Under the VAIC brand name, in the early 2000 years, a beautiful series was exclusively made by Mastersound. Though official sales and brand rights were not by Mastersound. This is long ago now, but transformers, materials, and electronic design was a combination excellent choices. Let me tell you I am a critical person with that, but yes I found this was done really so well. The best was of course the 32B, 52B, 62B reference.
The amplifier has a "screw less" deck, so all screw holes in the metal deck, are covered by a second, Z-shape folded plate. This plate and the transformer caps are Rhodium plated. Today, Rhodium is more expensive as gold, because it is used in exhaust converters for cars. In the 1990's there was no mass application for Rhodium. It was not cheap, but plating was at acceptable cost. It was even used to plate high quality cooking pans. These factories liked it, because you can make "Chromium" colored pans this way. Chromium however is very poisonous, so can not used for cooking. Besides, Chromium needs underlaying layers before you can apply it, and that would make it peel off. It is just second choice. Not so with Rhodium. From such a pans factory, came the transformer caps of the VAIC amplifiers. Really this is not a joke!
What I like about Rhodium is it's magic color. Though a white metal, it tends to reflect with a shade of grey-blue. Not very much, but it does so. Also, it is a hard metal, so even when wiped off many times unprofessional, still the amplifiers should shine like new.
The circuit of the 32B, 52B, 62B is basic, and down to earth and no fancy nonsense is found inside. So about the pre amplifier is nothing to say, other than it works very good, and uses a 6SN7. The drive circuit however is a class for itself. It uses a DC heated AV8B tube, at those days specially made for this amplifier, though also available as product by itself. However selling AV8B never was very successful, because DIY builders preferred cheaper tubes in those days, and amplifier builders do not use tubes which they can not sell for 2x the buying price. Which at the price of AV8B was not possible. So the VAIC 32B, 52B, 62B, was the main product which used the AV8B. However it was a great tube, and reminds me somewhat of PX25.
Today, everybody knows about the SAKUMA effect. Well almost everybody.. :) Mr. Sakuma was not the inventor of it, but he made numerous almost art-like amplifiers by this principle. Read more about it here.
The 32B, 52B, 62B amplifier uses the Sakuma principle not really, because for that, a third 32B, 52B, 62B tube would have to be used as a driver tube. Also it would have to be inter stage coupled. In that way reproducing the output circuit as a driver circuit. (Sakuma principle, to reduce distortion by compensation). This was not done here, but still, some part of it as achieved, using the AV8B capacitor coupled.
The rectifier tube is not visible on the pictures, but it is in the middle of the four transformers.
Output Circuit design is a dream. The Supply voltage can be changed with an internal switch to three voltages. If you service a Ref 32B, 52B, 62B, however it may pay off to take the screw of this switch off, and resolder this PCB part. Solder connections tend to get loose. The lower position is for 300B, the middle is for 32B, and the high voltage is for 52B and EML1605. By default the amplifiers where shipped with 32B settings. When replacing with new EML 520B-V3 or EML 1605 tubes, you can set this switch to the highest voltage.
We have the LAST FEW NOS Pairs of AV8 here. They can not be replaced easily by other tubes. So if you have a working 32B, 52B, 62B, and want to wait until the 8B stops working, you can risk it. But do not say later when they are sold out: "Ooohh... I whish I would....have......". I heard that so often with NOS tubes.
Heater voltage of the tubes is hand adjusted, and MUST be adjusted ALWAYS when replacing tubes. When you buy a used VAIC 32B, 52B, 62B, do not count on the previous user have done this right. It is already difficult to to clear to current users, that yes this is important, and no if "it works" that doesn't mean it was done right.
More information is give in the links below here.
ORIGINAL REMOTE CONTROL FOR SALE.
WORKS ON ALL VAIC AMPLIFIERS WITH VOLUME CONTROL
You may not be aware, but almost all VAIC amplifiers have a fully functional remote control unit inside, with a servo motor on the potentiometer. The idea of VAIC was, to sell the Infra Red transmitter later to the users. This remote control is out of production now, new price was 175€.
Used item, the bag is not with it. Shows normal use, piano lacquer still nice.
Price: 100€ for export, 119€ incl tax for Europe.
Look here, this is the lens of the Infra red receiver. If your VAIC has this element, it has a fully functional remote control inside, with the servo motor and everything. All you need is the remote control box as pictured above, and you can remotely turn the volume knob. So the knob turns up or down by motor control. And YES, this is inside almost any VAIC of later production. So look for the receiver lens as in the above picture. They are really nice quality items.