4 ohm guys, recommend some receivers - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 32 Old 05-11-2016, 07:46 AM - Thread Starter
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4 ohm guys, recommend some receivers

Everyone on 4 ohm speakers: please recommend something you use or have experience with, and if you actually need to cross over your sub to make it work, and do you notice any sacrifice in sound quality?

I'm contemplating 4 ohm speakers, and whether or not to go all out and get separates or a high end receiver.

Something funny is that Denon has a few 4 ohm capable receivers (per their sales literature), and marantz separates don't mention anything past 6.
Denon:
Quote:
Each channel is rated at 150 watts (8 ohms, 20Hz~20kHz, 0.05%THD), and all channels are able to safely drive lower impedance speakers (down to 4 ohms).
Marantz Amp:
Quote:
150 W/ch (8 ohms), 180 W/ch (6 ohms)
RMS Power (20 Hz - 20 kHz) (and) High current, high bandwidth discrete power transistors can handle short term musical bursts
with aplomb, even into difficult low impedance speaker loads.
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post #2 of 32 Old 05-11-2016, 07:52 AM
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My Yamaha RX Z-11 drove M-L electrostatics with ease. Only available used. If you don't need 11 ch, you can go with RX Z-7. I'm using a Denon receiver, now; with Emotiva separates for bed channels, so that I could get the new HDMI and HDCP for Polk speakers that go down to 2 ohms in some octaves.

JVC RS600 Chad-callibrated, 120" 1.3g in Batcave HT, Denon X8500 Polk LSiM703 fronts,
RTi-12 rears, LSiM 706 center, Monitor 40 Heights, Monitor 60 FW, FXiA4 Bi-pole sides,
LSiC top front, Infinity 6" VOG. 4X 12" subs w/mini DSP on sub 1 and nearfield 18" from sub 2.
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post #3 of 32 Old 05-11-2016, 08:29 AM
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My old Pioneer Elite had no problems driving my 4-ohm (Magnepan) speakers.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #4 of 32 Old 05-11-2016, 10:12 AM
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I have a pair of MA Silver 8 towers that are rated at 4ohms driven by Anthem MRX-720 and oh boy do they sound good.
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post #5 of 32 Old 05-11-2016, 11:27 AM
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Realistically whether or not you need a "4-ohm rated" AVR will depend upon the speakers, their actual impedance and sensitivity, your listening position from them, what you listen to and how loudly, room size, etc. etc. etc. An AVR rated for 8-ohm speakers will probably have no problems driving a 4-ohm design that is almost purely resistive, 100 dB/W/m efficient, only six feet away, played at 60 dB SPL with 80 dB peaks, backed by a good sub. An AVR rated for 4 ohms will probably die faced with a pair of speakers rated nominally 4 ohms but dipping to 1 ohm at 50 Hz with a highly capacitive phase angle, sensitivity of 80 dB/W/m, sitting in a large room fifteen or twenty feet away from the listener, no sub, and asked to reach 120 dB peaks.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #6 of 32 Old 05-11-2016, 11:30 AM
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Output power into 4 Ohms is a challenge for an AVR, regardless of brand/model...
If U are using 4 Ohm. low sensitivity loudspeakers and the room is large U better consider a separate, component power amplifier..


Just my $0.02...
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post #7 of 32 Old 05-11-2016, 05:04 PM - Thread Starter
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Room Size roughly 800 sq ft in a basement, and its long not wide. Behind the HT is a pool table and mini bar area. Probably not very loud because my wife hates loud music, and loud movies. I usually have to turn the TV up because I have a tougher time following the dialog.

MAINS
SENSITIVITY
90 dB SPL (2.83 V/1m). NOMINAL

IMPEDANCE
4 ohm.

SUGGESTED AMPLIFIER POWER OUTPUT
50W – 300W, without clipping.

CENTER
SENSITIVITY

88 dB SPL (2.83 V/1m).

NOMINAL IMPEDANCE 

4 ohm.

