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Old 28th January 2012, 09:12 PM   #11
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Originally Posted by pacificblue View Post
Most of them are only specified as 8 Ohm stable, too.
That's what would be deterring me from using them. (I'm in 4 ohm land.) Even more so in a BTL configuration, unless supplies had to be unusually low for some reason.

Hybrids like STKs can provide more output power than conventional chipamps (which are ICs). Their reliability record wasn't all that great though (with Technics' modules enjoying a noticeably better reputation), so after using a lot of them in the late '70s to mid-'80s, manufacturers gradually went back to more robust discrete designs. You may still find hybrids in low-end A/V receivers, though even there they're not as popular any more.
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Old 13th March 2012, 12:44 PM   #12
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hi, im using an stk 4050 amp, i built this circuit: STK4050 STK4050V 200W Power Amp IC - Buy Online @ AmpsLab Seems the gain is a bit low....how would i increase it?
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Old 2nd April 2012, 03:23 AM   #13
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look at datasheet an find application notes, these are some explanation to fix that.
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Old 19th February 2013, 11:22 PM   #14
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you can play into gain block of the STK, some resistors and caps can be changed of it value to get them
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Old 19th February 2013, 11:31 PM   #15
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Originally Posted by pacificblue View Post
Right, LM and TDA are prefered. Not because they are objectively better, but they have better marketing, especially thanks to third parties, who make money from them. They are easier available, and they are usually cheaper. Also the documentation takes less effort to find and understand.
Im disagree with you, STK is the most reliable and less expensive power amplifier that would be make on thick film substrate, it's an power hybrid IC amplifier, Never can be displaced of any and all or monolytic IC yesterday and tomorrow, that's a fact.
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Old 20th February 2013, 12:10 AM   #16
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I'd like to chime in here about older Sanyo STK ICs:

I have recently been using an amp board that is populated with members of the series STK41x1v where 1<x<9, the lower number e.g. STK4111v has very low output power while the "9" version STK4191v is rated at 50W+50W into 8 ohms (it's a 2-channel amp IC). I redesigned the power supply, moving it off of the amp board and using larger caps, CRC filtering, and a better rectifier. The distortion levels are respectable, although not as low as LM series amps, e.g. LM3886, especially above 1k Hz, but low enough to be a non-problem.

I have used the "9" chip into 4R loads and it seems to be fine, and doesn't generate all that much heat. I could likely increase the rail voltage, which is around +/-34VDC.

The sound is good, and I am planning to do more of these amps. I've already picked up a stock of them from Ebay, and they seem to be genuine (as advertised).

Not all STK chip amps are good - some have high distortion, but this series seems to have good sound and can be had for "cheap". Good for DIY use for sure!

-Charlie
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Old 20th February 2013, 01:02 AM   #17
Jay is offline Jay  Indonesia
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Originally Posted by Ferchito View Post
Im disagree with you, STK is the most reliable
Just be careful not to short the output. All other chips that I have used, can get away with output short. It is difficult to prevent the short when you do the prototyping. Expensive STK amp will provide relay protection tho.
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Old 20th February 2013, 01:08 AM   #18
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From the STK4191v datasheet:

Available time for load short-circuit (VCC =35.5V, RL = 8R, f = 50Hz, PO = 50W): 2 seconds

There is no protection per-se in the circuit, so you have 2 seconds (give or take) to save the amp from destruction. This is a small but important window of time, enough to pull those sparky wires apart...

-Charlie
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Old 20th February 2013, 01:10 AM   #19
Jay is offline Jay  Indonesia
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Originally Posted by CharlieLaub View Post
The distortion levels are respectable, although not as low as LM series amps, e.g. LM3886, especially above 1k Hz, but low enough to be a non-problem.

Not all STK chip amps are good - some have high distortion, but this series seems to have good sound and can be had for "cheap". Good for DIY use for sure!
THD doesn't correlate well with possible sound quality.

For STK, the "II" series has high distortion compared to the "V" series. If I'm not mistaken, they differ only in that the "V" series use a current mirror for the LTP. Current mirror can lower the THD but I think to some extent it "ruin" the sound. Some other STK with very very low THD implement cascode in the VAS. Same issue, the cascode doesn't always bring justice to the sound.

If you check the "history", those low distortion STKs have never got popularity. This will tell you something about sound perception.
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Old 20th February 2013, 01:34 AM   #20
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Originally Posted by Jay View Post
THD doesn't correlate well with possible sound quality.

For STK, the "II" series has high distortion compared to the "V" series. If I'm not mistaken, they differ only in that the "V" series use a current mirror for the LTP. Current mirror can lower the THD but I think to some extent it "ruin" the sound. Some other STK with very very low THD implement cascode in the VAS. Same issue, the cascode doesn't always bring justice to the sound.

If you check the "history", those low distortion STKs have never got popularity. This will tell you something about sound perception.
You seem to know these well - they use the current mirror. FWIW, they sound fine to me.
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