Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

TI TPA3255EVM
TI TPA3255EVM
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th July 2018, 05:31 AM   #811
DPH is online now DPH  United States
diyAudio Member
 
Join Date: Dec 2008
Location: Portland, OR
Looks fine to me. FWIW the LRS350-48 also is dual voltage with a switch on the side. That said, it's not self contained like this unit.

The stepped voltage levels is not a feature you'll want/need, but no harm leaving it at full voltage.
__________________
Happy DIYing, Daniel
  Reply With Quote
Old 20th July 2018, 06:29 AM   #812
chermann is offline chermann  Austria
diyAudio Member
 
Join Date: Jan 2017
Location: Vienna
sorry to ask nooby question

in the TPA3251 dataheet /chapter 7.5 its written a gain of 20dB.

i measured with differential probe on the outputs 23 Vpp. input is 400mVrms.
psu 31V.

so 0,4vrms = > Upp= 2,828 *Urms = 2,828 *0,4 = 1,1313 Vpp

formula:
gain = 20 * log (Vou/Vin)... 20*log(23/1,1313) ......i got 26,1 dB

what did i wrong???
  Reply With Quote
Old 20th July 2018, 11:58 AM   #813
mboxler is offline mboxler  United States
diyAudio Member
 
Join Date: Nov 2011
The 20 db gain is per amplifier (each of the four). If you run speaker outs BTL you double the voltage, which equates to a 6 db increase.
  Reply With Quote
Old 20th July 2018, 01:13 PM   #814
chermann is offline chermann  Austria
diyAudio Member
 
Join Date: Jan 2017
Location: Vienna
ymmd... oohh...yes...thank you!
  Reply With Quote
Old 24th July 2018, 02:15 PM   #815
larzman is offline larzman  United States
diyAudio Member
 
Join Date: Aug 2006
Location: Chicago, IL
Quote:
Originally Posted by DPH View Post
Nope, the TI EVM's have a soldered-on tab that shorts out the output coupling capacitors (since in bridged configuration both speaker terminals are floating to the same DC value). This would be a VERY BAD THING in single ended, so you need to desolder the tabs to ensure the output is AC coupled.

I know nothing about the Nobsound parts. At $75 USD the TI EVM is very very hard to beat.
DPH, I'm curious if that statement is true for SE input & output, as TI ships the EVM in 2 channel, SE mode, with the soldered on shorting tabs present on the output caps. What is the result if used with the bridging tabs are left in place when using to drive 2 channels at 8 Ohms each? Basically, SE mode. Why would TI ship with default jumpers set to SE mode but with the bridging tabs requiring removal to use as SE? Rather odd choice by TI, but maybe I'm missing something. I want to use the EVM as SE input and SE output (driving 2, 8 Ohm speakers, one per channel).
  Reply With Quote
Old 24th July 2018, 02:57 PM   #816
catle79bay is offline catle79bay  United States
diyAudio Member
 
Join Date: Oct 2013
I sold my Tannoy LSU/Hf/12/8 last night using my tap3251 with lrs-350-36 and a raspberry pi, they really wanted the amp too, the buyers were very impressed with its clarity and dynamics. Iíve done nothing special just assembled the pieces as is.
  Reply With Quote
Old 24th July 2018, 03:23 PM   #817
DPH is online now DPH  United States
diyAudio Member
 
Join Date: Dec 2008
Location: Portland, OR
Larzman, we need to differentiate between the input and output: the board as received is configured for single ended input and bridged output. There are 4 single ended outputs on the 3255, but most people are using the amp in the stock bridged set up, where the solder tabs should remain. Single ended outputs (eg running the system in 2+1 or 4 channel mode) requires the solder tabs removed.

.
__________________
Happy DIYing, Daniel
  Reply With Quote
Old 24th July 2018, 05:06 PM   #818
DPH is online now DPH  United States
diyAudio Member
 
Join Date: Dec 2008
Location: Portland, OR
Quote:
Originally Posted by larzman View Post
Rather odd choice by TI, but maybe I'm missing something. I want to use the EVM as SE input and SE output (driving 2, 8 Ohm speakers, one per channel).
Writing more completely now that I'm not on my phone: if you're driving 2 channels in total from 1 3255 EVM board, you're running the system in bridged output. The solder tabs should remain in this configuration. If you want to drive 3 + speakers from the EVM board, then the tabs have to come off on the respective *non-bridged* outputs.

Hopefully this clears it up.
__________________
Happy DIYing, Daniel
  Reply With Quote
Old 24th July 2018, 05:27 PM   #819
larzman is offline larzman  United States
diyAudio Member
 
Join Date: Aug 2006
Location: Chicago, IL
DPH - thanks for the explanation and clarification of terms, and the very timely response as i,ve just about got everything mounted in a case and will hopefully be testing again tonight.

I got it now, so I'm leaving the tabs in for my application (bridged, SE).
  Reply With Quote
Old 24th July 2018, 05:59 PM   #820
DPH is online now DPH  United States
diyAudio Member
 
Join Date: Dec 2008
Location: Portland, OR
You're welcome; hope you enjoy it!
__________________
Happy DIYing, Daniel
  Reply With Quote

Reply


TI TPA3255EVMHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
TPA3255EVM to complete amp (advise needed) VerticalEaz Class D 69 14th August 2018 12:15 AM
tpa3255evm spacesaver mod robinlawrie Class D 84 12th December 2017 07:20 AM


New To Site? Need Help?

All times are GMT. The time now is 01:13 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki