# Sourcing LM308s?



## WheatAndBarley (Mar 30, 2022)

Anyone got line on some legit LM308s right now? Currently waiting for more parts for my parentheses mini so I thought I might as well try to get an actual LM308 in the meantime.


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## JamieJ (Mar 30, 2022)

I think fuzz dog may have some but they are only available if you buy their rat kit.


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## jesuscrisp (Mar 30, 2022)

Let's say it's hard these days to get legit LM308s. For the Parentheses Mini, especially with the octave on I feel like it doesn't matter that much. Either go OP07 or LM301, or leave out the compensation cap and use an LM/uA741 of sorts.


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## Big Monk (Mar 30, 2022)

thewintersoldier said:


> @fig customer on isle 3 needs assistance. Thank you for shopping at Fig-Mart for all your pedal needs. Someone will be with you shortly.



I have yet to encounter a component @fig does NOT have.


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## Dan0h (Mar 30, 2022)

When I switched out my non Lm308 chip out of my parentheses mini with a legit LM308 it was like a beam of light broke through my ceiling and there were magic harmonics screaming out of my amp. It might be in my head but I can hear a difference. The octave part aside though, as jesuscrisp is correct.


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## fig (Mar 30, 2022)

Apparently, the only ones I don't have are ones that _I_ need for a build. 
I do have an extra.

DM me if you want that mojo in a box feeling.

Edit: Just checked....about a dozen extras


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## Barry (Mar 30, 2022)

Like @fig  I stocked up when they began to get scarce! Hell, I've stocked up on stuff I've never used and may not ever, but by God I got it!


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## Barry (Mar 30, 2022)

fig said:


> Apparently, the only ones I don't have are ones that _I_ need for a build.
> I do have an extra.
> 
> DM me if you want that mojo in a box feeling.
> ...


How many Rats can one man build? before they call him a rodent!


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## lcipher3 (Mar 30, 2022)

I'll take a look - I do have OP07's


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## fig (Mar 30, 2022)

Barry said:


> How many Rats can one man build? before they call him a rodent!


I actually only have 2...one is a breadboard. I seem to recall a group buy on 308s...then I scored the NOS 83s. It just kinda happens.


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## szukalski (Mar 31, 2022)

What is the real-world difference between a LM308 and the available OP07?


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## bhcarpenter (Mar 31, 2022)

szukalski said:


> What is the real-world difference between a LM308 and the available OP07?


Absolutely nothing. 

/ducks


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## fig (Mar 31, 2022)

szukalski said:


> What is the real-world difference between a LM308 and the available OP07?


mojo

I believe one of the key characteristics of the op amp selection is the slew rate. Both the OP07 and the LM308 have a designed slew rate of 0.3V/µs, whereas a TL071 is 13V/µs.


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## szukalski (Mar 31, 2022)

Component mojo always gets lost in the mix. Finger mojo on the other hand..


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## fig (Mar 31, 2022)

szukalski said:


> Component mojo always gets lost in the mix. Finger mojo on the other hand..


I'll submit that component mojo can trigger endorphinal creativity and confidence, therefore actually improving one's musical capability. Once those peppy little peptides stroke your opiate receptors, you're off to see the Wizard my friend.
So yes Virginia, mojo IS real world.


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## mybud (Mar 31, 2022)

fig said:


> I'll submit that component mojo can trigger endorphinal creativity and confidence, therefore actually improving one's musical capability. Once those peppy little peptides stroke your opiate receptors, you're off to see the Wizard my friend.
> So yes Virginia, mojo IS real world.


So this mojo means we are absolutely not in Kansas anymore? Or Boston?


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## fig (Mar 31, 2022)

mybud said:


> So this mojo means we are absolutely not in Kansas anymore? Or Boston?


Sometimes I forget that not only are _some_ of my references obscure and/or regional in nature...they're outright OLD. 

Sep 21 1897. In answer to an eight-year old's question to _The Sun_ Editor; "Tell me the truth. Is there really a Santa Claus?"

Apropos considering the topic?


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## mybud (Mar 31, 2022)

fig said:


> Sometimes I forget that not only are _some_ of my references obscure and/or regional in nature...they're outright OLD.
> 
> Sep 21 1897. In answer to an eight-year old's question to _The Sun_ Editor; "Tell me the truth. Is there really a Santa Claus?"
> 
> Apropos considering the topic?


The Wizard of Oz isn’t old, just me, I fear. 😎

But in any case us wayward sons will carry on regardless in search of more than a feeling. ‘Peppy little peptides‘ is up to the minute, microbiologically speaking. Excuse me, I hear the faint call of my soldering iron. Must dash.


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## bhcarpenter (Mar 31, 2022)

fig said:


> I'll submit that component mojo can trigger endorphinal creativity and confidence, therefore actually improving one's musical capability.


Honestly, there really is something to be said for that. Music is subjective, and how you feel about a piece of gear often matters more than “does it sound better than X.”

Your Kemper patch probably sounds better than my amp, but dammit my amp just makes me happy in a way a modeler never will.


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## vigilante398 (Mar 31, 2022)

I use OP07 for SMD Rat builds and LM308AH (metal can) in through-hole builds. OP07 is easy to source, LM308AH I generally get from eBay. If you're seeing them in China for $1-2 a piece they're going to be fake, if the seller is in Europe and asking around $10 a piece they're more likely legit.


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## bhcarpenter (Mar 31, 2022)

Extra mojo for metal can ICs!

These should be legit, I’d think: https://www.jameco.com/z/LM308AH-Major-Brands-IC-LM308AH-Precision-Operational-Amplifier-2-to-18V-500mW_245673.html

edit: see note from Chuck below. Possibly not as reputable as I thought.


