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Monday, September 4, 2017

DIY Network Rack

My network gear has growing like a travelling watermelon vine, so I decided its time to consolidate everything into some sort of 19" rack. A friend gave me a pair of rack rails a few months ago and I set about figuring out how I was going to implement them. After some research and thought, I found a simple design using 2x4s connected with pocket screws to frame out the rails from a fellow blogger which can be found here Tom Builds Stuff - DIY Server Rack Plans.

I've always been pleased with pocket hole joinery via my Kreg Jig. For this build I wanted to go heavy duty and used a Kreg KJHD jig with their Heavy Duty pocket screws. Kreg's KJHD line is for use in 2x4, 2x6, etc lumber. The screws as you can see are heavier and are come with an anti-corrosion coating with for outdoor use. As usual, the whole process of doing pocket joints is a pleasure.

Most of my lumber I already had sitting around. Several pieces I had were from old skids that were full of staples that I was going to burn, so I pulled them out of my recycle pile, removed the staples and cut off the bad parts. The wheels are 3" polyurethane with both wheel lock and caster lock cost about $7.50 per wheel. I liked them better than the wheels at Harbor Freight and they were only about $7.50 per wheel. You can find them HERE on Amazon. My rack won't see much rolling, but I wanted to be able to easily swing the rack around to access the back.

I was going to make a plywood top and bottom, however I had those recycled 2x4 scraps laying around to put to use and the whole open space concept for airflow was appealing to me. I placed the 2x4s across the width on the bottom because I knew I'd have a long UPS and a PC needing depth support. The top I figured I might have a monitor and keyboard for server access, so I placed 2x4's across front to back to support wide items.

Here you can see my initial setup of the rack in my basement, next to a workbench and the rear of my in wall audio rack. With all 4 wheels locked, I was relieved that the rack is pretty solid. This was a concern, as I wanted to keep the NAS as stable as possible. Theres still some cleanup to do, but its up and running. Best of all, there is no glue in the rack and I'm free to break down the entire thing and reuse any of it at anytime I want, or add to it in any way I see fit. Versatility is the name of the game when you build it yourself.

Below is a list of some of the gear currently in the rack, with links.

Ubiquiti US-24 port Unifi Switch
Ubiquiti Unifi Security Gateway (router)
Ubiquiti Unifi Cloudy Key
Ubiquiti Networks Unifi 802.11ac Dual-Radio PRO Access Point (not pictured)
Motorola SB6141 Cable Modem
Synology DS1817+ 8GB NAS - loaded with 5 HGST 8TB NAS drives in a RAID6 array and 2 Samsung 2TB Spinpoint drives in a RAID0 array.
Synology DS211 - backup target 2 Seagate 4TB drives in a RAID0 array.
Western Digital MyBook 4TB USB3 - backup target
SiliconeDust HDHomeRun Extend - Over the air networked HD broadcast tuner (new version)
APC SUA1000XL Battery Backup - Extended Runtime battery backup.
Dell Studio XPS9000 - Core i7 4GB - Sitting idle for future use.

Tuesday, February 28, 2017

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! 

Saturday, February 18, 2017

Newest Acquisition : A Commodore 64 Computer

On the bench today is a blast from my past. A clean Commodore 64 computer and Commodore 1702 monitor I just bought. I spent many nights pounding away at the keyboard on a computer exactly like this in my teen years, along with a dedicated tribe of friends many of whom still have their C64 computers. Despite how advanced emulators are today, there's nothing like having original 8-bit hardware running right in front of you.

I popped the top to have a look at the motherboard and everything looks to be in good condition. No bad capacitors or evidence of past repairs or disasters. It's a Version A Rev B motherboard made in Hong Kong in 1984 which makes it a very common board. It has the 8-pin video connector which offers separate chroma and luma signals to present the monitor with a very clear 320x200 NTSC picture. The sound chip (SID 6581) is also socketed in this version. I'm not going to get too geeky about it, as I just wanted to have a nice usable machine to have fun with. I have a stack of 5 1/4" floppy discs I saved from all those years ago with personal data and programs. I'll probably get a few extras along the way like an SD card based drive emulator, a real 1541 5 1/4" disk drive and perhaps a PC interface for the drive as well. 

These specs look really silly compared to modern day computers, but 35 years ago it was awesome to have such hardware in your home. Clever programmers optimized their code to make the most out of the hardware. Sloppy programming wasn't allowed and RAM wasn't cheap or in abundance like it is today.

Data Sheet

  CPU         : 6510 @ 0.9852484444MHz [1] (PAL)
                       1.0227277143MHz [1] (NTSC)
  RAM         : 64kB DRAM
                .5kB SRAM (color RAM $d800-dbff)
  ROM         : 20kB ROM total, consisting of three ROMs
                (BASIC and Kernal share one ROM on new boards):
                  - 8k BASIC V2      ($a000-bfff)
              - 8k Kernal        ($e000-ffff)
              - 4k character ROM ($d000-dfff)
  Graphics    : VIC-II ($d000-d3ff)
  Sound       : SID ($d400-d7ff)
  Int. drives : -
  Interfaces  : 2 x control port (CIA #1 ($dc00-dcff)),
               cassette port (CIA #1)
                  expansion port,
                  serial IEC (CIA #2 ($dd00-ddff)),
                user port (CIA #2)
  Keyboard    : 66 keys, controlled by CIA #1
  Power supply: external transformer (9VAC + 5V DC)
  Extras      : We don't need no frills ;-)

Tuesday, January 24, 2017

Saving Caulk Tubes

I've grown tired of ruined tubes of open caulk. For years I've just stuffed a nail or screw into the nozzle and hoped for the best. Looking over possible solutions I decided to give these red caps a try. They are essentially like a little condom that rolls down over the end of the nozzle providing an air tight seal. So far they seem to be working fine. They are semi-reusable. I had one with a little hardened product in the end that I had to toss, but otherwise I've had no issues with these, even with my favorite "glue", polyurethane adhesive. I am reading that if you use this in addition to a nail or screw shoved down into the end, the results are even better. If they save even one tube of caulk they are paid for! Do you have another favorite way to save opened caulk tubes? I'd love to hear your methods.

Friday, January 6, 2017

Weather Underground : The Best Weather App & Website

The weather affects everyone's lives daily, so it's important to pay attention to accurate forecasts to make the best use of your time. I used to rely on the Weather Channel's website and iPhone app. The Weather Channel has to be the best, right? Well last year sometime they redesigned their website and app to my dislike, and it forced me to look for viable alternatives. Let me tell you I'm so glad they botched their update, because I found something I liked much better - Weather Underground. I'm going to give a quick and dirty run down of why I like it so much.

As soon as the app loads, it uses your GPS location and searches for the nearest weather station. You get current weather data from the nearest source, not from the airport on the other side of the county, or the top of the hospital downtown. Some data does come from the National Weather Service (NWS), but local data mostly comes from a PWS - Personal Weather Station. Its great to see a crowd sourced community of 100,000 personal weather stations united in one app. When I'm at my home, I see the data from my own Netatmo weather station. It can't get much more local than that! Also here is a weather map summery. If you touch it, it opens the map full screen with lots of options, like past and present radar, overview of other weather station's data like temperature, rainfall & humidity. The smaller map on the main screen give you a quick preview of what might be in the area, along with the current readings of temps, humidity and winds.

Scroll down and you'll find my favorite part. The 10 day forecast chart. Here at a glance you can see the forecast by the day and hour for temperature and precipitation. Its not enough to simply know the high will be 50 degrees or that there is a 10% chance of rain. When? How long? What is the trend for the week? Its all here and very easy to visualize whats going on when. Now you can easily decide the best day AND the best time to mow the grass, wash the car, go skiing, run errands, sleep in, plant your garden, work on the roof, or whatever you have going on without even reading a single number. If its supposed to rain on your parade, at a glance you can see perhaps the rain might be in the evening hours. This is what makes Weather Underground so useful.  Its such a great tool for time management. Your time is valuable and once its gone its gone. Plan accordingly!

The desktop site is even better, adding wind direction with speed. The precipitation graph turns pink when there is snow or ice. Its worth keeping as an open tab on your desktop browser to help plan your daily and weekly activities.

Continue scrolling down on the app and you'll see more local data, along with a video library of weather related news and information.

Keep on scrolling... This screen shows  the sunrise & sunset times in a nice pie chart. Complete with first light and last light. Click on the Moon tab and you'll see moonrise, moonset, next full and next new moons as well as the current moon. Handy for us amateur astronomers!

Next we have Webcams nearby. Some people volunteer outdoor webcams so you can SEE conditions in realtime. You can even set favorites and share your own photos.

Finally we have some social media links, forums, and your own personal blog if you choose to do so. Below that will be info about the NEAREST hurricane or cyclone anywhere in the world, even if its 4000 miles away.

Final notes...

If you're interested in installing your own personal weather station there are many different weather stations to choose from. Many are expensive and complex to setup with limited ways to view and chart data. You can start simple like I did with a $149 Netatmo sensor set. This gets you indoor and outdoor temps, humidity, air pressure, as well as indoor co2 and sound pollution levels. Later you can add a rain gauge and wind gauge.  Netatmo also has their own unique app and webpage thats really cool and worthy of its own review.  Note that you can choose to keep your outdoor weather station data to yourself, or share it with others either through Netatmo or the wider community on Weather Underground. 

Here's some useful links.

Saturday, December 17, 2016

LG's 2016 4k OLED TV : My Initial Impressions

After our 50" Pioneer Plasma TV died, we decided to replace it was an LG 55" 4K OLED purchased at a Black Friday discount plus 5% cash back via credit card, tax free and shipped free. This thing is amazing, as it's contrast ratio is infinite, producing true perfect black levels. Its pixels can turn off 100%, which even a plasma pixel cannot do. The perfect blacks combined with enough brightness give it a dynamic range able to properly display HDR content - unlike some current LCD HDR displays. The color capability is also impressive. Standard 8-bit panels, give you 256 color variations for each Red, Green and Blue subpixels, which totals 16.7 million possible colors. Tack on 2 more bits, and you get 1024 variations of each color for over a billion colors overall. I was also impressed with LG's WebOS GUI and gyro propelled remote control. I was never a fan of integrated smart TVs, but this is a pleasure to use. It will even natively stream local stations via my SiliconeDust HD HomeRun networked tuner, albeit not as fancy as the Apple TV STB. A small detail I later noticed was that the clear plastic base makes it appear as if it was floating above my sound bar. Slick.

I can't get a great screenshot with my iPhone. You have to see it in person to fully appreciate the details!

The screen itself is about as thick as a car's side window! Then halfway down the electronics enclosure adds maybe 2 inches of thickness.

As far as the poor Kuro plasma goes, I'll attempt a repair it at a later date and if successful I'll install it in my workshop, or try to sell it locally. I hear there are still Kuro fanatics out there willing to pay more than a penny for these displays. 

Tuesday, November 15, 2016

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!

Thursday, July 3, 2014

Facebook Page

Join me for a social media experiment..

Please like my new FACEBOOK PAGE for more updates.

Thanks everyone!

Wednesday, April 9, 2014

Links of Interest #002

Why CDs sounds better than vinyl - Its all in the sample rate!

Roger Rusell's Speaker Wire - A History - Busting those wire myths. The bottom line is you want lots of copper. Everything else is marketing.

Rod Elliot's Article on Passive & Active Crossovers - Why a passive crossover will never be as good as an active one.

The High Life - An audiophile rants. While I agree with a few things and not others, its a short, fun read if you have a couple minutes.

Project Free TV - Find those TV shows you love. Online. Free.

And lastly I leave you with a music video. The is the Main Title from Star Wars, played by Jelani Eddington, on a majestic 50/80 Wurlitzer pipe organ at Sanfilippo Residence.

Wednesday, January 15, 2014

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!