dynaco_dan Posted August 12, 2005 Report Share Posted August 12, 2005 Hi thereI was just going over some of my old notes and thought some of it might be of value to someone today.Crown, ( Amcron, the USA amp builder ) has published much helpful information in the past.They seem to feel 10 guage stranded wire is best for normal use.The difference in an amp with normal Damping Factor and one with more than enough is quite audible.The case between an AR amp and Crown DC-300-A amp was very dramatic in the case of in my home with the same music.The Crown not only had bass you could hear, also in another part of the house you could still feel it in your stomach. Not so with the AR. I owned the AR amp, I had used it for several years before this comparison.They feel that slow blow fuses should be used for the woofers as their characteristics are close to the way the fuse functions. But in the mid and tweeters they feel you should fuse them separately with fast blow fuses.I would suggest open block fuse holders rather than in-line fuseholders. This would allow more heat to escape.In the chassis type may be more concealed but will contain the heat.Heathkit AS-103/AR-3A kits were an AR co-ordinated effort and Heath included a chassis mount fuseholder and an o-ring to seal the holder from air leakage, how thorough, heh?Somewhere long ago I read that an AR-3 only needed an amp with a Damping Factor of 7 if I rememeber correctly.Also if you used the 5 @ fast blow fuses that came with DC-300A they would not blow with full output into 4 ohms.I have seen the old published data re. IHF ratings, the DC-300A was rated at 800 watts total output at 4 ohms.Looking forward to your input or feedback.Vern Link to comment Share on other sites More sharing options...
soundminded Posted August 12, 2005 Report Share Posted August 12, 2005 "The Crown not only had bass you could hear, also in another part of the house you could still feel it in your stomach. Not so with the AR. I owned the AR amp, I had used it for several years before this comparison"I cannot agree. I used an AR amplifier to drive original Bose 901 speakers in a ground floor apartment in a suburb of Baltimore MD many years ago. The woman living on the third floor complained that I rattled her dishes. Bass was deep and powerful as expected with the AR amplifier. It's power bandwidth on the low end extended to at least 20 hz where it had negligable distortion. It was rated for 50 wpc into 8 ohms and 60 into 4. It typically could produce at least 90. My oscilloscope showed no signs of clipping either. Damping factor has to do with the amplifier's ability to dissipate energy fed back at it by the woofer's inertial momentum acting as a generator. It is directly related to the amplifier's output impedence and is defined as the load impedence divided by the source impedence (which also takes the speaker wire impedence into consideration.) It is exactly the same principle as dynamic braking of rotary motors. Loudspeakers which are poorly mechanically damped can exhibit spurious ringing at low frequencies with amplifiers having a low damping factor. This gives them a boomy muddy bass. Solid state amplifiers rarely have this problem, it is more closely associated with vacuum tube amplifiers which have an inherently high source impedence due to the plate characteristics of tubes and require an impedence matching transformer to deliver appreciable power to the load."Also if you used the 5 @ fast blow fuses that came with DC-300A they would not blow with full output into 4 ohms"5 amps at 4 ohms is 200 watts. There are hardly any conceivable instances where a loudspaker in a home environment would deliberately be pushed that hard. BTW, as I recall, wasn't the crown DC 300A rated at 180 watts per channel? A smaller fuse should be use to protect the midrange and tweeters which are far more vulnerable to damage from overdriving. Link to comment Share on other sites More sharing options...
rrcrain Posted August 12, 2005 Report Share Posted August 12, 2005 Maybe my math and memory are rustier than I thinkt hey are, but isn't power= I^2R? If that's correct (and I may not be) wouldn't 5 amp at 4 ohms be 100 watt? (5*5)*4=100For what its worth, my amp will on very rare occasions hit full power on extreme transients into my AR90s, and thats 500W per channel. Link to comment Share on other sites More sharing options...
soundminded Posted August 12, 2005 Report Share Posted August 12, 2005 You are of course 100% correct. 100 watts is still a lot of power to put through an AR woofer but it should blow a 5 amp fast blow fuse. Link to comment Share on other sites More sharing options...
dynaco_dan Posted August 12, 2005 Author Report Share Posted August 12, 2005 Hi thereThe Crown not only had bass you could hear, also in another>part of the house you could still feel it in your stomach. Not>so with the AR. I owned the AR amp, I had used it for several>years before this comparison">>I cannot agree. I used an AR amplifier to drive original Bose>901 speakers in a ground floor apartment in a suburb of>Baltimore MD many years ago. The woman living on the third>floor complained that I rattled her dishes. Bass was deep and>powerful as expected with the AR amplifier. It's power>bandwidth on the low end extended to at least 20 hz where it>had negligable distortion. It was rated for 50 wpc into 8>ohms and 60 into 4. It typically could produce at least 90. >My oscilloscope showed no signs of clipping either.I still have my AR amp and so I make this comment with decades of usuage and having read numerous articles as well. The amp has a tilt downward in level from the bass to the treble, similar to their general bass heavier, treble shy speakers. Subjective comment.When I bought my amp new, I don't think I ever used the tone controls, I was lead to believe in leaving tone controls out of the circuit, if you can.I was listening at normal levels when I went to the opposite end of my home in anther room for something and I commented to my ex about, "do you feel that bass"? There was bass in my living room with the AR amp, but, not to the depth or control that the Crown had. When I turned on the Crown Amp it took about 30 seconds to know that the Crown was superior in the deepest bass and everwhere else. I think I said wow more than once. I would say that the difference between these amps at normal levels was similar to a comparison of the AR-5 and AR-3A's. You have to remember that the AR amp was about $400.cdn at the time and the Crown DC-300A and IC-150 combo was about $1200.cdn.. At another time when I was able to borrow AR-LST's, I was left with a feeling, and commented that, I felt they were worth twice as much as AR-3A's, and I owned AR-3A's at that time.. >>Damping factor has to do with the amplifier's ability to>dissipate energy fed back at it by the woofer's inertial>momentum acting as a generator. It is directly related to the>amplifier's output impedence and is defined as the load>impedence divided by the source impedence (which also takes>the speaker wire impedence into consideration.) It is exactly>the same principle as dynamic braking of rotary motors. >Loudspeakers which are poorly mechanically damped can exhibit>spurious ringing at low frequencies with amplifiers having a>low damping factor. This gives them a boomy muddy bass. >Solid state amplifiers rarely have this problem, it is more>closely associated with vacuum tube amplifiers which have an>inherently high source impedence due to the plate>characteristics of tubes and require an impedence matching>transformer to deliver appreciable power to the load.>>"Also if you used the 5 @ fast blow fuses that came with>DC-300A they would not blow with full output into 4 ohms">>5 amps at 4 ohms is 200 watts. There are hardly any>conceivable instances where a loudspaker in a home environment>would deliberately be pushed that hard. BTW, as I recall,>wasn't the crown DC 300A rated at 180 watts per channel? A>smaller fuse should be use to protect the midrange and>tweeters which are far more vulnerable to damage from>overdriving. I quoted from Crown re the 5 @ fuse @ 4 ohm load."quoted without permission""The most common of all protection schemes is a fuse in series with the load. The fuse may be single, fusing the overall system. Or, in the case of a multi-way speaker sytem, it may be multiple with one fuse on each speaker. Fuses help prevent damage due to prolonged overload, but provide essentially no protection against damage that may be done by large transients and such. To minimmize this problem, high-speed instrument fuses such as Littlefuse 361000 series are most appropriate for such applications." The reason they wrote this was to show that it offered no protection for home speakers and it went on to recommend or suggest a slow blow fuse for the woofer.I am trying to remember all the details of the '60's about IHF and FTC I believe. Anyhow, the old watts IHF rating was not what AR subscribed to as I remember. AR used watts RMS per channel both channel running 20 - 20,000 at a specified distortion and impedance. There was a period when Crown didn't publish there spec's as they were forced to or just waited for the new standards to come out. I remember, and I don't know what organization was asking everyone to submit their suggestion as to what the new standard should be. I did receive a reply from a US Congresssman, if I remember correctly, thanking me for my input and later I was notified of the results. Lost this info, I don't remember the outcome either. Even as a Canadian my input was welcomed at that time. I am going to quote from my DC-300 manual as my DC-300A manual was not printed in these spec's.4 ohm load DC - 20,000 typical response 400w IHF per channel 340w cont one channel 300w cont both channels operating 250w shown as a reference on graphJust as a side note.Long ago I listened to Quads 57 with a AR-3 with a custom crossover, playing Also Sprach Zarathustra's opening, made me feel ill, in a very large living room, with a Dynaco Stereo 70 amp. I believe this was a 32hz tone on that particular record.I'm tired now, so if there is more I'll be back.Vern Link to comment Share on other sites More sharing options...
