Adam_C

Getting started with audio circuits?
« on: November 20, 2020, 07:33:16 PM »
Hello all,

Apologies if this is in the wrong place but I'm seeking some advice!
I've studied electronics for a couple of years during my audio degree so I have a basic idea of how filters, op-amps, and some other basic circuitry works with the theory behind it, but I haven't had much of an opportunity to apply this to practical ciruits.

I was wondering if anyone could suggest a good way to start fiddling and mucking about with circuits in a safe way? Any good books too read to help out? (I've found Self's Small Signal Audio Design to be very useful). If making eq's and whatnot on breadboards, what is the best way to send audio and return it? Are there any 'kits' that would help with starting out?

I'm very interested in 500 series modules and was wondering if there was any easy workflow in adapting regular circuits to the 500 series format? Or perhaps some 500 series oriented articles/books?

Apologies for all the questions, would be great to hear some thoughts!

Thanks,

Adam


Whoops

Re: Getting started with audio circuits?
« Reply #1 on: November 20, 2020, 09:19:22 PM »
I've found Self's Small Signal Audio Design to be very useful

A lot of people seem to recommend that book, so it must be good.
Also do a search on "Books" here on the forum you will find other good recommendations.

If making eq's and whatnot on breadboards, what is the best way to send audio and return it?

Dont know if I understood correctly what you're asking...
Send audio in, you can use your phone, an mp3 player, a tablet a computer. A signal generator
Audio returns to an amplifier, a T-Amp or any small powered computer speakers

I'm very interested in 500 series modules and was wondering if there was any easy workflow in adapting regular circuits to the 500 series format? Or perhaps some 500 series oriented articles/books?

No books that I know of. But besides getting the pinout and physical dimensions there's not much to know,it's nothing hard.
You have balanced audio in  and out, you have + and - 16V rails. a 0V reference and maybe a chassis/shield connection.
If you want to use a circuit that doesnt work on +- 16V you need a DC converter.
Thats it, what would you like to know more?

Re: Getting started with audio circuits?
« Reply #2 on: November 20, 2020, 09:52:01 PM »
Small Signal Audio Design is a great book but I would advice against reading it before you have a very solid background of the fundamentals. Another great one is "The Art of Electronics" by Horowitz/Hill, this book will teach you about electronics in general but it can be overwhelming at times, "Electronic Principles" by Malvino is an easy introductory book about analog electronics like the diode, transistors, transistor configurations, etc.. operational amplifiers; buy a used one, if you want something more advanced, "Microelectronic Circuits" by Sedra/Smith is a personal favorite. For operational amplifiers "Design with Operational Amplifiers and Linear Integrated Circuits" by Sergio Franco and "Operational Amplifiers" by Roberge (which is considerably more advanced) are probably some of the best books on the subject.

For vacuum tubes and much more the bible is "Radio Designer's Handbook" 4th edition, by Smith, this book is a classic but it does require you to know the fundamentals very well so you might want to start with another book called "Valve Amplifiers" by Morgan Jones.

Read application notes, for example Texas Instruments, Analog Devices, ST, etc.. have many great tutorials and application notes. Jensen transformers, Lundhal and Sowter have a lot of literature on transformers. THAT has a lot of material on preamps, line recievers/drivers, VCAs and dynamic processors.

There is a book META somewhere around the forum.

Regarding 500 series projects, instead of trying to adapt circuits to work on the 500 series, I would rather start with some already made projects for the 500 series. This forum has a ton of projects, some users sell PCBs, parts, racks, etc... the search function is your friend.

Welcome to the forum!

« Last Edit: November 21, 2020, 03:07:22 AM by Dualflip »

Re: Getting started with audio circuits?
« Reply #3 on: November 25, 2020, 05:39:21 AM »
I'm very interested in 500 series modules and was wondering if there was any easy workflow in adapting regular circuits to the 500 series format?
500 modules work in exactly the same way as your breadboard circuits, they're just squeezed into a 500-shaped box. You still have in, out, and bipolar power rails. That's all you need to get started.

Quote
what is the best way to send audio and return it?
Not sure what you mean by that, but if you want to make your life easy you can just drop in an INA IC to unbalance your signal, then feed it into your breadboard circuit. Then you can use a DRV to balance it up again on the way out. Yes there are other ways, but if you're still learning then you might prefer these one-chip solutions to begin with, so you can focus on the interesting stuff inbetween.

Newmarket

Re: Getting started with audio circuits?
« Reply #4 on: November 26, 2020, 08:30:24 AM »
Small Signal Audio Design is a great book but I would advice against reading it before you have a very solid background of the fundamentals. Another great one is "The Art of Electronics" by Horowitz/Hill,

just chipping in to give a big thumbs up to those two books.
Plus Jensen app notes and RANE stuff too.

Re: Getting started with audio circuits?
« Reply #5 on: November 26, 2020, 09:54:09 AM »
just chipping in to give a big thumbs up to those two books.
Plus Jensen app notes and RANE stuff too.

The RANE stuff is great aswell, they disappeared from their website since Rane was bought by who cares who, but you can still find them online, I bought a book that contains all application notes and articles written by Dennis Bohn from Rane

Edit: I just checked and there are some Rane notes back in their new site, don't know how many are missing thou.
« Last Edit: November 26, 2020, 10:15:59 AM by Dualflip »

Adam_C

Re: Getting started with audio circuits?
« Reply #6 on: November 27, 2020, 04:03:25 PM »
Thanks ever so much for the responses everyone! Greatly appreciated.

Sorry what I meant about sending audio and returning is would it be safe to use say a 2i2 to output audio and return it to an input? Or would there be any risk of potentially frying something? I would be less concerned about the interace itself as it is starting to fail anyway but I wouldn't want to cause damage to my pc!

I'm very interested in something like the 500 series Studer 169 EQ that was posted in here a while ago (https://groupdiy.com/index.php?topic=36522.0) although I think it would be nice to add switchable high and low shelf values. I think I have the necessary knowledge to do that part, so would be good to get stuck in with something already made to get an idea of how things work.

Would anyone be able to suggest some sort of order in terms of sourcing compenents to stick on a breadboard? Are there any places that can provide various resistors, capacitors, op-amps etc as a set to get experimenting with things? Or is the best idea to make a circuit design and source parts once that's done?

Thanks again everyone!

Whoops

Re: Getting started with audio circuits?
« Reply #7 on: November 27, 2020, 09:20:24 PM »
Sorry what I meant about sending audio and returning is would it be safe to use say a 2i2 to output audio and return it to an input? Or would there be any risk of potentially frying something? I would be less concerned about the interface itself as it is starting to fail anyway but I wouldn't want to cause damage to my pc!

I'm sorry but seems contradicting with your first sentence in the first post "I've studied electronics for a couple of years during my audio degree"

Sending audio out from a soundcard into a circuit audio input, and audio out from that circuit into an audio line input of the soundcard how could that ever damage your PC?

The only thing you have to avoid is using a Microphone Input on your soundcard because if you turn on Phantom Power you could Damage the output of the circuit you tested. Use always Line Inputs only.

Are there any places that can provide various resistors, capacitors, op-amps etc as a set to get experimenting with things?

Any electronics component stores... google is your friend also

Banzai
Farnell
Mouser
Digikey
RS components

Ebay

Your local electronics store


squarewave

Re: Getting started with audio circuits?
« Reply #8 on: November 27, 2020, 11:16:51 PM »
I'm sorry but seems contradicting with your first sentence in the first post "I've studied electronics for a couple of years during my audio degree"

Sending audio out from a soundcard into a circuit audio input, and audio out from that circuit into an audio line input of the soundcard how could that ever damage your PC?
My QA400 has a prominent warning on it that reads "Max Input +6dBV". Driving a conventional sound card input really hard with a low impedance (like a speaker out) to a high level might not be a great idea. It should have protection diodes but they're probably low power. If the source impedance was really low you could fry something.

The only thing you have to avoid is using a Microphone Input on your soundcard because if you turn on Phantom Power you could Damage the output of the circuit you tested. Use always Line Inputs only.
True but the issue also applies to the mic input being damaged. Specifically, if the mic input has big coupling caps charged to 48V, if you plug in a low impedance output, that effectively grounds the + side of the caps and causing them to discharge into one or both the mic input transistors and output. However, any vaguely modern gear has build out resistors on outputs and protection diodes on mic inputs.

