SoloPiAmp

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SoloPiAmp

Postby gEnEsis_AiX » 16 Oct 2014, 09:11

Hi folks!

I am kinda new to this place, though i have used it to nourish my growing interest in the Pi and all its potential.

I bought my Pi B+ just a month ago, and I am truly amazed by the possibilities! Atm its running Elec and is a mediaplayer at the livingroom TV (supported by my gamerig/mediacenter in the cinemaroom). But my project reaches beyond my own knowledge and capabilities (i hope not). I want to make a PiAmp, one case Pi Streamer - with all integraded in one metalcase. But there ends my ideas :o Ive spendt countless hours searching for forumposts, blogs, build-instructables etc etc, but noone can keep the build like i want it, or in a way i can cope with.

What i have decided is this:
    - Raspberry Pi B+
    - HifiBerry I2S dac
    - 5v converter for power to the Pi
    - an on of switch for nuking down the Pi correctly
    - a 2x50w amplifierboard
    - a PSU working on 230/240v - giving 24-28v
    - possibility to connect a lcd-touch panels
    - everything shall have connections at the back (4x usb, hdmi, speaker-out, 230v in

My questions are as following:
    - what 2x50w amp is usefull? (have read about the TPA3116 and AudioBah-thingie Skrodahl is using)
    - will i need a preamp for this?
    - is there a way to connect a potmeter-or a volumswitch of any kind?
    - is there a way to power down the whole thing, also correctly powering down the Pi?

My biggest concern is that the build will require to much electrical knowledge and soldering work. I am going to be able to solder socets and pull wires, but i dont wanna unsolder anything from the pi or the amp board.

Is anyone doing something similar, and is able to tell me the answer to some of these questions? As this is my first DIY, i want it to be perfect:p
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Re: SoloPiAmp

Postby Aquarius » 16 Oct 2014, 14:57

Reply to some questions I hope not to be totally wrong:
- preamp needed ? Not strictly because for i²s dacs like the Hifiberry, you may use the volume control inside Rune. BUT. It's supposed to be something bad, according to audiophiles. You want volume control to take place in the analog world (i.e. after the DAC).
- To put a potmeter on the thing you need a Pre-amp different than volume control inside RuneAudio.
- With some code writing, and/or a script found on the net, you should be able to open/close a relay with the numerous GPIO on the Pi. so basically, you can use RunUI so switch off the Pi, then during the shutdown process, activate the relay to unpower the Amp board, pre amp, or whatever else you have in there, and then make sure that turning the Pi back ON with a switch will also close the relay to power up everything else. (an init script seems to be your best bet).
-- Aquarius
Hifi Gear: RuneAudio/Volumio on Raspberry Pi B + Hifibery Digi, Atoll ST200 (network streamer, DAC, pre-amp), Emotiva XPA-2, Bowers & Wilkins 683
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Re: SoloPiAmp

Postby matt » 16 Oct 2014, 19:30

I am intending on building the same thing and i too am concerned about my lack of electrical knowledge and have the same confidence re soldering.
I have just bought the "red" TPA 3116 board with built in volume control. I think this is the least liked of all the varients but I can swap it out later as they are so cheap, if so desired.
I am doing a very basic pi + power suppy in an aluminium enclosure as my first project.
There heaps of knowledge on here so just I am sure we will get there in the end. I
Please update your progress on here.
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Re: SoloPiAmp

Postby Fishstix » 16 Oct 2014, 20:12

Hey Guys,

I wouldn't be too scared of Soldering, it's pretty easy to pick up, and a great skill to have. Also the practice is *cheap.* :) When I first started, I just bought 1 dollar worth (read: a fistful) of cheap, through-hole resistors from radio shack, and a cheap prototyping board (with copper rings, so I could could practice heating wire and PCB traces at the same time.) I also picked up a small roll of de-soldering braid for a few bucks. Some people like solder suckers, but I find them overkill for the relatively small components I work with. For all of these along with a cheap soldering iron, you can spend as much time as you want soldering them to the board, then unsoldering, and then resoldering. Just takes a little bit of practice, some observation as to what you are doing, and a tiny bit of patience. To date: no cold shoulders (knock on wood) and no burnt components (knocking again.)

Lady Ada and Sparkfun both have good tutorials on basic soldering, which even being fairly familiar with, I learned new things from.

http://www.ladyada.net/media/common/soldering.pdf

https://www.sparkfun.com/tutorials/106

Lots of good info on these forums as to power supplies, pots, etc. Ask if you get stuck or worried; someone will be along to help you pretty quickly. You'll do just fine.

All the Best!
-Fishstix
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Re: SoloPiAmp

Postby matt » 17 Oct 2014, 02:54

Cheers for that Fishstix.
Your username makes me wonder, are you a Kanye fan? ;) https://www.youtube.com/watch?v=LRLyxjZtkzY
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Re: SoloPiAmp

Postby gEnEsis_AiX » 17 Oct 2014, 10:10

Can anyone do me the favour an give me a though about parts?


Is there anything ive forgotten?
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Re: SoloPiAmp

Postby skrodahl » 17 Oct 2014, 22:51

gEnEsis_AiX wrote:Can anyone do me the favour an give me a though about parts?


Is there anything ive forgotten?


The first amp board is good if you want to remove components and replace them with alternate/better ones. If you don't feel like changing anything, choose the second one. The green Audiobah amp also has no (actually very little) turn on/off thump.

The 5V step-down converter will work for your Raspberry Pi with DAC.

I would recommend that you use a laptop charger. Preferably if you find one at around 19 volts/4 amperes.

On/off switch. You could make a delayed switch which triggers a relay. It seems a bit complicated to me, because you don't want a delay when turning the power on. My suggestion is that the power button only controls the amplifier board, and that you leave the Raspberry Pi running all the time. It uses very little electricity.

A preamp is not needed. Using one will most likely give you better sound quality, but it may be negligible.

Finally, you'll need RCA connectors and speaker posts. Use insulated ones, and make sure they're not touching any metal in your case. Electrical cables are needed. Some thicker ones for the loudspeaker outputs. I highly recommend that you use shielded cables for all the audio interconnects (from RCAs to the amplifier inputs).

Both amp boards are using these connectors for audio input:
http://www.yuan-jing.com/shielded-audio ... 4-3p-awg28

If you plan to use a volume control (the easiest way is to use a 20k-50k stereo logarithmic potentiometer), connect this cable between the volume control and the amplifier board. Use a shielded cable from the RCA connectors to the volume control.

As long as you're visiting the Yuan-Jing site, it seems that they have the green amplifier board at a discount right now:
http://www.yuan-jing.com/tpa3116-class- ... d-anti-pop. You may want to support the eBay seller Audiobah for making this board though...

You could also consider buying a more complete solution. Like this one for instance:
http://www.yuan-jing.com/diy-kit-tpa311 ... -amplifier

Or this one:
http://www.ebay.com/sch/i.html?_odkw=SM ... A&_sacat=0

Or something in between:
http://www.ebay.com/sch/i.html?_odkw=tp ... p&_sacat=0

There's also this one:
http://www.yuan-jing.com/tpa3116-class- ... rd-50w-50w

As Downunder55 said in his post, there are projects that uses the TPA3118 (same as TPA3116, but with the thermal pad on the PCB side), that can be stacked on the Raspberry Pi. It might just as well be a reasonable way to go.
-skrodahl

Muffsy Phono Preamp PP-3 || Audiobah TPA3116 || ESP P88 || ProJect Debut Carbon Espirit DC || RuneAudio / RaspBerry Pi / HifiBerry DAC || Dynaco A25
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Re: SoloPiAmp

Postby gEnEsis_AiX » 18 Oct 2014, 19:59

One AWSOME runthrough Skrodahl (are you by any chance norwegian or something?)

I am surfing the Yuan Jing site, and they almost have everything! There is so much i want to put in there:p inputselector, speaker-protection, volume-control - I almost want it all.

but, for the easy way.

some more questions :p
- can i just split the power from the PSU to the 5v step down and amplifier
- can i put in a switch directly on the cables running to the amp, to power off the amp? nothing i need to think about?
- have i forgotten anything?

My ultimate goal is to have to SoloPiAmps - one to run a small touch screen for music on the hifi (also with an IPhone controll?) and to have one for the television in the living room. I want the smallest box i can get it all into, and its only gonna be -1- box - nothing more - fewest cables possible!
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Re: SoloPiAmp

Postby skrodahl » 19 Oct 2014, 10:32

gEnEsis_AiX wrote:One AWSOME runthrough Skrodahl (are you by any chance norwegian or something?)


You guessed it, I am Norwegian. :)

Good choice on the amp, and the power supply can be external. That way, you don't have to mess around with high voltages. The step down converter with USB connection will let you power the Raspberry Pi easily.

The shielded cable will work with the amplifier board, I suggest that you find more shielded audio cable by the meter that you can use for the rest of the build.

The speaker posts will work fine. Personally, I think something like this looks better though. I also got these rca connectors.

Over to your questions:

Yes, you can split the power. An easy way is to use these:

Sukkerbit.jpg
Sukkerbit.jpg (10.12 KiB) Viewed 4264 times


Once the power cables go to where you want them, you can just put a power switch on the positive cable coming from the power supply.

I can't see any glaring omissions. You probably won't need shielded power cables though. Just twist the cables, and the ground cable will create the shield. You might want to get a female power connector for the case, one that fits your
power supply cable.

I really like this case:
http://www.ebay.com/itm/full-aluminum-c ... 3a9081d6bf

With an external power supply, it will easily fit the amplifier and the Raspberry Pi + HifiBerry.
-skrodahl

Muffsy Phono Preamp PP-3 || Audiobah TPA3116 || ESP P88 || ProJect Debut Carbon Espirit DC || RuneAudio / RaspBerry Pi / HifiBerry DAC || Dynaco A25
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Re: SoloPiAmp

Postby gEnEsis_AiX » 19 Oct 2014, 14:29

Næmmen, hei fra det blide vestland :) (for those not familiar with norwegian - Hello from the happy west-part of norway)

I got everything lined up, just need a female socet for power inn, and shielded power cable / speaker cable - but i cant find any usefull on ebay - what do i search for (only found for 1000-2000 NOK)

When it comes to case, i need a case that is broad enough to be able to use the HDMI cable (PI is 56mm) and then i need an angled plug.
So it has to be:

( Pi lenghts (86mm) + amplifier (64mm) ) x ( PI width ( 56mm) + hdmi 270 degree angle ( 50mm ???) ) = 150 x 110 ish. should add some on both the lenght and width - so 180 x 120 ( then i can also have the tpa3116 board (the blue one)

Do i forget anything?
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