Now I find my TDA7498 board is lack of bass and a bit harsh at treble then I will try to replace the output inductors and capacitors. Maybe it's not a miracle but as the DIYers, we will keep try and try and try... right?
True, keep on trying. My comment on the cost was to say that perhaps spending 40$ just on an output filter with very fine chokes and capacitors is perhaps a bit excessive for a board costing 12-15$. Try to find something in-between and something you can get in your area. Here I can get almost anything if I just pay the price.
Copied from TPA3116D2 Amp topic
I have found probably the same amp cheaper on taobao --> amp
By the way what voltage do you recommend for such a amp ?
I know it can be used with 36V but with THD 10%, which is probably to much, right ?
Right now I am very happy user of tpa3116 (amp which you have recommended with sanwu capacitors - probably fake ones), but I am thinking about that tda for some bigger speakers.
How much real power it can give for 8 ohm speakers ? According to taobao description 160W for 4 ohm and 36V
There is a YT from a russian guy who burned it as well; he tried really hard by playing sine waves into 4 ohm resistors; which is 10 times as much power compared to playing music with regular speakers. My guestimate is that with normal use it will be fine.
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Watched the youtube posted by baszek (again); and he is getting 2x150W @ 2.67Ohm @ 36V 1%THD as max with his dynamic burst test. (without burning it)
Does anyone know why it's bass output seems to be weak? Is this with all 7498E boards?
Does anyone know why it's bass output seems to be weak? Is this with all 7498E boards?
"Weak" is subjective. For my TDA7498E board, I notice no less bass than for my other amplifiers of good quality. Also, the low bass handling is fine with good supply line decoupling.
I know our member in the far north of Norway made a PBTL version of that board because he loves Motorhead and Lemmy's bass playing. He was very happy with the board performance.
In what way do you find the bass weak?
i dont follow this .....but here it is:
https://www.diyaudio.com/forums/class-d/323605-7498e-btl-mode-question.html#post5455744
chris
https://www.diyaudio.com/forums/class-d/323605-7498e-btl-mode-question.html#post5455744
chris
I have not noticed it, but have not listened to them much as I like my tpa3116 2.1 boards so much.
But I read it many times like in post #661 and the reviewer in the YT video also points it out.
Hi all.
I use one of those red TDA7498E board with a 300VA transformer and "stupid-me" 50000Uf supply filtering as my main system everyday and i can't say basses are weak, to me it's a flat sounding amplifier, I can't get more basses from a tpa3116 or any other non-equalized amp.
after a few hours running i soldered some more capacitors to lower the high pass filter at input but it didn't change nothing.
with stock inductors at 1st i didn't noticed any problem, it was a good mellow warm sounding board, I kept it like that for months and liked it.
with some sagami 7g17a inductors clones it became clearer at low and top end , a bit more transparent , flat and neutral, for me it's an upgrade but i don't get more basses, just better defined than before.
there is loudness , equalizer , vented and totally imbalanced speakers in to many consumer electronics products today.
when you listen to a flat system at 1st you always thing it miss something but when you take time with it you realize that there was many things you never eared before hidden in all those mud.
I use one of those red TDA7498E board with a 300VA transformer and "stupid-me" 50000Uf supply filtering as my main system everyday and i can't say basses are weak, to me it's a flat sounding amplifier, I can't get more basses from a tpa3116 or any other non-equalized amp.
after a few hours running i soldered some more capacitors to lower the high pass filter at input but it didn't change nothing.
with stock inductors at 1st i didn't noticed any problem, it was a good mellow warm sounding board, I kept it like that for months and liked it.
with some sagami 7g17a inductors clones it became clearer at low and top end , a bit more transparent , flat and neutral, for me it's an upgrade but i don't get more basses, just better defined than before.
there is loudness , equalizer , vented and totally imbalanced speakers in to many consumer electronics products today.
when you listen to a flat system at 1st you always thing it miss something but when you take time with it you realize that there was many things you never eared before hidden in all those mud.
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I have four of the red boards running at 36v. Build quality seems variable. I have one board with reversed color rca connectors. One board kept activating the fan, even when not under load, so I disconnected the fan (it really is too loud). No issues overheating. 8ohm loads, not pushing too hard.
What is the final word on running these boards PBTL? I have a 4 ohm sub I'd like to drive with a spare board I have.
I know there was talk about it in this thread, some of which certainly went over my head. My understanding is that there is no consensus about whether chokes need to be removed, and also, it doesn't seem to matter which RCA connector to use for signal in, or which connector to use for speaker out.
Benefit of running PBTL is for the amp to be able to run 4 ohm loads, rather than doubling of power available..
Am I correct about all this?
I know there was talk about it in this thread, some of which certainly went over my head. My understanding is that there is no consensus about whether chokes need to be removed, and also, it doesn't seem to matter which RCA connector to use for signal in, or which connector to use for speaker out.
Benefit of running PBTL is for the amp to be able to run 4 ohm loads, rather than doubling of power available..
Am I correct about all this?
Almost.
Consensus was for the past, now we live in societies with competition and conflict!
Sorry, I got carried away by the latest propaganda.
You should remove unused chokes because a choke with a signal may start resonating and build up a rather high voltage if not damped (by a load) and may damage components. I have a consensus with myself on this.
For that board, it does not matter which RCA input connector and corresponding output connector you use as long as you use only one. Once more consensus with myself.
PBTL leaves the same output voltage level, thus the same output power for the same load impedance. Advantage: the impedance of the output switches becomes half and the current limiter level is normally raised such that you can use a lower load impedance. Hat-trick on consensus with myself - I am brilliant!
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Your eyes are better than my memory - in PBTL mode it seems you can only use the left channel input. I checked the datasheet. I still believe you can use left or right output but not to complicate matters, use the left channel output as well.
I have to be careful not always agreeing with myself.
And the benefit it that you can run 3Ohm loads within spec instead of 4Ohm in BTL.
But Biggywizz (?) tested it on youtube and got 2x150W @2.67Ohm in burstmode, so it is pretty safe to use it at 2Ohm in PBTL and get 200+W out of it.
When asked to play sinewaves at full power into resitors, the chip seems to have heating/burning issues, but should be fine with music into speakers.
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It is still unclear to me as the blue Feixiang board does it differently and the 7498E datasheet says:
"5.1") Stereo and mono BTL operation selection using the MODE pin:
The TDA7498E can be used in stereo applications or mono BTL applications. Connecting the MODE pin to the VDDS pin configures the device in mono BTL. The output of the two channels can be paralleled.
When the MODE pin is connected to ground or floating (pulled down internally) the device works as a stereo amplifier."
Which implies that there is no PBTL mode, just mono (1 input) BTL with 2 outputs, which can be paralleled at the outputs/ speaker connectors.
It is still unclear to me as the blue Feixiang board does it differently and the 7498E datasheet says:
"5.1") Stereo and mono BTL operation selection using the MODE pin:
The TDA7498E can be used in stereo applications or mono BTL applications. Connecting the MODE pin to the VDDS pin configures the device in mono BTL. The output of the two channels can be paralleled.
When the MODE pin is connected to ground or floating (pulled down internally) the device works as a stereo amplifier."
Which implies that there is no PBTL mode, just mono (1 input) BTL with 2 outputs, which can be paralleled at the outputs/ speaker connectors.
True, some ambiguity.
Figure 3 of the datasheet shows connection directly at the output of the TDA7498E chip. Seen in this context and on chip level, the statement "the output of the two channels can be paralleled" is valid in the sense that they are the two channels inside the chip. This configuration is what we call PBTL as the switches of two channels work directly in parallel before the filter.
If the switches are logically coupled to switch alike but actually not connected directly before the filter, the average voltage at the two outputs are at any moment alike and it should be possible to connect the two channels at the output of the filters. In such case, the inductances act in parallel with half the individual inductance and the capacitance with the sum of the two capacitances. Thus, the filter becomes more "heavy" to pull with higher circulating current. Such a more heavy output filter is typically used when the speaker impedance is lowered (2 Ohm). But, if the load is maintained at what one stereo channel can pull, I would use only one filter and traditional PBTL. Then, the chip losses are less from the PBTL coupling.
Fijne zondag.
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Sorry for the late reply. Yes PBTL encompass combining both channels at some point. While BTL is well defined technically, PBTL is rather a concept made up by manufacturers and designers and lack a unique definition. Combining before or after the filter? - "that is the question" (Shakespeare - Hamlet).
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