Exploring the Toshiba 2929 Audio IC - Seeking Guidance

Greetings fellow audio enthusiasts,

I hope this message finds you well. I must admit that starting this new thread feels a bit daunting, but I'm excited to share my new journey with you all. For those who have followed my previous thread, you might remember that I'm on the spectrum (autistic), and this community has been an incredible source of support and knowledge as I delve into the world of audio electronics.

My journey began with a simple question about the AX11 from Apex, but it quickly became apparent that my understanding of transistors, biasing, and even basic electronics was sorely lacking. It's as if I tried to play a 7-string guitar without knowing what a mode or scale was - and trust me, it didn't end well.

This time around, I reached out to an old friend who's been a guiding light on almost my entire life. He kindly reminded me not to put the cart before the horses and promised to send me something to kickstart my learning process. A few days later, a package arrived, and despite its size, it contained only a couple of ICs. I couldn't help but wonder what I was supposed to do with them.

Inside, I found a note from my friend: "Figure it out for yourself; it's not rocket science." He certainly has a knack for sharp humor. So, what did he send me? Well, you probably guessed it from the thread's title - a couple of Toshiba 2929 ICs.

I dove headfirst into researching this mysterious component, only to find a not-so-user-friendly datasheet and a distinct lack of audio amplifier schematics using it. It seems that some datasheet writers forget that not everyone is on the same level of understanding.

Now, while I understand this isn't rocket science, I still find myself in need of some guidance on this less popular audio IC. Supposedly, it's a 45W 4-channel grail (according to my friend), with THD as low as 0.007% and PNP/NPN DMOS output. Has anyone had any experience with this little unknown gem?

My goal is to build something with it and learn along the way. However, I'm stumped when it comes to deciphering the capacitor and resistor values. This leads me to question once again who might have authored such a confounding datasheet.

So, I turn to this wonderful community for assistance. Can anyone shed some light on the component values and guide me on how to connect two unbalanced inputs to produce four channels? I have a hunch that it's possible, but I'd greatly appreciate any insights you can share.

Thank you in advance for your support and expertise. Let's embark on this new adventure together.

Warm regards
 

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I'm not concerned about how it might sound or whether it's intended for vehicles; I simply want to construct it, experiment, and gain knowledge from the process. Regarding the four outputs, I plan to install a speaker in each corner of my studio.

Could you provide guidance on setting up the four outputs and determining the appropriate resistor and capacitor values?

I'm seeking guidance because the datasheet explicitly mentions, 'Components in the test circuit are only used to determine the device characteristics. It is not guaranteed that the system will work properly with these components.' And I am somewhat puzzled as to why the test circuit mentions only one resistor. Your expertise would be greatly appreciated in clarifying this.
 
Table 6 gives the capacitor values and the test circuit is okay to use.

Feed the left channel source to two inputs and the outputs of them to the front/rear speakers and your right channel to the other two inputs etc.
You'll need a high current 13v supply, eg CB radio power unit.
 
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Thanks


Do I need to include output capacitors?

What about the input capacitors? Should I use one capacitor for Input 1 and 4, one for 2 and 3 or is it advisable to stick with one capacitor for each input as it currently is?

If I opt for just two speakers, would that still work effectively?
 
Each input must have it's own capacitor as it is there to isolate any DC on the input and output of the source.

The speaker output is a bridge tied one, where the the speaker is driven with antiphase signals. from a pair of amps. This means that there is double the voltage swing and therefore 4x the power compared to a single amp running from such a low voltage as a car battery.
No capacitors are needed and each output would be around 1/2 supply volts with no signal.

If you want to use two speakers then leave the unused outputs unconnected and also the unused inputs. You cannot connect the outputs in parallel.
 
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It seems like I'm navigating through this with no clue at all. I'm essentially winging it, and honestly, my judgment might not be top-notch.

Regarding the electrolyte caps, I'm unsure if they're in the right direction. Additionally, I'm completely baffled about how to connect pins 4 and 22, and I'm not too confident about my approach with pins 13 and 25 either.

If I mess this up, I might as well take up skiing – it definitely sounds easier than this.
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C4 is not an electrolytic, its a 1uf film or similar which are not polarised. This is also true of C6.

C2 looks like it's the wrong way round - I'd have thought +v to the chip. - it's correct on page 2.

4 and 22 have to be connected to the supply - i.e. pins 6 or 20 - see the entry at the bottom of th table on page 8 of the pdf.

You must also attached the ic to a substantial heatsink otherwise it will overheat and shutdown.
 
