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| GW LABS 270 TUBE AMPLIFIER by Constantine Soo June 1, 2001 |
Specifications:
Type: Push-Pull
Power Output: 70W/channel RMS, 20 Hz-20 kHz 8 ohm
Frequency Response: 10 Hz – 80 kHz (THD+N: 0.65%/1 kHz/70W/8
Ohm)
Input Impedance: 150 kOhm
Input Sensitivity: 0.775V RMS / 1 kHz / 70W / 8 ohm
Tubes: 12AX7 × 2; 12AT7 × 2; SV6550C x 4
Power: 110-120 / 220-240 VAC, 50 / 60 Hz, 420W maximum
Dimensions: 15.5" (39.4cm) W × 7" (17.8cm) H × 14" (35.6cm) D
Weight: 31 lbs (14.1kg) net/ 35 lbs (15.9 kg) shipping
Warranty: 2 years limited parts and labor; 3 months on tubes
MSRP: $2,450.
CII Centasound International Inc.
PO Box 210377, San Francisco, CA 94121
Tel: 415.668.9003
Fax: 415.668.9638
Web: www.centasound.com
email: contact@centasound.com
Type: Push-Pull
Power Output: 70W/channel RMS, 20 Hz-20 kHz 8 ohm
Frequency Response: 10 Hz – 80 kHz (THD+N: 0.65%/1 kHz/70W/8
Ohm)
Input Impedance: 150 kOhm
Input Sensitivity: 0.775V RMS / 1 kHz / 70W / 8 ohm
Tubes: 12AX7 × 2; 12AT7 × 2; SV6550C x 4
Power: 110-120 / 220-240 VAC, 50 / 60 Hz, 420W maximum
Dimensions: 15.5" (39.4cm) W × 7" (17.8cm) H × 14" (35.6cm) D
Weight: 31 lbs (14.1kg) net/ 35 lbs (15.9 kg) shipping
Warranty: 2 years limited parts and labor; 3 months on tubes
MSRP: $2,450.
CII Centasound International Inc.
PO Box 210377, San Francisco, CA 94121
Tel: 415.668.9003
Fax: 415.668.9638
Web: www.centasound.com
email: contact@centasound.com
The proprietor and designer, Mr. Godfrey Wong, holds a law degree from
England and worked in the Hong Kong Finance sector before he came to the
U.S. Currently, he pursues other interests in the U.S., with high-end tube
amplifier design being one of them. There is a limited but growing number of
dealerships for his products. AudioGon, an internet store, handles the sales of
his Cyclops, a minuscule, zero-feedback, low-powered integrated amplifier.
Readers who live in areas with no GW Labs dealers may contact Mr. Wong
for direct orders. There is a 10-day return policy.
Mr. Wong looks at reliability as the most important design element of his
products. He believes that sound quality is of secondary importance to
reliability.
When I asked if GW Labs would make pure triode amplifiers, Mr. Wong
replied negatively. He considers the market for the limited output capability of
a pure triode amplifier too specialized. I agreed. I believe Mr. Wong would be
in a better position to address the particular needs of the "Triode Guild" once
his core business is well established.
Although I am not a feverish proponent of tube amplification, I do have a Music
Reference RM9 II of Ram Labs’ Roger Modjeski fame as my long-term
reference. An Audio Research D76a tube amplifier also served me well for
quite a while before I sold it for a Krell KST-100. Although I am using a pair of
the Monarchy Audio SM-70 as monoblocks in my system, the RM9 II remains
semi-active and is put to use whenever the need arises. It is the age-old
debate of tube vs. solid-state. Purveyors of each design’s state of the art offer
valid opinions regarding the beauties and strengths of either. However, since
the job of an amplifier is to amplify the incoming signal with maximum
integrity, in my opinion, progress will some day have the best from solid-state
and tubed amplification designs arriving at an impasse where either yields
the same sonic accomplishments.
THE AMPLIFIER
The GW Labs 270 chassis bears a striking resemblance to that of the
renowned Golden Tube Audio SE40. Having no affiliation with the husband
and wife team who owned and operated the Golden Tube Audio, GW Lab
contracted the shop that serviced GTA for its chassis design. This is where
the resemblance ends.
