On LED Flashlights…

By Bryan Geyer

The innate connection between a flashlight and “Audio Tech
Talk” becomes apparent as soon as you try to inspect any part of your sound
system that lies beyond the front panel. In recognition, here’s some personal
guidance about the most vital tool you’ll ever need: A modern single-cell LED
flashlight.

First, learn why the light emitting diode (LED), a
semiconductor device that dates to the late 1960s, didn’t become abundant in
flashlights until some 30 years later. What a curious delay! What happened? And
what changed? Well, a modern “white light” LED won’t fire until it sees a
threshold bias of about 3.2 volts minimum, and 4 volts or more works better.
But a fresh single cell battery produces only ~ 1.2 to 1.7 volts, dependent on
its chemistry (see footnote*), so multiple batteries would be needed to
fire a solitary white light LED. Clearly, using more batteries than before
didn’t advance the state of flashlight design, so miniature incandescent lamps
endured. Then, barely before year 2k arrived, integrated circuit “boost chips”
appeared. These new silicon ICs could efficiently elevate the energy from a
single storage cell to the operating level needed to fire a white light LED.
The basic design concept was old, but implementing it in IC form was
breakthrough genius. The entire boost function, consisting of the surface-mount
chip plus some tiny passive peripherals, could now be packed into a bundle
smaller than the size of two stacked dimes. A practical single AA cell LED
flashlight was suddenly viable, and its launch assured immense advantage over
anything using an incandescent bulb. A lone LED could now provide more light
(with selectable lower levels), draw less current, offer high resistance to
shock and vibration, and assure decades (not hours) of maintenance-free service
life—all while selling at competitive mass-market prices.

Product development was intense, with many players engaged.
Some failed, some flourished, and several smart trans-Pacific sources became
dominant. There’s now a wide array of LED flashlights and multi-LED lanterns on
the market. Many designs serve niche applications, but my intent here is to
feature a basic everyday flashlight—a modestly priced model that’s appropriate
for general purpose use and practical in-pocket carry. A flashlight that…

…is short (≤ 3.1" long), skinny (≤ 0.75" diameter),
and uses only a single AA size cell.

…is blindingly bright at full output, with multiple lower
levels to conserve current drain.

…has long throw capability, with enough side spill to see the
borders of your path at night.

…is obvious in operation, with a single butt-end control
button for all switching functions.

…offers instinctive battery exchange: unscrew head and
replace AA cell, button end up.

…has solid mechanical integrity; built to withstand the
rigors of moderate abuse.

…if supplied with a pocket clip, such clip must be readily
removable and leave no evidence.

… meets the IP68 waterproof standard (up to 30 minutes at
depths of ≤ 2 meters).

…is cheap enough stash extras (toolboxes/cars/bikes/garage)
and give as gifts.

There aren’t a lot of candidates that meet all of my
objectives. Many come close, then fail the “side spill” criteria. That’s
because flashlight marketers always hype throw (range), and inexperienced
buyers focus on that feature; they haven’t yet grasped the importance of spill
(beam spread). The two parameters (throw and spill) are mutually exclusive;
more of one means less of the other. A very tight beam will deliver impressive
reach, but hot spot fixation invites personal risk when you can’t see the edges
of a narrow path from just one step away.

My pick as a good “everyday” single AA cell flashlight is the
Fenix E12 Version 2.0. It meets all of my criteria, and you can buy it
here: https://www.fenix-store.com,
or here: https://www.batteryjunction.com
The Fenix E12 V2.0 flashlight offers three selectable outputs: 5, 30, and 160
Lumens. It uses a cool white LED, and has an ultra-thin (3mm) optical front
lens—all very desirable. The lowest level is appropriate for checking your
watch in a darkened theater or finding a keyhole at night. The mid-level
setting, 30 Lumens, assures a practical balance between output and capacity.
It’s great for all of your “fix it” tasks, also for walking at night. The full
160 Lumen output provides a brilliant spotlight, but keep it brief! Apply only
in 10 to 20 second transient bursts. At this level, supply current is consumed
at a rapid rate, and there’s significant internal dissipation (heating). As
with many LED flashlights, these output levels are all electronically
regulated, so the lighting intensity stays constant; it won’t droop as the AA
cell ages. Full expiration becomes suddenly apparent; it’s dependent on the
drain that’s required for the level you’ve selected. When the supply current is
insufficient for a given level, the output will drop to the next lower level.
When it’s too low to maintain the regulated 5 Lumen minimum, the output drops
to a useless glow, then goes out.

The Fenix E12 V2.0 flashlight comes with an attached (by
compression) pocket clip that I dislike, so I trash it. This is easy to do with
the aid of pliers—just grab the clip and pull it off. It will readily detach
and leave no evidence that it was once mounted on the flashlight body. This
flashlight is so small and light that a pocket clip isn’t of practical benefit;
however, removing the clip will then expose a perfectly cylindrical body, and
round stuff that’s not restrained can roll off flat surfaces. If this annoys
you, consider mating a wrist strap to a rear lug. Straps that have a small
pigtail loop at the end will pass through the lug without impeding the control
button.

