Search This Blog

Saturday, December 29, 2012

Ethan Winer's Basic Music Theory Videos

Ethan Winer put together a new set of videos explaining basic music theory. These are geared towards the musician and audiophile. This video packs a college-level course into about 2-1/2 hours using detailed explanations and familiar musical examples. However, it includes more than just music theory, such as showing playing techniques for musical instruments, plus a segment about orchestra conductors. Because of the length the video is divided into five segments. Full information is in the description for the first video in the list. Below is the first video, and a link to all 5 videos. Excellent material as usual. Check out all of Ethan's videos for interesting and educational subjects.

Thursday, December 13, 2012

Electronics Workbench Laboatory

I don't know what took so long. Maybe building cables on the concrete floor, taking laptops apart on the kitchen granite or building a Linkwitz Transform equalizer on the coffee table. What kind of electronics fanatic does not have a decent workbench? I set about to change this situation. Most of the materials I already had in stock and were recycled from other projects. Its a mix of warped 2x4s, 4x4s, Chinese Birch, Baltic Birch, screws and PL Premium adhesive. I don't have much equipment yet, but I have the basics. A good Weller soldering iron, Fluke Multimeter, 40v 5amp variable power supply, Tektronix 2465ACT Oscilliscope. A place to put my books, a computer, ect. The backbone of my home network sits on top. A pair of 8 port gigabit switches, a TP-Link router running DD-WRT, Linksys cable modem, Silicone Dust ATSC network tuner, and a Synology 211 NAS. To the immediate right of the bench is the back of my audio rack. There is even a Kenwood 599 Amateur Radio transmitter and receiver to play with. It is a work in progress, but I'm happy I finally have a start and a place to sit down and work on things.

Sunday, September 16, 2012

Acoustic Panel Project - Absorption

Here are some simple broadband acoustic panels I made, based on the GIK 242.

The frames are made of 1" thick by 3.5" wide poplar. Poplar is used because of its resistance to warping. Finished panel size is roughly 2' x 4'. The pieces are joined with pocket screws via a Kreg jig, which by the way is a great tool to have! I didn't use any glue with these and they are super strong. The corners are simply butted together because once covered in fabric, they won't be seen. As an added touch, I chamfered the outer edge with a router. This was initially just for looks, but it also helps prevent snags when stretching the fabric over the edges. The absorption material used is 2" thick Owens Corning 703 rigid fiberglass panels, which have well known and documented acoustic properties. I then covered the panels with Guilford of Maine FR701 fabric, which is acoustically transparent and meets fire codes. The fabric is neatly stapled on the back side of the frames. The completed panel gives you 2" of absorber material with a 1.5" air gap behind it, which increases the low frequency performance and gives you a place to hang the panel onto a nail or screw. Performance wise, they should be identical to the popular GIK 242 panel as they use the same materials and specifications. I currently use 4 of these at the first reflection points of the left, center and right front speakers. 

Sunday, June 24, 2012 finally posted pictures from the past cruises
(Find me if you can!) What a great way to spend a vacation, cruising the Carribean and going to seminars with some great enthusiasts from the AVSForum and beyond. Plus you get to meet some industry leaders. (Some of which are a little snarky!) I won't be going this year, as the timing is bad for me, but i can highly recommend doing it at least once!

Tuesday, June 12, 2012

Subwoofer Location Tests

When I initially installed my Acoupower subwoofers, I placed them in the center, behind the screen and sat the center channel on the top. I knew this probably wasn't optimal for coverage of multiple seating locations, but it was a start. Having two subwoofer cabinets, at least they were mutually coupled and I would not have any phasing issues with the collocation. I decided it was time to move them around and see how the response changes. At the moment I don't have any way to separately adjust the phase or delay of the two independently so I have to strictly rely on physical placement and luck. Before making any changes, I setup my measurement system, a Windows 7 notebook computer with Room EQ Wizard software, my EMU0404 sound interface, and Nady CM100 condenser mic at the main listening position. I also turned off Audyssey MultEQ processing from the Onkyo Pro 885 and disabled the Linkwitz Transform circuit (Marchand Bassis) so I have a native raw room response. I also turned off all the active monitors, so only the subwoofer was being measured.

With the screen removed, here you can see the physical configuration of the LEFT, CENTER, RIGHT channels along with the Acoupower subwoofers in the center. As you can see, there isn't much room to jockey things around. The front wall is 12ft wide, however 2 ft of each corner starts a taper towards the wall due to triangular basstraps in each corner. The only solution was to place the LEFT and RIGHT monitors on top of the subwoofers as they were placed in the corners. This raised the tweeter level a little higher, which really isn't much of a problem, especially for my higher "second row seating".

