation do you think there were no changes to the speakers ? Graham Because I've worked with the stuff for the past thirty years and noticed no change other than the "nominal" rating. Notice the word "nominal". Mark Z. |
#23
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6 and 8 ohm speakers on one reciver
"Mark D. Zacharias" wrote: Eeyore wrote: "Mark D. Zacharias" wrote: but what I was trying to say was that traditional 8-ohm ratings have in many cases been supplanted with 6-ohm ratings, with no apparent electrical change to the speakers themselves. You're mistaken. On what basis other than speculation do you think there were no changes to the speakers ? Because I've worked with the stuff for the past thirty years and noticed no change other than the "nominal" rating. Notice the word "nominal". For most of the last 30 years I've only ever known one make of equipment designed for 6 ohm speakers (WEM) and they are indeed 6 ohms rather than 8. Nominal isn't *quite* as vague a term as you like to imply. Graham |
#24
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6 and 8 ohm speakers on one reciver
Eeyore wrote:
"Mark D. Zacharias" wrote: Eeyore wrote: "Mark D. Zacharias" wrote: but what I was trying to say was that traditional 8-ohm ratings have in many cases been supplanted with 6-ohm ratings, with no apparent electrical change to the speakers themselves. You're mistaken. On what basis other than speculation do you think there were no changes to the speakers ? Because I've worked with the stuff for the past thirty years and noticed no change other than the "nominal" rating. Notice the word "nominal". For most of the last 30 years I've only ever known one make of equipment designed for 6 ohm speakers (WEM) and they are indeed 6 ohms rather than 8. Nominal isn't *quite* as vague a term as you like to imply. Graham I didn't say "vague". And yes, they are closer to six ohms. That's EXACTLY the reason for my comments. Used to be the same speakers were referred to as eight ohms, now they are referred to as six. I measure them often enough to have satisfied myself that it is the verbiage, not the speaker drivers, that have changed. Mark Z. |
#25
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6 and 8 ohm speakers on one reciver
"Mark D. Zacharias" wrote: Eeyore wrote: "Mark D. Zacharias" wrote: Eeyore wrote: "Mark D. Zacharias" wrote: but what I was trying to say was that traditional 8-ohm ratings have in many cases been supplanted with 6-ohm ratings, with no apparent electrical change to the speakers themselves. You're mistaken. On what basis other than speculation do you think there were no changes to the speakers ? Because I've worked with the stuff for the past thirty years and noticed no change other than the "nominal" rating. Notice the word "nominal". For most of the last 30 years I've only ever known one make of equipment designed for 6 ohm speakers (WEM) and they are indeed 6 ohms rather than 8. Nominal isn't *quite* as vague a term as you like to imply. I didn't say "vague". And yes, they are closer to six ohms. That's EXACTLY the reason for my comments. Used to be the same speakers were referred to as eight ohms, now they are referred to as six. I measure them often enough to have satisfied myself that it is the verbiage, not the speaker drivers, that have changed. It depends entirely what frequency you measure it at. The best way would actually be with band-limited noise I reckon. I do not however accept that a typical 8 ohm speaker is in fact closer to 6 ohms. In fact it's an area I've taken quite an interest in wrt 'impedance compensation' in the past and I'nt come across anything in my area of interest that would support your assertion. Graham |
#26
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6 and 8 ohm speakers on one reciver
On Mar 9, 10:33 am, Eeyore
wrote: I didn't say "vague". And yes, they are closer to six ohms. That's EXACTLY the reason for my comments. Used to be the same speakers were referred to as eight ohms, now they are referred to as six. I measure them often enough to have satisfied myself that it is the verbiage, not the speaker drivers, that have changed. It depends entirely what frequency you measure it at. For all but the most trival examples, loudspeaker impedance is not measured at any one frequency, not correctly, at any rate. Despite all the abcking-and-forthing here on this topic, there exist clear and unambiguous standards for determing and stating the impedance of loudspeakers. The fact that many manufacturers and most commentators are either unaware of or choose to ignore them does not render them irrelevant. For example, here's the relevant section from IEC 268-5: 7. Impedance 7.1 Rated impedance Characteristic to be specified The rated impedance of a loudspeaker or loudspeaker systemis that value of a pure resistance which is to be substitutedfor the loudspeaker or system when defining the available electric power of the source. This is to be specifiedby the manufacturer. Note: The rated impedance specified by the manufacturer normally represents the lowest value of the modulus of the impedance in that part of the rated frequency range, where the maximum power is to be expected, and is normally not more than 20% higher than the lowest value of the modulus of the impedance at any frequency within the rated frequency range. 