BATTERY OPTIONS: AA cells are readily available in the
variants (3) noted below*, but you’d do well to reject the use of
alkaline (manganese dioxide) LR6 cells. These conventional cells are very
popular, but too risky to merit informed consideration. When an alkaline AA
cell approaches expiration (output ≤ 0.7 volts), it will progressively
destabilize and form a caustic compound (KOH, potassium hydroxide) that will
penetrate the outer shell and attack anything that’s within reach. The
consequent damage can be severe. This is an inherent flaw—all alkaline cells
present this same inevitable hazard—so don’t use alkaline AA cells.
Instead, select either of the other options. I use the non-rechargeable
lithium-iron disulfide Class FR6 cells, e.g., Energizer’s “Ultimate”**.
Others prefer the rechargeable nickel metal-hydride (NiMH) Class HR6 cells.
Both options are safe, don’t leak, and work well. Non-rechargeable lithium AA
cells exhibit extended operating life, perform well in cold ambients (alkaline
cells don’t), weigh about 40% less than the alkaline equivalent, and can
tolerate long term (10 years) passive storage with minimal (5%) net
self-discharge. Buy in bulk, stow for use as needed.

* The nominal AA cell output voltage,
when fresh (or freshly charged), is…

…1.5 volt for a non-rechargeable alkaline (manganese dioxide)
IEC Class LR6 cell.

…1.2 volt for a rechargeable nickel metal-hydride IEC Class
HR6 cell.

…1.6 to 1.7 volt for a non-rechargeable lithium-iron
disulfide IEC Class FR6 cell, e.g., Energizer “Ultimate” AA cells.

IEC = International Electrotechnical Commission

 ** I buy on-line, from Battery Junction;
refer… https://www.batteryjunction.com/energizer-aa-ln91-24pk-battery.html

BG (December 2022)

On Upgrading What’s Analog…

By Bryan Geyer

THE POSIT—Recent
technology advances make it practical to upgrade select analog functions in
many conventional stereo systems. It’s now possible to…
…dramatically extend the range and enhance the
linearity of low bass response.
…materially reduce the mass of the main
speaker enclosures.
…clarify the midrange response by isolating it
from low bass modulation.
…eliminate archaic high-level passive
crossovers that reflect only low order filter slopes.
…enable precise line-level active
crossovers with full 4th order (-24dB/octave) attenuation.

BACKGROUND—The
pursuit of good sound is evolutionary, but the conviction that high fidelity
= big speakers persists. Low frequencies have long wavelengths (28 feet at
40 Hz), so big transducers, in big enclosures, have always been considered
essential to reproduce, propel, and propagate big bass. Regardless, monstrous
monkey coffins that require prominent front-and-center placement look absurd in
domestic living rooms, so reasonable compromise is vital. The usual course is:
(a) downsize the speakers, or (b) always entertain outside, or (c) cram the
system into a “man-cave”, even though the main LR offers superior acoustics
(lower Schroeder frequency), or (d) use headphones only. These are odious
options; let’s pursue better.

WHAT’S CHANGED—In the
mid ’90s, the push to popularize home theater became dependent on finding a
practical way to recreate Godzilla’s footfall while squeezing the mass out of
the additional speaker enclosures. This paradox looked hopeless until design
guru Bob Carver, then at Sunfire, proposed his astonishing new (1997)
self-powered “True Subwoofer” as a viable solution. Market acceptance was slow
until Sunfire’s patent grip was softened; then the trade piled on. The new subs
could pump out pure (low harmonic content) 30Hz sine wave bursts at pressure
levels exceeding anything previously envisioned. Today, relatively compact
subwoofers with only a single 10" or 12" diameter driver (e.g., https://www.jlaudio.com/collections/home-audio-e-sub/products/e112-gloss-home-audio-e-sub-powered-subwoofers-96279)
can produce lower, louder, and cleaner bottom bass (the two bass octaves
below 80Hz) than the very best, biggest, and most expensive full range
floor-standers ever built by anybody, anywhere.

Tempering this marvel
is the reality that these new self-powered subwoofers excel at just one thing:
They can handle those two bass octaves better than any conventional woofer.
They’re able to do that because they’re expressly designed for a single,
solitary mission. They have extremely deep, ultra stiff cones, long and
compliant surrounds with extended x-mass capability, and they’re driven by high
power class D amps that apply carefully contoured equalization. Unlike the
woofers in a costly full range floor-stander, the “sub” doesn’t have to produce
any appreciable output above ~ 140Hz. Conversely, a conventional full range
floor-stander is designed with the expectation that it must also cover the full
low-to-middle bass range, commonly extending to frequencies approaching ~
800Hz, and do so with good linearity. That’s a stringent additional assignment.

TODAY—If the intent
is to achieve optimal fidelity, we need to reconsider how stereo systems should
be configured. Clearly, paired stereo subwoofers* should handle the
bottom bass octaves. The main stereo loudspeakers can then be reduced in size
to reflect the fact that they will no longer have to reproduce those
subterranean sounds. Stand-mount main speakers with 6" to 8" drivers
have proved absolutely optimum. Excellent bookshelf-size speakers, like Harman’s
Revel Performa M126Be (https://www.audioholics.com/bookshelf-speaker-reviews/revel-performa-m126be),
or the Revel M106 (https://hometheaterhifi.com/reviews/speaker/bookshelf/revel-performa3-m106-2-way-bookshelf-monitor-loudspeaker-review-part-one/),
come to mind, and they confer welcome decor relief. The related subwoofers are
best placed near the front corners of the room, at or near floor level, where
they’re generally easy to accommodate. There’s simply no need, anymore, for
monstrous four to five foot tall main speakers that are packed with multiple
10", 12", or 15" woofers. At least, not unless you’re personally
committed to high-end electrostatic-type speakers, such as those
championed by Sanders Sound Systems. (In that event, please see https://classicalcandor.blogspot.com/2019/09/on-elephants-in-room.html.)

