TDA7386 Car Amp - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th September 2008, 06:16 PM   #11
diyAudio Member
 
Join Date: Aug 2008
Here's the reference schematic:
Attached Images
File Type: jpg tda7560 schematic.jpg (37.1 KB, 455 views)
  Reply With Quote
Old 10th September 2008, 02:58 AM   #12
diyAudio Member
 
Join Date: May 2008
the other thing you might want to note, is with 12 volt input your only going to get around 15w output, maybe as high as 20w with an alternator running.

thats why car amplifiers in the 40+w range use switching power supplys to boost voltage

youll notice this in the datasheet for the TDA7386.
according to the datasheet, with 18v input you will get 35w output into 4 ohms at 1% THD.
  Reply With Quote
Old 10th September 2008, 09:34 AM   #13
diyAudio Member
 
Join Date: Aug 2008
Actually I'm using the TDA7560, re: some messages near the top of the thread. Accordingly, it should put out 15W at 1% at 11.5V that I was testing with. I hooked up a 0.5W speaker, and it was still barely audible with the source at max volume (about 0.5V p-p). I was able to get decent volume only with 8V p-p source, but it wasn't loud enough for an automobile environment.

The front speakers I'm driving are fairly efficient, 35W 92dB sensitivity. Should be plenty of power. If I find I don't have enough power for the rear woofers, I'll make another amp just for them.
  Reply With Quote
Old 10th September 2008, 10:03 AM   #14
diyAudio Member
 
Join Date: May 2008
According to the datasheet the TDA7560 has a voltage gain of 26dB i. e about 20 times the input voltage. Your 0.5V input should have given you nearly 10V output, being 25W into 4 Ohm, if your power supply is up to it.

Did you check, if the mute and standby pins have more than 3.5V present?

Where did you measure the 0.5V? Directly at the input pins?

Did you try, if it works better, if you bypassed the input caps?
  Reply With Quote
Old 10th September 2008, 01:19 PM   #15
diyAudio Member
 
Join Date: Aug 2008
I didn't measure the 0.5V, I was taking it from the specs of my source. Yes I measured mute and standby pins. Standby works, it's not hooked up, so I was connecting and disconnecting it. Mute is tied to Vcc. The spec sheet says if mute is enabled, there's about 90dB attenuation. Which is what it sounds like, but mute should not be enabled. Oh, and yes I tried bypassing the input caps, among other things.
  Reply With Quote
Old 18th May 2009, 04:01 PM   #16
strajo is offline strajo  Serbia
diyAudio Member
 
Join Date: Mar 2009
I now it is to late to discus about, but nevermind, here is my expirience with tda7386 as car amplifier.

I would like to use 7386 as power amplifier, and as preamp I used active crosover based on dr.Borivoje Jagodic TOCATA II system (http://bas.elitesecurity.org/mojiprojekti1.html) . Preamp worked very well, and if someone is interested i have my own pcb developed for it (cdr file, single layer, proved to work).

The basic idea is to have two 7386, two preamp boards, which gives 8 speakers, lets say, : 2 high, 2 midrange and 4 low speakers which should give very important sound pressure.

I managed to make one block (preamp pcb + power supply pcb with positive to negative voltage converter for op amps, and relays for overall power control + pcb with 7386)

For test, I used pioneer car cd player, atx power supply.

Hooked up everything, everything worked..BUT..

there is some little noise from power suply, and ground loop problem when conected signal in. Poweramp schematics is from original datasheet.

Then I used little transformators found on old modem PCI cards (1:1 similar) as ground loop isolator and they worked very well. Is there some other way?

Heatsink.

I 'm using heatsink from pentium IV processor, square one, and just realised that i need to cool it. Ok, PC Proccessor fan with some thermostat schematics will do the job, but when fan starts there is again a little noise hearing from speakers. Fan makes noise.

Ok, I know that you'll say why not to use passive cooling, say large heatsink and so on, but I don't know how large it should be. What is the minimum surface, and let's say that there is not maximum surface.

When I say little noise I realy mean little, but I would like to eliminate it.

For now, everything is on my workshop desk..need some time for car testing...wife, kids...job..., and yes..I'll post pcb-s, schematics and everything..as I sad before..need some time for real environement testings.

Someone with similar noise problems?
  Reply With Quote
Old 18th May 2009, 06:55 PM   #17
diyAudio Member
 
Join Date: May 2008
Quote:
Originally posted by strajo
there is some little noise from power suply,
What kind of noise? Hum, buzz or hiss or..?

