me too, and bi-amping really is magic - lower IMD is a clarity revelation .@nanoloop, reading ESP is the reason I even know about bi-amping
I guess using the EVM in SE mode isn't the way to go, then. Thanks.
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.
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!!
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.
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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 .
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 .
Got some answers here (if this also concerns you):
http://www.diyaudio.com/forums/class-d/298796-electronics-aa-ab32313-2x400-32.html#post5343520
http://www.diyaudio.com/forums/class-d/298796-electronics-aa-ab32313-2x400-32.html#post5343820
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
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
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
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
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
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
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.
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.
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.
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
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