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Meetings and other Notices

The Boston Audio Society
Meeting Notice for Sunday, April 23, 2017
Time: 6:00 PM

Place: Home of Virgil Zaporteza, 3 Jennifer Rd, Lowell, MA 01854
Featured Guest: Virgil Zaporteza
Topic: Setup, Design, and Demonstration of a Home Video Theater

Virgil’s theater holds six people. It is next to his music room, which holds 3-4 people. While demonstrating the video system, the music room will serve as the holding place for those waiting to enter the theater. The wait will permit you to enjoy the best viewing/listening experience while inside the theater. The video room and equipment are designed for reproduction over a 5.1 speaker system. Food will be available for those hanging-out and socializing. Bring along your favorite video or CD.

Virgil’s home theater is located in the basement of his home. The basement location introduced special problems with noise isolation, ceiling height, and dealing with quality audio in a room made of concrete. As a system administrator, Virgil is familiar with the systematic approach to solving problems. One-by-one he supplied solutions to overcome the obstacles. He will share his setup, equipment selections, and problem solving solutions with us at the meeting. His setup consists of an Epson 8350 projector, Integra DTC-9.8, Marantz MM9000 amplifier, DIY Soundgroup Fusion 15s for LCR, and a Bill Fitzmaurice Tuba HT for a subwoofer.

Refreshments – Beer will be on tap as well as refreshments.at 5:30

Driving Directions – Take I-93 North to I-95 South. From I-95 S take US-3 North to Exit 32 toward Chelmsford. Turn right on Drum Hill Rd (signs for Lowell). Continue on Westford St and go over the Rourke Bridge. Turn left on Pawttucket Blvd. Turn right on Old Ferry Road. Left on Varnum Avenue and Right on to 3 Jennifer Rd, Lowell, MA 01854. It is the blue house with a flagpole on the corner.

GPS USERS: The GPS may take you to Bedford Ave. That road is closed, so you can take the road to the left (Lexington Ave) which is the other side of the large building and then the GPS will recalibrate and take you right to the house. On street parking is available.


BAS MICROPHONE CLINIC REPORT !
In September 2009 the B A S held a microphone clinic, testing 37 different microphone models. The ambitious nature of the clinic effort, the extent of data collection, the number of individuals involved in microphone testing and in writing various sections of the report, and the complexity in determining how to construct the clinic report and make it available to members resulted it not being published until now. The dataset is extensive.

Representative samples were included in the abbreviated report in "The B A S Speaker"
(Fall 2015; v37n3)

Go to the MICROPHONE CLINIC PAGE for more...


The BAS Message
April 2017

Current Amplification

A recent review of the CH Precision P1 phono preamplifier ($48,000) states “Current amplification circuits produce the best signal/noise ratios [for moving coil cartridges]”.
Their spec is -138 dBu [1 volt reference] with a 1 ohm source and 22 kHz bandwidth.

A current preamplifier responds to the current output of the source and has near zero input impedance*. A voltage preamplifier has a high input impedance and responds to the voltage of the source.

In a voltage amplifier the principal noise sources are the source resistance, the input transistor, and the feedback resistor to ground. In a current amplifier there is no resistor to ground; the source resistance is the feedback resistor. So one noise source is eliminated and the theoretical noise is lower. A side affect which may be beneficial is that the gain is inversely proportional to the source resistance, so the lower the source resistance the higher the gain. Since in general the low output MC cartridges also have low resistance, that is self compensating.

Is it low noise?

The DB Systems DB-4B head amp, introduced in 1976, specs -86 dB A Weighted [1 mV reference] That is -146 dBu, or about -143 with a 22 kHz bandwidth. So it is 5 dB better, using conventional voltage amplification. BTW the noise of a 1 ohm resistor is -154.4.

Note: This calculation doesn't take into account the RIAA curve which would give the DB-4B a few dB more advantage.

I emailed CH Precision on their website and got an error message.

*Speaking in terms of operational amplifiers, the + input is grounded and a resistor is connected from the output to the – input which is the summing node. The cartridge has one side grounded and the other is connected to the summing node which is essentially zero impedance and has no voltage associated with it.

A current amplifier output has a very high impedance output but that is a different story.


email me here


Below, other meetings and notices which may be of interest to BAS members

When collecting and plotting "noisy" data it is often useful to have Microsoft Excel plot a Trend Line through it.  If that data is to be used for further work, it may be necessary to have an X-Y table of the Trend Line. That is not easy to get and this paper will show how to do it.
Joseph DeMarinis has a new article here: Extracting Numerical Data from an Excel Trend Line

Foster's Test Bench !
by Alvin Foster !    Click the logo: —>
The rapidly-becoming-famous BAS Headphone Test Article is now available in the BASS VOLUME 25, ISSUE 4, on Page 17, available HERE   PDF 3mb
Visit our PODCAST PAGE for:
The LIVE video podcast of our meetings,
Archived video of past meetings (only one so far!),
and Audio Podcast interviews by Alvin Foster
There is a supplemental and further explanation addendum paper to the E. Brad Meyer / David Moran paper published in the September, 2007 issue of the AES Journal. That page, which documents the experimental protocol and audio systems/source material is here:
www.bostonaudiosociety.org/explanation.htm   
There is a Power Point Presentation of the lecture given by Dr. Barry Blesser at the March 2007 Meeting. The Meeting page synopsis is HERE; the Power Point Presentation (as a web page) is HERE

Some earlier BASS issues, previously available only directly by mail, are now available online, on the BAS SPEAKER page, HERE

Show your appreciation for the immense amount of dedicated work that went into both the original writing, gathering, editing and printing, PLUS the more recent scanning and conversion to PDF format, by joining the Society, HERE !


A L L   O F F S I T E   L I N K S   O P E N   I N T O   A   N E W   W I N D O W

- AND FOR CONVENIENCE -

AES Future Meetings
www.bostonaes.org

Acoustical Society of America
www.gbcasa.org
SMPTE New England
www.smpte-ne.org

There is a posting of an ABX article, The Digital Challenge by Stanley P. Lipshitz HERE


Classifieds
( A new section! Watch for a full page coming soon ! )
NOTE: offsite links open into a new page.
BAS Members may SELL items here; anyone may BUY.

The Boston Audio Society needs individuals who will write summaries of BAS meetings into *.pages, *.doc, or *.txt files. We usually have audio recordings of the meetings. We pay for your work. Ask about our bonus program for meeting-writers! Contact David B. Hadaway (603-899-5121; dbsys22@att.biz).


Does anyone have a schematic (or any other info!) for any Dunlop-Clarke Dreadnaught amplifier? Email Barry at webmaster@bostonaudiosociety.org


For sale: Audio Precision System 1 audio test system. SYS-322A, s/n SYS1-31968, IMD, BUR, W&F options, A-weighting filter, PCI interface card, rackmounts; asking $5000. Contact Mark Chambers machambers@charter.net


For sale: Several CD storage racks, some made by Bostonwood (www.BostonWood.com/cd.html): Two four-shelf units (25.5"Hx17"Wx5.5"D); One four-shelf unit (25.5"Hx24"Wx5.5"D); Two three-shelf units (19.5"Hx17"Wx6.5"D); one home-made three-shelf unit (18"Hx14"Wx6"D). I have attached a handle and chains to several units, making them convenient open-top carriers. David J. Weinberg (Maryland; 301-593-3230).


Seeking a two-channel preamplifier such as an Apt Holman, an early Hafler, or an early NAD. Must work properly. Fred Ampel (FAmpel@KC.RR.com).


Seeking prereceord Advent cassettes, especially Russell Sherman Beethoven and Liszt recordings, and Handel's Messiah performed by the Handel & Haydn Society under Thomas Dunn. David R. Moran (DRMoran@aol.com).


I am disposing of all my old copies of the BAS Speaker, which go back to 1978, more or less complete. I am going to recycle these with waste paper unless somebody wants them for free. I'll even pay shipping. Doug Pomeroy Audio Restoration & Mastering Services audiofixer@verizon.net


Discography of Test Records. I am compiling a list of technical test records from all recording eras and would like to exchange information in order to confirm, expand, correct and add entries. Send me your list and/or other information about test records and I will send you my discography, which has nearly 200 entries to date. I am interested in commercially released records, as well as discs intended primarily for in-house use by audio engineers, broadcasters and for other special applications. I am generally excluding demonstration discs of the "Super Stereo bouncing ping-pong ball" type unless they include at least some tracks of a technical nature, such as frequency response and tracking tests, etc. Nicholas Starin, Portland Oregon, NTSTestDisc@Gmail.com.


Nashville AES Test CD. (www.AESNashville.org; click the small round symbol where it says "Click here for more info:" to download the four-page description and track list. Use the link on the website under <Products> to send an email for pricing and availability.) From the website: "Assembled 'by engineers, for engineers' after a survey of the needs of a broad cross-section of working audio pros, the disc features 71 tracks of test signals ranging from level calibration tones, noise signals, third-octave tones, polarity and digital meter calibration pulses, bandpassed noise and swept sinewaves. Additional tracks include dry-recorded kick and snare drums, acoustic guitar and piano along with spoken word and a cappella male and female vocals. A data area on the disc features BPM charts, Excel-based calculators and other bonus material. The CD booklet includes tutorial information on using the test disc."


For sale: Three Denon DR-M34HR cassette decks ($500srp) with three heads and live monitoring of the recording, dual Dolby B/C and Dolby HX Pro circuitry. Handles normal, chrome and metal-tape cassettes. Highly regarded in 1988. Gasparo Records used them as duplicators. In good shape. Data at www.VintageCassette.com/denon/dr-m34hr. $125 ea+shipping. Contact David B. Hadaway. dbsys22@att.biz.


For sale: Arcam Solo Movie 5.1 (www.Arcam.co.uk/products,solo,Movie-Systems,SoloMovie51.htm; $4500srp) The manual is downloadable from the Arcam website. I do not have original packaging. $1000+shipping, which will be calculated once destination is determined. Funds transfer or cash only; no checks. Fred Ampel (FAmpel@KC.RR.com).


For sale. Two Tannoy HPD 315 speakers, made in the mid-1970s, woofers might need refoaming. Steven Weiner (SDWeiner@ATT.net; 818-865-0601; Thousand Oaks, CA) is asking $500+s/h. [I have seen a photo; the cabinets and grill look to be close to mint condition. This ad was placed at the request of member Randy Hoffner. DJW]


Seeking: Soundfield Mark IV microphone. Jim Mastracco (James.Mastracco@Verizon.net).


Laserdiscs for sale by David J. Weinberg (301-593-3230; WeinbergDJ@BostonAudioSociety.org) Four have Dolby Digital 5.1 soundtrack. Nine have DTS5.1 soundtrack. Make offer for all or selected items.

TITLE CLV / CAV? ASPECT
RATIO
Video Essentials    
Apocalypse Now CLV 2
Apollo 13 CLV 2.35
Batman (Michael Keaton) CLV 1.78
Blade Runner (Director's Cut) CAV 2.48
Blown Away CLV/CAV 2.35
Crimson Tide CLV 2.35
Daylight CLV 1.85
Evita CLV 2.35
Forbidden Planet CAV 2.35
Golden Eye CLV/CAV 2.35
The Grifters    
Highlander (10th Anniversary Director's Cut) CLV/CAV 1.82
The Hunt for Red October CLV 2.35
In The Mouth Of Madness CLV 2.35
Jurassic Park CLV 1.85
Jurassic Park CAV 1.85
Phenomenon CLV 2.35
Pocahontas CLV 1.66
Pretty Woman CLV 1.85
Raiders of the Lost Ark CLV 2.35
Raiders of the Lost Ark CAV 1.33
Star Wars: Episode 1 - A Phantom Menace    
Toy Story CLV 1.78
Who Framed Roger Rabbit CLV 1.75

Own a movie theater sound system! For sale, top-of-the-line High Performance Stereo HPS-4000-XL screen speaker systems. Three (left, center, right) HPS model 545-4 speaker systems (www.HPS4000.com/pages/fivefortyfive_.html) and two HPS model 545-W subwoofer speaker systems (www.HPS4000.com/pages/545_w_.html). All in perfect working order. The speakers are not light, but consist of modules that can be lifted by two moderately strong men. Truck delivery only, or come pick up. Make me an offer. David J. Weinberg (301-593-3230; WeinbergDJ@BostonAudioSociety.org):

Most units come with user manuals (some also with service manuals), remotes and cartons, as applicable. Make offer:

  • ReplayTV 2020 with aftermarket larger disk drive. Includes lifetime electronic program guide service.
  • Faroudja VP400A video quadrupler. Upscales NTSC video to 960 progressively scanned lines for a front or rear CRT projector. Generates great image on my big screen. I don't need it because I'm modifying my video system.
  • Runco 980Ultra CRT projector (original packing, user and service manuals).
  • Vutec concave high-gain silvered screen. 8' wide, 16:9 aspect ratio, with wallmount brackets. Silvered surface makes it appropriate for 3D projection, as the high gain overcomes the substantial light loss caused by the various consumer 3D projection technologies, and the curved shape can deliver a wide viewing angle with little hotspotting.
  • Lexicon DC1 surround processor, with all options.
  • Panasonic RP-91D DVD player with JVB Digital regionfree mod.
  • Sony DVP-NS755V SACD (multichannel and stereo), DVD, etc., progressive-scan output. $250srp.
  • Tektronix D11 rackmount single-beam storage oscilloscope with 5A15N vertical amp and 5B10N time-base/amplifier.
  • Tektronix 5111 rackmount single-beam storage oscilloscope with two 5A18 vertical amps and 5B10N time-base/amplifier.
  • Teac AN-180 external dual Dolby B processor. Simultaneous stereo record and playback.
  • Pioneer CT-F4242 cassette deck, in excellent condition.
  • Garrard RC88 turntable with Shure M3D cartridge, in excellent condition.
  • Sony XM-5046 car audio amp, 4x50W into 4 Ohms

Webmaster's Corner:
Once again, for 2017 - and on through 2020 (!) here is THE useful industry calendar of audio/related events, with kudos to any and all who put this list together: www.stiernberg.com/industry-calendar

Barry

 

The Boston Audio Society
PO BOX 260211
Boston MA 02126


updated 4/9/17