Quote:
Originally posted by strajo
Then I used little transformators found on old modem PCI cards (1:1 similar) as ground loop isolator and they worked very well. Is there some other way?
- Rework the grounding. Make separate grounds for signal and power. Connect them through a small resistor. Check for ground loops and interrupt them.
- http://sound.westhost.com/earthing.htm
- Search the Forum. There are several threads dealing with ground loops.

Quote:
Originally posted by strajo
I 'm using heatsink from pentium IV processor, square one, and just realised that i need to cool it. Ok, PC Proccessor fan with some thermostat schematics will do the job, but when fan starts there is again a little noise hearing from speakers. Fan makes noise.
Is that fan connected to the same power supply as the amplifiers? Then connect it to a different power supply.

Quote:
Originally posted by strajo
Ok, I know that you'll say why not to use passive cooling, say large heatsink and so on, but I don't know how large it should be. What is the minimum surface, and let's say that there is not maximum surface.
Depends on the ambient temperature and the speaker impedance. The datasheet shows ~38 W power dissipation, when loaded with 4 x 4 Ohm. That means a heatsink with 1,2 K/W for 20C and 0,7 K/W for 40C. With 8 Ohm speakers the dissipation is more or less half that figure. There is a rule of thumb that says 10 cm for each W of power dissipation, that would be 380 cm for each of those TDA7386.[/B][/QUOTE]
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 19th May 2009, 02:11 PM   #18
strajo is offline strajo  Serbia
diyAudio Member
 
Join Date: Mar 2009
thanks man for quick post.

I thing that my problem with earth loop is that I used same gnd points for sig gnd as for pwr gnd..I'll try adding small resistor, say 10 ohm.

Another thing, that cooling fan takes positive potential from regulated power supply (7812), and it's regulated 12V is used for preamp positive powering. (while lm2575t-12 is used for positive/negative converter for preamp op amps.).


Few minutes ago I solved its noise by adding 2200uF elektrolythic capacitor in paralel and 10 ohm resistor in series: fan - capacitor - resistor - positive.

I'll revork grounding, and I would ask you for opinion about Redshift187' s tda schematics from start of this post. That R9,10 ohm resistor...is it there for ground loop problems?

Other noise problems...that little noise from power supply is buzz and comes mainly from atx power supply fan...

I should put it all in car for real testing...I'll post results.


thanks again
  Reply With Quote
Old 19th May 2009, 03:14 PM   #19
diyAudio Member
 
Join Date: May 2008
Quote:
Originally posted by strajo
I'll revork grounding, and I would ask you for opinion about Redshift187' s tda schematics from start of this post. That R9,10 ohm resistor...is it there for ground loop problems?
R9 is the resistor that separates signal and power ground, the same you want to add.

Quote:
Originally posted by strajo
Other noise problems...that little noise from power supply is buzz and comes mainly from atx power supply fan...

I should put it all in car for real testing...I'll post results.
You won't get buzz in a car, because the power supply is DC. With a ground loop in a car you will get a howling noise that depends on the alternator speed (= motor rpm). Make sure that all audio equipment is grounded at the same point in the car and make the ground wire to the amplifier as thick as possible.
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 21st May 2009, 11:16 AM   #20
strajo is offline strajo  Serbia
diyAudio Member
 
Join Date: Mar 2009
Believe or not, preamp circuit picks noise and feed it to TDA...no matter what to do, even adding R9 for separating sig gnd and real gnd, noise is still there. Somehow I burned my preamp, as so as that LM2575-12 used as -12v generator. But nevermind, after all...it is normal, when developing something I'll build new one..it is relatively cheap. Already have pcb..

Good news : when I removed pwr amp inputs, and power up only TDA, there is no noise at all.

So, remember those transformers from pci modem cards...I will surely remove them, and for RCA inputs, considering balanced line driver and receiver from http://sound.westhost.com/project51.htm.

What do you think..will that be helpful.

BTW, thanks for link..great site.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Help with TDA7386 jorge_rc Chip Amps 8 20th June 2012 07:46 PM
PCB for TDA7386 Amplifier enecumene Chip Amps 1 16th May 2009 02:19 PM
TDA7386 Problem please help Brownstocker Chip Amps 5 28th January 2008 10:02 PM
Tda7386 koloko Chip Amps 1 18th June 2007 08:25 AM
Problem with TDA7386 SideWinder Chip Amps 0 24th May 2004 10:13 AM


New To Site? Need Help?

All times are GMT. The time now is 06:06 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2