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No point in using much high input caps because the input impedance is high (90k). You won't hear any improvement in low frequencies even by doubling the value. Normally electrolytic caps are never used as input capacitors and certainly not of such a high value.
Also, pcb manufacturers don't like having to etch away large areas of copper and some won't accept layouts with them.
The answer is to use your pcb program's ground plane function which wil fill in most areas and can be connected to the 0v pin only at the power connection.

The power & loudspeaker tracks must be much much wider as several amps can be flowing and maybe much thicker copper used for the pcb.
 
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No point in using much high input caps because the input impedance is high (90k). You won't hear any improvement in low frequencies even by doubling the value.
Today I tried searching for 'Input' and was fortunate to discover the valuable input resistance data of 90kΩ for the TB2929. I acknowledge that I should diligently read datasheets from top to bottom, but sometimes my focus and self-esteem can be challenging obstacles. That's why I've been asking numerous questions, and I want to express my sincere gratitude for the invaluable assistance you've been providing so far.


Normally electrolytic caps are never used as input capacitors and certainly not of such a high value.
When deciding between ceramic and film capacitors for the coupling capacitor, which type would you recommend? Ceramic is indeed much cheaper but I I've heard that polypropylene film capacitors are well-regarded for audio coupling applications due to their desirable characteristics. But in my searches I found that film (Polyester, not PP) capacitors strike a balance between cost and material type.

Also, pcb manufacturers don't like having to etch away large areas of copper and some won't accept layouts with them.
I'm not entirely clear on what you meant by that. Could you please provide more details?

The answer is to use your pcb program's ground plane function which wil fill in most areas and can be connected to the 0v pin only at the power connection.
Could you please, clarify if the preferred approach is to have one ground plane for the power supply and avoid connecting the ground from the Single-Ended inputs directly?

The power & loudspeaker tracks must be much much wider as several amps can be flowing and maybe much thicker copper used for the pcb.
I've tried using wider traces, but the IC being at the top did not help much. could it be placed on the center?
 
I wish to begin by expressing my heartfelt gratitude for the unwavering effort you've extended to assist me. Your dedication and commitment to helping others have not gone unnoticed, and I deeply appreciate your invaluable contributions.

Almost three years ago, I experienced a profound loss when I bid farewell to one of the few remaining friends I had. He was not only a dear friend but also an accomplished electronics engineer. He played a pivotal role in guiding me into the intricate world of electronics. Our lengthy conversations delved into the intricacies of audio amplifiers and their inner workings. Tragically, he succumbed to cancer, leaving behind a void that defies description.

It is this void, this yearning for knowledge, and my fervent desire to grasp the intricacies of electronics that led me to this forum. I sought connection with individuals who might generously share their wisdom and insight. You see, I face a unique challenge in learning complex subjects like electronics—I require the ability to visualize the concepts I am striving to understand.

Once again, I extend my heartfelt thanks for everything you've done.

Regarding the currents and track size, I am aware of the general guideline suggesting approximately 0.04 inches of track width per Ampere. However, the tight spacing between the pins of the IC leaves me with limited room for maneuver. The width of the track as it exits the IC is as wide as I can make it given these constraints. My question, therefore, is this:

Is it feasible to have a small section of the track, immediately as it exits the IC, at its maximum possible width, and then transition to the ideal track width for the remainder of its journey until it reaches the output and power supply inputs?

Your insights on this matter would be greatly appreciated.

Thank you for taking the time to read this message.

Warm regards
 
PCB Design may seem relatively straightforward to many of you, but for me, it carries immense importance. The successful completion of this project represents a significant milestone in my journey, one that I find challenging to express adequately.

If anyone could kindly spare a moment to review and verify the connections, it would be an act of generosity that I would deeply appreciate. Your insights and expertise are invaluable to me, and your assistance will contribute significantly to my understanding.

I eagerly await any responses or guidance you can provide. Thank you in advance for considering my request.





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Your grounding scheme is not correct. Pins 1,8,2,18,24 should be tied together with a fat trace to neg pin of C6. Current connection to Pin1 should be removed.
AGND net and GND net should be the same, connect them together, then to pin 13. If the naming of the nets is driven by your PCB software, that means your schematic is wrong / incomplete. Post last revision of the schematic which produce this pcb layout.
Stick to the DS especially for the two ground nets. One got a down arrow symbol (signal ground), the other an Earth symbol (power ground). They shouldn't be mixed but tied together at only one place of the pcb.

According to DS Cripple (C2 on DS, C7 on your layout) should be 10uF. A bit more won't harm, but 4700uF seems exaggerated.
In addition, your power tracks and speaker out tracks are too thin, those are high current tracks, make them wider.

Other issues may exist : I haven't made an extensive review.
 
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