Inverting Inputs of a Chipamp

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Carel_Integrated

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Hi everyone. I was wondering if it is possible to connect a chipamp such as the TA8205AH to the same PSU that is powering the source. Let's say you connect the amp to a PC's 12V rail and you connect the Inputs to the soundcard's output (R, L & GND) - then you'll actually be shorting the V- input to the ground, right? So is there a way to connect this chip on the same power source as the input? With what circuit can this be done or can someone explain me what can be done and what will be the best option because I'm stuck on this one. It should be possible because the use these chips in car radios and the car has only one battery to power both the radio and the amp (all-inside-one unit). Help or guidance would be appreciated.



Thank You
 
hmm, That's what I've asked. I don't know how and I can't find a circuit diagram or anything similar to explain to me how it should be done and how it works.
 
Carel_Integrated said:
hmm, That's what I've asked. I don't know how and I can't find a circuit diagram or anything similar to explain to me how it should be done and how it works.
Click to expand...

Read the datasheet, in fact the only diagram is for single supply use as it's a car radio chip, so no split supply available.
 
Yes, I have read the datasheet because I've already built the amp and it's working fine. The only problem I have is the inverting input that gets shorted to GND... Maybe I can use a circuit that does the opposite that an LM358N / LM2904 does. This chip converts the inverting audio to a positive only output. I don't know what chip can be used for the opposite and I don't even know if the LM358 will work for audio. Also, the PSU isn't the problem, it's the audio source because the amp uses only a single supply and not a center tapped or dual supply. I also don't believe that anyone understands what I'm saying because I don't know the technical terms for this problem. I've never really built a lot of amps before, but I have built an EEPROM and SPI programmer before with my own diagrams, etc. I think my next DIY would be an LPC programmer. Inverting amps just simply give the best audio. Their audio sounds great and that's why expensive A2DP bluetooth receivers's audio sound great too.

I have a cheapy bluetooth A2DP {Bluetooth Advanced Audio - Stereo} that costed me about $20 and it's audio sucked. It has inverting outputs so I couldn't solder an ordinary (R, L, GND) stereo jack to the receiver as each headphone is on i'ts own inverting channel. L+, L-, R+ & R-. Connecting R- to L- would cause it to play in mono. The Receiver is actually good quality as the chip is made by CSR. I desoldered the earhones that came with it and soldered a pair of original Philips earphones to it and now I believe I won't get better sound quality anywhere else. It even sounds better than the original $100 costing Nokia A2DP receivers. I believe I can connect a stereo jack If I use an LM358 chip for this? I don't know if the LM358 is suited for audio and how it will affect the sound quality. Is there maybe something I can do for the Bluetooth Headset {it has inverting outputs}?
 

I'm sorry - I don't have the faintest idea what you're on about - the inverting inputs on the chip don't get shorted to ground, where does it show that on the datasheet?.

Post your circuit here so we can see what you're on about.
 
That's correct - you won't find that on the datasheet??? I don't think you completely understand me. The V- and V+ are the inverting inputs and should NEVER be connected to the ground. My problem is I'm using the same PSU for the application supplying the audio input {the audio source doesn't have inverting outputs} and the amp itself {which has inverting inputs}. I really don't know how to say this differently... I can't connect the source {which has a R+, L+ & a GND} to an inverting amp that uses the same PSU or battery as the Audio source {cd-Player}. If I connect the GND of the Audio source {the GND of the Audio Source is connected to a battery's GND pole} to the V- of the AMP, then indirectly I'm shorting the V- of the amp to the GND. Savvy?

I'll draw a picture and post it... Maybe it will be clearer than my words as I'm not actually English.
 
The stereo signals connect to the input capacitors of the amplifier and the ground of the stereo signals connects to the ground of the amplifier.
The inverting inputs of the amplifier are connected to ground with capacitors so their DC voltages are not changed.
 
audioguru said:
The stereo signals connect to the input capacitors of the amplifier and the ground of the stereo signals connects to the ground of the amplifier.
Click to expand...
I have connected the stereo signals to the 2x C1 capacitors in the schematic, that's correct {IN1 and IN2 in schematic}. I can't connect the GND from the audio {which is the same as the GND of the PSU + amp} to the GND of the amp - it will send 6V to the speakers.

audioguru said:
The inverting inputs of the amplifier are connected to ground with capacitors so their DC voltages are not changed.
Click to expand...
Yes, there are capacitors on NF1 & NF2 + GND, but I can't connect the GND from the CD-Player to the amp's GND because it sends 6V to my speakers.

In the previous picture I've accidentally connected the GND of the audio to the Ripple of the amp. Here's a new picture.
UPDATE: **broken link removed**
 
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As for the bluetooth with Inverting outputs - how can I connect it to a normal stereo input jack? By using an op-amp? What op-amps are cheap and good for audio?
 
Carel_Integrated said:
Yes, there are capacitors on NF1 & NF2 + GND, but I can't connect the GND from the CD-Player to the amp's GND because it sends 6V to my speakers.
Click to expand...

Why would you want to? - the datasheet clearly shows how to use the IC - just follow that, you only connect to the two inputs and the common ground, you don't connect anything to the inverting inputs except the two capacitors shown (why would you think you should?).
 
I think you're used to the LM3886 type of amp which uses a center tapped transformer. It doesn't support bi-directional audio, so the Bass isn't so good, it's just Good, not Excelent. The way you want me to connect the TA8205AH amp won't work. I've tested it already and I can confirm the GND of the amp is not for audio, it will cause the amp to play the speaker in only one direction. The speaker is also not connected to the GND. Channel 1 uses IN1 and NF1 for audio input and OUT1 & OUT2 for the output. I don't see the part in the datasheet saying I should connect the amp to the GND. I'm actually using the amp like the datasheet says. IN1 + NF1 for input.

Perhaps you can tell me where in the datasheet it says that I should use the common ground, because I can't see it. Page no?
 
I've done another test to confirm.

Test 1:
Connect the IN1 Input to the GND {according to what you say the datasheet say, the input signal is now terminated so NOTHING should go to the speaker, but the opposite happens, meaning the GND isn't on of the inputs} - the amp sends 6V to the speaker.

Test 2:
Connect the IN1 Input to the NF1 {according to what I see in the datasheet - the signal is now terminated and the amp sends 0V to the speaker}. Connecting the Audio to the IN1 and NF1 pins gives excelent Bi-Directional Audio. The V- (NF1) is lower than GND. The V+ (IN1) is higher than GND. They should be used for audio input.

The datasheet says: Bipolar Linear Integrated Circuit
If I use GND for anything them it will backfire.
 
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For the third or fourth time - USE THE CIRCUIT AS SHOWN ON THE DATASHEET - that's all that's needed, and your silly pointless schemes probably wouldn't work anyway.
 
For the 100th time. You don't understand what I'm asking. I've already built the amp, I just don't know how to connect it's inputs to the CD-Player's output. there's nothing in the diagram on how to do that...
 
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Carel_Integrated said:
For the 100th time. You don't understand what I'm asking. I've already built the amp, I just don't know how to connect it's inputs to the CD-Player's output. there's nothing in the diagram on how to do that...
Click to expand...

Of course there is - page 7/11 on the datasheet - two C1 capacitors at the left, the inputs go in there.You obviously need a common ground as well, and that would (again obviously) be pins 5, 13, 14 and tab.
 
Please attach you schematic to your reply here instead of over at Mediafire who takes all day to wake up and it is full of ads.

The ground from your CD player must be connected to the ground of the power amplifier, not to the NF1 and NF2 inputs.
All the inputs of the power amplifier have capacitors because they are all at +6VDC. All the outputs are also at +6VDC then the speakers have 0V across them.

Why do you talk about V-? There is no V-. The amplifier is powered from +12V and ground.
 
Repeat: NF1 and NF2 are not inputs. They are connected to ground with capacitors so that the amplifier has a DC gain of 1 and as much AC gain as shown on the datasheet.
 
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