[DIY] Amplifier IC upgrade

[aidilj]

Hi Guys,Another DIY for those interested. Upgrading the stock head unit amplifier IC to a better one. Head unit is a Philips BMW business cassette. Here are the ICs datasheet:Original - TDA7385 - 4x37W quad bridge amplifierUpgrade - TDA7560 - 4x50W quad bridge amplifierHead unit

Connector

Amplifier board

Stock amplifier IC, TDA7385, designed for 4ohm load. I thought our speakers are supposed to be 2ohm?

Replacement IC, TDA7560, capable of driving 2ohm load up to 77W

IC removed

Heat paste

Big ass cap

Done

Now I just need new pairs of speakerCheers

 

[wan520i]

Nice jobs, nice pictures!
You should use heat shrink on the cap. where you get the replacement IC and how much?
What made you say that your speaker are 2 ohm? The OEM speakers should be 4 ohms, if not 8 ohms.

 

[aidilj]

Nice jobs, nice pictures!
You should use heat shrink on the cap. where you get the replacement IC and how much?
What made you say that your speaker are 2 ohm? The OEM speakers should be 4 ohms, if not 8 ohms.

Hey wan, yeah I should use heat shrink, insulator tape is so 70's. I should really move to heat shrink. Saw some at the nearby electronic shop and they're not cheap.

This is not the first time I upgraded an amplifier IC to TDA7560. Previously I got it from Leader Electronics in Melaka. But the chip is not available in Penang it seems so I this time around its from eBay from some guy in Hong Kong. In KL, components would be abundant at Jln Pasar.

I've checked mine at they're 4ohm. Lots of online discussions say its 2ohm and even our own Bro Jarance here
http://www.bmwclubmalaysia.com/forums/showpost.php?p=412499&postcount=2

Then I just thought maybe they have different speced system - with premium audio perhaps.

 

[jarance]

yup, it confirm 2 ohms for the mid-range speaker. was Trying to upgrade but could not find at the shop when they took it out.Finally got it cheap when AB have cheap sale. Still keeping it at home. have not get around to fix it yet.

btw, how the sound clarity. Any distortion as compare to ori amp. why you need to add the cap?

 

[aidilj]

I'm putting the cap to hopefully give the IC enough power when it needs it. On trial run, the heat sink is super hot that's why I supplemented the existing cap with another one.

I'm getting distortion now at the speakers thinking that the speakers can't handle the power. I will do further investigation this weekend. I just think that the sound clarity can be much better with aftermarket speakers. Currently the speaker sounds like they're gonna tear apart, you can hear the speaker so paper-like.

I have the same amplifier IC modded into another car's head unit with 4x 2-way kenwood, they sounds good. I've talked to a shop, they said kenwood gives most bass and I agree.

 

[jarance]

I'm putting the cap to hopefully give the IC enough power when it needs it. On trial run, the heat sink is super hot that's why I supplemented the existing cap with another one.

I'm getting distortion now at the speakers thinking that the speakers can't handle the power. I will do further investigation this weekend. I just think that the sound clarity can be much better with aftermarket speakers. Currently the speaker sounds like they're gonna tear apart, you can hear the speaker so paper-like.

I have the same amplifier IC modded into another car's head unit with 4x 2-way kenwood, they sounds good. I've talked to a shop, they said kenwood gives most bass and I agree.

you might consider to check the speaker first. I also have some sound problem as well. When I open the speaker, I found that the glue edges have comes off. A quick fix with UHU glue and it sound so much better.

 

[wan520i]

Currently the speaker sounds like they're gonna tear apart, you can hear the speaker so paper-like.

This happened at what volume? volume set more than 50%?

Is not a good sign if you faced the above at low volume. It should not happened eventhough your output power has increased by changing the IC, your ori speakers should be still able to handle it, unless your amp is huge with 1000 watts ouput.

 

[aidilj]

This happened at what volume? volume set more than 50%?

Is not a good sign if you faced the above at low volume. It should not happened eventhough your output power has increased by changing the IC, your ori speakers should be still able to handle it, unless your amp is huge with 1000 watts ouput.

