DSP - how, why, tro...
 
Notifications
Clear all

DSP - how, why, troubleshooting, different hardware, etc.

Page 2 / 2

ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

@elliottdesigns - so this morning, while still waking up, I flipped an input GPIO debounce to a data line and blew up one of the amp chips in my JAB5. Turns out they use the TDA7498E chips. I have a few other SMB components right by it to check and ask the values from Sure Electronics to verify if those need replaced along with the TDA7498E, but it looks primarily like the chip being replaced may fix the issue.

20210915 101029

 At least on this board, I do not see a mirror on size of the SMB resistors that come after the amp chips.

But, looks like I will get to practice my soldering. LOL.


ReplyQuote
123Toid
(@123toid)
Illustrious Member Admin
Joined: 4 years ago
Posts: 1669
 

I really just want to say I'm enjoying following this thread. I really wish there was more that I could personally input, but this has been really awesome. I thought I would share this with you guys as well. My Patreon Philip found this and shared it with me. I hope this was a pretty amazing thing to do with sigma studios.

https://www.youtube.com/123toid


ajc9988 liked
ReplyQuote

123Toid
(@123toid)
Illustrious Member Admin
Joined: 4 years ago
Posts: 1669
 

@ajc9988 dang that's rough. I hate soldering small little components like that. 

https://www.youtube.com/123toid


ReplyQuote
TVOR-Ceasar
(@tvor-ceasar)
Honorable Member Moderator
Joined: 2 years ago
Posts: 716
 

@ajc9988 ooooh, that's not pretty. As you said, it looks like only the 7498 let out the magic smoke. The other passives look like they only have some soot on them. A little 99% isopropyl alcohol will clean that right up.

A nice micro tip on your pencil will do a good job on those legs. Just hope the pads are okay. Good luck on the repair.

-Charlie
https://www.youtube.com/user/TheTrueVoiceOfReason


ajc9988 liked
ReplyQuote

ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

@123toid - It happens. At least with shipping it is only around $6 or $7 to replace the amp chip. Also, it did give me a reason to take the heatsink and fan off to take a look at other chips used. So, now we know that the JAB5 uses 2 x TDA7498E chips.

image

Now, they rated it for 100W@6Ohm, but looking at that data sheet ( https://www.st.com/content/ccc/resource/technical/document/datasheet/ad/92/18/e8/c0/bf/42/b6/DM00044235.pdf/files/DM00044235.pdf/jcr:content/translations/en.DM00044235.pdf ) it seems that is pushing right up to the edge of the chip's performance.

160-W + 160-W output power at THD = 10% with RL = 4 Ω and VCC = 36 V
1 x 220 W output power mono parallel BTL at THD = 10% with RL = 3 Ω and
VCC = 36 V

So, even in bridged, keeping it under 150W likely is a smart play at 4Ohm, if for no other reason than trying to keep THD under 1% potentially.


ReplyQuote
ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

@tvor-ceasar That was my thought also. And initial checks with a multi-meter suggest the SMBs there are in the right range. So it should just be the chip and praying the pads are intact.


ReplyQuote

ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

@123toid - btw, found this as an example of how a person could build their own DSP from the 21489 SHARC board I showed before:

image

https://www.aliexpress.com/item/1005001659282393.html?pdp_ext_f=%7B%22ship_from%22%2212000017019877428%22%7D&scm=1007.26694.140541.0&scm_id=1007.26694.140541.0&scm-url=1007.26694.140541.0&pvid=d610eda2-8faa-4151-86ab-c11f0bd2cf30&fromRankId=11708252&_t=fromRankId:11708252

Type 8 comes with the usbi programmer and the power supply for $157.26. This listing on AliExpress has the 4 in 8 out without the programmer or the power supply unit for $125.06.

Just wanted to give an example of doing a very nice DSP for a home theater fairly easily here. Or just having a per driver out on some tower speakers or bookshelves and having the signal go from here to an amp to the drivers. Either way, just thought I'd share this because it looks good.


ReplyQuote
ElliottDesigns
(@elliottdesigns)
Estimable Member Moderator
Joined: 2 years ago
Posts: 210
 

@ajc9988 yeah, sm soldering is a real pain so good luck with that 👍. Might be worth putting a tiny dab of thermal paste on the chip before putting the heatsink back on, when driven hard those chips can get pretty hot, so the thermal paste should help reduce distortion.

Elliott Dyson - Mechanical Engineering Student and 3D printing & Design Freelancer


ajc9988 liked
ReplyQuote

ElliottDesigns
(@elliottdesigns)
Estimable Member Moderator
Joined: 2 years ago
Posts: 210
 

@ajc9988 Also you'll probably find that because it's rated for a 6ohm load you'll have sm-inductors that are rated for said 6ohm load. If you were to then use a 4ohm load you would get some high frequency attenuation, which I know is the case when seeing measurements of tpa3116 boards that have the inductance for an 8ohm load even though the suggested load on the listing is 4ohm, it's just bad design in that case, but it counts to what I'm saying anyways.

Elliott Dyson - Mechanical Engineering Student and 3D printing & Design Freelancer


ajc9988 liked
ReplyQuote
ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

@elliottdesigns - I did forget to mention that the chips did have a white thermal paste that was used which seemed to be of a decent quality. I was going to use the Kingpin KPX thermal paste I have (which I have a 50g tube of, as I mentioned, I overclock PCs as my other hobby). So definitely going to put thermal paste on before closing it back up. And KPX is a pretty good paste. Lord knows I've used Coollabs Liquid Ultra, Arctic silvers (this hobby goes back to the early 90s when I built my first computer with my dad), arctic MX4, gelid extreme, IC Diamond, Kryonaut, Prolimetech (sic?), etc.

In fact, I am using a copper shim with the RPi along with the KPx and swapped the thermal pads with the heatsink I bought for it for Thermal Grizzly pads I had left over from fitting a GPU water block awhile back.

https://www.igorslab.de/en/waermeleitpasten-chart-2/2/ (Igor used to do the thermal paste testing for Tom's Hardware before he broke off for his current YouTube and website testing).


ReplyQuote

ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

@elliottdesigns That is why with the JAB5, they do in their material say use only 6 or 8 Ohm loads, or you can bridge it to output 3 and 4 Ohm loads. In other words, if you are only pushing 4 Ohm loads, you can only use two channels with the JAB5. If you are only pushing 6 and 8 ohm loads, then you can have 3-4 channels.

I have a tweeter that is run at 6 Ohm loads, a woofer running 8 Ohms, and a subwoofer running 4 Ohm loads. So, 2.1. I blew the chip on that board for the one driving the subwoofer channel. I have an old 8 inch 3 Ohm samsung "sub" that I had plugged in at the time I toasted that chip. But, that was toasted more due to inverting a signal on a GPIO feeding the amp chip rather than pulling too much on the chip. So a different type of stupid move. LOL.

I still wish they would do more like ICE in reporting the 1% THD+Noise rather than the watts for 10%.

Either way, in future builds, I will buy the amps and DSP separate to have more control on that aspect. It isn't even saying the quality is bad on the device. Just that I now know better how to read the specs and would buy a different product better fitting my need.


ReplyQuote
ElliottDesigns
(@elliottdesigns)
Estimable Member Moderator
Joined: 2 years ago
Posts: 210
 

@ajc9988 yeah, that's why I'll probably be getting 2x100w per channel amplification and then only using 2x50 of those watts. That way I know I'll be below distortion 👍

Elliott Dyson - Mechanical Engineering Student and 3D printing & Design Freelancer


ajc9988 liked
ReplyQuote

ajc9988
(@ajc9988)
Estimable Member Registered
Joined: 6 months ago
Posts: 126
Topic starter  

Oh, found another interesting DSP board. An ADAU1452 with an AD1938 codec chip (read 4xADC, 8xDAC; 192kHz, 24-bit; -94dB THD+N) for $59.42 plus shipping.

https://www.aliexpress.com/item/1005002028126635.html?algo_pvid=09780f38-fc06-43d9-ad75-70906f657279&algo_exp_id=09780f38-fc06-43d9-ad75-70906f657279-1&pdp_ext_f=%7B%22sku_id%22%3A%2212000018461251555%22%7D

What is cool with this is that this could do about what the Teensy 4.0 does, give or take. It's a little weaker than the ADAU1466/67 chips, but not by a lot. If you add the Teensy+ADC/DAC costs, this becomes a viable alternative. And with 8 outputs, you could throw this inside a speaker without an issue and route it per driver. The two boards stack (like how the Dayton rebrand of Sure electronics adau1701 and ADC/DAC board stack), which can help for space constraints when used with a plate amp. Still have to buy the amplifier boards, but wanted to show an embedded solution I found. This price also assumes you have an USBi programmer from somewhere to interface for use with sigmastudio. Otherwise, I would buy the programmer other than from this listing.

@ElliottDesigns - since we previously compared the Teensy and the ADAU1452/66/67, I figured this might interest you.


ReplyQuote
Page 2 / 2

Newegg

Share:
%d bloggers like this: