From: owner-bass-digest (Bass and DIY Loudspeakers Digest) To: bass-digest@lunch.engr.sgi.com Subject: Bass and DIY Loudspeakers Digest V2 #371 Reply-To: bass Sender: owner-bass-digest@lunch.engr.sgi.com Errors-To: owner-bass-digest@lunch.engr.sgi.com Precedence: bulk Bass and DIY Loudspeakers Digest Sunday, December 10 1995 Volume 2, Number 371 Important Addresses: Submissions to the list: bass@lunch.engr.sgi.com (or reply to this message). Adds/removes/archives: bass-digest-request@lunch.engr.sgi.com Real, live person: owner-bass@lunch.engr.sgi.com Topics: Re: Bass and DIY Loudspeakers Digest V2 #362 Re: Pioneer Subs Re: Cloning the NHT 3.3. Re: Dipole Subwoofers Re: Cloning the NHT 3.3. Re: Flame speakers Re: Bass and DIY Loudspeakers Digest V2 #370 Re: Dipole subwoofers Re: Dipole subwoofers Re: Flame speakers Re: New house for stereo Re: New house for stereo Re: Test Equipment ---------------------------------------------------------------------- Date: Sat, 9 Dec 1995 19:21:37 -0400 From: brian@mail.caribsurf.com (Brian Steele) Subject: Re: Bass and DIY Loudspeakers Digest V2 #362 >Better Driver: > >Pioneer IMPP TS-W252C >4 ohm voice coil >vented pole piece, double layer rubber surround and spider >Sensitivity 91db 1w/1m >Fs 27.2 hz >Vas 1.5 ft^3 (42.5 liters) >Qms 10.5 >Qes .36 >Qts .35 >Frq Respns 18-3500 hz +/- 3db >Pwr Hndlng 120w rms/400w max > Pioneer doesn't publish Xmax specs, which makes me wary of their drivers as there's no way of predicting power response. Also, Pioneer has a habit of predicting dubious low-end response for their drivers. The specs above produce the following alignments from my spreadsheet: Vas (cu. ft) = 1.50 Qes = 0.36 Qms = 10.50 Qts = 0.35 Fs (Hertz) = 27.2 Xmax (in) = ?.?? Re (ohms) = 4.00 Cone Dia (in) = 9.10 Power (W) = 400 Port Dia (in) = 2.50 Efficiency (dB) = 85.5 Band Pass sens. = 0dB Pioneer TS-W252C Vb Vf Vr Fb F3l F3h Lv ============== ===== ===== ===== ===== ===== ===== ===== Sealed (Q=0.7) = 0.49 55 55 Ported (B4) = 0.81 27 37 20.13 Ported (QB3) = 0.84 31 35 14.66 Ported (C4) = 0.82 30 35 16.49 Ported (Opt) = 0.94 31 33 12.42 BPass, Q=0.7 = 0.83 0.36 0.47 56 34 90 10.09 BPass, Q=0.6 = 0.59 0.26 0.32 65 38 112 10.09 APR, T=1.67 = 1.77 0.71 1.06 33 29 This looks like a driver built for sealed enclosures - for ported enclosures, the length of a port of sufficient diameter to avoid huffing and puffing (i.e. port noises) seems a bit on the long side. The 4th order BP looks interesting, though I'd probably try it with a larger port. The 55Hz F3 figure for the sealed enclosure makes it unsuitable for home use, but great for car use. Sensitivity seems a little on the low side, but box size is great. A good car sub (once the Xmax isn't ridiculously low). Brian Steele GRENTEL EMail: brian@caribsurf.com Phone: (809)440-1000 Ext. 291 ------------------------------ Date: Sat, 9 Dec 1995 19:21:43 -0400 From: brian@mail.caribsurf.com (Brian Steele) Subject: Re: Pioneer Subs >I don't know about how well it would go over for indoor use, but if you're in >the market for a good car sub, it's definitely worth listening to. BTW, they >also have 10" & 8" versions available. Also try the 1" pure carbon dome >tweeters. They're out of this world! > Interestingly enough, I find that Pioneer's older and cheaper tweeters sound better. I loved the sound of the TS-S20 series, an 8-ohm 92dB sens. 3/4" tweeter with a phase plug, and I still have my original set at home in a box somewhere. I had to use new Pioneer tweeters in my present car as the TS-S20s were too big (2" x 3" mounting), but I miss their sound - the new tweeters are too sibilant for my tastes. Boomers love these tweeters too - they can handle exceptional amounts of power without frying. Brian Steele GRENTEL EMail: brian@caribsurf.com Phone: (809)440-1000 Ext. 291 ------------------------------ Date: Sat, 9 Dec 1995 19:19:55 -0500 (EST) From: 92dyhein@wave.scar.utoronto.ca (DY HEINRICH) Subject: Re: Cloning the NHT 3.3. > On Sat, 9 Dec 1995, Ken Kantor wrote: > > > When I have more time, here's a fun little contest for A&S. Get some > > pro designers... I'll do it. We get given a 1" tweeter and 6.5" woofer > > from the A&S catalog at random. And 1 week. Entrants get 6 months and > > ANY 2-way drivers they want to use. Results are auditioned blind. > > A challenge has been laid down. Will the list respond? :-) > > -Tom Here's a response ... (yeah I know ... I won't stand a chance here against all you pros and all but since I am already thinking about building a pair for myself in the near future when I get some $$$ ready, why not? Hey, I play ball and is basically garbage man supreme so I'm very experienced in losing :) Heinrich 92dyhein@wave.scar.utoronto.ca ------------------------------ Date: Sat, 9 Dec 1995 19:34:05 -0500 (EST) From: 92dyhein@wave.scar.utoronto.ca (DY HEINRICH) Subject: Re: Dipole Subwoofers > Gee you must have missed Dy's plan on cardboard speaker boxes. Seriously, the > main