What two channel amp to buy and how much power?

Discussion in 'AV Receivers' started by Matt LB, Aug 14, 2003.

  1. Matt LB

    Matt LB Auditioning

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    As said in another post, I am going to purchase a 2-channel amp to add on (for my front mains) to my HK avr 520 so that I can do 7.1 My speakers can handle a max of 400w...how big of an amp should I use. I really don't want to spend over $500 for it...probably purchase it on ebay. I was looking at some of the carver tfm-25 or tfm-35. I guess i'm just trying to figure out how much louder and cleaner 250w is compared to the 75w on the hk. Any suggestions?
     
  2. Matt LB

    Matt LB Auditioning

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    Any help for a newbie??
     
  3. Mark Russ

    Mark Russ Second Unit

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    You can pick up those HK PA 2000s fairly cheap (for around $200). That's a tough little amp for the money.
     
  4. Yogi

    Yogi Screenwriter

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    Any amp with about 125W/ch will do. Dont worry about the 200 W rating on the speakers. just cos they can handle 200W doesnt mean you have to feed em that much power unless you want to test the limits of your hearing and your speakers.
     
  5. DanielMan

    DanielMan Auditioning

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    I can attest to the PA 2000. I don't think another amp can touch it for the price (~$200).

    I'm was in a similar situation. I have a HK AVR45 (4 years old) that puts out 65W X 2 in stereo. After hooking up the PA2000 to power the mains, the clarity and presence improved significantly.

    Anyway, get as much power as you can 'afford'. Just my 2 cents.
     
  6. JohnSer

    JohnSer Stunt Coordinator

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    Mark, Daniel,

    I am looking at external power amps, and interested in your thoughts on the 2000. Are you running them in bridged mode to get 100W a channel? Are either of you driving 4 ohm speakers and primarily interested in music impact. Sorry for all the questions.

    JohnS
     
  7. Mark Russ

    Mark Russ Second Unit

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    John, you do have to run them bridged to get 2 x 100 watts. Or you could drive 4 speakers at 45 watts per channel unbridged. I fired off an email a few months ago to Harman support, and they specifically said that the 2000 will drive 4 ohm speakers with no problem. I honestly feel that it is the best new amp value on the market today.
     
  8. JohnSer

    JohnSer Stunt Coordinator

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    Mark,

    Did HA say that it can handle 4 ohms in bridged mode? Sometimes amps can't handle as low impedence in bridged mode, as they do in normal mode. I couldn't find that info in their online manual or specs.

    JohnS
     
  9. alan halvorson

    alan halvorson Cinematographer

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    You can never have too much power, regardless of the power rating of your speakers (with a few exceptions). For the best price/perfomance ratio, go pro. If there are any consumer amps that can beat a good pro amp in the power per buck race, I am very much unaware of it. Try QSC. Look at this amp QSC PLX1202 from Parts Express. 200 watts a side, 725 bridged, $838 list, considerably less out the door price. Don't let anyone fool you - many pro amps, including this QSC, will sound as good as any consumer amp, at any - yes I do mean that - any price. Very reliable.

    Downside? Fan noise (fans can be replaced with much quieter ones, and QSC won't care - in other words, your warrantee won't be voided) and pro connectors.

    Don't get one of those other wimpy amps until you've at least checked these out.
     
  10. CodyL

    CodyL Extra

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    I too recently bought a PA 2000 for my mains and wrote to HK regarding 4 ohm speakers. Their response was that the amp is "rated for 8 ohm speakers". I then called and talked to someone, and was told that HK does not rate 4 ohm impedence and they wouldn't say whether it would work or not. We have discussed this in another post, but my guess until I saw Mark Russ' post was that HK just wouldn't say it was OK. Now maybe they are saying it is OK, but you will not find it in any written decription from HK. My 2 cents is that 4 ohm is likely fine - bridged or otherwise - but we are on our own if we go that route as far as HK is concerned.

    If anyone knows how to actually test (like from an engineering standpoint) the stability of the amp driving a 4 ohm load, I will find a place to get it tested and report the findings, because this question comes up an awful lot in regards to HK Amps.
     
