Thank you! The Gui is not finished, yet but it's a first impression.
Next step is to implement the rotary encoder and buttons. Actually I just want to have a rotary encoder as the only navigation and control input, without any buttons. Let's see if it's possible.
Yes... I already did some calculations (what ended up in a huge, huge excel sheet) and I came up to a price of 500 Euros including german taxes (19%).
This price includes
- the amp with heatsink and high quality inductors, caps, post filter feedback and OPA1632 input stage with symmetrical power supply
- the dsp board with bluetooth (incl. aptX)
- the rotary input
- cinch adapter board
- Oled Display (256x64px)
I know that this price is high and I wished to lower it but it's almost not possible with just a couple of builts. Many parts are really expensive when you just buy a small amount of them. Plus the fact that this amps are hand build in my lab.
On the other hand you will get a full amp with DSP, Display and all control inputs. You just need to connect a power supply and have fun. You don't even need a additional supply for display etc...
Regards
Bernhard
Next step is to implement the rotary encoder and buttons. Actually I just want to have a rotary encoder as the only navigation and control input, without any buttons. Let's see if it's possible.
Will it be for sale?
Yes... I already did some calculations (what ended up in a huge, huge excel sheet) and I came up to a price of 500 Euros including german taxes (19%).
This price includes
- the amp with heatsink and high quality inductors, caps, post filter feedback and OPA1632 input stage with symmetrical power supply
- the dsp board with bluetooth (incl. aptX)
- the rotary input
- cinch adapter board
- Oled Display (256x64px)
I know that this price is high and I wished to lower it but it's almost not possible with just a couple of builts. Many parts are really expensive when you just buy a small amount of them. Plus the fact that this amps are hand build in my lab.
On the other hand you will get a full amp with DSP, Display and all control inputs. You just need to connect a power supply and have fun. You don't even need a additional supply for display etc...
Regards
Bernhard
Well yes, I agree with you.
The most expensive parts are:
- inductors 32,40 EUR
- oled display: 36,19 EUR
- Bluetooth module: 35,80 EUR
This already are 104,39 EUR.
So you need to see that this is far more than just a bare amp. You don't even need a preamp, you can even connect a smartphone directly without any preamplification.
The gain settings of most other amps are not high enough or will end up in a loud background noise at the speaker because the input stages are not designed well enough.
Furthermore a complete volume control etc. is already implemented.
The most expensive parts are:
- inductors 32,40 EUR
- oled display: 36,19 EUR
- Bluetooth module: 35,80 EUR
This already are 104,39 EUR.
So you need to see that this is far more than just a bare amp. You don't even need a preamp, you can even connect a smartphone directly without any preamplification.
The gain settings of most other amps are not high enough or will end up in a loud background noise at the speaker because the input stages are not designed well enough.
Furthermore a complete volume control etc. is already implemented.
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We both know that prices are much much lower when bought in quantities for the industry. It can be frustrating to see a ready made encased product with those same parts sold for less.
Put my money on ready made FDA amps. Putting much time in an expensive design when new/better chips come out every few months is not very rewarding.
Put my money on ready made FDA amps. Putting much time in an expensive design when new/better chips come out every few months is not very rewarding.
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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..
Well... on the other hand ~500 EUR incl. tax is not compareable to a chinese build but indeed a fair price if you have a eye on the fact that you get a full DSP (like the well known MiniDSP) and a complete user interface with a nice oled display.
If you sum up a regular build you will end up at the same price but with my design you have the advantage that all components are on one board. Including the fact that my components and quality is better than most of chinese designs.
If you sum up a regular build you will end up at the same price but with my design you have the advantage that all components are on one board. Including the fact that my components and quality is better than most of chinese designs.
Yes because I had a eye on every part to choose the best fit and not the cheapest one.
Plus my low noise fully differentially preamp buffer with symmetrical power supply is way better than the preamps of most other builds.
My preamp got a gain of 20, so you can connect a low level source like a smartphone directly to my amp while still having a low noise.
This took some time to design and it's not possible to reach with a poor choise of parts.
Plus my low noise fully differentially preamp buffer with symmetrical power supply is way better than the preamps of most other builds.
My preamp got a gain of 20, so you can connect a low level source like a smartphone directly to my amp while still having a low noise.
This took some time to design and it's not possible to reach with a poor choise of parts.
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.
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.
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 was not working when we last tested it.
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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.
BT module is from bluegiga:
WT32I-A-AI6-APTX
Is this a question or a fact? What exactly do you mean this this?
Some more pics and measurments:
FFT Ampout 1W@4Ohms
THD+N 0,009% | 10W@4Ohms from a 162mV(rms) source
THD+N 0,86% | 224W@4Ohms from a 763mV(rms) source
Amp from the back
Amp from the side
Amp from the front
FFT Ampout 1W@4Ohms
An externally hosted image should be here but it was not working when we last tested it.
THD+N 0,009% | 10W@4Ohms from a 162mV(rms) source
An externally hosted image should be here but it was not working when we last tested it.
THD+N 0,86% | 224W@4Ohms from a 763mV(rms) source
An externally hosted image should be here but it was not working when we last tested it.
Amp from the back
An externally hosted image should be here but it was not working when we last tested it.
Amp from the side
An externally hosted image should be here but it was not working when we last tested it.
Amp from the front
An externally hosted image should be here but it was not working when we last tested it.
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
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
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