focus here is on the practical, and cost issues. Sonotube seems > unbeatably cheap for a sub box, and MDF seems unbeatably good. Both are VERY > easy to work with, and generally proven to work. I resent that ... my cardboard speaker which I use for my computer is working fine up to now (still have no time to build a real box for it but for the volume level that's it's used ... no big deal ... no more vibration than those cheap "subwoofers" out there in the market (it's cardboard, stuffed, and lots of tape around it. Sounds pretty good for garbage ... tv speaker with some old xover parts I have lying around and a 1.5" cone tweeter from I don't really know where but it at least sounds better than those $100 albeit amplified multimedia speakers at the local Future Shop ... I think :) > Anybody try building some flame speakers recently? Very efficient, but maybe > not a good choice for use in cars. How about an old 6.5" woofer pair from Hondas (friend upgraded their car speakers ... they're in really bad shape). I cut off the wizzer cone and the cloth surround and added some mass to the cone to stiffen it up (paper and white glue). Never measured it yet but I can get much more bass out of it now in the same cardboard test box that I am using (relatively large for a 6.5" woofer) .... I have to now find something to make the foam I am using not too leaky (foam from office chairs). I know that fs if much smaller now but I can't even begin to immagine how large the Qts is now. I was at first thinking that I could maybe try to revive them and use them as little bass modules for maybe my computer to extend the output to say 60 or 80Hz but they are really inefficient now ... maybe if I cut off the spider to give it a and lossy linear suspension (it seems to go back and forth pretty far before it hits the back plate and I really couldn't care less if I kill them). Please don't respond to this. This was just something I was playing around with at 2:30am while studying for my calculus exam. I have totally ignored it now (maybe when studying for my next exam). Heinrich 92dyhein@wave.scar.utoronto.ca ------------------------------ Date: Sat, 9 Dec 1995 19:08:57 EST4EDT From: jdudeck@zenia.simcsg.sim.org Subject: Re: Cloning the NHT 3.3. > On Sat, 9 Dec 1995 jdudeck@zenia.simcsg.sim.org wrote: > > Personally I have yet to hear a 3.3, or much at all in the "high-end" world. > > I hope I have the opportunity sometime. > > This really surprises me. I know that most of us say that we use live > music as the reference against which we design, build or buy but how can > one ignore what's out there already? I don't know if you are typical, in > this respect, of others on this list. If so, then I am not. I can't speak concerning the demographics of this list. As for myself, I point out that speaker building as a hobby does not automatically imply interest or familiarity with "high-end" products any more than boating as a hobby implies interest in yachts. Well, maybe a little bit more. After all boating is a much broader field than speaker building. I came into this from the technical side, not from the consumer side. I am not well-to-do and have never had a strong desire to venture into boutiques of any sort. I have done work in broadcast audio engineering and quite a bit of sound reinforcement work. Now that I've taken an interest in speaker building, there is a natural corollary which is the quest for perfection. This tends to draw one's interest more and more towards the more expensive products. Still I don't find I have a strong desire to go searching out the showrooms of the high-end dealers. I have an aversion to asking them to spend their time and effort to demonstrate products that I have no intention of buying. John Dudeck Home: jdudeck@zenia.simcsg.sim.org Tel: 704-588-9891 Work: jdudeck@simcsg.sim.org Tel: 704-588-6100 - -- "I'd rather E-mail than eat. You'll believe me when you see how "dry" I am. (Dry is Liberian for skinny)." -- Cork Loken ------------------------------ Date: Sun, 10 Dec 1995 10:23:41 +0000 From: Zvon Ponos Subject: Re: Flame speakers Tom McMinn asked about "flame speakers" Mike Ford mentioned. Perhaps Mike reffered to plasma tweeters manufactured by Magnat in late 70's. Nice highs, lots of hiss, lots of ozone smell (very, very expensive). They would be favorite Shirac speakers (radiation). Regards, Zvon ------------------------------ Date: Sat, 9 Dec 1995 20:44:17 -0600 From: Dylan-Bob@mail.utexas.edu (Dylan Kelly) Subject: Re: Bass and DIY Loudspeakers Digest V2 #370 >Many integrated amps and receivers come with a headphone output. Sometime >back I used one of those Discman mini to RCA converter and mini to headphone >jack adapter to feed from the headphone output on the main amp to line-in on >the bass amplifier. It seemed to work OK at the time. Radio Shack (ugghh!) has a 1/4" headphone jack male to 2 RCA females for around $2. I am suffering through the same setup at the moment, except I had to throw on attenuator between the head phone jack and my sub amplifier. Dylan J. Kelly _ ___ _ BSEE University of Texas at Austin \\_____/ \_____// 1995 Southwest Conference Champs \_____|O O|_____/ Hookem' Horns \ / \_/ BEVO (_) ------------------------------ Date: Sun, 10 Dec 1995 11:46:20 +0000 From: Zvon Ponos Subject: Re: Dipole subwoofers Hmm, a pint of cold Emy Drought or Redback Bitter would help on Sunday morning and 30 degC. Mike, have you ever seen an ELS speaker "arcing in a ball of fire" due to contact between a membrane and stators? My speakers survived strong draft (intentional and unintentional) a number of times. A "snap" is followed by a temporary loss of volume (panels are recharging) and that's it. High resistance coating limits arc current and generated heat. I could imagine problems with an aluminium or very low resistance membrane, because whole panel charge would be dissipated instantaneously (big arc, lot of heat). I still have to check longevity of my ELS's. They have been in operation for about 6 months. Membrane replacement is not difficult. It takes me an afternoon to stretch, glue and coat one panel. "Quad ELS isn't stretched tight, it just sort of hangs between the charged panels". If the membrane is not stretched tight you wouldn't hear a sound except perhaps constant flapping back and forth between stators. Sufficient membrane tension is essential for ELS operation. Sorry Ken Kantor, but I think that DIY speaker builders are now in better position than 5-10 years ago. A common PC with soundcard can perform basic acoustical/electrical measurements of a loudspeaker. DIY bulders can mesure actual response in their listening rooms and fine tune their systems. Comercial speakers are built for "generic" rooms, their shape and box materials must be acceptable for an "average" purchaser. As an example I have analysed simply supported plate of 2 in structural plywood and 1.5 in thick concrete (with and without bracing). Looked both at natural frequencies and amplitude due to harmonic excitation. If you are interested I can send you FEA plots (finite element analysis plots showing some interesting numbers and shapes) in a couple weeks (after my holiday). I am also sure that craftsman like Lou or Dan could make nice enclosures. It is also cheap. Concrete can be polished and than you have terrazzo. Check price of terrazzo tiles. Exposed aggregate finish could be done with ordinary garden hose. Shapes are limited only by imagination. Glueing and bolting are not problem. Marble and granite also look nice. DIY is not about profit. It is about experimenting and fun. It is also expensive. Regards, Zvon ------------------------------ Date: Sun, 10 Dec 1995 00:41:40 -0800 (PST) From: Mike Ford Subject: Re: Dipole subwoofers > > Mike, have you ever seen an ELS speaker "arcing in a ball of fire" due to Nope, I was waxing poetic. > resistance coating limits arc current and generated heat. I could imagine What do you consider "high" resistance? A off the top of my head estimate, for something like mylar rubbed with graphite, maybe 20k ohm/some distance. With a 4kv charge, current would be about 200 ma, and power about 800 watts, which tells me I must have this all wrong. > > "Quad ELS isn't stretched tight, it just sort of hangs between the > charged panels". > If the membrane is not stretched tight you wouldn't hear a sound except > perhaps constant flapping back and forth between stators. Sufficient > membrane tension is essential for ELS operation. Why? and no it isn't. > > Sorry Ken Kantor, but I think that DIY speaker builders are now in > better position than 5-10 years ago. A common PC with soundcard can > perform basic acoustical/electrical measurements of a loudspeaker. DIY Better, yes, pretty good, sure, competitive, nyet. The small quantity market (us) must lag about 5 years behind the big guys in new driver technology. With the exception of car audio, all the neat new stuff gets shown to the big users, and the first we even hear of it is in the press release for the finished speaker. Maybe less than 5% of the drivers ever drop down into the small user market even after several years. People like Ken have the volume to get places like Tonegen to build them a driver to meet their spec. > > I am also sure that craftsman like Lou or Dan could make nice enclosures. > It is also cheap. Concrete can be polished and than you have terrazzo. The most important thing is the sound of the driver. Next maybe crossover. Way down in the dust is the improvement possible beyond well braced MDF via alternate cabinet materials. > bolting are not problem. Marble and granite also look nice. DIY is not > about profit. It is about experimenting and fun. It is also expensive. Everybody needs a hobby, but I am more into sound than sawdust. Subwoofer make a good DIY thing because the market is small and new enough that the big guys don't have their usual advantages. Design