--------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCJ00004 Date: 08/10/96 From: T OWEN Time: 06:27pm \/To: BONNIE GOODWIN (Read 2 times) Subj: Re: Impedances -=> Quoting Bonnie Goodwin to Drew Hohmann <=- DH> It's widely known that running amplifiers below certain load DH> levels (usually 4 ohms), the amplifier has less and less control DH> over the speaker movement, causing distortion. This is mostly DH> seen in groups of subs wired in parallel, down to an ohm or so. BG> I don't believe that is actually true, but often it results in BG> distortion, since the amp is working much harder at a lower impedance, BG> often exceeding the capabilities of the amp, which was why you made BG> the observation above. Actually, damping factor (control over the BG> speaker in essense) increases the lower the impedance. This is a BG> good thing for subs, as the amp is able to dump more power to the BG> speakers and have better control. What? Damping factor *increases* with lower impedance? How is that? I have never seen anyone claim that; in fact, quite the opposite. I am aware that lower impedances will allow better power transfer, but in my experience, the "damping factor" falls off, rather than increasing with lower impedances. Most amp manufacturers state in the spec sheets that "damping factor" is best at 8 Ohms, and gets progressively worse with lower impedances. Most interesting! Take care, and nice to see the "car audio" ousted! ... "Don't be so sentimental, mother. Things explode every day." --- Blue Wave/DOS v2.30 * Origin: Computer Castle / 20 Lines / Newton, NH / 603-382-0338 (1:324/127) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCJ00005 Date: 08/10/96 From: T OWEN Time: 06:39pm \/To: DON GUY (Read 2 times) Subj: Re: Lousy live sound -=> Quoting Don Guy to Bonnie Goodwin <=- BG> (Fletcher-Munson curve)not at loud volumes. DG> Eek. I'm a programmer, not an audiophile! :) Don't worry, most audiophiles don't have a clue what the Fletcher- Munson curve is. :) BG> The mix position was probably in a lousy location, and the guy BG> didn't have a clue as to what it really sounded like in the BG> "listening" position of the audience (that's what counts). DG> Hard to say. The mixer was positioned more or less in the center of DG> the room, and I was at a table directly behind it. The center is not always the best place to mix from; often you get comb filter effects in the center; I prefer to mix from a bit off-center in most rooms, unless I am running a deck at the mix position, and need an accurate stereo image going to tape. Take care. ... Liberace was great on the piano, but sucked on the organ. --- Blue Wave/DOS v2.30 * Origin: Computer Castle / 20 Lines / Newton, NH / 603-382-0338 (1:324/127) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCJ00006 Date: 08/10/96 From: T OWEN Time: 06:44pm \/To: DON GUY (Read 2 times) Subj: Re: Lousy live sound -=> Quoting Bonnie Goodwin to Don Guy <=- >BG> The EQ curves are all "disco" curve smiley faces.. lots of sizzle >BG> from the top, and lots of boom, and nothing else. So many folks just don't understand EQ, and the resulting phase incoherence! I don't usually switch in my mains EQ, unless I absoloutely must, especially since I don't have top-notch EQ to start with. I sure would like to have a couple CP-10s for house EQ, but can't foot the bill for those yet. Now I use the new Ashleys, which are good for the money, but just can't compare to the Meyer. Take care. ... If you have to ask what Jazz is, you'll never know. --- Blue Wave/DOS v2.30 * Origin: Computer Castle / 20 Lines / Newton, NH / 603-382-0338 (1:324/127) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCJ00007 Date: 08/10/96 From: T OWEN Time: 06:53pm \/To: KEN HOTTE (Read 2 times) Subj: Re: Lousy live sound -=> Quoting Ken Hotte to Bonnie Goodwin <=- KH> The DJ booth is floored out of poured concrete to the same height as KH> the stage, and the Turntable Stand is a poured curved block of high KH> grade concrete. It sits upon cement blocks that are mortared to the DJ KH> booth floor. The blocks are filled with a lead/sand mixture. The KH> equipment racks are flown from the bottom of the curved Turntable KH> stand (which is about 6" thick) on steel rods that are embedded in it. KH> Each shelf is damped at it's flying point to mechanically damp and KH> separate it from the vibration of the floor and room. KH> In case of nuclear attack, hide in the DJ booth. No kidding! That's a serious structural setup! KH> Next is Bag End. KH> Much better performance. Sealed box Subs, with Custom EV drivers. Same KH> in the mid/high boxes. The mid/high are ported. 