The GW Lab 270 sports two 6550 output tubes per channel. Two 12AX7s and
two 12AT7s act as driver tubes. Original product literature describes the 270
as running in triode for the input and ultra-linear push-pull for the output.
The front panel has only a rocker power switch, and the back panel provides
five-way binding posts for 0 (negative), 4 and 8 ohms impedance connection.
Only RCA inputs are provided. The power cord is detachable. As of this
writing, a cage is not available as an option.
This amplifier features a soft-start process, during which initial power-on
heats the filaments without powering up the tubes in the first 45-55 seconds.
According to Mr. Wong, this prevents electrical jolts, which would curtail the
tubes’ useful lives. I enjoyed watching the 270 switch over from soft-start to full
power, the output tubes changing from amber at soft-start to amber with blue.
Other interesting features include two "double C-core" output transformers, a
non-magnetic aluminum chassis, a .375-inch brushed and anodized aluminum
front panel, polypropylene coupling and bypass capacitors, and close
tolerance (1 & 2%) film resistors.
PRELIMINARY OUTLINE
Because of the even-order harmonic distortion tube amplifiers produce when
pushed hard – sonically less prominent than the odd-order distortions of
transistor amplifiers – one tube watt can sound as loud as two transistor watts.
The GW Labs 270 initially drove several pairs of loudspeakers for
comparison. Then I decided on concentrating this review on two: the Apogee
Duetta Signature and the Celestion SL700. These represent different levels of
inefficiency, the Apogee being the less efficient. This should provide the most
informative glimpse into the potential and shortcomings of the GW Labs 270.
I had developed a guilty conscience over my long-term loan of the GW Labs
270. My heartfelt thank-you goes to Mr. Godfrey Wong for his seemingly
endless patience. But did I have fun!
AUDITION 1: DRIVING THE CELESTION SL700
At 82dB/w/m and 8-ohm impedance, the inefficient Celestion SL700s require
a high-wattage amplifier to properly drive them. The Celestions are bi-wired.
When I purchased the Celestions in 1993, I used a Krell KST-100 power
amplifier with the KSL-2 line stage to drive them. Although this matching had
dynamic power, it was only marginally musical. The soundstaging was barely
perceptible; the sound, mechanical and edgy, at high volumes was almost
repellent. I replaced the Krell KST-100 with a Stereophile-recommended
Music Reference RM9 II. At an output of 125wpc, it utilized four EL34s for
each channel and three feedback settings. Running at the highest
output/lowest feedback setting, it brought out a new degree of transparency
and dimensionality to my SL700s. In addition, tonalities became more
discernible, with textural edginess largely eliminated.
The GW Labs 270, being a tube-based design as well, bears an audibly
different approach from ordinary tube amplification. It also runs much hotter
than the Music Reference RM9 II, despite its fewer tubes.
I played progressively louder until the Krell KRC-2’s volume control in high-
gain mode reached the 12 o’clock position. At that point, the dynamics and
loudness produced were among the most extreme I had ever heard from the
Celestions. The 270-driven Celestions actually played loud without strain. The
seemingly fragile, one-inch dome tweeter revealed every detail with volume to
spare.
Amplified by the 270, the towering dynamics and heart-stopping transients in
"A Night On the Bald Mountain" (The Stokowski Sound, Telarc CD-80129)
revealed an incisiveness not heard from the Music Reference RM9 II.
However, the RM9II made the strings sounded distinctively smoother and
airier, while the 270 offered added focus on individual instruments. The
sounding of the morning bell at the end of the track received a more lingering
treatment by the RM9 II over the 270 – well after the orchestra faded away.
Track 2, "Dies irae," of the Sony SACD Verdi Requiem (Sony SS 707)
captured the engulfing effect of hall ambience. The SACD’s superior
resolution enabled a bandwidth with information at both ends of the spectrum
in such abundance that, although systems with limited bandwidth may retain
their midrange prominence, they would seriously truncate the accompanying
dynamics and ambience. Devoid of compression and eerie sonic artifacts,
the 270-driven Celestions excited the air around them with definition and
upward extension.
At the bottom end, the 270 actually allowed the SL700 to sound more solid
than my 125-wpc Music Reference RM9 IIs. For a clearer perspective: the
Celestions’ 6.5-inch Cobex woofer is renowned for its macrodynamic
capability and punch. Spontaneous bursts of in-room energy in the low 50Hz
can be generated. In my audition, I would hesitate to claim a high 30-Hz
extension in the absence of actual on-site measurements of these mini-
monitors. However, the bass drum’s hellish strokes nearing the end of A Night
On the Bald Mountain unleashed the kind of bass response the Celestions
are not supposed to to attain.
To further illustrate the GW Labs’ power coupled to the Celestions: the "Dies
irae" from the same Sony SACD depicts Judgement Day in all its might. The
famous introductory bass-drum blows convey the fury and devastation of the
end of the world with destructive fury. It’s a wonder the drum actually survived
the performance. An overwhelming current of overtones further enhanced the
instrument’s realism. At an 11-o’clock volume setting, the immensity of the
power the SACD released, as empowered by a stable 270, almost pulverized
the 6.5inch Cobex cones.
In retrospect, the 6.5inch woofer could not roll out the undercurrents of full-
range systems, as evident in the synthesizer’s driving bottom octave in
"Incident at Isla Nablar" (Soundtrack of Jurassic Park MCAD-10859).
However, both quality and quantity of the Celestions’ bass in conjunction with
the 270 was consistently superior to that of my RM9 II. This level of
performance from the Celestion SL700 as enabled by the 270 was not only
surprising but also gratifying. Every time a pair of so-called mini-monitors
exhibits their ability to produce devastating dynamics, we know that the
audiophile doesn’t need a huge room in order to attain musical nirvana on a
realistic scale.
AUDITION 2: APOGEE DUETTA SIGNATURE
The next speakers I put the GW Labs through were the Apogee Duetta
Signatures. At 86dB/w measured at 3m distance, and with 4ohms average
impedance, the Apogees feature two 5-foot-tall panels, each containing large,
air-vibrating ribbon areas. Most Apogee users rely on high-current solid-state
amplifiers, like products from Krell, Aragon, Threshold and Forte, to name a
few, for providing adequate volume and driver control for their speakers. For
more information, check out the Apogee Speaker Users Website at http:
//www.apogeespeakers.totalserve.co.uk/.
The Duetta Signatures facilitates bi-wiring and bi-amping functions. Its own
passive crossovers cut off frequencies at 1000Hz. The terminal also allows
users to control the ribbon tweeter output at the levels of Low, Normal and
High. Driving the Apogees’ tweeters with different amplifiers revealed
interesting results.
I used an Aragon 2004 to drive the full-range Apogees to very high volumes
without audible distortions. The Aragon put out 200 wpc at 4 ohms, exerting
adequate control over the bass ribbons. The result is one of weight and
speed. The rather mild top end of the Aragon also nicely compliments the
Apogees’ high tweeter output setting. Imaging is acceptable in terms of
soundstage stability and width, but areas I find wanting are sharper images,
deeper soundstaging and richer ambience.
Despite the aforementioned Aragon shortcomings, the Apogees, with their
adult-height ribbons, nevertheless demonstrate themselves as soundstaging
champions, capable of three dimensionality surpassing even that of the
Celestion SL700. That dimensionality became more prominent when the GW
Labs 270 replaced the Aragon. In addition to tube amplifiers’ well-known
dimensionality capabilities, another contribution was the 270’s top-end
extension. Instrument placement was specific and well defined on the vertical
and horizontal planes.
By the same token, the high ribbon-tweeter setting sounded overly bright with
instruments like triangles and cymbals. Violins and brasses also exhibited an
extra degree of sharpness. Resetting the tweeter level to normal or
sometimes low alleviated the symptom. The setback was a loss of
soundstaging finesse. Even so, the Apogees still excelled in lateral and
horizontal soundstage portrayal.
Noteworthy again was the 270’s ability in bass control. The same cut from
Jurassic Park received a more thorough treatment. With the Apogees’ full-
range capability, the synthesizer’s bass notes were clear and full-bodied. The
Apogees, with their 30-Hz low end limit, sustained the rumbling notes. The
270 was surprising competent in energizing the ribbons at their bottom end.
The 270-driven Apogees also did well in the areas of mid-range transparency
and soundstaging. Image localization was impressively three dimensional for
most recordings. However, at screamingly realistic sound levels, noticeable
soundstage deterioration developed when relentless dynamic contents were
being fed. When playing the SACD track "Dies irae," the bass drum
information drained the resources of the 270, infecting the entire
performance. Not only did soundstaging suffer in terms of loss of definition,
instrument imaging smeared and macrodynamics compressed.
Substituting the GW Labs with the Music Reference mitigated the problem.
Though not as extended at the frequency extremes as the 270, the RM9 II
carried the performance through all challenges with ease. Power became the
key in this instance.
Another trade off: the Apogees’ imaging sounded closer when amplified by
the Music Reference, whereas the GW Labs took the listener a few rows
back. I prefer the GW Labs’ character because orchestral passages as
produced by the 270 sound more spectacular in my listening room. You may
opt for the proximity offered by the Music Reference and find it more
enjoyable. In fact, I believe my room may be too small to realize what a more
powerful combo like RM9 II and Apogees can do.
Apogee’s Website features users’ viewpoints and experiences in getting the
best out of these speakers. The forum’s most prevalent and admired
amplifiers are the Krells and Thresholds, high-power, high-current, microwave-
size amplifiers.
CONCLUSION
At an MSRP of $2,450, the GW Labs 270 should appeal to budget-minded
audiophiles.
The 270 has a cunning ability to drive less efficient speakers to very high
volumes before strain or distortions become obvious. Its unique, transistor-
like stability preserves the recorded frequency spectrum while its tubey heart
precludes transistor-like and ugly odd-order harmonic distortions.
The 270’s midrange reveals the purity one would expect from a tube design.
However, there isn’t a hint of the typically soft and tubey sound. In fact, the
amp sounds quite modern, with its extended frequency response and superb
analytical ability. Information like soundstaging, frequency extensions,
transient attacks are all produced with glory and flare at very high decibels. I
suspect the 270’s dual "double C-core" output transformers are the
contributing element in its ability to deliver full power at all frequencies. This
type of transformer ability in delivering perpetual, uncompressed power at
18kHz and above is vastly superior to the regular EI transformers, which run
out of power almost entirely at that range.
In the case of my Celestion SL700, the 270 was able to drive them to
extremely high sound pressure levels without strain. Remembering how the
solid-state Krell KST-100 fared in my system, I believe the GW Labs 270’s
fundamental tube design – in conjunction with the dual "double C-core" output
transformers – allowed the delivery of full power into inert loads, while
maintaining equal signal transparency throughout the frequency spectrum.
Given the performance of the GW Labs 270 in the company of my inefficient
Celestion SL700, I can imagine how more fantastic my Apogee Duetta
Signatures would sound like with two 270s bridged into monoblock
operations. My ongoing schedule prevented me from trying that; but I hope
there is a chance of doing this in the future.
Regarding monoblock configuration, the utilization of output transformers in
tube amplifiers enables reconfiguration by the user, to make two similar
amplifiers function as monoblocks. Contact Mr. Wong for easy user-friendly
configuration details.
The sonic signature of the original 6550 tubes may not appeal to all tastes.
Sonic characteristics will change considerably with compatible tubes, such as
KT-88 or KT-90. Seriously interested readers may also want to check out the
premium 6550 variety from a European maker named Electro-Harmonix.
The one important aspect of acquiring the GW Labs 270 is the means to
match it with a high-output preamplifier. This is particularly important if
inefficient speakers are to be driven. It was the high-gain mode of my Krell
KRC-2 that played a pivotal role in extracting the best out of my Celestion
SL700. Therefore, for the power of the 270 to be fully appreciated, a high-
output preamplifier is recommended.
Current owners of the Celestion SL700 and inefficient mini-monitors alike
should give the GW Labs 270 a try just to experience the extraordinary
dynamics and musicality accorded. For readers who have other kinds of
exotic, inefficient speakers, a pair of 270s will probably fall into your budget
for amplifiers. As monoblocks, the GW Labs 270s will drive some of the most
difficult loudspeakers to very realistic levels in the glories of tube purity and
spectral integrity.
Tube amplifiers have not been my usual preference for the most part – the
maintenance-free aspect of solid-state amplifiers holds a good chunk of my
votes of approval. However, Roger Modjeski’s Ram Labs Music Reference
RM9 II, and now Godfrey Wong’s GW Labs 270, proved their designers’
genius profoundly in both their asking price and the excellence of the
performance.
In my opinion, readers who favor jazz music will likely find the GW Labs 270’s
evenness of clean-cut precision instrumental in portraying an energetic
performance. Its orchestral music rendition is characterized by wide
bandwidth interpretation. The RM9 II’s orchestral music portrayal has more of
the tube’s emphasis in tonal beauty as opposed to the 270’s extended
bandwidth.
Ladies and gentlemen, this could be the beginning of a new generation of
"advanced" tube amplifiers.
My next review is on the diminutive Decware SE84C triode single-ended
class A tube amplifier. It will be interesting to see how the dominating
Klipschorns will sound as driven by this modest-looking design.
Associated Equipment:
Digital Front End
CEC TL1 CD transport
Sony SCD-777ES SACD/CD player
Wadia 27 Decoding Computer,
Amplification
Aragon 2004
Krell KRC-2
Decware SE84C
Monarchy Audio SM70 monoblocks
Music Reference RM9 II
Loudspeakers
Apogee Duetta Signature
Celestion SL700
Klipschorns
Cabling
Granite Audio# 470 as coaxial (1m)
Granite Audio #470 silver cables (unbalanced, 1m)
Cardas 5c (8 feet)
Van Den Hul MCD-352 (8 feet)
England and worked in the Hong Kong Finance sector before he came to the
U.S. Currently, he pursues other interests in the U.S., with high-end tube
amplifier design being one of them. There is a limited but growing number of
dealerships for his products. AudioGon, an internet store, handles the sales of
his Cyclops, a minuscule, zero-feedback, low-powered integrated amplifier.
Readers who live in areas with no GW Labs dealers may contact Mr. Wong
for direct orders. There is a 10-day return policy.
Mr. Wong looks at reliability as the most important design element of his
products. He believes that sound quality is of secondary importance to
reliability.
When I asked if GW Labs would make pure triode amplifiers, Mr. Wong
replied negatively. He considers the market for the limited output capability of
a pure triode amplifier too specialized. I agreed. I believe Mr. Wong would be
in a better position to address the particular needs of the "Triode Guild" once
his core business is well established.
Although I am not a feverish proponent of tube amplification, I do have a Music
Reference RM9 II of Ram Labs’ Roger Modjeski fame as my long-term
reference. An Audio Research D76a tube amplifier also served me well for
quite a while before I sold it for a Krell KST-100. Although I am using a pair of
the Monarchy Audio SM-70 as monoblocks in my system, the RM9 II remains
semi-active and is put to use whenever the need arises. It is the age-old
debate of tube vs. solid-state. Purveyors of each design’s state of the art offer
valid opinions regarding the beauties and strengths of either. However, since
the job of an amplifier is to amplify the incoming signal with maximum
integrity, in my opinion, progress will some day have the best from solid-state
and tubed amplification designs arriving at an impasse where either yields
the same sonic accomplishments.
THE AMPLIFIER
The GW Labs 270 chassis bears a striking resemblance to that of the
renowned Golden Tube Audio SE40. Having no affiliation with the husband
and wife team who owned and operated the Golden Tube Audio, GW Lab
contracted the shop that serviced GTA for its chassis design. This is where
the resemblance ends.
The GW Lab 270 sports two 6550 output tubes per channel. Two 12AX7s and
two 12AT7s act as driver tubes. Original product literature describes the 270
as running in triode for the input and ultra-linear push-pull for the output.
The front panel has only a rocker power switch, and the back panel provides
five-way binding posts for 0 (negative), 4 and 8 ohms impedance connection.
Only RCA inputs are provided. The power cord is detachable. As of this
writing, a cage is not available as an option.
This amplifier features a soft-start process, during which initial power-on
heats the filaments without powering up the tubes in the first 45-55 seconds.
According to Mr. Wong, this prevents electrical jolts, which would curtail the
tubes’ useful lives. I enjoyed watching the 270 switch over from soft-start to full
power, the output tubes changing from amber at soft-start to amber with blue.
Other interesting features include two "double C-core" output transformers, a
non-magnetic aluminum chassis, a .375-inch brushed and anodized aluminum
front panel, polypropylene coupling and bypass capacitors, and close
tolerance (1 & 2%) film resistors.
PRELIMINARY OUTLINE
Because of the even-order harmonic distortion tube amplifiers produce when
pushed hard – sonically less prominent than the odd-order distortions of
transistor amplifiers – one tube watt can sound as loud as two transistor watts.
