http://techtalk.parts-express.com/blog.php en Mon, 20 May 2013 04:12:52 GMT vBulletin 60 http://techtalk.parts-express.com/images/misc/rss.jpg http://techtalk.parts-express.com/blog.php http://techtalk.parts-express.com/entry.php?231-Question-About-Power-Inverter Mon, 14 May 2012 00:59:52 GMT I just bought a 3000 watt continuos power inverter and am running a portable air conditioner that has 840 watts.Well ...its works for about 5 minutes... I just bought a 3000 watt continuos power inverter and am running a portable air conditioner that has 840 watts.Well ...its works for about 5 minutes ,then shows a low voltage reading.Does this mean the battery in my my ford windstar is not powerful enough?...do i need to buy a bigger battery with more amps? ]]> brian t http://techtalk.parts-express.com/entry.php?231-Question-About-Power-Inverter http://techtalk.parts-express.com/entry.php?230-HELP-I-want-to-make-a-powered-speaker-tower Mon, 07 May 2012 22:36:58 GMT I want to build a speaker tower all powered by the Dayton Audio MCA2550E 2.1 Channel Class D Amplifier. I was just going to build in a pair of the... I want to build a speaker tower all powered by the Dayton Audio MCA2550E 2.1 Channel Class D Amplifier. I was just going to build in a pair of the Dayton Audio B652 6-1/2" 2-Way Bookshelf Speakers directly to it. I was going to use the sub output on the amp to power a Goldwood GW-8024 8" Butyl Surround Woofer at the bottom of the tower in a sealed box. Will all of these together make a a tower that can produce a decent amount of sound at high levels? Or will that amp have trouble pushing those speakers or sub to louder levels? ]]> 315andy http://techtalk.parts-express.com/entry.php?230-HELP-I-want-to-make-a-powered-speaker-tower http://techtalk.parts-express.com/entry.php?222-a-little-something-for-Indiyana-2012-hopefully Wed, 04 Apr 2012 21:59:41 GMT Attachment 26910 (http://techtalk.parts-express.com/attachment.php?attachmentid=26910)1 1 ]]> UGP http://techtalk.parts-express.com/entry.php?222-a-little-something-for-Indiyana-2012-hopefully http://techtalk.parts-express.com/entry.php?217-Fuse-for-VEI-V-989OA Fri, 23 Mar 2012 01:48:33 GMT I blew the fuse on my little sequencer, and it's a tiny, unmarked one that's soldered in. Does any one know the amp rating? Any suggestion on improving the design? I was thinking of adding an external fuse holder in case I overload it again. I use it for animated rope light sculptures. Thanks. ]]> willyphixit http://techtalk.parts-express.com/entry.php?217-Fuse-for-VEI-V-989OA http://techtalk.parts-express.com/entry.php?216-My-Repair-Shop Thu, 22 Mar 2012 12:01:59 GMT I have a corner in the cellar of my home set aside for repairing speakers. Most of my repair work is done there. Some of the larger speaker... I have a corner in the cellar of my home set aside for repairing speakers. Most of my repair work is done there. Some of the larger speaker repair/restoration jobs are done on the first floor.
Here is picture of my work bench. There is a darkroom timer (top center) that's left over from a darkroom I once had in that same spot. On the left side of the pic, a set of plastic clamp rings can be seen. They are used with spring clamps to hold down fresh refoams and/or when gluing down gaskets.
Below that is a scan of my reconer's certificate from the PLRA.



]]> carlspeak http://techtalk.parts-express.com/entry.php?216-My-Repair-Shop http://techtalk.parts-express.com/entry.php?214-Metal-cones Mon, 19 Mar 2012 14:49:10 GMT What’s wrong with metal cones? Nothing. It’s the crossover (that’s the problem). Metal cones and “soft” cones require different treatment . . .... What’s wrong with metal cones? Nothing. It’s the crossover (that’s the problem). Metal cones and “soft” cones require different treatment . . . most crossovers that seem adequate with soft cones simply will not sound good with metal.

All cones break up (for a number of reasons, and in a number of ways). All cones beam (some more than others). Soft cone drivers address the issues with internal damping and “controlled” decoupling, to greater or lesser success . . . and sometimes designers incorporate the resulting cone behavior into the design of the crossover itself. With metal cones the *only* approach to breakup that works is avoidance. Complete and total avoidance. For metal cones incorporating the “breakup” behavior into the crossover fails in some pretty fundamental ways. One doesn’t see that mistake often with the SEAS Excel drivers, for example, because their first breakup produces an obvious (and nasty) peak. Just look at it and it screams “keep off me”.

Not so with the Dayton RS series drivers (RS225, RS180, RS150). Their first breakup produces a null. The natural (but false) assumption is “won’t hear it”, and the common mistake that follows is “treat it as part of the filter curve”, following the habit established with soft cones. One common result is a supposedly LR4 (acoustic) filter composed of a combination of a 3rd order electric filter and the “natural roll off” of the driver. And this often tempts the designer to push the crossover frequency *up* to better take advantage of the better-looking-on-paper response curve that results. But there really is no “natural roll off” with metal cones . . . there is just the on-axis (acoustic) null that is but one symptom of a nasty cone breakup. And moving the crossover frequency up only makes things worse . . . there’s more signal getting through to drive the breakup.

There are three simple rules for getting the best from Seas metal cones, and they apply to the Daytons as well: cross no higher than one third the first breakup frequency, cross LR4 electric, *and* put a notch filter on the first breakup (whether it’s a peak or a null) because the first two rules alone are often not enough . . . with a metal cone it is *critical* that there be no signal present to drive cone breakup. Such filters are easy to implement “active”, but become expensive in “passive” designs (although one can sometimes “fudge” a little on the second rule if the notch is carefully done, and one sometimes sees a cauer elliptic filter, or an electric 3rd plus a notch working reasonably well). But it makes the Baby Jesus cry to see a RS150 crossed 3rd order at 2kHz . . . if you’re going to do that use a AC130 instead . . . ]]> Deward Hastings http://techtalk.parts-express.com/entry.php?214-Metal-cones http://techtalk.parts-express.com/entry.php?211-measurement Fri, 03 Feb 2012 20:03:35 GMT Quote:
orginally Posted by johnnyrichards
"Now, the fun part - correlating the squiggles with what you like to hear"

Yep . . . problem is we generally don't measure what we hear.

There are, somewhat generally speaking, three frequency response curves that matter. The forward "on axis" curve that we typically design to is just a small part of what defines how a loudspeaker sounds, although it often comes close (if one ignores diffraction) to describing direct radiation into the listening area. Note "listening area" as opposed to "sweet spot" or "test point".

After that comes frequency response at the angle which provides first reflection into the listening area (which our ear typically treats as part of the "direct" sound). What angle(s) that is depends on placement and toe-in, and how it sounds is heavily influenced by "treatment" at the reflection points. The room has become a part of the loudspeaker.

Third there's the overall power response. For most rooms and listening positions this multiply reflected sound is the major contributor to the sound we hear, and establishes our sense of overall frequency response. If it differs considerably from the direct sound we unconsciously attribute the difference to the room, although if we are familiar with the room we may recognize, and correctly identify, the speaker's contribution. That's one of the primary indicators that lets us tell "real" from "reproduced" (and judge the overall quality of a loudspeaker). But once again the room, or more accurately the room's absorbtion response, becomes a part of the loudspeaker.

And then there's the whole question of "distortion" . . . what we hear, what we don't hear, and what we measure. The simple harmonic distortion curves that make up 99% of the published distortion measurements represent, except at the extremes, distortion that we don't hear in music reproduction because of masking and the presence of those same harmonics occurring "naturally". The curves are useful only as proxies that show a driver's limits and hint at (indirectly represent) the distortions that we do hear (but rarely measure).

It's always a good idea to take a mental "step back" and ask "what am I measuring, and what does that have to do with what I really want to know?" . . . ]]> Deward Hastings http://techtalk.parts-express.com/entry.php?211-measurement http://techtalk.parts-express.com/entry.php?205-Experiments-on-making-own-drivers Mon, 19 Dec 2011 15:30:51 GMT So I think I'm back on track with my upper enclosure mold and hopefully should be casting before x-mas, took a little longer than expected because I got sidetracked with the idea of making my own drivers, or at least part of one. Looking into making the motor for a conventional speaker is not in my means, so I'm looking into something along the lines of MBL or HEIL drivers using the motor from a cannibalized conventional driver, trying different "cone" materials over the past couple weeks I'm leaning towards the squeezebox method, but for the rest of this week it's back to the upper enclosures, just need to make the mother-mold(supporting shell) and than I can pour!!! ]]> UGP http://techtalk.parts-express.com/entry.php?205-Experiments-on-making-own-drivers http://techtalk.parts-express.com/entry.php?203-Do-Over!!!-CNCProject-xtended-Top-Enclosure-CNC Mon, 07 Nov 2011 22:03:38 GMT Okay, so I made a stupid mistake... got all the foam layers glued together and sanded down the rough edged, went to "seal it up", was going to use shellac but didn't have any so went to use some clear urethane, but of course it was out of a spray can and yes of course it attacked the foam... ruined... but now that I have the cnc process down, re-doing it is a snap, plus I thought that the shape was pretty generic anyways so thought I would update it.
So here's what the new form will look like.

plus this time I'll use a paint brush to apply the shellac;) ]]> UGP http://techtalk.parts-express.com/entry.php?203-Do-Over!!!-CNCProject-xtended-Top-Enclosure-CNC http://techtalk.parts-express.com/entry.php?201-Project-xtended-Top-Enclosure-CNC Thu, 27 Oct 2011 01:15:52 GMT Was hoping to be further along by now... actually finished by now, but It took a while to figure out the whole cnc process, I was going to update my... Was hoping to be further along by now... actually finished by now, but It took a while to figure out the whole cnc process, I was going to update my machine and ordered parts, but they where taking forever to come in and some of the parts were wrong, (in fact I'm still waiting for parts) but I got it working good enough to finally go ahead.
This is the plug for the main body of the upper enclosure. For reference the enclosures behind it have cutouts for 8" woofers(though these are not for this project) I've still got one more layer add.
Finished enclosure will have the top,bottom, and baffle of wood.








