Then it's burnt open.
Measure all 4 to check whether they are still alive.
Replace as needeed
Small value power resistors used in series with output transistors.
Obviously the earlier STK killed 1 or more of them.
Try to follow the recommended schematic.
Well, maybe it's enough, but you'll definitely kill that speaker real fast.
As in minutes.
Do you have a 200/250W speaker?
I mean *real* watts, as specified in a guitar/bass/PA speaker, not "PMPO" , "Car Watts", "program power", etc.
ok, the both the sub and the original speaker are working (tested with my little hi-fi amplifier) but i think that the cone is too small and will suffer (as you told me).
I measured the resistor and is about 22k and more. Maybe it's broken. so I removed it and I ordered a new one.
Unfortunately my solder died, not sure why, maybe the temperature sensor is faulty. I gave it to a friend of mine that can check what's wrong.
Grrrrr, this thing is getting harder and bigger day by day.
I measured the resistor and is about 22k and more. Maybe it's broken. so I removed it and I ordered a new one.
Unfortunately my solder died, not sure why, maybe the temperature sensor is faulty. I gave it to a friend of mine that can check what's wrong.
Grrrrr, this thing is getting harder and bigger day by day.
Good news everyone! (Good News Everyone! - YouTube)
Today I went to the electronics shop to buy the pieces I was missing.
So I bought the new 0.22 ohm 5W resistor, a 1uF 100V capacitor and two 10uF 100V capacitor.
Back home I finished to tin each track (after obviously scraped off the awful green thing on top) and also I add few point to point wires, for example for main supply, main out and so on.
After that I added the new components (the PCB had the right holes and tracks for them! (a part for one ))
With few sweat drops I soldered the 4048V to the pcb.
I re-assembled the amplifier with a big sub-woofer cone just to try it.
I added also a 60W light bulb in series with the main supply, as you told me. The result is in this video. The amplifier seems to works, I can hear some music, the pot can increase and decrease the volume, nothing burned, nothing it's hot, no smoke, no booms.
Here the video: video-2013-03-06-23-48-26 - YouTube
You can't hear any music because the cell can't play music and record videos at the same time.
The thing I am worried about is that flash that the light bulb have when powering the amp. Is that correct? Is correct that the light bulb remains a little glowing when the amp is on?
Any suggestion? How can I be sure the amp is OK, not to burn the new cone I will buy?
I measured the dc voltage at output and is about 15mV (0.015) and the ac voltage change with the volume (obviously).
I found a "ciare" 12' cone ad about 120€ that is 300W woofer, what do you think about it?
Today I went to the electronics shop to buy the pieces I was missing.
So I bought the new 0.22 ohm 5W resistor, a 1uF 100V capacitor and two 10uF 100V capacitor.
Back home I finished to tin each track (after obviously scraped off the awful green thing on top) and also I add few point to point wires, for example for main supply, main out and so on.
After that I added the new components (the PCB had the right holes and tracks for them! (a part for one ))
With few sweat drops I soldered the 4048V to the pcb.
I re-assembled the amplifier with a big sub-woofer cone just to try it.
I added also a 60W light bulb in series with the main supply, as you told me. The result is in this video. The amplifier seems to works, I can hear some music, the pot can increase and decrease the volume, nothing burned, nothing it's hot, no smoke, no booms.
Here the video: video-2013-03-06-23-48-26 - YouTube
You can't hear any music because the cell can't play music and record videos at the same time.
The thing I am worried about is that flash that the light bulb have when powering the amp. Is that correct? Is correct that the light bulb remains a little glowing when the amp is on?
Any suggestion? How can I be sure the amp is OK, not to burn the new cone I will buy?
I measured the dc voltage at output and is about 15mV (0.015) and the ac voltage change with the volume (obviously).
I found a "ciare" 12' cone ad about 120€ that is 300W woofer, what do you think about it?
The flash from the bulb tester at amplifier power on is OK . Just a little glow when the amplifier is running is no problem also. For protection from Dc voltage on the otput of your amplfier you could couple the speaker to it with an electrolytic capacitor say 4700uF 63Vdc. This will allow the ac music signal to pass and block any dc if the amplifier gets faulty again...
If you use a capacitor of a lower value it will affect the bass response .. If any volume reduction it will be very very small. For a high end hifi amplifier there may be a small amount of distortion . for stage monitor use i very much doubt you will notice any change to the audio quality.. Note attach the + side of the cap to the amplifier
A pizo tweeter should always have a series resistor fitted .. piezo tweeters are frequency dependant.. The higher the frequency the lower its impedance will become . this is the reason they need no high pass filter. At high frequencys the tweeter will present the amplifier with a very low impedance.. putting the amplifier or tweeter at risk of overload.. If you make the series resistor say 8 ohm then the tweeter can never present a load of less than 8 ohm to the amplfier. there is no need to low pass the woofer. Get the thing working and then you can learn about filters and why they are used ..
1) the lamp blink at the beginning is normal, for a second the supply capacitors are charging
2) the slight orange glow afterwards is normal, the amplifier "eats" something even without music
3) your amp is split supply, it does NOT use or need an electrolytic capacitor between the outout and the speaker.
