a 12v amp, looking for chip - Page 3

Arty · 29th September 2012, 04:26 PM

ah, thatone.
forgot about it, 1557 does not have a diagnostic output.

Actualy You can go with any value as long as it is larger than 10K ohm.
//not even sure its needed if the diagnostic output is not used at all....

Kitax · 30th September 2012, 08:38 AM

well it is needed... i thought that i didnt need it too... that's why i didnt get the 10k rezistor... :P
actually i wanted to change it only because the 4 rezistors didnt look too safe, to leave there... :P

balerit · 30th September 2012, 11:44 AM

Quote:

Originally Posted by balerit

Well that's why I designed my amp with an input buffer, you can increase the gain if need be. If you have to add a preamp then use a TDA 7630 or TDA1524 and build a dedicated preamp. I use the TDA 7630 in my Camm EquiTone preamp and it is the best preamp that I have heard. I am currently building a new preamp to test the TDA1524 chip.

Arty I stand corrected on the 8560, the 1562 is an class H amplifier.

DIY Preamplifier - The Book Worm

Mac

Sorry guys, the preamp ic is TA7630p, got too many tda's in my head

Arty · 30th September 2012, 12:28 PM

just stick to passive tone controlls.
chip has enough beef to handle it.
Maybe as a way of improving it a buffer could help.

Kitax · 3rd October 2012, 02:47 PM

i want to calculate, how fast my 7Ah battery is going to hold the tda8560q on various input voltages, how should i do that?

Arty · 3rd October 2012, 07:05 PM

so.. say You drive 4 ohm speakers.
from a single 12v battery this chip will have something like 8v max output voltage.
we assume this swing.
so, 8/4 = 2A current.
this is stereo, so it will be closer to 4 A.
7/4 is 1,75 hours at full blast volume.
Does not sounds a lot.
but consider, that You will more than sure not run it at full blast.
I would estimate at least 3 hours of loud music.

//notice, one may argue that the amp has a certain % of efficiency, and a number of losses are to be included. But allso notice that speakers have impedance, my estimation is based on an ohmic load and constant current draw. //

Kitax · 4th October 2012, 01:00 PM

where did you get the 8v output?

Arty · 4th October 2012, 02:13 PM

see datasheet.
test condition RL = 4 ohm
output power = 17w @10% THD.
P = U*I
P as power, U as voltage, and I as current.
I = U/R
where R is our load.
so P = Uˇ2/R
or sqrt(P*R) = U
witch is sqaure root of 68.
A tiny bit over 8 volts.

btw, it was only estimated.
Real life figures will differ.
It will be less output voltage since 10% THD sounds terrrible.
I would say that from a single 12v rated battery 8 volt output swing is on the edge.
Most likely You won't even utilise half of it.
It will be loud enough, given You use more or less efficient speakers.

sofaspud · 4th October 2012, 02:58 PM

It may sound odd, but a 7Ah SLA isn't likely to provide 7 amps for an hour, or 3.5 amps for two hours, or even 2.33 amps for three hours.

Kitax · 4th October 2012, 06:22 PM

well you could have just sait "the datasheet"couse i know how to do the math but thanks anyways ^_^

and sofaspud: that doesnt surprize me at all, but how do you explain it?

4th October 2012, 02:58 PM	#29
sofaspud diyAudio Member Join Date: Nov 2005 Location: San Antonio	It may sound odd, but a 7Ah SLA isn't likely to provide 7 amps for an hour, or 3.5 amps for two hours, or even 2.33 amps for three hours. __________________ It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

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29th September 2012, 04:26 PM	#21
Arty diyAudio Member Join Date: Feb 2011	ah, thatone. forgot about it, 1557 does not have a diagnostic output. Actualy You can go with any value as long as it is larger than 10K ohm. //not even sure its needed if the diagnostic output is not used at all....

30th September 2012, 08:38 AM	#22
Kitax diyAudio Member Join Date: Sep 2012 Location: Riga	well it is needed... i thought that i didnt need it too... that's why i didnt get the 10k rezistor... :P actually i wanted to change it only because the 4 rezistors didnt look too safe, to leave there... :P

30th September 2012, 12:28 PM	#24
Arty diyAudio Member Join Date: Feb 2011	just stick to passive tone controlls. chip has enough beef to handle it. Maybe as a way of improving it a buffer could help.

3rd October 2012, 02:47 PM	#25
Kitax diyAudio Member Join Date: Sep 2012 Location: Riga	i want to calculate, how fast my 7Ah battery is going to hold the tda8560q on various input voltages, how should i do that?

3rd October 2012, 07:05 PM	#26
Arty diyAudio Member Join Date: Feb 2011	so.. say You drive 4 ohm speakers. from a single 12v battery this chip will have something like 8v max output voltage. we assume this swing. so, 8/4 = 2A current. this is stereo, so it will be closer to 4 A. 7/4 is 1,75 hours at full blast volume. Does not sounds a lot. but consider, that You will more than sure not run it at full blast. I would estimate at least 3 hours of loud music. //notice, one may argue that the amp has a certain % of efficiency, and a number of losses are to be included. But allso notice that speakers have impedance, my estimation is based on an ohmic load and constant current draw. //

4th October 2012, 01:00 PM	#27
Kitax diyAudio Member Join Date: Sep 2012 Location: Riga	where did you get the 8v output?

4th October 2012, 02:13 PM	#28
Arty diyAudio Member Join Date: Feb 2011	see datasheet. test condition RL = 4 ohm output power = 17w @10% THD. P = UI P as power, U as voltage, and I as current. I = U/R where R is our load. so P = Uˇ2/R or sqrt(PR) = U witch is sqaure root of 68. A tiny bit over 8 volts. btw, it was only estimated. Real life figures will differ. It will be less output voltage since 10% THD sounds terrrible. I would say that from a single 12v rated battery 8 volt output swing is on the edge. Most likely You won't even utilise half of it. It will be loud enough, given You use more or less efficient speakers.

4th October 2012, 06:22 PM	#30
Kitax diyAudio Member Join Date: Sep 2012 Location: Riga	well you could have just sait "the datasheet"couse i know how to do the math but thanks anyways ^_^ and sofaspud: that doesnt surprize me at all, but how do you explain it?