試聴記事に用いたシステム ALTEC MILESTONE 604 S.M.S.L D-400EX audio research SP-8mk2
audio research D-115mk2 出力管のバイアスを再調整。
メーカーの推奨値は65mAとなっています。
以前は60mAと高めに設定していましたが。35mAでも問題なく
動作することが分かりましたので、大幅に電流値を少なく調整し直します。
メーカー規定バイアス値の場合では、真空管への負荷が大きい
レギュレーター管6550の故障はアンプに重大な損害を引き起こします。
早めの交換と真空管試験機を使った球の定期点検がお勧めです。
レギュレーター管の6550は長寿命で故障率が低いヴィンテージ管のNOS、
GE 6550のプレート電流値の低い物を選別して差し替えれば問題ないでしょう。
電源をOFFにしてから、ただ抜いて差し替えるだけで、事実上交換作業は問題はありません。
例えば一例を挙げると、こちらは弟機のaudio Research D-70の故障例ですが、
ツェーナーダイオード7本、抵抗1本、IC1本とかなり大規模に飛ばして
電源トランスのB電源の一番細くなっている線が黒くなって焦げて壊れてた、
このケースでは、スクリーングリッドに電力を供給している
レギュレーター管6550の故障だと思われます。
この球は消耗が激しく、規定バイアス値だと180～190℃まで熱くなる場合がある。
出力菅の故障はカソード抵抗を1～2個焼いてアンプが故障するので
早めの交換ができればお勧めですが、壊れた抵抗1～2個の交換とバイアス調整費用の
相場は約20,000円。出力菅のバイアス調整費のみだと15,000円くらいが相場ですので、
値段があまり変わりませんので、出力菅に関しては毎回ARCアンプが壊れるまで
使っても問題ありません。
ノイズやハムが出たらエアコンなど疑わしい家電製品の電源にノイズフィルタータップを
入れてみて下さい。真空管の劣化でノイズやハムが出たり増えた場合は自分で交換できます。
ハムの原因で最初に疑うべきはレギュレーター管の不良ですので、まず最初に交換してみる。
MT（ミニチュア）管の交換は、東欧や中国やロシア球でもいいので、
選別された特性値の優れたNOS球をショップに依頼して購入後に差し替えていくだけである。
使い手がこれらの注意点をよく心得ていれば、ARCアンプは無音で安定動作する。
パワーアンプの電源はオーソドックスに壁コン直取りとして、ハムが出る場合は
3Pインレットにグラウンドリフターを装着してアースを浮かせるなどの対策で改善される場合があります。
audio research D-70も所有していますが、そちらはプッシュプルなのでパワー値が低く、
ハイパワーなアメリカ製ARCアンプとしては初めて音が歪（ひず）んでしまったので、
50mAと少し高めに電流値を調整しています。
D-115はパラプッシュでパワーがありますから60mAから35mAに再調整することにしました。
なんと スクリーンに電力を供給しているレギュレーター管の6550は180〜190度から
90度まで下がりました。出力菅も130〜140度から80〜90度まで下がりました。
全面がパンチングメタルのボンネットで覆われていますが、
天面にPC用 USBファンを乗せて強制空冷しており、USB電源で電力供給しています。
audio research D-115mkII vacuum tube stereo power amplifier 1984 United States $3,250
The sound quality has a transparent tone with a firm attack (contour),
Although it is a tube unit, it can be regarded as a pioneer of high-end amplifiers.
The temperature is rather low, and the tone is clean, clear and thin,
It has a modern, hi-fi tone, and tends to be close to that of high-speed transistor amplifiers.
The sound overhang is quite intense, and the sound quality is somewhat dry and tense.
The ARC shows good suitability for reproducing house sounds and EDM club music.
It has a very gorgeous, inspiring sound, and the ARC amplifiers are generation after generation.
In the high and low frequencies, though, they approach the sound of transistor amplifiers,
the crucial midrange captures the core of the tube sound well.
It's as if the designer's passion for audio and music has been transferred,
The circuit configuration is elaborate and euphemistically extremely complex, and the number of components is unusually high,
The newly designed wideband transformer is a quantum leap from the previous generation's model,
It has been reborn with a crisper, more accurate sound quality, with no slack and a definite improvement in performance.
On the other hand, the CLASSIC SERIES, the successor to the D-115mkII, is too analytical,
The D SERIES of the early 1980s represents the peak era of the ARC,
ARC products born in the early 1980s were
ARC products from the early 1980s were the 'best' and 'pinnacle' of all audio products of the era.
