[2470] Fake LM308

Date: December 13th, 2018 | Comments : [4] | Categories: DIY.

Fake LM308 in a Mooer pedal… well, not an original National Semiconductor chip anyway.

So, is it a fake if you mark a plain cheap op-amp that meets or exceeds the specs of the original LM308 with that part number but the internal circuit is not the same?

It will work in circuits designed for the LM308 and perform well. It does the job. But at the fringes and limits of the electrical characteristics where many fx pedals operate, it will not be the same as an IC with the internal circuit design of a real original NatSemi LM308. Is that a fake or just a poor substitute?


4 Responses to “Fake LM308”

[786098] dMac Says: 2:44 pm, December 13th, 2018

I just know I’m going to cop some stick for this… I’m a realist, but also a tiny bit educated (thanks to you, Jack!)

Firstly, just because it’s a substitute doesn’t make it a poor substitute- only results will determine that…

Did it say on the box “contains genuine NS LM308”, or did you have to go looking?

If it is passed off as a genuine NS chip, I have issues. Without any statement on the box or advertising, Mooer put out an order for chips, and the ones they got were so marked. If it’s in a $30 pedal, etc, I know it’s not a NS, and the people lining up to buy it who aren’t going to take off the base plate aren’t going to expect one either- or care. And if it had a spot of back nail polish on it- would I be typing this?

But if I was paying $500 for it and it was so advertised, it had better be original.

I’m going to be controversial. What is the end result difference between the two? People may say you can hear the difference between them by A/B-ing or scoping them. That may be true- but if you need to A/B or scope them, then that difference isn’t that great, and (for my purposes) the audience on the floor isn’t going to care.

As always- thanks, Jack (please don’t be mad with me!)

[786101] admin Says: 7:15 am, December 14th, 2018

David, I agree with you. Mooer doesn’t know or care if the chips are originals as long as they have the right part number.

Did a chipmaker duplicate the original Rubylith masks for the original LM308? Not very likely.

If the alternate source LM308 chip meets the minimum specifications for an LM308, then it is a valid substitute… EXCEPT for pedal gearheads that assign special properties to the vintage LM308. (BTW, with the right test equipment, you can tell the difference in LM308 chips and the fakes.)

Lastly, the OP-07D used in the Rat2 is close to the LM308 is specs and the Proco guys did a good job of picking a substitute chip when they had to make the switch. If I got them labeled as LM308, practically no one would be able to tell the difference (without a lot of test gear).

[786234] Darron Thornbury Says: 6:15 pm, January 28th, 2019

I think if it’s coming from a source like MOUSER or RS Components, then I don’t call it fake. Since I trust those guys to do auditing that the parts are up to par. Sure, I might be a little disappointed it’s not the original brand name I know. But then, how many factories would that brand work out of, or license with anyway. But if they were from eBay or China though… lol.

If we accept a lot of it is coming from the same parts of Asia now, then really it’s the brand name reputation that I purchase on.

If there’s any chance of something going wrong then I like to do whatever I can to avoid it. If a pedal ever had to be returned it would just feel horrible and be an expensive endeavour to repair and return it which cuts into the profit margins of building and selling it in the first place.

I know DIY’ers love being thrifty and getting in on cheap deals. It’s good if you’re just doing an experiment anyway. And if you need to get every little part posted in then that’s a way to save. But Mooer would be buying bulk!

I used to always try to get the brand names. Fairchild, Texas Instruments, National Semicondunctor etc. But slowly they are disappearing to new Asian countries, who are doing a really, really good job. A lot of this I guess is due to through-hole technology becoming unpopular. If the noise specs are good, then I guess that should be an overall indicator that they have nice clean wafers etc.

If it has the same number, then it should meet all minimum specs, right? Though I think an LM386 chip is probably one that could vary a bit from different sources, since they attract confilcting oscilation problems with different people, and we do tend to drive them to find their limits in pedals like you said, don’t we?

I used to be sceptical, but now if it’s on RS or Mouser then I normally trust the cheaper brand, sometimes half the cost. For ICs and transistors, they perform as well for me, maybe better. And often the original brand names are dropping out from building so many of our favourite THT devices which seemed so solid in the market. I’m getting used to having to brand hop 🙁

[786295] Mictester Says: 3:06 pm, March 14th, 2019

In most instances, the designers of pedals (and much other electronic gear) are constrained in the parts they’re allowed to use by the Bean Counters in their company. Each manufacturer will have a target margin for profit. They will invariably source the cheapest components that will do the job – after all a cent or two saved on each unit soon adds up to thousands on to the bottom line!

There is no real “magic” to the JRC4558 for example. Maxon only chose those ICs because they were available by the million at 99.9% of cases, part substitutions will work just as well (sometimes better!). Remember – we designers just go for the parts that we’re allowed to afford!


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