From: owner-bass-digest (Bass Appreciation Digest) To: bass-digest@lunch.engr.sgi.com Subject: Bass Appreciation Digest V2 #112 Reply-To: bass Errors-To: owner-bass-digest@lunch.engr.sgi.com Precedence: bulk Bass Appreciation Digest Friday, March 31 1995 Volume 2, Number 112 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: Cabinet Joints? Re: Amplifier power in half rated impedance. WasRe: Numark Re: Has anyone heard of Numark amp?? Re: Bob Carver's new amp Re: Cabinet Joints? Cabinet making. RE: Cabinet Joints? Re: Cabinet Joints? Re: Cabinet making. Re:Has anyone heard of Numark Amp? Re: Cabinet making. Re: cheaper alternates.. dorm lifestyle RE: Cabinet making. ---------------------------------------------------------------------- From: ledzep@elmo.lz.att.com (Carl Muhlhausen LZ 1B-115L x3052) Date: Fri, 31 Mar 1995 08:33:32 -0500 Subject: Re: Cabinet Joints? > From lunch.engr.sgi.com!owner-bass@ig2.att.att.com Thu Mar 30 23:20 EST 1995 > Date: Thu, 30 Mar 1995 21:43:51 -0600 > Mime-Version: 1.0 > To: bass@lunch.engr.sgi.com > From: wkdixon@students.wisc.edu (The "Mad" Trumpeteer) > Subject: Cabinet Joints? > > > Hello Bass list, > > I have a question towards the persons who have designed their cabinets. > What type of joints do you use? I am curious because I have studied > woodworking for a little bit. I have seen things like dove tails to make > joints, but there has got to be an easier way than this. Also, I can't see > just putting glue on the top of the board and sticking it to the wall as > being the strongest. (I'll try to draw an ascii pic if you don't quite > understand.) > > Thanks for your input. > > > I've had good luck with a rabbett joint, which I'll try in ASCI ____ _____________________ | | - - <-- | \ | |___ glue here |____ / | | ---> | | | |_____________________\ | | | | I also used screws to hold the joints together while the glue sets. Also if you cut the rabbetts (TS or router) so the upper lip is a little long, you can go over the finished joint with a router trim bit and finish off the joint so it's perfectly square. _ ******************************************************************************** Carl W. Muhlhausen Note new id--> ledzep@elmo.lz.att.com Rm. 1B-115L (908)-576-3052 AT&T Bell Laboratories 307 Middletown-Lincroft Rd. Lincroft, NJ 07738 ******************************************************************************** > > ------------------------------ From: perley@cadence.com (Don Perley) Date: Fri, 31 Mar 95 5:54:25 PST Subject: Re: Amplifier power in half rated impedance. WasRe: Numark > If connected to a 4 Ohm load the current doubles, the voltage sving > doesn't change (if it's a good amp - and don't flame me for this !!) > and thus the power doubles . Easy heh ? To meet the laudable goal of being able to drive various (or varying with frequency) impedances, generally yes. If you are pushing the power limits of the amp, then you have to decide which corners to cut. In some sense, making an amp which delivers the same maximum voltage at 8, 4, 2, ohms is an excersize in doing the best you can under artificial constraints.. sort of like the old America's Cup 12 meter yacht rules. You don't get all the benifit you could for the money. If you are going to sink all the resources into the current capabilityy to deliver 50 volts into 2 ohms then you are better off getting more voltage at 8 ohms rather than constraining your self to 50 (and much less power). Note that by "getting more voltage" I mean the clipping limit, not that the gain changes with impedance. To put it another way.. for the same money would you rather buy a "rock solid" 100 watt amp which gives 400 watts at 2 ohms, or a "wimpy" 300 watt amp which gives 400 watts at 2 ohms but exceeds the envelope of the first amp at any other impedance? - -Don Perley ------------------------------ From: ledzep@elmo.lz.att.com (Carl Muhlhausen LZ 1B-115L x3052) Date: Fri, 31 Mar 1995 09:00:58 -0500 Subject: Re: Has anyone heard of Numark amp?? > >> The ignorance is in not knowing that a "good" design can have a rating into > 8 ohms that is significantly more than half the rating into 4 ohms e.g. 40% > more. I use quotes around the word good because it has to be defined in > some way. I think the most appropriate definition is to maximize value > (quality and power) for money. This definition does not require at least > the first if .. then statement you made. Isn't there a strong correlation with these ratings and the overall quality of the amp though? You have your typical bells and whistles receiver 100 watts into 8 ohms, not rated/don't use into 4 ohms vs a real amp 100 watts into 8 ohms, 190 (or so) into 4 ohms. In terms of "quality" and not necessarily bang for the buck, the latter is a better amplifier. Whether it's extra cost (if any) is justified