They were more sophisticated and dignified, and their ability to portray reality was greatly enhanced,
It is on a different level from the others. No other product has been produced to date that surpasses it.
The evaluation is based on sound quality and artistry (timbre),
The evaluation axis is based on musicality. Once you hear the sound, you will be convinced that it is the best amplifier ever made,
Once you hear it, you will be convinced that it is the best amplifier ever made.
The audio research SP-10 SP-8 is the only preamplifier that should be combined with the D-115mkII.
The D-115mkII is not recommended for use with speakers from the 1950s.
The D-115mk II is not recommended for use with the ALTEC 604C from 1953, as the sound is too new,
The ALTEC 1520T, also from 1953, is a better match for the 1953 ALTEC 604C,
The temperature is much higher in comparison,
The temperature of the Altek 604C is much higher than that of the Altek 1520T, which is also from 1953, and has a richer listening experience with more sparkle.
In audio, it is important to match the age of the amplifier and speakers,
This is one of the theories that tend to produce good results.
The audio research D-115mkII is a fairly modern sounding amp compared to older vintage tube amps.
The D-115mkII is a fairly modern sounding amp compared to older vintage tube amplifiers, but with units developed in the 1980s, the D-115mkII is a good choice.
The ALTEC 604-8K, which uses a unit developed in the 1980s, gave very good results, but the D-115mkII's sound was not as good as the ALTEC 604-8K.
However, when played through the latest high-resolution speakers, the ALTEC did not have any of the roughness or range that was present in the ALTEC.
However, when playing the latest high-resolution speakers using a new material diaphragm, the sound was rough, and the range and resolution were not as good as those of modern amplifiers.
The sound was not as coarse as with the ALTEC, and the range and resolution were not as good as those of modern amplifiers.
System used in the article ALTEC MILESTONE 604 S.M.S.L D-400EX audio research SP-8mk2
audio research D-115mk2 output tube bias readjusted.
The manufacturer's recommendation is 65mA.
Previously, it was set at 60mA and higher, but we found that it works fine at 35mA.
So I readjusted the current value to a much lower value.
With the manufacturer's recommended bias value, the 6550 regulator tube, which places a heavy load on the bulb
Failure of regulator tube 6550, which places a heavy load on the bulb at the manufacturer's specified bias value, can cause serious damage to the amplifier.
Periodic inspections are recommended. Regulator tube 6550 has a long life and low failure rate.
Select a vintage NOS tube with a low plate current value of GE 6550 and replace it with a vintage NOS tube with a low plate current value of GE 6550.
If you replace it, there will be no problem. After turning off the power supply,
Just pull it out and replace it, and there is virtually no problem.
For example, here is an example of a faulty Audio Research D-70,
It has seven Zener diodes, one resistor and one IC.
The thinnest wire on the B power supply of the power transformer was blackened, burnt and broken,
In this case, supplying power to the screen grid
It is thought that the regulator tube 6550 is faulty.
This bulb wears out rapidly and can get as hot as 180-190°C at the specified bias value.
Failure of the output tube will burn out one or two cathode resistors and the amplifier will fail.
It is recommended to replace this as soon as possible, but the cost of replacing two resistors and adjusting the bias is
The market price is 20,000 yen. If it is only the bias adjustment cost of the output Kan, the market price is about 15,000 yen,
Since the price does not change much, there is no problem even if it uses it until it breaks every time about the output tube.
If noise or hum is generated, try inserting a noise filter tap into the power supply of suspect home appliances such as air conditioners.
If noise or hum is generated, try inserting a noise filter tap into the power supply of the suspected home appliance such as an air conditioner. If noise or hum appears or increases due to tube deterioration, you can replace the tubes yourself.
The first thing to suspect as the cause of hum is a defective regulator tube, so replace it first.
MT (miniature) tubes can be replaced with Russian, Eastern European or Chinese bulbs,
Simply ask the shop for a selected NOS bulb with good characteristic values and buy it and replace it.
The power supply for the power amplifier is orthodox, with a direct connection to the wall socket, and if hum is generated, use a
If hum is produced, it may be improved by installing a ground lifter on the 3P inlet to float the earth.
