TDA1524A Tone Control IC

[WildSwan]

I built a project, a tone control for the 22W TDA1554 Power Amp. It is now working. But my problem is I can seem to make it sound loud unless I turn the vol to the max. And it starts to sound only whent the volume control is turned more than a quarter turn.

Now, there is no problem with the sound. An I read somewhere that this fault is inherent when using a linear pot and that I should use a logarithmic pot. I can't find such pot here in the Philippines. Is there a work around this problem?

Thanks.

 

[audioguru2]

Hi WildSwan,
Nearly all volume controls are logarithmic, also called "audio taper" to match the logarithmic sensistivity of our hearing to loudness.
If a linerar pot is used instead then the output will be near max for most of the rotation then a sharp drop when the pot is turned to nearly zero. At max rotation a linear pot and a logarithmic pot will both produce the same volume.

The TDA1554 has a voltage gain of only 20 if it is bridged. Then the input must be a pretty high 412mV RMS for it to produce full output of 17W into a 4 ohm speaker.

The TDA1524A Tone Control IC has a max gain of slightly more than 10 which should fix your problem. It uses linear pots and its electronic circuit makes the logarithmic contour.

Did you wire the ICs like in the datasheets?
What is your input that is so low?

 

[WildSwan]

Hi, Audioguru!

I wired the Tone control as per data sheet specification.

I am using a Piezo Type Stereo tuner as my test input.

 

[audioguru2]

I wired the Tone control as per data sheet specification.

I am using a Piezo Type Stereo tuner as my test input.

What is "a Piezo Type Stereo tuner"? Tuners don't use piezo. Quartz crystal maybe?

 

[Sukhbinder]

The TDA1524A IC is a bit fussy when it comes to performance, i once tried making the circuit given in the datasheet. it worked fine with my HA1392 based amplifier but didnot work with my STK465 based amp. the bass corection network works great and the contour setting settinh really works. there is another alternate to the TDA1524A from national semiconductors, its the LM1036 Dual DC Operated Tone/Volume/Balance Circuit. it works similar to the TDA1524A.