Does Pioneer SCLX85 have 4ohm mode?

Discussion in 'AV Receivers & Amplifiers' started by Bish, Feb 6, 2014.

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  1. Bish

    Bish
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    Guys, looking for some kind of clarification on this should anyone know?

    I've had the 85 since release and have just purchased some M&K MP150mk2, which are 4ohm.

    Pioneer list the following statement on their website against the LX86, which obviously was the natural 12month buff up of my 85. In the spec sheet there is also a tick against "4ohm speaker support"

    They say:

    "4 Ohm speakers now support higher levels of power to provide you with breath-taking, jaw-dropping audio perfection. For the first time, Class D level amplification comes with 4-Ohm speaker support"

    I'm assuming the LX85 is similar?

    Thanks
     
  2. dante01

    dante01
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    ohms are an indication of the impedance imposed by speakers and not something you can equate to the power output of an AV receiver. Amplifiers are not rated in terms of ohms, but in terms of wattage. The wattage rating will differ in relation to the impedance imposed upon them so the wattage output is roughly double what it would be in relation of 8 ohm speakers when powering 4 ohm speakers. The lower the impedance of your speakers then the less resistance they are to the powwr supply, but this can cause an amplifier to struggle while trying to keep up with the demand for the faster flowing current. LOwer end AV receivers tend not to be suitable for use with low impedance speakers, but most higher end products have better power supplies that can cope with the additional demands of low impedance speakers.


    There's no such thing as a 4, 6 or 8 ohm amplifier, but there are amps that can and cannot cope with low impedance loads. Impedance is something used to rate the device being powered and not the device doing the powering.


    Your receiver isn't rated for use with 4 ohm speakers which suggests it inadvisable you power 4 ohm speakers with it. You run the risk of damaging the receiver if power low impedance loads with it. You'd need the LX86 with its improved power supply and revised amplification stages.
     
    Last edited: Feb 6, 2014
  3. Bish

    Bish
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    Dante01, appreciate the time taken to document that, and your knowledge is clearly way above my own on this subject. You make the point about Low end v High end receivers. I think the general vibe out there is that the LX85 is still Pioneers best receiver to date and was their flagship model. I would consider it "high end" no?

    I'd read that the LX86 was a bit of a "miss fire" for Pio and many preferred the 85....Not sure what the vibe is for the current 87 model.

    Again, appreciate comments and I'm unexpectedly concerned that I may need to swap the receiver now.

    Further investigation required.
     
  4. dante01

    dante01
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    Maybe consider contacting Pioneer directly and asking them as to whether they advise against using 4 ohm speakers with the receiver?
     
  5. PC Nut

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    Being the best amp at time of production (I agree) doesn't make it suitable for use with all speaker types as dante01 mentions, serious damage will occur if driven to any sort of volume level and my even kill the amp at switch on.
     
  6. Philip4242

    Philip4242
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    I can't disagree with that, but you'd probably run into unacceptable distortion before any damage would actually occur.

    Please explain exactly WHY that might happen !!!

    It may well have been true many years ago (before the advent of speakers being disconnected by relays while the amplifier power supplies stabilised) - but on a modern amplifier ?!?
     
  7. dante01

    dante01
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    Most if not all AV receivers now incorporate protection circuitry that would go a long way to prevent major damage from being inflicted, but this circuitry isn't 100% fail safe. Damage is more likely to occur over a period of time as the amp gets hotter and at higher volume levels. The receiver's protection circuitry would cut the power to the amplification stages as soon as abnormal temperature rises are detected and the receiver would be forced into protection mode. Even though protection circuitry is employed it is still not desirable to have your amp shut itself down every time you edge the volume up. Driving low impedance speakers with an amp not rated as being suitable will in all probability trip the protection circuitry into action far more often than is desirable and at quite moderate volume levels. Even if the amp lives on then the excess heat will shorten its life and cause undue deteriation to the solder on its circuit boards and or shorten the life of capacitors not rated for the higher temperatures being experienced.
     
  8. Bish

    Bish
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    Appreciate the comments here. I spoke with Pioneer HQ today about this and the facts are - according to them. Unlike the 86/87 the 85 wasn't designed to power 4 ohm speakers - but it can, and it'll not hurt it. I may experience problems playing music exceptionally loud for exceptionally long periods of time, but the amp has adequate protection to shut down should it feel it's working too hard. I also agree with the above comments, that it's not advisable to let this happen 10 times a day for 2 years, and I can't imagine any genuine av fan who knows a bit about what they are doing would let this happen any now. The other interesting point raised in another forum was the fact that both the amp and speakers are THX Ultra 2 certified so it should be overly dangerous. Either way, I want more power and I want to be driving my mk's to the full so I going after a new Pio87 or the Anthem 710.
     

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