Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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.
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th March 2020, 05:56 AM   #71
maxhifi is offline maxhifi  Canada
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by Turbowatch2 View Post
OK, I see. The 1514A might be a nice chip, but hunting for one that works might only bring up some pin compatible chip, with a totally different die inside. The Chinese faker is really creative in producing worthless junk from valuable raw material.

Found the fire cracker FF is using, even with "matching numbers":

1pcs/lot TDA1514A TDA1514 ZIP 9 50W In Stock 50 W high performance hi fi amplifier|Performance Chips| | - AliExpress

The TDA7293 is not easily compared to the LM3886. It is a quite different concept. Have a look at both data sheets. The suggested ways of paralleling the chips are very different. The "high power" option with external transistors is not very elegant. It makes the use of MOS transistor stages inside the chip seem questionable, if you extend them with bipolar ones. I do not expect very high end sound from such an combination.

It´s "advantage" to allow higher supply voltages is none, as you are limited by the heat transfer, chip to heat sink. Except you want to use 16 Ohm speaker.

To me it seems more a nice chip for OEM solutions, where you might use it to cut cost´s.

As I mentioned, the A/B stuff is dying out faster than the dinosaur´s. Getting harder to find something that is going to stay and no new development any more.
All Bruno´s fault. Shame on him!

I agree totally about MOS devices being questionable. My comment about the higher voltage limit being useful assumes multiple parallel devices, to limit the current each device is delivering to within ratings. For one single IC and a normal 8 ohm speaker I agree it is of little consequence. I also do not like the design with the so called helper transistors - why not just build a fully discrete amp in this case? Maybe you are right that the 3886 is the best on the market,

I think you're also correct that it is likely not worth it to hunt for obsolete parts, or make a new design using them. It really amazes me how much trouble the Chinese companies go to to make fakes, and in this case sadly just junk. I was hopeful that FF would have luck with those 1514A, it is too bad it ended up being junk.
  Reply With Quote
Old 26th March 2020, 07:10 AM   #72
edbarx is offline edbarx  Malta
diyAudio Member
 
Join Date: May 2018
Quote:
Originally Posted by maxhifi
I also do not like the design with the so called helper transistors - why not just build a fully discrete amp in this case?
What is wrong with hybrid designs? The goal of such designs is often of taking advantage of different technologies. So, in the case of an amplifier, the input and VAS would take the form of an IC, and the driver and power stages would be discrete.
__________________
The existence of regulations and rules is frequently referred to by manipulators.
  Reply With Quote
Old 26th March 2020, 08:55 AM   #73
Kay Pirinha is offline Kay Pirinha  Germany
diyAudio Member
 
Kay Pirinha's Avatar
 
Join Date: Oct 2011
Location: Somewhere in Germany
Quote:
Originally Posted by Turbowatch2 View Post
The TDA7293 is not easily compared to the LM3886. It is a quite different concept. Have a look at both data sheets. The suggested ways of paralleling the chips are very different. The "high power" option with external transistors is not very elegant. It makes the use of MOS transistor stages inside the chip seem questionable, if you extend them with bipolar ones. I do not expect very high end sound from such an combination.

Why not? If I get it right, the circuitry at p. 13 in the Signetics Thompson datasheet is an example of a class G amplifier with modulated higher rails (or do we call it class H?). That's not too uncommon. At lower listening levels only the chip is active.
My idea would be a combination of all three options: Paralleling two or three chips (as per p. 14), class G (as per p.13, but with more powerful external transistors, maybe MOSFETs instead of those venerable darlingtons), and BTL (not documented in the DS, external phase inversion needed). At 50-25-0-25-50 Vdc rails this would result in a very high power, though compact and efficient amplifier.
Best regards!
__________________
"I spent a lot of money on booze, birds and fast cars. The rest I just squandered." (George Best)
  Reply With Quote
Old 26th March 2020, 02:27 PM   #74
maxhifi is offline maxhifi  Canada
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by edbarx View Post
What is wrong with hybrid designs? The goal of such designs is often of taking advantage of different technologies. So, in the case of an amplifier, the input and VAS would take the form of an IC, and the driver and power stages would be discrete.
The main reason why I would be biased against a hybrid design using a special amplifier driver IC, is that over time, ICs can be discontinued, and discontinued ICs become difficult to substitute. This could end up turning the entire amplifier into a boat anchor years into the future. Functional substitutes can almost always be found for just about any discrete transistors on the other hand. If this is actually an important consideration or not depends on the priorities of the builder.
  Reply With Quote
Old 27th March 2020, 06:46 AM   #75
Turbowatch2 is offline Turbowatch2  Germany
diyAudio Member
 
Join Date: Aug 2013
Location: Northern germany
I do not have a final favorite whit all these amp chips, even as one of them seems to be in the front row.
With the chip amps that are still available, the theoretic judgement which one is the best, is a discussion with open end. Personally, I try to find the most promising one for a project. One of my mantra´s is, the most complicated amp never is the best. How much extra components are needed and what is "gimmick" is not easy to decide on.
The ideas about it may be very different. In my thinking, if a chip amp does not sound good in bare form, any add on will not make it a singer.
In the end only the finally build amp in your room compared in a listening test will decide what is best. So there are limits to the theoretical examination.
As an engineer I do not expect an amp, that measures bad, to sound good.
As an audiophile I have learned that amps, that measure very good, do not have to sound good.
The last, maybe 15, years have made it much simpler to find good sounding, cheap amp concepts. For me the once 2nd class chip amp, may it be A/B or D, has become the most attractive.
I have quite some different amps at home to compare "sound" and some amps that had a good reputation in their time just loose against today´s average amps.