And here is the new corner loaded configuration. The CENTER channel stand isn't the ideal stand, but it was all I had for the moment. I was also able to rotate the center vertically, keeping the tweeter height the same as the LEFT and RIGHT. I also introduced a bit of toe in on the LEFT and RIGHT channels, another listening experiment I wanted to try.

Now for the measurements...(click to enlarge)  This was taken at the MLP (main listening position) amd shows how both configurations measure without moving the microphone.

Interestingly, the response is all but identical from 15Hz to about 45Hz, with some deviation above that particularly around 90-100hz. Keep in mind, this is with absolutely no equalization at all and no smoothing of the graph. I still get the room gain down low, which works well with the sealed subwoofers and the upper end rolls off because the crossover in the Onkyo 885 is still enabled. I really should have taken multiple position measurements before I began, and again afterwards. I'm going to have to save that for next time and just use my ears for now. I am happy that there weren't any major cancellations or deep notches in the new response. This is probably due to the fact that each subwoofer is still equidistant to the mic and adjacent walls. The fact that the response changed insignificantly under 45 Hz is great news for a future modification I've been thinking of. So what did I learn here? The original center position on the subwoofers seem to be smoother around the crossover frequencies, at least in the main listening position. More tests to come, as well as more changes!

Sunday, May 27, 2012

Measuring Projector Light Output

The newer JVC projectors appear to have an issue with bulb life. Some bulbs have been known to dim and or explode after a few hundred hours. I decided to get a cheap meter ($13) to measure the light output and monitor under consistent conditions as I accumulate hours. There is a test pattern in the service menu that throws a white screen with 9 circles that I use for placement of the meter sensor. Pictured is the center circle. The average of the 9 spots are 134.8 lux with 20 hours on the lamp in normal mode. Now I have a reference which to base future measurements. Normally this is a two handed operation, but I had to hold the camera too!

Thursday, May 10, 2012

Dedicated Electrical Outlets

I finally got around to wiring some dedicated outlets above the rack. I'll now have a dedicated 120v-20a duplex outlet for rack electronics, and a 240v-20a duplex outlet for my subwoofer amplifiers - Crown CE4000s. Next up I need to recalibrate, as the amplifiers now are running with their fullest gain potential, 3600 watts into 4 ohms. each. Progress!

Thursday, April 26, 2012

Legacy Audio's Signature SE

The other day I had a chance to visit a friend and listen to his Legacy Signature SE floor standing speakers. I would not call this a review, but just sharing a bit of my experience. These particular speakers have some factory upgraded crossovers using Clarity capacitors. Having heard other Legacy speakers from the recent lines, I knew these would not disappoint. The top end driver configuration is similar to the Signature SE's big brother, The Focus SE (which a pair just happen to be in the same room) utilizing a pair of folded ribbon tweeters. A single 7" silver graphite driver for the midrange and the bottom end driven by a pair of sealed 10" drivers. These were setup as full range in a home theater configuration with 3 across the front and a pair of Legacy Phantom surrounds. A couple M&K subwoofers were also in the system, but they were turned down quite a bit. Simply level balanced with no EQ being used at all, these speakers sounded well balanced. I attribute this to the way these speakers are "voiced" from the factory. Bill Dudleston, President of Legacy, puts a lot of effort in tuning the speakers for typical room environments, so natively out of the box they can already sound good. Some minimal use of EQ should dial in the frequency response to perfection. Of particular note is the smoothness of the vocal range. Just like their big brother, they convey an effortless reproduction of vocals. Legacy has made me a fan of ribbon tweeters, which is where I suspect some of this smoothness formula comes from. The high end was perhaps a touch hot but only noticeable on a couple of recordings we heard. The bass range was well defined and tight but didn't have the same depth as the Focus SE. Any home theater system will utilize a separate subwoofer, so deep bass is a non-issue here. We rolled through a variety of SACDs and Bluray discs during the late evening. It was a pleasure to listen to about anything. I'm sure on my next visit these will be further dialed in using an Audyssey EQ system. I can't wait for that! If anyone in the South Central Pennsylvania area would like to learn more about Legacy speakers, drop me an email and I can point you in the right direction.

Friday, April 6, 2012

My visit to the Basspig's Lair!

