TDA7498 Upgrade suggestions

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Hello all,
I am looking for suggestions in upgrading the components on my TDA7498 amp to try and squeeze some better sound out of it (if possible)

I also read that adding an extra 10000uF-20000uF cap in parallel, between the power supply and the board will improve sound as well... can anyone confirm if this is true and if i'm correct in how it gets installed?

I will be using a Meanwell 24v PS (https://www.mouser.com/datasheet/2/260/s-350-spec-1179912.pdf)

Here is the amp in question

eZTbqQy.jpg

LOHLLSj.jpg


I will be driving a pair of TIC GS3 8ohm speakers.

Many thanks in advance for the help :up:

-Dom
 
Mainly better output filter inductors. The ones shown will saturate around 3A (peak), thus 2Arms.
Short the polarity protection diode in the middle between the inductors and put the extra decoupling capacitor(s) near the power terminals.
The ability to handle in particular bass transients depends on the charge you have ready, here stored in the decoupling capacitors.
If the power supply latches a current overload, it may not start up.
 
I was under the impression that the Meanwell power supply was more capable of handling this amp then a power brick... guess I was wrong. :eek:

Its possible the power supply wont like the extra capacitance and will go into protect mode at power up.

Is there any way around this?

Mainly better output filter inductors. The ones shown will saturate around 3A (peak), thus 2Arms.
Short the polarity protection diode in the middle between the inductors and put the extra decoupling capacitor(s) near the power terminals.
The ability to handle in particular bass transients depends on the charge you have ready, here stored in the decoupling capacitors.
If the power supply latches a current overload, it may not start up.

The output filter inductors are the four 220 Chokes on the left of the heatsink, correct? What value / type would you suggest replacing them with?

After removing the diode and bridging the pads, the decoupling cap(s) connect directly to the negative and positive input terminals? What values would you suggest and is it better to have two instead of the one?

Based on my experience with other classD amps I'd suggest extra decoupling on the analog signal rails. But you'll need to take the heatsink off to reach those pins.

I don't mind taking the heatsink off. I was planning on adding better thermal paste.

What advantage would adding extra decoupling on the signal rails provide?

Are any of the visible caps on that board for the signal rails? Would it be easier to change them out for a better quality / vaule? or is removing the heatsink to get to them necessary?
 
The output filter inductors are the four 220 Chokes on the left of the heatsink, correct? What value / type would you suggest replacing them with?

After removing the diode and bridging the pads, the decoupling cap(s) connect directly to the negative and positive input terminals? What values would you suggest and is it better to have two instead of the one?

I would replace them with better 22uH inductors, for instance of the SAGAMI 7G23A (220) type. Unfortunately, the size goes up with higher current rating so you will have to arrange them on the rear of the board. Alternatively, use toroid types of good quality.

If you bridge the polarity protection diode, the power connection terminals and external decoupling capacitor(s) are directly connected to the small on-board decoupling capacitors. The small decoupling capacitors will handle the high frequency ripple from the carrier frequency. Use one or two capacitors as it is the most practical. One 10000uF or two 4700uF.
 
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What advantage would adding extra decoupling on the signal rails provide?

Its rather conjecture because I've never played with a TDA7498 but on TDA8932 adding extra decoupling on the signal supply pin cleans up the top end no-end. Not a small difference - I considered the part as only a bass/mid amp in an active set-up prior to discovering this effect, due to the harshness of the HF. But with a cleaned-up supply its absolutely fine as a full-range.

Are any of the visible caps on that board for the signal rails? Would it be easier to change them out for a better quality / vaule? or is removing the heatsink to get to them necessary?

I doubt any visible caps go to the signal rails, the DS schematic shows just a small cap (100nF) which will most likely be hidden under the 'sink.
 
I would replace them with better 22uH inductors, for instance of the SAGAMI 7G23A (220) type. Unfortunately, the size goes up with higher current rating so you will have to arrange them on the rear of the board. Alternatively, use toroid types of good quality.

Do you know of a good source for the SAGAMI 7G23A's? Also... can you recommend a good toroid?

Its rather conjecture because I've never played with a TDA7498 but on TDA8932 adding extra decoupling on the signal supply pin cleans up the top end no-end. Not a small difference - I considered the part as only a bass/mid amp in an active set-up prior to discovering this effect, due to the harshness of the HF. But with a cleaned-up supply its absolutely fine as a full-range.

I doubt any visible caps go to the signal rails, the DS schematic shows just a small cap (100nF) which will most likely be hidden under the 'sink.

I will remove the hs and take a look. Thank you for the help.
 
Do you know of a good source for the SAGAMI 7G23A's? Also... can you recommend a good toroid?

Sorry for the late reply.
What I use is actually 7G17A inductors of the SAGAMI type. SAGAMI is a Japanese brand and I realized, difficult to find for end-users in the US.
I bought mine here: 10pcs new Digital amplifier dedicated shielded inductor 7G17A 22uH -in Replacement Parts from Consumer Electronics on Aliexpress.com | Alibaba Group
Mine are SAGAMI type only because nowhere they are marked with "SAGAMI". Mine seem to work.

But, US has got its own supply of Bourns inductors that are probably fine as well. One example from Farnell:
(linking doesn't work)
SRP1265A series

At Farnell I found chokes pretty similar to those initially installed in your board.
They indicate the saturation current to be 4A. The Asian chokes I have never seen a thorough specification for, only a hint of 3A for saturation. The Asian ones are not fully identical to the Bourns ones.

The initial inductors are SMD type and the Bourns types are for SMD. But, the Bourns inductors are larger. It is not obvious how to do the replacement on the board. Sometimes, I put the filter just outside of the amplifier board.

I only know toroid types of Asian origin. Some I have good experience with. But, they are not cheaper than Bourns chokes, and Bourns you (US) get quicker and with clear specifications.
 
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Interesting measurement/observation

I recently got around to finally wiring up some of the tpa3118 pbtl mono boards ( and a sanwu blue tda7498) ........
why they seem to be running ok sound and dc offset ( the 3118 0vdc and the 7498 ~50mv) additionally if I measure ac volts with music playing the output at each of the inductors are similar ( as much as I can measure ac with a voltmeter)
What is interesting/ confusing to me is on both board types there is one of the four ps cap and a inductor on the 7498 board that are running essentially at room temp (+-1-2c)while the other3 are 10-15c above ....same with the 3118 but just one of the ps cap.
Is this normal? Or is it sign of nonfunctional/counterfeit caps and a inductor that the actual value is so low there is little resistance?
I also posted this on one of the tda3118 threads to see if anyone there had some insight
 
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