SUGGESTED AMPLIFIER POWER OUTPUT 

50W – 300W, without clipping.
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post #8 of 32 Old 05-12-2016, 08:47 AM - Thread Starter
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HIFINEWS magazine tested them: http://www.excelia-hifi.cz/sonus-fab...news_05_14.pdf

Quote:
- the nominal 4ohm specification should imply a minimum of 3.2ohm (80% of nominal) but we recorded a dip down to 2.6 ohm at 103 hz, so this is really a 3 ohm design. Given that EPDR is typically half the minimum modulus figure, the olympica III might have proved to be a tough load to drive but well controlled phase angles result in a minimum EPDR of 1.7ohm at 81Hz, so its partnering amplifier will be no more stressed than with many of today's floorstanders.
All this is over my head. While I have learned what some of these things mean from learning here, I don't know how this relates in practice to me. I'm going Friday to audition some AVRs and separates.
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post #9 of 32 Old 05-15-2016, 04:40 PM - Thread Starter
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I couldn't actually get my place to Demo McIntosh vs Flagship AVR
I could however hear marantz separates vs Mcintosh 2 channel AVR lol (he promises that the Mc AVR sounds just like the separates though).

I think the Mc wins at volumes up to 95-100 db (the scientific measurement of sound not the dial setting), however it isn't exactly a landslide. Crucial listening of my favorite songs and I could pick out defects the highs and only occasionally. The bass may have been a little punchier too, but the highs took my focus. For all I know it's the DAC between the two.
Speaker placement mattered much more than electronic choice.

Marantz separates at 150 watts per channel wasn't exactly underpowered with 2 of 4 ohm mains.
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post #10 of 32 Old 05-15-2016, 04:53 PM
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A decent easy reference point, a capable 4 ohm amp should be rated pretty much exactly double its 8 ohm specs.

Last edited by redgum11; 05-15-2016 at 05:47 PM.
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post #11 of 32 Old 05-17-2016, 10:28 PM
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Quote:
Originally Posted by aelahi View Post
I have a pair of MA Silver 8 towers that are rated at 4ohms driven by Anthem MRX-720 and oh boy do they sound good.
I had the exact same system. Must say it sounded good - very good! So good I upgraded to B&W 803d3s and a Krell integrated amp. I use the HT by-pass to run the B&Ws. The Anthem 710 runs when in HT mode.

The Anthem was fine on the 4 ohms.
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post #12 of 32 Old 08-05-2017, 06:43 PM
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Quote:
Originally Posted by M Code View Post
Output power into 4 Ohms is a challenge for an AVR, regardless of brand/model...
If U are using 4 Ohm. low sensitivity loudspeakers and the room is large U better consider a separate, component power amplifier..


Just my $0.02...
I have to agree, however, I have the large Dunlavy SC IV's and they are 4 ohms, but 90 to 91 db efficient.
I have an Onkyo TX-NR 809 that drives the piss out of them, in an 18 by 22 foot room.
The Onkyo TX-NR 809 has preamp outs, so I have compared it against several power amps, and guess what ? The Onkyo 809 holds it's own, as far as sound quality goes. I had a Pioneer Elite SC 85 receiver, with the D3 Digital Amp, but the Onkyo sounded better.
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post #13 of 32 Old 08-05-2017, 07:02 PM
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I run a za5000es with 4ohm speakers. Sounds great.
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post #14 of 32 Old 12-31-2018, 03:42 PM
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I know it has been awhile since anyone has posted to this thread, but I just ran into this scenario. Didn't realize after all these years that the Polk Lsi9 that I use for left and right in home theater are 4 ohm. I always wondered why I never seemed to get the performance out them that I expected and from all the reviews I had read. I had driven them with various AVRs (Onkyo, Yamaha, Denon, Sony) over the years from 60-90 watts per channel. This Christmas I was able to replace several home theater components. Got a new Sony 65" 900f TV, Sony X700 Blu-ray player, and Sony STRDN1080 AVR. With the new 1080 I was able to bi-amp the Lsi9 speakers. Previously I had them bi-wired. The 1080 is rated at 165 watts per channel in surround mode at 6 ohms. My wife is the main user of TV so I know it will never get pushed loud (thus stressing the 1080 into lower ohm loads as it is only rated to 6 ohms). But wow, the difference is night and day on the sound, presence, quality (insert all adjectives here lol). Never knew what I had been missing all these years. New something was amiss but would always forget about it and I rarely have time to sit and watch. Just wanted to put my two cents in. Receiver was on sale at Best Buy for couple hundred off retail. Guess I'm just trying to say you don't have to drop big money on AVR for 4 ohm speakers, unless you really intend on getting loud with them, then you might want to get one that is genuinely rated for 4 ohms. Eons ago I did have dedicated mono amps on each speaker (Outlaw Audio when they first hit market) and even then the speakers just didn't sound right. Those mono amps were rated around 100-125 watts per channel if I remember correctly. Anyway, all is well now. Might even do some of the Lsi crossover mods (I know I way late to the game, as they have made Lsi9 speakers in a long time lol).
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post #15 of 32 Old 06-19-2019, 01:22 AM
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Quote:
Originally Posted by swoodall View Post
I know it has been awhile since anyone has posted to this thread, but I just ran into this scenario. Didn't realize after all these years that the Polk Lsi9 that I use for left and right in home theater are 4 ohm. I always wondered why I never seemed to get the performance out them that I expected and from all the reviews I had read. I had driven them with various AVRs (Onkyo, Yamaha, Denon, Sony) over the years from 60-90 watts per channel. This Christmas I was able to replace several home theater components. Got a new Sony 65" 900f TV, Sony X700 Blu-ray player, and Sony STRDN1080 AVR. With the new 1080 I was able to bi-amp the Lsi9 speakers. Previously I had them bi-wired. The 1080 is rated at 165 watts per channel in surround mode at 6 ohms. My wife is the main user of TV so I know it will never get pushed loud (thus stressing the 1080 into lower ohm loads as it is only rated to 6 ohms). But wow, the difference is night and day on the sound, presence, quality (insert all adjectives here lol). Never knew what I had been missing all these years. New something was amiss but would always forget about it and I rarely have time to sit and watch. Just wanted to put my two cents in. Receiver was on sale at Best Buy for couple hundred off retail. Guess I'm just trying to say you don't have to drop big money on AVR for 4 ohm speakers, unless you really intend on getting loud with them, then you might want to get one that is genuinely rated for 4 ohms. Eons ago I did have dedicated mono amps on each speaker (Outlaw Audio when they first hit market) and even then the speakers just didn't sound right. Those mono amps were rated around 100-125 watts per channel if I remember correctly. Anyway, all is well now. Might even do some of the Lsi crossover mods (I know I way late to the game, as they have made Lsi9 speakers in a long time lol).

Hi Swoodall,


I have just bought myself the DN1080 and keen to hear it but realised my front speakers are 4ohm and have gone back and fourth with sony tech support (who recommend against use w 4ohm speaker) and the speaker manufacturer (Australia's biggest manufacturer who say they have never had to recommend specific amp/AVR's for their speakers) to try and work out whether to hang on to the DN1080 against SONY's advice. My previous AVR was a Yamaha which was rated at 8ohm and never had a problem.


I don't plan to bi-wire my speakers but from what I can tell this doesn't affect impedance anyways. I would also be wiring it up to a centre speaker as well as 2, 6ohm rears and ceiling speakers. Have you had any problems with ongoing use of the DN1080 with your 4ohm speakers? It's such a polarised discussion from what I can tell - I'm just going to have to get as much experiential feedback as I can. Thanks for any info you can provide
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post #16 of 32 Old 06-19-2019, 05:33 AM
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Quote:
Originally Posted by dabl81 View Post
Hi Swoodall,


I have just bought myself the DN1080 and keen to hear it but realised my front speakers are 4ohm and have gone back and fourth with sony tech support (who recommend against use w 4ohm speaker) and the speaker manufacturer (Australia's biggest manufacturer who say they have never had to recommend specific amp/AVR's for their speakers) to try and work out whether to hang on to the DN1080 against SONY's advice. My previous AVR was a Yamaha which was rated at 8ohm and never had a problem.