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## Cybercow (Mar 31, 2022)

FWIW . . . . this is a list of single opamps I've been compiling over the past few years . . . .

Single Op Amp PIN-FOR-PIN Equivalents/Replacements with Slew Rates & Input Types:

CA3080 - Slew = 50V/µs (OTA); BJT
CA3130 - Slew = 10V/µs; MOSFET (In & Out)
CA3140 - Slew = 9V/µs; FET
LF351N - Slew = 13V/µs; FET
LF356 - Slew = 12V/µs; FET
LM201 - Slew = variable; BJT
LM301 - Slew = variable; BJT
LM308 - Slew = 0.3V/µs; BJT
LM148 - Slew = ~0.5V/µs;BJT
LM4250 - Slew = variable; BJT
LM709 - Slew = 0.25V/µs; BJT
LM741 - Slew = 0.5V/µs; BJT
LM748 - Slew = 0.5V/µs; BJT
MC1439 - Slew = ~6V/µs; BJT
MC33171N - Slew = 2.1V/µs; BJT
MCP601 - Slew = 2.3V/µs; MOSFET (In & Out; 6v MAX)
MCP603 - Slew = 2.3V/µs; FET
MUSES03 - Slew = 35V/µs; FET (very expensive)
NE5534 - Slew = 13V/µs; FET
NJU7031 - Slew = 3.5V/μs; FET
OP07CP - Slew = 0.3V/µs; BJT
OPA134 - Slew = 20V/µs; FET
OPA602 - Slew = 20V/µs; FET
OPA1641 - Slew = 20V/µs; FET
TL061 - Slew = 3.5V/µs; FET
TL070 - Slew = 18V/µs; FET
TL071 - Slew = 13V/µs; FET

Slew-Rates below ~0.4V/µs are often detectable by the human ear. Above 0.5V/µs, all bets are off for human ear detection.

The input type has bearing also as it affects the input impedance of the device. BJT - low impedance; FET - high impedance.


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## fig (Mar 31, 2022)

bhcarpenter said:


> Extra mojo for metal can ICs!
> 
> These should be legit, I’d think: https://www.jameco.com/z/LM308AH-Ma...rational-Amplifier-2-to-18V-500mW_245673.html


I bought a tube of the DIP-8s they had and found several duds. They issued a refund. The cans from them seemed to do okay.


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## fig (Mar 31, 2022)

Cybercow said:


> The input type has bearing also as it affects the input impedance of the device. BJT - low impedance; FET - high impedance.


There's a gold nugget.


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## zgrav (Mar 31, 2022)

Barry said:


> How many Rats can one man build? before they call him a rodent!


How many parts can one man source?  Before they call him a store!


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## Chuck D. Bones (Mar 31, 2022)

szukalski said:


> Component mojo always gets lost in the mix. Finger mojo on the other hand..


good pun!


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## Chuck D. Bones (Mar 31, 2022)

Cybercow said:


> FWIW . . . . this is a list of single opamps I've been compiling over the past few years . . . .
> 
> Single Op Amp PIN-FOR-PIN Equivalents/Replacements with Slew Rates & Input Types:
> 
> ...


CA3130 - not an OTA, MOSFET input & output
CA3140 - MOSFET input
MCP601-MCP604 - MOSFET input & output. Rated for 6V max. Do not run them on 9V.
NE5534 - BJT input

BJT vs. FET input also affects input bias current which affects in-circuit offset voltage.

The opamps that have external compensation caps can have their SR reduced by increasing the comp cap.

It's not just about SR.  When opamps are driven to the rails, some of the internal circuitry saturates and how it recovers from saturation can vary significantly from one part # to the next.  This is not specified in the datasheet.


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## thesmokingman (Mar 31, 2022)

the lm108 and lm208 are probably easier to find domestically these days, mostly in metal can package ... bonus points if you find a way to use a military flat pack version


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## pcb rookie (Mar 31, 2022)

Ordered some from Banzai and received them about a month ago. I have not used them yet. Hope they are the real thing ...



			LM308N :: LF LM Types :: Chips, ICs, OpAmps :: Semiconductors :: Electronic Parts :: Banzai Music GmbH


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## Chuck D. Bones (Mar 31, 2022)

bhcarpenter said:


> Extra mojo for metal can ICs!
> 
> These should be legit, I’d think: https://www.jameco.com/z/LM308AH-Ma...rational-Amplifier-2-to-18V-500mW_245673.html


I would not trust anything from Jameco.


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## bhcarpenter (Mar 31, 2022)

Chuck D. Bones said:


> I would not trust anything from Jameco.


Oh really?!? Well shoot. I thought they were reputable.


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## Chuck D. Bones (Mar 31, 2022)

PM @Kpedals and ask him about his dealings with Jameco.


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## Feral Feline (Mar 31, 2022)

mybud said:


> So this mojo means we are absolutely not in Kansas anymore? Or Boston?


No, man, you're in Chilliwack...






or maybe Toronto...







No, not ...






Nor ...


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## Cybercow (Apr 1, 2022)

Chuck D. Bones said:


> CA3130 - not an OTA, MOSFET input & output
> CA3140 - MOSFET input
> MCP601-MCP604 - MOSFET input & output. Rated for 6V max. Do not run them on 9V.
> NE5534 - BJT input
> ...


Thanks for the corrections.


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## Matmosphere (Apr 1, 2022)

OP, are you in the states or Europe, or elsewhere. If you are in Europe I might know a guy that has some metal can ones.


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