STK4141 VS KTB688+KTD718

[Hakimi]

Hello, I'm new here
from my friend i got some schematic of power amplifier using KTB688+KTD718 transistor rated 45-50W. However before this i found a hobby kits of audio amplifier using STK4141 II rated 100W...
The question are :

Which is better in term of audio quality ( normal usage; Computer sound system)?

Which are durable and long lasting (over heating, short circuit)?

Best of overall, which amplifier type preferred ?

Thanks,

[mt490]

The KT* amplifier sounds like a discrete amplifier circuit using the transistors of those part numbers.

Without the schematic that you're referring to it will be very hard to produce a comparison about how well it will perform versus anything else.

[IndAudio]

As far as I have known STK 4141 can deliver upto 70W/ch at a very high distortion rate and with heavy heat sink. I hope the hobby kit does not quote 100W/ch!

[Hakimi]

Originally Posted by IndAudio

As far as I have known STK 4141 can deliver upto 70W/ch at a very high distortion rate and with heavy heat sink. I hope the hobby kit does not quote 100W/ch!

hahaha... from the hobby kit it state "100W+100W"

from datasheet STK 4141

STK4141 X = Rated 75W
STK4141 V = Rated 25W

I'm sure about this info,
but i want to know the nowdays trend, most hifi, audio system and a home theatre today, they are using still using STK or Just a pair of transistor for each channel ?? any one here has the info??

[IndAudio]

Originally Posted by Hakimi

STK4141 X = Rated 75W
STK4141 V = Rated 25W

Sorry, but even STK4141 X is rated at 25W/ch, I think one gets confused by looking at the Data sheet for STK4141 X "series" datasheet where they mention about all the chips in that series like STK4141X, STK4151X...STK4191 then STK4201X, STK4211X in a single data sheet.
STK4211X is rated at 70W/ch.

STK4141 X can deliver 70 W/ch at a very high distortion rate but would need a heavy heat sink and supply upto the max rated supply inputs.

I am aware STK chips were used by Sony, Akai, Panasonic, Aiwa etc for their component systems heavily several years ago, but I am myself interested to know what they are using these days in component systems

[IndAudio]

Originally Posted by Hakimi

but i want to know the nowdays trend, most hifi, audio system and a home theatre today, they are using still using STK or Just a pair of transistor for each channel ?? any one here has the info??

Your post forced me to do a lot of research on sony audio equipment especially as my own interest was also involved here. Here are some of the results.

For its famous Hi-Fi component systems (MHC series) Sony still uses STK series chips like STK411-XXX, STK433-XXX.

For seperates/Home Theater systems it uses transistor based power amps usually driven by a IC based driver for eg MN2488+MP1620 driven by UPC2581 etc..

I hope this give you some insight into what is being used these days by Sony etc

[Hakimi]

IndAudio, Thanks for the info.

actually this information is for my project. the project using recycled hi-fi casing.(all contents removed). there, i will integrate iPod Docking, FM radio, and USB mp3 modulator(some mod) and AUX input. after that the system goes to pre amplifier(bass/tre/vol) by National Semi- LM1036N and now i'm choosing the suitable power amplifier either using transistor or STK which is simple choice that available easily by hobby kits..

[IndAudio]

All the best for your project, publish a few pics once you complete it.

Originally Posted by Hakimi

IndAudio, Thanks for the info.

now i'm choosing the suitable power amplifier either using transistor or STK which is simple choice that available easily by hobby kits..

You could use STK4141 kit if it is readily available. But here are a few words of caution :
1. Make sure you are getting genuine and not a fake STK (google for STK fakes and you will know how to make out the difference).
2. The PCB should be of good quality with proper layout, often people blame STK for failures on the PCB side. I am not an expert on PCB's so not much I can say apart from this.
3. Go through the data-sheet for STK4141 (make sure you get the datasheet for appropriate mark like II, V, X).

However if you want to use the KTB688+KTD718 transistor's then others need to advice you. I have worked with transistors only once, though I liked the sound quality very much (I used 2955+3055 pair), I dropped the idea of using any other for space and heat-sinking requirements, I think my circuit was poorly designed and hence dissipated a lot of heat!!

Muid

[pacificblue]

When mass manufacturers decide on an amplifier technology they usually start by defining the specifications the amplifier has to comply with. Then they check how to meet those requirements in the most economical way. At low output power the chip amp (like LM3886 or TDA7293) or hybrid amp (like the STK series) is usually the choice. The higher the output power the more likely is it that a discrete amplifier costs less money to develop and build.
We are now starting to see a transition to class D (often wrongly called digital), because that technlogy becomes easier to master all the time and its space, heatsinking and power supply requirement advantages tend to outweigh the additional engineering effort.

Whether a chip or hybrid amp sounds better than a transistor amp depends on how good a design you use. A chip or hybrid amp is easier to get right. For a computer sound system it is the more logical choice. If you look e. g. inside of Logitech products, you will always find chip amps doing the job.

[pacificblue]

Originally Posted by IndAudio

I dropped the idea of using any other for space and heat-sinking requirements, I think my circuit was poorly designed and hence dissipated a lot of heat!!

Or maybe it was not poorly designed but class A. The heat dissipation for a given output power is the same and from a certain power upward the lower thermal resistance of several transistors compared to a chip amp rather leads to smaller heatsinks.