dynaco_dan Posted August 12, 2005 Author Report Share Posted August 12, 2005 >"The Crown not only had bass you could hear, also in another>part of the house you could still feel it in your stomach. Not>so with the AR. I owned the AR amp, I had used it for several>years before this comparison">>I cannot agree. I used an AR amplifier to drive original Bose>901 speakers in a ground floor apartment in a suburb of>Baltimore MD many years ago. The woman living on the third>floor complained that I rattled her dishes. Bass was deep and>powerful as expected with the AR amplifier. It's power>bandwidth on the low end extended to at least 20 hz where it>had negligable distortion. >It was rated for 50 wpc into 8 ohms and 60 into 4. It typically could produce at least 90. My oscilloscope showed no signs of clipping either. The AR amp does, as you say it does, you are correct, but the AR 12" woofer's impedance goes up to about 30 - 40 ohms below 100hz, you can see that AR's 90 watts wasn't available for it, but more like maybe 10 - 20 watts or even less. Sorry, but my notes on this are still packed up, but, it's between 30 and 40 ohms, no doubt. And we're talking sine wave signal as well.The Crown, would also not have it's full rated output, still substantially more.The damping Factor for their DC-300A is greater than 200 zero - 1,000hz @ 8 ohms and typical @ 100 hz almost 1100 @ 8 ohm.Sorry but the 4 and 16 ohm Damping Factors are not shown or listed.I don't have my AR amp Damping Factor handy so I can't comment, except, that I believe it was fairly low by comparison.The ongoing exchange of knowledge is neverending.Have a good one.Vern>>Damping factor has to do with the amplifier's ability to>dissipate energy fed back at it by the woofer's inertial>momentum acting as a generator. It is directly related to the>amplifier's output impedence and is defined as the load>impedence divided by the source impedence (which also takes>the speaker wire impedence into consideration.) It is exactly>the same principle as dynamic braking of rotary motors. >Loudspeakers which are poorly mechanically damped can exhibit>spurious ringing at low frequencies with amplifiers having a>low damping factor. This gives them a boomy muddy bass. >Solid state amplifiers rarely have this problem, it is more>closely associated with vacuum tube amplifiers which have an>inherently high source impedence due to the plate>characteristics of tubes and require an impedence matching>transformer to deliver appreciable power to the load.>>"Also if you used the 5 @ fast blow fuses that came with>DC-300A they would not blow with full output into 4 ohms">>5 amps at 4 ohms is 200 watts. There are hardly any>conceivable instances where a loudspaker in a home environment>would deliberately be pushed that hard. BTW, as I recall,>wasn't the crown DC 300A rated at 180 watts per channel? A>smaller fuse should be use to protect the midrange and>tweeters which are far more vulnerable to damage from>overdriving. Link to comment Share on other sites More sharing options...
dynaco_dan Posted August 17, 2005 Author Report Share Posted August 17, 2005 Hi thereJust to add to this discussion I went to the Crown Audio web site.They have several very interesting articles and " Damping " and " How much power do we need" are just two that you may find interesting.Knowledge is neverending. Link to comment Share on other sites More sharing options...
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