Are these LM308N Real or... ?

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Are these LM308N Real or... ?

Postby minnow » 07 Mar 2014, 16:19

Hi friends, was sourcing for LM308N for the ultimate Rat build, and came across these:
image.jpg

Questions:
1. Can I trust those LM308Ns? They 'look' suspect
2. Is the CUE LM308 good for a Rat build?
3. Is that LM3080N a CA3080 equivalent (can I use in a Ross compressor build)?
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Re: Are these LM308N Real or... ?

Postby Dirk_Hendrik » 07 Mar 2014, 17:17

My alarm bells ring. And they're pretty loud.
I'd say avoid.
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Re: Are these LM308N Real or... ?

Postby minnow » 08 Mar 2014, 02:51

Thank you Dirk :)
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Re: Are these LM308N Real or... ?

Postby thrilli » 01 Jul 2014, 16:54

Hi,

I got a fake or not-question on LM308 chips aswell :

What do you think of these?

These were not bought from china via ebay, but do look like what the pictures show in the ads by chinese sellers on ebay.. :scratch:

here's a link to a picture posted on another forum that shows examples of LM308 variants used in rats, i found this while searching for the chips..

http://music-electronics-forum.com/attachments/26684d1387485815-nat-semi-corp.jpg

the ones that i got don't really look like any of the ones in the picture.

so would this be the a good time for a facepalm or is there any change of these chips being "real" :) ? ?

thanks!
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Re: Are these LM308N Real or... ?

Postby Tall Steve » 03 Jul 2014, 19:52

I got some that look like that from an American seller a while back. While I can't verify the authenticity of yours or mine, I'm using one in the Rat I've got on the breadboard right now. As far as I can tell, it sounds like a proper Rat should (I've never owned a real one). There's a marked difference in the midrange between it and the OP07 I bought for comparison. The OP is a lot more edgy, just like in all the comparison vids I've seen on YouTube and just like it's large signal response-per-frequency data implies. Also, the Nat Semi LM13700s I have are printed with the gold ink, swirly 'N', and no band as well. Are those 308s working all right for you?
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Re: Are these LM308N Real or... ?

Postby Dirk_Hendrik » 06 Jul 2014, 12:10

thrilli wrote:so would this be the a good time for a facepalm or is there any change of these chips being "real" :) ? ?


Cannot say. Couterfeits are hard and the counterfeiters read online as well.
Other than that I end not to trust:
1)rare and obsolete NOS IC's that have been going obsolete for quite some time
AND
2) coming from China or from a non application specific IC seller (who probably does not check for counterfeits)
AND
3) have their type number laser engraved (gold ink? ;-) ).

As you see in the link you post all examples have an ink based type number printed. Problem is that in most more linear applications (that require an opamp in general) one will not even notice the difference. Only when using the opamp out of that linear range (like, as a clipper in a RAT) one will start to notice the differences.
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Re: Are these LM308N Real or... ?

Postby thrilli » 06 Jul 2014, 17:15

Thank you for your replies Steve and Dirk!

I actually haven't started building my clone just yet, so I haven't tested them out by any means. I'll probably have the time to make the pedal within a couple of weeks. Maybe when the pedal is ready we will see if these work like a proper lm308..

I actually had a Rat years ago and it went thru a couple of changes including an IC change (from OP07 to an NE5534p if i remember correctly) selectable diodes + several other things that I can't really recall. I think i didn't fancy the sound of a Rat to much back then, and that with the mods i came to use the pedal more as an od pedal or a booster than for distortion.. Probably that is the reason I replaced it with a good od pedal. That be said, i actually have never playd a "proper" spec rat with an LM308 :roll: and as my quest for good distrotion has once again begun i though i might just give the Rat a second change.

I have lived in the assumption that the lm308s have not been produced by anyone in a while, is this correct? Google searches kinda imply so.. and judging from Dirks reply
Dirk_Hendrik wrote:Other than that I end not to trust:
1)rare and obsolete NOS IC's that have been going obsolete for quite some time
AND
that may be the case.

