Good evening everybody,
I'm working since a long time on a high power, high efficient and modular Class D Amplifier from 50 to 300W per channel with DSP, Bluetooth and maybe more ;-)
Based on a already good working Texas Instruments TPA3251 amplifier chip, I renewed my design to also fit for the brand new TPA3255 chip!
Some key features:
+ One design for TPA3255, TPA3251 or TPA3245 chip (depends on the power you need)
+ able to use Coilcraft MA5173 or MLC1565 output inductors
+ onboard µC for direct control
+ Display connector for character or pixel LCD/OLED Displays!
+ GPIO connector for buttons, potentiometers or encoders (for volume or menu control)
+ you will be able to decide between several AddOn Modules for DSP, Bluetooth, DAB+ Radio, SPDIF... very flexible due different modules
+ direct soundcontrol via Analog Devices Sigma Studio (for licence reasons: just for developers)
+ made for mobile use, very low power consumption
+ in addition with my powermodule and battery chargers: able to use with nearly every batterie available on market with always best efficiency!!!
+ I invested a lot of knowledge and experience in pcb design to achive the best possible sound and performance grade
+ you're able to input a external I2S digital audio source to the DSP & Bluetooth Board with almost every sampling rate! (ASRC is onboard!)
I will order my first PCBs at the end of this week. For now I'm in the end of designing and planning phase.
I'm ready and open for your feedback and support.
Thanks
Regards and greetings from Germany!
Bernhard Wächter
I'm working since a long time on a high power, high efficient and modular Class D Amplifier from 50 to 300W per channel with DSP, Bluetooth and maybe more ;-)
Based on a already good working Texas Instruments TPA3251 amplifier chip, I renewed my design to also fit for the brand new TPA3255 chip!
Some key features:
+ One design for TPA3255, TPA3251 or TPA3245 chip (depends on the power you need)
+ able to use Coilcraft MA5173 or MLC1565 output inductors
+ onboard µC for direct control
+ Display connector for character or pixel LCD/OLED Displays!
+ GPIO connector for buttons, potentiometers or encoders (for volume or menu control)
+ you will be able to decide between several AddOn Modules for DSP, Bluetooth, DAB+ Radio, SPDIF... very flexible due different modules
+ direct soundcontrol via Analog Devices Sigma Studio (for licence reasons: just for developers)
+ made for mobile use, very low power consumption
+ in addition with my powermodule and battery chargers: able to use with nearly every batterie available on market with always best efficiency!!!
+ I invested a lot of knowledge and experience in pcb design to achive the best possible sound and performance grade
+ you're able to input a external I2S digital audio source to the DSP & Bluetooth Board with almost every sampling rate! (ASRC is onboard!)
I will order my first PCBs at the end of this week. For now I'm in the end of designing and planning phase.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I'm ready and open for your feedback and support.
Thanks
Regards and greetings from Germany!
Bernhard Wächter
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... one step closer
... some update in pcb design.
Deadline comes closer and closer
Btw: Amp will fit into a Fischer-Elektronik aluminium housing*
(*) not with Bluetooth module.
... some update in pcb design.
Deadline comes closer and closer
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Btw: Amp will fit into a Fischer-Elektronik aluminium housing*
(*) not with Bluetooth module.
Not really commercial, but I always try to set myself a deadline on every project.
But in fact yes, I also will sell these boards (or fully assembled amplifiers).
First of all: Thank you for compliment! In fact yes, I thought about using a codec for AD / DA conversion but then I did some tests with the onboard ADAU1701 converters and was pretty satisfied with them. Of course it's not the high grade sound quality but for a mobile application, where the main view is on efficiency, it's a quite perfect conversion performance.
But, here the main advantage of this design comes: This amp is not based on one DSP chip, it's about a card what can be changed for several needs. So if you want to use a bigger DSP... no problem! You want a Bluetooth sink? No problem! DAB+ radio? Hifi grade SPDIF receiver or AD/DA converter? No problem! ;-)
For the first run it will be a 4 Layer design with a ADAU1701 DSP, a WT32iA Bluetooth module and a SRC4193 sampling rate converter. On the back of the card will be a connector for a external I2S Source (via H.FL connectors).
I guess this combination covers a lot of applications, specially in mobile usage.
