FIR Cookbook?
in [DSP]
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From: jeff227 on 14 Dec 2006 09:45 >What do you mean by "most popular"? Popular in the music industry. >Where are these products? Recording studios, high-end audio racks, pro audio rigs - people who can tell (and demand) the difference >What are their market shares? Very, very small compared to IPods! (Lamborgini and Ferrari also have small market share). >I never considered myself to be one, but after I got my >MP3 player, maybe I am becoming one. Even my poor 20-year >old stereo rack sounds way better than even a half-decent MP3. Hearing you say that warms my heart! I have a very expensive, all digital, surround system at home that sounds terrible with music program. It is extremely lifeless and sterile compared to my "clunky" old analog stereo system. But you are right, low cost and convenience is what the public wants today. Everything seems to be turning into "plastic", IMHO. (RBJ - I'm afraid to agree but the Line6 does sound great. But I still think it's a *different* sound compared to a real Fender Twin or Vox 30. Maybe I'm just old! Love your "Audio EQ" cookbook, BTW. Thanks for sharing it with the world.)
From: Jerry Avins on 14 Dec 2006 10:52 robert bristow-johnson wrote: ... > i might agree with that, but point out that products such as the Line6 > pod, do a pretty damn good job, if not perfect. there are so many > weird things to account for when emulating vacuum tube distortion. one > that i didn't know until recently was about the mechanical coupling of > the amp bottom (the case with the loudspeakers) to the amp head (the > amplifier with the vacuum tube components). the behavior and sound was > different if the head was mounted on the bottom than if it was set > aside on another pedestal. the vibrations of the loudspeakers were > coupled to some small degree to the internal electrodes, the cathode, > plate, grid (and screen and supressor) of the tube to give it a time > varying behavior that was correlated to the signal. modeling that must > be a male offspring of a copulating female canine. Jeez, man! You didn't know about microphonics? They're not usually a noticeable problem with higher-level signals, but good systems -- living-room audio and aircraft intercoms among them -- used shock-mounted, spring-isolated sockets for the preamp tubes. Do you use a good dynamic mic with a step-up matching transformer? The chances are good that the transformer core is microphonic. Mu-Max, Hi-Mu 80, Mu-Metal, and Permalloy all have enough nickel in them to be very megnetostrictive. Inside the transformer shield you will find resilient foam padding. > also, even if i am alone in this, i see great value to conceptually > coupling the concepts of digital filtering to analog filtering. in > both we have these memoryless components (or operations) that scale > quantities and sum quantities. in both we have components that > necessarily have memory that are used to discriminate one frequency > from another. in analog filters, these are reactive elements, usually > capacitors and their memory is cumulative. in digital filters, these > memory components are simply computer memory and they act like delays. I think that's a powerful conceptual model at your level, and even I appreciate it. I hope you'll agree that trying to use analog models to predict the behavior of digital constructs in order to avoid having to understand something new productive only in rare instances, and then only as a coincidence. > so in both cases, we assemble circuits (that is an appropriate word for > it in both cases) that scale and add quantities, but such would not > discriminate different frequencies. so in both, we add a component > that has a concept of time and the past, so we can discriminate > frequencies. that is where conceptually these analog and digital > filters are comparable. Sure, but the behavior of an inductor, even a perfect one, doesn't say anything useful about the behavior of a digital low-pass filter. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
From: Jerry Avins on 14 Dec 2006 10:58 jeff227 wrote: >> What do you mean by "most popular"? > > Popular in the music industry. > > >> Where are these products? > > Recording studios, high-end audio racks, pro audio rigs - people who can > tell (and demand) the difference > > >> What are their market shares? > > Very, very small compared to IPods! (Lamborgini and Ferrari also have > small market share). > > >> I never considered myself to be one, but after I got my >> MP3 player, maybe I am becoming one. Even my poor 20-year >> old stereo rack sounds way better than even a half-decent MP3. > > Hearing you say that warms my heart! I have a very expensive, all > digital, surround system at home that sounds terrible with music program. > It is extremely lifeless and sterile compared to my "clunky" old analog > stereo system. Try exchanging the speakers on the two systems. No matter how "integrated" a system may be, it's made of components nonetheless. Don't blame the shortcoming of one of the components on the whole system. (I'll bet all your speakers are analog. :-) ) ... Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
From: Jerry Avins on 14 Dec 2006 11:50 Jerry Avins wrote: ... > Mu-Max, Hi-Mu 80, > Mu-Metal, and Permalloy all have enough nickel in them to be very > megnetostrictive. Inside the transformer shield you will find resilient > foam padding. The pair of noise-canceling throat mics used in the Mercury capsule had a five-ohm impedance. There were step-up transformers between them and the transistor preamps. Those transformers used Hi-Mu 80 cores and were enclosed in two shield cans, The inner can was made of Mu-Metal which saturates easily but shields modest fields very well, and the outer can was made of silicon steel, a poorer shield, but capable of carrying a much higher flux. Both the transformer and the inner shield were padded with sheets of soft polyurethane foam, and we passed the vibration tests, but not by a large margin. ... Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
From: Rune Allnor on 14 Dec 2006 12:25
jeff227 skrev: > (Lamborgini and Ferrari also have > small market share). Yes, but they are designed to be automobiles, not "horseless carts". An automobile and a horse cart serve the same purpose: They facilitate some sort of transportation of either people or goods. As such, they share a couple of mutual design factors: They need a position for the driver (probably not the correct English term for the horse cart) and they need some space where to put the goods or passengers they have to transport. And just about there the similarities end. Horses need to be fed and watered, they need to rest and sleep regularly. There is a limit to how heavy load one horse can pull. The automobiles can pull orders of magnitude more load at orders of magnitude higher speed, for orders of magnitude longer distances. The price to pay is that the automobiles require a carefully prepared network of roads, whereas the horse carts only require rudimentary dirt roads. Nevertheless, I would find it ridiculous if somebody suggested that an automobile should be designed to meet the limitations of the horse carriage, just because they happen to serve the same functional purpose. There is no need to design DSP systems from analog specs and limitations, just because the task assigned to the DSP system can be solved by an analog system. Rune |