In addition to the
cited decor benefit, separating the low bass from the upper bass presents a
compelling aural upside. In a conventional setup, the main woofer and its power
amplifier handle both signals, so there’s often some mild modulation blur of
the upper bass or lower mids when the score calls for a sudden burst of big
bass thunder. Routing that sound directly to the low-pass amplifiers, inside
the self-powered subs, means the main speakers will now be unaffected. The main
power amplifier will never see those low bass signals when they’re appreciably
below the crossover notch. Eliminating this potential midrange modulation is
one of the most vital rewards that you can claim when you add subwoofers and
install an external active crossover. Some listeners feel that the midrange
benefit is even more audible than the subwoofers’ bass extension. Your own
impression might be a bit program-dependent in sensing these complementary
improvements, but it’s clearly evident when the score fits**.

MODERNIZING
CROSSOVERS—A further concern is that conventional full-range speakers impose
the need for accurate driver-level crossover networks. Such filters are
fussy to design and awkward to assemble. They’re wholly dependent on precisely
defined R/L/C components that must pass high current signals to low impedance
loads. Tight tolerance passive parts of this unique nature are rare—most have
no other fundamental application in the scope of the electronics trade, so they’re
often difficult to obtain in the exact values that are needed. The inevitable
consequence of this difficulty is compromise, and compromise breeds inaccuracy†.
Even when they’re effectively designed and constructed, these high level
crossovers often prove inadequate because they’re typically just first order or
second order (-6dB or -12dB/octave) filters with gentle attenuation slopes.
Full fourth order (-24dB/octave) passive crossover networks would be more
suitable, but they become impractical (too complex, physically prohibitive) for
high level (low impedance) applications.

The solution to this crossover dilemma is to move that
function from its classic position, between the power amplifier outputs and the
various driver inputs (where it must process high level signals), to an
earlier point, prior to the power amplifier, where the components will
see only lower line level signals.This
preferred location assures ready access to lots of stable, tight tolerance
R/L/C components of virtually any desired value. When combined with active
op-amp circuitry it’s then possible to form highly selective Linkwitz-Riley
type filters with full 4th order attenuation slopes. The penalty implicit with
inserting the crossover in this line-level position is that a separate power
amplifier will now be needed to connect each crossover output (high pass and
low pass) directly to its designated driver. That means operating in “bi-amplifier”
mode, a form of connection that confers useful advantages; e.g., better load
(driver) damping; also the ability to independently dictate the signal
amplitude sent to each power amplifier.

A fully external
(meaning separately enclosed and powered) active crossover controller is
invaluable when adding supplementary self-powered subwoofers. The active
crossover’s high-pass outputs can feed the main stereo power amplifier +
main speaker system, while its low-pass outputs feed the line inputs on
the self-powered subs. (The active crossover thereby supersedes any built-in
low-pass filtering that might be a part of the sub’s internal circuit, so the
subs should then be operated in their selectable “bypass mode”.) This setup
facilitates convenient adjustment of the “mains-to-subs” dominance (the
relative output levels of the main speakers compared to the subs) from a
single, central location. Without this crossover controller you’d need to crawl
to each individual subwoofer and separately adjust their input sensitivity
controls—and repeat that crawl every time you want to tweak the mains-to-subs
settings or alter the relative channel balance.

An external active
crossover controller with variable frequency capability will allow the user to
position the crossover notch at a point that’s optimum for the main speakers in
use. For most subwoofer setups, this will involve a setting that’s somewhere
between ~ 76Hz and 100Hz. (Lower crossover frequencies are not advisable,
regardless of the main speakers’ perceived bass capability.)

Loudspeaker systems
with internal line-level active crossovers + self-powered class D amps
are already in common use as near-field monitors; also as desk-top setups.
Designs of this nature offering higher power output have also appeared, e.g.,
the “Kii Three”. Clearly, this trend will accelerate. We’re going to see lots
of analog circuitry integrate with the loudspeaker, and some of the speaker
makers are likely to merge with those that currently make power amplifiers. Of
course, vacuum tube power amps—already a moribund species—will then fade forever.
Ditto for big solid-state quasi-class A power amps and heavyweights that
resemble engine blocks. Niche products will always exist, but it’s doubtful
that those who make them will prosper and survive, so be wary about where you
hitch your wagon.

THE PREAMPLIFIER—Refer
https://classicalcandor.blogspot.com/2019/12/on-controlling-volume.html.
Amen.

Footnotes…
*Paired stereo subwoofers (not a solo “shared
bass” subwoofer) are essential for acoustic advantage; refer https://classicalcandor.blogspot.com/2019/03/basics-about-bass_20.html.

