AUDIO DESIGN GUIDE
Single Ended Amplifier/572

Listener Impressions by Francesco Pintavalle

that is the 'irony' of sound ...

 May 2000
0. Intro

It is an old story. Everything begin with the 300B/SE/PSE amplifiers, and you know the results. The last creation of this world renowned audio designer is a pretty big piece of hardware, full of iron. Nothing bad about this, we have a lot of famous examples, last but not least the 'Sakuma' amplifiers line.

This time the implementation has been based on a extremely simple design with the best components available. No parallel tubes handling significant currents, only one cap on the signal path. The supply stage looks impressive: multi transformer / Multi choke. The total for the irony pieces counts as much as 11 ...

As you may easily figure out, this 40Kg baby is neither so cheap nor so easily integrable with a normal listening environment (it's sized like 56x42x15 cm).

The technicalities

Actually are best described in the project pages, nevetheless I would like to recall some of the important aspects of this amplifier.

The chosen topology is very straightforward. It works in pure A1 class, the power stage is coupled to the driver tube with a 1:1 transformer - good even where the output tube should go A2 - the bias is fixed for the power stage (there was, actually, an automatic bias setup attempt). The power supply is very very strong with a double PI filer fed by a couple of good 5R4W.

1.Tubes: 6SL7, 6SN7, Svetlana 572/3, 5R4W.

2.Magnetics: Lundhal for all the magnetic devices.

3.Passive: Caddock resistors, Jensen caps and Elna Cerafine.

The Listening test has been performed in the usual Andrea's listening room, small and pretty dumped. The system setup was like the previous test:

Reference Equipment

1.Transport source: CD player Philips CD723

2.DAC: DAC 2.0 (see the project pages)

3.Preamplifier: None, direct connection to the Power Amplifier

4.Speakers: 2 ways self made with a TQWT low frequency unit with 20W75 Esotec Dynaudio driver (200mm) and a HD14D34HR Audax dome tweeter (34mm). Crossover point @1550 Hz 20dB/dec (1st order)

Software

In order to maintain a uniform judgement with the previous amplifiers, the software employed for the listening session was the near the same:

1. J.S. Bach: die Kunst der Fuge, Experion XX, Astree

2. John Hector Fiocco, Suites for Cembalo, Diana Petech, Fonè

3. Jean Henry d'Anglebert, Suites for Cembalo, Brigitte Tramier, Pierre Verany (Cembalo Hemsch/1754, mesothonic tuning, A=415Hz).

4.L. van Beethoven, 5th/7th/8th Symphony, ..., ...

5.Pink Floyd, ..., ...

6....Bruce Springsteen, Tunnel of Love, ...

7.... many CD Fonè

1. The listening session

This amplifier, again, is a fully transformer coupled system and it is easily audible. It's incredibly clean, faster than a 300B implementation, with both the ends of the spectrum extremely extended and powerful.

This is, for sure, the most noticeable feature. Even if it is rated the same as the 300B/PSE its capability to feed current to the speakers seems to be much greater, in particular the lower end is incredibly stable.

Furthermore, the sensation of 'openness' in particular referred to the female voice and to the brasses, it is really a strong point for the device.

Regarding the middle range, the result is not as pleasant as the 300B implementation, in particular it appears to be slightly depressed with respect to the lower and higher ends. Furthermore, it does not sounds as delicate as the previous amplifier.

The soundstage is really impressive, completely stable everywhere in the frequency domain, it is able in representing the acoustic scene with an incredible spatial precision and unmatched stability, much better than the SETA amplifier (and its soundstage was really beautiful!).

In general I do not like to make differences for a device 'destination' for listening, it seems reasonible that a good electronics is good listening at any music, a poor electronics is always inaudible. In this case I had a different impression.

My listening is mostly chamber music, quartets, keyboard compositions with many interest in Ancient Music and
Pre-Romantic age. This is the reason why I normally focus my evaluation sessions of the Andrea's amplifiers on
'sonically simple' and possibly 'isolated' compositions.

In this case, listening at my absolute reference recording (J.S. Bach, Die Kunst der Fuge, Hexperion XX, Astree) was
something 'different'. The ensamble is made by eight instruments, four voilas and four [fagotti]. The rendering was
really good, the positional details close to the incredible, the image expanded throughout all the room, in depth too.
The only 'strange' issue was the evidence (I am talking about details) of a bit more 'air' than I would expect for such a
kind of instruments. The impression was confirmed with the cembalo recordings.

Very different, and really stunning, is the Jazz and Rock reproduction. Everything becomes live, materic. Percussive
bass is reality, the overall impression is to be projected 'inside' a live performance. The higher end, is beautiful, open
and clear, and any element seems to be inside like an 'internal order'. With respect to this issue, listening to the 300B
amplifier seems to generate more 'confusion'. This is why I say the 'irony' of sound ...

Great result Andrea Ciuffoli, ad majora.

Francesco PIntavalle.