I did some more testing and this time I used the variac to keep the voltage steady at +-30 and +-28 VDC.In the previous test I didn't compensate for the roughly 5 volts of sag when driving the load.
Using a 1k signal and a 4ohm load and 30 volt rails,THD reached the 1% mark at about 88 watts.THD was .01% at 83 watts.
using 28 volt rails the 1% mark was reached at 79 watts and the .01% was 73 watts.
Not bad and I believe the results indicate these chips are the real deal and not the counterfits.
The lack of gain at hi frequencies is still a mystery.I suspect it's either the 47p cap between the inverted input and output or the 220p,between the inverted and noninverted inputs.It's not an issue for me as this will be used for the woofer section in an active speaker operating in the 60-300hz range.
Interestingly when operating a single chip the heat sink temp rose rather quickly,whereas with the 3 in parallel less heat was apparent.I quess this is due to the load being shared among the 3 chips.Im thinking this would allow for the higher of the two rail voltages to be safely used ?
Using a 1k signal and a 4ohm load and 30 volt rails,THD reached the 1% mark at about 88 watts.THD was .01% at 83 watts.
using 28 volt rails the 1% mark was reached at 79 watts and the .01% was 73 watts.
Not bad and I believe the results indicate these chips are the real deal and not the counterfits.
The lack of gain at hi frequencies is still a mystery.I suspect it's either the 47p cap between the inverted input and output or the 220p,between the inverted and noninverted inputs.It's not an issue for me as this will be used for the woofer section in an active speaker operating in the 60-300hz range.
Interestingly when operating a single chip the heat sink temp rose rather quickly,whereas with the 3 in parallel less heat was apparent.I quess this is due to the load being shared among the 3 chips.Im thinking this would allow for the higher of the two rail voltages to be safely used ?
I have used about 10 of these chips in one project and noticed that they were all marked quite 'clumsy'. However, they all worked without a hitch and sounded just as described in various posts here.
From Peter Daniel's post it is clear that the earlier versions were not laser marked and only the later lead-free ones are.
From Peter Daniel's post it is clear that the earlier versions were not laser marked and only the later lead-free ones are.
I got a reply from National semiconductors and they were no help, basically saying whoever supplied the chips should be able to tell me if they are fake or not.
To guarantee genuine chips you should buy them through authorised suppliers.
That's a lot of help. It would seem that National aren't willing or can't identify fake chips by looking at them.
The insulated chips in the photo I believe are genuine, but the uninsulated ones I suspect to be fake, as they are the ones that sound very average.
To guarantee genuine chips you should buy them through authorised suppliers.
That's a lot of help. It would seem that National aren't willing or can't identify fake chips by looking at them.
The insulated chips in the photo I believe are genuine, but the uninsulated ones I suspect to be fake, as they are the ones that sound very average.
brianco said:
What on earth do you expect? Buy a cigar from a street trader and query its quality from Davidoff? Absolutely unreasonable to expect help.
What do you mean?
What is unreasonable?
To ask National if they can identify whether the chips are fake?
How is this unreasonable?
All the posters that have had ignorant comments, like "what do you expect" or comments to that effect or otherwise unhelpful posts have ignored the Opening Post.
"can anyone identify these as being fake?
And what is the best method for identifying fake LM3386's?"
That is all.
And the end result is it is impossible to identify them as fake.
I have my answer, the moderator can close this thread is he wishes. I or anyone else wishing to know the answer to the OP has no more information to be gained from this thread.
I am with Scrappy
I would think NS would be more than willing to help identify fake chips based on their design.
Only thing unreasonable was their response, and brianco.
I have asked for help in here identifying fake 2SA1943/2SC5200. I had many helpful responses. In the end I broke a pair open. and posted pics. They looked real and worked great... and I was very grateful for the help.
I would think NS would be more than willing to help identify fake chips based on their design.
Only thing unreasonable was their response, and brianco.
I have asked for help in here identifying fake 2SA1943/2SC5200. I had many helpful responses. In the end I broke a pair open. and posted pics. They looked real and worked great... and I was very grateful for the help.
The fakers would not make a lot of money, if their fakes could be identified by simply looking at them.Scrappydoo said:
They sure are interested in identifying fakers and shut them down. Yet their response is reasonable. Tracing fakes usually takes you to a country that for economical reasons is not interested in helping to shut the faking business down. Therefore the people at National and many other companies are not willing to waste too much money and effort on even trying anymore, because it leads to nothing. Instead they build up a controllable supply chain and that is, where authorised dealers come into play. The answer they gave, makes sense, when you look at it from that perspective.john65b said:
Hi, may I share my experience when buying LM3886.
In my country, there is a big electronic parts market. You can easily find any parts there, of course with competitive price. Once I want to buy LM3886, the seller give me an option weather the fake or the original, of course with a little bit cheaper from the original one (about 25% cheaper). But the most shock I get when they shown the chips are both of them is no difference! Even when I ask them they can not indentify the difference. They just said that those chips are delivered from different supplier and they put in different rack. I am really afraid that if there is any seller is cheat, they can sell the fake with original price.
Because of that matter I change my project to LM3875 which the chips have no fake version (based on the seller’s opinion and one of the expert on there).
In my country, there is a big electronic parts market. You can easily find any parts there, of course with competitive price. Once I want to buy LM3886, the seller give me an option weather the fake or the original, of course with a little bit cheaper from the original one (about 25% cheaper). But the most shock I get when they shown the chips are both of them is no difference! Even when I ask them they can not indentify the difference. They just said that those chips are delivered from different supplier and they put in different rack. I am really afraid that if there is any seller is cheat, they can sell the fake with original price.
Because of that matter I change my project to LM3875 which the chips have no fake version (based on the seller’s opinion and one of the expert on there).
Hi,
How could you guess that glodok harco is the place I’ve mention above?! But it is true, hahaha because no others place like it right?!
Actually I just checked the received note from the seller, but there is no name mentioned on it.
I try to direct the shop to you now.
If you know Ayung’s shop, and it’s on your left, you will go forward and find the two directions. Please turn left and you will find the two shop merge into one on your left. That is the shop! They sell many electronic parts and accessories.
Hope my explanation will help you.
How could you guess that glodok harco is the place I’ve mention above?! But it is true, hahaha because no others place like it right?!
Actually I just checked the received note from the seller, but there is no name mentioned on it.
I try to direct the shop to you now.
If you know Ayung’s shop, and it’s on your left, you will go forward and find the two directions. Please turn left and you will find the two shop merge into one on your left. That is the shop! They sell many electronic parts and accessories.
Hope my explanation will help you.
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