Audio Research D-90B Vacuum Tube Stereo Power Amplifier, 1981, USA This amplifier led experts to conclude that the use of such a large number of vacuum tubes and complex stacking of tubes was the only way to achieve such a captivating sound. This is one of the most important power amplifiers in Audio Research's 56-year history, and it remains popular in Europe, the United States, Australia, Taiwan, and Korea. In Japan, the then distributor, Phan Gati Industria, vigorously promoted it, but due to excessive margins and a very high price, while many audio retailers recommended it, sales numbers did not increase significantly. (Recently, older ARC amplifiers have become popular in emerging audio markets such as China, Vietnam, and Thailand.) In the United States, consumer-friendly business practices (laws) have long allowed new products to be returned within one month of purchase, provided they were in their original condition. Their top priority was to create a product with a pandering sound that would make buyers reluctant to return it, a product that consumers could actually hear and appreciate.As a result, even audio equipment from American companies that are well-known and popular in Japan often accounts for a large proportion of its sales overseas and is not sold in the United States. Despite this tough environment for retailers, and despite the fact that vacuum tube amplifiers are a minority, ARC enjoyed tremendous popularity and strong support, ranking number one in the United States. Its influence remains today, with countless ARC dealers around the world. The audio research D-90B's sound quality is heavenly, with a majestic, heavenly tone. It is bright, brilliant, gorgeous, and powerful, with a sweet tone and a kind of spectacular, extremely powerful sound, and has a very strong American entertainment flavor. ARC (audio research Corporation) amplifiers have an incredibly sweet, captivating tone compared to any other amplifiers. While the later Audio Research SP-11 generation ARCs from the mid-'80s are considered bright, bleached, and dry, the D-90B delivers a fresh, wet sound. For those familiar with Audio Research's sound, if you find a used one in good condition, it has an irresistible sound that makes it a snap to buy. Compared to the D-70, with a 6550 push-pull amplifier weighing 22.8kg, this model is a parallel push-pull amplifier weighing 29kg, the scale of playback, overwhelming bass power, and energy are quite different. All output tubes have been replaced with new Philips ECG 7581A amplifiers. The bias setting is 60mA, as specified by the manufacturer. These vacuum tubes are military tubes, complying with the US military's JAN standard, which stands for Joint Army Navy. We select only high-quality JAN tubes with high performance. We previously used GE 6L6GC tubes from the US, but replacing them completely transformed the sound, resulting in a crystal-clear sound. We also replaced all miniature tubes where we found a noticeable deterioration in sound quality through measurement and listening. The secret to using vintage amps with many vacuum tubes is to fully replace them with carefully selected, high-performance tubes to maximize their performance. If you're unsure whether a tube is new or used, or if they're expensive, it's a good idea to buy a lot of Electro-Harmonix vacuum tubes from Russia, measure them, and select them. Other tubes, even those from the highly acclaimed JJ company, are often just imitation 12AX7s or 12AT7s. Since they are not manufactured to the same specifications as vintage MT tubes like the official 12AX7, 12AU7, 12AT7, and 6DJ8, they often fail to function properly with ARC amps, resulting in no sound. This amplifier is often cited as prone to hum and frequent problems, but the main cause is contamination and interference from the power supply. As for maintenance, the majority of noise is caused by capacitor drying due to vacuum tube failure or aging. There are only four points to note when handling this amplifier: 〇 Use a noise filter tap on the air conditioner's power outlet. 〇 Replace the electrolytic capacitors, as they can cause hum if they are still attached from the factory. 〇 Install a ground lifter on the 3-prong inlet (only if hum is present). 〇 Replace the vacuum tubes if noise is present.
Uses a spherical horn (a spherical horn with an uncompromisingly ideal horn shape). avantgarde uses only a cable to connect the power amplifier to the voice coil. The characteristics of the horn and the driver design mechanically control the speaker's characteristics. As anyone who has built their own speakers or tried multi-channel systems knows, the network is the cancer of speakers. You'll notice how the raw sound of a network-less unit sounds fresher and purer. Even YG acoustic speakers have complex networks that make their sound heavy and muddy. avantgarde's network eliminates the midrange, and because tweeters, as you know, tend to skip, it only has a single low-cut capacitor. Furthermore, by biasing this capacitor to 100V, they created a circuit that eliminates zero-crossing distortion. The midrange driver is designed specifically for the 3kHz and 290Hz frequency bands, providing 6dB of attenuation above and below. An outstanding feature is the development of a dedicated unit that achieves 6dB of attenuation above and below. From the very beginning, the unit was designed with networkless operation in mind. By combining the characteristics of a 50-100cm spherical horn, we achieved a design that achieves a steep attenuation characteristic.No electrical circuitry is used. The design allows mid-range sound to be extracted solely through the characteristics of the unit and horn. By using a single amplifier rather than multiple amplifiers, we have overcome the issue of group delay characteristics, while achieving extremely high clarity and freshness without the muddiness of multi-amplifiers. The world's highest level of efficiency, 107-109dB, cannot be achieved with a horn unit alone. While the horn midrange and tweeter require an output of around 1-5W, the woofer only needs an amplifier of around 200W to match, as it only needs an output of around 85dB. By adopting the semi-active system, which is currently popular worldwide, and using a 500W or 1000W Class D power amplifier for the woofer, we were able to achieve an ultra-high efficiency of 107-109dB for the entire speaker. To connect to the avantgarde, simply connect the power cable to the speaker and connect it to the amplifier with a single cable. Direct-heated triode single-ended amplifiers are the world's best amplifiers, but they lack output, and compared to solid-state amplifiers, they suffer from weaknesses such as weak low frequencies and a blurred bass. The semi-active system overcomes these issues, allowing direct-heated triode single-ended amplifiers to sound flawless and effortlessly. "I absolutely cannot do anything but horn speakers." This is the true feeling, belief, and golden rule hidden deep in the hearts of veteran Japanese audiophiles. "Speakers are the overwhelming focus of audio." How can you be a Japanese audiophile if you've never used a horn speaker?! "Of course! A man needs a horn!"This is the consensus and heartfelt cry of veteran Japanese audiophiles.While JBL has spent billions on advertising and marketing, and its products have become technologically outdated, avantgarde has achieved sound quality that can compete with today's cutting-edge high-end speakers, even in a classic horn speaker. This is known only to those who have purchased avantgarde and a select few with keen aesthetic sense. Once you buy an avantgarde, you'll always own an avantgarde. With each generation, the connection between the horn and woofer has improved dramatically, reaching a level where you no longer feel any sense of incongruity. The avantgarde concept and design aims are enthusiast-like, and while there are probably others who could have come up with the idea, it's amazing that they were able to realize this enthusiastic concept. The fact that multiple manufacturers in Germany and China have imitated avantgarde is proof of this.avantgarde's first appearance in Japan was at a huge event in Hokkaido in the summer of 2003. I remember it being a huge event that overwhelmed the venue, but there's a report from an overseas event, complete with photos of older products.It was published in a back issue of Tube Kingdom. It began when a renowned Western critic heard avantgarde paired with a direct-heated triode and became enthralled with the sound. Since then, the combination of avantgarde and a performance-focused, modern-sounding, direct-heated triode amplifier has become widely known overseas, becoming the ultimate audio milestone. The article also includes a comment that reads, "It will be the savior of low-output, direct-heated triode single-ended amplifiers."Even today, the female president of A&M's exclusive distributor in Canada actively demonstrates AIR-TIGHT amplifiers in combination with avantgarde, achieving exceptional sales results.
Bright, thick and rich-sounding sound. Sound has a good warmth.
It has a sense of scale and massiveness, but is also very sharp and light.
The music is flowing and beautiful, and you are completely captivated by its awesome beauty.
It is as if the sound is coming out of the speakers.
A British sound that is very dignified and full of elegance. The emotion of the performer is directly conveyed.
The GEC KT-88 has the look of a king. It is without doubt the best KT-88/6550 output Kan.
The sound has an austere quality, with a rich sense of deadness, calmness and shade.
The GEC has the rich sound of a classic vacuum tube, and the sound is muddy, like a beam tube.
It does not have the clear, transparent sound of a direct-heating triode tube.
GECs are also black-plated, so there is no risk of fakes.
GEC KT-88s also have exceptional longevity and can be used for 10 to 15 years or more if played one hour a day, five times a week.
It is expensive, but the longevity makes it rather cost-effective if you grab a good bulb first.
Some audio technicians have fixed countless MC275s that came with GEC KT88s,
I have never seen a broken GEC KT-88 stuck in an amp that I have repaired,
The GEC KT-88 is so highly reliable that it has never been seen to be broken.
However, since there is an emission reduction, the sound quality deteriorates and the texture goes down,
However, the output tube failure is directly linked to the failure of the amplifier.
Amplifiers such as the Mcintosh MC275 and reissued MC275 UNISON RESEARCH Sinfonia and
audio research amplifiers from the 1970s and 1980s have a high probability of 80-90% if the tubes break during operation.
80-90% of the time, it will burn out one or two cathode resistors and fail,
The GEC KT-88, which never fails, is very useful.
This group includes Gold Monarch KT-88 > GEC KT-88 early, mid and late >
GOLD LION KT-88 > GOLD LION KT-88 reissued in the 80s,
Generally, the older the better the sound quality. The structure and other contents are all the same.
There is also a Russian-made reissue of the GOLD LION KT-88,
This is a modern tube with very good sound quality, but its construction and sound quality are not the same as the original GEC or GOLD LION KT-88.
It is not related to the original GEC or GOLD LION in any way, both in construction and sound quality.
General Electric 6550 United States
American sound, high temperature and dynamic, with a great sense of presence.
Hot and passionate sound. One of the best output tubes in terms of richness and density of sound.
The sound quality is strongly coloured and dense. The sound is too muddy to be used with high-resolution sound sources or modern recordings.
I found it unsuitable and not a match for electronic sound sources made with synthesisers as the sound is too muddy.
Because it is an old vintage tube, General Electric in the US has probably not aged it.
The GE 6550 has been used from NOS for less than 100-200 hours.
The initial failure rate for failure is just over 10%. The lifespan is not as long as the GECs,
Still, it has a longevity of three to five times that of modern tubes. Weaknesses include a slightly weak sound framework,
The weak point is that the sound framework is a little weak, especially in the low frequencies. When listening to modern rock music, the muddy sound and weak bass are quite fatal.
I found the weak bass to be quite fatal. The above impression of sound quality is based on
When I replaced the KT-88 with the Katsura KT-88, which was not opened in NOS state with the Buddha Jadis JA-80, I felt
I felt it strongly. My ears became familiar with the sound after listening to it with the Katsumitsu for a while,
I guess it was a reset. Therefore, the characteristics of the GE 6550 could be heard very well.
Also, the bias was applied so deeply that the ball smelled like it was burning.
The GE 6550's capabilities were demonstrated to the fullest.
I think that the ability of the GE 6550 was demonstrated without limit. In other words, the bias was
The GE 6550's ability is demonstrated to the fullest by applying a bias so deeply that it smells of burning.
The sound quality charm can be drawn out by applying the bias firmly and deeply. Incidentally, the Chinese-made
The Guiguang KT-88 is neutral and has no peculiar sound.
SOVTEK 6550 WE Russian Federation
Current Russian tube, clear and hi-fi sound quality. Physical characteristics (bass, etc.) are
particularly excellent. Although inorganic and tasteless in some areas,
The sound framework is also firm, with a neutral sound quality without any unnecessary colouration or peculiarities.
The sharpness of the contours also gives a good impression. High-resolution sound sources and subscriber music distribution
I felt that this bulb is most suitable for scenes where modern sound sources are enjoyed.
Russian tubes are mainly marketed for the guitar amp market, while Chinese tubes are mainly marketed for the home audio amp market.
The main marketing target for Chinese tubes is the home audio amplifier market, though,
I thought it was the ideal form of normal evolution for the modern audio market.
The current tubes, such as Russian and Eastern European JJs, all sound similar and to be honest
There is no big difference, and the difference in sound quality may be subtle,
This output tube was tested by a major tube amplifier manufacturer in the USA
The output tube has the longest life and least trouble among the current KT-88/6550 tubes,
We have been advised that this is the longest-lasting, least trouble-free and highest quality tube among the current KT-88/6550 tubes.
On a personal level, I cannot test that many manufacturers.
I would like to thank the American manufacturer for providing me with useful information.
In a comparison between the current KT-88 and 6550 tubes, the 6550 has a longer and longer life.
If you ask Japanese tube shops and amplifier manufacturers, they recommend it for sound quality.
Many recommended the JJ KT-88 as the current output tube.
For example, LUXMAN currently installs JJ KT-88 when the product is shipped.
In my house, the main unit is an AUDIO RESEARCH D-70 power amplifier,
The output tube is a SOVTEK 6550 WE, which is an important regulator that, if broken, will cause a major failure and, in the worst case, will lead to the destruction of the power transformer.
The regulator tube, which is very important and can lead to the destruction of the power transformer, is the highly reliable GEC KT-88.
Genalex Gold Lion KT88 Russian Federation
This tube also has a modern, clear, hi-fi sound quality.
What can be perceived from the reproduced sound is a difference from other common current tubes,
It has a pleasing sweet gloss and colouration. From a normal Russian tube.
The sound quality is one step more refined and high quality. This one is an old memory I tried when I used to use an MC275.
I am writing my impressions based on old memories of trying them out when I used to use MC275s.
This bulb is a premium tube with a higher price point than others,
The aforementioned US tube amp manufacturers use this tube as a standard output tube in their amps when they ship them.
We assume that they would not have added it to the durability tests as an output tube.
Russian tubes currently cost at least ¥34,000 and up for four matched quads.
Russian tubes are also affected by the war in Ukraine and rising labour costs,
Although they are getting into Japan, they are entering via various countries and
Prices have risen considerably. The price of vacuum tubes is either going up or staying the same,
The PSVANE KT-88, which can be bought directly from AliExpress
currently around just over ¥16,000 for four Quads, including shipping, and the price is
It is by far the cheapest. We asked some engineers at a Japanese amp manufacturer who like vacuum tubes for their opinions.
