Please explain "high Current" receivers....

Discussion in 'Archived Threads 2001-2004' started by jeff morris, Mar 30, 2002.

  1. jeff morris

    jeff morris Agent

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    Hello all-
    Can someone please explain the benefits of "high current" receivers. I see that some manufacturers offer this and others don't.
    I am particularly interested in the new Onkyo 500/600 Rx's coming soon and I was concerned about the wattage outputs, feeling that more is better(headroom and all that) but not sure that a $200 difference is worth it. My friend sez that the 500 (60w/ch) should be more that adequate in my room because of the high current amp design.
    thanks for the help [​IMG]
     
  2. Selden Ball

    Selden Ball Second Unit

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    Selden
    "High Current" is usually marketing double speak which means that the amp can put out a reasonable amount of current into low impedance loads. Many inexpensive receivers actually supply less power when they have to drive 4 Ohm speakers than when they drive 8 Ohm speakers. Their power supplies and output drivers are current-limited to keep the design cost down. High current amplifier designs should be able to supply more current into the lower impedance loads.

    When you use a low power receiver, it's important that you get high sensitivity speakers. Every 3dB of increased efficiency in the speakers is equivalent to doubling the amplifier power.

    I hope this helps a little.
     
  3. jeff morris

    jeff morris Agent

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    Thanks Selden,
    Your reply makes perferct sense as far as current limiting with low impedance spkrs.
    I am currently using an old, original Technics 5 channel Dolby pro logic RX with Baby Advents as my mains, which are rated at 4 ohms. This probably explains why my RX cuts out when I crank up the volume on ANY material - goes into thermal overload I'll bet.
    So I guess the high current Onkyo would help my situation of 4ohm fronts and 8 ohm rears.
    My other question would be to ask, would the 60w/ch be enough? I eventually plan on moving the advents upstairs and getting another pair of Polk Rt25's to replace them with- they are my present rear speakers.
    thanx[​IMG]
     
  4. Paul Clarke

    Paul Clarke Supporting Actor

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    Depends on the size of your listening space and how loud you like your sound levels.

    Example: I just got an H/K 310 for the bedroom system. I unhooked my H/K 510 from the main system and slipped the 310 into it's place for testing. The 310 is 60 x 2 and 50 x 5. Front towers are 6 Ohm (88dB) and the rest is 6 Ohm 89dB.

    Aside from having to go a little higher on the loud dial, there is really no difference than with the 80 x 2 and 70 x 5 510. The 5 just has more beans. Admittedly, 4 Ohm speakers represent more of a challenge than my 6's but I have never suffered any heat problems and my cabinet only allows 1.5"s of venting space (open front and back).

    You should be fine.
     
  5. Peter Johnson

    Peter Johnson Stunt Coordinator

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    Its a marketing term.

    An amp should act like a pure voltage source, meaning that the current drawn is dictated entirely by the load...which will vary with frequency.

    Some recievers will be able to output more current than others..bigger power supplies, and more powerful output devices etc will do this. But unless your speakers require this current (which requires a large power draw into a low impedence load), its overkill.

    The problem is, what defines "high-current design". The answer is nothing. Some manufactures of crappy $300 recievers claim it, and a high-end manufacturer of a cost-no-object power amp might not even mention it. Its a marketing term...in every sense of the word.
     
  6. John Sully

    John Sully Stunt Coordinator

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    The price range you are looking at is very competitive and showing big(ger) watts on the spec sheet is important from a marketing point of view. I recently looked at a spec sheet for the new Onkyo Integra 6.3/5.3 and found a *very* suspicous power rating there. The claims were for 110(6.3) and 100(5.3) 20-20kHz, FTC. No distortion level was spec'd, this is not compliant with the FTC method of stating power. The FTC method also only requires that 2 channels be driven, so I seriously doubt that these "premium" versions of the 600/500 will actually produce the claimed power with all channels driven.

    The problems with the way the 500/600 are spec'd runs even deeper. Now I am not ragging on Onkyo products. My first A/V receiver was an Onkyo 767 and it was a *very* nice unit and Onkyo has traditionally been one of the better manufacturers of electronics. Rather this is just a caveat emptor when looking at power ratings for lower end receivers. Ever wonder why most manufacturer's flagship receivers only make 20/wpc or so more than their low end receivers? It's because the flagships can actually produced their claimed power with all channels driven. It is about time that the FTC stepped in a put an end to this nonesense by requiring that A/V amps be spec'd with all channels driven, just like the previous FTC spec for stereo amps required.

    If you have efficient speakers (~90db/2,83V/1m) and a small room, you should be OK with the 600, although I would be surprised if it can produce 50/wpc into 8 ohms all channels driven. If you have a large room or slightly less efficient speakers fergit about it, you won't be happy with one of the lower end receivers.
    This is just my opinion, I could be wrong...
     
  7. Arthur S

    Arthur S Cinematographer

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    Jeff

    In the November Consumer 2001 Reports test of receivers, only 3 receivers could deliver significant wattage to 4 ohm loads 2 were Yamahas, one Sony (STR-DE 675).

    Onkyo 676, while rated tops overall delivered (2 channel) 131 into 8 ohms, 147 into 6 ohms, and 63 watts into 4 ohms.

    If high current into 4 ohms was my top criteria, I would have to look seriously at Yamaha.

    Artie
     
  8. MatthewJ S

    MatthewJ S Supporting Actor

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    It used to be thought that across the board Yamaha , Denon, Sony ES, HK, and Onkyo all had "high current " amp designs .

    However , as many of these lines have started to show up in mass market retailers whose sales were an obnoxiously large %age of their buisness ,these retailers put pressure on the mnfgrs to beef-up the wattage #'s, add features but still keep the costs in the range of cheaper gear...How do they do that, you ask? Good question.....When a speaker or rcvr manufacturer gets 80+% of its buisness from one retail chain ,usually they are dictating much of how the gear is made and what it must retail for.......When they keep adding features and reducing the price it is usually that intangible thing called amp quality that suffers.....You can't get a good demo of sound quality at most CC'S or BB's
     
  9. matthew_rm

    matthew_rm Second Unit

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    It's not all marketing. However, most of the time it is. HK actully have high current recievers. Their 2ch recievers put out over 42 amps/p/ch!!!
     
  10. Peter Johnson

    Peter Johnson Stunt Coordinator

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  11. Aslam Imran

    Aslam Imran Second Unit

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  12. matthew_rm

    matthew_rm Second Unit

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    Oh
     
  13. Fredrik E

    Fredrik E Stunt Coordinator

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  14. matthew_rm

    matthew_rm Second Unit

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    So was I right before?
     
  15. Craig_Kg

    Craig_Kg Supporting Actor

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  16. EdS

    EdS Agent

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    Even if the impedance is only 1 ohm, it still calculates out to putting out 882W, even if only briefly. I've never seen any test data to support that any receiver (or most amps for that matter) can output this can kind of power, even for a short period of time.

    I think that HK's claim of "high current" amplifiers is more marketing than a universally accepted measurement. There are tests for short term output power, I think that the typical time duration is 100 ms. At best, I think that HK's claim of 42A probably means that the amplifier components are rated to handle 42A, which doesn't necessarily mean that the amp can output 42A. Since HK is making the claim, they should be able to specify under what conditions the amp could output 42A (size of load, time duration, frequency, etc.)
     
  17. MarkO

    MarkO Second Unit

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    It may be marketing on h/k's part, but at least they back it up through some of the highest quality mass market intergrated amps on the market IMO. Many times under rating thier equipment.
     
  18. Paul Clarke

    Paul Clarke Supporting Actor

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    Precisely. Just look at one aspect of various popular competitive receivers: weight.

    Yamaha 620 weighs 23lbs and claims 100X5 watts.

    Denon 1802 weighs 24lbs and claims 80X5 watts

    Marantz 5200 weighs 28lbs and claims 85x5 watts.

    Harman Kardon 320 weighs 32lbs and claims 55x5 watts.

    Outlaw 1050 weighs 36lbs and claims 65x5 watts.

    Now these are 8 Ohm listings and part of this discussion centers on 4 Ohm loads but all of the above are 4 Ohm capable.

    Hmmmmm. I wonder which of these examples is closer to anything approaching truth? And of the (hint) two which are I wonder which one bases it's claim on all channels driven? Any guesses?

    Enough sarcasm. This is not to pick on any of the aforementioned equipment. I happen to like all of them regardless of the marketing ploys used. But common sense tells us that some of these manufacturers are not loading their equipment with lead feet. Figure it out for yourself.

    The H/K receivers equal or best their power ratings claims whenever they are tested...and they do so with clean sound. There is always a price for this kind of truth in advertising.
     
  19. Craig_Kg

    Craig_Kg Supporting Actor

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  20. MatthewJ S

    MatthewJ S Supporting Actor

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    I never understand why people keep bringing up the "weight" issue over and over again...there are sooooo many differant types of power supplies, that have such vast differances in efficiancy (and cost) that the weight of the unit, while hopefully is an indicator of build quality and quality of the power supply , isn't neccesarily so...I have seen many large innefficiant power supplies and many small efficiant ones doing the same job...do you wan't to guess which one costs more? that's right the smaller, lighter one...and companies being driven often by market research often use larger heat sinks and cheaper heavier power supplys just to get the weight up.....
     

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