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Class D Switching Power Amplifiers and Power D/A conversion

TPA3255 - all about DIY, Discussion, Design etc.
TPA3255 - all about DIY, Discussion, Design etc.
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Old 21st October 2019, 09:05 PM   #1451
eX Radikal is offline eX Radikal  Portugal
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After testing the sub with my Blaupunkt GTA 2 Special MK II which reaches 180w at 4ohm bridged and not even getting it at max volume, I'm sure I'll not get to the limits of the TPA3255 neither.
With that in mind, can you recomend something more cheap or still the 3E boards? I'll chech those prices now.
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Old 22nd October 2019, 08:01 AM   #1452
vacuphile is offline vacuphile  Netherlands
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Quote:
Originally Posted by xrk971 View Post
Some helpful diagrams from Maxim here. I think it is important to have a floating scope, otherwise the true 2x Vdd cannot be visualized:

Click the image to open in full size.

Click the image to open in full size.
I think you misinterpret figure 5. and 6., but there also seems to be an error in it. In Fig. 6., at OUT-, it should have shown the distance between GND and -Vdd. It is a dual supply situation that is depicted, but with an error as mentioned.

Question authority, think for yourself.

In a single supply setup, there is no -Vdd, there is nothing to generate a -Vdd, so the potential between two output terminals can never be 2xVdd. The minimum of each output is ground, the maximum Vdd. the maximum potential the difference between the two.

Another way of looking at it is by showing that this doubling of Vdd would lead to impossible results: suppose a bridged TPA3255 running on a single 50V supply could deliver twice that voltage between its output terminals. A 4 Ohm load would than draw 25 Amps for 2500 Watts of output.....
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Old 22nd October 2019, 08:21 AM   #1453
voltwide is offline voltwide  Ireland
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I do not get your point.

Output power is P=Vpē/2R equivalent to P=Vppē/8R
With Vpp=100V and R=4Ohms this results in 312W rms.
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Old 22nd October 2019, 08:45 AM   #1454
FauxFrench is offline FauxFrench  France
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@vacuphile,
Nobody states that you have an instantaneous voltage of 96V across the load. It remains 48V as the instantaneous peak voltage. What was stated was that the output signal is up to 96V peak-to-peak which is concluded by comparing two instantaneous voltages at different moments in time.
Think of it as an ordinary SE-coupled amplifier with +/-48V supply and you have the same result.
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Old 22nd October 2019, 08:49 AM   #1455
vacuphile is offline vacuphile  Netherlands
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100 V between two terminals and a 4 Ohm load draws 25 Amps, times 100 is 2.5kW. Note: this is peak, not RMS value, multiply by .7 to get there.

Peak to peak is not really relevant for power draw, it is the maximum potential between the two output terminals you have to look at. Your example appears for a ground referenced half bridge amp.
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Old 22nd October 2019, 08:50 AM   #1456
vacuphile is offline vacuphile  Netherlands
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Quote:
Originally Posted by FauxFrench View Post
@vacuphile,
Nobody states that you have an instantaneous voltage of 96V across the load. It remains 48V as the instantaneous peak voltage. What was stated was that the output signal is up to 96V peak-to-peak which is concluded by comparing two instantaneous voltages at different moments in time.
Think of it as an ordinary SE-coupled amplifier with +/-48V supply and you have the same result.
Yes, that is what I have been arguing all along. Is my language not clear enough?

Edit: or did you just barge into this discussion without having read what came before?
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Old 28th October 2019, 02:46 AM   #1457
cacao ambiance is offline cacao ambiance  United Kingdom
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a new duel mode finished amp.
  • its a mono amp with a option for low pass bass freqs for subwoofer or bybass lowpass filter and be a full range mono amp.
  • with a line-level sub-out rca to send low pass sub filtered signal to a active sub/other amp for sub.

Snag is its limited to 300w despite being mono. 35v power input limit.
I want a amp like this but full power 8-4ohm 600w , 48v dc power input!

AIYIMA TPA3255D2 Amplifier 300W HIFI Mono Channel Audio Power Subwoofer Amplifier Class D AMP NE5532 OP AMP For Home Sound Audio-in Amplifier from Consumer Electronics on AliExpress - 11.11_Double 11_Singles' Day
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Old 2nd November 2019, 01:36 AM   #1460
jack_b is offline jack_b  United States
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TPA3255 - all about DIY, Discussion, Design etc.
I have a question about 3e Audio boards. I've ordered the TPA3255 amp board and the matching 48V power supply, and expect delivery in a few weeks. I'm assembling other parts for the amp, including standoffs. Can anyone tell me the diameter of the holes on these boards for the standoffs? I've emailed 3e Audio without getting any response. I'm guessing about 3mm, but I'd like to know before ordering parts.
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