will these receiver underpower my speakers?

Discussion in 'AV Receivers' started by Myo K, Apr 15, 2003.

  1. Myo K

    Myo K Stunt Coordinator

    Joined:
    Mar 27, 2003
    Messages:
    189
    Likes Received:
    0
    im currently using them with mirage omno polar speakers i have bookshelf speakers for fronts and omni center both rated at 125 watts and 150 watts rms respectively.


    im looking for a reciever that has a decent thd, i want clean sound, since i use it a lot for music. i hasitly bought a 5.1 pioneer vsx 411, thats rated at 1% thd and there was a white noise constantly that annoyed me. it ruined everythign the sound of anything that i used it to play

    i had a kenwood 6070 but returned it because of defection, and there were no more units left at BB, that receiver had audio that was good enough for me to listen to music, but those receivers are disconued and sounded as if it was underpowering hte speakers since the level of sound quality jump dramatically after the volume knob passed the 2/5thhs mark

    now im interested in harmon kardon, but i only has about 400-500 dollars to spend and i was look at hk's in that price range for 5.1

    http://shop3.outpost.com/product/3335912

    it has an output power of 45 watts per channel

    http://shop3.outpost.com/product/3335922

    or this one with 55 watts.


    what frightens me is that the kenwood receiver was tested by sv magazine and they rated it at a constant 92 watts per channel through x 6, so if the hk's are 55/45 watts are accurate, then will these receivers kill my speakers?
    people have also told me that the hks are high current (i dont know if the models i listed are high current though)
    and that the kenwood is low current, would that make any difference in powering/underpowering my speakers?

    anyone know the answer?

    thanks a lot [​IMG], sorry for all "?"s im a noobie.
     
  2. Myo K

    Myo K Stunt Coordinator

    Joined:
    Mar 27, 2003
    Messages:
    189
    Likes Received:
    0
    anyone harmon kardon owners?
     
  3. Adam.Gonsman

    Adam.Gonsman Stunt Coordinator

    Joined:
    Jan 9, 2003
    Messages:
    132
    Likes Received:
    0
    Myo,
    I'm not a harmon owner but HK's have a lot of respect from a lot of people on this forumn. I'm sure some HK people will jump in here soon. As for the high current, some say it's meaninful, others say it's marketing. Depends on who you ask.

    I do beleive that HK tends to be more honest about their power ratings than some manufacturers. But to answer your questions about if these HK's have enough wattage, I don't know if there's a cut and dry answer. A lot depends on what size room you have and how loud you like to listen to you music.

    If you tend to keep the volume somewhat low, you'll probably be ok with 45 or 55 watts per channel. But I would be a little worried if it were me.

    Those Mirage speakers have their sensitivity rated at 91db for the bookshelfs and 90db for the center. That's getting down there a little bit in sensitivity. That means that these speakers take more power than some others to drive them to the same volume.

    If it were me, I would be searching for a little more power. Even something around 75 or 85 watts per channel would make me more comfortable. I realize budget is a concern though so you're stuck with a compromise. If music is very important to you, have you considered buying a used or close out model? These may be lacking in some of the newer home theater formats, but would give you a good budget conscious step up in cleaner more powerful amps which would greatly benifit your music.
     
  4. Carl Johnson

    Carl Johnson Cinematographer

    Joined:
    May 6, 1999
    Messages:
    2,259
    Likes Received:
    25
    Real Name:
    Carl III
    My 65 watt HK receiver is easily more powerful than the 110 watt Kenwood receiver that it replaced. I'm not sure how these measurements are taken but I'm sure the HK will be able to safely power your speakers.
     
  5. Myo K

    Myo K Stunt Coordinator

    Joined:
    Mar 27, 2003
    Messages:
    189
    Likes Received:
    0
    Those Mirage speakers have their sensitivity rated at 91db for the bookshelfs and 90db for the center. That's getting down there a little bit in sensitivity.

    really? wow! shows how much i know about speaker hee hee, i thought 91 was pretty good, but then i was comaring them to other speakers that had 85-88db, but then im aware that many of you have multi thousand dollar set ups.

    the previous kenwood receiver i used 6070 got plenty loud.

    my room is about 15'x15', i recall owning a dreaded sony 740 htib which was supposedly rated at 80 watts per channel, but at max volume couldnt even fill a 15'x'15 room with sound.

    --

    i dont have a way of auditioning them so its all or nothing for me.

    everyone tells me that if i get an amp with a power output that does not match the speakers rms, that itll cause the speaker to work harder and the eventually damage it. im sure this is where an audiophile that has insurmountable knowledge of speaker/receivers specs and ratios would come in handy and break down the science into noob poorman terms for me so i may understand this.
     
  6. RobWil

    RobWil Supporting Actor

    Joined:
    Mar 17, 2003
    Messages:
    733
    Likes Received:
    0
    I will concur with Carl...the 65wpc x 2 HK seems to out-power the 100wpc x 2 Kenwood I tested it against. Without knowing anything else an 'electronically challenged' person such as I would be tempted to attribute that to 'high current' vs 'low current' design.
     
  7. Adam.Gonsman

    Adam.Gonsman Stunt Coordinator

    Joined:
    Jan 9, 2003
    Messages:
    132
    Likes Received:
    0
    Myo,
    You're right in the 91db isn't super low. But it's not overly high either.

    You're room is not real large though. This is in your favor.

    As for RMS, powerhandling and all that, it's not so important that you match RMS of your speakers to amp power. What is import is that your amps can provide clean power all the way up to the volume you listen at. Under powering your speakers can damage them. If you want to know more, there are countless discussions on this forum about power handling of speakers.

    Whether 55 watts would be enough power, and without dealing with gain from room size, loss from distance to speakers etc, remember that it takes a doubling of power to acheive a 3 db gain in volume. My main concern here is that because of the exponential power requirements in volume, that in the lower wattages, the differences between a 55 and 65 watt amp are much greater than the differences between a 100 and 110 watt amp. The same wattage difference has greater impact the lower it occurs.

    By the same token, if I were Myo, I would feel much better about buying the 55 watt model than the 45. Based on your room size, I personally would feel comfortable buying the 55 watt and not worrying about speaker damage. I would feel even better yet about a 65 or 75 watt model. Is a 100 or 110 watt needed? No.

    All the above is assuming real wattage ratings. I'm certainly not about to argue with Carl or Rob. I have no doubts that the 65 watt HK out powers the 100 watt Kenwood. My feeling (and I am by far *not* the authority on the subject) on this though is that that has less to do with high current and low current design and more to due with HK is more honest about their specs. A number of brands are known to way over inflate their power ratings.
     
  8. Paul_Fisher

    Paul_Fisher Screenwriter

    Joined:
    Dec 27, 2001
    Messages:
    1,219
    Likes Received:
    1
    Go to www.harmanaudio.com. You can get a refurbished AVR520 for about $550. This is one hell of a receiver. There is nothing wrong with buying refurbished directly from Harmon, they even come with a one year warranty. I bought a AVR 120 refurbed from them and it has worked flawlessly.
     
  9. Adam.Gonsman

    Adam.Gonsman Stunt Coordinator

    Joined:
    Jan 9, 2003
    Messages:
    132
    Likes Received:
    0
    Paul,
    Excellent find. This is definately the way to go in my opinion.
     
  10. Eric_E

    Eric_E Supporting Actor

    Joined:
    Aug 8, 2002
    Messages:
    512
    Likes Received:
    0
    Better yet, J&R has the HK AVR-520 new for $499. [​IMG] I just bought one of these myself, and it came out to $531 after shipping. Should be here on Thursday. [​IMG] I love the fact that I can just add a two-channel amp later if I want to go 7.1, and I love that it doesn't have a fan like the 525!
     
  11. Jonathan M

    Jonathan M Second Unit

    Joined:
    Jul 23, 2002
    Messages:
    267
    Likes Received:
    0
    Note that the difference between 55W and 45W here is minimal - you need to DOUBLE the output wattage to increase the volume by just 3 dB. the increase of 10W hear will make less than 1dB difference.

    Don't worry too much about the rating on the loudspeakers - it is basically meaningless. Reason being that most loudspeaker driver manufacturers rate the power handling capability as the amount of power that the voice coil can withstand before going poof. FAR before you get to this point, the speaker will be exceeding it's Xmech (excursion limits - how far it can move in and out). You'll probably find that many manufacturers use crappy xover components that are rated fairly low so that they blow before the drivers.

    Remember that most people on average only listen to about 1-5Watts or so. 5Watts average will be VERY loud on your speakers (Assuming they ARE 91dB/watt sensitive) in your room. This is due to the peaky nature of music. The average is usually 10-20dB or so below the peak levels (or should be on decent recordings - this is another matter though!) thus you only need between 1/8th and 1/64th of the power requirements on average. The peaks only occur for a very short period of time, and your speakers will likely not fret too much about this because of the short time. You are likely to turn it down anyway if you start to near the limits of the speakers, as it won't sound too good.

    Verdict: Don't panic about the ratings on your speakers. They are all mostly contrived anyway.

    Hope this helps clear things up.
     
  12. RobWil

    RobWil Supporting Actor

    Joined:
    Mar 17, 2003
    Messages:
    733
    Likes Received:
    0
     
  13. Adam.Gonsman

    Adam.Gonsman Stunt Coordinator

    Joined:
    Jan 9, 2003
    Messages:
    132
    Likes Received:
    0
    Jonathon,
    I think you and I are kind of coming at the same point from opposite ends. I won't argue with you that even from 45 to 55 watts doesn't have a tremendous impact. My main point was that it makes more impact from 45 to 55 than from say 100 to 110. After reading my other post, I did come across with too much emphasis on that. Someone feel free to smack me. (ducks)

    But regaurdless, I really thing a used/refurb/closeout like the 530 above would be my option of choice if it were me.
     
  14. MikeMcGrew

    MikeMcGrew Stunt Coordinator

    Joined:
    Apr 17, 2000
    Messages:
    131
    Likes Received:
    0
    Myo, I too can vouch for buying refurbs from Harman. I got a set of JBL speakers (S312's) for less than half of their retail from them and they sound better every day. Their products carry full warranty also so you're good there. All you pay is cost of shipping back if something goes wrong but I talked with a rep who said that they will use "authorized" service centers too. I tell you what though, OneCall has the refurbed H/K 525 for $526.00. This is a nice receiver and it will more than meet your power requirements. They are an "authorized" H/K dealer and they offer very reasonable extended warranties.Check it out here I just checked the item and it is currently out of stock but you can preorder it and they will notify you when it comes in. It has been my experience that it doesn't take that long. Good hunting to you. MM
     
  15. Myo K

    Myo K Stunt Coordinator

    Joined:
    Mar 27, 2003
    Messages:
    189
    Likes Received:
    0
    this is a question for audiophiles techies here.

    how does a speaker spl efficiency level and rms wattage corrolate with a recevers wattage all channels driven?

    if my omni speakers have an efficeincy of 91 decibles per watt per meter, decibles rise in increments of x2,

    then when you calculate

    it would go like this

    watts vs decible level(my fronts)
    ----------------------
    1 watts -91 decibles
    2 watts -94 decibles
    4 watts -97 decibles
    8 watts -100 decibles
    16 watts -103 decibles
    32 watts -106 decibles(dolby digital spl reference level reached)
    64 watts -109 decibles
    --------------
    --------------

    my center has a effiency of 90

    then it would be
    ---------------------
    1 watts -90
    2 watts -93
    4 watts -96
    8 watts -99
    16 watts -102
    32 watts -105(dolby reference level)

    it would take 32 watts of power to attain 104-106 decibles of sound.

    how would this relate to the hk receiver avr 225?
    and why do my speakers have an rms of 125 and 100 watts? how does this relate to receiver compatibilty?
    how doest this relate (if any) to underpowering them?

    so if the hk receiver has 50 watts per channel(i dont know how accurate it is, is the 225, 50 watts per channel x 5? or is it a total of 50 watts through 5 channels being used at once? i dont understand?

    how does clipping come into play? and under what circumstances would cause my speakers to clip? im assuming if theres a spike in sound and the receiver required more then 105 decibles of sound at 32 watts that anyhting above 106 decibles in the spike would kill/harm my speakers tweeter?

    why do speakers post rms watt ratings anyway? what does that mean? is comparing receiver wattst to speaker watts erroneous on my part?

    does 125 rms just mean that the speaker is capable of playing about 112 decibles of sound? then why do people keep telling me that using a low wattage apmplifier/receiver will clip a speaker?

    how loud is 105 decibles anyway? whats the average decible level a person would use for movie watching at a decent loud level?

    how does high current and low current effect clipping? or quality of sound?


    these are the specifications for the harmon receiver
    ---------------------
    Audio

    Stereo Mode Continuous Average Power (FTC) Per Channel: 65 Watts per channel, 20Hz – 20kHz, @
     
  16. Adam.Gonsman

    Adam.Gonsman Stunt Coordinator

    Joined:
    Jan 9, 2003
    Messages:
    132
    Likes Received:
    0
    Myo,
    So your post doesn't drop off the board, I'm gonna try and hit some some of you questions.

    First, 105 decibels is VERY loud. Loud enough to cause hearing damage from continual exposure especially if it's in the upper frequencies.

    However, db gain from amp power isn't the whole story. You also lose volume from distance to speaker. If I remember correctly (someone catch me if I'm wrong) you lose 6 db every time the distance from the sound source doubles. So that would go something like:

    1 meter away: 0 loss (this is the efficiency of your speakers)
    2 meters: -6 db
    4 meters: -12 db (this is total, not cumulative with the lesser distances)
    8 meters: -18db
    ...

    If you're room is ~15 feet across, you're just passed the 4 meters mark. So you're probably losing around 12db till the sound gets to your listening position. (I'm assuming you sit across the room from the speakers, adjust accordingling if you have your couch in the middle of the room or something).

    Things like room shape, ceiling height, exact speaker placement and other factors can cause loss (and sometimes gain) also.

    Don't worry about the RMS rating of the speakers. That's a guide for the maximum continuous power you should allow them to be exposed to. This rating has no effect on the chances of underpowering the speakers.

    As for clipping, clipping occurs in the amp, not the speaker. It just damages the speaker. [​IMG] Clipping occurs when the amp is driven to volumes where it does not have the power to accurately reproduce the full signal that it's amplifying. This causes distorted wave forms to be sent to the speakers which causes erratic movement and momentary pauses in the speaker movement which can cause physical damage to the driver, usually overheating.

    High current, for what merit it has, should help prevent clipping and improve sound quality. How much merit there is to calling an amp high current is a subject of debate, however, as a number of manufacturers claim high current amps but even they don't all agree on just what high current means. There have been a number of debates on the forum about this. Some even consider a high current amp to be any amp rated for power across all frequncies instead of the cheaper amps that are only rated at 1khz. This is one of the most recent.

    Lots of stuff. It's late for me too. 4:20am. I'm going to bed. Hopefully I didn't screw up any explanations too badly from sleep deprivation.[​IMG]
     
  17. Jonathan M

    Jonathan M Second Unit

    Joined:
    Jul 23, 2002
    Messages:
    267
    Likes Received:
    0
    Adam did a great job of answering your questions - superb for a 4:20am effort!

    Just a few pointers:

    1. 105dB is LOUD. As Adam has pointed out, this is at 1 metre, and assumes quite a bit about the speaker. I would suggest that the REAL sensitivity is quite a bit lower overall. Note that it IS likely to be 91dB at some frequency range, but I can almost guarantee that it won't be that down low. (Most mid-woofers are around 87dB efficient, and lose 6dB of efficiency due to Baffle step).

    2. High current amps generally have a more robust power supply and output stage, as a higher current is needed when the impedance of the speaker falls. (Remember V=IR - if R falls as it does on most speakers, I must increase in order to achieve the same voltage swing.) You don't need to worry if the amp you purchase does not state it is high current. All you need is an amp that will drive your speakers to the levels you need. Weight is a fairly good indicator of an amps power capabilitys - but all of the above is generalisation. Seeing as your speakers dip to 4 ohms, you may which to have the safety of a receiver who's amplifier section is rated to handle 4 ohm loads. Most 8ohm rated receivers do have a bit of breathing room, but some don't. If you like to listen loud, then this is something to look out for.

    3. The H/K is specced at 55 watts out of each of the 5 channels simultaneously. 275W total, if you will. H/K's are known for their good amp stages - they will drive your speakers fine.

    4. The "Channel separation" numbers you point out are indicating how well one channel is distinct from the others. Each channel's amplifier is sharing the same power supply, and likely the same PCB, so there is inevitably some cross talk introduced. The 55dB indicates that if you unplugged your left speaker, put the balance far to the left (So that nothing should come out of the right) and crank the volume up, then you would eventually start hearing in the right speaker what should be in the left. Note that the sound level will be 55dB below the level that would be coming out if the balance was set to normal. No need to worry about this - this is a VERY small amount, and there is no way you'd be able to hear this whilst normal stuff is playing.

    I think that answers everything.

    Have a good Easter.
     
  18. Myo K

    Myo K Stunt Coordinator

    Joined:
    Mar 27, 2003
    Messages:
    189
    Likes Received:
    0
    thank you johnathon and adam, your advice and information is greatly appreciated!
     

Share This Page