Hi all,
I actually try to repair an Onkyo TX15 Amp/FM receiver which is based on an STK459 chip amplifier. The STK459 doesn’t work anymore, I found some replacement parts. Surprisingly, some online resellers seem to have some STK459 in shop for approx. 25-30€.
Since I’m repairing that amp more for fun and challenge than something else, I was thinking about using another power amp which may have some better characteristics than this more than 10-years old IC.
What in your mind could be a replacement IC that would provide a better sound than the STK459 ?
Thanks in advance,
I actually try to repair an Onkyo TX15 Amp/FM receiver which is based on an STK459 chip amplifier. The STK459 doesn’t work anymore, I found some replacement parts. Surprisingly, some online resellers seem to have some STK459 in shop for approx. 25-30€.
Since I’m repairing that amp more for fun and challenge than something else, I was thinking about using another power amp which may have some better characteristics than this more than 10-years old IC.
What in your mind could be a replacement IC that would provide a better sound than the STK459 ?
Thanks in advance,
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STK459 is a good one. Don't look from the age, but Sanyo chips have "classes". Unfortunately it is just 15W.
With original power of only 15W, the transformer capacity will also be that small. You can build a new amp to be attached on the old heatsink. Find IC that requires small heatsink and can be fed with the same supply (around +/-21V)
TDA2030 is good but the original power supply will probably be too high (18V is max here).
LM1875 will give around 18W @ 8Ohm-21V. But may be the heatsink will get very hot at full power.
A discrete amplifier with TIP31/32 will be better, if you know how to do it. You will need a breadboard pcb to be attached on the heatsink. Just search the forum for small BJT amplifier. Or may be you can find such amplifier module locally. Here, the cost will be less than $5, with "fake" components.
With original power of only 15W, the transformer capacity will also be that small. You can build a new amp to be attached on the old heatsink. Find IC that requires small heatsink and can be fed with the same supply (around +/-21V)
TDA2030 is good but the original power supply will probably be too high (18V is max here).
LM1875 will give around 18W @ 8Ohm-21V. But may be the heatsink will get very hot at full power.
A discrete amplifier with TIP31/32 will be better, if you know how to do it. You will need a breadboard pcb to be attached on the heatsink. Just search the forum for small BJT amplifier. Or may be you can find such amplifier module locally. Here, the cost will be less than $5, with "fake" components.
BTW, overture series from National is good. LM3875 is rated max 56W, LM4766/LM4765 is rated max 30W. With 21V supply they will give around 20W. Cheaper than the STK.
STK 457, 459, 460, 461, 463 are all pin compatible.
Fake "OEM" STK 465 is also pin compatible but the optimal support circuit is different on the New/current production item, so that's not an exact replacement.
Cheaper modern chips aren't necessarily better, nor more powerful.
What is an STK chip? Its a real discrete solid state amplifier jam packed into a little black box. Nearest match is a discrete amplifier, not a chip.
Want better sound than STK459? STK460 on regulated power. 🙂
When also within a circuit optimized for it, including bass treble controls, I don't think that there's any other chip that an beat it unless you cable bypass all of the controls except for the source selector. In this case, a refit to a modern chip is like vandalism. And, without completely bypassing the tone section, a refit/modernization is pointless since that would only degrade performance, as in screaming mids, weird tone, and probably lots of clipping. Instead of terrible noise and/or cut out features, I'd rather use STK 459/460 or 461/463 for restorations.
Wattage output? In the past, they measured at 0.01% or better figures. Actually if you crank that thing up to modern measuring figures, its puts out more than 15 watts. For production examples, its more like 27w (only 3 decibels less than a 55w amplifier). Some odd 34 years ago, customers bought audio amplifiers by favorable distortion figures and the easiest way to publish such figures is to turn the volume control to about half, then advertising both less wattage and less distortion. Today's practice is the opposite.
Usually, the STK459 was cherry picked for manufacturers, a non-standard model, with better specs and a higher voltage tolerance. Check your power supply voltage!
The six chips in that family have only 2 designs.
457/459/460 for pair of 18 to 24vdc rails
461/463/465 for pair of 24 to 30vdc rails
There are alternatives to restore original performance while also using a modern chip, but, you're looking at a fairly big mess that certainly doesn't cost less than simply using the correct part. 🙂
Fake "OEM" STK 465 is also pin compatible but the optimal support circuit is different on the New/current production item, so that's not an exact replacement.
