Simple amplifier circuit to boost a weak line-level signal

This is a cool thread - reminds of me of the shruthi days, when there was more talk about DIY and figuring things out for yourself. Not that I have an issues with the forum nowadays, I just enjoy DIY problem-solving!

…except that this is infinitely simpler, of course. :wink:

Would anyone like to have a nice PCB for this?

Found a pretty decent ’90s style semi-transparent case!

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I would buy a PCB for this project; I have 3 Boutique instruments and have noticed the same thing about low levels, which is not so much of a problem for recording (I just run them through a good clean front end), but if i want to bring the Boutique into Euroland, things get wonky. You’ve built a beautiful little solution there…

:joy::persevere::joy: Just like the first generation of iMacs?

Exactly! I also plan to move it into an all-aluminum dark grey pro enclosure two decades from now… :wink:

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Thanks, but credit really should go to @pichenettes; I pretty much just did what he told me to. :slight_smile:

Let’s find out if there are others. I’ll see if I can get my hands dirty with PCB design and production if there’s enough interest.

Tried to see if there’s any difference in noise between the small linear power supply and the Traco Power TRN1-1222 today. Here’s a normalized recording with the linear supply first, followed by the Traco Power.

noise.wav.zip (1.5 MB)

I can’t say I hear any real difference. Please note that this is with a TR-09 plugged in and the levels on the mixer and the audio interface all turned up.

@t2k do you have some PCBs for this available? I’m interested in putting one together to boost multiple signals to Euro level, and it seems like this might work as-is or one could switch resistor values to adjust gain, right?

thanks in advance!

I never made a PCB because there was very little interest and because it can be done pretty nicely on a breadboard.

Hi tK2

I would really like to have a crack at doing one of these, to get line level into Eurorack.

Do you have some kind of simple sketch/schematic/photo that you could post. It looks very doable with a low part count, but some of the circuitry is a little obscured.

It’s a shame that you did not get enough responses to warrant the making of a small run of pcbs.

Cheers

See above. The photo in my december 17th comment is probably the one that gives you the best idea of how to wire things up.

My recommendation would be to build it on breadboard first to make sure you’ve got it working like you want to before you start soldering anything.

That could have been nice, but those Adafruit perma-proto boards are actually pretty great for something as simple as this. For eurorack, you might want to take a look at https://www.davidhaillant.com/eurorack-stripboard/

Hey tK2

Thanks for the info

I think I will get a Eurorack protoboard when I have the first bit working

Cheers

Simon

The Boutique Booster™ is now for sale! Asking €40 including shipping within Europe and complete with power supply and 6 TRS straight to angled minijack cables.

Price drop!

Hi t2k

I just found this from way back. I was following the same thread.(yesterday)…then I noticed the conversation, then I noticed (I missed it when I looked yesterday) that it was me…doh!!
Is this still for sale. Line level to eurorack level?
Sorry about the delay. Can’t understand how I missed it.
Cheers

Simon :grinning:

Still available! @rectec, you might want to check your DMs. :slight_smile:

On your layout, I can‘t see where the components are supposed to be connected. Especially the resistors.
And the traces under the diodes have to be disconnected.

Hi cj55, I’ve cleaned up the layout, built it and can confirm it’s working. Thanks for pointing out the missing component leads and the missing track cuts for the diodes. :slight_smile: