Output capacitor is 6800 mfd 35 volts.
470mfd is 100volt type,
both with foils in parallel.
Input capacitor 0,47mfd MKP - Amp is for a fullrange driver Beyma 8 agn which will be supported with a 20cm bass driver.
Bass reflex 70 liter box with concrete reinforcement, both drivers with separated current drive amps, 6db low pass for the bass driver.
470mfd is 100volt type,
both with foils in parallel.
Input capacitor 0,47mfd MKP - Amp is for a fullrange driver Beyma 8 agn which will be supported with a 20cm bass driver.
Bass reflex 70 liter box with concrete reinforcement, both drivers with separated current drive amps, 6db low pass for the bass driver.
Attachments
However, I looked up the schematics again an made a new try. This is in analogy of the modification for the STK4241.
STK4132 is not much different.
I will test this as I ordered two amplifiers with STK4132 which are ready assembled.
STK4132 is not much different.
I will test this as I ordered two amplifiers with STK4132 which are ready assembled.
Attachments
For the TDA2003 I found no ready made amplifiers any more anywhere but a look to the TDA2005 helped.
At Aliexpress you get them for 3,6 Euro a stereo amp. At Ebay at the moment for ten euros.
I will try to change them to current drive.
At Aliexpress you get them for 3,6 Euro a stereo amp. At Ebay at the moment for ten euros.
I will try to change them to current drive.
Attachments
Result of listening test with TDA2003 with current drive network showed that it is possible to attach a load less than 4 Ohms. The amplifier works.
But with a power supply of 2.5 Ampere 15 Volt for a stereo pair of TDA2003 the attachment of a loudspeaker driver with 2.6 Ohms showed that distortion goes up again. Maybe the power supply should be made more strong or the output power due to lower impedance is not desireable from a sonic point of view.
A 8 ohm fullrange loudspeaker profits a lot from current drive with TDA2003. Its sound gets more highs and lows and everything sounds more correct.
With two 8 ohms loudspeakers connected everything still fine.
But a third one what gets impedance lower than 4 ohms distortion rises up again.
But with a power supply of 2.5 Ampere 15 Volt for a stereo pair of TDA2003 the attachment of a loudspeaker driver with 2.6 Ohms showed that distortion goes up again. Maybe the power supply should be made more strong or the output power due to lower impedance is not desireable from a sonic point of view.
A 8 ohm fullrange loudspeaker profits a lot from current drive with TDA2003. Its sound gets more highs and lows and everything sounds more correct.
With two 8 ohms loudspeakers connected everything still fine.
But a third one what gets impedance lower than 4 ohms distortion rises up again.
Does anyone have an idea how to realize with a bridged TDA2003 a current drive like Esa Merilainen described on his website (I made a citation in this thread here).
https://www.diyaudio.com/community/...n-to-current-drive.389985/page-7#post-7217389
Citation Esa Merilainen:
Bridging
The concept of bridging, much employed in voltage amplifiers, is also applicable to current-drive systems. Below is shown a bridge-connected transconductor topology, in which one power amplifier (A1) controls the current flowing through the load while an other (A2) mirrors the output voltage of the former to opposite polarity. A3 and resistors labeled R2 make up a difference amplifier that provides a load current dependent feedback signal similarly as above in the grounded load case.
Current output amplifier using bridging
The current taken from the output of A1 can now be 2-fold compared to a corresponding unbridged circuit, and the value of the current-sensing resistor (R1) can be half of that one would use without bridging.
https://www.diyaudio.com/community/...n-to-current-drive.389985/page-7#post-7217389
Citation Esa Merilainen:
Bridging
The concept of bridging, much employed in voltage amplifiers, is also applicable to current-drive systems. Below is shown a bridge-connected transconductor topology, in which one power amplifier (A1) controls the current flowing through the load while an other (A2) mirrors the output voltage of the former to opposite polarity. A3 and resistors labeled R2 make up a difference amplifier that provides a load current dependent feedback signal similarly as above in the grounded load case.
Current output amplifier using bridging
The current taken from the output of A1 can now be 2-fold compared to a corresponding unbridged circuit, and the value of the current-sensing resistor (R1) can be half of that one would use without bridging.
Attachments
I made a proposal for a conversion of TDA2030 which is also widely available as a ready made amplifier board on the markets.
Original schematic from the datasheet and a try for a change to current drive/current feedback.
Maybe someone who knows better than me checks it?
I dropped R2 and changed C2 from 22 mfd to 220 mfd and added the resistor to ground.
Original schematic from the datasheet and a try for a change to current drive/current feedback.
Maybe someone who knows better than me checks it?
I dropped R2 and changed C2 from 22 mfd to 220 mfd and added the resistor to ground.
Attachments
For post 171 in this thread I have to make a correction.
TDA2003 works sonically well with 2 ohm operation.
The loudspeaker had an impedance of 4 ohms - so connection of 3 of them in parallel does not work.
And Sound degradation was due to impedance lower than 1.6 ohms what the TDA2003 can do.
So the TDA2003 is a great little chipamp as it can work with 2 ohm loudspeaker impedance and sounds very well.
TDA2003 works sonically well with 2 ohm operation.
The loudspeaker had an impedance of 4 ohms - so connection of 3 of them in parallel does not work.
And Sound degradation was due to impedance lower than 1.6 ohms what the TDA2003 can do.
So the TDA2003 is a great little chipamp as it can work with 2 ohm loudspeaker impedance and sounds very well.
If I should rank those Chips. Based on my simulations
1. LM1875 It is superior. Has an upper bandwidth of 300kHz in current drive circuit
2. TDA2030 Has an upper bandwidth of 50kHz in current drive circuit
3. TDA2003 Has an upper frequency of 15kHz. So says the datasheet
It should be said that it probably is impossible to hear 15kHz sounds or higher.
Therefor the TDA2003 will work quite alright.
LM1875 works in total hifi league.
1. LM1875 It is superior. Has an upper bandwidth of 300kHz in current drive circuit
2. TDA2030 Has an upper bandwidth of 50kHz in current drive circuit
3. TDA2003 Has an upper frequency of 15kHz. So says the datasheet
It should be said that it probably is impossible to hear 15kHz sounds or higher.
Therefor the TDA2003 will work quite alright.
LM1875 works in total hifi league.
Hello lineup,
thank you for this feedback.
However I use as a main source for music on my first current drive TDA2003 system Internet-Radio.
Radio music in general is cut at 15khz. So if the chip does not make any frequencies above 15khz it is not dramatic.
What I liked most is the benefit of current drive together with conventional fullrange drivers.
The sonic benefit - lower distortion and everything is more articulate and detailed is a great improvement.
Until now I made frequecy response correction dsp assisted to make the sound of fullrange drivers better.
But the benefit of current drive is something new for me and the result is astonishing.
Even a simple chipamp like the TDA2003 makes the sound of a fullrange driver better. If you bring distortion down in percents in loudspeakers it is more important than to fight for better sound on the amplifier side.
And there are thresholds for the audibility of distortion. As I know exactly how distortion sounds in loudspeakers I can tell that the mentioned Pioneer 13cm double cone fullrange driver gets together with current drive a very highendish classy sound.
I chose TDA2003 because I found it works with single power supply.
LM1875 would work with single power supply, too. I found out now. I am very much used to use SMPS power supplys so building a classical supply with a transformer takes me much more time.
thank you for this feedback.
However I use as a main source for music on my first current drive TDA2003 system Internet-Radio.
Radio music in general is cut at 15khz. So if the chip does not make any frequencies above 15khz it is not dramatic.
What I liked most is the benefit of current drive together with conventional fullrange drivers.
The sonic benefit - lower distortion and everything is more articulate and detailed is a great improvement.
Until now I made frequecy response correction dsp assisted to make the sound of fullrange drivers better.
But the benefit of current drive is something new for me and the result is astonishing.
Even a simple chipamp like the TDA2003 makes the sound of a fullrange driver better. If you bring distortion down in percents in loudspeakers it is more important than to fight for better sound on the amplifier side.
And there are thresholds for the audibility of distortion. As I know exactly how distortion sounds in loudspeakers I can tell that the mentioned Pioneer 13cm double cone fullrange driver gets together with current drive a very highendish classy sound.
I chose TDA2003 because I found it works with single power supply.
LM1875 would work with single power supply, too. I found out now. I am very much used to use SMPS power supplys so building a classical supply with a transformer takes me much more time.
I believe in your experience but it would also be nice to see FR and distortion measurements on both configurations, please!?
//
Hello lineup,
you write: It should be said that it probably is impossible to hear 15kHz sounds or higher.
I worked with digital dsp systems like Behringer DEQ2496 which claim to work very correct of what concerns manipulation of certain frequencies (you get what you try to manipulate they say and I measured so, too). I have experience with mini dsp and the dsp in the Behringer Inuke Nu3000dsp amps, too.
If you put up a 31 band EQ on 20khz up you can hear that on a loudspeaker. If you put too much of it, like 2,3 or 4 dbs too much you would dislike it as you can hear how it exaggerates the sound.
I am 52 years old now. If you pass over 30 years of age officially you cannot hear any more 15khz. But my work with DSPs shows me clearly - I have no problems in correcting loudspeakers like fullrange drivers in the area of 10-20khz and you can hear everything you manipulate here. I always use measurement systems for adjusting sound so I know what I change in the frequency response.
Here you can see a 25cm fullrange loudspeaker I made (no tweeters active) dsp controlled. What I cannot hear is the distortion in the high frequencies but the amplitude I have no problem to detect changes in the upper octave. So I let untreated the resonances in the high tones - to be found on the waterfall image.
https://www.diyaudio.com/community/...ion-with-a-2-way.334757/page-364#post-6711184
you write: It should be said that it probably is impossible to hear 15kHz sounds or higher.
I worked with digital dsp systems like Behringer DEQ2496 which claim to work very correct of what concerns manipulation of certain frequencies (you get what you try to manipulate they say and I measured so, too). I have experience with mini dsp and the dsp in the Behringer Inuke Nu3000dsp amps, too.
If you put up a 31 band EQ on 20khz up you can hear that on a loudspeaker. If you put too much of it, like 2,3 or 4 dbs too much you would dislike it as you can hear how it exaggerates the sound.
I am 52 years old now. If you pass over 30 years of age officially you cannot hear any more 15khz. But my work with DSPs shows me clearly - I have no problems in correcting loudspeakers like fullrange drivers in the area of 10-20khz and you can hear everything you manipulate here. I always use measurement systems for adjusting sound so I know what I change in the frequency response.
Here you can see a 25cm fullrange loudspeaker I made (no tweeters active) dsp controlled. What I cannot hear is the distortion in the high frequencies but the amplitude I have no problem to detect changes in the upper octave. So I let untreated the resonances in the high tones - to be found on the waterfall image.
https://www.diyaudio.com/community/...ion-with-a-2-way.334757/page-364#post-6711184
Attachments
I can do distortion measurements with ATB PC 501 system from Leo Kirchner, germany. But as far as I know distortion reduction of current drive has already been technically proved: https://www.current-drive.info/disto/65
If I find the time one day to make measurements I will do them but at the moment I am more into building amplifiers with current drive as these are not commercially available.
Does anyone know if there are affordable commercially available current drive amplifiers out there? Does anybody have a link for me?