I also own an audio research D-70, but its power value is low because it is a push-pull,
I have also owned an audio research D-70, but its power value is low because it is a push-pull amplifier, and the sound was distorted for the first time as a high-power American-made ARC amplifier,
I adjusted the current value to 50mA, which is a little high.
The D-115 has power at para-push, so I decided to readjust it from 60mA to 35mA.
Oh my God, the 6550 regulator tube supplying power to the screen went from 180-190 degrees to
It dropped to 90 degrees. The output tube also dropped from 130-140 degrees to 80-90 degrees.
All sides are covered by a perforated metal bonnet, though,
A USB fan is placed on the top surface for forced air cooling and power is supplied by a USB power supply.
avant-garde UNO fino edition AIR-TIGHT ATM-300R audio research SP-8 (MM)
ALTEC 604C ALTEC 1520T audio research SP-8 (MM)
Introduction to analogue TRANSROTOR ZET1
It's long overdue, but I've finally started playing analogue records.
The turntable is a German TRANSROTOR ZET1.
Tone arm: SME 3009/Series II Improved (UK)
Cartridge: SHURE V15 Type IV, USA (I heard that Type III has a better reputation in Japan)
Tone arm cable: Japan EO by OYAIDE Elec d+ RCA for TurnTable class B
This cable is inexpensive, has good sound quality and is highly recommended.
The assembly method of ZET3 was published in the separate volume 'Analogue Bible' of SS magazine, so I assembled the turntable with reference to it.
I assembled the turntable referring to it.
SME 3009 seriesII Improved tone arm The earth terminal connection is here.
SME 3009 seriesII Improved Installation is done with a 2.0 mm Allen screwdriver.
If the Transrotor is not purchased with the optional base, the tone arm is SME-specific.
Adjust the height of the SME 3009/Series II Improved. If you don't adjust it perfectly.
If you do not adjust it perfectly, the body of the cartridge may rub the surface of the record.
Use a 1/16 size hexagonal spanner driver (the spanner set is 1/16, which is quite small,
It is not recommended to use a 1/16 size Allen screwdriver (the wrench set is quite small for a 1/16, so it is difficult to transmit force, making the work considerably more difficult).
Adjust the height of the black pillar (main pillar) in the centre by loosening the two bolts at the top and bottom.
It may take some getting used to, but you may need to use a light to get it inserted properly.
SME 3009/Series II Improved overhang adjustment. There are two knobs on each side.
Loosen the large silver knobs to adjust the front and rear position of the tone arm.
From the arm pipe of the tone arm to the centre shaft of the turntable.
Adjust the distance to 217.9 mm. Without this adjustment, the SME 3009 S2 imp
With the combination of a short arm and a lightweight Shure needle, the record will read well on the outer circumference of the record.
The record can be read well at the outer circumference, but as it gets closer to the inner circumference, trace errors occur and the record cannot be read correctly.
The long arm is also a good choice in terms of sound quality and readability. The long arm is advantageous both in terms of sound quality and reading ability.
The long arm has an advantage both in terms of sound quality and reading ability.
A large aluminium mirror-finished knob on the foot can be held by hand and turned left or right.
The height of the foot goes up and down and the turntable can be levelled.
Level the turntable precisely using the DAISO leveler.
Needle pressure was adjusted using the rider weight for needle pressure marking in the centre of the image.
Adjust the SHURE V15 Type IV to the optimum needle pressure. Needle pressure 0.75 - 1.25 g (optimum 1.0 g)
Use a needle pressure gauge (shinatsukei) to adjust to the optimum value of 1.0 g. If you weigh the needle pressure to about 1.2 g
This will reduce the risk of tracing errors and improve the sound. The tip of the needle should be
The tip of the needle must be accurately placed on the black dot in the centre of the needle pressure gauge, otherwise the correct value cannot be measured.
A record cleaner/brush is essential to reduce scratch noise and chatter.
The built-in phono equaliser of the audio research SP-8 (MM) was used as the phono equaliser.
The sound that emerges is a so-called 'Sure Tone', which is generally gentle and mild.
The sound is balanced between smooth highs and volume-rich bass,
The beauty of the piano sound and the expressive power of the vocals were so warm and mellow that I thought it was a sound that could never be produced digitally.
The beauty of the piano sound and the beautiful expression of the vocals could never be produced digitally.
As for sound preferences, for those who like vintage tube amplifiers and tube amplifiers with a deep listening experience, analogue vinyl is definitely not for you.
I would definitely recommend analogue vinyl to people who like vintage tube amps and deep listening tube amps.
