Discrete components TL071

Thread Starter

Badoumba

Joined Jun 13, 2017
5
Good evening,

For an modular audio effect, I would need to build the discrete equivalent of TL071 used as a substractor. We find a lot of these on ebay, but I can't find a schematic with proper components and values.

Thanks for any support!
 

#12

Joined Nov 30, 2010
18,217
Good evening,

For an modular audio effect, I would need to build the discrete equivalent of TL071 used as a substractor. We find a lot of these on ebay, but I can't find a schematic with proper components and values.

Thanks for any support!
Maybe the seller wants you to buy his product instead of giving away his hard work for free.
Yes, $50 seems awfully high when you can buy the chip for 50 cents. You have a choice to make. Pay the price, do the research yourself, buy a 50 cent chip, or design your circuit a completely different way.
 

Thread Starter

Badoumba

Joined Jun 13, 2017
5
It is not the point of paying, but of DIY. To understand what I am building, playing with the values and see how these are changing my sound fx. So I could actually do the research myself, but these forums are for mutual help, aren't they? If not, why are we losing time exchanging here?
 

Papabravo

Joined Feb 24, 2006
15,095
To build the discrete equivalent of a TL071 opamp would be a major undertaking. There is nothing much to learn in doing that; it is more important that you learn how to apply building blocks to create working circuits. If your passion is to design better integrated circuits you can always do that. My point is, that you don't have to start at that level.
 

OBW0549

Joined Mar 2, 2015
3,566
So I could actually do the research myself, but these forums are for mutual help, aren't they?
OK, here's your "mutual help": a discrete op amp design, complete with a schematic (on page 3) you can use as a starting point for your design. It took all of 5 minutes of "research" to find, through Google. (If you're looking for a design that replicates a TL071 specifically, I doubt you'll find such a thing.)

Good luck.
 

RichardO

Joined May 4, 2013
2,271
Here is the data sheet for the dual version of the TLo71. It has a simplified version of the schematic.

Be warned that you will have a very hard time making a op-amp from discrete components. There are two main reasons. The first is that the IC is designed for matched components. The second reason is that the physical construction of all of the individual parts significantly effects the operation of the circuit. This is especially true for high frequency performance and temperature drift.

As a final note: On a number of occasions I have tried to do this -- always with poor results.
 

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crutschow

Joined Mar 14, 2008
26,413
For an modular audio effect, I would need to build the discrete equivalent of TL071 used as a substractor.
What is a "modular audio effect" and why do you need a discrete version of an op amp to do this?
An op amp is basically a black-box gain block and any modifications you do to change sound is done with components outside the op amp, not inside it.
Do you really understand what an op amp does?
 

Papabravo

Joined Feb 24, 2006
15,095
What is a "modular audio effect" and why do you need a discrete version of an op amp to do this?
An op amp is basically a black-box gain block and any modifications you do to change sound is done with components outside the op amp, not inside it.
Do you really understand what an op amp does?
Was that a rhetorical question?
 

DickCappels

Joined Aug 21, 2008
6,965
upload_2017-6-14_10-46-40.png

Apparently there are 10 transistors on this module. While I counted 16 in the simplified schematic in the TI and ST datasheets. That means that it is not a copy but something that performs in a similar manner.

There are plenty of discreet audio amplifier designs on the internet that you could choose as a starting point.

Perhaps you would find ordering a kit, which probably includes a schematic and parts list (and a circuit board) which would make a pretty good starting point (see link below)
http://www.fivefishstudios.com/diy/doa17/

edit:
The schematic, parts list and assembly instructions are in the pdf file at this link


There appears to be some sort of "discrete components are superior to integrated circuits"... (some text removed for clarity). For a good laugh, read this.
Certainly the author must be kidding. (From OBW0549's link:)

"These micro components are chemically formed and inferior in every way to even the cheapest of discrete components. (see below for more) Furthermore, even Wikipedia knows that IC opamps were created for the PC industry..."
 
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Thread Starter

Badoumba

Joined Jun 13, 2017
5
Thanks for the above links.

The audiophool I am (I take this as a nice welcome for my first post here) who is certainly not the electronics expert you are likes sometimes to build from kits and was trying to get a little more in depth with this project. And yes, many posts/websites/forums, including fivefishstudios first page claims that discrete components are of better quality in terms of noise, reaction time or whatever criteria you know better than me. Some modular effects makers like Lee Jackson claims the same. This was the primer intention of this post, trying to investigate if it was worth playing around with a components version.
 

OBW0549

Joined Mar 2, 2015
3,566
...many posts/websites/forums, including fivefishstudios first page claims that discrete components are of better quality in terms of noise, reaction time or whatever criteria you know better than me. Some modular effects makers like Lee Jackson claims the same.
I lump all of that stuff under the category of "voodoo electronics", along with junk such as "pre-conditioned" speaker cables and "cryogenically treated" speaker cables. Such things are based on ignorance and blind faith, not empirical evidence. They are, literally, a form of religion; and the people who are pushing that stuff are nothing more than con artists in the business of conning gullible rubes into giving them their hard-earned money.

But enough of that rant...

This was the primer intention of this post, trying to investigate if it was worth playing around with a components version.
There's absolutely nothing wrong with trying to build a discrete component op amp for learning purposes; you can learn a lot from that. But DO NOT expect wondrous, magical things from it, or amazingly superior audio; if you do, you'll be sorely disappointed.
 

Thread Starter

Badoumba

Joined Jun 13, 2017
5
@OBW0549
I understand your point and you are probably right about this. There's a lot of business around the NOS components for instance, most of the time of poorer quality than the new ones.

I was not sure about this possible quality difference but you and the others made it clear. So let's pick the best quality IC and surrounding components then!

Thx
 

crutschow

Joined Mar 14, 2008
26,413
There appears to be some sort of "discrete components are superior to integrated circuits" movement among audiophools. For a good laugh, read this.
That is indeed hilarious.
I've never before read so much electronics drivel on one page.
And that flimflam man is apparently making money from it.
Perhaps they should go back to an acoustic phonograph, where there's no electronics at all between the record and the sound out. :rolleyes:
 
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