Certainly seems like it, the User Guide for the EVM board is available for everyone, just read it, filled to the brim with useful information.
http://www.ti.com/lit/ug/slou441/slou441.pdf
edit:
I am considering running the boards in SE mode (just to make a simple boombox to have on the porch), but I have not decided yet, it's very easy to change your mind, just a few jumpers to move and reconnecting the speaker wires.
http://www.ti.com/lit/ug/slou441/slou441.pdf
edit:
I am considering running the boards in SE mode (just to make a simple boombox to have on the porch), but I have not decided yet, it's very easy to change your mind, just a few jumpers to move and reconnecting the speaker wires.
Last edited:
I just bought a 3e tpa3255 board cause I really couldn't find any negatives on the forum on this one yet, so it might be good 🙂. I hope to use it with input transformers and a huge unregulated powersupply). Too bad it comes with the slow boat from china..
Wow! I don't think so fast shipping to Norway isn't even theoretically possible^^. Have you noticed any misbehavior on your 3e card? I too have musical tube amp which has a very unique sound, but the tubes are becoming quite expensive. I find that a well constructed class D amp doesn't add anything to the music as some amps do. I also have several 3116/tpa3118 wiener cards which sounds great but I'm after more power 😉
I am glad I bought the TI EVM...otherwise I would have gone back to my 3116 boards...
For me, in my system, with my music the yuan jing and 3e-audio boards sounded just fine, but not very envolving...
For me, in my system, with my music the yuan jing and 3e-audio boards sounded just fine, but not very envolving...
I'm going to try some line in transformers instead of input caps to add some "flare" to the music to make it interesting. If they have used to small input caps that will be fixed by using the transformers instead. Have you got any equipment to measure the size of the input caps on the boards? It could also be that the power caps on the the cheaper boards have to high ESR so the bass becomes weak. Do you think the 3e boards lacks bass or sounds compressed? Or is something else wrong with the sound?
i have question for tpa3255evm users. Is there a knock in the speakers, when do we start and off the amplifier?
ditto...i get a tick at power on and a louder thump at power off.
both can be avoided by using the RESET switch.
RESET puts the amp into a kind of standby mode that uses less than 2W
both can be avoided by using the RESET switch.
RESET puts the amp into a kind of standby mode that uses less than 2W
The caps ESR won't have any (hearable) impact on bass response except you listen to square bursts. Otherwise the transients of a normal bass note are to soft/flat. With this low capacitance they won't support at all. Beside that, the "ESR" at these low frequencies is several ohms, even for ultralow-ESR caps.
With plenty of headroom due to high voltage supply you won't run out of "attack" for almost all listening volumes below slightest clipping. If the clipping indicator won't come on, everything is fine as this indictor starts to commit way before clipping.
Ok thats good to know! I'm going to drive this with an diy unregulated power supply and how much capacitance do you think I need? I wan't to be able to run the amp close to clipping with the psu not causing hearable sound degradation. At which ripple voltage do you think it becomes hearable with this amp? I have 2 oil filled 63V 180 000uF caps (got them cheap) which is going into the psu. I hope this is proper overkill since the transformer is large but of poor quality so it might not deliver clean power into the cap bank. Do I need an PI filter with so much capacitance?
Clipping is a function of supply voltage, so the question for ripple voltage can't be answered.
What SPL do you need, whats the impedance of your speakers, whats the frequency of interest?
(An SMPS would be the smaller solution)
What SPL do you need, whats the impedance of your speakers, whats the frequency of interest?
(An SMPS would be the smaller solution)
What I mean is that I wan't to run the amp at full volume at 4ohms whitout being able to hear 100Hz hum. How much capacitance do I need for that? Supply voltage is 48V. I'm building this amp to last many years to therefore I prefer an unregulated psu. I usally use SMPS for short term projects. The numbers doesn't have to be excact, just ball park it 🙂
That's an advantage of an smps, there's no 100Hz hum. The PSRR is about 60dB and BTL usually cancels out ripple very good.
I'll check for some calculations.
I'll check for some calculations.
to give some kind of an answer to your question i made this quick simulation rig.
You put in some numbers from your supply and a desired load current and this gives out the 100hz hum in decibels. At room listening levels you wont need a cap at all due to the 2x4700uF on the EVM. At higher levels your SPL is mainly limited from the winding resistance of your transformer and the connection/wire resistance from supply to amp as the supply voltage sags. Like i.e. with 20A load current it is:
No more than 4x10000uF is needed here with 20A load current. 100Hz hum would be at 16dB or 420uVrms, a very calm room is at 20-30dB alone.
20A is something like 2x10A (2xBTL) -> for RMS this is 5Arms per channel or approx: 5A*5A*4R = 100Wrms per channel. Our PVDD rail is sagged to 37V due to connection resistance, winding resistance etc. Will 100W fit without clipping?
Totally simplified calculation: SQRT(4R*100W)*1.41 = 28.2V -> okay no clipping.
100W from a 90dB/W/m speaker is 110dB SPL. With 16dB 100Hz hum, the SNR calculates to 110dB - 16dB = 94dB. I guess, you wont hear any hum. 😀
Attachments
Last edited:
Edit:
One fact which is not modeled here is that you'll get sideband modulation from the hum by multipling it with your audio signal.
One fact which is not modeled here is that you'll get sideband modulation from the hum by multipling it with your audio signal.
Wow! A ton of great info, thanks! I really hope that the rail voltage doesn't sag that much from that big'ol trafo I got 😉
Good morning
I appreciate your post very much. Although a lot of it goes over my head, the above portion of what you said, I understand very well.
😁
I suppose, it explains why my simple unregulated Power Supply (mentioned in the EVM thread) is adequate for my amp.