2014/12/29 created
2021/05/06 updated

The contents of this page were reprinted from the previous homepage of mine, 'Tonochi's Audio Room'. Some parts were edited.

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I have been building Audio System Gaudi since 1974. Now it is almost completed. It is nearly what I planned in 1974 (block diagram). I replaced the midrange unit (Fostex 6N-FE88ES) with a horn-loaded midrange driver (Fostex D1405+H400) in November 2012. Only difference between the current system and my goal is the midrange amplifier. I currently use a product of Flying Mole (DAD-M100pro) as the midrange amp. I have to design and build a new midrange power amp to achieve my goal.
[Block diagram]

This upgrade surely improved the system overall quality of sound by one rank or even two ranks. I feel that beauty and extremely high fidelity has been added to the features of the Gaudi sound, of which most attractive features have been dynamism and vividness. Now Gaudi can reproduce sound of any kind of musical instrument very precisely. A musical performance reproduced by Gaudi is so realistic that it sometimes startles the listener (for further details, see 'Rev.A: Upgrade of the midrange unit' in the page of SS-309).

Needless to say, the loudspeaker is the most influential component in an audio system to the system's sound quality. Particularly, the midrange unit contributes more to the overall sound quality than other LS units. It is my personal opinion since my youth, "the midrange unit determines the sound quality, and the tweeter determines the tone." This upgrade proved the opinion of mine.

It has been my dream since I was a junior high school student to design and build a high-end audio system for myself. Now the dream is coming true. Once Gaudi starts to play music, it quickly turns the living room, which is a room for daily living in a normal situation, into a mini concert hall, and the listener feels as if he/she is listening to a real musical performance. A daily ordinary time is changed to the happiest one. I think the quality of Gaudi sound, which has such magical power, is already very close to that of a high-end audio system.

Every time I had (a) guest(s), I have him/her/them listened to Gaudi sound. In many case, I received his/her/their praise even before this upgrade, but I suspected the half of the praises were flattery.
However, this upgrade improved Gaudi sound so good that it is truly praised. I know that not by words of the guests but by their facial expression. When a musical performance starts, most of them look startled. Then, some are listening absent-mindedly with his/her mouth open. Some lean forward and concentrate on the music with their shining eyes. Some are swinging without knowing. At the end of the performance, some applaud clapping hands. Some are moved to tears. Some say, "I felt as if I was listening to a real live performance."
Anyway, it seems that vividness of Gaudi sound gives listeners not a little shock.

The plan of an ideal audio system the 17-year-old boy made up 39 years ago is now becoming reality. It can safely be said that the boy's idea is being proved right. Even now, I believe that a tri-amplified system using horn-loaded loudspeakers and large woofers is the best solution to achieve hi-end sound quality, if the system is homebuilt.

This upgrade revealed one big problem: a class-D amplifier does not fit a horn-loaded speaker. It generates audible noises.
The current midrange amplifier in Gaudi is Flying Mole DAD-M100Pro, which is a class-D amplifier. Fortunately, the level of the noises is not so high that I plan to use it as it is for the time being. Anyway, DAD-M100Pro should be replaced with a linear amplifier as soon as possible. I gave a top priority to the design and building the linear amplifier (for further details, see "Rev. A: Upgrading the midrange unit" on the page of SS-309).