**Re. “when the score fits”…is a phrase
that brings to mind a subwoofer quirk that you need to know. Many (all?) of the
companies making self-powered subs provide the useful ability to select
automatic “signal sensing” as a means of activating the sub’s internal power
amplifier; i.e., to auto-awaken the sub from its passive sleep state. In sleep
mode, the sub stays on, but it dissipates minimal power until it perceives that
it’s time to rumble. The sub then goes into active mode, and remains active
until there’s no input signal for an appreciable duration, e.g., 20 or 30
minutes. An initial problem is sometimes evident with respect to the maker’s
signal-sensing level. Bear in mind that the sub can only hear very low
frequency signals because its line-level input path is through a low-pass
filter. When there’s persistent heavy bass (as with virtually all pop music
today), the sub will awaken quickly. But when the bass content is evident only
where Mozart scored it, that sub might not awaken (go active) until you’re a
third through an extended concerto. Classical music just doesn’t exhibit the
same pounding bass line that persists with pop. Unfortunately, the folks that
make subs think classical music is extinct, so they normally set the signal
sensing to trigger at a higher (less sensitive) level than what’s optimum for
classical format. In many cases the original factory setting is as much as 14dB
to 16dB too high (too insensitive). So—when you buy a sub, communicate with
your supplier. Have the maker set your subs to auto-activate when The Lark [is
barely] Ascending. (I bow to Mr. Vaughan Williams.) If they fail to do
this you’ll then need to return your subs to the source, and have a factory guy
readjust the trip point (warranty return, maker’s expense). With all of the
subs that I’ve seen, this setting is always an internal adjustment. Some subs
might now make this tweak externally accessible, but internal-only is more
logical because it’s a “set once” consideration, and external access invites
misuse. Home-based DIY readjustment is definitely not feasible. The internal
class D “plate amp” has complex multi-layer boards + tiny surface-mount (not “through-hole”)
components, and that makes this simple task too risky when no schematic is at
hand.

Be assured that there’s
no downside related to increasing the subs’ activation sensitivity. When your
external active crossover controller’s low pass outputs (to the subs’ inputs)
cease sending a source signal (for the specified time lapse) to the subs, they’ll
automatically revert to their dormant sleep mode, exactly as intended. The only
instance in which this might not happen is if your crossover controller
suddenly became intolerably noisy—with noise so annoying that you’d be fully
absorbed with that fix before noting that the subs didn’t go to sleep.

†It’s only natural that those who own big
full-range floor-standing speakers would assume that the internal high level
crossovers buried inside their costly purchase are both optimum and accurate.
Regardless, their faith is likely misplaced. Accuracy is certain to be deficient
in the case of passive networks that have accumulated appreciable use because
passive high level crossover components drift. High level operation = high
level stress. (Refer paper headed “On Crossing Over,” at https://classicalcandor.blogspot.com/2020/01/on-crossing-over.html.)

BG (April 2021)

Legacy Audio Powerbloc2 Power Amplifier (Amplifier review)

Manufacturer: Legacy Audio, Springfield, IL USA  (800) 283-4644

www.legacyaudio.com



By Karl W. Nehring

Legacy PB2, front

Before commenting on the specifications and performance of the Powerbloc2 power amplifier from Legacy Audio, let me first establish some historical perspective. Back in the late 1970s when I was a graduate student with a growing family, a passion for audio, and a limited budget, Sony released a revolutionary pulse width modulation (“Class D)” power amplifier, the TA-N88B, which was the first such amp to be commercially available. Through a simple twist of fate, I happened to run across a brand-new TA-N88B that an audio store in the area was selling for somewhere around half the standard retail price of $1,200 (which would be more than $4,000 in 2020 dollars). Although at the time I did not have an extra $600 lying around, I just had to have that amp, so I wracked my little brain to come up with a way to get it. (A legal way, that is – breaking into the store in the wee hours of the morning was not a viable option.)



The legally valid plan that I came up with led me to the office of our local bank, where I talked to the manager and explained to him that I had found an incredible deal on this piece of audio equipment. If he would lend me the cash to purchase it, I would be able to pay him back in installments, or else I could sell the thing for more than the purchase price, pay him back with a bit of interest, and we would all be happy. Believe it or not, he bought my story and made out the loan. Small-town (actually, not even a small town – a rural village), old-school (four decades ago, recall) friendliness at its finest. Alas, our local branch shut down long ago, the local bank got swallowed up by a larger one, and I am certain it would be not nearly as easy nor informal today. (Of course, in today’s world, when we want something we can’t afford, we just whip out the old credit card, right?!)



Why was I so desperate to buy this amplifier, besides the fact that it was for sale at such a low price? It might be hard to imagine nowadays, when Class D power amplifiers (and power amp stages in receivers, integrated amps, and powered speakers/subwoofers) are quite common, just how radical the idea seemed when the Sony was introduced. Here was an amp the used then-new V-FET transistors (a term that subsequently disappeared) as switches – the job that transistors are actually best at – amplifying the audio signal. Crossover distortion was no longer a factor, it put out 160 watts per channel, ran cool both at idle and when driven hard, and came in a sleek physical package about the size of a preamplifier. The “B” in the nomenclature indicated a unit with a what Sony called a bronze finish, a kind of light gold or champagne color that was simply gorgeous. Later, most of the units imported to the U.S. were the TA-N88, which featured a more mundane silver color scheme. At about 25 lbs., it was not heavy for a power amp of its output capability, and there were no sharp heat sinks to cut your fingers.

Legacy PB2, rear

The specifications for the Sony amp do not seem very good by today’s standards, but in the late 70s/early 80s, they were nothing to be ashamed of. The amp put out 160 watts per channel into 8 from 5 Hz to 40 kHz with no more than 0.5% THD, damping factor was 20, S/N ratio was 110 dB. Yes, the damping factor was pretty low, and the THD a bit high, but those specs compared well to tubed power amps of the day, and these were the days when tubed power amps were considered the hot setup. But the Sony put out more power, ran much cooler, and weighed much less than any decent tubed power amp. It would fit in your room and not heat it up.



