The black front of the SA-T7 Diamond is identical to the MK version except for the lettering. What is new, however, is the higher-quality metal finish of the rest of the housing.

Actually, the work was done. With the MK version, Vincent had successfully updated the flagship SA-T7 preamplifier of the »TubeLine«. When I tested the device for i-fidelity.net in the summer of 2023, its sonic performance was convincing in every respect. So all good, right? But that's not how they think at the Baden audio brand, as Vincent manager Christian Fröhling explains: »Our developer had gained access to a brand-new batch of legendary Telefunken tubes and was convinced that the already very high quality of our SA-T7MK could be improved even further in a customised circuit with these tubes. So a prototype was built. After listening to it, the decision was already made. We didn't want to withhold such a level from the public.«

From the valuable stock of 1,600 PCF 803 tubes in mint condition (NOS = New Old Stock), Vincent intends to produce 250 units, each using four of these legendary glass bulbs. The remainder will be kept for servicing purposes. According to Christian Fröhling, this is the plan for the special edition of the SA-T7MK, named »Diamond« in reference to the Telefunken logo. Anyone who thinks they can read a problem with durability between the lines is on the wrong track. The service life of the tubes is estimated to be at least 10,000 operating hours. In reality, you can expect more, as the PCF 803 chip grid pentodes were originally designed for use in televisions and are therefore considered to be exceptionally robust. Nevertheless, Vincent is customer-orientated and prefers to keep a few extra units in reserve.

Like the SA-T7MK, an SA-T7 Diamond is based on the globally unique »BestPentode« principle. This patented circuit was developed by graduate engineer Frank Blöhbaum. The proven tube amplifier specialist has been contributing his in-depth knowledge to Vincent devices and the T.A.C. offshoot from the same parent company Sintron for many years. With »BestPentode«, developer Blöhbaum wants to question previous dogmas about the behaviour of pentodes and triodes in amplifier construction. He explains how they work as follows: »This circuit eliminates the current distribution noise caused by the additional screen grid current compared to the triode. At the same time, the generally higher amplification of the pentode is retained. In short: the pentode with the »BestPentode« circuit is just as low-noise as the triode, but with significantly higher gain and better linearity.«

The rear of the SA-T7 Diamond is proof of its diverse connectivity: six analogue inputs, three playback paths, two digital ports and the antenna for Bluetooth use. Thankfully, Vincent always indicates the phase on the mains socket. This makes it easier to connect the power cable correctly. To the left of this, we see the 12-volt sockets for shared commissioning with compatible devices as well as the »AUTO« function, which switches the device off after 15 minutes if not in use.

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