Ebay cheap TDA7498 boards

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Hi I have a tda7498e amp for aliexpress and it works fine but it doesn´t support all of his potencial. I explain: i put 36v with a power supply and it gives plenty of volume but only for 10 seconds, then it goes to a down volumen.
Is this your case? What can it be?
Thanks.
Do you recomend me a powerfull dc amp?
 
This one may be easy, I would suggest. Take of the heatsink and look which Chip you got. A 7498 will shut down if overloaded, with a 4 Ohm loudspeaker and 36 Volt. Only the "e" version can run 36 Volt and less than 8 Ohm. So most probably there is the problem. To test it, take a 8 Ohm speaker or two of 4 Ohm in series and try again. Another test would be to use only 24 Volts.
You are sure your 36 Volt DC are well regulated? Not like a 36 Volt AC transformer?
 
Hi I have a tda7498e amp for aliexpress and it works fine but it doesn´t support all of his potencial. I explain: i put 36v with a power supply and it gives plenty of volume but only for 10 seconds, then it goes to a down volumen.
Is this your case? What can it be?
Thanks.
Do you recomend me a powerfull dc amp?


You write "then it goes to a down volumen". I understand it such that it plays loud for a start but after some 10 seconds the volume is reduced and it continues playing but at a lower volume (it is not turned off). Correct?
If so, it seems the voltage at the gain pin (30) is not constant but varies after start-up. The gain setting is described in section 5.2 of the datasheet. If that gain-setting voltage varies, it could be because an SMD capacitor has been mounted instead of a resistor.
 
If i decide to use a preamp with this amp for getting more power will it work?
And if this works what voltage is the maximun for the imput of the tda7498?

Thanks.


Hi

no a preamp doesnt help...normally with input voltage about 100--->300mVrms its really loud at home
As FF wrote. the gain setting is for us unknown, which chip is really inside...make a photo-then we can decide the max voltage for the power supply....
so therefore the input max. voltage is not possible to write to you.


chris
 

ICG

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If i decide to use a preamp with this amp for getting more power will it work?
And if this works what voltage is the maximun for the imput of the tda7498?

If the amp is still not clipping and the input isn't overdriven, and the power supply doesn't sag, it might increase the output until one of these points are fulfilled. However, it only got its maximum power of 160W per ch. only at 4 Ohm or bridged the 220W at 3 Ohm (at 10% THD). On 8 Ohm stereo it's the half (2x 80W), on bridged (BTL) it's still just 80W.

If the amp stops playing after a few seconds, then it's either the power supply switching off (because of overload) or the amp gets too hot (heatsink not properly mounted) or the over current protection triggers.
 


nice little amp. you can set the gain to a moderate gain. the red box with the 2 white small switches should set the gain. (page 9 of the datasheet...in the table closed loop gain= about 24dB- 37dB)

as icg correctly wrote: your amp should not be driven with 4 ohm impedance speakers per channel. with 34V on 8R or 36V on 6R maximum!!

after the amp stops playing after a few seconds - is after cooling phase the amp ok?...so if the amp is cool enough you can reproduce this event?




chris
 
nice little amp. you can set the gain to a moderate gain. the red box with the 2 white small switches should set the gain. (page 9 of the datasheet...in the table closed loop gain= about 24dB- 37dB)

as icg correctly wrote: your amp should not be driven with 4 ohm impedance speakers per channel. with 34V on 8R or 36V on 6R maximum!!

after the amp stops playing after a few seconds - is after cooling phase the amp ok?...so if the amp is cool enough you can reproduce this event?




chris

My first messages were about a tda7498e that explode Two weeks ago. Now i have the amp of the link. It works fine, my only concerns were if i need or have to use a preamp and max voltaje.

Thank you very much for your time.
 
Hi!

I'm a noob in this matter, and learned a lot after passing a couple hours reading this post.

I'm a simracer and i'm building a system to myself with tactile immersion, i use 2 transducers (subwoofers) that have 100W 4ohm each.

1rst i bought this amp:

hifi 2.0 tpa3116d2 placa estereofonica do amplificador de dois canais do amplificador audio de dois x 50w digitas Venda - Banggood.com

The chip melt down after 10min of use at 30% +- of power.

Them i bought this:

CIRMECH Digital Amplificador de Potencia De Audio Amplificador de Audio Conselho TDA7498 2.0 Amplificadores Classe D amplificador Estereo de ALTA FIDELIDADE DC12 36V 2*100 W-in Amplificador from Aparelhos eletronicos on Aliexpress.com | Alibaba Group

The amp. came with a problem and one of the channel's doesnt work proper (plays very very low). The other channel works good, i assembled the transducers im parallel, so for now work at 8ohm and the amp doesn't get to much warm (40º +-).

But i need to build a 2 channel or even a 4 channel system, so what board you advise me to buy? It should be one with a good bass
 
Sorry my mistake, i mean in series

Good so. The 30% power is only correct if you have a steady signal (such as a sine-wave) and you have measured the output voltage. 30% of the rotation on the volume potentiometer tells very little. The output power depends on the level of the input signal and the gain in the amplifier.

