After a few day of searching for the best sounding amplifier on diyAudio.com. I've found that bridging the STK4048XI gives probably the best sound.
Now I want to make my own bridged STK amplifier but I can't find a schematic for the bridged configuration. I know there is an schematic in the datasheet but not for bridging.
When you bridge an stk amplifier the distortion will be lower <0.008 procent over the whole bandwith 20Hz to 20kHz and the signal to noise ration will also be better. I know you need two STK modules/channel, one as inverted and the other as non inverting amplifier. Can anyone help me with a schematic or a description so I can make my own PCB.
Now I want to make my own bridged STK amplifier but I can't find a schematic for the bridged configuration. I know there is an schematic in the datasheet but not for bridging.
When you bridge an stk amplifier the distortion will be lower <0.008 procent over the whole bandwith 20Hz to 20kHz and the signal to noise ration will also be better. I know you need two STK modules/channel, one as inverted and the other as non inverting amplifier. Can anyone help me with a schematic or a description so I can make my own PCB.
One resistor to bridge any amplifier!!!!!
Hi
This is the simplest way to bridge any amplifier in electronics
world ever.Look to the drawing.I really advise you to use this configuration,because I used it with my STK4191II,and its working really fine...I was shocked when it worked,the sound was amazing,I have just obtained 160 watt from one STK4191II to 8 Ohm speaker.....
By connecting the output of one amplifier (First STK4048XI) to the feedback point in the other (Second STK4048XI), using a resistance equal to that for the feedback resistor, the second amp will have a signal gain of unity, and will be inverted, since the feedback is always applied to the inverting input.
BR
Hi
This is the simplest way to bridge any amplifier in electronics
world ever.Look to the drawing.I really advise you to use this configuration,because I used it with my STK4191II,and its working really fine...I was shocked when it worked,the sound was amazing,I have just obtained 160 watt from one STK4191II to 8 Ohm speaker.....
By connecting the output of one amplifier (First STK4048XI) to the feedback point in the other (Second STK4048XI), using a resistance equal to that for the feedback resistor, the second amp will have a signal gain of unity, and will be inverted, since the feedback is always applied to the inverting input.
BR
Attachments
Bridging STK module
Metal:
Thanks for your replay. You wrote:Look to the drawing.I really advise you to use this configuration,
But I can't see a drawing, where is the location of this.
UrSv
Indeed I didn't do a listening test but I base my opinion on the findings and test of people who did. When I read this The STK seems to be very good.
Metal:
Thanks for your replay. You wrote:Look to the drawing.I really advise you to use this configuration,
But I can't see a drawing, where is the location of this.
UrSv
Indeed I didn't do a listening test but I base my opinion on the findings and test of people who did. When I read this The STK seems to be very good.
Bridging Stk module
Hi Metal
Nice schematic but a little strange for me. You have used the names L input and R input. Do you mean left and right input?
I suppose you mean the + and the - of one audio channel.
Also the speaker is connected between the L output and the R output. I think you mean + and - of one channel, because if you connect the speaker between L and R output you will hear only the difference between the left and right channel.
Can you give also some information how you get this schematic. Is it somewhere in a datasheet on the net?
Best regards
kurt
Hi Metal
Nice schematic but a little strange for me. You have used the names L input and R input. Do you mean left and right input?
I suppose you mean the + and the - of one audio channel.
Also the speaker is connected between the L output and the R output. I think you mean + and - of one channel, because if you connect the speaker between L and R output you will hear only the difference between the left and right channel.
Can you give also some information how you get this schematic. Is it somewhere in a datasheet on the net?
Best regards
kurt
A more thorough explaination
Hi Kurt
I have attached another schematic to show you how this is done.
Now,the first opamp symbol denotes the first STK4048XI,and the second opamp symbol denotes the seconed STK4048XI,each opamp symbol has an inverting input (-) that is pin # 2 in the IC,and a non-inverting input (+) that is pin # 1 in the IC.
The bridging is meant to make the first STK4048XI acts as a non-inverting power amplifier,and the seconed STK4048XI as the invetring power amplifier,of course the audio signal is applied only to the first STK4048XI input,while the seconed STK4048XI input is simply connected to ground by a 100 Ohm resistor as shown in the schematic.
To make the simplest bridging ever,you have to add a resistor whose value is equal to the feedback resistor,which is 56KOhm in the datasheet,one terminal of this resistor is connected to the output of the first STK4048XI,of course before the inductor,the seconed terminal is connected to the inverting input pin # 2 in the seconed STK4048XI.
Now,you will take the output from both ICs,the first output is
non-inverted,while the seconed output is inverted.Hence,you will obtain approximately 450 Watts.Enough to make you deaf,but note that the speaker should be 8 Ohm,not less...