The GW Labs 270 initially drove several pairs of loudspeakers for
comparison. Then I decided on concentrating this review on two: the Apogee
Duetta Signature and the Celestion SL700. These represent different levels of
inefficiency, the Apogee being the less efficient. This should provide the most
informative glimpse into the potential and shortcomings of the GW Labs 270.
I had developed a guilty conscience over my long-term loan of the GW Labs
270. My heartfelt thank-you goes to Mr. Godfrey Wong for his seemingly
endless patience. But did I have fun!
AUDITION 1: DRIVING THE CELESTION SL700
At 82dB/w/m and 8-ohm impedance, the inefficient Celestion SL700s require
a high-wattage amplifier to properly drive them. The Celestions are bi-wired.
When I purchased the Celestions in 1993, I used a Krell KST-100 power
amplifier with the KSL-2 line stage to drive them. Although this matching had
dynamic power, it was only marginally musical. The soundstaging was barely
perceptible; the sound, mechanical and edgy, at high volumes was almost
repellent. I replaced the Krell KST-100 with a Stereophile-recommended
Music Reference RM9 II. At an output of 125wpc, it utilized four EL34s for
each channel and three feedback settings. Running at the highest
output/lowest feedback setting, it brought out a new degree of transparency
and dimensionality to my SL700s. In addition, tonalities became more
discernible, with textural edginess largely eliminated.
The GW Labs 270, being a tube-based design as well, bears an audibly
different approach from ordinary tube amplification. It also runs much hotter
than the Music Reference RM9 II, despite its fewer tubes.
I played progressively louder until the Krell KRC-2’s volume control in high-
gain mode reached the 12 o’clock position. At that point, the dynamics and
loudness produced were among the most extreme I had ever heard from the
Celestions. The 270-driven Celestions actually played loud without strain. The
seemingly fragile, one-inch dome tweeter revealed every detail with volume to
spare.
Amplified by the 270, the towering dynamics and heart-stopping transients in
"A Night On the Bald Mountain" (The Stokowski Sound, Telarc CD-80129)
revealed an incisiveness not heard from the Music Reference RM9 II.
However, the RM9II made the strings sounded distinctively smoother and
airier, while the 270 offered added focus on individual instruments. The
sounding of the morning bell at the end of the track received a more lingering
treatment by the RM9 II over the 270 – well after the orchestra faded away.
Track 2, "Dies irae," of the Sony SACD Verdi Requiem (Sony SS 707)
captured the engulfing effect of hall ambience. The SACD’s superior
resolution enabled a bandwidth with information at both ends of the spectrum
in such abundance that, although systems with limited bandwidth may retain
their midrange prominence, they would seriously truncate the accompanying
dynamics and ambience. Devoid of compression and eerie sonic artifacts,
the 270-driven Celestions excited the air around them with definition and
upward extension.
At the bottom end, the 270 actually allowed the SL700 to sound more solid
than my 125-wpc Music Reference RM9 IIs. For a clearer perspective: the
Celestions’ 6.5-inch Cobex woofer is renowned for its macrodynamic
capability and punch. Spontaneous bursts of in-room energy in the low 50Hz
can be generated. In my audition, I would hesitate to claim a high 30-Hz
extension in the absence of actual on-site measurements of these mini-
monitors. However, the bass drum’s hellish strokes nearing the end of A Night
On the Bald Mountain unleashed the kind of bass response the Celestions
are not supposed to to attain.
To further illustrate the GW Labs’ power coupled to the Celestions: the "Dies
irae" from the same Sony SACD depicts Judgement Day in all its might. The
famous introductory bass-drum blows convey the fury and devastation of the
end of the world with destructive fury. It’s a wonder the drum actually survived
the performance. An overwhelming current of overtones further enhanced the
instrument’s realism. At an 11-o’clock volume setting, the immensity of the
power the SACD released, as empowered by a stable 270, almost pulverized
the 6.5inch Cobex cones.
In retrospect, the 6.5inch woofer could not roll out the undercurrents of full-
range systems, as evident in the synthesizer’s driving bottom octave in
"Incident at Isla Nablar" (Soundtrack of Jurassic Park MCAD-10859).