Adam_C

Re: Getting started with audio circuits?
« Reply #9 on: November 28, 2020, 09:20:13 AM »
I'm sorry but seems contradicting with your first sentence in the first post "I've studied electronics for a couple of years during my audio degree"

Sending audio out from a soundcard into a circuit audio input, and audio out from that circuit into an audio line input of the soundcard how could that ever damage your PC?


Funnily enough studying only 1 module of electronics amongst theory of acoustics, digital signal processing, and much much more means it would be useful to ask questions on things I'm not confident with on maybe say, some sort of forum?  ;)

In all seriousness I honestly loathed electronics when having to sit through lectures and whatnot, however since going on placement year in a studio, being able to read about electronics as a hobby in my free time is much more appealing. It definitely was not my strongest subject!


Whoops

Re: Getting started with audio circuits?
« Reply #10 on: November 28, 2020, 10:51:38 AM »
My QA400 has a prominent warning on it that reads "Max Input +6dBV". Driving a conventional sound card input really hard with a low impedance (like a speaker out) to a high level might not be a great idea. It should have protection diodes but they're probably low power. If the source impedance was really low you could fry something.
True but the issue also applies to the mic input being damaged. Specifically, if the mic input has big coupling caps charged to 48V, if you plug in a low impedance output, that effectively grounds the + side of the caps and causing them to discharge into one or both the mic input transistors and output. However, any vaguely modern gear has build out resistors on outputs and protection diodes on mic inputs.

Your text is a bit irrelevant when the OP question was if you could "damage the PC"!
And my reply which you quoted was related to his question.

I have yet to see someone thats has damaged their PC because they sent the wrong signal to their USB soundcard input.
And you are experienced so you know what I mean

Whoops

Re: Getting started with audio circuits?
« Reply #11 on: November 28, 2020, 11:00:05 AM »
Funnily enough studying only 1 module of electronics amongst theory of acoustics, digital signal processing, and much much more means it would be useful to ask questions on things I'm not confident with on maybe say, some sort of forum?  ;)

In all seriousness I honestly loathed electronics when having to sit through lectures and whatnot, however since going on placement year in a studio, being able to read about electronics as a hobby in my free time is much more appealing. It definitely was not my strongest subject!

There's people here with all levels of knowledge, there's no problem with that, the community still helps people out like we are all doing in this thread.
When I first started here I also knew much less than I know today and Im still learning a lot everyday.

Saying this, you have to understand that your questions are under the basic knowledge most people have.
Someone that "studied electronics for a couple of years during my audio degree" would not ask those type of questions, so it was actually contradicting and misleading like I told you before .
You had "1 Module" only and you "honestly loathed electronics when having to sit through lectures".
Basically you haven't learned much during lectures and you want to learn more now, no problem with that but with this honest info its much more easier for us to help you out and give you better advices and also understand your questions.

Best Regards

squarewave

Re: Getting started with audio circuits?
« Reply #12 on: November 28, 2020, 01:01:34 PM »
Basically you haven't learned much during lectures and you want to learn more now
If you're just going to be brow-beating people then I have no problem telling you that you have a tendency to add unnecessary noise to a lot of your posts Whoops. There was basically no helpful information in this post at all.

Re: Getting started with audio circuits?
« Reply #13 on: November 28, 2020, 02:53:18 PM »
If you're just going to be brow-beating people then I have no problem telling you that you have a tendency to add unnecessary noise to a lot of your posts Whoops. There was basically no helpful information in this post at all.

Completely agree, he is a new forum member and its not Whoops place to lecture him.

Whoops

Re: Getting started with audio circuits?
« Reply #14 on: November 28, 2020, 04:48:41 PM »
I was the first person to offer help in this thread, and I gave advice to Adam_C in all my posts.

I tried to understand the knowledge a new member has because his posts seem to be contradicting, and knowing that can also help us in helping him out, something that we do for free because we like and because we are a community.

I don't know you Squarewave or Dualflip and I dont think we have or had any personal problem, but if we do please contact me by pm so it can be solved.

Best Regards


 

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