My new TPA325x DSP/Bluetooth/X Amplifier made for mobile Application - Page 8

mantabernd · 8th March 2017, 11:37 PM

Quote:

Originally Posted by doctormord

Define "low noise".

A gain of 26dB is a bit high for a normal smartphone source, is it not? (At 1Vrms output)

Sorry it's a gain of 15.7dB, not 20dB like I wrote before.

You also need to add around 9dB gain because of post filter feedback configuration. Regular Smartphones have a output level between 0.7V - 1V(rms).

I needed to fit my gain chain to the DSP which has a output of 0.9V(rms) but in fact I prefer to not go obove 0.7V(rms).

Low noise for me is a noisefloor of -100dB and better.

I will make some measurments and post them tomorrow evening.

mantabernd · 11:10 PM

Attached the measurment of preamp.

My setup

Sig Generator ----------------------------------------> DSP ----------------------------------------> Preamp Out
0.46V/0.65V(rms/pkpk) ----------------------------- Gain: 0dB ------------------------------------ 3.28V/4.634V(rms/pkpk)

This ends up in a gain of 17dB just for the preamp stage.

I was a bit confused first because the gain must be 15.7dB but then I realized that I took a bit different resistor values as in schematics

CH1 is measured at the output of DSP, CH2 at the output of Preamp.

FFT Plot is for CH2.

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3eaudio · 10th March 2017, 12:31 AM

Quote:

Originally Posted by RobFreak

I know the frustration! Perhaps you should consider a bigger batch if you are confident doing that? I work with semi-massproduction of electronics, so i know the feeling of prices not being what they should be..

is the BT module chipset from CSR? APTX?

another question is that there are also many cost effective material from china,but you need some time to source.

mantabernd · 10th March 2017, 09:24 AM

Quote:

Originally Posted by 3eaudio

is the BT module chipset from CSR? APTX?

BT module is from bluegiga:

WT32I-A-AI6-APTX

Quote:

another question is that there are also many cost effective material from china,but you need some time to source.

Is this a question or a fact? What exactly do you mean this this?

mantabernd · 10th March 2017, 11:44 PM

Some more pics and measurments:

FFT Ampout 1W@4Ohms

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THD+N 0,009% | 10W@4Ohms from a 162mV(rms) source

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THD+N 0,86% | 224W@4Ohms from a 763mV(rms) source

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Amp from the back

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Amp from the side

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Amp from the front

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mikey_audiogeek · 11th March 2017, 10:53 AM

Nice work!

RobFreak · 12th March 2017, 01:34 PM

Looks pretty neat!

r0b · 24th January 2018, 11:08 AM

Hi Bernd,

is this still in development? Always looking for good all-in-one packages for my next boombox build!

Cheers,

Robin

cacao ambiance · 24th January 2018, 03:12 PM

I like a lot what you have done. price is understandable idk for myself, would like it a lot... finishing boxing new TPA325* boards i’ve already got, hmm.... ooww....

Ive been following a chap that has been progressing making products in china and how he designed the products using cheap, ready available components. been quite interesting to read the details... anyway with potential interest in a batch, maybe he can put you in contact with good Chinese people that could help do a production run and get better component pricing, production optimisations, etc

i made a pledge to the crowdfund he ran/running
Earth-friendly EOMA68 Computing Devices | Crowd Supply
Rhombus-Tech
Mailing list best place to ask: The arm-netbook Archives
hes lkcl on the net/maillist/irc.
His info: Visionary - Technology - Poems - Stuff

9th March 2017, 11:08 PM	#72
mantabernd diyAudio Member Join Date: Aug 2012 Location: Germany near Munich	Attached the measurment of preamp. My setup Sig Generator ----------------------------------------> DSP ----------------------------------------> Preamp Out 0.46V/0.65V(rms/pkpk) ----------------------------- Gain: 0dB ------------------------------------ 3.28V/4.634V(rms/pkpk) This ends up in a gain of 17dB just for the preamp stage. I was a bit confused first because the gain must be 15.7dB but then I realized that I took a bit different resistor values as in schematics CH1 is measured at the output of DSP, CH2 at the output of Preamp. FFT Plot is for CH2. An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this. Last edited by mantabernd; 9th March 2017 at 11:10 PM.

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10th March 2017, 11:44 PM	#75
mantabernd diyAudio Member Join Date: Aug 2012 Location: Germany near Munich	Some more pics and measurments: FFT Ampout 1W@4Ohms An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this. THD+N 0,009% \| 10W@4Ohms from a 162mV(rms) source An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this. THD+N 0,86% \| 224W@4Ohms from a 763mV(rms) source An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this. Amp from the back An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this. Amp from the side An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this. Amp from the front An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

11th March 2017, 10:53 AM	#76
mikey_audiogeek diyAudio Member Join Date: Sep 2004 Location: Northland, New Zealand	Nice work!

12th March 2017, 01:34 PM	#77
RobFreak diyAudio Member Join Date: Dec 2009	Looks pretty neat!

24th January 2018, 11:08 AM	#78
r0b diyAudio Member Join Date: Sep 2009	Hi Bernd, is this still in development? Always looking for good all-in-one packages for my next boombox build! Cheers, Robin

24th January 2018, 03:12 PM	#79
cacao ambiance diyAudio Member Join Date: Oct 2015	I like a lot what you have done. price is understandable idk for myself, would like it a lot... finishing boxing new TPA325* boards i’ve already got, hmm.... ooww.... Ive been following a chap that has been progressing making products in china and how he designed the products using cheap, ready available components. been quite interesting to read the details... anyway with potential interest in a batch, maybe he can put you in contact with good Chinese people that could help do a production run and get better component pricing, production optimisations, etc i made a pledge to the crowdfund he ran/running Earth-friendly EOMA68 Computing Devices \| Crowd Supply Rhombus-Tech Mailing list best place to ask: The arm-netbook Archives hes lkcl on the net/maillist/irc. His info: Visionary - Technology - Poems - Stuff