I ask since a simple multi-meter measurement shows that they don't have the 30k Ohm resistors from Vocm (common mode voltage input) and the positive and negative supplies. A real OPA1632 was measured and the 30k resistors measured 30.7k.
If you bought one of these modules (see pictures) what noise and distortion levels did you measure? Do the modules have good noise and distortion performance or should they be disposed of?
If you bought one of these modules (see pictures) what noise and distortion levels did you measure? Do the modules have good noise and distortion performance or should they be disposed of?
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A function of the OPA1632 is the fact it contains a CM error amplifier to suppress CM signals .
Instrumentation amplifiers require a high CM rejection level , without this noise levels increase , if your IC shows an output level above TI specifications and you suspect its a cheap scam copy then I would bin it .
Noise of a real one is =1.3nV and even at 20KHz its below 0.0001 % ,now that's so low you should only hear what the input signal has in it not what the IC adds.
Notice its measured using leg 2 which is Vocm .
Instrumentation amplifiers require a high CM rejection level , without this noise levels increase , if your IC shows an output level above TI specifications and you suspect its a cheap scam copy then I would bin it .
Noise of a real one is =1.3nV and even at 20KHz its below 0.0001 % ,now that's so low you should only hear what the input signal has in it not what the IC adds.
Notice its measured using leg 2 which is Vocm .
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Well I "tested" these modules with +/-15V supplies and inputs grounded as a first little test.
The so called "OPA1632" gets burning hot. So not only are the 30k resistors missing from the supplies to the Vocm pin the modules are in fact totally useless nonfunctional junk. Of course without the internal 30k resistors there was a 0% chance that these were not fake.
Between the time I ordered them and arrival the following two negative reviews were left by other buyers. (Attached image.) I can only assume that the positive reviews were left by buyers who received the item but never tested it before leaving a review. (Or fake reviews.)
The so called "OPA1632" gets burning hot. So not only are the 30k resistors missing from the supplies to the Vocm pin the modules are in fact totally useless nonfunctional junk. Of course without the internal 30k resistors there was a 0% chance that these were not fake.
Between the time I ordered them and arrival the following two negative reviews were left by other buyers. (Attached image.) I can only assume that the positive reviews were left by buyers who received the item but never tested it before leaving a review. (Or fake reviews.)
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Thanks for the confirmation Kozard ,it would be a help if you could post the website/seller to warn others , that's what my last help website did so the public would not be scammed.
I bought them from seller ElectronicFans on AliExpress. Even with two buyers reporting that they don't work they are still selling them. That is the same thing I have seen with all the fake op-amps, fake power transistors, fake capacitors and the fake low noise regulators. They just keep selling them.
I am hoping the PCM1802 ADC and the USB to I2S module from them work better...
I imagine all the DIYMORE OPA1632 modules are the same. (They are sold by many different but "similar" sellers on AliExpress and ebay. I often wonder if the many different sellers are actually the same person/company.)
If anyone has ever used a working DIYMORE OPA1632 module please post a reply. (See photo in the first post.)
I am hoping the PCM1802 ADC and the USB to I2S module from them work better...
I imagine all the DIYMORE OPA1632 modules are the same. (They are sold by many different but "similar" sellers on AliExpress and ebay. I often wonder if the many different sellers are actually the same person/company.)
If anyone has ever used a working DIYMORE OPA1632 module please post a reply. (See photo in the first post.)
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Your intuition is right there is not a vast number of different sellers I get emails from US organisations telling me about the latest scams/viruses etc and they spent some time checking into this and one guy --are you ready for this --has been doing it for years and is now very rich he just changes IP addresses etc and name changes we are talking 100,s of 1000,s of £££££ .
He refuses to stop when one is stopped he just changes digital addresses etc and opens more up .
Tried to access it my blockers blocked it "unsafe " .
He refuses to stop when one is stopped he just changes digital addresses etc and opens more up .
Tried to access it my blockers blocked it "unsafe " .
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Do not buy anything audio related from aliexpress or ebay. Mostly the sell fake garbage. Audio is our passion not a joke!
I definitely have a long and growing list of what I will not buy anymore from AliExpress or ebay. But in someways it is tough since you can get real WM8805, ES9028Q2M, ES9038Q2M and CS4398 (at very good prices) yet so much more is fake junk. And I do like some of the kits I have bought such as the LJM QUAD405-2 kit.
But it can be a frustrating waste of time. At this point op-amps, power transistors, electrolytic caps, WIMA caps, audio caps, low noise regulators, etc, ... ...I don't want the endless problems of buying from AliExpress or ebay.
Over the last few months I have certainly learnt quite a bit setting up my LNA, notch filter and op-amp distortion testing CS4398 DAC. I really did not plan to spend so much time on it but I made the mistake of reading great reviews and taking a chance. Unfortunately I have learnt that good reviews don't mean anything. There are fake reviews I am sure. But a big problem is that many leave 5-star reviews without testing anything.
But it can be a frustrating waste of time. At this point op-amps, power transistors, electrolytic caps, WIMA caps, audio caps, low noise regulators, etc, ... ...I don't want the endless problems of buying from AliExpress or ebay.
Over the last few months I have certainly learnt quite a bit setting up my LNA, notch filter and op-amp distortion testing CS4398 DAC. I really did not plan to spend so much time on it but I made the mistake of reading great reviews and taking a chance. Unfortunately I have learnt that good reviews don't mean anything. There are fake reviews I am sure. But a big problem is that many leave 5-star reviews without testing anything.
I believe you. In past i have bought several lm3886tf and other genuine audio grade op-amps at a unbelievable price(less than half compared to rs comp or mouser), although not from aliexpress. Aliexpress is good for non critical component and cheap products but definitely not recommended for hi-end audio.