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Old 14th February 2013, 02:40 PM   #11
johnr66 is offline johnr66  United States
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Quote:
Originally Posted by abraxalito View Post
Isn't TDA2030V just a particular form of lead bend on what's the same die as TDA2030A? Or am I missing something? Seems to me that amps with LTP in the input stage are always hamstrung by that. Degeneration helps though - many of the LM3xxx have resistors in the LTP.
The TDA2030 is an IC with max supply voltage of +/- 18 volts. It can be in H or V suffix for mounting position (lead bend). Not sure if it is active or not. The TDA2030A seems to be only available in the TDA2030AV vertical mount according to the ST current datasheet. The A suffix denotes a part with a supply voltage of +/- 22 volts max.
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Old 16th February 2013, 04:11 PM   #12
Jay is offline Jay  Indonesia
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If I'm not mistaken, that was the reason I didn't go with TDA7265 for my "extreme" project. TA82XX is a better candidate. But I want to try TDA2030V first because I know how good it is.
My small chip amp is an LA4270. Go search the datasheet, it doesn't have anything special. It's THD at 10K is 0.23% for 2W output. Acceptable still.

It took me two and a half day to tweak the amp for best sound. Tried several bypass cap values and brands, feedback resistor values and brands, input BJT buffer transistors, and at last it can sound beautiful enough.

So I built a TDA2030V several hours ago with basic parts. No way it can compare to my LA4270. Then I use better parts (BC/Philips for supply caps, Oscon for feedback cap, vishay 0.01% for FB resistors, Sanyo NP for input caps). Still, the LA4270 is way special.

From my experience building chip amps, it is impossible to get special sound without preamp. That's why I often use a single transistor in the input as a minimum substitute for the preamp. Haven't done this to the TDA2030V. I think TDA2030A is better than this TDA2030V.

So what chip amp next? I tried to check the datasheet for TDA7296. No way this chip can sound good. Here is a little secret of a good/bad sounding amplifier (example is a bad one, for TDA7296):
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Old 16th February 2013, 11:20 PM   #13
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Its probably the RF susceptibility of the input stage, that's the reason you find you can't get decent sound without a preamp. Try TDA8566, this is giving me the special sound without any preamp, but you do need very good PSU decoupling - ceramic caps I've found work well.

Looking at a THD vs level plot, what I think indicates bad sound is sharply rising THD at the lowest levels (<1W on this plot you're showing).
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Old 17th February 2013, 06:34 AM   #14
Jay is offline Jay  Indonesia
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Originally Posted by abraxalito View Post
Its probably the RF susceptibility of the input stage, that's the reason you find you can't get decent sound without a preamp.
I have no idea. With chip amp I prefer a lower gain as chip amp distortion is relatively higher compared to discrete amp or preamp. With lower gain the drive suffers, also the amp more easily oscillate.

High frequency issues play an important role for a good/bad sound. Much more than most people know/realize I believe.
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