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Customised or correct?
The fascination with single-ended and horns.
By John Paul
November 2000
What
this whole thing is about is making it sing a sweet song. It is all about
gratification through our inner notion of what that special "magic"
in the tune does for us.
True hi-fi hobbyists interests are poignantly addressed in my favourite
bit of kitchen embroidery wisdom that says, "For heights and depths
no words can reach, music is the souls' own speech".
This splendid "soul-speak" often brought to us by our specialised
reproduction equipment is now becoming more idiosyncratic. No longer do
all engineering "experts" argue "all amps measure, therefore
sound alike". Or can speakers makers tout the flatness of their irrelevant
lab curves.
"New" retro favours the form of lower power ancient style valve
amplification matched to efficient horn loaded loudspeakers. Fancied components
eschew accuracy in favour of sonic ecstasy. The ideal amp as "a straight
wire with gain" is being nudged by "a bent wire with no gain"!
Sussing Rumours
I've recently had the opportunity to hear both single ended and triode
push-pull type valve amplifier designs with some upgraded rear loaded
horn enclosure loudspeakers. And those rumours and opinion you may have
heard about them are true.
They are coloured, resonant and quirky from the start. But they are also
lively, exciting and quite enjoyable at the delivery end. The ideal pleasure
partner? You bet. Expensive, exotic, temperamental, but "oh, so nice,
when they're right!"
This
infatuation is chock full of contradictions such as a single-ended type
amplifier design has very few active components so there is actually less
interference with the signal. Good. But that signal also goes through
hundreds of metres of transformer wire where it gets the old inductive
volts to current massage with some unwanted resistance and capacitance
thrown in for bad measure. Many loudspeakers behave erratically, not erotically
to this characteristic.
And that very simplicity of single-ended valve amp design results in
power levels of less than ten real watts into a normal speaker load. Distortion
measurements can very quickly reach double digits, though the most critical
first watt is near perfect. But they frankly can be very nice to listen
to over highly efficient speakers. You may even say seductively sweet.
The horn loaded efficient speakers have some audible box flaws, but they
also have a very dynamic, immediate and revealing musical voice. Their
lightweight "secret" paper cones originate music as un-cloaked,
detailed and delicious in all it's naked glory. Happy without bland smoothing
crossovers, bextrene mush or quacky polypropylene cones.
Glancing Back
Let's delve further into this audio "earotica". David Manley,
founder of VTL (Vacuum Tube Logic), in his excellent book about valve
amplification argues that the transistor was originally adopted by nearly
all manufacturers exclusively on the basis of price. Quality transformers
which are necessary in any proper valve amp are simply quite expensive.
Therefore the tranny designs which do not need transformers and provide
more watts must be better. Not.
Marketing promises bent sonic reality. As many of us clumsily converted
from valve mono to tranny stereo we worried about ping-pong separation
(and later imaging) which somewhat obscures the fairly wretched hard,
grainy, fizzy and un-musical earlier tranny designs. Early hell, I think
the recent Pioneer A-400 and its' ilk are still plain tranny awful!
A few smart blokes hung on to their old Leak, Quad, McIntosh, Radford
or Dynaco valve amps and were completely happy to let "progress"
pass them by. Thirty or so years later better transistor amps are finally
becoming true to the music.
Horn speakers endured a similar economic squeeze, or should that be '80's
speak, "downsizing" back in the late fifties when stereo hit
and "whoops, you can't fit two of those here". Problem is downsizing
can't work in physics. Those acoustic laws don't bend in spite of glib
marketing claims. King horn maker Paul Klipsch was right in fighting the
very inefficient acoustic suspension designs then driven by some dubious
medium power transistor amplification. Acoustic suspension, or latter
fancy tuned venting, really requires big clean multi-kilowatts for fidelity
with sonic impact that's comparable to a proper horn system. Witness the
Cello Reference System.
The most efficient way to effectively excite air as sound is through
an acoustic impedance convertor (horn). Witness the power of brass instruments
and their respective ranges and size. The typical tuba has over a five
metre length air path to more effectively produce notes as low as we frequently
hear from string (double) or electric bass instruments.
Folding the horn around and around works, but it's very expensive because
you have to be extremely careful that the folding process doesn't introduce
extra tonal characteristics whereby your Fender bass guitar develops interesting,
but decidedly naff tuba-like voicing. Executed improperly and everybody,
say Van Morrison, Bobby McFerrin, Placido and pals, all can start sounding
like Edith Piaf through a bad car speaker in a large reverberant room.
Don't imagine it!
So building a high quality folded, re-entrant, or straight horn (around
8 metres path for an honest 40Hz), is inevitably an expensive and complicated
job.
Inventive Fantasy
"I have a cunning plan Lord Blackadder," said the malodorous
Baldrick. "Instead of making horn loudspeaker enclosures out of stiff
customwood sections, why don't we try modern extruded foam laminates and
carbon things similar to those used in chilly bins or racing boats to
develop that ever widening acoustic horn labyrinth. It'll be low resonance,
low weight and low in cost too, m'Lord."
Lord Blackadder disgustingly sneers, "Scum! One full-on fart from
your
bean-saturated bottom would blow the lightweight contraption clear across
the castle and destroy my precious soundstage!". The fragrant one
then replied, "But we can spike them sir." Whereupon his lordship
grimly grins then enthusiastically commands, "By Jesus, Baldrick,
bring me a big hammer and some large nails r-r-right now!". (With
nicest apologies to Ben Elton.)
Of course they are now making some smaller "designer" speaker
enclosures out of plastic type composites and they do seem to be much
lower in boxy colourations. So maybe the idea isn't a complete stinker.
In spite of that ostensible conceptualiser. Maybe this winter, I can…
Customising Fun
This retro appreciation is probably the best thing that's happened to
audio since diamond stylii. It's certainly got people listening now for
the true dynamic liveliness and clarity of music rather than just the
modern smooth response and bland low distortion detailed boredom that's
so easily attained with ordinary solid state and direct radiating drivers
in computer optimised boxes.
The "sweetness" of valve amps and the limits of perceived "benign"
distortion is basically a case of one man's trash is anothers treasure.
Do you really care if a Baldwin sounds like a Yamaha or a Steinway grand
piano as long as it's played well? And likely enough, the recording microphones
changed the tonal colour anyway. Or the producer or engineer goosed the
tone controls on the desk to "fix it up" as heard over their
"accurate" studio monitors.
Or at the end of the day, you just plain want "good enjoyable sound".
Screw accuracy! Ultimately it's "my money, my preferences".
My approach
I believe a systems subjective tonal accuracy is essential. Beyond toe-tapping
and scat singing along, I want to be able to instantly identify trumpeter
Kenny Wheeler from Woody Shaw. I like differentiating parentage of pianos,
and even (feebly) try to pick Zildjian from Paiste cymbals.
So I basically dislike owning any valve amps because of natural thermionic
deterioration characteristics. That is, the tubes do age and change with
time and so does the sound. And while source material is way too often
variable in particular sound qualities, I reject any system component
that has an intrinsically shifting sonic signature.
For some this moving distortion target is all part of the great fun in
trying different brands of valves and even different circuit configurations
with those same shifty bottles. So if you don't mind buying new tubes
to keep a certain sonic signature instead of buying silver or vinyl, it's
your money, your fun.
Investigating opinion
Playing around with valve amps and very efficient speakers is certainly
more fun and more rewarding than spending up large on relatively subtle
interconnect or speaker cable substitution experiments. With valves or
horns you won't strain to hear differences. You can easily hate them,
then love them. All in one stormy session.
If you know anyone or your favourite hi-fi shop has some fancy valve
amplification, try to arrange an extended audition. You will probably
be quite pleased at what comes through. Although beware of system matching
hassles. I once tried a pair of the respected VTL Tiny Triodes and, most
irritatingly, simply couldn't get rid of a loud mains hum. Hmmmm.
For listening to horn, or horn loaded enclosures for speakers it will
require more chasing because I can't think of any shop that currently
stocks any horns. The closest you can easily get are the half-horn concentrics
(woofer cone acting as the mid/high horn with bass from vented/bandpass
bottom) Tannoy or KEF units. These with their "highish" 1.7KHz
to 3.5KHz crossovers only suggest the energy and life a good horn system
can provide from the music. A biting brass trumpet edge, a good cymbal
crash, or a stirring triangle tingle can enticingly imply what could be
happening in full range via a proper horn loaded system.
So, can good horn loudspeakers with their full natural scale and effortless
dynamics get the concert and "whatever" else is part of the
performance into your living room? I'll tell you that with tight, smooth
amplification, some casual indifference to a recordings' anomalies, plus
a slight dose of relocation imagination, the big Klipschorns or Tannoy
Churchills can easily take you right there or bring it all on home. Listening
heaven.
The goal
I think any effort, multi-channel, digital enhancement, retro-tech, minimalist-purist,
video images, or whatever that leads to practically bringing the musicians
and vocalists smack-dab into our listening rooms is well worth the pursuit.
Include behaviour modifying chemicals for that reality enhancement too.
As widely mentioned, a good Burgundy can be a fine upgrade. Shame about
its in-system permanence though.
High Fidelity music reproduction is far beyond simple flat frequency
response and low distortion measurements. Music has subtle edges and resonances
and artifacts of its creation that help captivate our perception.
Any reproduction system that strives to capture all that literally could be stimulating our sensory mechanisms has to be headed in the right direction. There's also great fun in that chase too.
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