new Power-on delay 2025Revox A77
for all Revox A77 MKI, II, III and IV
The new switch-on delay for all Revox A77 models ensures improved switch-on and switch-off behaviour. In particular, the switch-off time has been significantly reduced, making the switch-off pop less startling. The switch-off noise cannot be completely avoided. To do so, the circuit would have to be able to read your mind before you press the power button, switching off the signals and the VU meters. Even in the new circuit, the signals are not routed via the relay contacts! Installing the new power-on delay is just as easy as with the previous version. The installation remains unchanged!
new ESV 77 Version 1
We offer the new power-on delay in two versions. Version 1 is without VU meter protection. This version is completely pluggable. This is particularly simple and cost-effective!
ESV 77 Version 2
The second version also includes VU meter protection. This requires four additional wires to be soldered in addition to the existing wires. This is very easy to do!
Electronic
The technical complexity has increased significantly compared to the old circuit. Instead of two transistors, there are now five transistors installed. The circuit board is larger. The connections and their colours have remained the same. Here we are following the REvox A77.
Time
The delay time is approximately 5 to 7 seconds. In most cases, this should be sufficient to effectively suppress the switch-on pop! The new circuit also does not require electrolytic capacitors, making it very durable.
Installation of ESV 77 without
VU meter protection
Remove A77 from the case
Loosen the 4 rear housing screws and tighten the dummy plug for the wired remote control.Pull the device forward out of the casing and lever it forward. This is a bit difficult, so please be careful and patient!
Output A77
Place the device on its side on a Styrofoam base with the power plug at the bottom. Remove three flat receptacles (AG9 brown, AG8 violet, and AG7 green) from the Revox A77 switchboard and insulate them with the included heat shrink tubing.
Connect output
Now connect the flat plug sockets to the ESV 77, as shown in the photo, and plug the wires coming from the ESV 77 onto the freed flat plugs on the Revox A77 (AG9 br, AG8 vio and AG7 gn).
Tension
Disconnect the yellow wire (ground, DF2) and the purple wire ( 27V, DF1) from the drive controller.
To improve visibility, the design wasinterference capacitor C113 desoldered.
insulation
Although the other flat plugs do not necessarily need to be insulated, the flat plug sockets of the power supplies must be insulated!
Connect voltage
The strands are exposed and therefore require good and safe insulation!
We supply the appropriate shrink tubing.
With a heat source (a lighter also works if you are careful!), the tubes shrink 3:1
Connect ESV A77
Now plug the flat plug sockets ge and vio, coming from the ESV 77, onto DF1 (vio) and DF2 (ge) on the drive control of the Revox A77.
cable ties
The power supply cable is fixed with two cable ties for optical reasons.
Platinum
The circuit board is attached to the Revox A77 chassis with a cable tie. The power-on delay circuit board weighs nothing, and the attachment is perfectly adequate! It's sufficient to just loosely tighten the cable tie.
Installation thw new power-on delay with VU meter protection
ESV 77
The new power-on delay for the Revox A77 is installed in exactly the same way as the power-on delay without VU meter protection. However, two additional white and two additional blue wires are required here. The white wires are used for CHANNEL I and the blue wires are required for CHANNEL II.
Cable routing
The wires are placed over the audio plug-in boards and routed to the respective Rec-Amp circuit boards of the Revox A77.
Rec.-Amp. .705
After removing the shield plate, the rec. amp circuit boards can be easily removed and modified. The modification is limited to soldering two stranded wires. It's not rocket science. The strands are then secured with cable ties.
Detail
On the left is ground, on the right is the VU meter signal before the 10 µF capacitor C509.
Nothing more needs to be done.
Now insert the circuit boards into the Revox A77, mount the shield plate and push the device back into the housing!
ESV A77
in our shop
Here you will find the convenience gain for your Revox A77