  11. Mark Russ

    Mark Russ Second Unit

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    OK, I had saved that email, and I went back and dug it up:




    -----Original Message-----
    Sent: Thursday, January 30, 2003 8:46 PM
    To: [email protected]
    Subject: Harmankardon.com: Questions regarding Harman Kardon Products


    Message:
    Model Number: PA 2000
    Hello. Can the HK PA 2000 drive 4 ohm speakers, specifically POLK LSi
    series, and particularly if each speaker is passively biamped with it's
    own PA 2000?
    Thanks in advance.
    Tech Note:
    209.214.160.34,,Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)






    Hello,

    The PA2000 should have no problem driving the Polk speakers.



    Jason Zidle
    Marketing Communications Manager
    Erikson Consumer
    Ph:514-457-2555
    Fx:514-457-0055
     
  12. Yogi

    Yogi Screenwriter

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  13. JohnSer

    JohnSer Stunt Coordinator

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    I ended up getting a used Adcom 545II on ebay. We'll see how I make out. There was just too many "ifs" with bridged mode and 4 ohms.

    JohnS
     
  14. Drew_W

    Drew_W Screenwriter

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    As has been said before, when doubling the power, you only gain 3dB of volume...how they sound is key...more power will yield cleaner, clearer sound.
     
  15. DanielMan

    DanielMan Auditioning

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    JohnSer,

    Looks like I'm a little late. But to answer your questions anyway; yes, I am running the PA 2000 in bridged mode 2 x 100W and no, I am not driving 4 ohm speakers.

    I am currently looking at getting some more efficient speakers than I have now. Klipsch probably. The RF-5 and RF-7 sounds sweet.
     
  16. JohnSer

    JohnSer Stunt Coordinator

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    I maybe way off base, but from what I can tell, when you bridge an amp, one channel takes care of the positive swing, and the other channel the negative swing. Each channel only effectively sees half the impedance load. For the PA2000, it would then have to handle 2 ohm loads in normal mode, which is doutful. It might be able to run 4 ohm bridged at low volume, but have problems at high volumes. Most amp specs that have bridging, that I saw, only mention 8 ohm loads. Anyhow, it probably won't be till late next week when I get to try out the Adcom. [​IMG]

    JohnS
     
  17. Mark Russ

    Mark Russ Second Unit

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    John, just out of curiosity, I hooked a pair of M&K s85 (which are 4 ohm) speakers up to the HK 2000 in bridged mode. It didn't shut down. Matter of fact, it could drive them as loud as I could stand it.
     
  18. JohnSer

    JohnSer Stunt Coordinator

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    Mark,

    Thanks for the input. I am not familiar with those speakers. Did you have them set to large and how long did you run, an hour?, and how hot did it get? I am just curious, since I don't think I'll be looking to get rid of the Adcom anytime soon. The fact the PA2000 can run four ohms bridged, at all, says some good things about this amp.

    Maybe there are different methods of bridging. The one I described is from when I was playing around with some cheap Parapix sub amps. I believe there was another method to place the outputs in parrellel, bur required adding some resistance between, to keep amps stable. When I was looking at the other amp manuals that described bridging, the hook-up required one speaker lead to the positive post of one channel and the other to the negative of the other channel. This led me to believe that the first method I described, is the one highly used. Could be wrong.

    Please don't think I'm bashing the PA2000, I just don't think it was the best solution, for what I wanted it to do, for the money, that I wanted to spend (
     
  19. James Ireland

    James Ireland Auditioning

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    Hi guys, for what it's worth I own a Sony STRVA555ES and a Rotel RB-03 to drive the rear channels, in my experience with this set up the apparent power difference between the Sony, 110 WPC, and the Rotel, 70 WPC, cannot be heard during use, the Rotel never sounds as though it is down on power in comparison to the Sony. I have Kef Q55.2s as fronts, Kef Q35.2s for the side and rears, Kef Q9c center and a Kef PSW 2500 sub. The integration is seamless regardless of which decoding format is being used and the sound is full and satisfying, my point is that modern receivers with their ability to boost and cut the output to the various channels means that you can quite happily use two apparently mismatched power amps like I am doing and use the receiver to equalise the output of the two amps. Just for info I have a Denon DV 2900 for DVD A, V and SACD duties, an Arcam Diva CD92T for CD spinning, Microsonics Digibox for TV, Sony PS 2 for gaming. [​IMG] [​IMG] [​IMG]
     

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