Equipment

Category	Model	Features	Description
ADP	NOBODY PS-104	*Turntable: SONY TTS-8000 *Tone arm: GRACE G-1040 *Cartridge: Ortofon 2M Red	I've been using it w/o major modification since 1982. I changed the cartridge from GRACE F-14MR to ORTOFON 2M Red in 2012. I'll continue to use it as long as it works.
DAP	SONY SCD-555ES	SACD/CD player	First generation SACD player. Also excellent as CD player having useful features such as a digital filter selector. I bought it in 2001.
DAP	Lenovo ThinkPad X121e	11" laptop PC	Storage: 128GB SSD. The combination of this PC and DS-DAC-10 functions as digital audio player. It also functions as measurement instrument w/ PicoScope.
DAP	KORG DS-DAC-10 + Aurorasound BusPower-Pro	USB DAC	The combination of this device and ThinkPad functions as digital audio player. The highest resolution is PCM 192kHz/24bit and DSD 5.6MHz.
Tuner	SONY ST-S333ESJ	Highly functional FM/AM tuner	Although it has various features, I use only basic ones. The sound quality is not so good because the FM radio waves, supplied from a cable TV station, are not strong enough.
Tape deck	AIWA EXCELIA XK-007	One-way, three-head cassette tape deck with stabilizer	Not so famous but excellent for its very high fidelity sound and high reliability. There has been no trouble except one belt replacement since it was purchased in April, 1989. It is now used as a tape player because the preamp PA-210 doesn't have REC OUT.
Preamp	NOBODY PA-210 Simplicity	Tube preamplifier All stages are SRPP CR-type phono equalizer Non-NFB flat stage Separate power supply	A tube preamp made in 2001-2003. Featured by out-and-out simplicity and low noise.
Network	NOBODY CD-211A A-NET	Solid state Three-way channel divider (network)	The first NOBODY-branded model that uses OP amps. Made in 2004. Revised in 2012. Crossover frequencies: 800Hz(18dB/oct), 7200Hz(18dB/oct)
Tweeter amp	NOBODY MA-208	Tube power amplifier 6BQ5 UL PP	Designed for horn-loaded tweeters. Made in 1999. Split load phase splitter; rectifying tube. Output power: 13W+13W
Midrange amp	Flying Mole DAD-M100pro HT	Mono digital power amplifier	Power amp for midrange/full-range. Warm sound like tube amp. Output power: 100W (8ohm)
Woofer amp	NOBODY MA-201C	Tube power amplifier 6CA7 UL PP	The first NOBODY-branded equipment, made in 1974. Used for woofers. The current revision: C Output power: 30W+30W
Loudspeaker	NOBODY SS-309A	Three-way speaker system *Tweeter: Fostex T925 *Midrange: Fostex D1405+H400 *Woofer: Fostex FW305	12" woofer-based three-way loudspeaker, made in 2001. It doesn't include network and attenuator since it's designed for the multi-amplifier system. Vented box for woofer. The midrange unit was changed from full-range direct radiator to horn-loaded midrange in 2012 (Rev. A).
TV	Victor LT-37H905	37" LCD flat TV	Used as a display of ThinkPad. The interface is HDMI.
Pnono cable	PS-104 -> PA-210	GRACE genuine cable	Low capacitance cable using 6N copper. It looks like the original cable attached to the tone arm. Its sound quality is better than the original.
Line cable	SCD-555ES -> PA-210	Handmade cable *Wire: BELDEN 8412 *Plug: Teflon RCA plug	Handmade cable made of balanced type shield wire. Though the RCA plug is a generic one, the insulator material is teflon. The plug's metal cover is not attached. Shrink tube is applied instead.
Line cable	PA-210 -> CD-211A	Handmade cable *Wire: BELDEN 8412 *Plug: Teflon RCA plug	Handmade cable composed of balanced type shield wires. One end of the cable is soldered in CD-211A.
Line cable	CD-211A -> MA-208	Handmade cable *Wire: BELDEN 8412 *Plug: Teflon RCA plug	Handmade cable composed of balanced type shield wires. One end of the cable is soldered in CD-211A. The wires were Audio Technica AT6A48 when CD-211 was built (2004). They were replaced with BELDEN 8412 in 2008. BELDEN is unquestionably superior. The metallic cover of the plug was replaced with a thermal shrink tube.
Line cable	CD-211A -> DAD-M100pro	Handmade cable *Wire: BELDEN 8412 *Plug: Teflon RCA plug	Handmade cable composed of balanced type shield wires. One end of the cable is soldered in CD-211A.
Line cable	CD-211A -> MA-201C	Handmade cable *Wire: BELDEN 8412 *Plug: Teflon RCA plug	Handmade cable composed of balanced type shield wires. One end of the cable is soldered in CD-211A.
Speaker cable	MA-208 -> SS-309A tweeter	Handmade cable *Wire: 47 Laboratory STRATOS *Plug: none	Handmade cable made of 0.4mm copper single wires twisted at 30cm pitch. One end of the cable is soldered to the output terminal of MA-208. The other end is plated w/ silver loaded solder.
Speaker cable	DAD-M100pro -> SS-309A midrange	Handmade cable *Wire: 47 Laboratory STRATOS *Plug: banana plug for isntruments	Handmade cable made of 0.4mm copper single wires twisted at 30cm pitch. Banana plugs for measurement instruments are attached to one end. The other end has no connector.
Speaker cable	MA-201C -> SS-309A woofer	Handmade cable *Wire: 47 Laboratory STRATOS *Plug: none	Handmade cable made of 0.6mm copper single wires twisted at 30cm pitch. One end of the cable is soldered to the output terminal of MA-201C. The other end is directly soldered to the terminal of woofer.
Room		25m2 living room	Fairly soundproofed. Slightly live at mid and high frequencies and slightly dead at low frequencies. Almost no standing waves thanks to the slant ceiling. Equipped with outlets for audio equipment; both 100V and 200V. The sockets are for medical use.

 

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