Optoma UHD65 4k Projector Added

I’m enjoying revisiting my Blu-ray collection since I’ve installed this $1500 factory refurbished Optoma UHD65 HDR 4k projector. I’m finding that the upscaled 1080p video has taken on a newfound amount of sharpness and detail. Even though it uses a native 2716x1528 DLP imager chip, its pixel shifter allows a full 3820x2160 (8.3 million) discrete, addressable pixels on the screen for a very affordable price. The downside to pixel shifting projectors is the pixels overlap a bit compared to a native 4k imager chip projector. Still the picture is stunning compared to a HD 1920x1080 projector. To me, the Achilles heel of the projector is the amount of noise it makes. It can be distracting during quiet scenes. I must have been spoiled by the low noise of my JVC RS40 but at this price point I can live with it. I would also say the black level isn’t super deep, but adequate considering how bright this projector is. Overall it puts me one step closer to my goal of having the best seat at a live concert and a welcome improvement in picture quality over my JVC. Sorry no screenshots, I only have a smartphone camera and its difficult to get exposure and resolution to represent what I see in person!

Carver C-9 Sonic Hologram Generator

I just installed an interesting piece of gear into the signal processing rack of my sound system, a Carver C-9 Sonic Hologram Generator. Designed by Bob Carver in the 80's, his Sonic Hologram Generator has been a feature in various Carver preamps at the time. The C-9 is a stand alone unit that some have called his finest implementation of the technology. I've wanted to tinker with Sonic Holography in my own system ever since it was demonstrated to me by a friend, Mark "Basspig" Weiss in his incredible sound system. 

The problem it attempts to solve is called acoustical crosstalk. What's that? For example the sound from your LEFT speaker is heard by your LEFT ear. Inevitably some of this sound is also heard by your RIGHT ear slightly delayed, otherwise known as acoustical crosstalk. This can cause some anomalies in our perception of the sound. Headphone aficionados don't experience this crosstalk at all as you can imagine, which is one of the reasons people love the sound of headphones.

So what does this thing do?

It's basic function is to take a 2-channel audio recording and attempt to eliminate acoustical crosstalk between the speakers and your ears. The Sonic Hologram Generator does this by sending an inverted copy of the audio signal to the opposing speaker with amplitude and delay such that it actively cancels the crosstalk at your ear. This can create a similar effect to using headphones, only instead of the sound appearing only inside your head as headphones do, the sound can appear in front of you anywhere in a 180 degree hemisphere. When implemented correctly, it sounds incredible. For a very detailed explanation you can read about it in the patent here. Simplified in the diagram below the Lr and Rl paths get nulled out by producing an inverted signal from the opposing speaker mixed in with the wanted direct sound paths Ll and Rr.

This all sounds interesting but there are a few downsides to be aware of. 

1. It's very dependent on the program material chosen. Not all music lends itself to the effect. 

2. Some rooms it just doesn't work well in. Speaker placement and listening position is critical. See the manual for more information. 

3. You must be in the "sweet spot" to hear the effect. If you move about 18" in either direction the effect goes away. This can be adjusted by a small amount with the Listening Aperture button. 

Despite these shortcomings I look forward to playing around with the C-9 with my 2-channel recordings. You can find the C-9 on EBay for $100 or less most of the time, which is where I bought mine. Upon receiving I opened its up to examine the inside and it looked really clean and in good condition. The power supply electrolytic capacitors showed no signs of distress and the rest of the caps are green polyester film types. I did clean the switches and RCA connectors with Deoxit D5 while it was apart. You can install this in series with any music source like a CD player or if your processor has an external tape loop connection you can use that. There are 2 sets of RCA connectors on the rear, in and out for the left and right. The unit itself has no power on/off button, but it does have a bypass/engage switch. I might add a power switch to the front panel in the future. There are also some other switches for varying parameters to a degree. Listening Aperture can be set to narrow or wide and Injection Ratio can be set to normal or theoretical. This is the amount of crosstalk correction applied. Also note that you may use this device to encode the Sonic Holography signals into a recording itself for playback on a system without the hardware.

While I find discrete multichannel audio greatly enjoyable to listen to, the selection is limited. There are a lot more 2-channel recordings in the world to hear. Sure we have Dolby PL2x and DTS's Neo:6 and many other processing modes that create multichannel surround from a 2-channel source but properly dialed in stereo sounds good too. Add in a Sonic Hologram Generator and if your setup is just right you will swear there are speakers in places none exist. That's magical! 

