TPA3116 / RuneAudio Project

StivVid

That's a great looking build! It's coming together very nicely. I love the fact that you've built your own phono preamp. I took the lazy route and bought a Technolink TC-754 that I plan to incorporate in my build. That will give me a phono preamp, switching for up to 3 more inputs, and volume control. I'll hook that up to my TPA-3116 board and Raspberry Pi with IQaudio Pi-DAC. The form factor is quite a bit different from your build, but I won't say any more until I'm further on in the build. Want to keep it a surprise. I'll post pictures soon.

I had no idea that I could power my Pi using your technique. I may have to try that. It takes USB out of the loop and may solve some noise issues. I'll try one more possible solution first, then we'll see if your way works.

Keep posting updates about your build. You've taken some great pictures that have given me ideas for my own build. Really appreciate the information.

Downunder55

skrodahl wroteSo, here it is. My little preamp, or closer to a buffer, built on the jfet transistor MPF102 in class A.

I don't have the time to do a listening test yet. I need to rearrange components on the board to place inputs/outputs correctly, and I need to install the RIAA stage so I can see where to fit the preamp in my enclosure.

Skrodahl have you had a chance to have a listen yet ? .... does it POP ?

When I had the Pre-Amp battery powered I had a reasonably loud POP through the speakers when I turned off the Pre-Amp, I have since made the filtered power supply and powered it off the same laptop power supply as the amp, I now get an even louder POP (unnervingly forceful) when I switch them both off, without the Pre-Amp there is only the faintest pop.

Downunder55

skrodahl wroteBTW, isn't it übercool and satisfying to know that you have built this yourself? 8-)

Ummmmm......Yes, .....may have built it but ............ it's all black magic and mystery as to why it all works !!!! :lol: :oops:

This is how I integrated the power filter in to the original build, it seems correct but the big POP really worries me and it is defn not friendly to the speakers !

Downunder55

StivVid wrote
Hi, guys!

It seems we've all had a very similar idea. In fact, I've bought the same USB power supply board as Downunder55 and am having the same ground loop issue. At first, I was using a Sure (like a Mean Well) power supply and thought maybe the power supply was the culprit. I'm now using a laptop power supply and the noise is still there. It's a hum with a crackling that coincides with Raspberry Pi activity--anytime the LEDs are flashing on the Pi, the crackling is very audible.

I've noticed that there are pin outs on the USB board that supply 5V while bypassing the USB connector. I'm wondering/hoping that this 5V output might be isolated better? Gonna give it a try. Let you know what happens.

I've been doing a little research on this problem, and am finding that USB is very noisy unless its power supply is isolated from the main power supply's ground. At least that's how I understand it. There are isolated power supplies for USB that solve the issue, but they're expensive and don't supply any more juice than about 500mA. Not enough, I'm afraid.

The only solution I've found so far is to run the Pi off a separate power supply, which isn't the elegant solution I was looking for.

Hi StivVid,

Have you had any luck in resolving the grounding issue ?

Other than connecting the ground plate of the Amp to the ground on the HiFiBerry or having a separate PS I am at a loss at the moment. Even connecting that wire doesn't eliminate it totally.

I really did want to use a single PS for my "self-contained Player".

skrodahl

Omg, omg, omg, omg, omg, OMG!!!!
The phono stage is now working, and boy is it working!

I had a ground loop and a big hum, and I don't know if it applies to the problems you've been having, but I connected the ground on all RCA input connectors together. That solved it, and this thing is dead quiet.

The build of my RIAA stage, in particular, has taken a looooooong time. But it's definitely worth it. I am close to crying out names of random deities, praising the places where they reside. It is just fabulous!

If there's any doubt, I like this. A lot.

skrodahl

Downunder55 wrote Ummmmm......Yes, .....may have built it but ............ it's all black magic and mystery as to why it all works !!!! :lol: :oops:

It's what transistors do, they amplify. In this case we are also providing better impedance match. In other words, a better fit between the music player and the amplifier.

I found a great explanation on the web on how transistors work:
http://www.build-electronic-circuits.com/how-transistors-work/

Downunder55 wrote This is how I integrated the power filter in to the original build, it seems correct but the big POP really worries me and it is defn not friendly to the speakers !

The power filter, as you have drawn it, is correct.

I still haven't been able to test the preamp, I've been to busy being ecstatic about my phono stage (which in all honesty might be a bit off topic, but it is a part of my amplifier build).

The blue/black TPA3116 board does pop, and I hope this preamp won't make it worse. If it does, expect another simple preamp based on an operational amplifier.

The absolutely simplest way of eliminating the POP would be to turn down the volume. That might not always be practical, and you may forget to do so from time to time. Another solution is to install a delay circuit to get rid of the pop.

--------
Please note: I have not tested this. It won't destroy anything, but it may or may not work as a way of eliminating pop.
--------

Here's one example of such a circuit. It will delay both power on and power off. You should place it between the PSU filter and the preamp. The upper connection of the lamp in the picture will go to your +Ve, the lower connection of the lamp will go to your -Ve.

Cheap alternatives for Q2 (as long as you only use it for powering the preamp, and not the amp) are 2N7000 and BS170. They will both provide a couple of hundred milliamperes. (Looking back on the transistor explanation, these transistors are used as power on/off switches. The rest of the circuit creates delay.)

Peter

I still haven't been able to test the preamp, I've been to busy being ecstatic about my phono stage (which in all honesty might be a bit off topic, but it is a part of my amplifier build).

Congrats on the successful implementation of your RIAA preamp! I'm glad you are pleased. :lol:

I have started investigating the opamp preamplifier, while waiting for my Vero board to arrive (ebay) so I can complete the jfet preamplifier. This one http://sound.westhost.com/project88.htm from Rod Elliott is what I am looking at at the moment.

Also just ordered a breadboard, the way things are going, circuits will need to be tried before final construction.

skrodahl

Peter wrote
I still haven't been able to test the preamp, I've been to busy being ecstatic about my phono stage (which in all honesty might be a bit off topic, but it is a part of my amplifier build).
Congrats on the successful implementation of your RIAA preamp! I'm glad you are pleased. :lol:

I have started investigating the opamp preamplifier, while waiting for my Vero board to arrive (ebay) so I can complete the jfet preamplifier. This one http://sound.westhost.com/project88.htm from Rod Elliott is what I am looking at at the moment.

Also just ordered a breadboard, the way things are going, circuits will need to be tried before final construction.

Thanks a lot,
It's funny you should mention ESP P88, because I just got one:

It shouldn't take many days before I have the opportunity to test it. 🙂

Peter

It's funny you should mention ESP P88, because I just got one:

Did you just buy the board and build it, or did you purchase made up?
:?:

skrodahl

And wouldn't you know it. The Audiobah amplifier board also just arrived. 🙂

It's tiny!

Edit: Audiobah installed.

What disturbed me about the previous (blue/black) board was some sibilance. That's completely gone with this new amp. Apart from that, I would be hard pressed to confidently describe any difference. I imagine that it sounds a bit more open, more like my old TriPath TA2020.

Edit 2: The Audiobah board has absolutely no turn-on pop, and just a faint turn off-pop at high volume.

skrodahl

Peter wrote
It's funny you should mention ESP P88, because I just got one:
Did you just buy the board and build it, or did you purchase made up?
:?:

A long story.
The short of it is that I bought the board, built it, misplaced it and got it back today.

StivVid

Nope. Still haven't worked out the grounding issue. Haven't really had a chance to play with it much.

I'll be sure to post the solution if I find one. Would really like to use a single power supply for the whole rig.

Downunder55

skrodahl wroteI found a great explanation on the web on how transistors work:
http://www.build-electronic-circuits.com/how-transistors-work/

This was a great simple explanation thankyou !

skrodahl wroteI still haven't been able to test the preamp, I've been to busy being ecstatic about my phono stage (which in all honesty might be a bit off topic, but it is a part of my amplifier build).

CONGRATULATIONS ...... great when a plan comes together !

skrodahl wroteThe absolutely simplest way of eliminating the POP would be to turn down the volume. That might not always be practical, and you may forget to do so from time to time. Another solution is to install a delay circuit to get rid of the pop.

I get the POP with or without any volume, as you said the turn off pop from the Audiobah is very very low, but with the pre-amp in place is near speaker destroying !.

Thanks for the delay switch idea/link but rather than look at another circuit in the mix just yet, I am going to build another JFET PreAmp with my new found better soldering skills and see if it is a construction error that is causing the POP ..... having said that, in removing some of the components from the old board (seemed quicker than going down to the store) I ended up juggling the soldering iron and rather than let it fall in my lap I grabbed the hot body with my hand Ouch !!!! ...... and now have two lovely burn blisters that will slow me down for a couple of days I think !!!!

If this doesn't eliminate the POP maybe a little ESP P88 project maybe the go !

skrodahl

Hope you're recovering from the soldering iron accident. If you keep on soldering, you will realize that it happens quite too often.

I have another omg, omg, omg, omg, OMG!!!! moment going here. The P88 preamp is installed, and it works beautifully. I was a little worried that my small 83 mA dual rail PSU would have trouble driving four OPA2134s. They require 40 mA quiescent current, so it was going to be on the limit. But I'm happy to report that it works great.

I had to mount the preamp on top of the phono stage. It's getting cramped, especially with the cabling making everything hard to move around. I would prefer some of the cables to be even shorter, but I don't think that's physically possible. And, it was inevitable of course, I got a small soldering iron burn on my thumb...

I thought the Audiobah TPA2116 amp delivered a very detailed and clear sound. Playing vinyl was even better than the sound from RuneAudio, which made me suspect that a preamp would be nice.

My suspicions were absolutely correct. The level of details, the highs, the lows, the mids, the "blackness" of the silence, the positioning of every possible sound and instruments. It is just unbelievable. There might come a day when I find something better, but I seriously doubt that right now.

Downunder55

skrodahl wroteHope you're recovering from the soldering iron accident..... If you keep on soldering, you will realize that it happens quite too often...

Yes thanks ..... "it's just a flesh wound"

Well I built the second JFET Pre-Amp and while the sound is just great again I still get the POP, but building this has been a great exercise and have really enjoyed it, Skrodahl you are so correct.

Funnily this cheap little preamp has created quite an associated expense trail of it own...... soldering iron, soldering iron holder, brass tip cleaner, pcb holder with magnifying glass, multimeter, Dremel type tool, small suction vice ....... is there no end to the great gadgets ..... 😃 😃 😃

skrodahl wroteI have another omg, omg, omg, omg, OMG!!!! moment going here. The P88 preamp is installed, and it works beautifully

Sensational, congratulations....... you do sound reasonably happy about this !!!

skrodahl wroteI thought the Audiobah TPA2116 amp delivered a very detailed and clear sound. Playing vinyl was even better than the sound from RuneAudio, which made me suspect that a preamp would be nice.

My suspicions were absolutely correct. The level of details, the highs, the lows, the mids, the "blackness" of the silence, the positioning of every possible sound and instruments. It is just unbelievable. There might come a day when I find something better, but I seriously doubt that right now.

Ok .... I'm convinced a Rob Elliot Project 88 is the next bit of fun, thanks Skrodahl for all the ideas, hope you don't mind me copying your path :oops: but, it's great to learn from someone who knows about this stuff !

I really wasn't looking for a balance control, could this be excluded ? .... but suppose I could use a small pot so as not to be too intrusive.

skrodahl

Downunder55 wroteFunnily this cheap little preamp has created quite an associated expense trail of it own...... soldering iron, soldering iron holder, brass tip cleaner, pcb holder with magnifying glass, multimeter, Dremel type tool, small suction vice ....... is there no end to the great gadgets ..... 😃 😃 😃

Hehe 🙂 If you're anything like me, there's nothing quite like a good excuse to get more tools.

Downunder55 wroteSensational, congratulations....... you do sound reasonably happy about this !!!

Yes... Reasonable happy was exactly the emotion I was trying to convey. 😃

Downunder55 wroteOk .... I'm convinced a Rob Elliot Project 88 is the next bit of fun, thanks Skrodahl for all the ideas, hope you don't mind me copying your path :oops: but, it's great to learn from someone who knows about this stuff !

I really wasn't looking for a balance control, could this be excluded ? .... but suppose I could use a small pot so as not to be too intrusive.

The balance control can be omitted, it's all there in the instructions if you buy the PCB. I kept it because it can come in handy for some vinyl records where the balance can be off. It's also the most forgiving balance control I've ever encountered, the center point is really wide.

skrodahl

Now that the P88 preamp is installed, I played around with the sound signatures in the settings.

Just when I thought things couldn't possibly get better, I found that switching to Orion V2 improved the sound even further.

Hotel California/Hell Freezes Over has never sounded better.

ACX

skrodahl wroteNow that the P88 preamp is installed, I played around with the sound signatures in the settings.

Just when I thought things couldn't possibly get better, I found that switching to Orion V2 improved the sound even further.

Hotel California/Hell Freezes Over has never sounded better.

If you can finally hear the differences between the profiles, it means that your setup is revealing enough. In other words... congratulations! You built a good system 🙂 Moreover, the Orion V2 profile usually rewards "tight" setups improving PRaT and detail.

Hotel California/Hell Freezes Over is also one of my favourite test tracks (I wrote it in the dedicated thread).

skrodahl

ACX wrote If you can finally hear the differences between the profiles, it means that your setup is revealing enough. In other words... congratulations! You built a good system 🙂 Moreover, the Orion V2 profile usually rewards "tight" setups improving PRaT and detail.

Hotel California/Hell Freezes Over is also one of my favourite test tracks (I wrote it in the dedicated thread).

The differences between the profiles have been audible all along, and I love that feature. Up until I added the preamp, I switched between the default RuneAudio profile and yours. I even dabbled with a few of my own profiles, but none of them were as good as either of the built-in ones. I guess you have been spending quite some time experimenting with the different parameters.

As for the amp, it is really fantastic. It's been about two and a half months since I started the build, and I had a clear picture of what I wanted. Four inputs, built-in PSU, an amplifier, a RIAA stage, volume and balance.

What took the longest time was figuring out how to power the phono stage. The preamp was an afterthought, but I'm happy that it fit in the enclosure and that the dual rail PSU had just enough juice to power both the RIAA stage and the preamp. I wanted the Raspberry Pi to fit in the enclosure when I started out, but I rather like that it's modular.

Now that it's all come together I couldn't be happier with the result. Off topic, I know, but I am utterly amazed at how good vinyl actually can sound. :shock:

I actually took the Hotel California tip from you, thanks for suggesting it. 🙂

skrodahl

I did some matching of the preamp, P88, to the Audiobah board. It will work for most of the other TPA3116 boards as they all seem to have a 26 dB gain.

With the standard P88 board at the lowest gain setting, I had a usable volume control range up to about 10 o'clock before the volume was way too loud.

The second gain stage of the P88 needs to have some gain to avoid oscillation, the lowest setting is at 4.44 dB. So I looked at the first gain stage. It can be set to 0, or unity gain, but I decided to keep a little gain anyway. Changing R3 (left and right) from 10k ohm to 750 ohm gives 0.63 dB gain. A total of just about 5.1 dB for the whole preamp.

The volume/balance setup has a loss of 3 dB, so in total the preamp has just a smidge above 2 dB gain. The volume control is usable over a much wider range again. 🙂

A 2V input signal was amplified to ~4.7V in the original preamp setup. It is 2.5 volts with the new setting. Of course, this makes it less like a preamp and more of a buffer. Not surprisingly, it still sounds just as great.

Edit: With lowered input signal, and the amp operating at more reasonable levels, the sound is getting much richer/warmer/fuller. So much in fact that I had to go back to the RuneAudio sound signature. It does offer a very natural and transparent sound.

« Previous Page Next Page »