If you still have other questions,please don't hesitate to ask,as this is what the forum is all about.
Best Regards
Hi Kurt
I have attached another schematic to show you how this is done.
Now,the first opamp symbol denotes the first STK4048XI,and the second opamp symbol denotes the seconed STK4048XI,each opamp symbol has an inverting input (-) that is pin # 2 in the IC,and a non-inverting input (+) that is pin # 1 in the IC.
The bridging is meant to make the first STK4048XI acts as a non-inverting power amplifier,and the seconed STK4048XI as the invetring power amplifier,of course the audio signal is applied only to the first STK4048XI input,while the seconed STK4048XI input is simply connected to ground by a 100 Ohm resistor as shown in the schematic.
To make the simplest bridging ever,you have to add a resistor whose value is equal to the feedback resistor,which is 56KOhm in the datasheet,one terminal of this resistor is connected to the output of the first STK4048XI,of course before the inductor,the seconed terminal is connected to the inverting input pin # 2 in the seconed STK4048XI.
Now,you will take the output from both ICs,the first output is
non-inverted,while the seconed output is inverted.Hence,you will obtain approximately 450 Watts.Enough to make you deaf,but note that the speaker should be 8 Ohm,not less...
If you still have other questions,please don't hesitate to ask,as this is what the forum is all about.
Best Regards
Attachments
Looking for the best sounding schematic.
Metal, Tanks for a nice drawing schematic but......
I've read something more about bridging amplifiers. So your schematic works but it is not a good amplifier because you have used the output of the first amp as the input for the second amp.
In this way you increase the distortion. The distortion at the output of the first amp is connected with the input of the second amp, so the output of the second amp will have a distortion twice (X2).
In the application note from National I've found a better schematic. Follow this link:
Bridging
When you look to the schematic on page 5 there is less distortion because the input is not an output of an orther amp. The first amp is used as non inverting and the second as inverting amp.
In the datasheet from the LM4780 on page 19 I found that a inverting amp has less distortion as a non inverting amp.
What do you suggest? I think this is a better schematic. The difficulty is to calculate the values of the resisters for the STK4148.
Best regards
Kurt (let the projects goo...)
Metal, Tanks for a nice drawing schematic but......
I've read something more about bridging amplifiers. So your schematic works but it is not a good amplifier because you have used the output of the first amp as the input for the second amp.
In this way you increase the distortion. The distortion at the output of the first amp is connected with the input of the second amp, so the output of the second amp will have a distortion twice (X2).
In the application note from National I've found a better schematic. Follow this link:
Bridging
When you look to the schematic on page 5 there is less distortion because the input is not an output of an orther amp. The first amp is used as non inverting and the second as inverting amp.
In the datasheet from the LM4780 on page 19 I found that a inverting amp has less distortion as a non inverting amp.
What do you suggest? I think this is a better schematic. The difficulty is to calculate the values of the resisters for the STK4148.
Best regards
Kurt (let the projects goo...)
link
My link didn't came through in the previous here it is:
http://www.national.com/an/AN/AN-20.pdf
My link didn't came through in the previous here it is:
http://www.national.com/an/AN/AN-20.pdf
Resistor Values Mr.Kurt,with a better solution
Hi Kurt
I took this part of electronics in the university on my seconed year,now I'm in the fourth,so you have to rock your mind with me a little bit,ok.
I have attached a new schematic,in order to show you how this is done,mathematics follow,ok.
The non-inverting amplifier shown in the datasheet of the STK4048XI has a closed-loop gain given as :
Gain=(56 KOhm/560 Ohm)+1=101
In order to obtain the same closed-loop gain for the inverting configuration of the seconed STK4048XI,after altering the values by adding a 560 Ohm resistor in series with the 56 KOhm for the inverting STK4048XI,the gain becomes :
Gain=((56 KOhm+560 Ohm)/560 Ohm)=101
In the accompanying schematic 1,input impedance of the seconed STK4048XI is very low compared to the first STK4048XI,this has the advantage of extended chest pounding bass response,and all the disadvantages of low input impedance.
You have to choose the input capacitors in order to maintain the same response for both amplifiers,that is 4.7 uf for the first STK4048XI,and 22 uf for the second STK4048XI.
NOW,NOW.NOW.READ THIS..............
I DON'T ADVISE THIS CONFIGURATION,Because there are many disadvantages result from this configuration,such as low input impedance of the seconed STK4048XI,etc.
Look to the seoned schematic 2,which is much better than reconfiguring the STK's,the inversion purpose is accomplished in the seconed opamp,here you can see that the input impedance that the audio signal source sees is simply 100 KOhm.
Its up to you which schematic you can use,you also can change the resistor values in the first schematic,but if I were you,I would use the seconed schematic.