Panel Bracing the Main Cabinets

Here you can see this loudspeaker cabinet has the internal bracing in place just prior to glue up. You'll notice I'm using pocket screws. Pocket screws are an easy way to firmly hold the bracing in place while glue is drying therefore no clamps are needed. I decided to use panel bracing along with a cross brace which anchors the baffle between the woofer and the waveguide cutout.

The "glue" I'm using is called PL Premium. Its a polyurethane construction adhesive commonly found in home improvement stores, or here on Amazon. It expands as it cures which helps fill in gaps, unlike your typical wood glue which shrinks. Its very messy to work with however, so wear nitrile gloves and be careful. It has the consistency of peanut butter and sticks to whatever it touches. Once you get it on a surface, its very hard to remove.

Panel bracing is a bracing scheme which increases the resonant frequency of a panel by physically subdividing it so acoustically it appears as several smaller panels. Panels tend to vibrate at a frequency determined by a formula which takes in consideration the dimensions of the panel as well as its density, bending stiffness and a few constants.

Our goal is to attenuate these resonances enough that they won't color the sound of the loudspeaker's output. We do this by first pushing the panel's resonance frequencies up and out of the band used by the woofer by altering the panels apparent dimensions via bracing.  Second we then attenuate those resonances with mass and stiffness. One could write a book on this topic alone. I've studied cabinet construction of JBL's 4xxx line of classic studio monitors and note they have done a great deal of research in this department. Not trying to reinvent the wheel, I've chosen this tried and true method to quiet these enclosures, plus a few other considerations not seen here to add a degree of overkill.

If you're interested in pocket screws, I started out with this kit Kreg K4MS Jig Master System with Pocket Hole Screw Joinery Kit. If you're a DIY type, you'll be amazed how many uses you'll find for pocket screws!

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Speaker Upgrade Project Begins

This will be the first post about my new speaker project. I saved up enough money to purchase pretty much any high performance speaker system I wanted, however after much research and debate I decided to build my own. I could not turn down the opportunity to learn new things and use my skills to fabricate something with my own two hands. I'm going to divide the project into 4 distinct phases.

Phase I - The Left, Center, Right top cabinets. Top I define as the tweeter and midrange cabinet. These cabinets will be of high sensitivity and cover roughly 80hz to 20Khz without use of a Helmholtz resonator.

Phase II - The midbass system. This system will relieve the tops from somehwhere around 120-200Hz on down to about 40Hz. Final crossovers will be determined during implementation.

Phase III - Surrounds. Timber matched as close as possible to the tops, using the same tweeter. I place lowest priority on the surrounds and may actually complete the subsystem before surrounds?

Phase IV - Subwoofer system. As potent as the dual Acoupower 18" system is, at this point it will be the weak link and will be upgraded with a system capable of more air displacement for the lowest octaves.

My primary focus on this upgrade will be on the left and right channels. The midbass system will ONLY apply to the left and right. The center "top" will be identical to the left and right and extend to 80Hz only, which will satisfy movie playback to the THX standard. Center channel information below 80Hz will be routed to the left and right channels. The system will be modular in nature and a a versatile as I can make it. As Steve Guttenburg recently stated, something like 99% of all the recordings out there are 2 channel. I want to do that REALLY well and the rest is a bonus. I hope you follow my journey!

Audio & Video System Expectations

It's been quite some time since I've written to the blog. This year summer & fall had a way of running amok due to household projects, yard work, working overtime at my job, ect. While I may not had had time to spend working or enjoying my entertainment system as much as I'd like, my mind is still abuzz with where it's going with respects to future upgrades and it's direction. Having said that today I'll write a little about my system expectations.

Most audio enthusiasts are typically in one of two camps. The 2-channel music lover and the multichannel channel movie lover. A lot of folks aim for the best of both worlds, which is sometimes a compromise and sometimes very successful. Myself, I am a music fan. I have somewhat different goals than a movie fan might have. I always hesitate to call my room a "Home Theater". Actually I think the moniker is a complete misnomer. "Home Cinema" is a much more accurate description. Still I prefer to think of my room as a media room or entertainment center. Most movies I'll watch once or twice, but a good concert is enjoyed over and over again. Bluray delivers that experience with a high quality lossless multichannel sound track and 1080p picture, so it's suited for both movies and music playback. Bluray is my format of choice - but times are changing!

