Hi there!
I own CSR8645 bluetooth module with HT6872 amplifier which gives me 3W power after delivering 5V, however this is differential output and I need to convert it to single ended. I know that directly from CSR you can do this with some kind of AMP, however how am I supposed to figure it out with already amplified signal? Is for example converter like this going to work?
Best regards!
I own CSR8645 bluetooth module with HT6872 amplifier which gives me 3W power after delivering 5V, however this is differential output and I need to convert it to single ended. I know that directly from CSR you can do this with some kind of AMP, however how am I supposed to figure it out with already amplified signal? Is for example converter like this going to work?
Best regards!
Hmm, I'm trying to build simple bluetooth extension to my cars stock audio which I would like to connect with AUX input (typical single-ended audio). However, radios AUX has quieter audio volume - that's why I need small amp to aign all audio sources.
It seems that 3W from bluetooths moudle amp is enough to have satisfying result. Only obstacle is that HT6872 amplifier, as I said before, gives me differential audio. I need to convert this signal to standard jack pinout in the easiest way.
Thank you for response.
It seems that 3W from bluetooths moudle amp is enough to have satisfying result. Only obstacle is that HT6872 amplifier, as I said before, gives me differential audio. I need to convert this signal to standard jack pinout in the easiest way.
Thank you for response.
And why exactly are you using (or why do you need to use) a power amplifier, to feed the Aux input (line-level) of your car head unit?
It's more complicated: head unit doesn't have typical AUX in, it has special CD changer connector. I built emulator which "cheats" radio that CD changer has been connected and allows me to send signal to pins L, R and GND. However, this signal originally was probably amplified by usual CD changer because connecting phone directly, ends with very low volume - to get same level as with normal radio signal or CD, you need to raise it twice.
When I connected this amplifier (with just one negative leg and L+, R+ of differential output) I received perfect sound volume but it isn't a solution. This is the reason I think.
When I connected this amplifier (with just one negative leg and L+, R+ of differential output) I received perfect sound volume but it isn't a solution. This is the reason I think.
Ever heard of (or considered) something that's called a preamp / preamplifier? THAT is what you actually need.
Khron is correct. You don't want a Class-D power amp here. You need a line boost. Basically a pre-amplifier.
That's cool, thanks! I must say I heard about pre-amp but didn't think about using it here.
So how am I supposed do do this? I want to use bluetooth module, connect it with AUX and stream music from my phone. I guees I can't use theese HT6872s?
So how am I supposed do do this? I want to use bluetooth module, connect it with AUX and stream music from my phone. I guees I can't use theese HT6872s?
I do not agree with any of the prior posts.
Looking at your CSR8645 board, I think the simplest way is to connect LP (left +) to the left channel, RP (right +) to the right channel and GND to ground. You will not be using LN or RN which may give a little imbalance to the differential signal (not that you would care very much) and your gain will be half of what it otherwise would be, but this should work fine (or instead of connecting LP and RP you could ...assuming everything is actually differential, connect LN and RN and not use LP and RP).
The diagram in the description shows LP and RP connected to L and R, but shows LN instead of GND (ground) connected to ground (the sleeve on the 3.5mm TRS connector). I would tend to not believe this since the back of the board shows LN and RN coming from separate opamp outputs which makes me guess that they are actually differential. Go figure, nice quality if true. So I'd try GND to ground not LN (but it in theory could be the same depending on the circuit of which I have no idea). But we can I think be pretty confident that LP and NP are + and + L and R and that is all you need to wire up along with ground to use this in a SE manner.
5V to power this up should be fine - for a car head amp CD input what would you need- only 1-2 volts of signal?
Or if you want to actually convert balanced to single ended use an INA134 (or INA2134 with 2 inputs) chip which is built for this purpose. Or an audio transformer for conversion. These can be pretty small.