Totally agree with you Wan that the speaker should still be able to handle the power. The distortion seems to also happen at lower volume. Pretty worried about this as well, other suspect for this would be insufficient heatsinking, broken or knockoff IC. Experiment this weekend would include putting in aftermarket speaker.

 

[aidilj]

This happened at what volume? volume set more than 50%?

Is not a good sign if you faced the above at low volume. It should not happened eventhough your output power has increased by changing the IC, your ori speakers should be still able to handle it, unless your amp is huge with 1000 watts ouput.

If you are asking about the speaker sounds like tearing apart yes, definitely higher than 50% volume. But with the stock radio I couldn't be so sure since there is no indicator at which level you're at

 

[wan520i]

I just worry some passive or active components that located at input or output of the IC may not compatible, do you have specs sheet for the new IC? sometime it has simple circuit diagram, check and see..

Good luck to you.

 

[aidilj]

I just worry some passive or active components that located at input or output of the IC may not compatible, do you have specs sheet for the new IC? sometime it has simple circuit diagram, check and see..

Good luck to you.

The datasheet of both ICs are linked in the first post. They both have the same/very similar standard application circuit thus my confidence in impedance matching on input to the IC and out. I've also removed some components that I disagree with from the board at the output portion. Measuring the speaker impedance is next.

Thanks Wan

 

[wan520i]

Refer to figure 1-Block diagram for both datasheets, there are 2 locations use different parts >> Top right at VCC2 (2.200 uf vs 470 uf ) and botom left AC-GND (0.1 uf vs 0.47 uf ).
Could these be the culprits?

 

[aidilj]

Instead of figure 1, I'm looking at figure 3 of both datasheet. I've always noticed the different capacitor value at AC-GND of both ICs and thought the difference is negligible. Need to scour my part box for this 0.47uF cap if anything else doesn't work. Thanks very much Wan.

 

[aidilj]

Look at what I've found: a couple of 50V 0.47uF polar cap, guess I'll be swapping the capacitor first before doing anything else. :biggrin:

 

[perryyip73]

SUperb GURU, thanks for the tips !

 

[aidilj]

Update:

After the morning experiment it is concluded that the stock heatsink couldn't cope with the heat generated by the IC. Class AB amplifier never is an efficient amplifier. All parasitic components around the IC was removed and it sounds great until the IC heats up then sound would be distorted.

It is also concluded that impedance seen by the head unit on the speakers are 4ohm. I've removed the rear deck speaker and it has 4ohm stamped on it. The front speaker was not physically removed but from the radio connector, resistance of front and rear are the same. If the door mid range is 2ohm, probably it is connected in serial with the tweeter.

While also checking on the resistance it is found that the wiring for the front speakers are incorrect - suspected that previous owner changed to aftermarket then put back OEM head unit before selling and wireman doesn't do a great job. Explains why left/right balance setting doesn't really set the balance. Fixed.

For reference here is the pinout for my headunit, might be applicable for you too.

Cheers

 

[jarance]

yup, it confirm 2 ohms for the mid-range speaker. was Trying to upgrade but could not find at the shop when they took it out.Finally got it cheap when AB have cheap sale. Still keeping it at home. have not get around to fix it yet.

btw, how the sound clarity. Any distortion as compare to ori amp. why you need to add the cap?

Sorry guys, just check the new speaker that I have bought. It actually is 4 ohms and not 2 ohms was claimed by BMW WDS.

 

[IanDaddy]

Jarance, where did you get the speaker ? How much is it ? I am contemplating importing the BSW drop-in replacement for my E46 (10 speakers).

Thanks

 

[jarance]

Ian, got it from Auto Bavaria (Glenmarie) cheap sales. I think it was 70% off the list price. about RM60.00.

 

[aidilj]

Jarance, where did you get the speaker ? How much is it ? I am contemplating importing the BSW drop-in replacement for my E46 (10 speakers).

Thanks

Whoa Ian, the BSW drop in stage 1 is $599! Will it worth it?