Well, it sounded pretty good in my system back then, driving KEF 105s in the same listening room that I use today, but I did not keep it for long. I soon sold it for $800 or so, paid off my loan, and put some money in my pocket. Why did I keep it for so short a time? Two reasons, really. First, I did not really trust the technology. I always had the sense that the thing was running at the ragged edge of reliability. Second, it was rated for a minimum speaker impedance of 8. At lower impedances, that already narrow treble bandwidth would droop even more as a consequence of the passive output filtering Sony used to keep the high-frequency energy produced by the switching frequency of the amp out of the speakers.



The Sony was on the market for a few years and then disappeared. The failure rate was high and replacement parts became hard to find. But four decades later, there have been significant advances in technology, and the Legacy Audio Powerbloc2  is rated at 325 watts per channel into 8 ohms and 650 into 4, 1.5 Hz to 70 kHz, damping factor of 1,000, S/N of 117 dB, and weight 13 lbs. Compared to the Sony, then, the Legacy amp has twice the power, two orders of magnitude less distortion, nearly twice the bandwidth, a 50X better damping factor, and the ability to drive low-impedance speakers. The amp is a dual mono design, each channel with its own 30-amp power supply. Moreover, the Powerbloc2  at $1,800 costs less than half what the Sony would cost in today’s dollars.



So, after all that, how does the amp perform? Very well indeed. Over the years I have owned and auditioned many power amplifiers by virtue of my decades as a reviewer and editor of an audio magazine. Most of these I have auditioned in my own listening room, but I have also auditioned my amps in the systems of friends and audio dealers (remember those?). At the time I obtained the Powerbloc2 for audition, my reference amplifier was the Audio by Van Alstine (AVA) FET Valve 550HC, a 275 wpc Class A/B design with a hybrid tube/FET input stage driving a MOSFET output stage. Of all the amps I had ever employed in my system, it offered the best sonic performance.



When I compared the AVA with the Legacy, I preferred the sound of the latter, which just seemed to be slightly cleaner in the trebles and slightly tighter in the bass without giving up any of the glorious midrange provided by the AVA  What the Powerbloc2 did for beautiful choral recordings such as The Suspended Harp of Babel by Cyrillus Kreek or Translations by Eriks Esenvalds was simply breathtaking, revealing the nuances of voices in space better than I had ever heard. No, I am not talking about “night and day” differences, I am talking about subtle shadings of difference. I am not one to claim that all amplifiers sound the same; however, I do believe, a belief bolstered by many years of direct experience, that the differences between competently designed amplifiers of similar power ratings are largely indiscernible and subtle at best. If you hear a big difference between two such amplifiers, chances are you are in fact hearing differences in volume level between the two amplifiers, an amplifier with some sort of problem, or your own prejudices or imaginings.



Still, listening to the Powerbloc2 driving my Focus SEs has been a truly rewarding experience, especially on the large orchestral music that I love by composers such as Mahler, Bruckner, Shostakovich, Vaughan Williams, Sibelius, Elgar, Arnold, Ravel, etc. An especially revealing and rewarding musical experience for me recently was listening to the SACD version of the Mahler Symphony No. 2 (“Resurrection”) with the St. Louis Symphony Orchestra on Telarc. Not only were the big sounds rendered cleanly and powerfully, but the near-silent moments such as when vocalists and/or chorus would enter after a pause were simply sublime. The Powerbloc2 excelled at both ends of the volume scale of this excellent recording. On completely different sorts of music, such as the acoustic guitar shadings of Ralph Towner, the modal jazz on Miles’s Kind of Blue, and Vikingur Olafsson’s expressive piano stylings on Debussy-Rameau, the Poswerbloc2 made the music come alive without fail.



Incidentally, after spending a good amount of time enjoying music with the Powerbloc2 in my system, I decided I would like to try the Goldpoint SA-4 “passive preamp,” which has been recommended in Classical Candor by both John Puccio and Bryan Geyer. Having been perfectly satisfied with my Legacy Audio StreamLine preamp (no longer available) for quite some time (again based upon auditioning many units over the years, including solid-state, tube, and hybrid units of great repute), I was not expecting any sort of noticeable – much less “revelatory” – sonic improvement. To be honest, I was motivated primarily by the idea that a passive unit would never present any problems caused by capacitors or other parts in an active unit eventually falling off in performance or, worse yet, failing, and secondarily by my knowing a music lover/audiophile friend who had expressed an interest in acquiring my preamp should I ever be inclined to part with it. With these factors in mind, I auditioned the Goldpoint, found that it performed just fine in my system, possibly even offering a slight bit more transparency and clarity overall.  Once convinced of the impeccable performance of the Goldpoint, I sold the StreamLine and am perfectly content with the way my system sounds. For those with turntables, of course, the passive controller route is not a viable option, but for those whose source material is exclusively digital, the Goldpoint is certainly an attractive alternative to a high-quality, big-buck preamplifier.



Back to the Powerbloc2. What a wonderful amplifier and what a solid value! No, $1,800 is not inexpensive, but if you are a classical music lover (especially of large-scale orchestral works, opera, or organ music) with audiophile leanings who is looking for a terrific sounding amplifier with this kind of power and an  ability to drive difficult speaker loads, the choices available to you are not many, and if you want an amp that can do so while running relatively cool, taking up little space, and weighing so little while still being solidly built (e.g., premium input and output connectors, a rugged metal case, and a confidence-inspiring on/off switch), I know of no real competition for this amplifier at anywhere near this price.



KWN

Goldpoint SA4 Passive Preamp Review

Why doesn't anybody tell me these things?



By John J. Puccio



Well, they did. When I bought my current speakers, VMPS RM40s, the designer of the speakers and owner of the VMPS loudspeaker company, the late Brian Cheney, came over to deliver them and set them up. The first thing he said to me when he saw my equipment was, "Ditch the preamp." I told him I needed it as a switch box to handle three separate CD players. He said, "OK," and never mentioned it again. That was over a dozen years ago.



More recently Classical Candor's Tech Analyst Bryan Geyer wrote an article called "On Controlling Volume" (https://classicalcandor.blogspot.com/2019/12/on-controlling-volume.html) in which he argued for replacing one's preamp with a passive volume control and input selector. He recommended the Goldpoint products and specifically the SA4. His reasoning made sense and reinforced what I had heard previously, so I tried it out. Why didn't I do this fifty years ago?



All right, then, why have most of us seen the necessity for a traditional preamp in the first place, and why is a passive preamp a better choice? Mostly, it turns out, the preamp has always been there for convenience. It provides not only a volume control but tone controls and switching capabilities for those who need them. More important, it provides additional amplification for components that may need an extra boost to their signal. This was especially important in the old days when everybody used a phonograph.



Now, what is the advantage of a passive preamp? First, let's clear up that name: "passive preamp" is really a misnomer since there is no amplification involved, "pre" or otherwise. The SA4 is more like a straight-wire bypass, taking a signal from your CD player directly to your amplifier. Perhaps "passive volume control" or "passive switch box" is more appropriate, even though the folks at Goldpoint prefer the term "passive preamp."



Anyway, the Goldpoint SA4 two-channel stereo "passive preamp" contains no actual electronic circuitry. It does not plug in. It is simply a volume control and switch box. With the SA4 you can hook up as many as four different components, switch among them, and control their volume. That's really all it does. Thus, you eliminate the need for a pre-amplifying stage and tone controls, thereby removing the added distortion that comes along with them.



Of course, if you don't care about the purity of the sound you're listening to, you're reading the wrong article. If you can't tell the difference between the sound of a well-mastered CD and an MP-3 file, the Goldpoint is probably not for you. The Goldpoint is for people who are trying to wring the last ounce of sonic quality from their system, getting the signal from the CD player to the amplifier with as few sonic impurities as possible. Ridding your system of preamp and tone-control distortions can do this. And at a much lower price than a good preamp would cost.



Next, how does the SA4 sound? Naturally, one would expect it to have no sound of its own. After all, it's not doing anything to the signal. Even if you have a ten-thousand dollar preamp, it's still got electronics in it that are producing distortion. At a twentieth that price, the SA4 has no distortion at all. Yes, I noticed the sonic differences almost immediately. Listening to discs I had heard repeatedly over the years, the clarity with the SA4 was most definitely improved. The dynamic impact and transient response were stronger. Even the breadth of the sound stage seemed widened. Bass resolution also appeared better focused and highs discernibly extended, with the volume control seeming to track left-right balance perfectly at any volume setting.

The SA4 in its natural environment

Mind you, these were not entirely night-and-day differences. We're not going from the sound of a windup Victrola to a contemporary surround-sound system here. My old preamp was about the best-sounding preamp I had owned over a fifty-plus year life in hi-fi, a period that included Pioneer, Soundcraftsmen, Audio Research, and Integra. But the differences were there and obvious to my ear. In other words, I couldn't be happier with the SA4.



Drawbacks? None sonically. It does exactly what it's supposed to do, no more, no less. All the same, it does not provide the convenience factors I mentioned earlier. If you positively have to have tone controls, distortion be hanged, you're out of luck with the SA4. And if you have a component with a very low signal, it may not be the best choice. (Here, Bryan assures me that most modern CD players have a high enough signal to feed the amplifier and most amps have enough gain to drive the speakers.* I have three CD players hooked up, and I've yet to take any of them past the one o'clock position on the SA4's volume control knob.) If in doubt, you might want to call Goldpoint (408-721-7102 or 408-737-3920). Another possible inconvenience is that unlike a lot of new preamps, there is no wireless remote involved. Get used to it.



The only other drawback I can think of is so small I hesitate even to mention it. When you eliminate all the electronic circuitry, you don't need a very big box to house what's left. The SA4 is relatively tiny (2.3" tall  x  4.7" wide  x  7.0" long) compared to a full-sized preamp. That means it's going to look awfully small and lonely on the shelf where your old preamp used to be. Seriously, though, it also means there is less room on the back of the unit for your various inputs and output. And less room means closer spacing of the gold-plated jacks. If you have big fingers, you may find it difficult to plug or unplug things.



Oh, and before I forget, Goldpoint offers their products in a variety of configurations. You can get volume controls in one-db or two-db stepped increments. You can get units that handle just one input and output or units that switch among two-to-four inputs. You can get units with one volume control for both channels or separate volume controls for left and right channels. You can get different input and output jacks and even different knobs. There is truly something at Goldpoint for everyone's passive preamp needs.



Finally, the cost of so small a unit may seem high ($532 for the SA4 as of this writing). However, the cost of the best materials are worth the price, and Goldpoint uses only the finest materials. Besides, when you consider how much better your system will sound and how much audiophile preamps cost, the price of the SA4 may seem like a bargain.



To see the full line of Goldpoint products, visit https://www.goldpt.com/



JJP (March 26, 2020)



*From "On Controlling Volume...," cited above: "Do confirm that you can drive your system to full output directly, without the need for supplementary preamp gain. In most cases this will be true, but exceptions happen; it’s dependent on your power amplifier’s internal voltage gain and on loudspeaker efficiency. Power amplifiers exhibit different internal voltage gains. Most designs range between +23dB and +29dB; refer spec. sheet, see “input sensitivity” (or equivalent term). Power amplifiers with gain = +29dB (e.g.: 1 Vrms input produces 100 Watts output [28.28 Vrms] across an 8Ω load) are inherently capable of reaching their full rated output capability when driven by virtually any modern line level program source. Power amplifiers with internal gain ≤ +24dB fall into an area that I consider marginal for use with a passive preamp when driving low efficiency mini-monitor speakers. Try to stick with amplifiers that provide ≥ +26dB gain."



Afterthought: I don't mean to imply by this review that everyone who buys an SA4 will like the sound of their system better than before. There is always the euphonious veiling effect of distortion to consider. That is, some people may have gotten used to the masking introduced by the distortion of their old equipment, a masking that, taken away, could reveal weaknesses in their speakers, amplifier, or CD player they hadn't noticed before.



I am reminded here of a subjective reviewer years ago who praised a particular phono cartridge as one of the best he had ever heard. Other reviewers noted that said cartridge had a pronounced peak in the top end, which they found objectionable. Later, the first reviewer revealed that the speakers he was using at the time of his listening tests had a roll-off at the high end that almost exactly matched the phono cartridge's peak. Thus, the deficiencies of the two components complemented one another and produced a euphonious sound.



Such is life; nothing is perfect, not even perfection. :)

Ecosse Maestro MA2 Interconnect Cables (Cable review)

Ecosse Reference Cables. The Stables@The Countryhouse, Kilmarnock, Scotland KA3 6EX (http://www.ecossecables.co.uk/)



By John J. Puccio



What? I hear you say: Why is Puccio reviewing a piece of hardware? And a controversial part of the hardware chain at that, a pair of interconnect cables. I thought he was a music-only man. Reasonable enough. But it is the hardware that allows us to hear the recording, so the equipment seems fair game. Besides, I decided it was time for a change, and what better a change than a pair of audio interconnect cables.



Again, I hear you asking: Why audio cables? I mean, everybody already knows that cables either (1) make all the difference in the world in the sound of a hi-fi system or (2) make no difference whatsoever. No, there aren't many people in the hi-fi or audiophile world who hold a neutral position on the topic. You're either in the cable camp or you're not; you either believe or you don't.



Let me tell you a brief story that may explain where I stand on the subject. A long time ago, maybe thirty years or more, an audiophile friend of mine decided to do a cable shoot-out at his house. He invited about a dozen of his audiophile buddies and me (I was never an audiophile; I couldn't afford it) to bring their favorite audio cables to a comparison test using his Sound Lab electrostatic speakers. He asked me to bring the cheapest pair of cables I could find so we'd have a solid contrast. I went to the nearest Radio Shack and bought a pair of their least expensive models, while the other guests brought some quite fancy (and quite expensive) stuff, including several people who owned their own cable companies, making and selling their own exotic products.



We spent the evening doing blind tests, writing notes, and not discussing anything until we had heard all the cables. Then we each rank ordered our picks, and my friend added up the scores. Remarkably, all of us at the event picked the same three cables as best; not in the same order, mind you, but the top three cables appeared on all of our lists as numbers one, two, or three. Just as remarkably, three more, different cables appeared at the bottom of everyone's list, one of the bottom three being the Radio Shack pair I had brought. It was also interesting that among the top three cables was a pair that a man had built himself by picking out a Belden cable on specs alone from a catalogue of about a million Belden cables. He fastened on two pair of gold ends that must have cost him ten times the price of the cable, and the result sounded so good that afterwards I made up a pair for myself and used them for years. (Later, moving my equipment to another cabinet necessitated longer cables, and by then I couldn't remember the Belden cable number or the name of the guy who built them, so I went with a good, popular cable brand of the day.)



Whatever, here's the thing: Some years after that, I wrote up the story of the shoot-out for a magazine I worked for at the time, telling the story pretty much as I explained it above. In the next issue, a colleague took me to task. The fellow writer said, basically, that all of us at the shoot-out were wrong, that we must have all been hallucinating, that there were absolutely no differences in the sound of one cable and another, that a cable was a cable, and that we were all hearing things. Yes, people get awfully worked up about interconnect cables, taking sides as though hi-fi were politics or religion. Or something really important like Star Wars movies.



Still, I heard what I heard that night, and so did twelve or so other people. As a result, I have tried to keep an open mind about the subject ever since. And, thus, we come to the present comparison, started more out of curiosity than anything else.