Maybe a short description for "good sound" with an amplifier?
It means to me that if you use the same components at the same loudspeaker with the same program and change only the amp, there are no parts of the reproduction that start to sound wrong. Compared to a reference amp. Ignoring that a 25W amp may not have the same, brute force in the lower octave. This is the subjective, not measurable part of music reproduction that matters most for me.

30 years ago you could do this test in a few minutes and decide which amp was better. Today, with even cheap amps, things have gotten much more complicated.
  Reply With Quote
Old 27th March 2020, 10:36 PM   #76
FauxFrench is offline FauxFrench  France
diyAudio Member
 
Join Date: Dec 2017
Location: The mountains, calm and quiet.
TDA1514A

I continued a bit the testing of my TDA1514A samples without bootstrapping connected.

One specimen blew when the +/-18V supply voltage was applied.

Two other specimens did not appear to “burn” such as the four other but did not show any important reaction to supply voltage or an input signal.
One did put its output voltage close to zero but a sine-wave at the input caused no signal at the output.
Another specimen put the output voltage at around -12V. It did not react to a sine-wave at the input.

Having tested 6 out of my 7 TDA1514A ICs, and knowing from maxhifi that there are many fakes around and no supply of genuine items possible from reputed suppliers, I find it time to conclude that TDA1514A ICs bought from Asia are very likely useless. They will hardly perform even to a reduced level. Worst case they self-destruct when supply voltage is applied, best case they do not react much at all.

I terminate my testing of TDA1514A.
  Reply With Quote
Old 28th March 2020, 05:27 AM   #77
Turbowatch2 is offline Turbowatch2  Germany
diyAudio Member
 
Join Date: Aug 2013
Location: Northern germany
@FF
I´m really sorry you verified my worst expectations. I was surprised when I saw your chips still offered a dozen times at Aliexpress, all with your serial and production numbers. Which is impossible. The faker not even changed numbers after a few thousand pieces and years.
Maybe you got fakes that failed quality control
At least, in the sense of Chinese mentality they worked: You paid in valuable Euros for worthless Wuhan´s and you are unable to complain!

I expected most of them to be fake, but basically working. Maybe your design misses some tweak to let them live. If you wanted to know for sure, I would order one of the cheap kit´s with such a fake TDA1514A, as some seem to work if you look at the comments.
In my thinking, the ones you got are the best outcome, imagine they would work, you use them for a project and the resulting sound is bad, after you spent all this time and money to build an amp. You would be disappointed and think you constructed something wrong. In reality it was just because your chip was something cheap and different inside.

I start to understand why the Chinese designers fit these (theoretical) unnecessary "Speaker Protections" to the amp boards...
  Reply With Quote
Old 28th March 2020, 02:45 PM   #78
anti is offline anti  Slovakia
diyAudio Member
 
Join Date: Jun 2008
Quote:
Originally Posted by Turbowatch2 View Post
...
As an engineer I do not expect an amp, that measures bad, to sound good.
As an audiophile I have learned that amps, that measure very good, do not have to sound good.
...
It's impossible to argue with that.
  Reply With Quote
Old 28th March 2020, 05:26 PM   #79
maxhifi is offline maxhifi  Canada
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally Posted by Turbowatch2 View Post
@FF
I´m really sorry you verified my worst expectations. I was surprised when I saw your chips still offered a dozen times at Aliexpress, all with your serial and production numbers. Which is impossible. The faker not even changed numbers after a few thousand pieces and years.
Maybe you got fakes that failed quality control
At least, in the sense of Chinese mentality they worked: You paid in valuable Euros for worthless Wuhan´s and you are unable to complain!

I expected most of them to be fake, but basically working. Maybe your design misses some tweak to let them live. If you wanted to know for sure, I would order one of the cheap kit´s with such a fake TDA1514A, as some seem to work if you look at the comments.
In my thinking, the ones you got are the best outcome, imagine they would work, you use them for a project and the resulting sound is bad, after you spent all this time and money to build an amp. You would be disappointed and think you constructed something wrong. In reality it was just because your chip was something cheap and different inside.

I start to understand why the Chinese designers fit these (theoretical) unnecessary "Speaker Protections" to the amp boards...
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.
  Reply With Quote
Old 28th March 2020, 07:11 PM   #80
Kay Pirinha is offline Kay Pirinha  Germany
diyAudio Member
 
Kay Pirinha's Avatar
 
Join Date: Oct 2011
Location: Somewhere in Germany
The 6L6 tube was introduced in 1936 and is still in production 84 years later, albeit not by the original manufacturer.
Best regards!
__________________
"I spent a lot of money on booze, birds and fast cars. The rest I just squandered." (George Best)
  Reply With Quote

Reply


Chip-amps suited as power stage in a composite amplifier, LM1875/TDA2050 excluded.Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
LM1875 in parallel configuration and used in a composite amplifier. FauxFrench Chip Amps 550 17th March 2020 04:09 PM
TDA2050 vs. LM1875 for my gainclone lineup Chip Amps 11 1st May 2018 06:01 PM
Stereo LM1875 / TDA2050 PCB with Power Supply kuldeepsingh Chip Amps 35 27th May 2012 11:29 AM
Power output test LM1875, TDA2050, TDA2040 johnr66 Chip Amps 5 6th May 2011 06:28 PM
LM1875, TDA2050 on 2 Ohms johnr66 Chip Amps 6 18th February 2010 01:55 PM


New To Site? Need Help?

All times are GMT. The time now is 05:14 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki