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Old 17th February 2015, 06:18 PM   #1
mitsof is offline mitsof  Greece
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Default How to bring this amp to maximum power?

I've built this amp based on the tda7360 chip and I would like to bring it to full power.I'm using my laptop as audio source.

The laptop measures 1.1 volts AC at the headphones output when playing a 200Hz sine wave at full volume.I suppose this is the Vrms.

The TDA's voltage gain (input sensitivity) is 26 dbs in bridge arrangement according to the datasheet.

According to my calculations this amp needs -4.7dbs at its input if I am correct.

I seem to be missing something here.Is this number all I need?To my knowledge the gain and the circuitry of the amp also affect its input sensitivity.

How to match this amp to my laptop to bring it to full power?
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Old 17th February 2015, 08:32 PM   #2
orbanp is offline orbanp  Canada
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The chip would give 20W power (P) in the bridge configuration with 4 Ohm load (Rl).
From this the output voltage V = sqrt(P * Rl) = sqrt(20 * 4) = 8.94V
26dB gain is 20 times amplification (Au).
To get the full output power you need an input voltage Vin = V / Au = 8.94 / 20 = 0.44V
This means that the full output voltage from the laptop can even overdrive the amp.

Good luck, Peter

Last edited by orbanp; 17th February 2015 at 08:35 PM.
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Old 18th February 2015, 05:22 AM   #3
mitsof is offline mitsof  Greece
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Quote:
Originally Posted by orbanp View Post
The chip would give 20W power (P) in the bridge configuration with 4 Ohm load (Rl).
From this the output voltage V = sqrt(P * Rl) = sqrt(20 * 4) = 8.94V
26dB gain is 20 times amplification (Au).
To get the full output power you need an input voltage Vin = V / Au = 8.94 / 20 = 0.44V
This means that the full output voltage from the laptop can even overdrive the amp.

Good luck, Peter
Thanx for the answer.One more question.What if there is open loop gain voltage and closed loop gain voltage in the datasheet?like the TDA2050.It has open loop gain voltage 80db and closed loop about 30 db.Which one should I use for the calculations you gave?
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Old 18th February 2015, 08:41 AM   #4
djk is offline djk
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Closed loop.

Give yourself some overdrive capability, I suggest 6dB or so.
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Old 18th February 2015, 07:40 PM   #5
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mitsof

You need to study electronics a bit more before placing this type of questions and then again you need to study principal of operation of the specific IC while hot for you will be to understand the limitations and the limiting mechanism of the IC

For sure you don't have a gain issue More likely you have an overestimation issue of what this chip can really do

Chips like that often present output power ideally high BUT under specific conditions IE specific load /power supply /distortion /and or time This is were your problem lays .

Farther more more than 50% of the things you describe in your blog are to be removed .Obviously its your blog you may write anything you wish but its not nice to younger people that seek knowledge and if they find your blog they will read things written in a very wrong way .

Regards
Sakis
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Old 18th February 2015, 07:51 PM   #6
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I think this thread belongs in the chip-amp section/
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Old 18th February 2015, 08:22 PM   #7
mitsof is offline mitsof  Greece
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Quote:
Originally Posted by east electronics View Post
mitsof

You need to study electronics a bit more before placing this type of questions and then again you need to study principal of operation of the specific IC while hot for you will be to understand the limitations and the limiting mechanism of the IC

For sure you don't have a gain issue More likely you have an overestimation issue of what this chip can really do

Chips like that often present output power ideally high BUT under specific conditions IE specific load /power supply /distortion /and or time This is were your problem lays .

Farther more more than 50% of the things you describe in your blog are to be removed .Obviously its your blog you may write anything you wish but its not nice to younger people that seek knowledge and if they find your blog they will read things written in a very wrong way .

Regards
Sakis
Ρε άντε κάνε παραπέρα που ήρθες κι εδώ να μου πεις να διαβάσω.Πίσω στο φόρουμ με τους παπάρες.Εδώ οι άνθρωποι είναι σοβαροί.Δίνουν συγκεκριμένες απαντήσεις.

Ανώμαλος είσαι;Ακομά κι εδώ ρε;χαχαχα.Πίσω στο μαντρί.

Last edited by mitsof; 18th February 2015 at 08:26 PM.
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Old 18th February 2015, 08:33 PM   #8
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This is an english speaking forum and yes this was my opinion ...

( i have seen your attempts in the Greek forum where you asked information for a preamplifier with gain of 40db in order to increase the output power of your amplifier ... so yes i think you need to do some reading )
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Last edited by east electronics; 18th February 2015 at 08:36 PM.
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Old 18th February 2015, 08:34 PM   #9
mitsof is offline mitsof  Greece
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Quote:
Originally Posted by east electronics View Post
This is an english speaking forum and yes this was my opinion ...
Τσίτ από δω.χαχαχ
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Old 18th February 2015, 08:41 PM   #10
mitsof is offline mitsof  Greece
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Quote:
Originally Posted by east electronics View Post
This is an english speaking forum and yes this was my opinion ...

( i have seen your attempts in the Greek forum where you asked information for a preamplifier with gain of 40db in order to increase the output power of your amplifier ... so yes i think you need to do some reading )
Αλλά το πραγματικό πρόβλημα των μαστόρων στην Ελλάδα ξέρεις ποιό είναι. Σας έχω φάει στη μάπα χρόνια και ξέρω τί καπνό φουμάρετε.Άμα βλέπετε κανέναν να στρίβει καμιά βίδα σας χαλάει την πιάτσα και θέλετε να τον φάτε.Γιατί δεν είναι μάστορας.Δεν είναι δυνατόν να ξέρει να στρίψει βίδα.Πρέπει να ρθεί σε σας να πληρώσει.

Last edited by mitsof; 18th February 2015 at 08:43 PM.
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