transformers


Toroidal Power
for all Studer A68, Revox A740 / B740, B750 and B250
Why do the transformers of Revox tend to hum?
Well, many amplifiers from other providers are not even as old as the transformers could hum!
The Studer A68, Revox A740, B740 and B750 are over 40 years old and the B250 amp is well over 30 years old.
The cut-tape transformers used by Revox are already excellently suited for the audio sector. Nevertheless, toroidal transformers are also the better choice in the audio sector. Toroidal transformers have a relatively high efficiency, which is particularly important here, small size and only a very small stray field.
Only with a toroidal transformer can the Revox B750 amplifier also drive loudspeakers of the hit "Quadral Titan" or "Infinity Cappa"!
Installation in Revox B750

370 VA


is the power of the new toroidal transformer.
This is more power than needed is available.
Revox B750 Ringkerntrafo EN 61558
Toroidal transformer 370VA Revox B750, revox-online
Revox B750 with original transformer

The old transformer


must first be expanded.
For this purpose, all cables coming from the transformer are disconnected at the voltage selector switch. Then all other connections to and from the transformer are removed and the transformer unscrewed and removed.
Revox B750 mit Original-Trafo

The new transformer


can be installed after removing the old transformer. To do this, first mark the borehole for the central fastening, drill a 5 mm hole and screw the transformer with one of the existing screws.
Revox B750, Bohrloch für den neuen Ringkerntrafo von revox-online kennzeichnen
Mark the Revox B750 drill hole for toroidal transformer
Transformer, manufactured according to EU standard EN 61558

The strands

are prefabricated by us and grouped together. The strands of the output stages (red) are equipped with 2.8 mm x 0.8 mm flat plugs. We manufacture the transformers according to the currently valid EU standard EN 61558.
The transformers are CE-conform!
Work extremely carefully and concentrated and have the work checked by a specialist.
We assume no liability of your work!
Ringkerntrafo, EU-Norm EN 61558, CE-Conform

embarrassed


Bundle all strands and lay them so that the strands can not rub or cause short circuits anywhere. You will receive enough shrink tubing and cable ties.
In the manual all necessary steps are described exactly.
Revox B750 mit neuem Ringkerntrafo von revox-online
Revox B750 with new transformer
Revox B750 power plug

Power jack

To guide the new stranded wire through the protective tube to the mains connection socket, the new and the old stranded wire are soldered together and then pulled through. Please observe all specifications of protection class II. The connections must not be released by themselves, even under strong heat. For this purpose, the strand is pulled through the eyelet, then twisted and then soldered!
Revox B750 Netzbuchse
Installation in Revox A740, B740
852 VA transformer for Revox B740, A740 and Studer A68 revox-online

852 VA


ialready a house number!

Here, the inrush current must be limited. Without this measure you would have to run to the distribution box more often to switch on the fuse several times,
Ringkerntrafo 852 VA für Revox A740, B740 und Studer A68 von revox-online

Original Impact


Once again, the old transformer of the Studer A68 or Revox A740, B740 amplifiers must be removed.

DANGER! Disconnect the mains plug before opening!
the old Revox A740, B740 ribbon transformer
Original Revox and revox-online transformers

comparison


Even the old transformer is a real knocker!
Both transformers are suitable as additional weights for the sport - but are too expensive and too bad!

well

mark for the central fastening of the transformer.
Since the Revox A740 or B740 and the Studer A68 have very little headroom, you should use the transformer to determine the exact position and mark the position of the drill hole.
Mark the drill hole in the Revox or Studer amplifier
Central earth point Revox a740, B740 revox-online

central mass

At 850 VA power, everything has to be right!

Therefore, we carry out the work exclusively in our company. Our specialist staff is trained and familiar with the subject matter.
Zentraler Massepunkt Revox B740, A740 mit Ringkerntrafo von revox-online

secondary voltage

To make it not too easy Revox has reached deep into the box of tricks and nested the tension weird.
Danger! Everything over 42 V is no longer low voltage!
Revox B740, A740 secondary voltage revox-online
Connection diagram Revox B740, A740 revox-online

connection plan

The documentation of the changes, the work to be carried out is also very important for us in the house!
Quickly one has confused red with red, brown with brown or blue with blue and so on.
Anschlussplan Revox B740, A740, revox-online

A dream

For the power amp Revox A740, B740 or Studer A68 we offer many spare and accessory parts. We offer 22,000 μF charging capacitors with 80 V withstand voltage, 2,200 μF / 100 V with central mounting, bulbs, capacitors, trimmers, transistors, repair kits, refining and much more!
Revox B740, A740, revox-online
Installation in Revox B150, B250 / E / S
Revox B250 toroidal transformer installed by revox-online

Trafo in B250

We were once asked how big the power of the Revox B250 amplifier is with the new transformer.
Look at the picture, you will not get more than 520 VA for the transformer! No matter how big the performance is, that's all!
But rest assured, there is more than enough power and plenty of reserve!
Revox B250 mit 852 VA Ringkerntrafo von revox-online

construction

Thanks to many small design features, we have been able to install the new transformer without any changes to the Revox B250 integrated amplifier (no additional hole or other work). Theoretically, it is possible to reinstall the old transformer - and you can not see anything!
RKT in Revox B250 mit neuer Netzteilplatine von revox-online
transformer in Revox B250 with power supply, revox-online
Revox B250 connections for power amplifiers, revox-online

Connectors

Of course you will get the right connector!

Everything is pluggable except for the 2 x 230 Vac strands. Had we still got the matching power sockets, the installation would have been possible without soldering. Remember the danger of mains voltage, please observe the regulations for protection class II.
Revox B250 Leistungsendstufen revox-online

New power supply board

Not least because of the new power supply PCB, it was even possible to offer an internal solution of the transformer with plenty of power. The PCB contains all the components of the old power supply board plus the five secondary fuses!
neue Netzteilplatine von revox-online
new optimized power supply board from revox-online
Revox B250 power supply board old and new from revox-online

Old and new

After many inquiries and plenty of thought, we came up with the idea to replace the original power supply board with a new circuit board. The Elkos then got bypasses and the tensions were adapted to the needs. No 24 V relay should be operated with 32 V. Take a look!
Revox B250 Original-Netzteil und von revox-online

Revox B250 S

Everything fits! The installation, the sound, less power loss, less heat!
If other competitors try to discredit the Elkos with some pseudo-leakage currents, we have the perfect internal solution for you. Ultimately, it's about the preservation and the value of the Revox devices!
Revox B250 S mit neuem Netzteil von revox-online
Revox B250 S with new power supply - the internal solution
Transformers in our shop

Here you will find toroidal transformers for Studer and Revox devices.
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