]]> UGP http://techtalk.parts-express.com/entry.php?201-Project-xtended-Top-Enclosure-CNC http://techtalk.parts-express.com/entry.php?200-Aluminum-speaker-box Sat, 15 Oct 2011 18:51:36 GMT I'm a newby, and want to install woofers in my truck. I don't have a box, but I do have an aluminum suitcase that is cool to look at and would hold my two 12" woofs. I'll cut two holes in one side for them. Is this not a good box for speakers, everything I read indicates that the box should be made of mdf, or thick plywood. ]]> bigkjh http://techtalk.parts-express.com/entry.php?200-Aluminum-speaker-box http://techtalk.parts-express.com/entry.php?198-Finishing-What-Level-of-Quality-Do-You-Have-In-Mind Sun, 18 Sep 2011 19:02:07 GMT Methods and techniques for finishing are one of the common issues discussed in the Techtalk forum. What seems like a simple issue is really quite... Methods and techniques for finishing are one of the common issues discussed in the Techtalk forum. What seems like a simple issue is really quite complicated in that there are a myriad of different approaches to achieving a "good" finish. Adding to the complexity of the issue, various successful builders have their favorite methods and will vigorously defend them should someone suggest their own personal method is "better." Notice that I've used quotation marks around good and better -- that's because therein lies the problem. Frequently, it seems, when several people are discussing finishing methods, we don't all have the same result in mind. When a particular method is labeled good, perfect, better, the best, etc. there’s a very real possibility that the person is thinking of a result quite different from what you have in mind. The result is that comparisons of one method to another are not objectively possible, because we don't know precisely what level of perfection one party or the other is referring to. With that in mind, I humbly submit the following effort to clarify what we're trying to describe when we talk about the finish we're trying to achieve, and what will likely result from a method we're recommending.

Before selecting a method, a builder should take the time to do a little thinking about what they can realistically expect to achieve. Here are several essential questions to ask yourself:

>What is my experience and skill level with finishing? If my experience is limited, do I have the necessary aptitude to learn craftsman techniques -- If you have the necessary skills, lots of options are available. Even if you don't have the skills you may still have lots of options, if have a good aptitude for learning craftsman methods, .

>Do I have the necessary tools and equipment? If you have access to spray equipment you'll have more options -- but if you don't, your options be limited to brushing, wiping, or rolling, or using spray cans.

>Are there any environmental concerns? If you’re limited to working inside your house or apartment, or there are people nearby who are sensitive to the odors that may be produced, you might be limited to water-based products. Likewise, if you’re a person with a strong commitment to environmental issues who's determined to avoid using solvent based products, you’ll likely want to use a water based finish.

>How much money can you afford to spend, or are willing to spend, in pursuit of a fine finish?

>Do you have the necessary determination and patience, as well as the willingness to devote added effort for a nicer result?

>Do you have the necessary spare time to devote to a laborious method, or do you have only a limited amount of time available to you for the project?

The continuum below is an attempt to help describe the result sought, or under discussion.

]]> Soundslike http://techtalk.parts-express.com/entry.php?198-Finishing-What-Level-of-Quality-Do-You-Have-In-Mind http://techtalk.parts-express.com/entry.php?197-upcoming-event Thu, 01 Sep 2011 02:30:40 GMT Just got tickets for this performance on October. Mariinsky Orchestra is arguably the best Russian orchestra of all times. Looking forward to it. ... Just got tickets for this performance on October.
Mariinsky Orchestra is arguably the best Russian orchestra of all times. Looking forward to it.

Mariinsky Orchestra
Valery Gergiev, Music Director and Conductor
Program
TCHAIKOVSKY Symphony No. 3, "Polish"
TCHAIKOVSKY Symphony No. 4 ]]> r-carpenter http://techtalk.parts-express.com/entry.php?197-upcoming-event http://techtalk.parts-express.com/entry.php?196-A-fancy-Xover-proto-jig Sat, 27 Aug 2011 22:42:05 GMT http://techtalk.parts-express.com/sh...ighlight=xover

Just for reference to my proto-jig for xovers.

Later,
Wolf ]]> Wolf http://techtalk.parts-express.com/entry.php?196-A-fancy-Xover-proto-jig http://techtalk.parts-express.com/entry.php?195-A-generic-2-way-Xover-layout Sat, 27 Aug 2011 22:37:10 GMT http://techtalk.parts-express.com/sh...t=Xover+layout

I thought I'd reference this in the Blog in case it was needed.

Later,
Wolf ]]> Wolf http://techtalk.parts-express.com/entry.php?195-A-generic-2-way-Xover-layout