I don't plan to bi-wire my speakers but from what I can tell this doesn't affect impedance anyways. I would also be wiring it up to a centre speaker as well as 2, 6ohm rears and ceiling speakers. Have you had any problems with ongoing use of the DN1080 with your 4ohm speakers? It's such a polarised discussion from what I can tell - I'm just going to have to get as much experiential feedback as I can. Thanks for any info you can provide
I haven't had any problems, but again I rarely listen/watch anymore. Wife is main user and she typically never goes more than 1/3 volume for everyday listening. Every once in while she does crank it up when watching a movie or listening to music while vacuuming. I'd say around 2/3 -3/4 volume and no issues with speakers or sony 1080. Good luck.
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post #17 of 32 Old 06-19-2019, 06:13 AM
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I run a 5.24 atmos setup with 5 4ohm speakers that are my bed channels that dip down to 3.7ohms which are B&W CWM7.3 in-walls. I run separates and just upgrade both of my amps to ATI AT527NC class D amps which replaced Rotel RMB-1585 class ab amps. The rotel amp is 200watts and the ATi amps are 300 watt my speakers call for 200watts the amp the extra headroom makes a huge difference in sound and clarity. The class d amps are much much more efficient. Before I had to crank my system from -22 to -18 now with the new amps -33to -28. My speakers are efficient as well, I think 90 or 92 sensitivity.
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post #18 of 32 Old 06-19-2019, 07:18 AM
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Get a separate amp for that for your L/R speakers at least. You can find used B&K amps for a good price for that purpose, or just get you something new. Amps last forever.
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post #19 of 32 Old 06-19-2019, 07:22 AM
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Quote:
Originally Posted by redgum11 View Post
A decent easy reference point, a capable 4 ohm amp should be rated pretty much exactly double its 8 ohm specs.
Not quite double, but close. Usually about a 75-90 percent increase.

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post #20 of 32 Old 06-19-2019, 09:39 AM
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Quote:
Originally Posted by Dave-T View Post
I run a 5.24 atmos setup with 5 4ohm speakers that are my bed channels that dip down to 3.7ohms which are B&W CWM7.3 in-walls. I run separates and just upgrade both of my amps to ATI AT527NC class D amps which replaced Rotel RMB-1585 class ab amps. The rotel amp is 200watts and the ATi amps are 300 watt my speakers call for 200watts the amp the extra headroom makes a huge difference in sound and clarity. The class d amps are much much more efficient. Before I had to crank my system from -22 to -18 now with the new amps -33to -28. My speakers are efficient as well, I think 90 or 92 sensitivity.

Your Rotel RMB-1585 has a published input sensitivity of 1.9V with RCA connections and 3.8v with XLR connections.

The ATI ATI527NC has a published input sensitivity 1.6v.

Using the same pre-amp or input voltage source on either unit would account for the difference in your volume level settings as the two amplifiers have different gain requirements. It has nothing to do with "head room".

If you level match the voltage gain of the input between the two amplifiers the volume settings would be displayed consistent. Another way to say this is that it takes less input voltage to drive the ATI to full power than it does the Rotel or the pre-amp you're using is not delivering sufficient input voltage to dive the Rotel to the same level until volume control is increased.

That does not necessarily mean that the Rotel is any less capable. The ATI has simply been designed to operate with a lower input voltage to reach full power. Since it takes a doubling of amplifier power to realize a 3dB increase in volume/SPL, the extra 100 watts that the ATI has will net you a 1.5dB gain in volume/SPL maximum with regards to "head room".
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post #21 of 32 Old 06-19-2019, 10:18 AM
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Originally Posted by b curry View Post
Your Rotel RMB-1585 has a published input sensitivity of 1.9V with RCA connections and 3.8v with XLR connections.

The ATI ATI527NC has a published input sensitivity 1.6v.

Using the same pre-amp or input voltage source on either unit would account for the difference in your volume level settings as the two amplifiers have different gain requirements. It has nothing to do with "head room".

If you level match the voltage gain of the input between the two amplifiers the volume settings would be displayed consistent. Another way to say this is that it takes less input voltage to drive the ATI to full power than it does the Rotel or the pre-amp you're using is not delivering sufficient input voltage to dive the Rotel to the same level until volume control is increased.

That does not necessarily mean that the Rotel is any less capable. The ATI has simply been designed to operate with a lower input voltage to reach full power. Since it takes a doubling of amplifier power to realize a 3dB increase in volume/SPL, the extra 100 watts that the ATI has will net you a 1.5dB gain in volume/SPL maximum with regards to "head room".
I used XLR’s on the both the Rotel and now the ATI amps. I always thought it had do with the efficacy of class Ab vs class D. Class D is typically around 90% efficient while ab is close to 50% so it takes more power to get the class ab amp to do what the class d amp can do. does the voltage of the xlr outputs on my Marantz 8805 come into play as well? it was also my understanding that 4ohm speakers are more difficult to push then 8ohm speakers and most AVR's can't handle or handle well 4ohm speakers in a home theater setup. I was always told separates are the way to go with 4ohm speakers. I typically Buy what I can afford and sounds good to my ears , alot of my gear is not purchased based on stats. Definitely sounds like you know more about the technical stuff than me.

