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Old 9th June 2010, 11:30 AM   #1
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Default TDA7294 versus NS

A quote regarding chip amps from Curt Wishman
Director of R&D
Integrity Research and Development Company, your comments please.

... "To the best of my knowledge there is NO "drop-in" replacement (from any IC manufacturer) for the TDA-7294V that we use in the MB-100 (and that we used in the LeAmp which was an MB-100 private labeled).

National Semi does make some amplifier ICs and we have tried them all (the first in 1996) but we didn't like the way they sounded compared to the TDA7294. They were more SS sounding (harsh) and had very bad clipping effects whever you got near their power limit. The TDAs could output more power, didn't have clipping issues, and sounded very smooth almost tube-like.

The National Semi ICs have different pin-outs from the TDA7294. NS also uses a different type of output stage. The TDA uses MOSFET outputs to achieve its very unique high-end sound.

The more expensive TDA7294 ICs can be hard to find, especially in quantity. If you read the threads at DIA you will see many mention this fact. The National Semi ICs are much cheaper and readily available. Perhaps the availability, cost, and the fact NS ICs were used in the popular DIY Gainclone is why many of the people on that website use the National Semi ICs.

The bottom line is that I don't believe there is a drop-in replacement IC for our MB-100. I also don't believe that any of the National Semi ICs sound as good as the TDA7294 ICs.
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Old 9th June 2010, 11:45 AM   #2
osscar is offline osscar  Latvia
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it is subjective IMHO. In my country genius LM 3886/3875 is more expensive than TDA7294. I`v seen more frequently blow-up TAD 7294 than the LM.
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Old 9th June 2010, 03:15 PM   #3
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Quote:
Originally Posted by osscar View Post
it is subjective IMHO. In my country genius LM 3886/3875 is more expensive than TDA7294. I`v seen more frequently blow-up TAD 7294 than the LM.
This chip is being used in the IRD MB100.
As far as I know, no blow-up has been reported as used in this amp.
As for quality of sound, as you said, ..."subjective IMHO".
Basically, what I was asking is:
A company named nOrh marketed them as Le Amp.
Those mono blocks are the exact units as the IRD mb 100 mono blocks.
I assume some here may be familiar with either units.
Since the NS chips are very popular here and with consideration of the designer,
Curt Wishman of Integrity Research and Development Company's original remarks-above, I was curious whether anyone here is familiar with those mono blocks.
Curt obviously has found that it is the implementation, as is always the case- that makes these chips superior in his design or perhaps at the target cost/build.
Comments?
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Old 9th June 2010, 10:44 PM   #4
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Quote:
Originally Posted by philmagnotta View Post

Curt obviously has found that it is the implementation, as is always the case- that makes these chips superior in his design or perhaps at the target cost/build.
Comments?
It is very much the implementation that determines the sound of these two devices, so I find I disagree with Curt that the LM3886 is intrinsically harsh. But I do agree with him about the clipping behaviour of the LM3886 - not pleasant, the TDA7294 clips more cleanly. In my experience, the TDA is cheaper; other issues are that the TDA takes slightly less quiescent power yet the packaging options of the LM include isolated mountings.
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Old 9th June 2010, 11:29 PM   #5
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Thanks for the information gentlemen.
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Old 10th June 2010, 01:07 AM   #6
Minion is offline Minion  Canada
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I believe the TDA7293 is a drop in replacement
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Old 10th June 2010, 04:55 AM   #7
sangram is offline sangram  India
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As is the TDA7295. ST has quite a few of those chips at various voltage and power handling levels (and I assume, costs).

TDA7293/4 are also among the most faked chips out there, being of primitive packaging they are easy to recreate and ST's print is also easy to copy as it looks cheap originally.

I used to build with TDA7294 but found them exceedingly fragile, even with guaranteed original chips. I built my first from a packaged Elektor kit, and one fine day one channel just blew, just like that. They shared the supply voltage so that wasn't it, the chip just died.

They sounded reasonable, but the National chips take a lot less components (the 3875 takes the smallest number of components I've ever seen in a chipamp) and sound significantly cleaner IIRC. Never clip my amps if I can help it so wouldn't know about that - but yes, the LM chips sound nasty when they reach clipping, real nasty.

And now we can't get original TDA7294s in this country anyway, so can't compare it, only fakes are available.
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Old 10th June 2010, 05:29 AM   #8
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I found a couple of TDA7293's a couple of years ago in the local market. I have not used them yet. However I have not yet burnt the 7294's that I bought. Under some circumstances I found them to be oscillating but shut it off before they blew. The heat sink was extremely hot with no signal.

How can you say they are fake ? They are not particularly cheap like most fake parts !

Would the 7293's just be a fake number on a 7294 package ? I've never seen a 7293 in the market lately.
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Old 10th June 2010, 05:29 AM   #9
osscar is offline osscar  Latvia
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I agree - even in my area lot of TDA are fakes-perhaps this explains their fragility. LM clipping on scope looks really sharp...But I also never listening so loud.
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Old 10th June 2010, 05:42 AM   #10
sangram is offline sangram  India
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@ashok - 7293 is not easily available. Nor is 7295 (the chip is used in many popular speakers - Bose Acoustimass has/had the 7294, and the Altec Lansing MX5021 uses the TDA 7265/7295 complement)

A TDA 7294 costs Rs 150 in the local market, maybe less. That's $3 - which is around the same as the large-quantity distributor price. A little odd, personally speaking, so I tend to avoid it.
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