Dear visitor,
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OP-amp metronom

Operational amplifier for the R2R analogue converters TDA1540 and TDA1541A. CD players usually contain double operational amplifiers with two amplification stages in one housing, following the analog converter. One half is responsible for the voltage conversion of the audio signal, the other half is used for stabilisation with an upstream low-pass filter. However, these very different tasks are performed by identical halves. The OP-amp metronom combines two different individual OPs on one board as a direct replacement.

•  Optimized single op amps for different requirements of each stage
•  Best heat balance compared to double-OPs and conventional adapters
•  improved signal routing with anti-oscillation layout
•  minimal mass change due to new micro pin connectors
•  Plug'n Play replacement for all dual OPs behind R2R analogue converters

OP-amp metronom

•  OP-amp double 825-604
•  OP-amp double 604-825
•  OP-amp double 4031-604
•  OP-amp double 604-4031
•  OP-amp double 604-604
•  OP-amp double 825-825
•  OP-amp double 4031-4031

Selection criteria
Following the converter I recommend an AD825, then as filter and buffer an OPA604 - i.e. a double OP-amp with different equipment each half. This equipment is suitable for all CD players with double op-amp without any changes in the circuitry as a plug'n'play replacement. If you are able to change the circuitry in the CD player, choose a version with THS4031 instead of AD825. In this case an additional resistor must be added in series to a capacitor, which is located between the converter and the op-amp.

THS4031 I/U stage TDA1541

Example: Marantz CD94MKii

Different connections in CD players can e.g. Use either the first or the second half of a double op-amp first. Most devices require two double op-amps.

2x 825-604
The most common variant with the same wiring per stereo channel. For e.g. all Philips from CD100 to CD304 and also subsequent models such as CD460, CD650, CD880 ...
Grundig CD903, CD8400MKii, CD9000 ... CD9009 has 825-604 but followed by another 3x 604-604 as filters and output drivers, so a total of 8 double OP-amp.

2x 604-825
Some Marantz models use the second half of the op-amp first, such as. the models CD40 and CD50 ...

825-604 und 604-825
Models with different wiring for each stereo channel are e.g. Revox B225, Marantz CD84 and Sony CDP 337ESD ...

Marantz CD94 MKII first uses 2x 825-825. A subsequent filter section also requires 2x 604-604 and 2x single 604.

single OP-amp
A Philips CD960, Marantz CD94 and some similar models use 4x single op-amps. So two 825 and 604 are required here.

Questions about other models please via email.
OP-amp metronom single

•  OP-amp single 604
•  OP-amp single 825
•  OP-amp single 4031

Sought-after operational amplifiers are offered individually at the auction house at prices below those of the manufacturer. Checked offers were wrongly printed and could be identified as cheap NE5532/NE5534. Our operational amplifiers are exclusively purchased from the manufacturer's distributor. They are originals and therefore higher in price than counterfeits without adapter boards and low-mass solder pins.

metronom-module V2.0
no oversampling bridge