LM1875 bridge config

[Fast Eddie D]

There's a simple bridge LM1875 schematic on this site -

You don't need the bridging adaptor as one of the chips is setup using the inverting input.

Hacer amplificador de audio con LM1875, fuente simple o simétrica, simple o bridge

That's a very common circuit, but an inferior one. All the distortion from one chip gets fed to the other chip.

Here's a better circuit from the other page.

Here's a precision differential driver chip. DRV134PAG4 Texas Instruments | Integrated Circuits (ICs) | DigiKey It can drive two non inverting chip amps directly for use as a bridge amplifier. No funny values of resistors are required, but precision (1%) resistors are.

 

[Dimi Pana]

Thank you!

Link dont work because Rod's site moved.

Bridging Adapter For Power Amps

Also moved: http://www.ti.com/lit/an/snaa021b/snaa021b.pdf

Thank you, I did visit the active link and realized this is not really a bridged amp, but rather an "adapter" (?) to gang two amps together. Am I correct? What I am looking to do is a stand alone (stereo of course) power amp that will receive an already pre-amplified (line level) signal and "boost" it to ... well ... if I can get a clear 30W out that would be a resounding success. Ideally, I would love to find a schematic that incorporates at least Volume and Balance, plus if possible Tone controls (Bass, Treble for sure, Mid would be nice).

Thanks!

 

[Dimi Pana]

Thank you!

There's a simple bridge LM1875 schematic on this site -

You don't need the bridging adaptor as one of the chips is setup using the inverting input.

Hacer amplificador de audio con LM1875, fuente simple o simétrica, simple o bridge

Thank you, this schematic looks close (well, close enough for me and my limited level of expertise) to the one included in the TDA2030A's data sheet (from what I understand the TDA2030A and the LM1875 are pin-for-pin interchangeable and actually the latter is a much better choice). I have identified a few differences , I am not sure that is because these two IC chips despite their interchangeability, still, require a somewhat different schematic/wiring.

Anyway, I am tempted to try this and I was wondering if it is easy to (somehow, somewhere) insert a "balance" control and possibly a basic tone control (bass, treble, mid if only not too complicated).

Thank you!

 

[Dimi Pana]

Thank you!

That's a very common circuit, but an inferior one. All the distortion from one chip gets fed to the other chip.

Here's a better circuit from the other page.

Here's a precision differential driver chip. DRV134PAG4 Texas Instruments | Integrated Circuits (ICs) | DigiKey It can drive two non inverting chip amps directly for use as a bridge amplifier. No funny values of resistors are required, but precision (1%) resistors are.

Thanks for the feedback, I suppose the schematic, though uploaded 3 times, is the same correct? Now this design calls for a different IC, right? Or I could attempt it with any IC like the TDA20x0 or LM1875, or any drop-in equivalent? What I mean is, I checked the DRV134PAG4 and it is certainly a more advanced and I supposed modern(?) chip, but before I start spending on more expensive parts I just want to "cut my teeth" by ..."burning" a few older and obsolete ICs I have lying around.

Btw, can you provide a quick explanation of why/how the distortion in the previously proposed schematic feeds from one IC to the other and what is the expected THD at max 30W into an 8Ω load?

Thank you!

 

[Kshishtoff]

Hi Tincho!
TDA2030, TDA2050 and LM1875 are absolutely interchangeable. You can use TDA2030 bridge config for LM1875 without any changes in the scheme.
And if you use 4 Ohm speaker for your sub, you can try LM1875 with additional transistors. Cast a look at similar scheme in TDA2030 datasheet. Sound quality of that scheme must be enought for sub.
Or you can also install two LM1875 in parallel. One guy has done that scheme in real and he says it works fine for 4 Ohm load.