🎵 Connecting a Super Tweeter to Vintage Amplifiers (Audio Research, McIntosh MC240, etc.)
1. GEM TS-208 Super Tweeter Overview
Type: Ribbon tweeter
Frequency Response: 2 kHz – 100 kHz
Sensitivity: 101 dB/m (upper 7 kHz)
Impedance: 4 $\Omega$
Dimensions / Weight: W130 $\times$ H150 $\times$ D193 mm, 9.2 kg per unit
Durability: While clearly inferior to plasma ion tweeters, it offers near-permanent durability as long as the delicate diaphragm is handled with care and never touched.
Top Super Tweeters Available in the Japanese Market:
acappella TW-1S
REALON
GEM TS-208
Note on REALON (Plasma Tweeter): While extremely long-lasting (unlike the fragile acappella, which breaks easily despite its incredible sound), REALON has low efficiency and can only be used with speakers up to 88 dB. Even though it was heavily promoted by Audio Ippinkan, it somehow failed to gain popularity, with only about 9 sets sold through shops. Because the author uses high-efficiency speakers—such as the ALTEC 604C (103 dB), MILESTONE 604 (100 dB), and Avantgarde (107 dB)—REALON's low efficiency makes it incompatible.
2. Connecting to Vintage Amplifiers Using Barrier Strips & Pin-Type Banana Plugs
The Challenge: Vintage power amplifiers like the Audio Research D-70 use barrier strips (screw-type terminal blocks) for speaker outputs. Screws are arranged for each impedance tap (4 $\Omega$, 8 $\Omega$, 16 $\Omega$), originally designed to clamp bare wire or spade (Y-lug) terminals directly.
The Solution: To connect modern speaker cables equipped with banana plugs or to expand connectivity for banana plugs on these old screw terminals, pin-type banana plugs (needle plugs / flex pins) are used. One end is a 4 mm banana jack, and the other is a thin pin (usually around 2 mm) that is secured directly under the barrier strip screw.
Author's Setup: Previously, the signal for the super tweeter was split using Y-lugs and banana plugs since the speaker terminals accepted regular banana plugs. However, after switching back to vintage ALTEC 604C speakers (which use barrier strips), the author found this pin-type banana plug solution on Amazon.
3. Required Tools & Safety Precautions
Tools Needed:
Red and white heat shrink tubing: Essential for preventing short circuits. Since super tweeters lack protection circuits, any accidental terminal contact will cause damage and loss of sound.
Heat gun
Scissors
Pliers: To keep the plug safely away from the heat gun's direct heat source.
Pin-type banana plugs
Earthquake & Drop Protection:Audio spider sheets are extremely helpful for preventing falls. Having experienced the Great Hanshin Earthquake, the author prioritizes earthquake-proofing above all.
Tip: Tighten all connections firmly so they will never come loose.
4. Sound Performance & Effects
Even with high-efficiency speakers like the ALTEC 604C (103 dB), the super tweeter makes a noticeable and effective difference.
For speakers around 95 dB (such as the JBL S9500, M9500, and S5500), the upper frequencies show a massive and dramatic improvement, allowing the delicate, crystal-clear sound of the ribbon tweeter to be clearly heard.
audio research SP-8mk2 rev.7 2台 SP-8 1台 D-70 D-70mk2 D-115mk2の
六台のaudio researchのアンプを持っています。
この大好きなアンプの音をもっと良くしたい！
オリジナルの音を損なわず！と思いながら日々研究しています。
Replacing the Power Plug of an Audio Research D-70 with an Oyaide P-004 Power Plug
I purchased two Oyaide P-004 power plugs and replaced the molded power plugs on the directly connected power cables of my older amplifiers.
I would like to explain the specific procedure I followed.
The amplifiers I worked on this time were:
Audio Research D-70 (120V USA version)
Audio Research D-70 Mk2 (120V USA version)
First, cut the power cable very close to the original power plug using a cutter.
Remove the cable jacket and filler material with scissors.
Using a cutter, lightly score the black outer insulation of the power cable little by little. Occasionally bend the cable to deepen the cut gradually.
This is done carefully to avoid cutting too deeply and accidentally damaging the three internal wires.
Be extremely careful not to cut into the black, green, or white copper conductors.
Proceed slowly and carefully.
I strongly recommend purchasing a wire stripper.
A size suitable for a 2.0 mm diameter wire works well.
Simply clamp the wire and pull, and the outer insulation can be removed cleanly.
I performed this procedure on two amplifiers from the same era.
Both cables had clean, shiny copper conductors after cutting. However, one of the two units had a slight amount of oxidation on the surface of the copper wire, causing it to appear darkened.
The wire shown in this photograph was clean and shiny.
After carefully washing my hands with hand soap, I twisted the wires together.
Next, I performed soldering.
Place the soldering iron and solder directly against the twisted copper strands and cover the exposed copper with solder while applying pressure.
If the copper wire remains exposed, it will come into contact with air, oxidize, turn black, and deteriorate over time.
Use a 12 mm inner diameter black heat-shrink tube (20 mm width when laid flat) and a heat gun to finish the cable end neatly.
※ The heat-shrink tube step can be omitted if desired.
For the next step, make sure to pass the plug housing onto the cable before connecting the wires.
This is an important step because once the plug is assembled, the housing cannot be installed afterward.
For tightening the screws, I recommend using a screwdriver like the one shown in the photograph.
It is easy to apply force and very convenient to use.
Connect the wires in the following positions:
White → left
Green → top
Black → right
The effect of the platinum + palladium plating has made the ever-changing and richly colored sound of the Audio Research D-70 even more vibrant and expressive.
The sound quality has become more high-fidelity, and the result is excellent.
At first listen, the low frequencies seem to have slightly less weight, but in reality, the increased damping capability has made the bass lines much tighter and more controlled.
Among audio accessories, the power plug is one of the components that can have the most noticeable effect.
The part where the power is directly supplied is extremely important.
The most important factor is the material of the blades.
I believe beryllium copper blades provide the highest performance.
The P-004 is the most popular power plug among Oyaide’s lineup.
If you prefer a more natural sound, there is also an unplated version, so that option is worth considering as well.
Comparison of Impressions with Other Oyaide-Type Plugs
P-004
Transparency, speed, and resolution
Sound Characteristics of the Oyaide P-004 Power Plug
In one phrase:
“A plug that increases resolution, sharpens the contours of sound, tightens the bass, and enhances transparency in the mid and high frequencies.”
This type of evaluation is not limited to my own opinion; many other users describe it in a similar way.
1. Faster Sound Response
A commonly reported change among many users is:
Attacks become clearer
The edges of sounds become more visible
The initial impact of piano notes and guitar strings feels more realistic
This tendency is especially appreciated with:
Rock music
Jazz
Classical music featuring many percussion instruments
Vocal-focused recordings
because the outlines of instruments and voices become easier to perceive.
2. Increased Transparency in the High Frequencies
Rather than simply making the sound “brighter,” many people describe the effect as:
Removing a veil from the sound
Increasing the depth of the soundstage
Revealing subtle reverberations and fine details
With cymbals and string instruments, it is often described as:
“Not a harsh, metallic treble, but an increase in the amount of fine information.”
3. Tighter Low Frequencies
Regarding bass, many evaluations describe the change as:
× More quantity
○ Better control and damping
Specifically:
Bass lines become easier to follow
The outline of kick drums becomes clearer
Excessive bass swelling is reduced
Points to Consider / Possible Complaints
1. Some Systems May Feel “Too Hard” or “Too Sharp”
The P-004 is a type of plug that emphasizes information retrieval.
Therefore, when combined with:
Speakers that already emphasize high frequencies
Amplifiers with a metallic tonal character
Cables designed primarily for high resolution
some listeners may feel:
“The sound has become slightly colder”
“The sound has become more rigid”
2. Preferences May Differ Depending on Music Style
Tendencies considered suitable:
◎ Cool-toned sound
◎ High-resolution systems
◎ Monitor-like presentation
◎ Jazz, classical music, chamber music
Tendencies where preferences may vary:
△ Warm vocal-focused sound
△ Systems seeking an analog-like thickness and richness
Regarding the sound quality of the Audio Research D-70, it produces a magnificent, heavenly sound with a brilliant and radiant character.
True to its American origins, it also has a strong entertainment quality, with outstanding realism and a powerful sense of presence. Live music recordings are truly spectacular on this amplifier.
However, it is a sensitive and demanding machine, and it can be difficult to handle until you become familiar with it.
(Except for models such as the unreliable SP-10 and D-250, which are known to suffer frequent failures, most units can operate reliably once they are properly serviced and the owner becomes familiar with their characteristics.)
First of all, if the original electrolytic capacitors are still installed, I would like them to be replaced completely, except for the large blue block capacitors.
(The large block capacitors tend to lose capacitance less easily.)
The vacuum tubes should also be replaced completely at least once.
When people hear the phrase “gorgeous sound,” they may imagine a rough or coarse tonal character.
However, the high frequencies of the D-70 are beautifully polished, producing a sweetness and elegance that is difficult to describe.
Nevertheless, there is still a slight amount of coloration or roughness, and the overall texture feels somewhat less refined, revealing its age.
(The D-70 was manufactured from 1982 to 1985.)
For those who love this particular sound, it provides a heavenly listening experience every day.
However, when compared with modern high-end beam power tube push-pull amplifiers, its overall quality may receive a stricter evaluation.
Even so…
I absolutely love it!!!
I currently own six Audio Research amplifiers:
SP-8 Mk2 Rev.7 × 2 units
SP-8
D-70
D-70 Mk2
D-115 Mk2
My goal is:
“I want to make the sound of these beloved amplifiers even better!”
while also:
“Without damaging their original character and sound.”
I continue researching and experimenting every day with that philosophy in mind.
I visited Shizugatake, the site of an ancient battlefield in Shiga Prefecture.
The ruins of Kuwayama Naraharu’s fortress. From the mountaintop, you can see the entire battlefield.
There are also statues of military commanders and monuments commemorating the battle at the summit.
It feels like a prelude to the Battle of Sekigahara.
This is the spectacular view of the northernmost tip of Lake Biwa from the 421-meter summit.
It was here that Hideyoshi Hashiba and Katsuie Shibata fought a decisive battle to determine who would succeed Oda Nobunaga.
Following the death of Oda Nobunaga in the Honno-ji Incident,
Hideyoshi and Katsuie were at odds over who would succeed him. In March of Tenshō 11 (1583), both armies built numerous forts in the mountains
and faced off against each other. In April, taking advantage of a gap in Hideyoshi’s forces—which had marched to Gifu to defeat Oda Nobutaka and others—
Shibata Katsuie’s vassal, Sakuma Morimasa, launched a successful surprise attack on Mt. Oiwa, which was defended by Nakagawa Kiyohide.
The Shibata forces gained the upper hand. However, Hideyoshi returned from Ogaki—a distance of 52 km—in just five hours
(the “Great Return to Mino”), and thanks to the heroic efforts of the warriors known as the “Seven Spears,” Hideyoshi’s army emerged victorious.
This battle marked a major turning point for Hideyoshi on his path to unifying the country.
The seven young warriors who distinguished themselves under Hideyoshi at the Battle of Shizugatake
He was Hideyoshi’s younger brother. After Hideyoshi became lord of Nagahama Castle, Hidenaga served as his aide, supporting his brother as they fought in various regions.
He also participated in the Battle of Shizugatake and defended the main camp while Hideyoshi was away.
It would be a real shame to visit on a cloudy day, so
check the weather forecast the day before,
and make a final check using the live camera on the morning of your visit; if it’s sunny, it’s the perfect time to visit.
Weather Forecast Reference Sites
Lake Biwa Terrace Live Camera
Since it was a weekday, I rented a bicycle from the souvenir shop on the first floor of JR Kinomoto Station.
I visited on August 20, 2026, and since it was scorching hot that day, the trip was quite exhausting.
Since I had plenty of time, the clerk first gave me a pamphlet and, using a highlighter,
marked the route on a hand-drawn map right there, giving me detailed directions.
On weekends during the tourist season, a free shuttle bus runs from Kinomoto Station.
On weekdays, you’ll need to take a taxi or rent a bicycle. Walking is about 3 km—with some hills—and would likely take 45 to 60 minutes.
I rented a regular bicycle this time, but I strongly recommend renting an electric-assist bike if you’re not confident in your stamina.
Although there are a few buses on weekdays, it’s difficult to time your return trip to match their schedule, so
it’s best to either rent an electric-assist bike or take the free shuttle bus on weekends and holidays during the tourist season.
To use it, simply press the power button, set the assist level to low, medium, or high, and adjust the three-speed gears.
Usually, you’ll use the middle setting (around level 2). The assist level can be set to high.
If you plan to explore various areas, set the assist level to medium or low to conserve battery life.
Shizugatake has an elevation of 421 meters. A round-trip lift ticket costs 1,000 yen.
The lift doesn’t have any safety bars or anything like that, so I held on tightly to the main shaft and
the pipe near my waist.
On the way up, the lift’s estimated height above the ground is 3–4 meters, but
on the way down, the maximum height seems to be around 5 meters above the ground.
Occasionally, a jolt of vibration comes through at the joints, but
as long as you hold on tight, there’s absolutely no risk of falling off.
After getting off the Shizugatake Lift, you have to climb another 300 meters.
This part was quite a strenuous climb.
The plaza at the summit is quite spacious, featuring a bronze statue, a telescope, and historical sites.
Although it’s not quite as high as Lake Biwa Terrace, at an elevation of 421 meters, it does feel hot in direct sunlight, but
in the shade of the trees, it’s cool enough that you don’t need air conditioning—even in the middle of summer.
Captivated by the natural beauty of the Inner Lake Biwa region, I’ve now visited Lake Biwa more than 10 times.
I took the train two stops from Kinomoto Station to take a stroll around Omi-Shiozu Station for the first time in about five years.
I rented an electric-assist bicycle for 1,000 yen at the ticket window at Omi-Shiozu Station, headed straight ahead on the left,
and set out for the northern tip of Lake Biwa. (I highly recommend an electric-assist bike.)
If possible, I’d like to go by late August.
Staying hydrated is important. Please be very careful to avoid heatstroke.
Items to bring, if possible: a safari hat, SPF 50+ sunscreen, a 2-liter plastic bottle of sports drink,
a handheld fan, and energy drinks (such as Lipovitan D).
If you freeze the sports drink the day before and move it to the refrigerator before going to bed at night, it’ll be just the right temperature.