Cheaper modern chips aren't necessarily better, nor more powerful.
What is an STK chip? Its a real discrete solid state amplifier jam packed into a little black box. Nearest match is a discrete amplifier, not a chip.
Want better sound than STK459? STK460 on regulated power. 🙂
When also within a circuit optimized for it, including bass treble controls, I don't think that there's any other chip that an beat it unless you cable bypass all of the controls except for the source selector. In this case, a refit to a modern chip is like vandalism. And, without completely bypassing the tone section, a refit/modernization is pointless since that would only degrade performance, as in screaming mids, weird tone, and probably lots of clipping. Instead of terrible noise and/or cut out features, I'd rather use STK 459/460 or 461/463 for restorations.
Wattage output? In the past, they measured at 0.01% or better figures. Actually if you crank that thing up to modern measuring figures, its puts out more than 15 watts. For production examples, its more like 27w (only 3 decibels less than a 55w amplifier). Some odd 34 years ago, customers bought audio amplifiers by favorable distortion figures and the easiest way to publish such figures is to turn the volume control to about half, then advertising both less wattage and less distortion. Today's practice is the opposite.
Usually, the STK459 was cherry picked for manufacturers, a non-standard model, with better specs and a higher voltage tolerance. Check your power supply voltage!
The six chips in that family have only 2 designs.
457/459/460 for pair of 18 to 24vdc rails
461/463/465 for pair of 24 to 30vdc rails
There are alternatives to restore original performance while also using a modern chip, but, you're looking at a fairly big mess that certainly doesn't cost less than simply using the correct part. 🙂
hello.
i have an old sanyo dca205 integrated amp, one of my "tweaker's objects".
one channel of the stk461 inside was dead,so i substituted it with the cheaper stk459 (i bought it from a wellknown german electronic seller)........psu volts are a little bit higher than recommended,but it works without problems.
i recapped the amp,all electrolytics were changed to new ones,
and after that the big (cheap) ceramic caps with plastic caps (mkt and so on.).
may say the amp sounds much better than i thought it could be.......
i have an old sanyo dca205 integrated amp, one of my "tweaker's objects".
one channel of the stk461 inside was dead,so i substituted it with the cheaper stk459 (i bought it from a wellknown german electronic seller)........psu volts are a little bit higher than recommended,but it works without problems.
i recapped the amp,all electrolytics were changed to new ones,
and after that the big (cheap) ceramic caps with plastic caps (mkt and so on.).
may say the amp sounds much better than i thought it could be.......
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That is okay if it is running 8 ohm speakers and if the amplifier has mains fuses. Even so, it is running a slight overrun condition and I would expect it to fail, in approximately 40 years. That lifespan would be for a "pull" or a NOS replacement part for an amplifier brand.
However, an STK generic or an authentic part that wasn't the higher spec for big name manufacturers may have a much shorter lifespan.
There are 2 or 3 different STK459. . .
The best of these were made for Technics, or Sony, or some other big name that have higher/better spec because the manufacturer required it and because the part was especially made to the requirements of the amplifier manufacturer. Today it is found as a "pull"
The worst is the current production "OEM" fake STK465 with the label re-printed to STK459 in order to attract a greater amount of customers. Such a re-labeling is typical of generic parts.
In-between the two extremes is the normal grade STK459. This one matches the datasheet. It was sold to hobbyists and parts vendors.
However, an STK generic or an authentic part that wasn't the higher spec for big name manufacturers may have a much shorter lifespan.
There are 2 or 3 different STK459. . .
The best of these were made for Technics, or Sony, or some other big name that have higher/better spec because the manufacturer required it and because the part was especially made to the requirements of the amplifier manufacturer. Today it is found as a "pull"
The worst is the current production "OEM" fake STK465 with the label re-printed to STK459 in order to attract a greater amount of customers. Such a re-labeling is typical of generic parts.
In-between the two extremes is the normal grade STK459. This one matches the datasheet. It was sold to hobbyists and parts vendors.