If you ask the owner of a vintage shop, he will tell you that he has heard of vintage amps like the Mcintosh C22, Marantz7 and
ARC SP-8, and who prefer to use vintage tube preamplifiers like the Mcintosh C22, Marantz7 or ARC SP-8,
They said that not a single person uses an external phono equaliser.
With the MC cartridge DENON DL-103,
MC cartridge using a DENON or Peerless step-up transformer.
There is also a way to enjoy the high characteristic sound of MC cartridges using a DENON or Peerless step-up transformer. Actually, it seems to be dedicated to lightweight needles.
The DL-103 can be used with the SME 3009 S2 imp without any problems.
In this case, using a modern high characterisation phono equaliser such as Phasemation
They are also good to input on line.
An audition and technical description of SME and other tone arms can be found in KANEKYU OHKOKU Vol.59.
Kankyu Kingdom Vol.79 has another listening article on SME and other tone arms and cartridges with the same project.
The seemingly stainless steel finish of the Transrotor turntable.
The beautiful, shiny silver appearance is in fact an all-aluminium mirror finish.
It is said that the beautiful appearance of aluminium can be maintained indefinitely by polishing with SAN-A-Pearl or similar products.
The beauty of the external appearance of audio equipment is also important, and even when not playing sound, it can be enjoyed like a work of art to be looked at.
Like a work of art to be looked at and enjoyed, beautiful audio equipment enriches the owner's life.
The black base part of the ZET1 and ZET3 is said to be a synthetic material made from a mixture of sound-enhancing acrylic and carbon.
It has a hard resin-like texture to the touch.
The sound of the Transrotor turntable is exceptionally rich in overtones (resonance),
The texture is warm-toned and milder than it appears.
The grand scale orchestra sounded lush and fresh.
Equipment used for listening.
avant-garde UNO fino edition AIR-TIGHT ATM-300R audio research SP-8 (MM)
audio research SP-3 vacuum tube preamplifier 1973 United States $500？？
Towards the end of the 1960s, transistors, with their lower cost and higher versatility
began to emerge and vacuum tubes gradually disappeared from audio equipment.
Some music lovers were concerned that the industry was heading in the wrong direction.
Transistors were superior to tubes in terms of size and thermal dissipation, though,
musical performance was not far behind that of vacuum tubes.
Another transistor sceptic was a man named William Zane Johnson.
Bill was born in 1926 and designed his first tube amplifier at the age of 23,
In the decade from the age of 24, he was a living example of the glorious US tube golden age of the 1950s.
Bill owned and operated an audio specialty shop in south Minneapolis, Minnesota, USA,
He started his own shop, Electronic Industries, in 1952.
He sold and repaired TV's and hi-fi's, and since then Bill has been selling and repairing them for the people around him.
designed sophisticated custom amplifiers for the people around him. Amplifier designer.
After working as an amplifier designer, he finally started his own company, Audio Research Corporation, in 1970 with a group of former Marantz tube technicians.
He founded his own company, Audio Research Corporation (ARC), in 1970 with a group of former Marantz tube engineers.
audio research Successes include 'The Absolute Sound' and 'Stereophile',
by some of the most influential audio magazines of the time,
by the fact that it was declared the official benchmark for sound.
Audio Research now produces high-end audio products,
Audio Research is now the oldest surviving manufacturer of high-end audio products and is credited with giving birth to the very concept of high-end audio.
Audio Research is now considered to be the oldest surviving manufacturer of high-end audio products and is credited with giving birth to the very concept of high-end audio. Its first product, the SP-3 High-Definition
preamplifier, has sold thousands of units and has long been considered the best preamplifier on the market.
ARC's sound policy is a fusion of art and science, designed to take the art of reproduction to the extreme.
The sound of the SP-3 is an expression of a majestic heavenly world, with gorgeous echoes, strong brilliance and shimmering
The sound is scattered with an orgy of light. The sound is warm and stable.
AUDIO RESEARCH is a tube amp with a strong tube taste in the deep listening
category, it stands out from the crowd. In a word, it is "a sound of a different dimension".
It is truly a star of the first magnitude, a lone star that shines extraordinarily high. Gorgeous brilliance and sparkle.
As you immerse yourself in the dreamy, luxurious and gorgeous world of the ARC, you will unintentionally lose track of time.
