Exactly. It's the same as with GNFB. A low open loop distortion amplifier still will be a better amp than a high distortion design with the same amount of GNFB. A high offset amp design still will show higher offset with the servo as a low offset layout with servo.
Best regards!
Best regards!
Hi....
Finally i got it all cleaned proberly and mounted on my testrig.
I started with @Mark Johnson BellRinger to eliminate any ringing from this very nice xformer from the Polish Toroidy.
I must say again, that this factory and support is top notch for sure. No hum, no difference between windings and completly silency being in the same room as it 😵
DC Offset is down around 5 mA/Left & 6mA/Right (R15 is 47.5Kohm)... Can't hear any noise or hum at speakers. Voltage +35.5 // -35.5
Nothing get warm at moment.
I will do some more testing this weekend, right now just listning to Hell freezes over...
I also will try to figure out howto meassure ripple with the scope.
-Anybody know a good way doing this, maybe with amp. connected as now ?
Regards;
Jesper.
Finally i got it all cleaned proberly and mounted on my testrig.
I started with @Mark Johnson BellRinger to eliminate any ringing from this very nice xformer from the Polish Toroidy.
I must say again, that this factory and support is top notch for sure. No hum, no difference between windings and completly silency being in the same room as it 😵
DC Offset is down around 5 mA/Left & 6mA/Right (R15 is 47.5Kohm)... Can't hear any noise or hum at speakers. Voltage +35.5 // -35.5
Nothing get warm at moment.
I will do some more testing this weekend, right now just listning to Hell freezes over...
I also will try to figure out howto meassure ripple with the scope.
-Anybody know a good way doing this, maybe with amp. connected as now ?
Regards;
Jesper.
Jesper
I have initially started with 47.5 Kohm but 10K R15 has reduced the offset significantly.
Your amp looks brilliant, tidy. 👍It appears that we use the literally the same components. I have ordered with Mausers shopping from #1.
It would be fine to see your measurement results. I have similar oscilloscope and we could verify and compare the results. Do you have a THD measuring rig?
Looking forward to see your progress.
Have a pleasant weekend! 🙂
I ran some FFT test today.
Normally i use my Victor's excellent 1KHz osc., but i couldn't avoid some 50Hz + 2..3.. harmonics from it in this setup.
(I know from experience that's it's much better, boxed all up)
For a long time i allways wanted to try using my Topping dac to feed such setup, and i did that just yet, knowing that the Topping have vanishing low THD+N's
So for sure we can say that the result is what the XmasDUT tells REW.
This first FFT was taking with Xmas amp. loaded with 8ohm, 1KHz sine @ 2.80vac (1W)
Rest of the settings can be seen on the screenshot.
Looking forward to see how your'e perform's @Berlusconi
Later i will meassure some ripple from the PSU with both channels loaded @ 1W.
Jesper.
Normally i use my Victor's excellent 1KHz osc., but i couldn't avoid some 50Hz + 2..3.. harmonics from it in this setup.
(I know from experience that's it's much better, boxed all up)
For a long time i allways wanted to try using my Topping dac to feed such setup, and i did that just yet, knowing that the Topping have vanishing low THD+N's
So for sure we can say that the result is what the XmasDUT tells REW.
This first FFT was taking with Xmas amp. loaded with 8ohm, 1KHz sine @ 2.80vac (1W)
Rest of the settings can be seen on the screenshot.
Looking forward to see how your'e perform's @Berlusconi
Later i will meassure some ripple from the PSU with both channels loaded @ 1W.
Jesper.
Here is a shoot of 10vac input to the 8ohm's powerresistor's.
My ripple measured with a good quality DMM is allmost anytime with different loads = 1.9mVac, (circa from 1vac sine ... to 15vac sine) witch i think is good enough.
Jesper.
EDIT :: My hacked Behringer accept's 10's of volts directly on input without voltage divider's, which is very nice to have!
My ripple measured with a good quality DMM is allmost anytime with different loads = 1.9mVac, (circa from 1vac sine ... to 15vac sine) witch i think is good enough.
Jesper.
EDIT :: My hacked Behringer accept's 10's of volts directly on input without voltage divider's, which is very nice to have!
Hi @lykkedk
Absolutely remarkable results and equipment!
It is important to observe that you have achieved excellent results at 1WRMS which is a good news, at least for me, because I was somewhat concerned/worried with the data from the data sheet which indicate higher distortion at lower output power and that the best results regarding THD can be attained at higher power output. This means that the stock design isn't adequate for silent passages. For me it is important to have low distortion in silent passages because my preference is classical music which requites very large dynamic range from ppp to forte fortissimo.
For the time being I measure slightly higher THD values, probably because there is some problem left to be rectified. I have used the 1st version of the board and there must be solution to this issue published here in this thread but I haven't found it yet.
Your measurement results do encourage me and I appreciate that.
Regarding the sine wave source I totally agree: it is of paramount importance to provide a clean signal to obtain realistic results. I have noticed it when I've tested my new DIY DAC based on XingCore USB Digital Interface PCM1536 DSD1024. The results were so good that I've decided to build it with two linear power supplies, one even for the digital part. This is, however, project in progress and meanwhile I still use Xonar U7 MKII which is very good, but not good enough.
I have extremely busy week in front of me, but as soon I get back to the bench I intend to resume my measurements of this indeed promising amplifier.
Thank you for publishing your experimental data.
I wish you a pleasant Sunday
Absolutely remarkable results and equipment!
It is important to observe that you have achieved excellent results at 1WRMS which is a good news, at least for me, because I was somewhat concerned/worried with the data from the data sheet which indicate higher distortion at lower output power and that the best results regarding THD can be attained at higher power output. This means that the stock design isn't adequate for silent passages. For me it is important to have low distortion in silent passages because my preference is classical music which requites very large dynamic range from ppp to forte fortissimo.
For the time being I measure slightly higher THD values, probably because there is some problem left to be rectified. I have used the 1st version of the board and there must be solution to this issue published here in this thread but I haven't found it yet.
Your measurement results do encourage me and I appreciate that.
Regarding the sine wave source I totally agree: it is of paramount importance to provide a clean signal to obtain realistic results. I have noticed it when I've tested my new DIY DAC based on XingCore USB Digital Interface PCM1536 DSD1024. The results were so good that I've decided to build it with two linear power supplies, one even for the digital part. This is, however, project in progress and meanwhile I still use Xonar U7 MKII which is very good, but not good enough.
I have extremely busy week in front of me, but as soon I get back to the bench I intend to resume my measurements of this indeed promising amplifier.
Thank you for publishing your experimental data.
I wish you a pleasant Sunday
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As I only use fullrange drivers which profit from current drive what brings distortion in loudspeakers down by 10 to 20 decibels.
Will there be a pcb version of this nice TDA7293 amp with current drive?
If it only needs a little change I would be grateful to learn what to change but to get the desired outcome.
(Change in the schematic on the first page of this thread).
Will there be a pcb version of this nice TDA7293 amp with current drive?
If it only needs a little change I would be grateful to learn what to change but to get the desired outcome.
(Change in the schematic on the first page of this thread).
I was about to order the TO-264 ceramic insulator, but they are available in 1mm and about 0.6mm.
Which ones are more suitable? Don't the 0.6mm break too quickly?
Which ones are more suitable? Don't the 0.6mm break too quickly?
Just a quick update...
I put an 22K resistor across the R15, giving around 15K (47.5K || 22K), and this lovered the offset from ~5mV to 0.8mV.
So i will pull the 47.5K out and solder a 10K in to test it out, when i'am done testing.
Jesper.
Have you found "DC coupling" setting on your Rigol oscilloscope? You can investigate ripple with that option because DC coupling measures just AC.
@Berlusconi ...
Actually I did not try that yet, I only measured the ripple with an good quality DMM set at AC.
Will for sure look into this.
Jesper...
Actually I did not try that yet, I only measured the ripple with an good quality DMM set at AC.
Will for sure look into this.
Jesper...
Yes, but your quote is quite the opposite of what you wrote in #932. You need the AC coupling setting for measuring ripple, not the DC one 😉 .
Best regards!
Best regards!
@Kay Pirinha
My bad. 😡
It was so easy to see the lapse of tongue, and more importantly, readiness to help, what is the real purpose of this discussion board.
But, let's get back to the subject of this conversation and stop finding faults, however small or unimportant, everywhere you may look.
My bad. 😡
It was so easy to see the lapse of tongue, and more importantly, readiness to help, what is the real purpose of this discussion board.
But, let's get back to the subject of this conversation and stop finding faults, however small or unimportant, everywhere you may look.
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Huston! We have a problem!
My TDA 9273 project went a little bit wider than testing just one board. I wanted to compare three different boards to find out which is the best among the chosen candidates:
I was expecting that Xmass Amp will sweep with the competition but it was quite the opposite.
The winner was:
TDA7293 power Amplifier PCB 60W*2(OCL) 120W*1 (BTL)
You can see the best results from the Figure 1. below.
Results for Xmass Amp are shown in Figure 2.
I have made sure that measurements were made under the same conditions.
Initially, I have hesitated to publish the results hoping to find the solution alone.
However, I am sure there is solution to this because at least two results published here indicate that this amplifier may produce much better results.
I have used the gerbers from the OP and Shopping basket at Mouser.
Both channels of Xmass Amp have the same highish THD results as well as all other parameters..
The only change I’ve made is R15=10K.
My questions are:
Q1. Is there anything in the 1st version of the board that increases the THD?
Q2. Is there any change that should be applied to the 1st version of the board?
Fig. 1. TDA 7293 – 2OCL 1BTL at 10 VRMS into 5.5 Ohm
https://www.diyaudio.com/community/attachments/tda7293-10vrms-jpg.1130340/
Fig. 2. Xmass Amp at 10 VRMS into 5.5 Ohm
My TDA 9273 project went a little bit wider than testing just one board. I wanted to compare three different boards to find out which is the best among the chosen candidates:
- Xmass Amp
- TDA7293 Parallel kit from ebay (https://www.diyaudio.com/community/...lave-style-no-lossy-emitter-resistors.211746/)
- TDA7293 power Amplifier PCB 60W*2(OCL) 120W*1 (BTL)
I was expecting that Xmass Amp will sweep with the competition but it was quite the opposite.
The winner was:
TDA7293 power Amplifier PCB 60W*2(OCL) 120W*1 (BTL)
You can see the best results from the Figure 1. below.
Results for Xmass Amp are shown in Figure 2.
I have made sure that measurements were made under the same conditions.
Initially, I have hesitated to publish the results hoping to find the solution alone.
However, I am sure there is solution to this because at least two results published here indicate that this amplifier may produce much better results.
I have used the gerbers from the OP and Shopping basket at Mouser.
Both channels of Xmass Amp have the same highish THD results as well as all other parameters..
The only change I’ve made is R15=10K.
My questions are:
Q1. Is there anything in the 1st version of the board that increases the THD?
Q2. Is there any change that should be applied to the 1st version of the board?
Fig. 1. TDA 7293 – 2OCL 1BTL at 10 VRMS into 5.5 Ohm
https://www.diyaudio.com/community/attachments/tda7293-10vrms-jpg.1130340/
Fig. 2. Xmass Amp at 10 VRMS into 5.5 Ohm