Heat Dissapation Problem LME49720/OPA1632 Preamp

[alexw88]

Originally posted by artquake

Well if alexw88 would join and make an offer for the gerber files that would be great !

As you wish! It is attached.

[alexw88]

Originally posted by artquake
And then sticking wires thru the frilled holes and attaching them to a peace of copperfoil. Right ?
How can achieve good contact pressure with the wire from the bottom side to the PowerPad plane ?

I think you can try applying solder to the wire, and the solder will flow down the wire to the PowerPad and the wire will be soldered to the chip.

[artquake]

Originally posted by alexw88


As you wish! It is attached.

Originally posted by alexw88


I think you can try applying solder to the wire, and the solder will flow down the wire to the PowerPad and the wire will be soldered to the chip.

Thank you very much, i'll give those pcb's a try ! Compare (p2p/pcb) how sonic quality increases ... superbe !



Best regards
artQuake

[DigitalJunkie]

Originally posted by theAnonymous1
I know I plug this stuff way too much, but J-B KWIK WELD epoxy works wonders for holding heatsinks on. It's a whole lot cheaper than "real" thermal epoxy too.

http://jbweld.net/products/jbkwik.php

And yes, those little OPA1632 get blazing hot . I cut a fin off of an old CPU heatsink and used some KWIK WELD to hold it on.

In a pinch,I've used J-B Weld,and a few coins (pennies) glued to various chips and stuff (small bridge rects.)
You can even stack a couple pennies,or 'stagger' them (half overlapping),to make a sorta finned stack.

It works well.

[artquake]

@alexw88

Have you detected that your circuit in the schematic gives out inverted output of a signal ? I mean if signal is positive on input the output will be negative. I found this by chance while making measurements with RMAA. The Message from "Polarity" was allways detected as "inverted". When i changed the polarity it reported "correct"

I wondered that time, why the left channel report had only Stereo crosstalk between 20Hz-20kHz of approximately linear -78dB and the right channel was meanwhile @ -90dB.

After i changed the polarity the crosstalk lowered down, while noise level result was nearly constant as before changing polarity.



(remark that my first crosstalk diagramm i have posted here was allready the corrected one.)

So i think it could be useful for you and all @ here.

So these are just my 2 cents ...

Best regards
artQuake

[artquake]

Originally posted by artquake
@alexw88

Have you detected that your circuit in the schematic gives out inverted output of a signal ?

Sorry that was my fault, refering back to your schematic i missed up +&- @OPA1632 Output so no offense.

BTW: I'm getting the boards done (Get them in about 1 or 2 weeks)

regards
artQuake

[artquake]

Finally got the boards.



Thank u once more alexw88 for support.

Will assemble them soon ... i wonder if this boards will give better results ...

Best regards
artQuake

[alexw88]

Blue PCB looks nice! To solder the 1632 thermal pad is not easy, good luck!

[juma]

Originally posted by jackinnj


quote:
Originally posted by artquake

Do i have also have some human feelings of heat ?


this will be the case until you get married.

Sorry for OT, but those simple human feelings are irresistible. I nominate artquake for "Most Sincere Question" award and jackinnj for "Lakonian Answer of the Year".
Thanks guys, you made my day!

[artquake]

Alex, the thermal pad is really easy to solder, capillary forces helping the solder to flow under the chip, while heating from the bottom side of the pcb. Only the heat during soldering made me thinking.

But soldering the legs of the OPA is pure surgery .

Here some results with RMAA from p2p soldering board (before) and the new pcb board.

Noise with p2p soldered


Noise with new pcb


Crosstalk with p2p soldered


Crosstalk with new pcb


Summary p2p soldered
Frequency response (from 40 Hz to 15 kHz), dB +0.05, -0.01 Excellent
Noise level, dB (A) -98.3 Excellent
Dynamic range, dB (A) 92.5 Very good
THD, % 0.012 Good
THD + Noise, dB (A) -75.4 Average
IMD + Noise, % 0.015 Very good
Stereo crosstalk, dB -95.4 Excellent
IMD at 10 kHz, % 0.015 Very good
General performance Very good

Summary new pcb
Frequency response (from 40 Hz to 15 kHz), dB +0.07, -0.15 Very good
Noise level, dB (A) -97.3 Excellent
Dynamic range, dB (A) 92.1 Very good
THD, % 0.019 Good
THD + Noise, dB (A) -71.7 Average
IMD + Noise, % 0.023 Good
Stereo crosstalk, dB -96.2 Excellent
IMD at 10 kHz, % 0.022 Good
General performance Very good

Interesting that the general performance of the p2p soldered got tiny better results ...

I'll test it once more when i get the better remote controlled stepped attenuator inside the circuit ... @ the moment i'm using two 1 $ stereo 10 k Pots ... but result is good.

Have you / or maybee others got about same results ? Or is there something questionable in the data ?
Specially for THD + Noise.

artQuake