TPA3116 / RuneAudio Project

[Peter]

Some pictures of TBA II, with the Sure board.

Antique speaker box purchased for NZ$1

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Restored box, with original bakelite knob used for volume control. Original makers mark retained (dark patch on left).

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Back, with Sure board mounted on perspex with rubber isolators. Volume control attached to cross strut, and power switch with led on plate with RCA inputs. The acrylic sheet behind the grill (sanded to reflect light) has embedded leds which glow yellow through the slats in the dark.

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[Peter]

Last images....

Skew view showing wiring. Once again, the resistors to turn the linear pot to a log pot are encased in blue heatshrink.

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Speaker cut off / mute switch, which will be installed when the binding posts (on order) are fitted. This plate will be fitted to the left of the volume control, opposite the power switch and input plate.

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The speaker switch is to prevent switch on and off pop. I figure this is the same as an A/B speaker switch and it works for me.

A Raspberry Pi B+ and Audiophonics I2S DAC will be added to the top of the case, upside down at a later stage.

Power supply is an ATX power supply, running on 12v currently. Plenty of power, and the option to run on 24v if I so desire. This power supply will enable me to power the Pi and DAC from the same source, just using the 5v rail.

This build is not nearly as pretty or professional as yours skrodahl, I wish I had your ability! Quality of the sound, however is just great. No hum, feedback distortion or any issues - must be the oversupply of ferrites!

The board has just arrived for the jfet preamp, so let the building begin!

[skrodahl]

That's a seriously cool retro look you've got going there. I was looking for a case like this for the longest time, but couldn't find anything close to what you have there. That's why I have the more modern looking enclosures for my TPA and my Pi.

Keep the pictures and progress reports coming.

[skrodahl]

My build is finally completed, I have held off connecting the final two inputs because I had to get around the space constraints.

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All the cabling is now neatly kept in place with zip-ties, and everything is tested. The enclosure will probably not be opened again anytime soon, unless I get some other idea.

I have now reached what I set out to do:

* A TPA3116 amp
* A RIAA stage
* 4 inputs, with input selector
* Volume
* Balance
* Internal power supply, with fuse

I even ended up with a preamp inside the case. All in all, a nice little integrated amplifier with great sound.

If it hadn't been for the initial stunning results with RuneAudio, I most likely wouldn't have built this at all.

This thread has seen a few other builds and plans too. Keep the updates coming, and perhaps we will inspire others as well.

[Peter]

My build is finally completed,

Well done on an excellent professional build. One question....what are you doing with the bue/ black amp? Surely you will build something else? Maybe with an integrated Pi and DAC?

On a selfish note, could you please post a schematic of your jfet amp, it will be much appreciated. I am designing my own, but am learning stripboard from Downunder55 and (hopefully) you. I am using Fritzing for a schematic tool which seems OK.

[skrodahl]

Thanks Peter,

I have another 0905 case (like the one for my Raspberry Pi), that I thought could be a good enclosure for the YJ board. I usually assign old gear far too less sentimental value, so I end up giving away stuff that I perhaps should have kept. The YJ board will probably be given away, introducing others to both Class-D and TPA3116 in the process.

I even have a uDAC that could fit in the chassis, thanks for the idea!

I'll bring out my jfet pre, and do a drawing of the circuit. It was just adding components as you go, Downunder55's layout is far superior. (Although, you don't have to cut that many tracks with mine).

While on the subject: Using a modern source that gives a 2V signal together with a non-modified TPA3116 @26dB gain, requires very little gain from the preamp. I stumbled over this jfet buffer:

http://boozhoundlabs.com/collections/al ... kit-2sk170

...and a jfet RIAA preamp:
http://boozhoundlabs.com/collections/al ... kit-2sk170

The circuits are in the PDFs at the bottom of the page, and you can even buy all of them in kit form. You don't have to feel compelled to use the extreme capacitor variants, although they are quite cool.

[Fin]

Mind reader! I was thinking of asking about a simple buffer rather than preamp.

I'm very gradually collecting the parts for my own build, hoping to use the hardware volume control of the IQaudio PiDAC and the audiobah board that I just got my hands on the other day.

I've mainly lurked the threads without much comment, but I have to say I've appreciated all the progress and info posted so far.

[skrodahl]

Mind reader! I was thinking of asking about a simple buffer rather than preamp.

Cool, and welcome to the forums. I'm looking forward to seeing your results.

I just did an inventory, and I found that I have everything needed to turn the spare YJ/BlackBlue into a working amp:

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To do, or not to do... It wouldn't be hard to power an opamp buffer with the main amplifier power supply (I plan to use a 14V psu). The input impedance is a bit high on this circuit though, R1/R2 should probably be somewhere between 50k-200k ohm:

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I'll probably skip the balance control this time though.

[Peter]

I just did an inventory, and I found that I have everything needed to turn the spare YJ/BlackBlue into a working amp:

Heh, Heh, thought you might. I'm now thinking of a nice aluminium case for one of my (or a new) amp, with more inputs and a selector.

[skrodahl]

I really liked your retro look though Peter. I am still looking for an unconventional case for an amp.

As a main system, more inputs are really useful. I'll see what I do if I find a nice enclosure.