One guy's audio system has had my attention for a number of years, His name is Mark Weiss, AKA Basspig. See his website at I've enjoyed discussions with Mark for probably over 8 years now and I've always wanted to make a trip to Connecticut to hear his audio system, but never seemed to find the time. Mark decided last month to have a get together for like minded enthusiasts called B.A.S.S. - the Basspig Audiophile Society Social. I checked my calendar and thought to myself, I'm going to go! I had an enjoyable 5 hour drive to Connecticut. I occupied my time with listening to the radio, podcasts and testing out my new dual band 2-meter/440Mhz Amateur radio.(Kenwood D710).

Upon arrival I was greeted by Mark and some other audiophiles from the Carver Audio forum. (My apologies, as I am terrible with names). After some quick introductions we got right down to business. Mark has assembled a nice basement electronics test bench and had some interesting things to show us. One of which was a multistage op-amp circuit on a breadboard which he was feeding a sine wave and measuring the distortion at the output. The coupling capacitors were of the ceramic disc type and showed moderate distortion via a spectrum analyzer, yet a fairly healthy looking sine wave on an oscilloscope. Swapping in some polypropylene capacitors dropped the distortion to almost undetectable levels! He has a nice YouTube video of this demonstration which you can view HERE. We also saw several SET tube amplifier demos and Mark demonstrated his newly acquired Tektronix Curve Tracer. This device shows how a tube operates dynamically throughout a range of stepped grid voltages and shows the voltage-current relationships, ect. It also works well for semiconductors such as transistors and diodes to give a complete picture of the devices characteristics.

While all the electronic demos were fun what I was really here for was to hear Mark's sound system. Designed, assembled & upgraded for decades, by the Basspig himself. Upon entering the room that I've look at countless times in the Internet, I immediately noticed one thing. His basement theater & studio looked small. Things really do look bigger on TV! After a brief overview of his rack equipment we sat down to enjoy some AV bliss. First up was some video Mark shot downtown to demonstrate that the differences between 480p and 1080p video are not also so apparent. While the 480p looked good (probably due to the high quality signal chain Mark uses) the jaggies and aliasing were quite evident. The 1080p video had little, but some observed artifacts. At some point Kal Rubinson, a contributing editor at Stereophile magazine stopped in to join the party. We then watched some NICE sharp video Mark shot of some his wife, Mary Ann's Geisha doll collection. The close up textures of the doll's clothes were very detailed and the smoothness of the porcelin faces looked flawless. A sample can be viewed HERE. Onward to some of Mark's recordings of Saint-saĆ«ns Cello Concerto he shot in Boston. What can I say, when a recording has such superb video and sound you tend to get lost in the content. Mesmerized by the beautiful soloist everyone was amazed by her talent and the punishment her cello was put through. All this with rather mild volume levels, was quite enjoyable. Sometime during the presentation, Ethan Winer (Owner of RealTraps) and his wife Elli joined us. His new book, The Audio Expert, will be released in about 2 weeks, and there are reference's to Mark's system in the book, so look for it on Amazon.

The next demo was Mark's near field recordings of a Zambelli fireworks show. This is the closest reproduction I've experienced compared to the real thing. It might even have been better! The dynamic range had a wide aperture (>85db) From the crickets in the field and the children's laughter in the distance to the 8" shells popping overhead so tight and defined without a hint of straining. One guest had to hold on to his hat because it was literally trying to dislodge itself from his head! The transients were that strong. This sound system is akin to a giant lung, pulsing air very quickly to reproduce the explosions being shown in full HD video which by the way was equally as beautiful, showcasing his DLP projector's contrast ratio to display the dark sky and flashes of color from the explosions. A sample compilation can be seen HERE, but I assure you it won't be the same experience as the uncompressed Bluray via the Basspig's rig! After a few more electronics lab experiments we convened in the kitchen for some of Mark's now famous artisan cheese lasagna and a little wine. Some of the neighbors were setting off firecrackers in response to our playback session, apparently thinking we were doing the same!  After some friendly group conversation over a great meal, I ended up as Mark's last guest. We returned downstairs where we reviewed some things in his lab and moved on to some more audio demos.

Mark demonstrated Carver's sonic holography, a feature of the Carver C-4000 preamp. Using only 2 channels it really does put images WAY out to the left and right. I had to verify the material really was 2 channel and that his side surrounds were indeed off. It was very convincing, but limited to about a 2 1/2 ft wide sweet spot. If one moves to the left or right too far, the illusion disappears. We also played around with a subharmonic synthesizer, which can restore some of the fundamentals in poorly recorded music. I have one in my rack as well, but I have not really used it. I wish i could have had more time to demo some things I brought with me, but Mark kept pulling out some great material and I was more than happy to absorb the experience.

Next Mark really put the pedal to the metal and turned the volume up to Basspig levels. Its a shame everyone else didn't get to experience this elevated level. I can't remember the exact songs he played. It could have been the pop Asian songs from his vast collection or the Isley Brother's remake of Summer Breeze. But the pressurization of the room was unbelievable! Any article of clothing that is the tiniest bit loose was subject to the undulation by the low frequency wavefront. To my surprise this even included my scalp, as it seemingly floated on the top of my skull, moved by my hair as it became an acoustic sail captured in the massive invisible tide of infrasonics. I know, it's a mouthful of to read but it's difficult to capture the experience in words. Yet despite all this high SPL, the sound is not fatiguing and doesn't make one wince in pain. This my friends is the hallmark of a sound system with LOTS of overhead and very low distortion.

We played around with some MIDI stuff later on, which I only really have a concept of. By now it was getting late so we decided to break for some coffee, which I had roasted the day before and some home made rum cake which I brought along. After more great conversation, it was almost 1am and I had a long 5 hour drive home. I could have spent days on end talking to Mark about audio, electronics, politics, birds, ect. He's a good guy and has a tolerant wife to put up with his audio "machine" downstairs. After 24hrs, 500+ miles and probably 140dB, I was very glad to be home in my bed!

Friday, March 23, 2012

Popcorn Hour A-300 has arrived

I just received a Popcorn Hour A-300 streamer to try in the home theater. From Hong Kong to Pennsylvania in 3.5 days. DHL was moving! The primary use will be to stream Bluray .ISO files via HDMI with full HD sound pass thru. I will also use it for streaming multichannel FLAC files from a server. This little box is all metal and appears well built. One thing I did discover that is a little discouraging is that at idle the A-300 consumes about 8 watts. Powered off or standby, it also consumes 8 watts! It is astounding that in this day and age some engineers think kilowatt hours grow on trees. I still have lots of testing and setup before I put the A-300 in the theater but for the most part I like what I see.

Monday, March 19, 2012

Subwoofer Ports

Subwoofer Ports

Great explanation of how speaker ports work, taken from the link above.

"The resonance of a vented box is caused by two factors. The first factor is that air in an enclosed space behaves like a spring. Anyone who has played with a beach ball, sat on an air mattress, or pressed on a balloon will realize that after pressing against an air-filled object, the object will spring back to its original shape. Ultimately, the air molecules want to remain a certain distance apart, and when you temporarily squeeze them together, or pull them apart, they will quickly return to their preferred spacing. The air inside a vented enclosure behaves similarly to you sitting on an air mattress; it acts as a spring pressing against the driver's cone, and also pressing against the air in the loudspeaker port.
The loudspeaker driver exerts force on one end of the spring, and the spring in turn exerts force on the air in the port, which brings us to our second factor that sets the resonance of a vented box. The port air is confined by the port walls and moves primarily as one big "slug" of air. This volume of air moves in and out of the port as it is pushed and pulled upon by the spring. The larger the volume of air in the port, the heavier it is. A heavy slug of air changes direction more slowly, from moving into the box to moving out of the box, when the spring pushes on it. A lighter slug of air can change direction more quickly.
Combining the two factors above sets the resonance of a vented enclosure to a specific frequency called the box resonance frequency, commonly abbreviated Fb. The box resonance frequency is defined by the combination of the volume of air in the port and the springiness of the air in the box. A large enclosure volume makes for a soft spring, and a small enclosure volume makes for a stiff spring. We use a large box (i.e. a soft spring) with a heavy (i.e. large volume) slug of port air to produce a low Fb. Virtually any box resonance frequency can be chosen by careful selection of port volume and enclosure volume."

Thursday, March 15, 2012

New projector for the system

I picked up a new projector. A JVC RS40, B-stock from AVScience store for $1779. This is going to be a huge improvement! JVC's LcoS implementation (D-ILA) operates much like a 3-chip DLP only instead of mirrors it uses liquid crystals over a mirror substrate. A great explaination of LcoS is HERE.

Friday, February 10, 2012

My Front Soundstage

Test 1st Post

Mackie HRS824,626 active studio monitors and DIY 18" Acoupower sealed subwoofers in custom Birch/Poplar enclosures.