I asked him for his opinion, and he said that the PSVANE KT-88 is well made in terms of both sound quality and quality.
I heard that the PSVANE KT-88 is well made in terms of both sound quality and quality. China has now developed rapidly and is now on a par with the developed countries.
China has developed rapidly and is now on a par with developed countries, but products shipped from China to Japan are
developing country quota and international shipping costs are left unchanged at the cheapest setting.
And a word of caution, these tubes are bought NOS (new).
At first listen, they sound hard and puffy and never sound good.
This means that the sound is hard at the beginning of the first listening session. After listening to music with the amp for at least 25 hours, preferably 100 hours or more, the
The tubes will gradually ‘open up’. You can judge the sound quality of a bulb by the sound of the blossoming vacuum tubes.
There have always been a lot of people who don't know this, buy one, listen to the sound, get discouraged and immediately give it away.
There have always been many. Russian output tubes, for example, have a black printed area on the print.
If the clear black print is still there, the bulb is not very good.
If there is a clear black print on the bulb, it is likely that the bulb has not been used much.
If you buy a used current output tube with a short lifespan, this may be a good reference for you.
Svetlana(S) 6550C Russian Federation Designed with a focus on modern, clear, and highly detailed high-end sound. The crystal-clear clarity and cutting-edge approach to resolving every detail of the sound were particularly impressive. The synthesizer's delicate, glass-like touch was particularly impressive. The fine-grained, flowing sonority is extremely detailed, yet vibrant and vibrant. Its expressiveness is vibrant and vibrant.While it lacks the deep bass of the Daruma tube KT-88, it still has some damping power. The SOVTEC 6550WE's structure features a double-plate construction with an additional reinforcing plate. This increases the tube's mechanical strength and reduces deformation due to vibration and heat. This output tube is very similar to the Russian-made SOVTEC 6550WE, but aside from the reinforcing plate, the structure below the plate, including the cathode, grid, and electrodes, is significantly different.
Listening test equipment Preamplifier audio research SP-8mk2 REV.7
Power amplifier audio research D-70 Jadis JA-80 MC275
Enjoy a special moment in breathtakingly beautiful scenery.
Located at an altitude of 1,100 meters, Biwako Terrace offers spectacular views.
Take a ride on the ropeway and when you reach the summit,
you can see Lake Biwa in all its overwhelming scale and power,
stretching from north to south.
I visited Biwa Lake Valley in Shiga Prefecture.
Upon arriving at JR Shiga Station on the Lake West Line from Osaka, the bus departs immediately,
making for a smooth connection. The bus to Biwa Lake Valley only stops at
Biwa Lake Valley, so it's simple and easy to understand.
The one-way bus fare is 410 yen.
On weekdays, there is one bus per hour, and on weekends, there are two buses per hour.
There is also a parking lot at the base of Biwako Valley,
so you can visit by car, but the parking lot was full.
The round-trip cable car ticket and Biwako Terrace admission ticket cost 3,980 yen.
The high-speed ropeway, which reaches an altitude of 1,000 meters in just 5 minutes from the base of the mountain, was very comfortable.
The capacity is approximately 116 people, as indicated inside the cabin.
The ropeway operates from 9:00 AM to 4:00 PM for both ascending and descending trips,
so if you arrive too early or too late, it may not be operating.
It is advisable to plan your return trip with ample time to spare.
Biwako Valley Live Camera Link
Weather in Otsu City, Shiga Prefecture
Additionally, weather is extremely important at Biwako Terrace.
When visiting for tourism, it is best to go when there is high pressure, clear blue skies, and strong sunlight.
July and August are recommended for summer visits, as the mountains in Shiga are often cloudy.
On cloudy days, you literally can't see anything. Visibility is zero.
Wake up early in the morning, check the weather on the live camera, and if the forecast is sunny, it's your chance to visit.
Upon arriving at the summit and exiting the cable car, cheers erupt from those around you.
“Wow, it's so cool!”
“Wow, this is amazing!”
Everyone is beaming with joy.
“It's so beautiful!” “It's so cool!” Everyone around us is raving about it.
The temperature is 19°C, which is 10°C lower than down below.
The lift ticket costs 3,000 yen. Lift tickets are only available at the ticket office at the base,
so I regretted not purchasing one.
The safety measures are simple, with only a safety bar that lowers down,
so it is not recommended for those with a fear of heights.
Those who visit on a sunny summer day will likely be satisfied with their visit.
In my opinion, it rivals Kamikochi in Nagano Prefecture,
and is one of the top tourist destinations on Honshu Island.
The view was truly breathtaking and absolutely stunning.
