Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!decvax!ittatc!dcdwest!sdcsvax!sdcrdcf!hplabs!qantel!dual!lll-lcc!lll-crg!gymble!umcp-cs!seismo!rochester!ur-tut!junk From: junk@ur-tut.UUCP Newsgroups: net.audio Subject: Re: Help on designing speakers Message-ID: <76@ur-tut.UUCP> Date: Wed, 19-Mar-86 13:45:24 EST Article-I.D.: ur-tut.76 Posted: Wed Mar 19 13:45:24 1986 Date-Received: Sat, 22-Mar-86 08:12:24 EST References: <3182@sdcc3.UUCP> <33@ur-tut.UUCP> <1055@psivax.UUCP> Reply-To: junk@ur-tut.UUCP (Jan Vandenbrande) Distribution: na Organization: Univ. of Rochester Computing Center Lines: 94 Keywords: Speaker design ==> Replie ... This is in replie to the replie to my previous message: In article <1055@psivax.UUCP> tommie@psivax.UUCP (Tom Levin) writes: >... >cabinets and veneer) was under $200.00 a pair! These monitors compare >quite favorably (actually better in my opinion) to the Rogers LS35A's. >A good friend of mine designed these little beauties (he has also >designed amps, preamps, subwoofers, etc.). They have a 3rd-order >Butterworth crossover, Thiel-Small cabinet alignments, rounded front >edges (reduces diffraction), 3/4" high density particle board, >fuses for both the mids and tweets, etc., etc. etc. The bottom line >is that they sound EXCELLENT! I am incredibly happy with them! >The best part is that *I* built them and I did a more careful job >than just about any other speaker manufacturer would do (my opinion). I am very glad that you obtained such a good result. There is indeed nothing like a job well done. But please tell us how your friend started the initial design. >>(....) But the danger is that you don't know what the final >>result will be until you connect the speaker to the amplifier. > >That's why when you are designing you need to have the crossover outside >the cabinet so you can fiddle the theoretical values to where they sound >the best (at least to your ears). Several comments: 1] You were already able to listen to similar speakers made by your friend. So you more or less knew the result. 2] Yes, finetuning the filters is a very good idea. But you fine tuned by ear I presume.Is this reliable? I guess you tune it to the sound you like best, which is of course what you ultimately want. 3] Unfortunately I must disagree that tuning your filters is the only parameter. How about annoying enclosure resonance? Can that be eliminated by tuning the filter? >>Add to this the amount of work and design that goes into making all this. >>If you don't have access to a whole range of instruments (pressure >> .... >>you are really walking in total darkness, and making wild guesses. > >Geeeez! What a pessimist ;-). Seriously though, it is a blast to make >your own speakers and I wouldn't worry all that much about all them >there fancy electronic equipment. Even if you only use the theoretical >cabinet volume and "text-book" crossover circuit, the result will >probably be better than 99% of the mid-fi junk out there (have you >ever looked at the inside of a Fisher loudspeaker????). Yes I have looked inside a Fischer loadspeaker, and I must agree that it really isn't too difficult to do much better than that. >>The result can be better than what you buy in a store, but it could be >>much worse too. > >Unless you are talking about GOOD speakers (read "Kef", "Rogers", "Linn", etc.) >I seriously doubt you could do much worse. Actually yes, I did have GOOD speakers in mind. >>One trick you could use is to "immitate" a speaker you like. > >Not such a bad idea actually. My friend who designed my monitors did >just that when he designed the subwoofer for the satellites. He >"immitated" the Audio-Pro B-250 subwoofer (a self amplified beast >with 2 Philips 6-1/2" woofers mounted in a "push-pull" configuration). >It is probably better than the Audio-Pro model (It has a much more powerful >amp of his own design with high quality components) and only cost about >$300.00 total (compared to over $1000.00 list for the A.P). > >>Don't forget that these speaker co.'s usually did a certain amount of >>research and have alot of know-how you don't have. > >ummmm........maybe....naw! (1/2 :-)) The "better" co's probably do (I know KEF does), but others, hmmm, hmmm! > [...] Well but do tell me a few more things. How did you design your Butterworth filter? From scratch or "Text book solution?". Did you actually measure if the filter worked correctly? How about the phase during cross over? Butterworth filters are pretty uniform in phase characteristic, but at crossover it is not unlikely to have two speakers working out of phase. Did you consider a phase correcting (all pass) filter to correct this? Does it matter? And what is your final result? How flat is your responce and what is the impedance of your final result along the frequency range? How about the efficiency? Do all these wonderfull characteristics matter at all to what sound quality you get? Well if you have other usefull tricks, please do share them Jan.