However, both quality and quantity of the Celestions’ bass in conjunction with
the 270 was consistently superior to that of my RM9 II. This level of
performance from the Celestion SL700 as enabled by the 270 was not only
surprising but also gratifying. Every time a pair of so-called mini-monitors
exhibits their ability to produce devastating dynamics, we know that the
audiophile doesn’t need a huge room in order to attain musical nirvana on a
realistic scale.
AUDITION 2: APOGEE DUETTA SIGNATURE
The next speakers I put the GW Labs through were the Apogee Duetta
Signatures. At 86dB/w measured at 3m distance, and with 4ohms average
impedance, the Apogees feature two 5-foot-tall panels, each containing large,
air-vibrating ribbon areas. Most Apogee users rely on high-current solid-state
amplifiers, like products from Krell, Aragon, Threshold and Forte, to name a
few, for providing adequate volume and driver control for their speakers. For
more information, check out the Apogee Speaker Users Website at http:
//www.apogeespeakers.totalserve.co.uk/.
The Duetta Signatures facilitates bi-wiring and bi-amping functions. Its own
passive crossovers cut off frequencies at 1000Hz. The terminal also allows
users to control the ribbon tweeter output at the levels of Low, Normal and
High. Driving the Apogees’ tweeters with different amplifiers revealed
interesting results.
I used an Aragon 2004 to drive the full-range Apogees to very high volumes
without audible distortions. The Aragon put out 200 wpc at 4 ohms, exerting
adequate control over the bass ribbons. The result is one of weight and
speed. The rather mild top end of the Aragon also nicely compliments the
Apogees’ high tweeter output setting. Imaging is acceptable in terms of
soundstage stability and width, but areas I find wanting are sharper images,
deeper soundstaging and richer ambience.
Despite the aforementioned Aragon shortcomings, the Apogees, with their
adult-height ribbons, nevertheless demonstrate themselves as soundstaging
champions, capable of three dimensionality surpassing even that of the
Celestion SL700. That dimensionality became more prominent when the GW
Labs 270 replaced the Aragon. In addition to tube amplifiers’ well-known
dimensionality capabilities, another contribution was the 270’s top-end
extension. Instrument placement was specific and well defined on the vertical
and horizontal planes.
By the same token, the high ribbon-tweeter setting sounded overly bright with
instruments like triangles and cymbals. Violins and brasses also exhibited an
extra degree of sharpness. Resetting the tweeter level to normal or
sometimes low alleviated the symptom. The setback was a loss of
soundstaging finesse. Even so, the Apogees still excelled in lateral and
horizontal soundstage portrayal.
Noteworthy again was the 270’s ability in bass control. The same cut from
Jurassic Park received a more thorough treatment. With the Apogees’ full-
range capability, the synthesizer’s bass notes were clear and full-bodied. The
Apogees, with their 30-Hz low end limit, sustained the rumbling notes. The
270 was surprising competent in energizing the ribbons at their bottom end.
The 270-driven Apogees also did well in the areas of mid-range transparency
and soundstaging. Image localization was impressively three dimensional for
most recordings. However, at screamingly realistic sound levels, noticeable
soundstage deterioration developed when relentless dynamic contents were
being fed. When playing the SACD track "Dies irae," the bass drum
information drained the resources of the 270, infecting the entire
performance. Not only did soundstaging suffer in terms of loss of definition,
instrument imaging smeared and macrodynamics compressed.
Substituting the GW Labs with the Music Reference mitigated the problem.
Though not as extended at the frequency extremes as the 270, the RM9 II
carried the performance through all challenges with ease. Power became the
key in this instance.
Another trade off: the Apogees’ imaging sounded closer when amplified by
the Music Reference, whereas the GW Labs took the listener a few rows
back. I prefer the GW Labs’ character because orchestral passages as
produced by the 270 sound more spectacular in my listening room. You may
opt for the proximity offered by the Music Reference and find it more
enjoyable. In fact, I believe my room may be too small to realize what a more
powerful combo like RM9 II and Apogees can do.
Apogee’s Website features users’ viewpoints and experiences in getting the
best out of these speakers. The forum’s most prevalent and admired
amplifiers are the Krells and Thresholds, high-power, high-current, microwave-
size amplifiers.
CONCLUSION
At an MSRP of $2,450, the GW Labs 270 should appeal to budget-minded
audiophiles.
