Saturday, June 27, 2009
Testing Loudspeakers- Joseph D'Appolito - still considered a standard reference book with regards to the practice of testing loudspeakers to get their basic parameters.
Loudspeaker Design Cookbook - Vance Dickason - a good reference guide for those new to loudspeaker design - it provides basic info regarding all the major steps in a build, and you can google your way thru more details on any of these topics.
So, I will purchase those 2 if/when I get the measurement jigs/mic/software all working to my satisfaction.
Google Sketchup - http://sketchup.google.com/index.html - a free, intuitive program to draw 3D images of your project.
Unit Converter - http://joshmadison.com/article/convert-for-windows/ - a free program to convert between different units of measurement - great for metric to english unit conversion
GIMP for Windows - http://gimp-win.sourceforge.net/stable.html - a free photo editing tool, similar to Photoshop but without cost
FSCapture - http://www.portablefreeware.com/download.php?id=775 - a fantastic freeware image capture tool - useful for making your screenshots, whether you put the screenshots into a document or post them on the internet - hopefully you are creating a word document for your project, with notes, drawings, etc???? Even better, a file folder to store your different files in for future reference.
OpenOffice - http://www.openoffice.org/ - a free office suite, with capabilities similar to Microsoft Office. Useful for creating documents and PDF files, and the spreadsheet program can assist in automating some of those math equations you might use whilst designing your speaker, and the drawing program can assist you in diagrams, crossover design, etc....
Audacity - http://audacity.sourceforge.net/ - a free replacement for the Windows Sound Recorder - again, useful for recording and analyzing sounds
DPC Latency Checker - http://www.thesycon.de/deu/latency_check.shtml - a program to check your audio hardware for latency - latency is bad when it comes to speaker measurement software
CutList Plus - http://cutlistplus.com/ - a commercial (pay) program that will allow you to layout all of your cuts before you pull out your saw. This should save quite a bit of time, as you simply need to pull out the board, lay down the cuts based on the sheet, and go to town with minimal waste and no lost time planning your cuts in advance - I ain't gonna buy this until I have successfully created my first 2-way speakers and I am satisfied.
Friday, June 26, 2009
I purchased an Expresscard SoundBlaster X-FI from Dell, for $82 incl Tax S&H. Hopefully it is a good compromise - enough quality to perform measurements, no lag or latency issues since it is plugged into a slot, not a USB/Firewire port, and less than $100.
The next purchase was $79 at Mouser. This covered 2 generic plastic boxes for creating the ARTA and LspCAD jigs, one Hammond enclsure for the Wallin preamp, and some resistors, capacitors, diodes, chassis mount banana jacks and rca jacks, and whatnot to round out the inventory I already possess.
Of course, I can't test without speakers to test with. $60 to Parts Express ($16 for S&H - yikes!) to purchase 2 Goldwood 1" Tiatnium tweeters, 2 generic 6" woofers, and 50' of 16ga speaker cable. If I get impedence and FR measurements, then I will get some xover parts for testing, and find someone to assist me in making 2 test boxes.
Over $220 just to test out a hobby. Once I build the jigs and Wallin, I will post pictures. Friggin expensive test, hope that the equipment all works. To be honest, it doesn't seem like some resistor jigs and a homemade mic & preamp will work for squat, but you never know till you try.
Thursday, June 25, 2009
Part of my choice for LspCAD and ARTA is that I can create some semi-inexpensive jigs, and actually use the 2 programs to measure speakers.
If it doesn't work, I don't loose a huge amount of cash. If it works, then I keep using the same equipment and software.
I would like to run the tests outdoors, in an empty field, so I don't have to worry about echo and room response, etc... Based on that hope, I plan on the following rig:
Dell Vostro 1510 Laptop, Vista 32bit, 4gb RAM, Dual-Core CPU (already own it)
Soundblaster X-Fi Expresscard (gotta buy)
JBL GTO Amp - I have a car stereo amp in my truck, powering 2 coaxials and a 10" woofer. I have easy access to the amp, so I can use it for testing.
There are a few items I will have to solder together also...
ARTA Jig - http://www.fesb.hr/~mateljan/arta/AppNotes/AP1_MeasuringBox-Rev4Eng.pdf - looks like $20 in parts to make a jig for measurements.
LspCAD Jig - http://www.ijdata.com/justMLS%20manual.pdf - another $20 to create a box with resistors to measure loudspeakers with LspCAD.
Wallin Preamp2 & Panasonic WM-61a Microphone - http://mysite.verizon.net/tammie_eric/audio/preamp2/preamp2.html
I have 80% of the parts already for a Wallin Preamp, and I bought 3 of the circuit boards in 99/00 when they were being made (a buddy wanted a portable powered Mic for less than $50, this was it) back in the day. If this works out, I will get the mic calibrated - if not, not a huge loss.
Looks like the total outlay for the SB card will be $100, and the 2 jigs / PreAmp / Mic will be $85, so that is $185 just to test a hobby out... wonder if I should do it or not?
However, it seems like a lot of education and real world experience are required if you decide to skip the computer. I ain't got that going for me.....
So it looks like some software will help a lot... I was initially very excited to learn about Speaker Workshop (http://www.audua.com/), but there are a LOT of people who express frustration getting it to work in a repeatable manner. I think that free software is awsome, but not if it causes me to loose any of my limited hair supply :)
So, I started hunting for software. Ideally, I would like to spend as little as possible for a program that will assist in both the speaker measurement, crossover design, and box design subroutines. I also want to demo the product first, if possible. There are several packages available, but I have narrowed my choices down to ...
LspCAD - http://www.ijdata.com/
SoundEasy - http://www.interdomain.net.au/~bodzio/
ARTA - http://www.fesb.hr/~mateljan/arta/links.htm
Praxis - http://www.libinst.com/
Further review and research (i.e. googling) has caused me to steer towards LspCAD - the standard edition can do the basics, including some nifty crossover stuff... however, it looks like ARTA may perform the measurements a bit better..... sigh... If LspCAD can't do the measurements well, then its $200 for LspCAD Standard and upwards of $100-$120 for ARTA - that is a lot of bread.
Both LspCAD and ARTA have demo software available, so I have downloaded both packages.
My goal is to make 2 sets of speakers. First one is a set built from very inexpensive drivers, both as a learning experience and as a pair of speakers for my mother to use.
The next step will hopefully be quality drivers for a home theater setup that will sound as good as the stuff costing thousands, but with the satisfaction of building them myself.
The hard part will be the cabinets - I don't currently own a single woodworking tool, so we shall see if I can find other kind souls to assist me as time progresses. I am a condo dweller, so I can't just drop $$ on woodworking equipment (no garage).
My current skill levels:
Computers - super advanced Cisco/Microsoft/Linux professional
Electrical - novice
Woodworking - zero