can't remember how or where to check if they are fake, but yes try to change the "sync" resistor, this is how i got the amp to work in the first place, else it sounded like you describe and also at low volume it would be awefull
EDIT: try values from 4 ohm to 30 ohm, if that does now work then try lower.
You could start with a potentiometer AT LOW levels unless you have a 3W or better pot, a 100Ohm pot would do to start with.
EDIT: try values from 4 ohm to 30 ohm, if that does now work then try lower.
You could start with a potentiometer AT LOW levels unless you have a 3W or better pot, a 100Ohm pot would do to start with.
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Hi all. This is my first post here greetings from Finland.
I build pair of these amps and they are awesome. Now i have amp for 18" 2ohm sub driver
. Thanks to Dr frost for shearing. Only difficulties in building prosess was mistake to buy TDA:s from ebay. unbelivible chinese pirate crab. I learn my lesson.
I build pair of these amps and they are awesome. Now i have amp for 18" 2ohm sub driver
. Thanks to Dr frost for shearing. Only difficulties in building prosess was mistake to buy TDA:s from ebay. unbelivible chinese pirate crab. I learn my lesson. 
The output Bias is 0 VDC as there is no Bias to be set. This is a Raw Class B configuration in the original post. Any transistor that can handle the power should be just fine.
For those of you that have facebook and want "faster" help go to https://www.facebook.com/groups/760434413975466
Hi. typical question in this thread
I built it according to this schematic.
I have 300va 2x35vac transformer, 50vdc after rectifing(8xmur860 & 60k of caps)
using 4ohm speaker, what power is to be expected?
I built it according to this schematic.
I have 300va 2x35vac transformer, 50vdc after rectifing(8xmur860 & 60k of caps)
using 4ohm speaker, what power is to be expected?
An externally hosted image should be here but it was not working when we last tested it.
bridged into 4ohms is equivalent to two amplifiers driving 2ohms.
+-50Vdc supplies give about 100W into 8ohms, or 200W into 4ohms, or 400W into 2ohms, if you design the amplifiers to achieve adequate current delivery.
For the bridged arrangement you get double the power into double the impedance.
So your two 400W into 4ohms amplifiers will give 800W into 4ohms, just before you have blown them up.
I have no idea what to predict for lifetime.
+-50Vdc supplies give about 100W into 8ohms, or 200W into 4ohms, or 400W into 2ohms, if you design the amplifiers to achieve adequate current delivery.
For the bridged arrangement you get double the power into double the impedance.
So your two 400W into 4ohms amplifiers will give 800W into 4ohms, just before you have blown them up.
I have no idea what to predict for lifetime.
Thanks AndrewT for clarifying.
Though is that just the about the chips, or with the transistors?
And so the transformer is the limiter, if I'd want more I'd upgrade the power rating?
There came an issue also.
I had it working for a bit, before i mounted it to the radiator, worked fine.
After I mounted it to the radiator (using a piece on steel between the chips and the radiator as a spacer), it worked for maybe 20sec, then just the music stopped. No smoke or nothing. I did use mica insulators on the transistors, but not the tda-s.
what might have gone so wrong?
Though is that just the about the chips, or with the transistors?
And so the transformer is the limiter, if I'd want more I'd upgrade the power rating?
There came an issue also.
I had it working for a bit, before i mounted it to the radiator, worked fine.
After I mounted it to the radiator (using a piece on steel between the chips and the radiator as a spacer), it worked for maybe 20sec, then just the music stopped. No smoke or nothing. I did use mica insulators on the transistors, but not the tda-s.
what might have gone so wrong?
Attachments
![IMAG0453[1].jpg](/community/data/attachments/385/385082-8a6df6e114c6ba98365b958718cd624b.jpg)
Okay.
But why would it be any different, using an insulator or not? should use a plastic bolt of some sort then, for completely isolating the chip.
I would have gone down that route, but using a multimeter on the "beep" mode, it showed that the two tda cases are connected(without the steel piece ofc), removing the need for isolating them.
But why would it be any different, using an insulator or not? should use a plastic bolt of some sort then, for completely isolating the chip.
I would have gone down that route, but using a multimeter on the "beep" mode, it showed that the two tda cases are connected(without the steel piece ofc), removing the need for isolating them.