Hi. Clueless n00b here! First look into DIY audiophilia.
I'm giving my son my Rega P1 and Cambridge Audio Topaz AM10 for uni. He's going to source some used bookshelf speakers off Ebay. I'm going to try a self-build to power my old Acoustic Energy floorstanders. That's a project for another day.
He wants to be able to stream via bluetooth to the amp too. I've bought a board for £8 off aliexpress, that uses the Qualcomm QCC5125 chipset and an ESS dac chip, with quite presentable results. At the moment, it's powered by a phone charger with output wires taped to a pair of phono inputs on the back.
There is a 3.5mm auxillary front-mounted input, which he plans to use for laptop input. The bluetooth board has an analogue audio input which, if bluetooth is not connected is passed through to the output. So the plan to make matters more elegant is to put the bluetooth board inside the chassis with the external antenna it shipped with mounted on the back of the amp. Wire the 3.5mm jack to the input of the bluetooth board then the output of said board back to where the 3.5mm output originally connected to the internal circuitry of the amp. Thus if bluetooth disconnected, the 3.5mm input just goes out to the new board and back again but if bluetooth connected, this input is overridden and the bluetooth audio plays.
The quandry is how to power the bluetooth board. I could drill a hole in the back of the chassis and run a usb cable in but it's a bit rubbish - you'd need to either leave it powered full-time or remember to power it up when you use the amp. Now, the amp has an LED array/display which lights up when you bring the amp out of standby. This appears to have a 5V supply. I am not an electronic engineer! Is there any danger in splicing wires from the +5V and GND wires from the LED display to the bluetooth board? That way, when the amp is brought out of standby, the bluetooth powers up and he'll have an amp that does everything he needs from one box.
Thoughts please!
I'm giving my son my Rega P1 and Cambridge Audio Topaz AM10 for uni. He's going to source some used bookshelf speakers off Ebay. I'm going to try a self-build to power my old Acoustic Energy floorstanders. That's a project for another day.
He wants to be able to stream via bluetooth to the amp too. I've bought a board for £8 off aliexpress, that uses the Qualcomm QCC5125 chipset and an ESS dac chip, with quite presentable results. At the moment, it's powered by a phone charger with output wires taped to a pair of phono inputs on the back.
There is a 3.5mm auxillary front-mounted input, which he plans to use for laptop input. The bluetooth board has an analogue audio input which, if bluetooth is not connected is passed through to the output. So the plan to make matters more elegant is to put the bluetooth board inside the chassis with the external antenna it shipped with mounted on the back of the amp. Wire the 3.5mm jack to the input of the bluetooth board then the output of said board back to where the 3.5mm output originally connected to the internal circuitry of the amp. Thus if bluetooth disconnected, the 3.5mm input just goes out to the new board and back again but if bluetooth connected, this input is overridden and the bluetooth audio plays.
The quandry is how to power the bluetooth board. I could drill a hole in the back of the chassis and run a usb cable in but it's a bit rubbish - you'd need to either leave it powered full-time or remember to power it up when you use the amp. Now, the amp has an LED array/display which lights up when you bring the amp out of standby. This appears to have a 5V supply. I am not an electronic engineer! Is there any danger in splicing wires from the +5V and GND wires from the LED display to the bluetooth board? That way, when the amp is brought out of standby, the bluetooth powers up and he'll have an amp that does everything he needs from one box.
Thoughts please!
@hoka - missed this, PM sent - https://www.aliexpress.com/item/1005005455956921.html is the board
@TBTL and @huggygood Thanks for your ideas. It looks like I've got things wrong anyway
I found the service manual for the AM10 (attached). I had just used a multimeter to test voltages and it appeared the 5V line from the CON5A on the input PCB only appeared to be live when the amp was taken out of standby but looking at the diagrams, I can't see why this would be so. I'm away from home at the minute so don't have access to the amp to recheck this.
The audio side of things appears straightforward enough. CON1B on the Amp PCB carries the input from the 3.5mm front mounted AUX/MP3 port. Connect the left 3 pins (audio L, R and GND) to the respective audio input on the bluetooth board, then the output from the board to the left hand 3 pins of CON1A on the input board, leaving the right hand 2 pins (DGND and DT1, whose purposes I am unsure of) running directly from CON1A to CON1B The bluetooth board has a relay switching from passthrough if bluetooth disconnected to override with BT audio when BT is connected.
Assuming that all looks OK, it just leaves the quandry of how to power the board internally from the amplifier. Ideally only powering the board when the amp is out of standby but not a dealbreaker I guess.
If anyone has any ideas where to draw the power from, I'm all ears! I am not sure how to connect up a DC-DC converter but we'll cross that bridge if theres a suitable supply I can use.
@TBTL and @huggygood Thanks for your ideas. It looks like I've got things wrong anyway
I found the service manual for the AM10 (attached). I had just used a multimeter to test voltages and it appeared the 5V line from the CON5A on the input PCB only appeared to be live when the amp was taken out of standby but looking at the diagrams, I can't see why this would be so. I'm away from home at the minute so don't have access to the amp to recheck this.
The audio side of things appears straightforward enough. CON1B on the Amp PCB carries the input from the 3.5mm front mounted AUX/MP3 port. Connect the left 3 pins (audio L, R and GND) to the respective audio input on the bluetooth board, then the output from the board to the left hand 3 pins of CON1A on the input board, leaving the right hand 2 pins (DGND and DT1, whose purposes I am unsure of) running directly from CON1A to CON1B The bluetooth board has a relay switching from passthrough if bluetooth disconnected to override with BT audio when BT is connected.
Assuming that all looks OK, it just leaves the quandry of how to power the board internally from the amplifier. Ideally only powering the board when the amp is out of standby but not a dealbreaker I guess.
If anyone has any ideas where to draw the power from, I'm all ears! I am not sure how to connect up a DC-DC converter but we'll cross that bridge if theres a suitable supply I can use.
Please double check the performance of that bluetooth board, before installing. Mine had horrible harmonic distortion, especially at higher volumes. One reviewer attributed it to the opamp. According to the photo, it likes to be powered from 7 to 18 Vdc.
I would take power from the cathode of D3 on page 10. Based on the linear +-8 V and +5 V regulators downstream, it is an aux power supply, somewhere between 11 and 25 V. Examples of isolated dc dc converters with a 9 V output voltage are:
Cui Inc. PQQ6W-Q24-S9-S or PQDE6W-Q24-S9-D
Mean Well SI06W8-09
XP Power ITZ0924S09
To power it only when the amp is out of stand by, there is a slim chance that the main power rails are shut down when the unit is on stand by. Check the voltage across C2 or the main bridge rectifier to be sure.
I would take power from the cathode of D3 on page 10. Based on the linear +-8 V and +5 V regulators downstream, it is an aux power supply, somewhere between 11 and 25 V. Examples of isolated dc dc converters with a 9 V output voltage are:
Cui Inc. PQQ6W-Q24-S9-S or PQDE6W-Q24-S9-D
Mean Well SI06W8-09
XP Power ITZ0924S09
To power it only when the amp is out of stand by, there is a slim chance that the main power rails are shut down when the unit is on stand by. Check the voltage across C2 or the main bridge rectifier to be sure.
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It works fine off 5v to the USB port and the sonic performance is adequate for what's required. The amp is really for the turntable but to avoid buying additional PC speakers and a Bluetooth speaker for streaming, he'd like to be able to use the same system for all of it. The Bluetooth performance doesn't need to be IFI Zen standard. My worry is causing noise interference on the turntable input.
The current kludge with a phone charger to power it and wires pushed into RCA sockets seems to work so if poss I'll make it tidier and more robust by installing internally. If it causes problems, out it comes
The current kludge with a phone charger to power it and wires pushed into RCA sockets seems to work so if poss I'll make it tidier and more robust by installing internally. If it causes problems, out it comes