Making a list of HiFi quality chips.

Hello all..

For all of us.. We are here because either we are unsatisfied by Amps and audio systems in market, or because we are perfectionist , or just pure enthusiast , or even because we need satisfaction in our own projects.

In either way audio quality is our top concern. But there are few problems, like some of us don't have enough skills in making complicated circuits ( just because we just stepped into diy ) , or lack of availability of pcb/spares/tools etc, messing up with signals which may cause feedbacks and interferences, or even dont know the perfect ways to get perfect outputs.

So with all these problems, the solution is simple.. Building the simplest yet purest circuits. Which does not need more that 10 components , and thd values less than 1% at maximum output power. Of course those kinds of chips does exist, and we call it gainclones. Which are originally high power opamps . But still exist few problems with opamps.. They all need calculations for gain,cmrr, dc offset values etc... Also since its an opamp it does require skills to build an almost perfect circuit. I have seen people struggling in fixing feedbacks,noises, oscillations, blown components and even the chips etc. Literally its a little mess up because the manufacturers are giving us a high power opamp and asking us to make the desired circuits according to our needs.

Yes.. Its pure freedom. But i feel like its complicated. Because not all of us are equally skilled. And for those who dont know how to use freedom properly, they will surely mess it up . This is the sole reason i want to start a thread like this.

Most of us have experiences with chips that does require less than 10 external components, yet can deliver HiFi quality audio with less than 1% thd at maximum power. And are so simple to build. I want you all to share this to all members. So lets share details of similar chips.

Conditions are:-

1) The original amplifier circuit must contain the least amount of components , in a maximum upto 10 components.
2) class AB or Class D ( standalone)
3) maximum thd should be less than 1% at full load.
4) simplest circuit, which can even be done with out a pcb.
5) circuits with least value capacitors ( ofcourse we can have heavy ones in power section, but what i mean here is specifically for lower value dc blocking capacitors in speaker lines)
6) low or no pop noises on turn on and turn off ( one of the worst problems with most op-amps)
7) ofcourse it should be a " NON OP-AMP CIRCUIT" with out the hassles of all calculations that comes with OP-AMPS.
8)chips extra features like mute/standby /digital - analog controls are most welcome.

I will provide you with such a chip . Take a look at it.. And then you all will get the idea of what this is all about. After that, you can share your knowledge . post the datasheet link with just simple descriptios of o/p power, channels , thd value at maximum power, and operating voltage. I will update this opening post with those details you post, so that members can have a quick look.
Thank you all.


Take this example.

TDA 7560
Power output and channels - 4*51 watts @ 4ohms - 4*80 watts @ 2 ohms
Thd- 0.03% @ 15 w / 4ohms.
Operating voltage - 8-18 vdc.
Extra features - stand by, mute and auto mute, fixed gain 26db, o/p short circuit protecton, reversed battery protection.

TDA7560 Hi-fi quad BTL output power amplifier with HDS/offset detection, stand-by and mute - STMicroelectronics
 

johnr66

Member
2009-03-05 1:55 pm
A lot of us do it for the challenge. It is not always straightforward or easy. Hobbies must offer some challenge and gratification or they become boring.

ANY chip can oscillate or distort due to poor layout. Some effort must be made to understand why this happens.

To reply to some of your conditions:

1) The circuit must have all the parts necessary to function properly. For example, the car audio BTL IC you quote, I would add a low pass filter to all the input lines to keep RF and some HF feedback out of the amp. That is 8 components right there.

3) Any amplifier will begin to distort when it starts clipping. An amplifier that is producing 1% THD is likely just starting to clip, so your "full load" specification is a matter of perspective. I prefer to rate an amplifier at a point before clipping begins. If an amplifier is at 1% THD when there is no sign of clipping present has other serious issues, such as poor ground layout.

5) No this won't work. If you put too small of capacitance in the output for DC blocking, you lose bass response. It is the physical nature of how this stuff works.

6) No pop noises is ideal, but it doesn't bother me unless it is excessive.

7) Some of us prefer having the negative feedback available for setting the gain. The calculation is simple. ICs with the non op amp design means it has the gain fixed by having the feedback internal. I find some fixed gain ICs unusable because gain is set too high and there is a lot of hiss especially with high sensitivity speakers.

The TDA7560 may work for you but it is not for me. First, my favorite speakers are 8 ohm and at the low voltages these operate, you only get 7 or 8 clean watts before clipping. It has two extra channels I don't need. An LM1875 is pretty simple and can give me 25 clean watts into 8 ohms and probably with better fidelity. To each his own.
 
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Building your minimalist circuit is the best way to learn the pitfalls of such a design philosophy. You will learn the minimum number of components required for it to work, and the minimum number of components required for it to work correctly. I highly recommend it.

The LM1875 recommended is a great way to start. To make it even simpler,I think you can still get boards for it from chipamp.com.
 
Hi to u all.I had a problem with an amplifier which i built using lm1875 and would not work properly inspite of the fine layout pcb obtained from a magazine.Following recommendations from other diyers,i made some changes to the circuit but to no avail,the chips overheated and would only deliver sound at low supply voltages which was n't normal.After checking everything carefully,i came to the conclusion that the ics themselves were faulty.In fact they were! A new set worked fine and didn't have any problems although both sets came from the same chinese manufacturer. I am puzzled why one set worked properly while the other one didn't although both were purchased new.
 

johnr66

Member
2009-03-05 1:55 pm
Hi to u all.I had a problem with an amplifier which i built using lm1875 and would not work properly inspite of the fine layout pcb obtained from a magazine.Following recommendations from other diyers,i made some changes to the circuit but to no avail,the chips overheated and would only deliver sound at low supply voltages which was n't normal.After checking everything carefully,i came to the conclusion that the ics themselves were faulty.In fact they were! A new set worked fine and didn't have any problems although both sets came from the same chinese manufacturer. I am puzzled why one set worked properly while the other one didn't although both were purchased new.

They were probably counterfeit. I bought a TDA2004 from a Chinese vendor and it came to me defective right out of the pack. Swapped in an authentic one and the circuit was fine.
 
Brothers.. This is not any offence or lack of respect to any of you or your works.. I am an EE engineer and works as service engineer in an audio systems company. I deal with lots of power amplifiers from bhringer, dyanacord,and various other devices from japan and germany. And we even have our own vircuits.. All of these are mostly MOSFETs/transistors/class d system.. Just because they are all used for PA or similar works. And hence these are mostly 700-3000 watts rms types.. And i deal with these things.. So i dont have any problems in dealing with simple op amps.

But this is not about me or audiophiles like you people.. This is about helping newcomers. Not all of us have good skills in building and trouble shooting. Some doesn't even know how to make a clean solder blob.
But that doesn't mean that they deserves low reputation or have to leave with low audio quality amps. This is about less job and good results.. Belive me.. I know how hard it is for a beginner... I still rember how hard it was for me to build a tda810 based amp, which was my first amp, before 16 years.

So i request you people can join me to help some newbies.
 
So i request you people can join me to help some newbies.
Using chipamps properly is a start.
But "properly" requires AC coupled and Input Filters and local decoupling of supply rails and Thiele Output Network.
That automatically commits the Beginner to using many components.
It's not just about picking an adequately good chipamp, some are just incapable of adequate performance. It's about getting the chipamp to perform as intended by the Builder.

It's all in the the many Threads that repeatedly tell them that low component count does not guarantee good performance.
 
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Arty

Member
2011-02-24 5:04 pm
number of components is a tradeoff.. there is a point when throwing more at it will not yield anything at all.


a list of good starter chips is okay, stuff that is known to be easy to build for the beginner.
but number of external components minimum is .. not a factor.

single supply, not that may be intresting as its quite easy to rig those up to some cheap batteris for testing, and i would prefer that for beginner projects. fixed gain while not ideal, but surely .. least that can't be funked up, so i would welcome that onboard too.
protection features, neato. want it. all of it.
soldering wise, something with big leads and big spacing instead of some "surface" stuff. less pain for soldering.

and there are a mirage of chips that fit this bill.
all of them are decent beginner projects, and nowdays most of them stand up well quality wise too. as you don't need 3 trillion "whats" to blow your neighbors hair away.
anything that can do 10 watt with less than 1% thd is powerfull enough.
and many of these chips can do a lot more than that.

car radio chips fit these bills.
ruged, fixed gain, bridgeable for more power, multi channel, not picky about layout, cheap, nice to solder, has a lot of protection features, and decent sound quality, single supply operation, not toopicky about powersupply quality.
what else you need for a beginner project...
 
Using chipamps properly is a start.
But "properly" requires AC coupled and Input Filters and local decoupling of supply rails and Thiele Output Network.

When using popular "hi-fi" chips like 1875 and 3886, this is unavoidable. This is the minimalist circuit.

DC coupling requires servo, and is not beginner friendly. For audio it never seemed worthwhile to me. The correct capacitors used properly are for all practical purposes transparent.
 

mrWagner

Member
2006-10-27 1:34 pm
The problem as already starts to turn out is that the more you experience the more parts you start to install.
The minimalist gainclones doesn't have much coupling and no protections at all.
I also built my first one like that. But than you have the risk of destroying your amp or your speaker. And then you build in more and more protection. Like the DC coupling, then servo, then clipping prot, then DC out prot and ...
And there is the argue if you need these or you will takes risks. If someone managed to kill a speaker, then the protections are a MUST. But if not, then these are just good to have stuff. But if you do use protections, then the 8-10 part amplifier is impossible.
 
.............The minimalist gainclones doesn't have much coupling and no protections at all.............. then the 8-10 part amplifier is impossible.
Local supply rail decoupling adds 4 components, input filters adds 4 components, Output Thiele Network adds 4 or 6 components, diode protections rail to rail and rail to output adds 4 components. DC block on NFB adds 1 component. That's 17 extra components and we don't have DC detect/protect, nor soft start, nor etc......
 
start defining what makes HI-FI.
That's noble. You want a non-moving target.

I don't think that we can use that language. Instead, we have to ask two questions similar to these:

What do you require your amplifier to do, such as what aspects do you like best, and please be specific?
AND
What do you require your amplifier doesn't do, such as what aspects do you dislike most, and please be specific?

Commonalities between many responses, has a fair chance at answering your question.

I'm not quite organized enough for directing that particular task. My house has two "everything drawers" so that disqualifies me straightaway.