That would mean that all the ones currently available are baches previously unsold (NOS or otherwise), or are infact different opamps relabeld, which i think would be odd for such a cheap and narrowly used component to make faking a chip worthwhile..
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Re: Are these LM308N Real or... ?

Postby Dirk_Hendrik » 07 Jul 2014, 07:06

See my number 3 ;-)

I find that one harder to grab as well. How sure can one be that there were no versions made with laser engraved P/N's? Depends on the age of the chip.
However, when all chips seen in the real application show ink stamped P/N's and all China offered chips show laser engraved P/N's that's where my alarm bells start going off.

Apart from that I always find it very odd that stock seems to be depleted worldwide but fresh new batches of rare IC's keep on popping up in China.
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Re: Are these LM308N Real or... ?

Postby Tall Steve » 07 Jul 2014, 14:50

FWIW, I found a pdf of Nat Semi marking codes: http://www.ti.com/lit/an/snoa039c/snoa039c.pdf

I also found another post at DIY asking the same thing about 6 months ago: http://www.diystompboxes.com/smfforum/index.php?topic=105385.0. Mark Hammer's reply is that there isn't really a high demand for 308s outside of the pedal market, so counterfeiting doesn't make good business sense. The best action I guess is to breadboard them and see how they sound. On that note, I noticed that the pedal sounded MUCH better without a pull down resistor. I can't tell you why that is, but I highly recommend going without.
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Re: Are these LM308N Real or... ?

Postby Dirk_Hendrik » 07 Jul 2014, 16:49

Tall Steve wrote: so counterfeiting doesn't make good business sense.


And how much exactly does it cost to set up a new text in a laser engraving machine and convert TL071's into LM308's? Close to 0. So once thet counterfeiting machine is paid/leased/whatever everything that is ran through it is close to pure profit.

There's very little demand professionally/in large quantities for MN3005's. Almost no self respecting mfr would go that obsolesence route for a new and profitable design. Still there's loads of (suspective) couterfeits available on the bay.
Assuming no counterfeits because the market/sales is/are too small.... I wouldn't count on it. You'll get burned,
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Re: Are these LM308N Real or... ?

Postby Tall Steve » 07 Jul 2014, 19:10

Dirk_Hendrik wrote:
Tall Steve wrote: so counterfeiting doesn't make good business sense.


And how much exactly does it cost to set up a new text in a laser engraving machine and convert TL071's into LM308's? Close to 0. So once thet counterfeiting machine is paid/leased/whatever everything that is ran through it is close to pure profit.

There's very little demand professionally/in large quantities for MN3005's. Almost no self respecting mfr would go that obsolesence route for a new and profitable design. Still there's loads of (suspective) couterfeits available on the bay.
Assuming no counterfeits because the market/sales is/are too small.... I wouldn't count on it. You'll get burned,

That's a good point. I've seen the economic argument elsewhere, too, but given Mark's esteem in the DIY community, I figured his reply carried some weight. I've seen reports that some resellers re-stamp their ICs even if they are legit. For me, I think it comes down to the risk-reward ratio. Considering you can get 10 308s on eBay for what one will run you at Mammoth or Small Bear (and sometimes with free shipping to boot), the risk is more than justified in my view, at least in small quantities. I'm with you on avoiding obsolete parts in new designs, though. It kills me every time I get excited about some effect only to find it calls for a J201 in the schematic. Yet another punishment for my tardiness to effects building.

BTW, Dirk, could I PM you with some questions regarding lead-free soldering? I've been wanting to move more in that direction.
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Re: Are these LM308N Real or... ?

Postby Dirk_Hendrik » 07 Jul 2014, 20:36

No flame intended at all at Mark Hammer.

As for lead free. Sure.. If I happen to know what you need you're more than welcome :thumbsup
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Re: Are these LM308N Real or... ?

Postby Tall Steve » 07 Jul 2014, 21:41

Thanks! Mostly I'm just on a tight budget, so any guidance as to future purchases would be awesome! :D
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