TI TPA3255EVM

Jump to Latest
#543
Nanoloop said:
Both measured performance and subjective sound quality are worse using single ended than using BTL. I bi amp using a modified DBX234XL (discontinued so they are US$20 on Taobao) and 2 stereo BTL amps.

Everything you could want to know about bi-amping including schematics and parts calculator is Here thanks to Rod Elliott.
Click to expand...
do you have any links showing SE mode is worse than BTL? never read that anywhere, ive configured mine as 2.1, with two SE channels running a fullrange driver each, with a gentle lowpass on one, before amp.

rather than a btl channel driving two drivers.. this was decided since the power output matches the drivers better in se mode, and the impedance of the drivers matches the amp better.
 
#544
ccss said:
when playing through the subs and noticing distortion, is the CLIP indicator lit or blinking? also, what resistance are the subs?
you did an amazing job getting everything in that case!
also great job on the cooling solution...how is that working?
Click to expand...


Hi , no clip indicator lit.. ive got everything crossed that the amp is fine and the nastiness i can hear is due to caseless drivers. hardly an ideal setup to test SQ of an amp.. ill just have to wait.


thanks for the compliment, yeah it was a REAL challenge fitting everything in, much harder than initially anticipated. in the 3d model it all slotted in very comfortably with nice spaces around each element. when i actually came to put it together , i noticed all the things i had not considered in my model.. practically every component in the amp had to be modified in some way to fit. its taken the best part of 4 months (just a little every evening after kid is sleeping, and taking it v slow so i didnt have to undo too many mistakes) but now, assuming this distortion thing isnt a thing, im very happy with the result. amp is quiet, and tiny, and very powerful. bluetooth has incredible range with antenna mod, frontpanel minidsp control hack works perfectly..


wrt the cooling. it -seems- to work, but ive not had proper speakers to crank it with, so ive not done a stress test yet.

im not worried about the amps, they have= big heatsink and 4x 60w heatpipes to shift the heat.. before installing i put a small blowtorch to the "hot" end of the cooling system, and after 5 mins, heatsink was hot, but i could still basically touch the "hot" end.. so that seems positive.

the psu is a bit more of a question mark.. at the mo all the power semiconductors are connected to case wall via a single 60w heatpipe, but i also have another 70w flatpipe which connects same block to case lid when all is proven working.. however ive noticed that the smps transformer gets quite hot, after an hour of running at (very) low volume, the trafo is up to about 50 degrees.. if that increases drastically under load i might have a problem and be forced to consider a fan.. which is another thing to squeeze in!!
 
#545
robinlawrie said:
do you have any links showing SE mode is worse than BTL? never read that anywhere, ive configured mine as 2.1, with two SE channels running a fullrange driver each, with a gentle lowpass on one, before amp.

rather than a btl channel driving two drivers.. this was decided since the power output matches the drivers better in se mode, and the impedance of the drivers matches the amp better.
Click to expand...

The measured performance is in the TI datasheets and it also stands to logic (higher effective power, lower output impedance, etc) so tbh it shouldn't be a surprise. The SE topology on most class D amps shows they will be worse because SE usually has to have AC coupling / DC blocking caps - 470uF electrolytic iirc for TI TPA325x - in the signal path when BTL doesn't.

I have a 2.1 fda amp and an exact same model with 2.0. The 2.0 definitely sounds better but the 2.1 is still fine for its purpose where 2.1 is needed.
 
Last edited:
#546
ok well i wish someone had pointed that out to me during the lengthy discussions i had here about the best configuration for my amp 😛

ahh well since i can get (according to the datasheet) 77w @4 ohms with 1%thd, (more than my speakers can handle) and i doubt if i can hear the difference between 100db snr and 112 db snr, probably i shouldnt worry too much .
 
#549
#551
new TPA3255EVM user

Hi All,

Ordered the TPA3255EVM board together with a Mean Well USP-350-48 (350W Single Output with PFC Function, no fan).

This Mean Well USP-350-48 has no screw down terminals, ( I did not notice ) so I need to order:

2 x Buchsenleiste (Standard) VH Polzahl Gesamt 7 JST VHR-7N Rastermass: 3.96 mm 1 St. kaufen

1 x Buchsenleiste (Standard) VH Polzahl Gesamt 5 JST VHR-5N Rastermass: 3.96 mm 1 St. kaufen

3 x Buchsenkontakt VH Polzahl Gesamt 1 JST BVH-41T-P1.1 1 St. kaufen

Put together today and was surprised that I had no sound from the right channel, no wonder because Page 3 of the User documentation for the TPA3255EVM states:
"The input RCA jack, J3, is used to provide INA inputs and RCA jack J14 is used to provide INB inputs. RCA jack J18 is used to provide INC inputs and RCA jack J15 is used to provide IND inputs with differential inputs.".

Luckily the 2.1 schema on page 5 shows the right configuration, to get the right channel working from my iPhone so I used J3 and J18 for single ended inputs.

Mentioned before, but repeating here boards dimensions are 160 x 120 mm and not 140 x 120 mm as stated on page 12.
The actual height of the evaluation kit is 78 mm, (Measured bottom of the standoffs on the table up to the top of the heatsink).

For the first listening form the pod I have no complaints.

See picture of the setup.

Happy listening
Grtz

Bert
 

Attachments

  • IMG_20180218_124338170.jpg
    IMG_20180218_124338170.jpg
    762.2 KB · Views: 467
#552
Too much and a good match

One more time today,

This amp "TPA3255EVM" is too much for my old test speaker the small JBL Northridge E 20.

But a perfect match for my KEF LS50 speakers, with the "I pod" playing I can not tell about the full spectrum, but the "I pod", TPA3255EVM and the LS50 are a very nice trio for long listening sessions.

Hopefully, next week I will connect the DDDAC-1794, and check that combo.

Until then happy listening too all.

Grtz

Bert
 
#555
Yes, I do have turn-on/off thumbs.

I use the reset button on the EVM to "prevent" the turn-on turn-of thumbs

I set the button to reset mode before power-on, when I hear the click on the mean well PSU and the green led on the EVM board are on, I set the reset switch to the normal position. On power-off I do the reverse.

Grtz
Bert
 
#559
With my efficient DIY horn-loaded speakers the turn on “thump” is more of a click.

I struggled with what to do about the reset button after putting the EVM and Meanwell in a case. Rather than relocating the reset to the exterior, I leave it at “normal” and control line voltage to the Meanwell from the on/off switch on the case.

I use one of two Pono players in lieu of a pre-amp. I always turn on the Pono player first before powering the Meanwell, and the reverse at shut down. The noise heard from the speakers is negligible.

FWIW, at idle between tracks on songs, there is NO hum from the very efficient speakers. With any tube amp I ever used, there was always a slight hum under those conditions.
 
#560
Thanks Bert, planning to put this in a DIY case and I want to know if I need to make a hole in the enclosure panel where the reset button is so I can toggle the switch during turn on.

watchtmouse said:
Yes, I do have turn-on/off thumbs.

I use the reset button on the EVM to "prevent" the turn-on turn-of thumbs

I set the button to reset mode before power-on, when I hear the click on the mean well PSU and the green led on the EVM board are on, I set the reset switch to the normal position. On power-off I do the reverse.

Grtz
Bert
Click to expand...


Hi DizRotus, how did you control the line voltage to the Meanwell psu. Sorry I'm very green on this topic and honestly this is gonna be my first amplifier project 😀

If you can post a picture of the internal of your amp, I would really appreciate it.

Thanks and regards,
Anton


DizRotus said:
With my efficient DIY horn-loaded speakers the turn on “thump” is more of a click.

I struggled with what to do about the reset button after putting the EVM and Meanwell in a case. Rather than relocating the reset to the exterior, I leave it at “normal” and control line voltage to the Meanwell from the on/off switch on the case.

I use one of two Pono players in lieu of a pre-amp. I always turn on the Pono player first before powering the Meanwell, and the reverse at shut down. The noise heard from the speakers is negligible.

FWIW, at idle between tracks on songs, there is NO hum from the very efficient speakers. With any tube amp I ever used, there was always a slight hum under those conditions.
Click to expand...
 
You must log in or register to reply here.
Top Bottom