Looking at your CSR8645 board, I think the simplest way is to connect LP (left +) to the left channel, RP (right +) to the right channel and GND to ground. You will not be using LN or RN which may give a little imbalance to the differential signal (not that you would care very much) and your gain will be half of what it otherwise would be, but this should work fine (or instead of connecting LP and RP you could ...assuming everything is actually differential, connect LN and RN and not use LP and RP).
The diagram in the description shows LP and RP connected to L and R, but shows LN instead of GND (ground) connected to ground (the sleeve on the 3.5mm TRS connector). I would tend to not believe this since the back of the board shows LN and RN coming from separate opamp outputs which makes me guess that they are actually differential. Go figure, nice quality if true. So I'd try GND to ground not LN (but it in theory could be the same depending on the circuit of which I have no idea). But we can I think be pretty confident that LP and NP are + and + L and R and that is all you need to wire up along with ground to use this in a SE manner.
5V to power this up should be fine - for a car head amp CD input what would you need- only 1-2 volts of signal?
Or if you want to actually convert balanced to single ended use an INA134 (or INA2134 with 2 inputs) chip which is built for this purpose. Or an audio transformer for conversion. These can be pretty small.
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He's not talking about using the outputs of the CSR8645. He bought a CSR8645 based module with an integrated Class-D amplifier. He was asking about feeding the amplifier outputs into his HU AUX input, which is a bad idea.
Yes I see the module under the blue board, its not a bad idea unless it doesn't work. I think it can be done as I described.
@lgreen
I think that seller mixed images on the auction. My module has RP, RN, LP, LN and you cannot connect it with typical TRS onnector. Single-ended output is available with more expensive board, powered with 12V and it's shown in the picture.
@Everyone
I understand why it's not recommended to connect amp to amp. This class D amplifier could make some distorsions for example during playback and it's one of the reasons not to do this here.
I need to buy another CSR module, without any amp, and then make pre-amp with similar performance which will be able to give me standard, single ended signal. Am I right?
I think that seller mixed images on the auction. My module has RP, RN, LP, LN and you cannot connect it with typical TRS onnector. Single-ended output is available with more expensive board, powered with 12V and it's shown in the picture.
@Everyone
I understand why it's not recommended to connect amp to amp. This class D amplifier could make some distorsions for example during playback and it's one of the reasons not to do this here.
I need to buy another CSR module, without any amp, and then make pre-amp with similar performance which will be able to give me standard, single ended signal. Am I right?
The amplifiers on your module have full-bridge outputs. This is why it has RN and LN outputs and not a single ground. Full-bridge gives higher output power from a single supply compared to half-bridge/single-ended.
This is the module you should have bought... CSR8645 APT
It has a TPA6132 headphone amplifier IC instead of the Class-D amps. You probably won't need any more output voltage than the TPA6132 provides.
This is the module you should have bought... CSR8645 APT
It has a TPA6132 headphone amplifier IC instead of the Class-D amps. You probably won't need any more output voltage than the TPA6132 provides.
Hmm, so TPA5132 would work as a preamp here? How am I suposed to interpret values of this module? I mean, not burning anything in head unit or having to weak signal. What is... I don't know, RMS of this module? Or any other parameter which could tell me volume boost during playback?
Is this same preamp as suggested but without bluetooth?
Is this same preamp as suggested but without bluetooth?
Line level signals aren't measured in watts, they're measured in volts. The TPA6132 will output a max signal a little over 1.1Vrms. That's about what a typical smartphone will do. If your phones headphone output will drive the HU loud enough then the TPA6132 will as well.
Yes, that board is the same thing minus Bluetooth. You could try cobbling the two boards together but that seems like more trouble than it's worth.
Yes, that board is the same thing minus Bluetooth. You could try cobbling the two boards together but that seems like more trouble than it's worth.
So the problem still remains because my phone gives me about twice lower volume than other available inputs. I need something with 2Vrms, am I right?
Btw. Thank you for filling me with so helpful answers, it really helps!
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