The whole point of making symmetrical supply amplifiers is *avoiding* output capacitors.
No, repeat no real world amplifier uses them, yet it's a superstitious belief here at DIY that you need them.
4) *if* you are unduly worried about DC at the speaker, search and build a DCV speaker protection circuit.
99% of them use a relay to disconnect output, 1% uses a Triac to short output to ground.
5) 15 mV DC, in fact anything below 100mV DC at the output is irrelevant.
6) if your +/- rails are around 60 V DC, you *need* a 200W or more speaker.
That Ciare may be fine, it's a respected Pro brand.
I thought you had said that since you are into servicing you had more speakers available.
That little Eminence, which looks like something pulled from an old Acoustic amplifier will not do.
*If* you still want to monitor your piano, you'll need some highs.
*At least* 2 piezos, in parallel with the Ciare but with a 47 ohms 2 to 5W resistor in series with them.
Meaning:
All 3 (-) terminals joined together.
The amplifier output goes straight to the woofer (+) terminal, then trough the resistor to the (+) terminals of the tweeters, joined together.
7) will you mount this into the speaker cabinet or into a separate chassis?
Good luck.
2) the slight orange glow afterwards is normal, the amplifier "eats" something even without music
3) your amp is split supply, it does NOT use or need an electrolytic capacitor between the outout and the speaker.
The whole point of making symmetrical supply amplifiers is *avoiding* output capacitors.
No, repeat no real world amplifier uses them, yet it's a superstitious belief here at DIY that you need them.
4) *if* you are unduly worried about DC at the speaker, search and build a DCV speaker protection circuit.
99% of them use a relay to disconnect output, 1% uses a Triac to short output to ground.
5) 15 mV DC, in fact anything below 100mV DC at the output is irrelevant.
6) if your +/- rails are around 60 V DC, you *need* a 200W or more speaker.
That Ciare may be fine, it's a respected Pro brand.
I thought you had said that since you are into servicing you had more speakers available.
That little Eminence, which looks like something pulled from an old Acoustic amplifier will not do.
*If* you still want to monitor your piano, you'll need some highs.
*At least* 2 piezos, in parallel with the Ciare but with a 47 ohms 2 to 5W resistor in series with them.
Meaning:
All 3 (-) terminals joined together.
The amplifier output goes straight to the woofer (+) terminal, then trough the resistor to the (+) terminals of the tweeters, joined together.
7) will you mount this into the speaker cabinet or into a separate chassis?
Good luck.
Fahey grow up . the guy does not know exactly what he is doing . the cap i mentioned was to protect his speaker while testing ... why do you repeat what others have said only a few lines before ... Is this because i put you on the line ... we are still wating for proof. A cheap cost effective capacitor will do the job as this amplifier will not last long at that supply voltage it will more than likley go dc and wipe out his speaker ...
"Grow up"?
Even more???
What will protect his speaker is measuring that DC is not present, period.
An unneeded electrolytic capacitor will *guaranteed* explode as soon as it receives 3V RMS audio .... which is AC.
As of using that chip amp with less DC voltage, is what I have been telling him from day 1.
Even more???
What will protect his speaker is measuring that DC is not present, period.
An unneeded electrolytic capacitor will *guaranteed* explode as soon as it receives 3V RMS audio .... which is AC.
As of using that chip amp with less DC voltage, is what I have been telling him from day 1.
No the meaurment will only prove if there is dc present at the time of testing for it .. Double period.. And what is this rubbish about the capacitor exploding . so a 4700uF 63vdc capacitor will explode with only 3V RMS Audio. would you bee kind enuff to set up a demo of this and video it please..
No squabbling folks.
If gianmarco wants to add an output capacitor (and that's maybe no bad thing until the amp is proved reliable) then it needs to be non polarised. Easiest way is to use two identical caps wired in series and connected back to back (either + to + or - to -) and of around 6800uf each. Something like a 100K (any high value resistor as long as they are equal) wired across each cap will equalise any DC voltage present.
bad news everyone!
Today I tried the amp.
First try, higher volume, with the light bulb, all was OK, here is the video:
video-2013-03-07-12-39-46 - YouTube
Then I turned off the amp, waiting to the music to gently fade out (about 5 seconds).
I removed the light bulb, turned on, and PUFF, two fuse gone (rated 10A). Immediately I turned off the power, connected the light bulb, and now the result is This (video):
video-2013-03-07-12-51-11 - YouTube
to be Honest I don't know what can be happened. I tried few times to power on and power off the amp with the bulbs and it goes well, the volume was 0 , all precautions taken.... seriously, what the hell can be happened?
Today I tried the amp.
First try, higher volume, with the light bulb, all was OK, here is the video:
video-2013-03-07-12-39-46 - YouTube
Then I turned off the amp, waiting to the music to gently fade out (about 5 seconds).
I removed the light bulb, turned on, and PUFF, two fuse gone (rated 10A). Immediately I turned off the power, connected the light bulb, and now the result is This (video):
video-2013-03-07-12-51-11 - YouTube
to be Honest I don't know what can be happened. I tried few times to power on and power off the amp with the bulbs and it goes well, the volume was 0 , all precautions taken.... seriously, what the hell can be happened?
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