Last edited by Dave-T; 06-19-2019 at 10:52 AM.
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post #22 of 32 Old 06-19-2019, 10:52 AM
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Quote:
Originally Posted by Dave-T View Post
Quote:
Originally Posted by b curry View Post
Your Rotel RMB-1585 has a published input sensitivity of 1.9V with RCA connections and 3.8v with XLR connections.

The ATI ATI527NC has a published input sensitivity 1.6v.

Using the same pre-amp or input voltage source on either unit would account for the difference in your volume level settings as the two amplifiers have different gain requirements. It has nothing to do with "head room".

If you level match the voltage gain of the input between the two amplifiers the volume settings would be displayed consistent. Another way to say this is that it takes less input voltage to drive the ATI to full power than it does the Rotel or the pre-amp you're using is not delivering sufficient input voltage to dive the Rotel to the same level until volume control is increased.

That does not necessarily mean that the Rotel is any less capable. The ATI has simply been designed to operate with a lower input voltage to reach full power. Since it takes a doubling of amplifier power to realize a 3dB increase in volume/SPL, the extra 100 watts that the ATI has will net you a 1.5dB gain in volume/SPL maximum with regards to "head room".
I used XLR’s on the both the Rotel and now the ATI amps. I always thought it had do with the efficacy of class Ab vs class D. Class D is typically around 90% efficient while ab is close to 50% so it takes more power to get the class ab amp to do what the class d amp can do. Then doesn’t the voltage of the xlr connection on the Marantz 8805 come into play as well?
The efficiency is a function of the conversion of energy from your power source (electricity) to the output of your amplifier. Class D has a higher efficiency than class A/B in this regard.

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post #23 of 32 Old 06-19-2019, 10:59 AM
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Originally Posted by jdlynch View Post
The efficiency is a function of the conversion of energy from your power source (electricity) to the output of your amplifier. Class D has a higher efficiency than class A/B in this regard.
If you don't have the necessary input voltage you can't drive it to full power regardless of class design. Blame Georg Ohm, I didn't make it up... It's his law.

Last edited by b curry; 06-19-2019 at 11:53 AM.
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post #24 of 32 Old 06-19-2019, 11:16 AM
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Originally Posted by Erod View Post
Get a separate amp for that for your L/R speakers at least. You can find used B&K amps for a good price for that purpose, or just get you something new. Amps last forever.
That's always a great suggestion, and with some receivers lets you run 11 channels ( like an X7200 ) instead of 9. I've used 4 ohm Martin Logan Motion speakers now since May 2013. First 9 channels, then 11 channels and now 13 channels ( with Denon 4520, X7200 and now an X8500 ). Never had a problem with the receiver powering the speakers, but get an Aircom T8 fan or similar to keep the receiver cool would be my suggestion. Of course I couldn't leave well enough alone, and I replaced my 2 channel Emotiva amp powering my left and right speakers with a Parasound Halo A 52+ amp to drive the W / L / C / R / W channels. More than enough power, and it sounds better than ever !
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post #25 of 32 Old 06-19-2019, 11:29 AM
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If you don't have the necessary input voltage you can drive it to full power regardless of class design. Blame Georg Ohm, I didn't make it up... It's his law.

