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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!

Wednesday, January 1, 2014

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!




Wednesday, June 5, 2013

Links of Interest Series #001

The first installment of regularly posted links of interest that I stumble upon. I'll have a permanent link to show only these posts on the sidebar to the right. Enjoy!


The Best Turntable (Entry Level) $400

I need to try vinyl one of these days. Maybe this is a good starting point?

"After consulting experts in the field and reading countless reviews, the entry level turntable to buy today is the Pro-ject Debut Carbon. It comes with the best combination of tonearm and cartridge of the entry level models out there, and is built well enough that you can upgrade the cartridge or other components down the road without needing to replace the table first."


The Dynamic Range Database


Does that new album sound better on CD, Vinyl or HDTracks?  Find out here before you spend your hard earned money.


24/192 Music Downloads... and why they make no sense

A very good article on why you DONT want a high sampling rate. Open this in a tab and read it later if you don't have the time. Its worth it. I like articles that have solid science backing them up. This is one of them. I'll also link the video accompanying this article because it demonstrates how science backs up facts and dispels myths about DA/AD conversions. I hope Monty makes more videos like this.




Friday, May 31, 2013

Now Magneticmadness.com!

I finally worked out my issues between Google's blogspot service and my domain registrar. Something that is normally so easy turned out to be a huge hassle because I had two different Google accounts and didn't know it. The result now is you can reach this blog directly at www.magneticmadness.com

The next thing I want to announce is I am going to start making posts about electronics and technology projects in general, in addition to the audio/video. A lot of folks into audio and home theater tend to have interests in line with other things I'm doing and would love to write about, so why not broaden the bandwidth a hair and open it up to more visitors?

Also if you feel so inclined to donate to my blog or future endeavors with the audio system, please click the logo below to make a Paypal donation and you will receive my highest accolades!




Wednesday, May 15, 2013

Audiophool Cables



A humorous, yet serious rant about over priced audio cables. I didn't expect to laugh so hard. A worthy watch and a reminder of how gullible some people can be!





Sunday, April 21, 2013

Basspig's 2nd Annual Meet


I attended Mark "Basspig" Weiss's 2nd Annual B.A.S.S. meetup this year and had a great time, despite being a little under the weather with a headache and being late to arrive. He wrote a great summary of events so I won't type a redundant article, but I'll leave you with a reprint and some brief comments. I will add that there were also some interesting discussions on vinyl. Mark played back some digitally recorded demos of a how a laser turntable sounds vs. a standard electromechanical turntable. This later spurred some research on laser turntables and "high fidelity" records. Vinyl is a whole other world to learn about. While interesting, Its not something I'm going to get into. I do know one thing. I love the overhead Mark's system has and always enjoy hearing it. I have not heard any other system that has this powerful finesse. It reminds me of practitioners of Chen style Tai Chi who's art is calm and flowing but also deadly fast when needed. If there is one thing I'm reminded of that I need to do to my own system, it is to increase the displacement capability by several orders of magnitude. What a difference this makes, even at low volume levels. Stay tuned!


Mark's summary is as follows..


As with last year, our B.A.S.S. Meet was a great success!

Thank you to all who attended and brought so many great food items as well!

The main audio/video demo featured my Blu-ray productions of the Bridgeport Symphony Orchestra with Alex Beyer, performing Rachmaninoff's Piano Concerto No 3 in D minor, then the GBS performing Rachmaninoff's Symphony No 2 in E minor, (selected movements), then Allison Eldredge with the Boston Classical Orchestra, performing Saint-saens Concerto for Violoncello in A minor, then the Zambelli Ultimate Fireworks Blu-ray that I had the pleasure to capture from the launch pad, then I played a track from a Japanese soundtrack "The Weathering Continent" as a 2-channel Sonic Holography demo. Next up was a demonstration of the dbx 500 Subharmonic Synthesizer. For this demo, I used appropriate material lacking in fundamental bass (Average White Band "Pick Up the Pieces") and then gave an example of the absurd Bass Pig effect when you use it with Reggae music that DOES have some bass.

We took a break at the buffet and then returned to the Lab portion of the day where I demonstrated Bell Labs' new tri-tone test for Transient Intermodulation Distortion. We tested a Sansui AU-9500 against a Lepai 2020 amplifier. The results were colorful and interesting. The test setup consisted of three Tektronix SG5010 precision audio oscillators, outputting 10.05KHz, 9KHz and 20KHz, respectively, summed into a resistor network which fed each of the audio amps under test. I also performed traditional THD and SMPTE/DIN IMD testing. The Sansui easily tromped the Lepai on traditional tests, with ultra-low .028% THD, but the tables were turned when the tri-tone tests were performed, with the Lepai being an order of magnitude lower in TIM distortion than the Sansui.

And finally, I fired up the HP 8568B spectrum analyzer, connected to an outdoor antenna, and displayed the spectral mask of several FM stations, some with and without IBOC (In Band On Channel) or HD Radio digital transmission, discussing the effects on DX listening with the presence of the wider digital sidebands.

Our last guest showed a BD of Baraka on our big screen, which provided a colorful and sometimes disturbing look at life around the world, focused mainly around Asia.All in all, a positive experience, many questions and positive comments.




Wednesday, March 27, 2013

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