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 Post subject: TDA2030A gain reduction for Headphone Amp
PostPosted: 10 Jul 2017, 05:59 
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Joined: 10 Jul 2017, 05:55
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I have a TDA2030A(here is the datesheet of tda2030a) based amplifier that should make a decent headphone amp except that its gain, at about 32 dB, is way too high.

It would be easy to change the gain setting resistor or even put in a switch to change the gain from say 10 to 15 to 20 dB for proper Headphone use. But there is a problem.

The TDA2030A data sheet says the chip needs to run at a gain in excess of 24 dB to maintain stability.

A resistor could be placed in series with the output. But that destroys damping factor and sound quality. That is not an acceptable solution.

Meier Audio uses the TDA2030A in their Corda Brick. It has switchable gain of -1 to +14 dB. So how do they do that with the TDA2030A?

Anybody got a working circuit they will share that gets the TDA2030A down to a stable switchable gain of 10-15-20 dB?

Suggestions?


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 Post subject: Re: TDA2030A gain reduction for Headphone Amp
PostPosted: 16 Jul 2017, 14:05 
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Joined: 20 Jun 2015, 14:39
Posts: 936
Just a few random thoughts...
* One solution might involve putting a pad on the input (before the input cap).
* What's the impedance of the headset you are going to use? If it's on the high side (e.g. 30 ohms), how well will the amp drive it? Will it maintain stability? Will driving a higher impedance load effectively reduce the headset volume to a listenable level?
* Instead of a resistor in series with the output, how about a resistor (e.g. 11 ohms) in parallel with the output. It would be terribly inefficient and both the amplifier and the resistor would have to dissipate some power, but maybe the damping factor would not suffer as much. Probably not practical.
* What would be the result if the amplifier's power supply voltage was reduced? Probably just a reduction in headroom, which is not a good thing.


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Tom


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 Post subject: Re: TDA2030A gain reduction for Headphone Amp
PostPosted: 16 Jul 2017, 19:51 
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Joined: 18 Dec 2015, 15:35
Posts: 160
For the data sheet https://goo.gl/gxekWc instead of wondering around the endless data sheet providers

Headphone Amp? That device is for driving speakers at 18 watts and push-pull at 35 watts. Here are some Headphone amps: https://www.headphone.com/collections/headphone-amps and they all have one thing in common, low wattage, millawatt to 1.5 watt but the frequency responce and low noise responce is in relation to what you pay, $59~$1899 with power rating like-> Output Power: 500mW@32ohms / 200mW@600ohms (RCA input), 2000mW@32ohms / 800mW@600ohms (XLR input)


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