Products > Test Equipment

To all the audio guys out there.

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timeandfrequency:
The audio analyser pope owns already outputs + 20 dBu (11 Vpeak) which can be generated by using ± 15 VDC rails.

As pope needs signals with higher values, a low distortion PA (<> Class C) needs voltage rails above the 15 VDC mark.

With ± 22 VDC (max value for most opamps), 17 Vpeak (24 dBu) can be obtained, best case. That is just 4 dB more that the analyser.

For more output voltage, amplifiers that accept higher voltage rails are required.
By pushing the LM1875 that trobbins suggested to its' limits (so 60 VDC or ± 30 VDC supply), 24 Vpeak (27 dBu) should be possible : a 7dB improvement.
But pushing a PA to its' limits always raises distortion.

Messtechniker:
I also built this one using an OPA 551 PA

djsb:
They have a transducer driver

https://quantasylum.com/collections/frontpage/products/qa461-transducer-driver

The forum is probably the place to ask about your requirements

https://forum.quantasylum.com/

I have a QA403 but have not had a chance to use it yet. It's a nice piece of kit.

David Hess:
That OPA551/OPA552 is a good option for the simplest design with good performance.  I wonder if a hybrid design using something like an OPA1611 could do better.  Noise would be 1/3rd, and distortion potentially up to -136dB instead of -106dB, which I think points out the problem of combining the best audio performance in a high voltage and current part.

It is difficult to evaluate the LM1875 because the datasheet only discusses performance with 4 and 8 ohm loads.  I have used parts like that within the feedback loop of a better amplifier for lower distortion and noise, but the frequency compensation can be difficult.  Better is to use a power current feedback amplifier, but I do not know of any with higher voltage ratings, leaving discrete designs like the one I posted.

The Soulman:
Easier to implement is a dedicated line-driver ic such as:
https://thatcorp.com/that-1606-1646-balanced-line-driver-ics/

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