How to tell before driving an amp into clipping?

Discussion in 'Archived Threads 2001-2004' started by Chris Brown, Aug 23, 2002.

  1. Chris Brown

    Chris Brown Stunt Coordinator

    Joined:
    Aug 14, 2002
    Messages:
    178
    Likes Received:
    0
    Real Name:
    -
    Is there any way to know "It's time to turn it down" before your amp goes into clipping?

    Sometimes I can't even enjoy a movie loud for fear that it might switch to a scene with a huge explosion and make my amp clip.

    I've heard that it takes less than one second to destroy parts of a speaker when you drive your amp into clipping. That freaks me out. Does it distort first? Is it possible that your listening to the movie loud, and then all of a sudden there is some loud scene and CLIP there goes the speakers?

    I don't have any experience with this, and I can't be the only one that wants to protect the large ammounts of $ invested in speakers. Any advice?
     
  2. David Berry

    David Berry Stunt Coordinator

    Joined:
    May 9, 2002
    Messages:
    150
    Likes Received:
    0
    Chris,
    Specifically, what amp and speakers do you have? I have a Bryston 3B-ST amp (120W/channel) paired with Paradigm Studio 60 speakers (8 ohms nominal) and I have never got the amp to "clip". I have an Ace of Bass CD that has a lot of bass (go figure[​IMG] ) and have turned up the volume to the point where it is hurting my ears at about 3 meters away (I only subject myself to this for a minute or two with the family out of the house).
     
  3. Chris Brown

    Chris Brown Stunt Coordinator

    Joined:
    Aug 14, 2002
    Messages:
    178
    Likes Received:
    0
    Real Name:
    -
    I use a Pioneer D811S, but use the amp portion of a late 70's vintage receiver to power my speakers (From the pre-out on my pioneer).
    My speakers themselves are vintage JBL L150's.
    The reason I use the amp from the old receiver is simply because it has more power than the Pioneer, although I don't know the exact watt rating. (Can't find any specs for it, except that it has a power consumption of 550watts, which is not bad for a stereo receiver)
     
  4. Yogi

    Yogi Screenwriter

    Joined:
    Jul 25, 2002
    Messages:
    1,741
    Likes Received:
    0
    Hmmm..interesting question. I don't know of any way to tell if an amp is going to clip or not. Once it clips you can tell but knowing when it will clip might require some art(I have no idea). If you have clipping indicators on the amps they are a good way to tell if the amp is going into hard clipping but other than that I dont know. Any body else know how to tell? I would be interested to know.
     
  5. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
    I'll listen to the peaks of the soundtrack or music. When it starts sounding distorted or compressed I back down the volume.

    pretty safe, but the volume changes with source material. some are recorded stronger than others.
     
  6. Yogi

    Yogi Screenwriter

    Joined:
    Jul 25, 2002
    Messages:
    1,741
    Likes Received:
    0
     
  7. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
    Yogi,

    I'm not sure of the details, but when I hear it start to compress and loose dynamics I just turn it down. Could be speakers or amp, but you can tell the difference between amp distortion and speaker distortion.

    I've always assumed a compressed sound that looses its punch and tightness was clipping?
     
  8. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    distortion rises rapidly as one pushes the limits of the amp/receiver past its rated output. typically it'll affect the upper frequencies and your tweeter will eventually wave the white flag if it goes on long enough. as far as the power rating of your receiver why don't you give the make/model and maybe someone's got a handle on the actual numbers.
     
  9. Chris Brown

    Chris Brown Stunt Coordinator

    Joined:
    Aug 14, 2002
    Messages:
    178
    Likes Received:
    0
    Real Name:
    -
    The receiver is a Fisher RS-1050. I don't even know for sure if it is a late 70's/early 80's receiver except that it looks of the time period. As i've said before the fact that it consumes 550watts is the extent of my knowledge concerning the exact specifications of the receiver.