and construction are well defined ( the physics are simple). And number one, commercial products are often lacking in some desired area even at higher price points. ------------------------------ Date: Sun, 10 Dec 1995 01:11:46 -0800 (PST) From: Mike Ford Subject: Re: Flame speakers > > > Anybody try building some flame speakers recently? Very efficient, but maybe > ^^^^^^^^^^^^^^ > > I have not heard of these. What are they? > First the good news, they are something like 20 to 30% efficient (typical drivers are well below 1%). The bad news is that all example I have seen have been either flawed, or dangerous. The best sounding may have been built by Jon Iverson (the extremely weird guy behind I think Electron Kenetics that disappeared a few years ago). They used a strong RF field to ionize the air, which could then be forced to move directly via charges applied to grids. The only person I have personally met that listened to them said that they sounded better than anything, but one little caveat. He is a psychologist working in the field of electrical study of the brain, and he claims that exposure perhaps to the RF permanently altered his brain wave pattern. The other rumor about them was that during a test a hole was accidently blown in a wall of the lab. BTW they are called flame speakers because a simple way to ionize air is with a flame. ------------------------------ Date: Sun, 10 Dec 1995 01:47:46 -0800 (PST) From: Mike Ford Subject: Re: New house for stereo > > > The single most significant improvement you can make in the design of a > > new room is to build a cathedral ceiling. Presuming the floor is > > Cathedral ceilings? That's a little excessive for a house isn't it? In modern houses, cathedral ceiling just means no attic crawl space and the ceiling follows the roof line. It may even be cheaper than a flat ceiling. ------------------------------ Date: Sun, 10 Dec 1995 02:02:09 -0800 (PST) From: Mike Ford Subject: Re: New house for stereo > > The single most significant improvement you can make in the design of a > new room is to build a cathedral ceiling. Presuming the floor is I was just thinking, sure great idea, then fitting the room into the whole house design fluttered through my mind. Assuming something like a 16x21 room it gets pretty likely the short dimension will have the exterior wall so my ceiling ends up sloping from right to left, not front to back. Other than making me crazy I wonder how that will effect the sound? BTW due to my own perverse nature I would likely use a drop ceiling at a more gentle slope and the way I want it to slope. ------------------------------ Date: Sun, 10 Dec 1995 11:37:18 -0500 From: VenableJR@aol.com Subject: Re: Test Equipment >The IMP system uses a printer cable to talk to the outboard A/D box and >hence works well with notebooks where you cannt get a good soundcard to do >your conversion like many of the systems designed for table-top computers. I >figured I could now really dial in my crossover and see what my cabinet >modifications are doing to the speaker output. I loaded the software and >gave it a spin, but nothing happened, bummer. I tried a couple of different >printer cables and the two desktop pentiums in my office, but no go. I will >try to have Old Colony send me another unit to try early next week if they >have one built up. BTW, you can save some money on the IMP by getting it in >the kit form, which I did not do because I wanted to make sure it was >working properly (oh well). Does anyone have any experience with the IMP FFT >based analysis system? > >Ed Devlin I have a little bit of experience using the IMP. Although I don't have an IMP system I have used designer, Bill Walso's setup in tweaking. In your situation it sounds like a bad "box". Bill just designs he doesn't build. He subcontracts all of that work out to a local house wife. I haven't heard of many failures though, mostly system incompatibilities. As for the IMP system, its one of the most useful programs for the DIY market. The cycling feature will let use change values of the crossover and seeing the changes in response, instantly on your monitor. I’m finally going to purchase the Liberty Audiosuit, a much expanded version of the IMP. Bill is working on a full RTA and its going to be added in the near future to the Audiosuit system. A complete system for pennies, actually around $600. A small price considering the alternatives. If anyone else has questions about the Liberty systems I can probably answer them.....if not I’ll ask Bill for ya. Joe Venable VenableJR@aol.com ------------------------------ End of Bass and DIY Loudspeakers Digest V2 #371 *********************************************** A non-digest (direct mail) version of this list is also available; to subscribe to that instead, send the command lines: unsubscribe bass-digest subscribe bass end in the body of a message to majordomo@lunch.engr.sgi.com. Thanks and enjoy the list!