[Juergen]

I just completed a PPA with one OPA633 per channel. On first listen it sounds harsh and lacking in bass to me (also when I switch to HA3-5002s). I realize that it needs to burn in for a while so that may be normal. I am used to my XCanV2 tube amp. I have only listened for less than an hour between the two buffer sets. I guess it's too early to judge. Does the sound change after 5 hours, ten hours .....? If it matters, I am listening with a HD600/Zu Mobius and the rest of my gear is in my profile.

 

[Megaptera]

"Harsh" and "lacking in bass" sound to me more like problems in your amp than something burn-in will take care of. (Not gonna even approach any sort of amp burn-in debate

)

I'd double-check your solder joints, make sure you've got the bass boost circuit either included or jumpered (but not open), make sure R3G isn't installed by mistake, etc. It's possible you just missed something subtle but easy to fix that's screwing with things.

 

[MisterX]

No, "burning them in" is not going to change the sound.

Edit: Remember this post to your first thread?

http://www5.head-fi.org/forums/showp...6&postcount=13

 

[Juergen]

Last night I listened for a whole half hour

Everything sounded great, go figure. I really haven't had any time lately to spend listening so every time I try it's rushed. I just need to relax.

 

[Megaptera]

Quote:

Originally Posted by Juergen Last night I listened for a whole half hour Everything sounded great, go figure. I really haven't had any time lately to spend listening so every time I try it's rushed. I just need to relax.

That'll do it too

Give yourself an evening to sit down and really listen closely to the amp. By then you'll have a good idea of how it's performing.

 

[ppl]

PPA versions prior to 1.1 are not the best for the high speed buffer possibility in the PPA these being the HA-5033 and OPA633. I mentioned changes reqired to make these parts usefull in the PPA on this page http://www5.head-fi.org/forums/showt...ghlight=HA5033

 

[tangent]

What op-amps are you using in that PPA, Juergen?

 

[Juergen]

Quote:

Originally Posted by tangent What op-amps are you using in that PPA, Juergen?

I've got OPA627s. I will be using the Intersil buffers until I get some heat sinks for the 633s, they get real hot (takes the term 'burn-in' to a new level

). As soon as Glassman's second batch of Diamond buffers are ready I will probably go that route.

 

[bpribadi]

For AD8620, the sound change significantly after 15 hours burn in (now it is even better). So Op-Amp does benefit from burn in. Previously the treble sounds harsh and sharp. Now much smoother, no more harsh and sharp treble.

I hear significant changes only on the treble, the bass and mid seems only sounds a little bit better.

You can see my short review here:
http://www.sgheadphones.net/index.ph...pic=2571&st=30

But I'm not sure about OPA627