115 DB, average slow. KH> Flat to about 15 hz. SERIOUS subsonics. Punchy and as controlled as KH> you could ask for. My personal favorite. Oh yeah! Those Bag end operate below resonance, and they are some of the nicest subs around; how they did that is a bit complex, but I have heard them, and they *are* very impressive! I haerd a system with the integrator that flattens response to 8 cycles, and was instantly in love. What a great system (if a bit complex to set up, with all those dip switches)! I am considering gatting some of that stuff for home listening/massage. Take care. ... I'll have what the Gentleman on the floor had. --- Blue Wave/DOS v2.30 * Origin: Computer Castle / 20 Lines / Newton, NH / 603-382-0338 (1:324/127) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCJ00008 Date: 08/14/96 From: GORDON GILBERT Time: 04:04pm \/To: DREW HOHMANN (Read 2 times) Subj: DOLBY -=> Quoting Drew Hohmann to Cameron Hall <=- DH> good point here. I thought that the CD player spun the disc at a DH> constant rate, like a record player. Though now you have me DH> confused. A record player rotates at a constant rate, yet even DH> though the inside edges and the outside edges travel at different DH> speeds, their is no difference in pitch between the outside and DH> inside edges. (Meaning if you had a 33 record playing at 45rpm, DH> it'd be higher pitched, yet even though the edges are traveling DH> at different speeds, it's the same pitch throughout the record). DH> Seeing how it's summer, my brain isn't working the way it should, DH> so can you please explain this? There are two types of discs and ways of reading discs, be they LP, Laserdisc, or CD. You have CLV (Constant Linear Velocity) and CAV (Constant Angular Velocity). The LP is CAV. The platter rotates at a constant angular velocity. The information is recorded this way so playback reproduces it the same way it was recorded. I'm not sure of the efficiency of this method for LPs since groov width can vary depending on the compression for bass and what not, I believe (someone correct me if I'm wrong...I'm no expert on LPs). Maybe someone knows about efficiency here. Although even if CLV was more efficient, I think you'd have some trouble varying the speed of the turntable while mainting accuracy since the information is directly on the disc in wave form. The CD is CLV. The disc is spun at a variable rate to fit the maximum amount of data possible onto the disc (since obviously the outer diameter is larger than the inner and so more data can be fit around it and since the outer edge of a disc is moving linearly faster than the inner, it must be slowed down to maintain the same linear data rate). And since it's digital and can be buffered, it's not important to have *exactly precise* reading speeds. If CDs were CAV, either the CD would have to buffer ahead all the information it's reading (because it would be reading data faster and faster as it approaches the outer edge), which would require vast amounts of RAM or it would have to space the pits further and further apart, which would waste space. Laserdiscs come in both types. CAV laserdiscs store 1 image per revolution. To get a freeze frame picture, the laserdisc merely keeps the laser on the same part of the disc and keeps it moving at the constant playback rate. Thus, it simply displays the same picture over and over again, giving the illusion of a freeze frame. It's also easy to do slow motion/fast motion effects in forward or reverse because regardless, there is always 1 video frame per revolution. The laser merely tracks back and forth at varying rates to accomade varying slow/fast speeds. It's smooth as silk. The bad part is that the playing time of CAV discs is limited to 30 minutes a side. CLV laserdiscs have the advantage of storing 60 minutes a side (double the time of CAV) by varying the angular speed to maintain a constant linear velocity which in normal playback works just fine and makes far more efficient use of the outer parts of the disc. However, if you try to use that freeze frame effect described above, it would have part of another frame (possibly more than one frame the further out you go) in the picture as well since data is crammed onto the disc as much as possible. Therefore, those advantages of CAV are lost. More expensive players use digital memory to store a freeze frame and perform computer animation style buffered slow/fast motion (usually lower quality than a CAV disc, however). * AmyBW v2.14 * ... If Q were castrated would he become ... O? --- FLAME v1.1 * Origin: CanCom TBBS - Canton, OH (1:157/629) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCK00000 Date: 08/15/96 From: JOHN HICKMAN Time: 7:54 am \/To: HERRY BUDIUTAMA (Read 2 times) Subj: Dolby HB> Does hiss consist of high-frequency noises? By this > definition if the hiss contains any low-frequency sounds, > it won't be eliminated. "Hiss" generally refers to high-frequency background noise. "Hum" is generally used to describe low-freq noise. With turntables it's called "rumble", but that's due to mechanical vibrations. HPF's (High-Pass Filters) are used to remove unwanted hum, in amp circuits, for example. > And what does headroom do? Headroom is defined as the region between the maximum recording level specified by the manufacturer of the equipment, and the amplitude at which tape overload occurs. It's specified in dB. As you can surmise, the greater the dB headroom, the better. > Why is saturating the tape bad? Saturation, in this case, is the point beyond a magnetic material's ability to handle any additional flux. Distortion occurs. Very poor fidelity results. > What is the purpose of the bias in the tape? The bias applied to a tape head is an ultrasonic signal fed along with the music information to keep the oxide magnetization within the linear portion of its hysteresis curve. The various tape types are manufactured for optimum linear recording characteristics which correspond to the recorder's bias setup. Which is why you need to use Hi-Bias tape if you're recording in Hi-Bias mode, Metal tape if you're recording in Metal mode, etc. Most tape decks are are designed to automatically switch to the proper bias levels to match a given tape. --- JABBER v1.2 Would advice from Q be considered a Q-tip? --- AdeptXBBS v1.07f (Registered) * Origin: ATAS Computing, Baytown, Tx. (1:106/8003) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCK00001 Date: 08/15/96 From: WHTFALCON Time: 11:41am \/To: DAMAGE (Read 2 times) Subj: My password is showing in the voting Hi, I just went to vote and i noticed my password was showing? i hope no one else see it beside of me. later --- GEcho 1.00 * Origin: xfader.bbs 613-247-2785 (1:163/335.34) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCK00002 Date: 08/14/96 From: MIKE DALE Time: 11:59pm \/To: KURT J. TISCHER (Read 2 times) Subj: Re: ohms -> KJ> resistance to current flow the speaker has. The best way to see KT> if your -> KJ> speakers will work on your 6 ohm minimum outputs, is to test the -> KJ> speakers on an ohm meter or multi-meter for their true KT> resistance. Even -> Hi Kurt, How would I go about testing the speaker? I've got an ohm -> meter. Does it include takeing out the speaker? KT> Well, not necessarily. All you really need to do is put the positive KT> pin of the ohm-meter on the positive lead or connector of the KT> speaker and same for the negative and see what the reading is. KT> Actually, if you have the pins reversed I dont' think it will matter KT> much, the resistance is still the same. If you are talking about some KT> kind of 3-way enclosure, then definitely measure the resistance of the KT> whole circuit, not just the woofer, because the passive crossover will KT> add some resistance, too. It Shouldn't really matter what it says through the multimeter... The position of the voice coil will change the resistance of the circuit. Therefore the best way to tell is that if the amplifier or whatever it was that wants no lower than 6 ohms, then what you should do is go by the RATING on the speaker. If it is rated at 8 ohms.. then use it by all means... if four ohms, then don't. If you can't find it, then look on the spec sheet or call the manufacturer. Oh, one other thing... If it is 8 ohms... hook it up by itself or in series with another speaker.... Hooking two 8 ohms in parallel would cause a drop to 4 ohms and therefore would wrek whatever if was not supposed to be lower than 6... The ratings is what you have to go by. The multimeter test doesn't prove a heck of a lot. -McDale -!- IceEdit v1.60 [Eval] --- Ezycom V1.20 * Origin: The Vanishing Tower Kamloops B.C. Canada (1:353/730) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCK00003 Date: 08/15/96 From: MIKE DALE Time: 12:06am \/To: MATT ION (Read 2 times) Subj: Re: ohms JH>> If my reciever had 6 ohm(minimum) speaker outputs, and I was running JH>> 4 oh speakers. Would that damage the speakers or the reciever? Can JH>> someone explain to me the difference in a 4 ohm to a an 8 ohm? KJT> I am not sure if a difference of 2 ohms would damage the speakers KJT> or the receiver. MI> If he doesn't over-drive the speakers, it shouldn't hurt. Actually, that is untrue.... NEVER drop below the rated impedence of an amplifier... It may go good for a bit... But if it says like (2 ohms stable) then that is the limmit you should be listening too. If it is 6... Don't go below it. You'll never be able to turn it up loud like that because too much current would be flowing through the amplifier because of the low resistance. It is not a good idea to go lower than 6 ohms.... I would not do it. It shouldn't hurt the speakers at all unless when the amp blew up becasue of too much current it make bad sounds which damaged the drivers. Anyways... I'll tell you now... It is not a good idea to use 4 ohm speakers with that amp. You'll be sure to wreck your amp if not right away. Soon. -McDale -!- IceEdit v1.60 [Eval] --- Ezycom V1.20 * Origin: The Vanishing Tower Kamloops B.C. Canada (1:353/730) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: DCK00004 Date: 08/14/96 From: MATT ION Time: 02:28pm \/To: DREW HOHMANN (Read 2 times) Subj: Re: Dolby And so it came to pass, on 08-11-96 16:46, that Drew Hohmann spake unto Cameron Hall: DH> So the CD player rotates the CD at different speeds as it reads the DH> disc from inside to outside? You'd think that it would be DH> difficult to set each CD player to such exact specs, Not really -- just monitor the data stream coming off the disc and maintain the speed to keep it constant. DH> John has a good point here. I thought that the CD player spun the DH> disc at a constant rate, like a record player. Though now you have DH> me confused. A record player rotates at a constant rate, yet even DH> though the inside edges and the outside edges travel at different DH> speeds, their is no difference in pitch between the outside and DH> inside edges. (Meaning if you had a 33 record playing at 45rpm, DH> it'd be higher pitched, yet even though the edges are traveling at DH> different speeds, it's the same pitch throughout the record). That's because it's recorded the same way. If you play with the pitch control on a tape deck while recording, then adjust the pitch control exactly the same way on playback, there's be no audible change in playback.