    It works quite nicely. On the back it has 2 sets of RCA jacks that normally have a simply metal bar connecting them. they are labeled "Control Out" and "Power In". Connecting RCA cables from the front pre-outs on my pioneer to the "Power In" on the fisher allows me to tap directly into the internal AMP on the old receiver.
     
  10. john_focal

    john_focal Agent

    Joined:
    Aug 22, 2002
    Messages:
    37
    Likes Received:
    0
     
  11. John Royster

    John Royster Screenwriter

    Joined:
    Oct 14, 2001
    Messages:
    1,088
    Likes Received:
    0
    Best way to describe it...
    amp distortion sounds electronicly induced, smeared. Turn up a stock car stereo and you'll know what I mean.
    speaker distotion is a little more subtle and sounds "phsical" like bass getting loose, snares don't have that taught sound, symbols tend to blend togheter.
    All of this is from my experience so I could be way off base here.[​IMG]
     
  12. AllanN

    AllanN Supporting Actor

    Joined:
    Mar 15, 2002
    Messages:
    950
    Likes Received:
    0
    What does clipping sound like? The only time I heard any distrotion of my JBL N38's paired with a D811S was with my blueman group DVD. It started hitting some real hard base, there was not that much distortion but I think think my poor little 8" drivers where about to jump out of the cabinet. This was played at ref.
     
  13. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    well the rs-1022 was a 22 watt/channel receiver so i'd imagine yours is 50wpc. based upon what you've said so far it seems that you're just running out of gas with the receiver. according to your link, the speakers have an 88 sensitivity which is pretty good but they can take up to 300 watts. i dare say even with your receiver you're still capable of driving them fairly loudly. however with passages that have a substantial kick, your receiver just won't be able to deliver the power. pretty cool though...are your speakers in as good shape as that link?
     
  14. Chris Brown

    Chris Brown Stunt Coordinator

    Joined:
    Aug 14, 2002
    Messages:
    178
    Likes Received:
    0
    Real Name:
    -
    Well, i've never actually had it clip or distort before, so I don't think that i'm running out of power, I just don't want it to happen when i'm least expecting it. I'm trying to "do my homework" so to speak.
    The receiver may very well be 50wpc, I just wish there was a sure way to tell. Other old receivers i've used before have been a Pioneer SX-780 which I believe was 45wpc and an old JCpenny's brand receiver which i believe was 35wpc. This old Fisher receiver seemed a lot more powerful than those two, and even louder and with more oompf than my Denon PMA-560 Integrated AMP, which was 70wpc..... So thats why I thought it might be higher, but now i'm just confused.
    I'm not sure how i'm going to get down to the bottom of this little mystery of mine. I know that with the external receiver amp, -20 volume is louder than -10 was just using the internal pioneer amps during the TPM pod race scene.
    These JBL's are awesome and are in PERFECT condition. My uncle bought them in Germany when he was in the military and brought them back when he came back, They have pretty much been sitting in the corner of his house not being used for many years. The foam was still intact even, but the first time I played them the foam came apart so I had them refoamed. I keep the walnut cabnets nice and oiled and they are great. Even if they maybe aren't as good as some of the higher end new stuff, there is just something cool about impressing your friends with 20+ year old speakers [​IMG]
    I watched "We were soldiers" last night and it didn't seem to have any problems with the loud explosions and gunfire, but I'd still like to know what my system is capable of. Thanks for your help everyone.
     
  15. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    well like i said, based upon Fisher's designations for model #'s I'm pretty sure yours is 50wpc...now if we take a look at your speaker sensitivity 88, which in a room environment is about 91 due to sound reinforcement that means if you're sitting 1 meter away the sound pressure will be 91 dB with one watt of power. 8 watts of power will give you an SPL of about 100 dB which will affect your hearing permanently if you listen to it continuously. doubling your distance to say 2 meters will require 32 watts of power to give you the same perceived loudness. More likely than not, you're pretty much ok. Not knowing much about the Fisher you've got and how it actually measured on the bench, i'd guess that its fully capable of dealing with momentary bursts of sound such as from a rifly or cannon shot.
    i just saw that movie today....disturbing realism I must say.
     

Share This Page