[steinchen]

tangent wrote on the PPA assembly guide: "... Then, touch the tops of the chips to see if they are getting warm. The buffers will get a bit warm to the touch, but they shouldn't be hot. The op-amps should be cool."

The buffers on my PPA get that warm (or may I say hot) that I can bare the touch only for a couple of seconds. The OpAmps stay cool, all voltages are perfect as far as I can see, the amp is working fine and sound is GREAT.

What could be the reason for the buffers are getting that warm/hot ? Voltage is fine on all buffers (24V - 0.6V that drop on the protection diode = 23.4 V). I'm using opa633kp buffers since the Intersil buffers are very difficult to get in Europe :/

 

[MisterX]

Those buffers run VERY hot and as such you might want to consider installing heatsinks on them.

 

[setmenu]

Quote:

Originally Posted by steinchen I'm using opa633kp buffers since the Intersil buffers are very difficult to get in Europe :/

http://de.farnell.com/jsp/endecaSear...=gensearch&y=9

To my ear, the HA 5002 buffer sounds way nicer than the buff 634.....

Setmenu

 

[steinchen]

I already thought about installing heat sinks but wanted to be sure that I didn't made a mistake while assembling the amp. The buffers run that hot that I definately will install heat sinks (and maybe some ventilation holes into the enclosure

)

tnx for the info

 

[steinchen]

Quote:

Originally Posted by setmenu http://de.farnell.com/jsp/endecaSear...=gensearch&y=9 To my ear, the HA 5002 buffer sounds way nicer than the buff 634..... Setmenu

I tried to order them via Newark/Farnell Germany but they changed their terms and conditions of business and only sell to business partners and students *lol* and declined my order

The only source seems to be Farnell in the U.S. with quite high shipping costs. So I decided to take the opa633 buffers ...

...but I don't mind, even with opa633 buffers the PPA sounds great and I will build a second PPA with diamond buffers or the new v2 Version anyway

 

[Juergen]

Quote:

Originally Posted by steinchen The buffers on my PPA get that warm (or may I say hot) that I can bare the touch only for a couple of seconds. /

I have the same issue on my PPA. I then tried the Intersils and they do not get hot at all

. I have some heatsinks coming because I think I like the BB buffers better.

 

[amb]

The amount of heat is directly related to the power being dissipated by the device. With the OPA533, its quiescent current is 21mA, which is about 2.5x that of the HA5002. If you are running a 24V power supply then each OPA533 will be dissipating 500mW compared to 200mW for the HA5002. And this is at idle. If you run a lo-Z load and play your music loud, then the current goes up and the temperature will rise.

 

[ramuman]

Of the buffers I've used in my PPA, the 5002s ran the coolest with the 633s the hottest by far. The 5033s and the Diamond Buffer's transistors get pretty warm - more than the 5002s ever did but not like the 633s. I think you're fine, but I do agree with suggestions to heat sink it. I never heatsinked mine, but never used them for too long before going to the 5002s and eventually the Diamonds. Congrats on the build

 

[tangent]

In addition to what amb said, the 633s have a higher bandwidth than the 5002s, so there's a greater possibility of oscillation. You really need C3 installed with 633s.

 

[steinchen]

I installed all caps before the first run, to me it's a "won't hurt may help" thing

I installed large heatsinks onto the buffers (20x20x20mm sink for graphics card BGA RAM chips) and even those are getting really hot

If I knew that before I had ordered the Intersil buffers ...

PPA with heatsinks on buffers

opa633 aren't buffers, they're little cogeneration plants :/

 

[amb]

Quote:

Originally Posted by steinchen I installed large heatsinks onto the buffers (20x20x20mm sink for graphics card BGA RAM chips) and even those are getting really hot If I knew that before I had ordered the Intersil buffers ... PPA with heatsinks on buffers opa633 aren't buffers, they're little cogeneration plants :/

Looks pretty cool (pun intended)!

 

[Juergen]

Quote:

Originally Posted by steinchen I installed large heatsinks onto the buffers....

How did you attach them?

 

[steinchen]

Quote:

Originally Posted by amb Looks pretty cool (pun intended)!

may look cool, but is/gets hot

 

[steinchen]

Quote:

Originally Posted by Juergen How did you attach them?

they had preinstalled adhesive pads, just had to pull off the protection foil and press the sink for a couple of seconds onto the chips

 

[tangent]

Would you happen to know that amp's quiescent current?