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AVR300 4/8 Ohm Switch

Discussion in 'Arcam Owners' Forum' started by ntang, Sep 7, 2005.

  1. ntang

    ntang
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    Hi

    Maybe someone could shed some light on this for me. I recently purchased the AVR300 and the manual says that 8 Ohm is at the bottom position of the switch while 4Ohm is at the top position...as illustrated in said manual.

    However, my actual unit has it reversed, 8ohm at the top, 4ohm at the bottom and it came out of the box in the bottom position.

    Since my speakers are 8 ohm, I have disregarded the manual and followed the way the switch is laid out on the unit itself and flipped it up to what the unit says is 8Ohm

    Can someone tell if if perhaps I have a wrongly assmbled/printed unit? I am not an expert in electronics and this has been bugging me for a while. I have not tried it at the 4ohm position on the unit.

    Furthermore, I find the unit running quite hot...maybe normal but I am not sure since this is the fisrt Arcam I own

    Pls advise

    Thanks

    /Nick
     
  2. johndon

    johndon
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    The manual is, I believe, printed incorrectly and the switch on the back of the unit is correct.

    John
     
  3. Diggin4fire

    Diggin4fire
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    I also went through a lot of confusion as to the position of the button!
    If I remember correctly: Somewhere in this forum Mr. Dutton explained to an AVR300 owner that using the 4 Ohm switch is possible even with 8 Ohm speakers. The gist of it was - I think - that his system would run less hot, and his sound would change (maybe even improve).
    I have tried it myself, and the effects were as promised. My sound actually improved slightly. Don't know how much more electricity it will use, but it's certainly worth it.
     
  4. johndon

    johndon
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    My speakers are rated at 8ohm and my dealer recommended setting the switch to 4ohm.

    John
     
  5. John P.

    John P.
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    I've been reading up a little on this, because I have been thinking lately that perhaps the 4Ohm/8Ohm setting could be what caused my AVR300 to misbehave. My speakers are rated 6Ohm, and I had the switch set to 8Ohm.

    Now - I have read just now, that in one test(AVTECH), the unit delivered 115W pr. channel all channels driven into 8Ohm. But: only 42W pr. channel all channels driven into 4Ohms!

    I then read that if the Ohm switch was set to 4Ohm, the unit would deliver 80W x7 @ 8Ohm, and 120W x7 @ 4Ohm!

    (numbers may not be 100% correct, I'm taking it from memory)


    This is not a link to that test, but I think the figures show some of the same things(they probably had it in the 8Ohm setting): [LINK]

    Based on this, I read that someone recommends setting it in the 4Ohm setting no matter what.

    But - I then read a general note about these 4Ohm/8Ohm switches somewhere else:
    http://www.audioholics.com/techtips/buyingguides/avhardware/receivers.php#im

    Reading this, it seems the 8Ohm setting is the best no matter what (pretty much)...


    So I'm still a little confused.
     
  6. cwick

    cwick
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    John,

    I'm pretty sure that one of the Arcam employees posted, a while back, that the AVTECH results were based on a pre-production unit, and the numbers they published weren't valid for production units ... I'll see if I can find the thread.


    Cheers, Carl.
     
  7. John P.

    John P.
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    OK, thanks.

    But what would people recommend then for me when I get the receiver back from repair? With my 6Ohm rated speakers, should I flip the switch to 4Ohms?
     
  8. cwick

    cwick
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    Based on posts by ANDY_DUTTON, you should switch it to 4 ohms.
     
  9. hedrick@rutgers

    hedrick@rutgers
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  10. Crustyloafer

    Crustyloafer
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    I run mine in 4 ohm mode. I believe this give the unit a higher tolerance of difficult loads at the slight expense of a reduce overall maximum avilable volume. Now given that most modern loudspeakers that are rated as 8 ohm loads actuall have a hugely varying impedance relative to the frequency they are reproducing it would make sense to run the AVR250/300 in 4 ohm mode and made it easier on the unit and less likely to overheat.

    A very good examply of a very common and popular range of speakers that many use with the Acam receivers are the B&W 600 S3 range. Below are details of each speaker's rated impedance and their lowest impedence presented to the amplifier.

    B&W DM600S3: Normal impedence: 8 ohms Minimum impedence: 3 ohms

    B&W DM601S3: Normal impedence: 8 ohms Minimum impedence: 3 ohms

    B&W DM602S3: Normal impedence: 8 ohms Minimum impedence: 3 ohms

    B&W DM602.5S3: Normal impedence: 8 ohms Minimum impedence: 3 ohms

    B&W DM603S3: Normal impedence: 8 ohms Minimum impedence: 3 ohms

    B&W DM604S3: Normal impedence: 8 ohms Minimum impedence: 3 ohms

    B&W DS6S3: Normal impedence: 8 ohms Minimum impedence: 3.3 ohms

    B&W CDS6S3: Normal impedence: 8 ohms Minimum impedence: 3 .3 ohms
     
  11. cjohnson6

    cjohnson6
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    As mentioned earlier in this thread, most amps are designed so that switching to 4 ohms reduces the supply rail voltage. This is done to protect the output stage. What's not confirmed anywhere here is which position is 4 ohms and which is 8 ohms. One way to find out is to open up the unit and stick a voltmeter across the storage caps.

    Anyone game for this?
     
  12. Crustyloafer

    Crustyloafer
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    The printing on the back of the amp is correct, the misprint is in the manual.
     
  13. cjohnson6

    cjohnson6
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    That's good news and what I would have expected.

    No need to invalidate the warranty!
     

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