I decided after all these years to try out new connecting cables between my main CD player and my preamp. I wasn't about to attempt a full-blown cable shoot-out (which I would never have been able to do anyway, the logistics being darned near impossible). I just wanted to see if a modern interconnect of good repute would sound better than the good (and best-selling brand) I had used for years. I also realized there were hundreds of companies making "audiophile" cables, with each company making a host of different models. No shoot-out could possibly be comprehensive. So, I started by researching what other people knowledgeable on the subject had said, and found the Ecosse company of Scotland showing up strongly in various on-line comparison tests, as well as winning some major hi-fi awards. Since I had never heard of Ecosse before, I figured I would have no preconceptions about them. I contacted Elliot Davis, founder of Ecosse Cables, and he graciously agreed to send out a pair of his Maestro MA2's for listening.



Next, how to test them. The longer and best way to test any piece of new hardware is to install in your system and live with it for a week or two. Then take it back out and listen to your old component again. The quicker way, however, is to arrange an A-B test against your old equipment for instant comparison. I decided to do both.



Fortuitously, my main CD player, a Sony XA20ES, has two identical outputs. By connecting them to two different inputs on my preamp, I was able to use the preamp as a switch box for easy comparisons. Of course, I first had to make certain that both CD outputs were, indeed, identical. So, before connecting the Ecosse cables, I connected the second CD output to the preamp with a cable (that I had stored in the garage) exactly the same as the old one. Then I put on several recordings (including one of pink noise) and alternated between the two identical older cables, using a sound meter to be sure they were outputting the same volume and listening to be sure they sounded alike. Having satisfied myself that the two CD outputs were the same, I connected the new Ecosse cables next to my old ones and started the comparison. After an evening of A-B comparing using a variety of discs (and utilizing the talents of a very patient and understanding wife clicking back and forth at the preamp), I prepared for the long haul of listening to the Ecosse product by itself for a week or more.

Elliot Davis

Some of the discs I used during the testing included the classical: Debussy: Orchestral Music (Haitink, Concertgebouw Orchestra. Philips); Handel: Messiah (Ohrwall, Members of the Swedish Radio Symphony Orchestra. FIM/Proprius); Haydn: Baryton Divertimenti (The Esterhazy Machine. Smithsonian. FoM); Holst: The Planets (Previn, London Symphony Orchestra. Hi-Q Records/EMI); Mozart: Three Divertimenti for Strings (Marriner, Academy of St. Martin-in-the-Fields. FIM/Philips); Mozart: Violin Concertos Nos. 1, 2 & 4 (Mutter, LPO. JVC XRCD/DG); Rachmaninov: Symphonic Dances (Oue, Minnesota Orchestra. Reference Recordings); and Stravinsky: L'Histoire du Soldat (Ars Nova. HDTT/Westminster). Plus, an assortment of pop discs: Basie Jam (Analogue Productions gold/Pablo); Creedence Clearwater Chronicle (Fantasy gold); Jazz (Ry Cooder. Warner Bros.); Jazz at the Pawnshop (Arne Domnerus. FIM/Proprius); River Road (Eric Bibb and Bert Deivert, Opus 3); Slowhand (Eric Clapton. Mobile Fidelity gold/Polydor); Tango Tango (Viveza. Master Music XRCD); and Touch (John Klemmer. Mobile Fidelity gold/ABC/MCA).



Finally, to the point, how did the Ecosse cables sound compared to my old (and very popular) cables? In a word, better.



But I know what you want me to say, what you probably expect me to say: that it was an open-and-shut case, a matter of night and day. It wasn't. It was more like a matter of twilight and day. The differences were there for one to hear, but they were often subtle. Remember, I was comparing the Ecosse cables to a pair of very good cables; I wouldn't have lived with the old ones for as long as I did if they weren't pretty good.



With the Ecosse cables the width of the sound stage seemed about the same, yet there was a slightly greater sense of air around the instruments that made the recording hall or studio ambience all the more pronounced. Highs appeared a bit more extended with the Ecosse product, too, clearer and cleaner, with better sheen. Bass seemed almost the same, if a degree tauter, better defined, with the Ecosse product.



Midrange transparency was where I found differences most noticeable. Voices, for instance, sounded a degree better focused with the Ecosse cables, and all-around transparency was a tad more pleasing. The effect in listening to the old cables was something akin to putting one's hands lightly over one's ears. The differences were not dramatic, but they were discernible under almost all conditions and with almost every disc I put on. The battle for overall detail and clarity kept favoring the Ecosse product, my old cables sounding somewhat duller and more veiled by comparison. Differences in transient response and impact were harder to detect, though. Here, the slender variations I heard could have been the result of the Ecosse's better clarity. Who knows.



In all, the Ecosse Maestro MA2's seemed to do a better job than my old cables, producing a touch fuller, smoother, more lucid sound. Yet, as I say, it wasn't night-and-day for me, and without the benefit of the initial period of A-B testing, I'm not entirely sure I would have noticed the differences at all. Nor am I sure everyone would benefit from upgrading to Ecosse or any other new cables, depending on one's equipment, one's hearing, and one's interest in the whole subject.



Nevertheless, if you are still using the cheap cables that came with your system when you bought it, or if you're just of a mind to experiment, I doubt you could do any better than to try out one of Ecosse's full line of cables. Their prices start at the more-affordable level (under $100 a pair) and go up to over $2,000 a pair; you have a full slate to choose from. (The Maestros I sampled were a little over $200 a pair at the dealers I checked.)



Anyway, maybe Ecosse's Web site would provide better answers than I can give, and the site can also show you the differences among their various products: http://www.ecossecables.co.uk/



Happy listening.



JJP