Bye
Hi Kurt
I took this part of electronics in the university on my seconed year,now I'm in the fourth,so you have to rock your mind with me a little bit,ok.
I have attached a new schematic,in order to show you how this is done,mathematics follow,ok.
The non-inverting amplifier shown in the datasheet of the STK4048XI has a closed-loop gain given as :
Gain=(56 KOhm/560 Ohm)+1=101
In order to obtain the same closed-loop gain for the inverting configuration of the seconed STK4048XI,after altering the values by adding a 560 Ohm resistor in series with the 56 KOhm for the inverting STK4048XI,the gain becomes :
Gain=((56 KOhm+560 Ohm)/560 Ohm)=101
In the accompanying schematic 1,input impedance of the seconed STK4048XI is very low compared to the first STK4048XI,this has the advantage of extended chest pounding bass response,and all the disadvantages of low input impedance.
You have to choose the input capacitors in order to maintain the same response for both amplifiers,that is 4.7 uf for the first STK4048XI,and 22 uf for the second STK4048XI.
NOW,NOW.NOW.READ THIS..............
I DON'T ADVISE THIS CONFIGURATION,Because there are many disadvantages result from this configuration,such as low input impedance of the seconed STK4048XI,etc.
Look to the seoned schematic 2,which is much better than reconfiguring the STK's,the inversion purpose is accomplished in the seconed opamp,here you can see that the input impedance that the audio signal source sees is simply 100 KOhm.
Its up to you which schematic you can use,you also can change the resistor values in the first schematic,but if I were you,I would use the seconed schematic.
Bye
Attachments
Waw great job
Hi Metal,
Indeed the inverting amp has a lower input impedance so you need a bigger cap. This gives nonlinearity in frequentie respons.
So, if i understand your solution is to put schematic 2 before schematic 1. (correct me if i am wrong).
When you do this you have the advantage of high input inpedance but you have the additional distortion of the TL072.
On the AN-1192 from National this is done by U7 on page 13.
There is only one opamp used.
When we will use 2 non-inverting STK modules the solution is the best I think. But we don't know the distortion of TL072.
It's a very interesting schematic. Did you already saw an amplifier based on this configuration?
Best regards
Kurt
Hi Metal,
Indeed the inverting amp has a lower input impedance so you need a bigger cap. This gives nonlinearity in frequentie respons.
So, if i understand your solution is to put schematic 2 before schematic 1. (correct me if i am wrong).
When you do this you have the advantage of high input inpedance but you have the additional distortion of the TL072.
On the AN-1192 from National this is done by U7 on page 13.
There is only one opamp used.
When we will use 2 non-inverting STK modules the solution is the best I think. But we don't know the distortion of TL072.
It's a very interesting schematic. Did you already saw an amplifier based on this configuration?
Best regards
Kurt
No,Correction
Hi Kurt
I have seen the application note and this has nothing to do with servo's or any thing that I was talking about,any way I meant by circuit 2,is to build both STK4048XI as non-inverting power amplifiers,as shown in the datasheet,then using the seconed circuit in the schematic to feed the signal to the STK's .
Please look carefully to the seconed circuit,the TL072-A is configured as a buffer,while the TL072-B is an inverting one,this can be used as follows :
The output of the first opamp TL072-A is fed to the first STK4048XI input.And the output of the seconed opamp TL0720-B is fed to the seconed STK4048XI input.
This will relief you from redesigning the inverted form of the STK4048XI circuit,also kills non-linearity,which has more danger than saying,,,ohhhh,the TL072-B opamp distortion is added to my 0.008% STK4048XI THD performance,OK.
Please read what Douglas Self has said about the non-linearity in power amplifiers.
BR
Hi Kurt
I have seen the application note and this has nothing to do with servo's or any thing that I was talking about,any way I meant by circuit 2,is to build both STK4048XI as non-inverting power amplifiers,as shown in the datasheet,then using the seconed circuit in the schematic to feed the signal to the STK's .
Please look carefully to the seconed circuit,the TL072-A is configured as a buffer,while the TL072-B is an inverting one,this can be used as follows :
The output of the first opamp TL072-A is fed to the first STK4048XI input.And the output of the seconed opamp TL0720-B is fed to the seconed STK4048XI input.
This will relief you from redesigning the inverted form of the STK4048XI circuit,also kills non-linearity,which has more danger than saying,,,ohhhh,the TL072-B opamp distortion is added to my 0.008% STK4048XI THD performance,OK.
Please read what Douglas Self has said about the non-linearity in power amplifiers.
BR
Kurt said:
i dont think sofirst of all bridging is done to increase power - not to improve sound
did u try bridging LM chips ? i think they are much better then STKs
anyway
if u got to already finished amps , to bridge them all u need to do is to add an inverting op amp to one of the amps input
if u r going to build a bridged amp then i think u should make one amp with inverting and the other with noninverting input .