My video system was built with a 2.05:1 constant image area screen utilizing the maximum height I felt comfortable with. This means 16:9 video is shown as large as practically possible in my room, yet I also get to horizontally expand the picture to a wider CinemaScope 2.35:1 in order to maximize a movie if desired. Since most concert footage is 16:9 format, I've got the biggest picture for that application and still a really wide screen for the occasional movie flick. The traditional downside to a constant image area screen is that you have black bars on the horizontal or vertical image edges depending on which ratio video you are projecting. I've thought about implementing  some manual masking in the future, but the superb black levels of the JVC D-ILA technology in the RS40 projector make for black bars that are very undestracting. For now I'm pretty happy the way it is. I'm already thinking about the next generation DIY screen, so this might be it for the time being.

Now let's talk about the audio side. I've come to the conclusion that my ideal audio system must be capable of two different modes of operation. 

First and most important is the exact reproduction of what is recorded on the source material. This is typically everyone's goal. Flat frequency response, low distortion, good behavior in the time domain, ect. While these are respectable goals, they can fall short in the entertainment factor. Let me explain. Not all recordings are high quality and when faithfully reproduced can sound quite hideous. Such recordings that come to mind are mass produced rock music from the 80's and 90's, most streaming services, poorly digitized lossy MP3s and other bandwidth limited distribution methods such as Sirus/XM. Satellite radio music is so poor and compressed they it is often unlistenable even in my car! Fact is there are more recordings I'm interested in that cannot be sourced in high fidelity or high definition.  I won't NOT watch or listen to something I'm interested in, so what can I do about this?

The second goal of my ideal audio system is to modify the signal in an attempt to add back some of the lost pizzaz. One can alter the frequency response via equalization, add back in lost fundamentals with a subharmonic synthesizer, restore dynamics with range expanders, ect. The purist audiophile will poo-poo at this but if it's not enjoyable, what's the point? I'd much rather be absorbed into an enhanced performance than being distracted by a lousy faithful reproduction. The problem lies in the fact that it's not the media type that defines audio quality, but the work that goes into putting it there isn't always done with the best efforts. Even modern media can be poorly mixed or mastered. Streaming however is slowly catching up in quality and has an exciting future, with services like Netflix, Quello and YouTube. Yes I said YouTube! There are more and more high quality 1080p videos with well recorded sound out there. There are even a few 4K videos posted for those of us with capable displays. There are also products from companies like Darbee Visual Presence that are able to enhance video in ways that don't subtract details or add artifacts to the picture while increasing the viewing pleasure. 

My next few posts will be about my next level of system upgrades which support these ideas.

I'll end this post with a 720p YouTube video that has well recorded sound. This is Tool's 46 and 2 performed by the students of Aaron Okeefe's Music Instruction at The Tracking Room studio in Nashville, TN. It gives me goosebumps to see these talented young kids nail down this song!

My Current System

** This page is a work in progress. I'll try to keep this up to date and linked on the homepage.**

Last Updated 3.28.13

My entertainment area occupies half the basement in my 1978 built home. The room is approx 12' wide by 45' deep with 7' ceilings. I wish it was wider and had more height, but its what I have to work with! I do plan on making changes to the walls and ceiling, so expect some updates. Front row seating is a 3-seat sofa with reclining ends. The front row is about 14' from the screen. Behind the sofa is a 6' wide DIY bar where there are 2 more seats. A DIY in-wall 19" equipment rack is to the left of the bar. Some DIY acoustic panels help with first reflection points. Most of my viewing is high definition Bluray concerts. I'm a music lover first and foremost. If I do watch a movie, it has to be a blockbuster. For this reason I hesitate to use the term "home theater". You'll notice that most of my upgrades from here on out will be geared as such. As you can see my decision to NOT go with a popular 2.35:1 Cinemascope screen, take my viewing habits into consideration.  

View from behind the bar (2nd row seating)

Behind the screen

10' x 5'  2.05:1 ratio CIA borderless AT screen

DIY 19" In-wall rack

Onkyo PR-SC885 Preamp & Processor. Handles all inputs from various sources, processes the audio streams and applies equalization based on the Audyssey XT room correction algorithms & measurements.

JVC RS40 Projector. A reference class 1080p 3D projector using D-ILA, or JVC's version of LCoS technology to produce an image with a high contrast ratio. I'm using a Chief mount, which after my previous DIY mounts, I HIGHLY recommend spending a little extra for a nice mount such as this.

Oppo 93 Bluray/SACD/Network Streamer with v1219 firmware. This is primarily my Bluray disc player. It is also an excellent network streamer for FLAC, MKVs, MP3s, ect. The firmware version I have installed still allowes playback of Bluray .ISO images, but only from a locally connected hard drive.

Popcorn Hour A-300 A low powered network media jukebox (NMJ) with the capability to play many media types, including Bluray .ISO images over a network drive, with full HDMI outputs bitstreaming HD audio codecs.

Seymor A/V Centerstage XD - Acoustically transparent screen material was used to construct a large screen of 10' wide by 5' tall. These screen dimensions give me the most bang for the buck on the 12'x7' wall. The ratio is considered a CIA, or constant image area screen and the ratio is 2.05:1. The concept was conveyed to me by  Anthony Grimani of PMI Ltd. while he lectured the Home Theater Cruise in 2009. I get maximum height while watching 16:9 ratio concerts, and maximum width while watching 2.35:1 cinemascope movies and can accomodate any ratio in between. The downside is the need for masking every ratio, which in reality is minimized by using a high contrast ratio projector. Not convinced? Click HERE. I made the screen frame from poplar wood and it is borderless. It floats from the joists above in front of the speakers. The fabric was stapled and placed on a bias to minimize moire patterns.

  

Marchand Bassis. A dual analog Linkwitz Transform circuit. Shapes the subwoofer output signal to counter the natural rolloff which occurs when using a non-ported (sealed) subwoofer design. It can be tailored specifically to match any sealed subwoofer design parameters to a given room's gain structure. I bought this as a kit, assembled and tested myself.

Crown CE4000 rack mounted amplifiers. Found at bargain prices on the used market, this model amp was the test bed for the future flagship I-Tech line of amps using an advanced derivative Class D architecture (which Crown calls Class I). Coupled with a power factor correcting switching power supply produces an extremely efficient amplifier. Powered with 240vac it draws very little current yet produces up to 3600 watts RMS bridged into a 4 ohm load. I use a pair of these on 240vac mains to drive a pair of sealed subwoofers. I also have replaced the internal cooling fans with Scythe S-Flex SFF-21D low noise fans for near non-existent noise levels.

Mackie HR series studio monitors. Models 824 (LEFT and RIGHT), 626 (CENTER) and 624 (SURROUNDS) Active studio monitors using a servo controlled midrange augmented by a passive radiator and a 1" dome tweeter on a mild waveguide. 

Acoupower Subwoofer System.  A DIY subwoofer system I created using a pair of Acoupower 18" drivers in sealed, down firing plywood cylinders. More information soon.

Acoupower Sealed Subwoofer Cabinets

Acoupower 18" Studio Driver

Furman PF-Pro R Surge protection and conditioning for all rack electronics (except subwoofer amplifiers)

Synology DS211 NAS  Raid file server 2x2TB soon to be upgraded with a larger Synology.

MISC EQUIPMENT :

• Assorted APC Battery backups
• Behringer Feedback Destroyer Pro - NOT IN USE
• Behringer Ultra Bass Subharmonic Synthesizer - NOT IN USE
• Quadcore PC

Acoupower Subwoofer Drivers

I compiled some videos about the subwoofer drivers in my audio system. It is an introduction and comprehensive look at the metal and soft parts which make up an Acoupower driver. You may have seen the introduction posted here before, but this includes videos of the inside of the drivers. A full 20 minutes worth. I'll soon publish a post showing the buildup of my cabinets and other data.

A quick summary of specs on these amazing 18" drivers :

- 6" copper 2 layer voice coil in an underhung configuration.
- Largest neodymium magnet used in any loudspeaker
- 97% of magnetic field lines in the gap
- Entrainment techniques used to eject hot air from the motor
- 5 sqft. of heatsink surrounding the motor
- 18mm of one way throw and still at 100% linearity on the BL curve.
- 39mm of one way peak throw
- 1% odd order distortion with 1KW input power

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.

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. 

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!

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!

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!

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.

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.

My Front Soundstage

Test 1st Post

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