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m&k help

Discussion in 'Home Cinema Speakers' started by mark bessant, Aug 11, 2005.

  1. mark bessant

    mark bessant
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    hi everyone, this is my second time on this site so be gentle with me. im very new to home entertainment and i have just spent alot of money on some expensive equipment and have come accross a big problem. and hopefully someone could give me some good advice on what to do!

    i have bought a pioneer vsx-ax5i amp and a set of m&k speakers, 3 x kx7, and 4 x kx4 tripole speakers for the rear. the problem i have is that all seven speakers there impedance is only 4 ohms and speaking to pioneer yesterday they told me that it is not a good idea to run these speakers on this amp, if i turn the sound up that it would trip the amp and maybe damage the speakers reding the pioneer amp manual you can change the speaker impedance to either 6 ohms, 8 ohms, or 16 ohms in the programming, so if i programme it will this work o.k

    i thought that all small satalite speakers were basiclly the same ,

    has this been a very expensive mistake or is there another answer :suicide: .

    cheers
    mark b
     
  2. recruit

    recruit
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    Hello Mark,
    Could i just ask did you buy all you're equipment from the same dealer and if so were they not adviseing and helping you choose the equipment?

    I am not trying to sound negative but it should be there responsibility if something goes wrong.

    My friend at work runs the M&K 851 speakers thru a denon 3805 and they run fine and even at high levels, yes the amp gets hot but that does happen with most amps anyway.

    I would speak to you're dealer 1st and go from there, but i think you should be ok as the Pioneer is a good amp and quite powerful too.

    Regards
    John
     
  3. mark bessant

    mark bessant
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    thank john for a quick reply i brought the speakers for the us as they were £1000 cheaper than the uk and i brought the amp from hifi confidential but i did not know what speakers i was going to use .

    cheers mark b
     
  4. Ian J

    Ian J
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    I've heard stories that Pioneer amps and M&K speakers don't go too well together which is surprising as the VSX-AX5i is supposed to be THX certified but perhaps the THX logo on hardware doesn't mean much anymore.
     
  5. recruit

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    I would have to agree with Ian on that, Pioneer amps are considered to be quite bright sounding amps and add M&K speakers to it and that will only enhance that even further. :(
     
  6. Smurfin

    Smurfin
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    I think as Recruit says it's got more to do with sound characteristics than anything else. I would be wary of partnering those 2 in a bright sounding room, but it may be ok. Get a demo if you can:)
     
  7. mark bessant

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    mybe then i should sell my amp and get a new one but what one should i go for some think that can run 4omhs with no problems.

    cheers mark b
     
  8. recruit

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    Well done on getting the M&K's cheaper, the only thing i could say would either give them a go and see how it works out or if it doesn't either change the speakers or amp, i know it is not what you want to hear but give them a try and you might be happy.

    All the best
    John
     
  9. mark bessant

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    thanks for your advice john i will give the amp a go if it is not to my likeing i will have to get rid of it .

    regardes mark b
     
  10. Ian J

    Ian J
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    I was referring to the stories that the Pioneer amps weren't recommended for driving 4 ohm speakers
     
  11. ufitsy

    ufitsy
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    Am I right in saying that this should not be confused with the newer VSX-AX5AI-s which has a higher output?
     
  12. Joe Fernand

    Joe Fernand
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    Hello mark

    Seems odd to go to all that trouble to import speakers from the US if 'all small satalite speakers were basiclly the same'!!!

    The suitability (or not) of the VSX-AX5Ai is as Pioneer UK and IanJ point out down to how well it will interact with loudspeakers presenting a 4 ohm load - if Pioneer UK advise you against using the AV Receiver with these speakers its prudent to consider an alternative AV Receiver or Power Amp and not risk damage to the Loudspeakers and or AV Receiver.

    Very few AV Receivers are engineered to work with 4 ohm loudspeakers - the Arcam DiVA AVR-250 and AVR-300 both have back panel switches that allow you to set the AV Receiver for use with 4 ohm loudspeakers.

    See http://www.arcam.co.uk

    If you do stick with the Pioneer AV Receiver for now then ensure you don't try and operate the system at very high volumes - though as IanJ points out the VSX-AX5ai has a pretty efficient safety mechanism which is likely to jump in before you damage anything in your system.

    Best regards

    Joe
     
  13. Smurfin

    Smurfin
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    This talk of Pioneer's struggling with 4ohm loads is - imho - a bit of a red-herring: if you do a search you'll find plenty of people running 4ohm speakers with Pioneer amps and having no problems.

    Bottom line is...you need to try to get a demo and then you can see how it all fits. So many other factors come into play, such as room size and preferred listening levels. If you like movies loud then have a demo and crank it, you'll soon notice if the sound hardens up and the "brightness" if there is any present will become quite pronounced.

    re: the AX5Ai....I believe this has the same power supply as the AX5i, AX5 and 2011, and although Pioneer may quote a higher power output, if the power supply is the same I don't believe the real world output would be any different (I stand to be corrected if anyone else knows different though :) )
     
  14. Andywilliams

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    Hi Mark
    Nad receivers would drive the m&ks with no problems they have very good power supplys and are designed to cope with 4ohm loads (no switches) they also sound more on the smooth side so sound good with m&k. I used to run a nad t752 receiver with my m&k 850s at very high volumes with no probs at all . :)
     
  15. Sniper

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    no switches - THE ONLY WAY IT SHOULD BE! Switches are for cheating!
     
  16. recruit

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    Also other amps to look at would be the Harmon Kardon range which use big amps with lots of current and would not have any problems running M&K speakers.
     
  17. Joe Fernand

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    Hello smurfin

    Believing in Red Herrings and offering to cover the cost of a set of replacement drivers for five M&K Satellite speakers are not one and the same thing!

    The VSX-AX5ai User Manual and Pioneer UK tech support advise that this AV Receiver should be used with loudspeakers having a nominal impedance of 6-8 ohms - if your using 6 ohm speakers you have to set a dip switch on the rear of the AV Receiver.

    Again I'd suggest a 4 ohm compatible AV Receiver or an additional Five channel power amp for use with the M&K satellite speakers.

    Best regards

    Joe
     
  18. Joe Fernand

    Joe Fernand
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    Sniper

    I take it the likes of Audio Note, Krell, Levinson, Conrad-Johnson etc must all be 'cheating' when they provide either separate taps or switched outputs for 8 or 4 ohm operation on many products - you'd think on these ultra high end amplifiers they would get it right :)

    Best regards

    Joe
     
  19. Andywilliams

    Andywilliams
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    To be fair Joe sniper and myself were talking about amps round the price of a denon 3805 the budget amps use a different technology to the hi-end variety. :)
     
  20. Joe Fernand

    Joe Fernand
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    Hi gonzo

    OK; I was being harsh! As you say different technology - though worth noting the AVR-3805 is not ideal with 4 ohms either :)

    Joe
     
  21. Nic Rhodes

    Nic Rhodes
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    nothing wrong with a switch or tap for 4 even at these prices, loads of examples at home ;).

    Why not look at external power amps to drive the MKs? You could use three amps for the bass units of L, C and r, use the receiver to biamp L, C and R and drive the rears and sides. Set all the speakers to small, this could be a happy medium between buying all new kit and keeping loads on amps down to reasonable level. It would also allow a SQ upgrade!!
     
  22. Joe Fernand

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    Hello Nic

    As you say nothing wrong with switched outputs for 4 ohm use - and I guess some would say its beneficial if the design of the amp stage in the AV Receiver is such that it sounds best with 8 ohm speakers when the 4 ohm circuitry is not in play.

    Best regards

    Joe

    PS Small, Ultra Efficient, 4 ohm friendly mono block power amps available here - http://www.avforums.com/forums/showthread.php?t=234267&goto=newpost
     
  23. mark bessant

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    thanks you guys for your input on this matter i just got home from work and have found a email from m&k he basicley said that some m&k speakers might actually be somewhat too conservatively rated. they are not "just4 ohms they might drop down to 4 ohma at some frequency. so it might be accurately stated that "nominally" they are 6 ohms . and as far as amp go most very high end products (often separates) such as krell and mark levinson and a few others typically do accurately slate their amps rated power . many consumer-grade devices don't unfortunately. therefore if you have an amp which is rated for thx uitra that amp is supposed to deliver a certain rated power into 3.2 ohms which certainly means it should drive "4" ohm speakers if it doesn't then that is aproblem which must be taken up with the amp manufacturer or thx or both.thats what he said the senior audio support engineer. cheers mark b
     
  24. recruit

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    Let us know how you get on Mark and whether the Pioneer & M&K work.

    Good Luck :thumbsup:

    John
     
  25. psflynn

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    im just jealous. I had to buy all second hand to get my m&k system!!! but it is absolutely superb!

    How much do the extra pair of k4s add to the equation? In my opinion (albeit fairly small room (single garage size) the single k4 surrounds work superbly!
     
  26. Sniper

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    Joe - you have to consider (as Gonzo pointed out) that the amps we were discussing are in a different league to the ones you mentioned. Having said that, I have to admit I was not aware that high-end brands such as the ones you mentioned had the need for such a switch.

    Would you be able to let us know what this switch really does on those amps. I just can't imagine why a cost-no-issue psu will need to "know" what load it's driving. Just curious.

    Cheers
     
  27. Joe Fernand

    Joe Fernand
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    Hello Sniper

    I'm no electrical engineer - we need Nic (Rhodes) to jump in here :)

    The Output Taps (often 4, 8 and 16 ohm) on the high end kit (especially so Valve kit) are more about audio quality than safety.

    On the AV Receivers being discussed the 4ohm switch introduces circuitry and limits to the Output stage to ensure the amp doesn't exceed pre defined operational temperatures when driving 4 ohm loads - in the 8 ohm position you can overheat the AV Receiver.

    The AV Receivers that say don't go below 6 ohms cant meet all of the requirements laid out by US safety folk to ensure you don't over cook them and cause any resulting hazards!!!

    Apologies for being so vague.

    Joe
     
  28. Nic Rhodes

    Nic Rhodes
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    The are two basic amplifing componets, transistors and valves. One is good at voltage amplification and one is good at current amplification.

    Valves are inherently more stable / linear devices and they are therefore the amplifiers are easier to make. This is why I make them ;) To get a stable low distortion circuit they need minimal amounts if any feedback to make the devices stable. The output transformer 'matches' the impedance of the transformer with the impedence of the speaker. This maximises the amount of power transfered. i.e and 8 ohm tapping on a transformer puts the most power into an 8 ohm loudspeaker. Other tapping will also work but they are much less efficient power transmission wise. If you therefore have a speaker that is fairly flat 8 ohms valves amps work very well. If you have a speaker with huge dips in the impendence curve (say down to 3/4) then valve amps don't work very well. A 4 ohm tap will say yield 50w, the 8 ohm tap will also give 50w as will the 16 ohms etc etc.

    Transistors are much less linear and are more difficult to make stable without the use of feedback. Basically every transistor amplifier uses this. Expensive amplifiers have special circuits that continuously monitor this and adjust the amplifier accordingly. i.e the dip and swing of speaker impedences and adjust amplifier varable accordingly. This does add considerably to the cost however. Most amplifier can't afford to spend this extra money however and have the quantity of feed back targetted at 6/ 8 ohm loudspeaker. If 4 ohm speakers are connected the amplifier has to work MUCH harder and this changes the feedback, this changes the operating point of the amplifier, making it work even harder. The feedback litterally takes a small amount of the output and puts it to another part of the circuit. Increase the output, and you also increase the feedback. The effects the stabilty of the amplifier. Don't forget transistor amplifiers need feedback to make the stable unlike their valves counterparts. [This is stability and we are not talking about the effect fb has on sound quality here]. Changing the feedback changes the stability. A simple switch adjusting the feed back to aim at 4 ohms rather than 8 is therefore a switch and resistor only. It is therefore very cheap and has a significant effect on the stabilty of the amplifier. In a perfect transistor amplier you will get 50w in 8 ohm, 100w into 4 ohm, 200w into 2 ohm. They are therefore better able to drive speakers with dips and swing in the impence curve. However most amplifiers we use in AV rarely achieve anything like this because of the stabilty of the circuit and the power supply used. Typically with 50w into 8 ohm, 75w into 4 ohm and perhap 95w into 2 ohm for short bursts only. The PS cannot supply yield the extra power and the circuit is 'loosing' it's stabilty. If this happens the amplifier will activate it safety circuits and shut down.

    Valves amps however are 50w into 8ohm, 50w into 4, ohm, 50w into 2 ohm. The only difference is the ouput taps on the tranformer. [different number of windings]. In theory the they could drive a 2ohm louspeaker with ease where as transistor would struggle unless feedback was adjusted accordingly. However luckily we don't have 2 ohm loudspeakers (anymore) but we have 8 or 4 ohm loudspeakers that the impedence dips to 2 ohms. This is a killer for valves but transistor might be able to cope! Hope that makes sense!

    Switches on transistor amplifiers adjusting the amplifier parameters for different impedence speakers is therefore a good idea. There are better ways of doing it however. It is good value sensible solution but it is not the best technical soluytion. Different taps on a valve amplifier are essential however and multiple taps is generally a sign of quality and the best way to do it.

    Hope that explains things without getting too boring / technical ;)
     
  29. Nic Rhodes

    Nic Rhodes
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    as most power is in the bass area I suggested earlier that speker are run as small (leave it to the sub) and use a separate amplifier for the lower frequencies (woofers)on the three channels with the most power requirements (L, Cand R) (biampng). The 4 ohm speakers will present a minimal load to the amplifiers now and chances are they are are actually much higher than 4 ohm in the frequencies they are now operating in.
     
  30. Joe Fernand

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    Hello Nic

    Glad I didn't attempt that explanation!

    M&K only produce Main 'Satellite' speakers (plus active subs) so the K-7 and K-4 speakers should be set to 'small' in any system.

    As you suggest an additional 4 ohm tolerant power amp or a different Receiver would be preferable to using the Pioneer AV Receiver and possibly running into operational problems.

    Best regards

    Joe

    PS When do we see the launch of the 'Nic Rhodes' series Valve amps then?
     

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