Re: TA 2022
Chris,
on this version of the TA2022 amplifier which you have, if the power supply is lower than 27-30V DC, the inductor from the negative supply will make a little noise, because mechanical resonance of the windings and the core, when is working in burst mode. the solution is simple, remove those 2 capacitors which are in front of the rectifier bridge, the 0.22uF at 63V. this are connected between + to GND and - to GND. there are hi-freq by-pass capacitors, but there are few more bypass caps, so this will not have any negative influence. please check and let me know. be carefull which capacitors you remove, if you remove others, may damage the board. ony the 2 caps very close to the rectifier bridge !!!
note that this noise has no negative influence in normal operation of the a amplifier, but it may be annoying if you stick the ear on the board. similar as many SMPS have this noise but they working just fine.
i post the schematic, it is the same for all the boards with single differential voltage, only the value of the caps is different.
i check the 22,000 uF at 50V caps, there is no cap with this value which can fit on this board. they are big can type, with screw terminal only. an alternative will be to use the 18,000uF at 71V which fit exactly on this boards, they are 35mm diameter and 100mm long. the total capacitance is enough even for class A amplifiers.
the biggest capacitance caps which can fit on this board are 12,000uF, the model which i use for the TA3020 v2 board. they are 30mmx50mm. for bigger capacitance, may connect in paralel with this caps, next to the board. one good solution will be to use one 18,000uF at 71V connected between V+ and V- this will increase performance, and attenuate pumping effect which ocures at class D and T amplifiers.
mtbboyz said:
Chris,
on this version of the TA2022 amplifier which you have, if the power supply is lower than 27-30V DC, the inductor from the negative supply will make a little noise, because mechanical resonance of the windings and the core, when is working in burst mode. the solution is simple, remove those 2 capacitors which are in front of the rectifier bridge, the 0.22uF at 63V. this are connected between + to GND and - to GND. there are hi-freq by-pass capacitors, but there are few more bypass caps, so this will not have any negative influence. please check and let me know. be carefull which capacitors you remove, if you remove others, may damage the board. ony the 2 caps very close to the rectifier bridge !!!
note that this noise has no negative influence in normal operation of the a amplifier, but it may be annoying if you stick the ear on the board. similar as many SMPS have this noise but they working just fine.
ccschua said:
i post the schematic, it is the same for all the boards with single differential voltage, only the value of the caps is different.
i check the 22,000 uF at 50V caps, there is no cap with this value which can fit on this board. they are big can type, with screw terminal only. an alternative will be to use the 18,000uF at 71V which fit exactly on this boards, they are 35mm diameter and 100mm long. the total capacitance is enough even for class A amplifiers.
hoxuanduc said:
the biggest capacitance caps which can fit on this board are 12,000uF, the model which i use for the TA3020 v2 board. they are 30mmx50mm. for bigger capacitance, may connect in paralel with this caps, next to the board. one good solution will be to use one 18,000uF at 71V connected between V+ and V- this will increase performance, and attenuate pumping effect which ocures at class D and T amplifiers.
Attachments
Hi CNX
I received the 2 TDA8920TH kits last tuesday. Thank you for your good service.
As a beginner I still have some design questions.
- In the specs you mention I still need an input stage. Googling I still cannot find what exactly that is I need. Can you point me out how I can make an input stage.
- Power supply. Each kit needs a power supply 2x20Vac 6A
is it possible to power the 2 kits with one transformer. (kits in parallel)
Would this be a good idea? http://www.amplimo.nl/index.php?pag...d=12&option=com_virtuemart&Itemid=134&lang=nl
Or would a smps be a better choice?
Are there some books you use with amplifier info?
Thank you
Wim
I received the 2 TDA8920TH kits last tuesday. Thank you for your good service.
As a beginner I still have some design questions.
- In the specs you mention I still need an input stage. Googling I still cannot find what exactly that is I need. Can you point me out how I can make an input stage.
- Power supply. Each kit needs a power supply 2x20Vac 6A
is it possible to power the 2 kits with one transformer. (kits in parallel)
Would this be a good idea? http://www.amplimo.nl/index.php?pag...d=12&option=com_virtuemart&Itemid=134&lang=nl
Or would a smps be a better choice?
Are there some books you use with amplifier info?
Thank you
Wim
ccschua said:
i measured the 18,000uF at 71V caps ESR, they have about 5 mOhm. this is a very low value, not too many caps have ESR so low. the capacitors life is depending on the ripple current and working temperature. the minimum operating life is 4000 hours at 85*C and maximum ripple current. the operating life rise exponentially if the temperature or ripple current decrease, so values of 100,000 hours or more are very common.
the diodes are made by ON Semi.
Attachments
wimpos said:
the input stage is necessary because the TDA892x amplifiers have fixed gain, and in some cases the input level provided by some audio sources may not be enough. depending on your application, the preamplifier can be chosen. if you want to use with CD/DVD, this may provide enough level, but other audio sources may need a simple one-two stages preamplifier.
you can use a single transformer to power two modules, if the transformer has enough power rating (at least 350W). also, is higly recommended that the transformer to have 2 symetrical windings, and use them separate for each amplifier, as you have 2 transformers. the transformers from the link which you post may be a good choice, but i didn't saw 2x20V model. a better choice will be to use 2 transformers like this: http://www.amplimo.nl/index.php?pag...id=9&option=com_virtuemart&Itemid=134&lang=nl
aout SMPS, also can be used, i have a model which fit for this amlplifiers, i hope that this month i will be able to release already.
Re: TDA8924TH
the price for the TDA8920/8924 amplifier Power Supply will be about 70 USD. they will be available this month.
TDA8924TH works well with 4Ohm load in BTL mode, with the mention that the heatsink should be big enough to dissipate the extra heat. also the power supply should be able to deliver at least 250W continuous and 350W peak power.
if you need more power than the TDA8924 amplifier can provide, you can use TA3020 amplifier, or DA-1 amplifier, which is suitable for subwoofer, there is plenty of power for most of the applications.
romtom said:
the price for the TDA8920/8924 amplifier Power Supply will be about 70 USD. they will be available this month.
ohmslaw said:
TDA8924TH works well with 4Ohm load in BTL mode, with the mention that the heatsink should be big enough to dissipate the extra heat. also the power supply should be able to deliver at least 250W continuous and 350W peak power.
if you need more power than the TDA8924 amplifier can provide, you can use TA3020 amplifier, or DA-1 amplifier, which is suitable for subwoofer, there is plenty of power for most of the applications.
Re: DA-1
DA-1 is still available. this amplifier is more suitable for subwoofer applications, but can be used for full range as well. doesn't have low-pass filter on board.
please login on the site and follow the order process, the shipping cost will be calculated automatically and you will be redirected onto paypal site for payment. ussually i make the shipping with HK post, but on request i can use other shipping companies.
a double 47K logarithmic potentiomenter is a good choice for TA3020, since it's input impedance is this value. make sure that is a good quality one, otherwise can create click/pop noise when turning the volume.
norazmi said:
DA-1 is still available. this amplifier is more suitable for subwoofer applications, but can be used for full range as well. doesn't have low-pass filter on board.
please login on the site and follow the order process, the shipping cost will be calculated automatically and you will be redirected onto paypal site for payment. ussually i make the shipping with HK post, but on request i can use other shipping companies.
milachica said:
a double 47K logarithmic potentiomenter is a good choice for TA3020, since it's input impedance is this value. make sure that is a good quality one, otherwise can create click/pop noise when turning the volume.
Re: TDA8924TH
the amplifier inputs are 180* shifted, so one channel is inverted, one non-inverted. by connecting together the inputs, the output signal will be already shifted with 180* and can connect in BTL mode. the main advantage beside the easier bridging is cancelling the pumping effect, which occure at all class and T amplifiers.
so, to work in BTL mode, just connect together the inputs and connect the load between outputs.
ohmslaw said:
the amplifier inputs are 180* shifted, so one channel is inverted, one non-inverted. by connecting together the inputs, the output signal will be already shifted with 180* and can connect in BTL mode. the main advantage beside the easier bridging is cancelling the pumping effect, which occure at all class and T amplifiers.
so, to work in BTL mode, just connect together the inputs and connect the load between outputs.
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