The 270 has a cunning ability to drive less efficient speakers to very high
volumes before strain or distortions become obvious. Its unique, transistor-
like stability preserves the recorded frequency spectrum while its tubey heart
precludes transistor-like and ugly odd-order harmonic distortions.
The 270’s midrange reveals the purity one would expect from a tube design.
However, there isn’t a hint of the typically soft and tubey sound. In fact, the
amp sounds quite modern, with its extended frequency response and superb
analytical ability. Information like soundstaging, frequency extensions,
transient attacks are all produced with glory and flare at very high decibels. I
suspect the 270’s dual "double C-core" output transformers are the
contributing element in its ability to deliver full power at all frequencies. This
type of transformer ability in delivering perpetual, uncompressed power at
18kHz and above is vastly superior to the regular EI transformers, which run
out of power almost entirely at that range.
In the case of my Celestion SL700, the 270 was able to drive them to
extremely high sound pressure levels without strain. Remembering how the
solid-state Krell KST-100 fared in my system, I believe the GW Labs 270’s
fundamental tube design – in conjunction with the dual "double C-core" output
transformers – allowed the delivery of full power into inert loads, while
maintaining equal signal transparency throughout the frequency spectrum.
Given the performance of the GW Labs 270 in the company of my inefficient
Celestion SL700, I can imagine how more fantastic my Apogee Duetta
Signatures would sound like with two 270s bridged into monoblock
operations. My ongoing schedule prevented me from trying that; but I hope
there is a chance of doing this in the future.
Regarding monoblock configuration, the utilization of output transformers in
tube amplifiers enables reconfiguration by the user, to make two similar
amplifiers function as monoblocks. Contact Mr. Wong for easy user-friendly
configuration details.
The sonic signature of the original 6550 tubes may not appeal to all tastes.
Sonic characteristics will change considerably with compatible tubes, such as
KT-88 or KT-90. Seriously interested readers may also want to check out the
premium 6550 variety from a European maker named Electro-Harmonix.
The one important aspect of acquiring the GW Labs 270 is the means to
match it with a high-output preamplifier. This is particularly important if
inefficient speakers are to be driven. It was the high-gain mode of my Krell
KRC-2 that played a pivotal role in extracting the best out of my Celestion
SL700. Therefore, for the power of the 270 to be fully appreciated, a high-
output preamplifier is recommended.
Current owners of the Celestion SL700 and inefficient mini-monitors alike
should give the GW Labs 270 a try just to experience the extraordinary
dynamics and musicality accorded. For readers who have other kinds of
exotic, inefficient speakers, a pair of 270s will probably fall into your budget
for amplifiers. As monoblocks, the GW Labs 270s will drive some of the most
difficult loudspeakers to very realistic levels in the glories of tube purity and
spectral integrity.
Tube amplifiers have not been my usual preference for the most part – the
maintenance-free aspect of solid-state amplifiers holds a good chunk of my
votes of approval. However, Roger Modjeski’s Ram Labs Music Reference
RM9 II, and now Godfrey Wong’s GW Labs 270, proved their designers’
genius profoundly in both their asking price and the excellence of the
performance.
In my opinion, readers who favor jazz music will likely find the GW Labs 270’s
evenness of clean-cut precision instrumental in portraying an energetic
performance. Its orchestral music rendition is characterized by wide
bandwidth interpretation. The RM9 II’s orchestral music portrayal has more of
the tube’s emphasis in tonal beauty as opposed to the 270’s extended
bandwidth.
Ladies and gentlemen, this could be the beginning of a new generation of
"advanced" tube amplifiers.
My next review is on the diminutive Decware SE84C triode single-ended
class A tube amplifier. It will be interesting to see how the dominating
Klipschorns will sound as driven by this modest-looking design.
Associated Equipment:
Digital Front End
CEC TL1 CD transport
Sony SCD-777ES SACD/CD player
Wadia 27 Decoding Computer,
Amplification
Aragon 2004
Krell KRC-2
Decware SE84C
Monarchy Audio SM70 monoblocks
Music Reference RM9 II
Loudspeakers
Apogee Duetta Signature
Celestion SL700
Klipschorns
Cabling
Granite Audio# 470 as coaxial (1m)
Granite Audio #470 silver cables (unbalanced, 1m)
Cardas 5c (8 feet)
Van Den Hul MCD-352 (8 feet)