The SP-3's sound is a little flat, with a tendency to capture music in broad strokes,
The SP-3's sound is a little flat, and it can be perceived as taking a broad view of the music and painting it in a straightforward manner, although the sound grain is a little coarse when you listen to it carefully,
However, this rough touch can also be felt as a proportionate boldness, and if the speakers to be paired with are examined carefully, negative impressions can be made.
If the speakers to be paired with are carefully considered, the impression will not be negative.
It is clear that the SP-3 is the most individual and strongly coloured preamplifier in the ARC preamplifiers of the past.
It has a soft sound that lets you fully enjoy its tube character, and for its age, it has sufficient resolution and softness.
The sound is soft and tube-like, with sufficient resolution and soft focus, but the essential sound contours are well-defined and thick.
It has a soft focus, but the essential sound contour is drawn with a firm, thick line, and although it is limited to low volume, it is pleasant to the ear and does not produce an irritating sound.
It has a feeling of not producing an irritating sound, and is a good choice for those who like tube amplifiers.
The sound is welcomed by many people who like tube amplifiers, as there are many who prefer this kind of sound.
The sound quality tendency is almost the same as that of the later SP-6 and SP-8, but the SP-3 is 10 years older,
The SP-3 is ten years older, so the resolution is lower, but the sound is more powerful and you can feel the strength of the sound as if you are being overpowered.
If you turn up the volume considerably, well, it may sound contradictory to what I have just said,
If you listen to ALTECs at near the volume as I do, the high frequencies seem to become harsher than those of the SP-8s.
This is the charm of the thick American sound of the rough-hewn sound. Pros of the SP-8 are that it can be used as an amplifier.
The advantage is that the sound does not break down even when the power of the amplifier is increased and louder, which is often the case.
The sound image does not collapse due to insufficient current supply, which is often the case with amplifiers, and the sound does not become noisy or distorted,
It is designed and engineered so that the sound is pleasant to listen to.
It is truly an amplifier for Americans who play loud.
The SP-8 is a normal evolution in terms of characteristics, with improved reality and more refinement,
You can choose the model you like after listening to the sound. Just a fierce sense of power and ARC sound.
The SP-3 is probably the best in terms of intense power and the strong appeal of the ARC sound. As for the power amplifier to be used with the SP-3, audio research is naturally the best choice.
Naturally, audio research is the best choice, followed by ALTEC, and for speakers, ALTEC or JBL.
The compatibility with ALTEC and JBL speakers was outstanding. After all, ALTEC and JBL speakers are the best,
TANNOY and Electro-Voice, but the ALTEC and JBL speakers were more suited to this amplifier, and could catch the overflowing energy.
The volume gain is not too high and it is easy to use.
The volume gain is not high and easy to use. The equaliser is also
It would be better not to use it on this amp, as the sound quality would deteriorate.
Vacuum tube 12AX7 x 8 W397 x H1140 x D318mm 6.3kg 50Hz/60Hz Power consumption 60W
All tubes in SP-3 are 12AX7/ECC83. Looking from the front panel side.
Three of the five MT tubes on the left are line tubes, two on the right are phono tubes.
The three tubes on the right across the divider are the equaliser tubes.
The old ARC preamplifiers were quite special and very sensitive to the vacuum tubes,
5751 (60% amplification), a highly reliable tube for the 12AX7 (80% amplification)
The Russian 12AX7 in the Murrard reissue did not produce any sound.
The author used Amperex RCA GE SILVANIA TELEFUNKEN SIEMENS
and other 12AX7s to confirm the normal operation of the SP-3.
All SP-3 tubes are 12AX7/ECC83. Looking from the front panel side.
The three MT tubes on the left side of the line of five are line tubes, the two on the right side are phono tubes
The three tubes on the right across the divider are the equaliser tubes.
The old ARC preamplifiers were quite special and very sensitive to the vacuum tubes,
5751 (60% amplification), a highly reliable tube for the 12AX7 (80% amplification)
The Russian 12AX7 in the Murrard reissue did not produce any sound.
The author used Amperex RCA GE SILVANIA TELEFUNKEN SIEMENS
and other 12AX7s, and confirmed the normal operation of the SP-3.
AUDIO RESEARCH The SP-3 is a world-class artist,
The SP-3 is also widely known as the favourite of world-renowned artist Eric Clapton, who used it for many years with a special fondness for it.
Equipment combined in listening ALTEC LANSING 604C Milestone 604 ALTEC 1520 audio research D-90B D-115