At some point this statement will likely violate one or more of those bothersome thermodynamics/physic's laws. If true it will solve all our energy problems however. At the limit you are saying that 0V in will provide full output. It is doubtful that Ohm, Maxwell, Heaviside or anyone else proposed such a law.
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post #26 of 32 Old 06-19-2019, 11:51 AM
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Originally Posted by Dave-T View Post
I used XLR’s on the both the Rotel and now the ATI amps. I always thought it had do with the efficacy of class Ab vs class D. Class D is typically around 90% efficient while ab is close to 50% so it takes more power to get the class ab amp to do what the class d amp can do. does the voltage of the xlr outputs on my Marantz 8805 come into play as well? it was also my understanding that 4ohm speakers are more difficult to push then 8ohm speakers and most AVR's can't handle or handle well 4ohm speakers in a home theater setup. I was always told separates are the way to go with 4ohm speakers. I typically Buy what I can afford and sounds good to my ears , alot of my gear is not purchased based on stats. Definitely sounds like you know more about the technical stuff than me.
According to the published spec's, using XLR's on the Rotel requires a higher voltage. You should see a change in your volume control level if you switched to the RCA input on the Rotel. This is not unusual as XLR is more of an industrial connection were the balanced line is used to control EMI/RFI noise on longer cable runs. A higher voltage is typically used as well for consideration to gain structure for signal to noise ratio.

Again if you look at the specification's, the Rotel is rated at a maximum gain of 26.5dB. The ATI AT527NC is rated at 27.8dB maximum gain for a difference of 1.3dB between the two. The ATI has an input sensitivity of 1.6dB for full power on either RCA or XLR input where the Rotel is 1.9v on RCA and 3.8v on XLR.

The output voltage of the Marantz AV8805 is listed as Balanced XLR pre-output: 2.4v and Unbalanced RCA pre-output: 1.2v. So the Marantz AV8805 does not have the necessary voltage to drive the Rotel to full power on either input, RCA/XLR. With regards to the ATI, the Marantz is a little shy on the RCA and you would have to ability to overdrive on the XLR which could potentially cause some distortion.

I would not worry too much about it. You're typically only using watts in the fractions or single digits at normal listening levels anyway.

Speakers with lower resistance (4Ω) require, place a demand for more current for the amplifier to deliver the same voltage. Ohm's law. Separate power amplifiers generally have room for larger power supplies. Larger power supplies can provide more current. Most any name brand AVR can drive a 4Ω speaker. It's when it's called on to produce much higher volume levels where the amplifiers power supply is unable to supply adequate current and the voltage sags. The amplifier heats up as a result and the thermal protection kicks in and shuts the unit down. That's of course if the AVR has thermal protection. If this is done repeatably, components on the board will begin to fail.

FWIW, I run my backyard theater on an entry level Denon AVR E300. I use some older Polk Audio speakers that are 4Ω. I'm on a one acre lot and I've no problem generating sufficient sound to get the neighbors interested with it and it has never shut down from the speakers impedance load. Inside, I've some ridiculously high power amplifiers that never get used to their full power.

With regards to efficiency, less power is converted to heat and into usable "watts" in a class D vs. AB design. Because of the increased efficiency of class D, class D doesn't usually have the big heavy power supply transformer. With either class, you're only using the amount of power called for by the pre-amps input voltage relative to the speakers sensitivity and desired SPL.

Sorry to have intruded, but I hate to see so called "head room" get confused with a difference in input sensitivity when comparing amplifiers.
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post #27 of 32 Old 06-19-2019, 11:53 AM
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Originally Posted by bigguyca View Post
At some point this statement will likely violate one or more of those bothersome thermodynamics/physic's laws. If true it will solve all our energy problems however. At the limit you are saying that 0V in will provide full output. It is doubtful that Ohm, Maxwell, Heaviside or anyone else proposed such a law.
Woops! corrected.
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post #28 of 32 Old 06-19-2019, 12:13 PM
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That's always a great suggestion, and with some receivers lets you run 11 channels ( like an X7200 ) instead of 9. I've used 4 ohm Martin Logan Motion speakers now since May 2013. First 9 channels, then 11 channels and now 13 channels ( with Denon 4520, X7200 and now an X8500 ). Never had a problem with the receiver powering the speakers, but get an Aircom T8 fan or similar to keep the receiver cool would be my suggestion. Of course I couldn't leave well enough alone, and I replaced my 2 channel Emotiva amp powering my left and right speakers with a Parasound Halo A 52+ amp to drive the W / L / C / R / W channels. More than enough power, and it sounds better than ever !
It's a comfortable place to be....having too much power.

I've got 225 watts, five channels, all channels driven with my Anthem MCA525. Plus 125 watts, seven channels, two channels driven (I think) with my B&K Reference S2 125.7 amp.