TL072 OPAMP
Hi again
As you said above,circuit 2 is used before the STK's,but both STK's are built as shown in the datasheets.A non-inverting modules,no play or modification on the circuit in the datasheets is reqyired.
The TL072 is a very low distortion opamp,please follow this link,and read the datasheet carefully.
focus.ti.com/lit/ds/symlink/tl072.pdf
BR
Hi again
As you said above,circuit 2 is used before the STK's,but both STK's are built as shown in the datasheets.A non-inverting modules,no play or modification on the circuit in the datasheets is reqyired.
The TL072 is a very low distortion opamp,please follow this link,and read the datasheet carefully.
focus.ti.com/lit/ds/symlink/tl072.pdf
BR
Why two OPAMPs???!!!
Hi All
I used two opamps to maintain the same audio signal delay for both non-inverting STK4048XI ICs.
If it happened and I used one inverting opamp for the seconed STK4048XI,then I have a delayed output at the seconed STK4048XI,everybody,try to figure out what I am saying,this will give some phase delay and a seriousely ditorted output,instead of just increased output power and much higher than 0.008% THD.
BR
Hi All
I used two opamps to maintain the same audio signal delay for both non-inverting STK4048XI ICs.
If it happened and I used one inverting opamp for the seconed STK4048XI,then I have a delayed output at the seconed STK4048XI,everybody,try to figure out what I am saying,this will give some phase delay and a seriousely ditorted output,instead of just increased output power and much higher than 0.008% THD.
BR
Good job
Hi Metal,
I understand the schematic completely.
I just ignore the servo's, but the only thing I wanted to mention was the function of U7 in the application note. This is the inverting amp at the beginning of the schematic, it has the same function as the TL072. (correct me if I'am wrong)
You even keep track with the sound delay that is the reason of the 2 TL072. I didn't thought about this. But you are right. We can make two exactly the same STK4048 amps. The noise and distortion of the TL072 will be very low hopefully <0.001.
I will look if there is a simular schematic somewhere then we can compere. (resistor values etc)
SSS:
You posted:
Increase power is the most common use, but when you look in the application note AN1192 (see link above) you see that the distortion in the bridged configuration is much lower, there is a higher degree of linearity and sound will be cleaner. The voltage swing at the speaker is doubled so the slewrate (V/micro second) will be doubled.
Best regards
Kurt
Hi Metal,
I understand the schematic completely.
When I was talking about AN-1192.
I just ignore the servo's, but the only thing I wanted to mention was the function of U7 in the application note. This is the inverting amp at the beginning of the schematic, it has the same function as the TL072. (correct me if I'am wrong)
You even keep track with the sound delay that is the reason of the 2 TL072. I didn't thought about this. But you are right. We can make two exactly the same STK4048 amps. The noise and distortion of the TL072 will be very low hopefully <0.001.
I will look if there is a simular schematic somewhere then we can compere. (resistor values etc)
SSS:
You posted:
Increase power is the most common use, but when you look in the application note AN1192 (see link above) you see that the distortion in the bridged configuration is much lower, there is a higher degree of linearity and sound will be cleaner. The voltage swing at the speaker is doubled so the slewrate (V/micro second) will be doubled.
Best regards
Kurt
To SSS
Hi SSS
You Said...........
I say............
Hey,slow down please,I don't think that LM3886 chip is better than STK4048XI,nor easier to install on a veroboard because of its package pin configuration,please note the XI suffix,it is for THD=.008%,this IC gives an RMS output power of 150 watt to 8 Ohm speaker,and it can be easily put on a veroboard.
On the other hand,LM3886,gives38 watt into 8 Ohm,and 68 watt output power to 4 Ohm,and THD=0.1%.
And by the way don't forget that the STK4048XI is a hybrid IC,while the LM3886 is a monolithic IC,so the STK can handle more stringent operating conditions.
Please don't get upset of my reply,as we still neighbors,ok..
BR
Hi SSS
You Said...........
I say............
Hey,slow down please,I don't think that LM3886 chip is better than STK4048XI,nor easier to install on a veroboard because of its package pin configuration,please note the XI suffix,it is for THD=.008%,this IC gives an RMS output power of 150 watt to 8 Ohm speaker,and it can be easily put on a veroboard.
On the other hand,LM3886,gives38 watt into 8 Ohm,and 68 watt output power to 4 Ohm,and THD=0.1%.
And by the way don't forget that the STK4048XI is a hybrid IC,while the LM3886 is a monolithic IC,so the STK can handle more stringent operating conditions.
Please don't get upset of my reply,as we still neighbors,ok..
BR
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.