I designed a special piece of aluminum for transfering the heat of the chip to the housing. All of my previous tests were just based on a piece of aluminum, not even a real heatsink and it was prefectly working (after some time and many experiments ... haha)
The TPA3255 samples just arrived last week, I didn't even have time to unpack them. But I designed a Buck/Boost converter with variable output (so I also can go down to 15V PVDD for reducing power consumption) and already tested it on a 350W DC load @ 48V. Unfortunately my lab supply is just able to deliver 15Amps so my first tests are based on 24V input. I will try to use my lab supplies in parallel mode to give you some information about 12V usage. But for now, this is not my main goal and I would not suggest to use a 12V battery for such a high power. My suggestion would be a 33,3V li-ion pack. But this is another topic.
Thanks for the input. Well, 12V SLA (or better 2x12V in series) is still common due to price and "noob-proof" handling. Using a 9s Li-Ion battery pack needs a BMS minimum to be charged easily (buck/boost prefered). Another concern is the DC-resistance + ESR of the pack. While SLA ESR is really low, even for two cells, Li-Ion is probably not. (As you may know i guess.)
For the easiness of calculaction lets assume 24V system input voltage. (and no connection resistance)
2x12V SLA (Multipower 12V 7.2Ah): 19mR each = 38mR in series 172Wh 22€/each 44€/pack
Data Soure: http://www.accu-profi.de/doku/mp7%202-12%20%2010-04.pdf
7s Li-Ion (LG18650HG2 3.6V 3Ah) -> 25.2V: 20mR each: 140mR in series 75.6Wh
Data source: http://keeppower.com.ua/download/2015-06/datasheet-LG_INR18650HG2-1.pdf
So we need to go for 7s3p to get down to 35mR pack ESR and have 226.8Wh then. At 4.50€/cell this adds up to 94.50€. (+BMS costs)
Due to more connections between cells, these values will also add up.
Im really interested in this buck/post power supply you mentioned.
And this works for 350Wrms (30-35W dissipation) output continuously with the Fischer? Cool.
Regards.
For the easiness of calculaction lets assume 24V system input voltage. (and no connection resistance)
2x12V SLA (Multipower 12V 7.2Ah): 19mR each = 38mR in series 172Wh 22€/each 44€/pack
Data Soure: http://www.accu-profi.de/doku/mp7%202-12%20%2010-04.pdf
7s Li-Ion (LG18650HG2 3.6V 3Ah) -> 25.2V: 20mR each: 140mR in series 75.6Wh
Data source: http://keeppower.com.ua/download/2015-06/datasheet-LG_INR18650HG2-1.pdf
So we need to go for 7s3p to get down to 35mR pack ESR and have 226.8Wh then. At 4.50€/cell this adds up to 94.50€. (+BMS costs)
Due to more connections between cells, these values will also add up.
Im really interested in this buck/post power supply you mentioned.
And this works for 350Wrms (30-35W dissipation) output continuously with the Fischer? Cool.
Regards.
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I think there are more points to consider in choosing a battery pack for your application. ESR is one point... but yes Li-ion needs more knowledge and care in the design process.
I will come back to this soon. I'm on holidays next week with my girlfriend which has a much higher priority
The fisher housing is not the perfect choice if you want to use the amplifier at full power over a long time. In this case a ventilated housing is needed.
But in fact I'm able to get away the heat from the chip with my construction, this is what I wanted to say ;-) Of course you need to choose a proper heatsink for the application you need. You also need to decide which chip or inductor you will use and in most cases the fischer housing with the heatsink on one side is a perfect match.
But with my design you are free to choose a heatsink you require.
It's already burning under my nails to finally build this amp and do further tests with it
Regards
I will come back to this soon. I'm on holidays next week with my girlfriend which has a much higher priority
And this works for 350Wrms (30-35W dissipation) output continuously with the Fischer? Cool.
The fisher housing is not the perfect choice if you want to use the amplifier at full power over a long time. In this case a ventilated housing is needed.
But in fact I'm able to get away the heat from the chip with my construction, this is what I wanted to say ;-) Of course you need to choose a proper heatsink for the application you need. You also need to decide which chip or inductor you will use and in most cases the fischer housing with the heatsink on one side is a perfect match.
But with my design you are free to choose a heatsink you require.
It's already burning under my nails to finally build this amp and do further tests with it
Regards
DSP can run on 48/96 or 192kHz. You can set this via software.
The ASRC works as slave on both sides. So the ADAU is master and the external input must be master, too. Clock for the ASRC is 24.576MHz.
Hmm would be possible by using the BYPASS pin of the SRC. But then, the ADAU needs to run as slave... Only a good idea if your external clock source is stable and always present.
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This is not true for the ADC/DAC sections within the ADAU. They get filled with pseudodata. ADC/DAC performance is always 48kHz.
Why?
