My GC STK4231-2 Subwoofer amp, should I switch to discrete? - diyAudio
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Old 25th December 2004, 07:36 AM   #1
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Default My GC STK4231-2 Subwoofer amp, should I switch to discrete?

I have an amplifier that I use to drive my subwoofer. I am considering rebuilding this amp with discrete components.

It's made by Sharp, The Chip Amp is a STK4231-2 and has two 8 ohm channels that I paralleled to make a mono amp capable of driving my 4 Ohm 12" Subwoofer. The input of this goes to the subwoofer out jack on my Surround Receiver.

The amp sounds awesome, but I was thinking that maybe going to a Discrete design with paralleled outputs may give it more power or control of the subwoofer. Also, the heatsink, is a cheap, small fancooled one, and I can put in a larger heatsink and fan instead.

The Specs on the chip say 100W/ch min and I measure 44-0-44 at the Secondary of the Transformer.

Would upgrading this to a Discrete design help any, or would it sound the same?
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Old 25th December 2004, 08:23 AM   #2
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Default stk amps 423* series

hello , im sure your sub is plenty happy with the stk amp. i had a old sharp amp with dual 4048V amps, massive power supply- heat sinks, etc....... they blew many of cheap speaker back in the day before i knew any better.

i have just recently saved a total stk rig from the trash on curb day. i got really nice trafo, psu pcb for the cd/tuner/pre-amp/remote turn on , etc....and to stk4235mk2 amps

of course the same cheasy heatsink with dinky fan as yours....... anything is better than that (check apexjr for some cheap stuff)

im pretty sure the only thing that was wrong with the system was a faulty cd changer (was a all in one Dolby Surround cheapo system)

id love to see a pic of your amp, ill try to get some pics of mine.

if you have any data sheets for yours id love to see them.......or any good stk links

ive searched for the 4235mk2 forever and never found it.... anybody have this info?
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Old 27th December 2004, 12:30 AM   #3
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So you are saying the STK chips are just as good as discrete transistor amps? I have to admit, even before I used it as a sub amp, it made a great sounding stereo amp.

I have to admit, when a chip amp blows, it's much easier to fix, because you just change the chip.

(I've already fixed this amp with a used STK4231 from a different stereo once and the STK modules are hard to find, so that was another reason I was gonna go to discrete, and also make the amp overbuilt to last long )

This amp really slams my sub, but I guess having a 44-0-44 Power transformer is what is really giving this amp it's slam.

Should I have posted this in Solid State instead of chipamps?
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Old 27th December 2004, 02:44 AM   #4
Rimband is offline Rimband  United States
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Hello guys, go to this website, you can find the PDF datasheet on your STK modules. http://www.datasheetarchive.com

Good luck, hope this helps!

Joe
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Old 27th December 2004, 08:14 AM   #5
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Quote:
Originally posted by Rimband
Hello guys, go to this website, you can find the PDF datasheet on your STK modules. http://www.datasheetarchive.com

Good luck, hope this helps!

Joe
Thanks. I checked out several datasheets.

By looking at the datasheets, it seems that the STK is not really a complete chipamp, but most of one (hybrid amp) and you set resistor values for quiescent current, input impedance, etc. It's more or less a partial discrete amp with all the transistors built inside the STK module.

Hmm, maybe going to all discrete transistors isn't the best upgrade, I was thinking instead I could add bigger filter caps, put in a bigger bridge rectifier, and upgrade the cooling fan to a better flowing computer fan, and put in a larger heatsink too, since with the one it has, I've measured temps over 60C
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Old 28th December 2004, 12:14 AM   #6
B.I.G is offline B.I.G  Romania
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If it`s not broke fix it until is !!

why don`t you leave the poor little amp alone !

60C is a very good temperature value the only way you will get more power is if u put higer supply rails but you would then have bigger problems such as over voltaging the ic, caps ....

if u really want something simple and powerful you can try to parallel/bridge some lm3886 ... i`ve paralleled TDA7294 witch i think is a more powerful ic and with only 2 of those i got about 250W on a 2ohm load ... i u bridge those you get 500W ... that`s enough for a 12 incher
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Old 4th October 2013, 05:36 PM   #7
comares is offline comares  United Kingdom
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Greetings from the Philippines.

I just finished restoring an stk4231 amp today and spent 4 hours sound testing it with a variety of speakers, and i liked its performance.
My sister have 100v hifi components with tda7295 ics which blew off after being plugged by mistake into 220volts, the standard voltage here. The circuitry looks simple and easy to build, though i also have in my options tda7293 or tda7294. In our place the tdas costs about 5 dollars, the lm3886 costs about 9 dollars. By the way there are electronic manufacturing plants in our country. We make the semicons, but then ship it to other countries so that they can put their name on it and sell it back to us, lol as my college instructors say.

I have been an electronics technician for almost 20 years, but only this year that i got interested in making really high wattage amps. Just the other day i rescued the circuit board stk4231 II power amp block from a junkyard and they sounded really nice on my 18inch Trio Kenwood speakers rated 175w continuous, 375w max rms(made dec 1982, 30 years already!)

i supplied the amp with 50-0-50 volts 5 amps. The stk4231 really packs power and clearer sound than my dx amp of c5200 and c1943 transistorr, which is rated 250+250w, which i doubt as i cannot go above 35-0-35 5 amps. A higher voltage and the resistors began to smell.

So i will be spending some more hours with stk4231. I still have about 6 stk amps to remod. Hope your amp is still good after this 9 years.
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Old 5th October 2013, 08:05 PM   #8
Minion is offline Minion  Canada
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You can try a Class D amp if its for a subwoofer and since Class D is so efficient you would get considerably more power at a given voltage ...
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