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Chip Amps Amplifiers based on integrated circuits

Chip-amps suited as power stage in a composite amplifier, LM1875/TDA2050 excluded.
Chip-amps suited as power stage in a composite amplifier, LM1875/TDA2050 excluded.
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Old Yesterday, 08:05 PM   #81
FauxFrench is offline FauxFrench  France
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Originally Posted by maxhifi View Post
I was thinking about those kits too. I also looked through the Philips semiconductor handbook to see if there are other comparable ICs, with different names. The answer is not really.

It is surprising to me how it is almost always possible to track down 70 year old vacuum tubes, but a 20 year old IC is absolutely unobtainable.
Vacuum tubes still have a market among enthusiasts. Though the volume is limited, I guess the enthusiasts pay good money for the right quality. I know very little about vacuum tubes but my impression is that just by visual inspection you get a good impression if a vacuum tube is a serious product or not.

Elderly chip-amps seem different. There is no strong feeling of enthusiasm for them and the few sold are probably for casual repair. Admitted, newer chip-amps that perform closely as good as a TDA1514A (or even better) exist, they are just not pin compatible. I am certain that somewhere there are spare stocks of TDA1514, I just don't know where and the numbers are probably limited. Visual inspection of ICs is of no use and the ones I bought for a modest price at least look very Philips-like. Inside, they are hardly even discarded TDA1514 production as my specimens did not behave like TDA1514 in any datasheet sense. They appear to be plain scam-products.
These ICs did not cost me much, the test-board was quick to assemble and I can tell other forum members about my findings. They served a purpose after all though not what I hoped. I am pleased, as Turbowatch2 writes, that I did not start constructing a serious amplifier and late in the project realized that my TDA1514 ICs were useless.
A treasure hunt for the last genuine TDA1514 is hardly worth the effort and those easy to buy are most likely nothing but poor fire-crackers. Let's keep the good reputation in the past of genuine TDA1514 in our minds and let the fakes remain with a few Asian shops.
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Old Yesterday, 08:11 PM   #82
Kay Pirinha is offline Kay Pirinha  Germany
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Quote:
Originally Posted by FauxFrench View Post
I know very little about vacuum tubes but my impression is that just by visual inspection you get a good impression if a vacuum tube is a serious product or not.

No, not necessarily so. Decades ago I bought some KT88's that were made by the Shuguang factory. They looked very similarly to the G.E.C. ancestors, but eventually turned out to be exactly the firecrackers Chinese tubes were/are famous for.
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Old Today, 08:37 AM   #83
Turbowatch2 is online now Turbowatch2  Germany
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Yesterday I connected a cheap, but quite well made LM3886TF board for a basic test. Price was €8 including P&P from China. Compared to the data sheet the values of the parts are reasonable.

To my surprise nothing bad happened.
Even as my bridge rectifier had a fault and I powered it up with only one rail a few times, it survived. The real LM3886 is supposed to do so.
With input short the open output measures 1mV, which is much less than I expected. A test speaker showed no on/off sound at all. There is a faint hiss if I hold the speaker to my ear.
I can not say anything about sound quality, as I have only one board, but it simply plays music. Maybe I find the time to do some measurements.
So far I can not proof the LM3886TF is fake or real, because of the price I expected a fake chip, but it looks OK.
The 30W power supply is nothing fancy, just a few capacitors with C-L-C filtering, +- 25V DC with amp at idle.
Attached Images
File Type: jpg LM3886TF_mono1.jpg (618.0 KB, 22 views)
File Type: jpg LM3886TF_mono.jpg (994.0 KB, 21 views)
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Old Today, 08:45 AM   #84
FauxFrench is offline FauxFrench  France
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Many thanks for the information, Kay. As a boy, I used to take vacuum tubes out of old radios and study the constructions inside. I still have a box of tubes somewhere. Various electrodes, gitters etc...
Today there are still "producers" that can't make 50-60 years old technology work .
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Old Today, 09:03 AM   #85
Turbowatch2 is online now Turbowatch2  Germany
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Vacuum tube production was continued in China and Russia, because they prepared for a nuclear world war. Tubes do survive EMPīs that grill any transistor or diode.
So there is really nothing friendly in them producing tubes...
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Old Today, 09:05 AM   #86
FauxFrench is offline FauxFrench  France
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Young (no, actually not at all) and naive, I bought a couple of years ago:
* An LM1876 board that worked fine.
* Two cheap TDA7293 boards of which one had a defect TDA7293 chip.
* A TDA7850 board that worked fine.
* TDA 7377 and TDA7388 ICs that worked fine.
* A very cheap TDA7297 board that worked well.
* A very simple TDA2030 board that actually worked.

Luckily it is not always that such purchases are "loosers". It's a gamble what you get and where you sometimes loose. As long as you do not put in much money and can accept loosing.........
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