I'm in no way picking on you chermann, but this "300W is to weak" meme that's floating around here is daft.
To weak for what? To weak for two channels max output in a simulation - yes.
To weak for playing two channels 1 kHz sine wave max output in a resistive load - yes.
To play two channel music at ear-splitting levels, no way!
I agree.
It's crazy to me that 300W would not be enough power for someone listening in a living room.
Just curious about our comment " ....the lrs 350-48 is too weak to push an 8 ohms speaker...". Was this your personal experience, or you read it somewhere. I think the impedance is less important as compare to the sensitivity when it comes to high sound pressure level.
I have used the 3255 with the lrs 350-48 to drive two pairs of floor standing speakers. Both have a nominal impedance of 8 ohm. One has a sensitivity of 87 db, the other 84 db (pretty insensitive). I can rock the house easily with either pair of speaker, even the low sensitivity one. In addition, quite a few people have reported that even playing loud (using a 3255) for a long period of time, the cooling fan in the lrs 350-48 did not turn on because the PSU never really got hot. I have verified that myself - the lrs 350-48 barely got warm even when I cranked the amp up and played for a relatively long time.
In my personal experience, the lrs 350-48 does not have any problem supplying the power needed by the 3255 to drive a 8 ohm speaker to loud sound level.
Regards,
depends on the speakers, mine is 92dm*m/w and 100W is crazy loud power to me but for 84db*m/w it is not enough for sure. Double power is only +3db in SPL, hence "deaf" 84db*m/w speakers need 630W to get the same SPL as 92db speakers produce at 100W.
Hi guys
sorry to intepret my thinking to this expert thread: (in my mind is still my 4 ohms Speakers..)
here is the first AHa effect for me:
https://www.diyaudio.com/forums/class-d/87913-class-amp-photo-gallery-132.html#post5405118
thanks ivx
read on
here i start to check the PSU and i got some nice Information about power.
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-33.html#post5526721
the lrs-350-48 has an maximum current of 7,3Amps for both channels ! =
3,65 Amperes per channel => I^2 *R = 3,65 ^2 * 8 = 106Watt
its enough for listening at home but with speakers lower 86 db and a big room just nice 😉
my lessons learnt is that the LRS is stable but at lower impedances the hick up is starting.
so you do not have 350 WATT i real.
chris
sorry to intepret my thinking to this expert thread: (in my mind is still my 4 ohms Speakers..)
here is the first AHa effect for me:
https://www.diyaudio.com/forums/class-d/87913-class-amp-photo-gallery-132.html#post5405118
thanks ivx
read on
here i start to check the PSU and i got some nice Information about power.
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-33.html#post5526721
the lrs-350-48 has an maximum current of 7,3Amps for both channels ! =
3,65 Amperes per channel => I^2 *R = 3,65 ^2 * 8 = 106Watt
its enough for listening at home but with speakers lower 86 db and a big room just nice 😉
my lessons learnt is that the LRS is stable but at lower impedances the hick up is starting.
so you do not have 350 WATT i real.
chris
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I don't think it works like that.
Imagine you only have one speaker. By your logic that one speaker would use 7.3^2*8=426W!! Impossible with a 350W PSU.
I don't know how it works, but I don't think it's like that. 🙂
jop...thats the reason why i am testing the psu...open the pdf. its under the pics
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-33.html#post5526721
as you can see the voltags sags and the power is not as recommended
chris
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-33.html#post5526721
as you can see the voltags sags and the power is not as recommended
chris
earsofgold, he talking about the clipping which could be by voltage and by the current(i.e. voltage drops) as well.
no. with static resistive load directly on the output terminals.
i have no idea how to test a psu with sinus load.
I've got a question, if tpa3255 has >65dB PSRR, and meanwell lrs-350-48 has 200mV ripple and noise, how do I calculate how much ripple will show up on the output?
+1
And don't forget power compression, it probably will be over 1000W for the 84dB/W speaker.
Great article: PA Systems
"1 - The Myth of Power Handling Let's look at a simple example. Two systems are set up side-by-side. One has an overall sensitivity of 100dB/W/m, meaning that an input of 1W will give an SPL (sound pressure level) of 100dB at 1 metre distance. Power rating is 100W maximum continuous average for this first example.
The second system is rated at 90dB/W/m sensitivity, but has a power rating of 1,000W - also continuous average. The question is ... which will be louder?"
Any thoughts about a Meanwell SDR 480-48 power supply for the TPA3255EVM? Its spec sheet says its capable of 720W for up to 3 seconds, rated power is 480W @ 10A, peak current is 15A. I'm driving two 8 Ohm speakers (one per channel).
Looks a cheap way into 10A. Lower ripple and noise than the other usual form factors usually mentioned here.
Not sure if it needs the relay signal switched to operate it.
Not sure if it needs the relay signal switched to operate it.
Ohh, PA world isn't honest at all, they pretend sale "8ohm drivers" with actual Rdc around 2ohm. How else to report annually about the progress if no new ideas, no new materials? Only cheating with so-called "1W" sensitivity, which actually a voltage 2.828VRMS at 2ohm )) Worldwide more and more popular modus operandi is a lie, I really worry about the future of that planet.
There is not much you can calculate, because
-PSSR is specified normally at 1khz. It may degrade towards higher frequencies
-ripple is measured with an oscilloscope with a bandwith that far exceeds the audio band.
The ripple content normally is above the audio frequency band.
So this is no information useful to calculate the audible contribution of smps ripple to your audio output.
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@earsofgold - added to what @voltwide has said above, if you look carefully at the PSRR 'headline' number you'll see its quoted as 'No input signal'. Which is precisely uninteresting as you'll presumably be wanting to apply one in order to listen to music.
No relay switching necessary. The Meanwell power supply simply provides the relay to connect to an external LED or whatever as a DC power status check ok. Worst thing about this PS is the DIN rail mount. I have it mounted on it's side in a very well ventilated metal chassis that also mounts the TPA3255EVM. Pretty good setup in a 2U rack mount chassis that has plenty of room for other small items like a USB jack to power a streaming audio source.
So far, everything sounds good, and it can get quite loud, though I can't max it out as my speakers are rated at 250W.
I have a question. Is it possible with the TPA3251 (and others in the same chip familly) to adjust the gain, in order to reduce it ? The intention would be to build a sort of power buffer to be plugged after different input stage to do some experiment, in the spirit of M2X – diyAudio Store.
Or of the pass B1 Korg triode (or pMillet equivalent) preamp. The gain of the B1 Korg triode preamp is 17dB. So the gain of the power stage should be lowered.
Is it possible ? Would Sound Quality be lost in the process ?
Best regards,
JMF
Or of the pass B1 Korg triode (or pMillet equivalent) preamp. The gain of the B1 Korg triode preamp is 17dB. So the gain of the power stage should be lowered.
Is it possible ? Would Sound Quality be lost in the process ?
Best regards,
JMF
In the datasheets it lists the gain as 21.5dB for the TPA3255 and 20dB for the TPA3251.
That would imply to me that it is not possible to change it.
That would imply to me that it is not possible to change it.