I am surprised if it really melted down. The temperature protection of the chip should have shut it down before destruction.

Even if one channel only plays at low volume, the chip is likely (still) to be OK. When the chip really starts being defect, the sound tends to disappear completely.

NB: If you have put your two transducers in series on one channel, the other channel may be unloaded. That can harm the channel without load, even without an input signal. Class D amplifiers should be loaded on all channels when active.

TPA3116 in PBTL coupling (mono boards), TDA7498E or TPA3255 are good candidates.
 
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thank you for the advice!



I dont know what you mean about "steady signal" but in these simracing programs for tactile immersion you have tweak a lot to put the subwoofer only work whem it should, so as default it work all the time, in less than 10 min continuous it melt.
It was fed by a power supply brick 24V and soundcard from the PC

The other amp i don't have the knowledge to fixed, for now, work with only 1 channel until i buy a new board.

I was already inclined for two or four mono TPA3116, i read somewere that the TDA7498E doesn't have great bass its true? the TPA3255 it cost a bit more that i want to spend but if it's worth it I make the effort
 
thank you for the advice!



I dont know what you mean about "steady signal" but in these simracing programs for tactile immersion you have tweak a lot to put the subwoofer only work whem it should, so as default it work all the time, in less than 10 min continuous it melt.
It was fed by a power supply brick 24V and soundcard from the PC

The other amp i don't have the knowledge to fixed, for now, work with only 1 channel until i buy a new board.

I was already inclined for two or four mono TPA3116, i read somewere that the TDA7498E doesn't have great bass its true? the TPA3255 it cost a bit more that i want to spend but if it's worth it I make the effort

That chip is definitely melted and has ruined the PCB tracks too. No chance of repair.

Sorry, I am a simracing "noob". You may have repeated signals for simracing. My point is that with music you cannot say you used 30% of the power because the intensity of music changes importantly all the time.

We have a forum member who loves "Motörhead". Lemmy's bass on a TDA7498E should sound just great. So, not all agree it is no bass talent. TPA3255 is known to have very good bass.
But, it is all subjective.

Be careful with the heat outside!
 
Hi,

I noticed that there are two slightly different 2x160W boards with TDA7498E, the red one (e.g., https://www.ebay.de/itm/TDA7498E-160W-160W-Two-Channel-Audio-Stereo-Power-Amplifier-Board-Module-New/283493849658?hash=item42018cda3a:g:IfcAAOSwDlNc5mPU) and the black one (TDA7498E High Power Digital Power Amplifier Board 2.0 HIFI Stereo 160W*2 LH | eBay).

The layouts seem to be very similar, also the price. I only noticed different terminals, different capacitors, and that the black one has a better documentation including pictures describing the jumpers etc. Are there any known differences between these two boards, or do you experts see important differences? Which one would you prefer?

Best regards,
Crest
 
Hi,

I noticed that there are two slightly different 2x160W boards with TDA7498E, the red one (e.g., https://www.ebay.de/itm/TDA7498E-160W-160W-Two-Channel-Audio-Stereo-Power-Amplifier-Board-Module-New/283493849658?hash=item42018cda3a:g:IfcAAOSwDlNc5mPU) and the black one (TDA7498E High Power Digital Power Amplifier Board 2.0 HIFI Stereo 160W*2 LH | eBay).

The layouts seem to be very similar, also the price. I only noticed different terminals, different capacitors, and that the black one has a better documentation including pictures describing the jumpers etc. Are there any known differences between these two boards, or do you experts see important differences? Which one would you prefer?

Best regards,
Crest


Hi Crest,
I see no obvious advantages of any of the boards. I have the red board and it works. I appreciate the terminal blocks of that board.
Without knowing the black board and only judging from the photo, I have a slight preference for the black board. Better aesthetics and slightly thicker choke-wire it seems. The green terminal block should be OK. Jumpers for gain setting OK.
My very subjective impression.
 
Hi,

I received the black board a few days ago. looks good, but I couldn't try it out yet.

At the moment I try to understand the mute/standby function. Unfortunately, the datasheet of the 7498E doesn't say much about it. However, the datasheet of the 7498 includes more details, e.g., that the input current of STBY & MUTE should be less than 200µA. Is it ok to assume that both work similar in this context?

The standby and mute circuits of both datasheets (E and non-E) look very similar, but the circuit for the 7498E includes an additional resistor R19 with 33k. I don't understand why it is needed. Can somebody help? Is R4 >> than R2 to ensure that the chip is first enabled and then unmuted if both PINs are set to high at the same time?

I found another standby/mute circuit in the datasheet of the TDA7293 (Figure 6) that needs only one connector. It uses two resistors and a diode to ensure that the mute is first set to low if both PINs are connected to ground. Would it be possible to use a similar circuit for the 7498E to be able to control standby and mute with only one input? E.g., by splitting R4 into 20k and 100k and shortening the 100k by a diode?


Best regards,
Crest
 
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