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i have an old AKAI amplifier with an STK461 chip... the chip is not working anymore and the fuse keeps on blowing out!... dnt know why... and i thought of replacing the chip with STK465. can it be possible?
i just want to repair my old amp and see if i can restore it and maybe perhaps boost its power output by replacing the STK461 to STK465.. thanks for the help!
thanks so much for that info... i have already fixed the "blown fuse" problem". one of the caps is leaked and loosen... haven't yet bought the STK465 but i there are still available. i replaced my 2 6200uf/35v main caps for a 10,000uf/65v caps. are that ok? hoping to give out a more steady charge into the chip.
btw, my main transformer gives out a 23+/-vac. should i change that with a bigger transformer(say, 30+/-vac)and change all the caps in the circuit with the same voltage rate, would that be ok? thanks ahead.
hi Daniel, are you familiar with stk432-050 ? do you know the pin arrangement? better yet a schematic for amplifier for this chip. thanks.
hi daniel, aside from the STK465 that i can replace with my STK461, are there still any other pin compatible with the STK461? i wonder what if the chip of the akai am2850 can be pin compatible with the STK461... thanks a lot!
Is there any way of identifying them ?
I came across some power modules from some 3-way active speakers.
They have 2 stks: stk459 & stk 084G
The 459 is for mids and highs ; unfortunately i have no ideea about the manufacturer, but they seem german because there are some frako/roe capacitors on the boards.
this is one of the boards
If I had the serial number database then yes, but otherwise no. However, there's one easy way with that chip. What is the DC operating voltage? If it is a bit high, then suspect a custom chip, like the Technics, Sony, Akai, etc. . . which were ordered in large batches. This is only a concern if you need a replacement chip. . . and then you'll need to pick a pin compatible chip from the same series, and with the right voltage specs.
Here's a summary:
457, 459, 460, 461, 463, 465 STK chip
18 , 21 , 23 , 24 , 26 , 28 VDC per each rail
15w, 20w, 25w, 27w, 30w, 35w RMS power to 8R speaker
For example, the Technics SA80 can be repaired with STK460, 461, 463, 465.
i haven't got around to power them up and measure the supply, but the caps are rated at 35v.
However, i think the power supply for this stk459(one channel drives the mids , the other drives the highs) might be lower as i see some big power resistor in series with the rails.
Do you have any clue as to the origin of these amp boards?(picture in the post before)
However, i think the power supply for this stk459(one channel drives the mids , the other drives the highs) might be lower as i see some big power resistor in series with the rails.
Do you have any clue as to the origin of these amp boards?(picture in the post before)
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Hi, I was looking for a new STK459 to go in a York power amplifier (can't find any info about it but it's Japanese, about 30 years old and a neat little mini system to keep in my room.) One of the channels blew on it while I was running it perhaps a bit hard. I've checked it out, one of the speaker fuses blew but the amp channel still got taken out. Anyway, I'd already decided to recap it before this happened and now want to replace the chip. I've ordered an recycled STK465 as I couldn't find any STK459's for sale in the UK and am fearful of Chinese import fakes. Is this chip going to struggle with the lower voltage (comes out around 23v.)? I don't expect it to outperform the original as the power supply will have always been the limiting factor I guess. I just want it to sound good!
It is best to buy used 457, 459, 460, 461, 463, 465 (because the new production is mostly fakes.)
Lower voltage wouldn't make your chip struggle.
The, 23+23vdc rails isn't too low for STK459 or STK460, or STK461 which is slightly more durable.
Typical of retail builds and a very few smart diy builds, the power supply is rated to provide not more than the chip would handle; but, in this case, it seems that you have a little more than you need.
It might be good to inspect the fuses and see if they're the right value.
Lower voltage wouldn't make your chip struggle.
The, 23+23vdc rails isn't too low for STK459 or STK460, or STK461 which is slightly more durable.
Typical of retail builds and a very few smart diy builds, the power supply is rated to provide not more than the chip would handle; but, in this case, it seems that you have a little more than you need.
It might be good to inspect the fuses and see if they're the right value.
I have already checked the fuses, the chip isn't a new one, it is a refurbished, or at least that's how it was sold on eBay. Looks like it's been on the soldered from another clients, so hopefully it's an original. I suppose there is no real way of telling except for listening, and the system is now up and running. I have to say for a single chip with a few resistors and's caps the sound is excellent!
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