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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
Topic: Setup, Design, and Demonstration of a Home
Virgils 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.
Virgils 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
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
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
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...
A recent review of the CH
Precision P1 phono preamplifier ($48,000)
states Current amplification circuits
produce the best signal/noise ratios [for moving
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
A current amplifier output
has a very high impedance output but that is
a different story.
email me here
other meetings and notices which may be of interest
to BAS members
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.
has a new article here: Extracting
Numerical Data from an Excel Trend Line
Test Bench !
by Alvin Foster ! Click
the logo: >
BAS Headphone Test Article is now available
in the BASS VOLUME 25, ISSUE 4,
on Page 17, available HERE
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
|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,
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,
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
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; email@example.com).
Does anyone have a schematic (or any other
info!) for any Dunlop-Clarke Dreadnaught amplifier? Email Barry at firstname.lastname@example.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 email@example.com
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
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,
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. firstname.lastname@example.org.
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
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.
||CLV / CAV?
|Blade Runner (Director's
Anniversary Director's Cut)
|The Hunt for Red
|In The Mouth Of
|Raiders of the Lost
|Raiders of the Lost
|Star Wars: Episode
1 - A Phantom Menace
|Who Framed Roger
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;
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
- Panasonic RP-91D DVD player with JVB Digital
- 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
- Garrard RC88 turntable with Shure M3D cartridge,
in excellent condition.
- Sony XM-5046 car audio amp, 4x50W into