7.2 Impedance curve Characteristic to be specified Description, usually presented in the form of a graph, of the modulus of the impedance as a function of frequency, measured under normal working conditions. Now, we have a common means by which we can come up with a figure. Given that the broad average specturm of music tends to be weighted twoards the lower midrange, that says that the minimum impedance ABOVE resonance and BELOW the middle of the band, i.e. 150-1000 Hz, give or take, can be taken as the "rated" impedance of the system. And, interestingly enough, for most systems (not all, to be sure), that value is generally in the realm of 5-20% above the DC resistance of the woofer. The fact that the impedance might drop significantly below that level at substantially higher frequencies (say 8-12 kHz) is, under the standard, irrelevant because there's simply much less power produced in that band under the vast majority of circumstances. And, if there is a LARGE discrepancy between the "rated" impedance according to the above citation and some anomolous behavior, the impedance curve reveals all. But you CAN'T get there without the impedance curve. You may be able to distill to to a single, reasonable number, but NOT without FULL knowledge of the impedance over the full rated bandwidth of the system. The best way would actually be with band-limited noise I reckon. No, the method described above, in conjunction with an understanding of the relevant section of the remainder of IEC268 is best, because it is a public standard which everyone can follow I do not however accept that a typical 8 ohm speaker is in fact closer to 6 ohms. The problem being is assumption that "typical 8 ohm speaker" has a meaningful definition. My own data, based on several thousand measurements, suggests that while the average may meet your criteria, the variances are large. In fact it's an area I've taken quite an interest in wrt 'impedance compensation' in the past and I'nt come across anything in my area of interest that would support your assertion. Well, despite Mr. Zacharias' earlier assumptions of low- frequency impedance, the data I have arrayed before me, specifically the large variances from the average, suggest your assertion has some challenges. That's further supported by the fact that most speaker literature is marketing spin, and an important feature (indeed, requirement) of such spin is single-number "figures of merit," and when it's about marketing, facts become less important. Thus, it is not unheard of at all to see a speaker which, by IEC268-5 sec. 7.1 (op cite) has a rated impedance of 5.9 ohms get listed in the brochure as "nominal 8 ohm impedance". Let's take a real-world example: the classic AR3A. The brochure for the AR3a (published 9/74) states quite clearly, and I quote: Impedance: 4 ohms Now, the ACTUAL impedance is substantially below 3.2 ohms from 78 Hz to 400 Hz, and below 3 ohms from about 85 Hz to 145 Hz. By the criteria defined in IEC268-5 7.1, this is a 3 ohm speaker, clear an unambiguously, because "The rated impedance specified by the manufacturer normally represents the lowest value of the modulus of the impedance in that part of the rated frequency range, where the maximum power is to be expected" is 3 ohms, and cannot be any greater than 3.6 ohms, because: "[it] is normally not more than 20% higher than the lowest value of the modulus of the impedance at any frequency within the rated frequency range." 3 ohms + 20% = 3.6 ohms, and 3.6 ohms != 4 ohms QED |
#27
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6 and 8 ohm speakers on one reciver
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#28
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6 and 8 ohm speakers on one reciver
On Mar 9, 7:47 pm, Eeyore
wrote: wrote: Eeyore wrote: I didn't say "vague". And yes, they are closer to six ohms. That's EXACTLY the reason for my comments. Used to be the same speakers were referred to as eight ohms, now they are referred to as six. I measure them often enough to have satisfied myself that it is the verbiage, not the speaker drivers, that have changed. It depends entirely what frequency you measure it at. For all but the most trival examples, loudspeaker impedance is not measured at any one frequency, not correctly, at any rate. So why did you snip the following line of my post ? You mean the line that said: The best way would actually be with band-limited noise I reckon. Which, in fact, I DID quote later in my post, and responded to accordingly. And when trimming, do please attribute the correct poster will you ? Where did I attribute anything to you that you didn't write? The level of attribution, "" vs "" spells it out pretty clearly using the well-established traditions of usenet newsgroup posting that have been in place for several decades now. Besides that, do you have any substantive technical replies to the technical content of my posting? I would be interested in your views. Specifically, given your comment: "it's an area I've taken quite an interest in wrt 'impedance compensation' in the past" I am curious as to what you mean by "impedance compensation" and whether it is something along the lines of complex conjugate matching or something else. |
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