[Porksoda]

Just curious why the PIMETA and MINT use BB buffers in stead of the more well-regarded intersil buffers used by the PPA v1 and by Headroom. A quick look at the datasheet suggests that they perform similarly at battery type voltages, but of course that doesn't tell the whole story...


Just curious what the reasoning is behind this...

 

[DaKi][er]

one big reason i can think of straight away is availability

bu634 being very easy to get from mouser digikey and tangent for the smd ones while the intersil ones only coming from newark that i know of are a bitch to deal with and completly out of the question for international buyers (like me

)

 

[Clutz]

Out of curiousity, why the interest in intersil buffers instead of the BUF634? Are they superior for audio purposes?

 

[nikongod]

Quote:

Originally Posted by Clutz Out of curiousity, why the interest in intersil buffers instead of the BUF634? Are they superior for audio purposes?

yes, the sound gooder (from what i have read) more neutral, and perhaps a bit harsher. harshness say a spicy hot roasted jalepeno may not be as bead as "buttered steak" depending on your mood/opinion.

they lack output protection, if you short them to ground, they will fry. this lack of a "feature" in one area allows them better performance elsewhere. there is probably more to their "superiority" than this allone...

 

[Jazper]

Quote:

Originally Posted by nikongod yes, the sound gooder (from what i have read) more neutral, and perhaps a bit harsher. harshness say a spicy hot roasted jalepeno may not be as bead as "buttered steak" depending on your mood/opinion. they lack output protection, if you short them to ground, they will fry. this lack of a "feature" in one area allows them better performance elsewhere. there is probably more to their "superiority" than this allone...

if you want cleaner,crisper sound... consider going to the trouble of using 2x tpa6120a2 chips on modified pcbs with appropriate pinouts for the pimeta and ppa..

THAT will sound "GOODER"

 

[skyskraper]

open up the band width, roll the op amps. no need for any modifications or whatever. you have a "crisp" sound.

the intersils have a different pin out configuration to the buf634's

 

[Jazper]

to do that it looks like you should jumper the R11 resistors on the pimeta(same R11 on the mint) - but don't quote me on that, I've never built one.

edit: after reading of datasheets and looking at layouts/schematics R11 seems to be the right one to jumper.. but that'll give you 180mhz worth of bandwidth...

 

[setmenu]

I made up some adapters and replaced the 634s in a pimeta a while back.
I very much preferred the sound.
For portable use they do consume more quiescent current than a 634 in a low
bandwidth setting but then on the other hand they sound pretty nice without
the need for stacking.



Setmenu

 

[tangent]

1. Unconditionally high quiescent current. These are both primarily portable amps, remember. You can stack BUF634s 2x and still have less than half the quiescent current drain. Even when current isn't a concern, the recommended R11 for these amps makes the BUF634 drain no more than an HA5002, so the Intersil is at best even on this score.

2. No output protection. This is critical in portable amps, where 1/8" plugs are most popular. It is far easier to short the right channel to ground through the plug with 1/8" plugs than with quarter-inchers.

3. For the MINT, the surface-mount version of the HA-5002 is too big.

4. HA-5002s can't be stacked. You have to use current-sharing resistors with them.

None of these were problems with the PPAv1. I agree, the HA-5002s sound better than BUF634s. But they're just not practical for the PIMETA or MINT.