In switchable audio stage, is that necessary to provide load when not in use, for both inverting and non inverting op amp (like in the simplified schematic attached)? Is that a bad things to leave it without R Load?
An opamp has a low amount of output current. The datasheets for most opamps show a minimum load of 2000 ohms and the problems caused by the high output current. The opamps are shown to work much better with a load not less than 10k ohms. A few opamps can drive a load as low as 600 ohms.
An opamp has a low amount of output current. The datasheets for most opamps show a minimum load of 2000 ohms and the problems caused by the high output current. The opamps are shown to work much better with a load not less than 10k ohms. A few opamps can drive a load as low as 600 ohms.
Hi audioguru,
Thank You for the information, so I will go without R Load and check again each opamp load, as long as I remember some of the stage have around 2K loads and even that works, should I rescale the load to around 10K?
Hi audioguru,
I still experimenting and use +/- 18V power supply with around 23dBU target level for the various stage, mostly audio filter, gain stage (+/- 6dB) and unity gain buffer.
The IC are the variety of LM49710, NE5534, OPA134, etc, so I think Your direction for general good rule/safe value for resistive load is very appreciated.
I worked with telephone conference systems for a few years. My customers and I noticed that the sounds were very muffled so I measured the frequency response of a local round trip. 3kHz was down -10dB. I complained to Bell and they said it was normal. So I fixed it.
Do not tell Bell that I used +10dB of EQ transmit boost at 3kHz for telephone conference units. It made speech sound crisp and clear. Every time I demo'd it then it was sold.
I worked with telephone conference systems for a few years. My customers and I noticed that the sounds were very muffled so I measured the frequency response of a local round trip. 3kHz was down -10dB. I complained to Bell and they said it was normal. So I fixed it.
Do not tell Bell that I used +10dB of EQ transmit boost at 3kHz for telephone conference units. It made speech sound crisp and clear. Every time I demo'd it then it was sold.