If I used 60% of all that power at once, I'd blow my ears off. LOL

Unnecessary, but I unapologetically love it.
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Video: JVC RS620/X9500 projector, Stewart ST130 screen, Panasonic ub820 UHD player
Audio: Anthem AVM60 preamp, Anthem MCA525 amp, B&K Reference 125.7 amp
Subs: dual SVS PC-12 cylinders
Speakers: Jamo 626k4 in-wall mains, Jamo 631k4 bi/dipole surrounds, DefTech DI6.5R heights
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post #29 of 32 Old 06-19-2019, 12:35 PM
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Originally Posted by b curry View Post
According to the published spec's, using XLR's on the Rotel requires a higher voltage. You should see a change in your volume control level if you switched to the RCA input on the Rotel. This is not unusual as XLR is more of an industrial connection were the balanced line is used to control EMI/RFI noise on longer cable runs. A higher voltage is typically used as well for consideration to gain structure for signal to noise ratio.

Again if you look at the specification's, the Rotel is rated at a maximum gain of 26.5dB. The ATI AT527NC is rated at 27.8dB maximum gain for a difference of 1.3dB between the two. The ATI has an input sensitivity of 1.6dB for full power on either RCA or XLR input where the Rotel is 1.9v on RCA and 3.8v on XLR.

The output voltage of the Marantz AV8805 is listed as Balanced XLR pre-output: 2.4v and Unbalanced RCA pre-output: 1.2v. So the Marantz AV8805 does not have the necessary voltage to drive the Rotel to full power on either input, RCA/XLR. With regards to the ATI, the Marantz is a little shy on the RCA and you would have to ability to overdrive on the XLR which could potentially cause some distortion.

I would not worry too much about it. You're typically only using watts in the fractions or single digits at normal listening levels anyway.

Speakers with lower resistance (4Ω) require, place a demand for more current for the amplifier to deliver the same voltage. Ohm's law. Separate power amplifiers generally have room for larger power supplies. Larger power supplies can provide more current. Most any name brand AVR can drive a 4Ω speaker. It's when it's called on to produce much higher volume levels where the amplifiers power supply is unable to supply adequate current and the voltage sags. The amplifier heats up as a result and the thermal protection kicks in and shuts the unit down. That's of course if the AVR has thermal protection. If this is done repeatably, components on the board will begin to fail.

FWIW, I run my backyard theater on an entry level Denon AVR E300. I use some older Polk Audio speakers that are 4Ω. I'm on a one acre lot and I've no problem generating sufficient sound to get the neighbors interested with it and it has never shut down from the speakers impedance load. Inside, I've some ridiculously high power amplifiers that never get used to their full power.

With regards to efficiency, less power is converted to heat and into usable "watts" in a class D vs. AB design. Because of the increased efficiency of class D, class D doesn't usually have the big heavy power supply transformer. With either class, you're only using the amount of power called for by the pre-amps input voltage relative to the speakers sensitivity and desired SPL.

Sorry to have intruded, but I hate to see so called "head room" get confused with a difference in input sensitivity when comparing amplifiers.
This is stuff that confuses me. I no longer have the Rotel amp, I sold it. I have two ATI AT527NC amps. I do not play my setup loud at all I live in a condo. I wanted new amps because the Rotel was literally a space heater. So will XLR’s cause damage to my amps or processor because the voltage does not match up? Distortion can cause issues and damage to speakers or amps right? or am I only looking at problems if I crank my setup at blistering volumes? For subs I use to JL F112v2 subs with XLR’s as well.
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post #30 of 32 Old 06-19-2019, 02:16 PM
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Originally Posted by Dave-T View Post
This is stuff that confuses me. I no longer have the Rotel amp, I sold it. I have two ATI AT527NC amps. I do not play my setup loud at all I live in a condo. I wanted new amps because the Rotel was literally a space heater. So will XLR’s cause damage to my amps or processor because the voltage does not match up? Distortion can cause issues and damage to speakers or amps right? or am I only looking at problems if I crank my setup at blistering volumes? For subs I use to JL F112v2 subs with XLR’s as well.
The JL Audio subs use their own internal amplifiers.

Like I said, don't worry about it. The Marantz input voltage does have the capability to over drive the ATI. But you're likely not going to get there. You're not going to go to 11 on the dial.
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