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Ok yes you're right.
Because the SRC routes all data from input to output in bypass mode, for this reason the device connected to the output of SRC must be a slave. Or am I wrong?
Ah... moment... I was talking about that ADAU is working as a sink.
Yes ... but it's actually nice to get some feedback from you guys here to figure which versions of DSP Cards will make sense in the future.
First impressions
Good evening,
my pcbs arrived and I started assembling the amplifier.
I also chose a name for this amplifier:
Hyper Converged Sound Amplifier - HCSA
Hyper converged because it's kinda a all-in-one board and all systems like control, display driver, sound processor, ... and of course the amp are on one board. All you need is a power supply and a housing.
But now back to something more interesting... the pictures:
The fully assembled amplifier:
... closer view to solder paste, still not soldered:
The DSP & Bluetooth AddOn Card:
HCSA on a piece of aluminium and ISP / LogicAnalyzer / USBi Clone connected.
First of all the good news:
- the amplifier works and I already listened music with it
- DSP, µC, anti-plopp protection and bluetooth seem to work, too (didn't test all fully, yet)
... then the "bad" news:
- A really stupid mistake happend in pcb design: the connector for the addon card is inverted I realized it after I already soldered it to the amplifiers main board. It took me a while to unsolder and flip it. This will be fixed in the next board revision!
But (for now) this is the only problem I found
Even the bluetooth module is happy and already talking on the UART bus:
I will publish some more information soon!!
Best regards from Germany,
Bernhard
Good evening,
my pcbs arrived and I started assembling the amplifier.
I also chose a name for this amplifier:
Hyper Converged Sound Amplifier - HCSA
Hyper converged because it's kinda a all-in-one board and all systems like control, display driver, sound processor, ... and of course the amp are on one board. All you need is a power supply and a housing.
But now back to something more interesting... the pictures:
The fully assembled amplifier:
An externally hosted image should be here but it was not working when we last tested it.
... closer view to solder paste, still not soldered:
An externally hosted image should be here but it was not working when we last tested it.
The DSP & Bluetooth AddOn Card:
An externally hosted image should be here but it was not working when we last tested it.
HCSA on a piece of aluminium and ISP / LogicAnalyzer / USBi Clone connected.
An externally hosted image should be here but it was not working when we last tested it.
First of all the good news:
- the amplifier works and I already listened music with it
- DSP, µC, anti-plopp protection and bluetooth seem to work, too (didn't test all fully, yet)
... then the "bad" news:
- A really stupid mistake happend in pcb design: the connector for the addon card is inverted
I realized it after I already soldered it to the amplifiers main board. It took me a while to unsolder and flip it. This will be fixed in the next board revision!But (for now) this is the only problem I found
Even the bluetooth module is happy and already talking on the UART bus:
An externally hosted image should be here but it was not working when we last tested it.
I will publish some more information soon!!
Best regards from Germany,
Bernhard
Last edited:
I continued working on this project and added the firmware for the bluetooth module. Works pretty fine for now
I2S sampling rate out of BT module is 44k1, the conversion to 48k works and the DSP makes a DA-conversion to feed the amplifier.
Everything works as expected.
Screenshot of I2S bus out of bluetooth module:
UFL connectors for external I2S input:
Power consumption with active bluetooth connection and working sampling rate conversion: ~2.9Watts @ 20V (143mA)
~5.5Watts @ 48V (115mA)
Regards
Bernhard
I2S sampling rate out of BT module is 44k1, the conversion to 48k works and the DSP makes a DA-conversion to feed the amplifier.
Everything works as expected.
Screenshot of I2S bus out of bluetooth module:
An externally hosted image should be here but it was not working when we last tested it.
UFL connectors for external I2S input:
An externally hosted image should be here but it was not working when we last tested it.
Power consumption with active bluetooth connection and working sampling rate conversion: ~2.9Watts @ 20V (143mA)
An externally hosted image should be here but it was not working when we last tested it.
~5.5Watts @ 48V (115mA)
An externally hosted image should be here but it was not working when we last tested it.
Regards
Bernhard
May i ask why you use that big inductor for the buck converter? Isn't this only powering AVCC (TPA32XX 12V) and the analog frontend?
What switcher IC are you using on the "left side"? The one with the 2R2 inductor.
Regarding the outputs with the MLC1565 inductors, is this meant for high frequency speakers?
Regards.
What switcher IC are you using on the "left side"? The one with the 2R2 inductor.
Regarding the outputs with the MLC1565 inductors, is this meant for high frequency speakers?
Regards.
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