TPA3251d2 - Page 101

Eldam · 6th July 2016, 10:46 PM

Btw, where can we find Dr M. 3521 pcb offer ? (be it populated or not)...,? I have not been following the thread lately !

doctormord · 6th July 2016, 10:51 PM

@cloud, did you got your boards up and running?

cloud1972 · 11:29 PM

yes one of them still not put it in case and using a 32v smps of poor quality and yet im still very impressed with the sound considering i have only had 5 hours of listening i have a feeling it will replace my trupath ta3020 in my system waiting for connexelectronic power supply then it's time to make it really sing
do you think a LDR pre amp stage would make a good partner for this build?

doctormord · 7th July 2016, 08:41 PM

Never used an LDR stage.

doctormord · 3rd August 2016, 12:04 AM

Finally managed to get my case done.

TPA3251 (TPA3255) aka ?Model Tiny? in Aluminiumgehäuse ? #360customs

TPA3251 "Model Tiny":

Class D Amp Photo Gallery-img_8844_1200-jpg

Class D Amp Photo Gallery-img_8838_1200-jpg

Class D Amp Photo Gallery-img_8849_1200-jpg

Hope to get the revision done on the blue board soon to order some new boards. (Finally for the DIYers)

easp · 3rd August 2016, 12:54 AM

Nice, Doctormord!

I'm curious about the thermal bridge. I've seen the photos on your site, but I'm not clear on a few things. Is there just one? Is it affixed to the case, or the board/chip? Is there just one silicone pad? You refer to the plates as "soldered" do you solder them to the top of the chip, or did you build them up be soldering together thinner sheets?

Thanks.

doctormord · 01:19 AM

Thanks for the question. The heat bridge consists of 3 copper sheets which are polished first and then soldered together by reflow and solder paste. This then gets connected to the case by the thin thermal pad as the case isn't that flat due to the manufacturing process of extruding. The thermal connection between the 3251's thermal pad and the heat bridge is just "press fit" without any grease as the thin top copper sheet is rather soft.

Doing so, the heat bridge sits straight and tight on the 3251's top pad with minimal thermal resistance, any non-flatness is carried out by the thermal pad.

The solution is able to handle 100Wrms (or 2x50Wrms) continuous output power at 30°C ambient. Thermal flow is quite good as the case is heating up quickly to about 60°C. With an efficiency of 90% there's 10W thermal loss at 100W output power, so the solution is at ~3K/W. When listening to music higher output power isn't a problem due to "burst"/crest factor.

The only limiting factor then is the inductors saturation current limit at ~8A.

easp · 3rd August 2016, 01:23 AM

Cool, thanks for the details!

Kindhornman · 3rd August 2016, 03:37 AM

doctoemord are you selling the small boards or just the larger boards to diy'ers. I would love to get a pair of boards to go with some prototype work I am doing. It will be one part of a development project using the ADAU1701 chip.

Thank you,
Steven

jencelo · 16th August 2016, 01:03 PM

@doctormord: Do you have any update on the amps/boards? Thanks.

6th July 2016, 10:51 PM	#1002
doctormord diyAudio Member Join Date: Oct 2007	@cloud, did you got your boards up and running? __________________ 360customs.de Projects: MAX9709 TPA3132D2 TPA351/TPA3255 - SigmaDSP - CSR8645 - BQ24450 LTC3784 1200W Polyphase Boost - LM5069 Hotswap Controller

6th July 2016, 11:28 PM	#1003
cloud1972 diyAudio Member Join Date: Sep 2014	yes one of them still not put it in case and using a 32v smps of poor quality and yet im still very impressed with the sound considering i have only had 5 hours of listening i have a feeling it will replace my trupath ta3020 in my system waiting for connexelectronic power supply then it's time to make it really sing do you think a LDR pre amp stage would make a good partner for this build? Last edited by cloud1972; 6th July 2016 at 11:29 PM. Reason: spell mistake

7th July 2016, 08:41 PM	#1004
doctormord diyAudio Member Join Date: Oct 2007	Never used an LDR stage. __________________ 360customs.de Projects: MAX9709 TPA3132D2 TPA351/TPA3255 - SigmaDSP - CSR8645 - BQ24450 LTC3784 1200W Polyphase Boost - LM5069 Hotswap Controller

3rd August 2016, 12:04 AM	#1005
doctormord diyAudio Member Join Date: Oct 2007	Finally managed to get my case done. TPA3251 (TPA3255) aka ?Model Tiny? in Aluminiumgehäuse ? #360customs TPA3251 "Model Tiny": Hope to get the revision done on the blue board soon to order some new boards. (Finally for the DIYers) __________________ 360customs.de Projects: MAX9709 TPA3132D2 TPA351/TPA3255 - SigmaDSP - CSR8645 - BQ24450 LTC3784 1200W Polyphase Boost - LM5069 Hotswap Controller

3rd August 2016, 01:11 AM	#1007
doctormord diyAudio Member Join Date: Oct 2007	Thanks for the question. The heat bridge consists of 3 copper sheets which are polished first and then soldered together by reflow and solder paste. This then gets connected to the case by the thin thermal pad as the case isn't that flat due to the manufacturing process of extruding. The thermal connection between the 3251's thermal pad and the heat bridge is just "press fit" without any grease as the thin top copper sheet is rather soft. Doing so, the heat bridge sits straight and tight on the 3251's top pad with minimal thermal resistance, any non-flatness is carried out by the thermal pad. The solution is able to handle 100Wrms (or 2x50Wrms) continuous output power at 30°C ambient. Thermal flow is quite good as the case is heating up quickly to about 60°C. With an efficiency of 90% there's 10W thermal loss at 100W output power, so the solution is at ~3K/W. When listening to music higher output power isn't a problem due to "burst"/crest factor. The only limiting factor then is the inductors saturation current limit at ~8A. __________________ 360customs.de Projects: MAX9709 TPA3132D2 TPA351/TPA3255 - SigmaDSP - CSR8645 - BQ24450 LTC3784 1200W Polyphase Boost - LM5069 Hotswap Controller Last edited by doctormord; 3rd August 2016 at 01:19 AM.


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6th July 2016, 10:46 PM	#1001
Eldam Banned Join Date: Sep 2012 Location: France	Btw, where can we find Dr M. 3521 pcb offer ? (be it populated or not)...,? I have not been following the thread lately !

3rd August 2016, 12:54 AM	#1006
easp diyAudio Member Join Date: May 2016	Nice, Doctormord! I'm curious about the thermal bridge. I've seen the photos on your site, but I'm not clear on a few things. Is there just one? Is it affixed to the case, or the board/chip? Is there just one silicone pad? You refer to the plates as "soldered" do you solder them to the top of the chip, or did you build them up be soldering together thinner sheets? Thanks.

3rd August 2016, 01:23 AM	#1008
easp diyAudio Member Join Date: May 2016	Cool, thanks for the details!

3rd August 2016, 03:37 AM	#1009
Kindhornman diyAudio Member Join Date: Aug 2012 Location: Los Angeles, California	doctoemord are you selling the small boards or just the larger boards to diy'ers. I would love to get a pair of boards to go with some prototype work I am doing. It will be one part of a development project using the ADAU1701 chip. Thank you, Steven

16th August 2016, 01:03 PM	#1010
jencelo diyAudio Member Join Date: May 2009	@doctormord: Do you have any update on the amps/boards? Thanks.

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