Sure Electronics Tripath boards?

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#522
Sorry to interject but I have a situation that puzzles me.
I have two of these amps driving identical speakers.
Both work great.
One has a 16V laptop supply and the chip is cool to the touch.The other has a Canon printer 13.5V supply and after about 5 seconds I have to take my finger off the chip.I would have thought the lower voltage amp would be the coolest.
Just wondering.
Paul
 
#523
Hot headed IC's

Hi there,

I am not to sure what could be the cause of a big difference in heat dissipation, i think to check the PCB for errors would be a good idea, and check the idle current. using the IC at 16 volts how ever is not reccomended.

One possible cause is perhaps a voltage difference at the input, when using a switching power supply it should be properly grounded.

Other than that, if there is any issue at the output of the IC, perhaps somthing is shorted . also try the IC at a lower voltage and see what hapens.

BTW, is this one of my boards?


Greetings,

Arjen
 
#525
Re: Hot headed IC's

ArjenShenzhen said:
Hi there,

I am not to sure what could be the cause of a big difference in heat dissipation, i think to check the PCB for errors would be a good idea, and check the idle current. using the IC at 16 volts how ever is not reccomended.

One possible cause is perhaps a voltage difference at the input, when using a switching power supply it should be properly grounded.

Other than that, if there is any issue at the output of the IC, perhaps somthing is shorted . also try the IC at a lower voltage and see what hapens.

BTW, is this one of my boards?
I'm sorry,I should have made it clear that they are the Sure Electronics boards.
Paul

Greetings,

Arjen
Click to expand...
 
#526
hijacking

Hi there paul,

Understand, no worries im kinda hijacking this thread with my pcb's, sorry about that!

but i suggest you try to debug it, somthing must be wrong. ususally the IC either functions, or it doesnt, there is not much in between, it might very well be dead....

if you want to solder this IC you will need a hot air solder iron so thats a bit of a pain.

The IC's here are about 2/3 euro's per one... almost the same like my board.

Greetings.

Arjen
 
#527
I have connected both amps to the 16V supply and one still runs hot.
Both work perfectly.They are in use for a party tonight(bi-amp each channel),so I will check voltage offsets tomorrow.
I am using a brass bolt as a temporary heatsink and both are open mounted on top of the speaker boxes.
These are great amps and I'm getting more.
Paul
I think these little amps sound best at 16V supply,clearer and more precise.My daughters think so too.I've been using them for ages at this voltage(regulated of course)and have had no problems.
Touch wood.
 
#530
Thanks Franz, one thing is still not clear to me: in order to reach unity gain or something very close to it should I change some of the board resistors or just short a couple of the opamp's pins?

Unfortunately I still don't have the board in my hands...
Click to expand...

Pincellone

Did you receive the board? Do you know, what to modify? I have one of them and could give you the needed hints, if desired.

My desktop T-amp project is moving slowly, as I had to repair my burned out Gainclone first (see http://www.diyaudio.com/forums/showthread.php?s=&threadid=125797 and use adequate fuses and switch of your equipment, when not in use!!!).

Here the layout of my desktop amp:

An externally hosted image should be here but it was not working when we last tested it.


Because the t-amp does not produce noticeable heat, its place is now under the buffer board.

The buffer is a J-Fet buffer with its own regulated psu (both from the seller tubeshunter / eBay). I will add a small print tranny in top of the torroid. I think a small tranny is sufficient as the buffer is running in Class-A and therefore comsuming nearby constant current.

Franz
 
#534
Franz Gysi said:


Pincellone

Did you receive the board? Do you know, what to modify? I have one of them and could give you the needed hints, if desired.

My desktop T-amp project is moving slowly, as I had to repair my burned out Gainclone first (see http://www.diyaudio.com/forums/showthread.php?s=&threadid=125797 and use adequate fuses and switch of your equipment, when not in use!!!).

Here the layout of my desktop amp:

An externally hosted image should be here but it was not working when we last tested it.


Because the t-amp does not produce noticeable heat, its place is now under the buffer board.

The buffer is a J-Fet buffer with its own regulated psu (both from the seller tubeshunter / eBay). I will add a small print tranny in top of the torroid. I think a small tranny is sufficient as the buffer is running in Class-A and therefore comsuming nearby constant current.

Franz
Click to expand...


Hi Franz, thank you for your help, I actually ordered a different item from Tubeshunter, but I'm still waiting for it. It has a gain of 20db, so I guess I need to find a way to make it reach unity gain instead. If you know how to do it, please let me know.

http://cgi.ebay.it/NE5532-HI-FI-STE...12050QQcmdZViewItemQQ_trksidZp1713.m153.l1262

How is your new buffer performing? Is the difference noticeable?

Thanks!

Pincellone
 
#535
Hi Pincellone

Actually, I use the amp without buffer and it seems to work well.

I will try the buffer asap.

I have one of the same boards like you have, the opamp +20dB module.

So, should you have some questions modifying this board, dont hesitate to ask (me). 😀

I just remarked: the bypass caps are to far away from the pins of the chips.

It would be worth to add some good bypass caps directly at the pins to ground.

And to replace the ceramic caps by styroflex or mica types, should this caps really be needed.

Franz
 
#536
Thanks Franz. It is still not clear to me if you actually tried the buffer I can see in the picture with the Sure board and whether or not you found an improvement by using it compared to a volume pot directly connected to the Sure (I'm using an Alps Blu RK27 25K as I was not satisfied with the performances of the 50k and 100k).

I hope to receive the preamp board soon, the only mod would be bringing it to unity gain and use it as a preamp for the sure board (if this is really worth it...) In that case it would be interesting to know what to modify to get lower the gain as much as possible.

Pincellone
 
#537
pincellone,

to convert to unity gain buffer, find Rf from output to invert input and Rg from invert input to ground, remove both and connect with wire invert input to output.
See attach.

Zigis.
 

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#538
Zigis, thanks for the info.

I don't have the schematics of the preamp, but it seems to me that I should connect some pins of the dual opamp and remove a couple of resistors. Is that correct?

If so, could you please let me know which ones are they?

Here is the pinout of a dual opamp and the picture of the preamplifier. Thanks!

la1.jpg


An externally hosted image should be here but it was not working when we last tested it.
 
#539
Yes, you need to remove 4 resistors for stereo, hard to say by photo which one, PCB is 2 sides.

Wen you get amp, find 2 resistors who go from pin 1 to pin 2 and from pin 7 to pin 6 and remove.
Than find 2 resistors from pin 2 to ground and from pin 6 to ground and remove both.
Then connect pin 1 to 2 and 6 to 7.
Zigis.
 
#540
Wen you made unity gain buffer working, next step to improve sound quality may be add 2 el caps 50-100 mf from power pins 4 and 8 to ground, close to chip's pin.
Shunt thees el caps with small 0.1mf film cap.
On board caps is too far from chip.
 
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