really depends on what your going to use it for. Given that I like to play around with different speakers, I'd hate to have to get a new amp just because my new speakers are 4 ohms rather than 8. It's seems to me that there are plenty of receiver/amps out there designed to deliver their rated power into an 8 ohm resistor and nothing else and that these fall into the lower quality category. Ratings into lower impedance loads give a good indication of what kind of tradeoffs the manufacturer made in the design (e.g. 5 band color coordinated graphic equalizer vs. a larger power supply). Carl ******************************************************************************** Carl W. Muhlhausen Note new id--> ledzep@elmo.lz.att.com Rm. 1B-115L (908)-576-3052 AT&T Bell Laboratories 307 Middletown-Lincroft Rd. Lincroft, NJ 07738 ******************************************************************************** ------------------------------ From: perley@cadence.com (Don Perley) Date: Fri, 31 Mar 95 6:07:23 PST Subject: Re: Bob Carver's new amp > > On Thu, 30 Mar 1995 gt3003a@prism.gatech.edu wrote: > > > Are you talking about the Sunfire amp? It has been reviewed in > > one of the magazines. Its specs look a lot like the Carver Research > > Lightstar Reference. Big surprise! I'll bet the Sunfire design is better > > though. It is considerably cheaper than the Lightstar Reference if I > > remember correctly. My dealer picked up some info at the Montreal show.. give this all the credit that third hand rumors deserve: The "carver the man" amp is close to what what they had when Bob split off. The "carver the company" amp is more of a debugged, finished product. - -Don Perley ------------------------------ From: "Bill Flowers" Date: Fri, 31 Mar 1995 10:04:57 -0500 (EST) Subject: Re: Cabinet Joints? > I have a question towards the persons who have designed their cabinets. > What type of joints do you use? I am curious because I have studied > woodworking for a little bit. I have seen things like dove tails to make > joints, but there has got to be an easier way than this. Also, I can't see > just putting glue on the top of the board and sticking it to the wall as > being the strongest. (I'll try to draw an ascii pic if you don't quite > understand.) While you can use rabbet joints or splines, as I've proven with my NHT1259 subs it isn't necessary. I used simple but joints which were thouroughly glued and screwed approx. every 4" (to clamp them while the glue set). I also ran a fillet of glue on the inside edge of each joint for additional strength (and to be double-sure that it was air tight). Since it is the glue which is holding things together (once it dries), you can remove any screws which might be in the way of any exterior finishing treatment you might be doing (such as along an edge which you are going to bevel). This is the KISS priniciple applied to speaker cabinet construction. Since no one will see the joints anyway, so long as the are strong and air tight who really cares how fancy you get? If that's how you want to spend your time, that's fine. I'd rather spend my time listening to the finished product. :-) P.S. With that octahedral cabinet someone mentioned I can understand the use of spline joints. But for right-angle joints, what I did will give more than adequate strength (if the cabinet is properly braced -- and if it isn't you'll have other problems anyway) and be properly air tight. - --- W.A. (Bill) Flowers waflowers@qnx.com QNX Software Systems, Ltd. phone: (613) 591-0931 (voice) 175 Terence Matthews (613) 591-3579 (fax) Kanata, Ontario, Canada K2M 1W8 ------------------------------ From: 92dyhein@wave.scar.utoronto.ca (DY HEINRICH) Date: Fri, 31 Mar 1995 10:04:48 -0500 (EST) Subject: Cabinet making. I have just bought an MDF sheet and had the place cut them to size for me ... unfortunately, I wasn't really thinking when I made my plans. Now, my box would have 2 panels that are 24"x36" ... anyone here have any ideas as to how I would brace these panels or would this just simply be a lost cause. I am using 3/4" MDF wood. The smallest I could really bring it down to though without affecting sound too much is around 24"x24" .... should I bother or should I just make the box as is (in terms of bracing and cabinet stiffness and all)? Help! Has anyone actually build a sub with these big sheets and still have them being strong enough? 92dyhein@wave.scar.utoronto.ca ------------------------------ From: Lou Lung Date: Fri, 31 Mar 95 09:27:00 E Subject: RE: Cabinet Joints? wkdixon@students.wisc.edu (The "Mad" Trumpeteer) writes : >> _____ _____________________ >>| |--> <--| \ >>| |glue here| / >>| | |_____________________\ >>| | >>| | This is called a "butt" joint, and is in many ways just fine for building subs. There are many other alternatives. cwittenb@ux4.cso.uiuc.edu mentioned the use of a spline and mikeford@kaiwan.com mentioned the rabbet (not rabbit !) joint. Since speakers are made of panels, other potential joint types include dovetails (as you mentioned), sliding dovetails, various dadoed/grooved mortise and tenon joints, and even biscuited joints to list a few. But there are other practical aspects that limit what you can and should do. One limitation is the chose of working material. We tend to use medium density fiberboard (MDF) for speaker enclosures. MDF is a man-made material made up of fine wood particles and glue, pressed into sheets under pressure. It has no grain orientation and is relatively stable under changing environmental conditions. Many of the traditional woodworking joints are used in areas where wood movement and the existence of grain direction can be a problem. MDF has no such restrictions so you have more choices over joint types. So you can still do a full dovetailed MDF box if you wish, but it'll be a waste of time (unless you are really good and enjoy the work !). Speaker cabinets also have invisible interiors, so it doesn't matter if you have all kinds of reinforcement on the inside that would otherwise look horrible when making a china cabinet. It is not uncommon to add various braces to the butt joints and with no cross-grain glueing problems, such joints are very strong. Since most people add an additional exterior veneer or veneered panel over the MDF, you can also use mechanical fasteners from both the inside and outside for added strength. Again, it doesn't matter if it's unsightly 'cause it'll be covered up. Boxes also have to be air-tight, so joints with lots of glue and caulk are used. Woodworking has been my hobby for a few years, and I enjoy making the traditional wood joints. For example, my European styled workbench trestle base has hand cut through-mortise & tenoned joints and is rock solid. But my speaker boxes have been butted or rabbetted MDF. I've also used screws & biscuits for alignment on some boxes. You can really use any joint you like. Just make sure you have enough glue. Ultimately, with the box together, the joints will be far stronger than you need. What it boils down to is to ask yourself what joint you are comfortable with making using the tools available to you. Use that joint then proceed with the necessary steps for speaker building (caulking, bracing etc; some of which may have to be planned ahead of time like any woodworking project) and you'll do fine. good luck -lou ------------------------------ From: Bob Neidorff Date: Fri, 31 Mar 1995 10:47:32 -0500 (EST) Subject: Re: Cabinet Joints? > From: wkdixon@students.wisc.edu (The "Mad" Trumpeteer) > Date: Thu, 30 Mar 1995 21:43:51 -0600 > Subject: Cabinet Joints? > > Hello Bass list, > > I have a question towards the persons who have designed their cabinets. > What type of joints do you use? I am curious because I have studied > woodworking for a little bit. I have seen things like dove tails to make > joints, but there has got to be an easier way than this. Also, I can't see > just putting glue on the top of the board and sticking it to the wall as > being the strongest. I agree. Glue goes into a tightly fitting joint. That makes a strong joint. You can use glue as a sealer after making the joint, but all that will do is eliminate minor air leaks. This is valuable, especially for sealed box enclosures, but adds no strength. I find that simple butt joints with cleats are strong enough for speakers. Lots of the fancy joints in woodworking journals and cabinet shops are designed for solid wood. Most speaker builders use materials like MDF, which don't dovetail well, and have different strength trade-offs. In general, with MDF, the thicker the wood, the better, so dovetails and rabbets that thin the board are detrimental. Biscuits and dowels are a better choice. However, large cleats on the inside are still the best solution, as they give massive glue joint area and don't weaken the basic structure. I built a pair of maple speakers. Boy was that a mistake. I waited a long time between glueing together the boxes and finishing them. During that time, humidity changes caused the boxes to shrink and split. I filled the splits with epoxy, sanded it smooth and the result has been stable and good sounding to this day, five years later. However, I won't do that again. Next time, back to MDF and veneer. - -- Bob Neidorff; Unitrode I. C. Corp. | Internet: neidorff@uicc.com 7 Continental Blvd. | Voice : (US) 603-429-8541 Merrimack, NH 03054-0399 USA | FAX : (US) 603-424-3460 ------------------------------ From: "Bill Flowers" Date: Fri, 31 Mar 1995 11:12:04 -0500 (EST) Subject: Re: Cabinet making. > Now, my box would have 2 panels that are 24"x36" ... anyone here have > any ideas as to how I would brace these panels or would this just simply > be a lost cause. I am using 3/4" MDF wood. The smallest I could really > bring it down to though without affecting sound too much is around > 24"x24" .... should I bother or should I just make the box as is (in > terms of bracing and cabinet stiffness and all)? If those panels are the sides, and they are to be 36" high and 24" deep, then the details on bracing I'm going to be sending you will work just fine. OTOH, if it is 24" high and 36" you're going to have problems that can only be solved (if at all) with some serious, complicated bracing. > Help! Has anyone actually build a sub with these big sheets and still > have them being strong enough? My subs are about 24" front-to-back. No problem. - --- W.A. (Bill) Flowers waflowers@qnx.com QNX Software Systems, Ltd. phone: (613) 591-0931 (voice) 175 Terence Matthews (613) 591-3579 (fax) Kanata, Ontario, Canada K2M 1W8 ------------------------------ From: Val C Valenzuela Date: Fri, 31 Mar 1995 08:09:11 -0600 Subject: Re:Has anyone heard of Numark Amp? Actually Numark is not the big electronics parts place. That is company's name is "Newark". Numark was one of the best name brand if you were a d.j. in the good ol'early 90's. They had, my opinion and my friends, the best mixers with multiple channel inputs and outputs out for commercial use. I believe the guy that designed their electronics, moved on to create d.j. and band entertainment type equipment for MTX electronics. MTX is based in Rockford,IL. Big company that produces mostly car audio electronics. Bottom line. I have never heard of their Numark amps. The name brand is very familiar and excellent as far as reliability. I would guess that those amps are not geared for home use also. V.V. @ __@ ,_ Motorola, CIG __@ /\,_ _`\<,_ _\ \@ _`\<,_ -|~(*) (*)/ (*) (*)'<_ (*)/ (*) (*) http://www.cig.mot.com (*) ------------------------------ From: 92dyhein@wave.scar.utoronto.ca (DY HEINRICH) Date: Fri, 31 Mar 1995 11:44:52 -0500 (EST) Subject: Re: Cabinet making. > If those panels are the sides, and they are to be 36" high and 24" deep, > then the details on bracing I'm going to be sending you will work just > fine. OTOH, if it is 24" high and 36" you're going to have problems that > can only be solved (if at all) with some serious, complicated bracing. I don't really know how to position them as yet (and as such don't know where to make the 11" hole yet, but it won't be at the 24"x36" panels for sure. What's the difference between the where I put the panels anyways? I was sort of thinking of using the 24"x36" panels as the top and bottom (since the bottom is laying flat against the carpet with the whole cabinet weight on it, I would suspect it's stiffness to be not as critical). > > Help! Has anyone actually build a sub with these big sheets and still > > have them being strong enough? > > My subs are about 24" front-to-back. No problem. How hight and wide are they? I am kinda feeling stupid making a 7 cuFt box (24"x36"x16") ... don't ask me how I came up with the dimensions ... 92dyhein@wave.scar.utoronto.ca ------------------------------ From: "jerry (j.) quinn" Date: Fri, 31 Mar 1995 10:29:00 -0500 Subject: Re: cheaper alternates.. dorm lifestyle I bought my sonotube at a home improvement type of place. An 18" diam tube 12 ft long cost me about $50 Can. Jerry Quinn jquinn@bnr.ca ------------------------------ From: Lou Lung Date: Fri, 31 Mar 95 12:18:00 E Subject: RE: Cabinet making. DY HEINRICH <92dyhein@wave.scar.utoronto.ca> writes : >>Now, my box would have 2 panels that are 24"x36" ... anyone here have >>any ideas as to how I would brace these panels or would this just simply >>be a lost cause. I am using 3/4" MDF wood. Assuming these sheets represent 2 dimensions of your sub, you can definitely brace this. Keep in mind though that no matter how much you brace the box, you'll always wonder if you could have done more. Having said that, one way to brace this very stiffly would be to add "shelves" made of plywood at regular intervals. If you are accurate in cutting, you can butt these to the sides on the interior. If you're not as accurate, cut dadoes into the sides, size the shelves just under the needed size (accounting for dado depth) and use the difference in size for an error margin. Either way, use lots of glue to ensure a good seal. On each shelf, cut out various holes to leave behind a stiff grid-like structure. Since your box is large in 2 dimensions (24 and 36 inches) you may have to do this sort of bracing along both axis. This can get hairy, and potentially heavy. The LDC has a chapter on this I believe. good luck -lou ------------------------------ End of Bass Appreciation Digest V2 #112 *************************************** 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!