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Oh no, not again! What Opamps for a PPA?

post #1 of 31
Thread Starter 
I understand that some folks might find it annoying that I'm asking this question AGAIN, but hey! I've included a funny poll this time.

I just can't decide what opamps I should use in my PPAv2. (I'll probably try all three alternatives eventually, but I can't decide what to try first.)

The PPAv2 will have a STEPS psu and a modified Linkwitz crossfeed filter, and will drive Sennheiser HD650 headphones.

Here are my thoughts:


AD8610:

Browndog adapters make the signal path longer, which might hurt the sound quality, but then again: That might be stupid nitpicking, and something that I'll NEVER be able to hear in real life.

The AD8610s are supposed to be the brightest and most detailed of my three alternatives, right? I was thinking that this might make good synergy with my dark sounding HD650s? Also, this seems to be the preferred opamp of "Team PPA" for this amp.



OPA627:

Good, but warm/dark/laidback sounding. Might be a bit much when paired with the already warm/dark HD650s. Easier to work with due to not needing Browndog adapters.



OPA637 on L+R channels and OPA627 on ground channel:

Sort of a compromise between the two above. A bit less dark/warm sounding than three 727s, but still "burr browny". More lively sound due to higher bandwidth in the 637s (Or will this advantage be lost anyway, due to the 627 in the ground channel?)



Please vote if you have experience or knowledge regarding these setups. I know I could just roll opamps and try them all, but I'd really prefer to keep it as simple as possible from the start, and just order the most promising alternative.

Your vote will be worth a whole lot more to me if you reply with a comment expplaining your vote, of course.

Thanks in advance!
post #2 of 31
Just quickly - the browndogs will not effect sound quality at all. No need to take that into consideration.

Rob.
post #3 of 31
you forgot to list AD843 :X
and AD8065 ... and ...

there are many opamps that work fine in a PPA, many people sonically prefer the OPA637, I personally don't like them and prefer AD843, in the end it's a question of personal preference
post #4 of 31
Thread Starter 
Quote:
Originally Posted by steinchen
you forgot to list AD843 :X
and AD8065 ... and ...
Thanks, but no, I didn't. I'm just trying to choose from these three alternatives now. Do these opamps have the same pin configurations as the ones I mentioned, so that they are drop-in replacements for them? Are there other "adjustments" that have do be made in the amp to make them work?

Quote:
Originally Posted by steinchen
there are many opamps that work fine in a PPA, many people sonically prefer the OPA637, I personally don't like them and prefer AD843, in the end it's a question of personal preference
Feel free to elaborate. Why do you like the AD843?
post #5 of 31
post #6 of 31
Quote:
Originally Posted by steinba
Do these opamps have the same pin configurations as the ones I mentioned, so that they are drop-in replacements for them?
yes
http://alldatasheet.com/view.jsp?Searchword=AD8065

Quote:
Originally Posted by steinba
Are there other "adjustments" that have do be made in the amp to make them work?
no

Quote:
Originally Posted by steinba
Feel free to elaborate. Why do you like the AD843?
because it is warm and silky sounding, has a decent bass punch, still enough detail (for me) and that's what I like and prefer

btw, if you are interested in the sonic signatures of opamps I recommend tangent's note on audio opamps. Additionally head-fi's search function will find zillions of threads related to this topic.
post #7 of 31
I'm using the AD8620 + TPA6120 for driving an HD650 and I must say that it sounds wonderfully!

The AD8620 (double version of the AD8610) gives really a brilliant sound compared to some OPAxx that I tested. Probably the HD650, that has some slight "fog" on the high frequencies (personal opinion obviously), has great benefits from a bright sounding chip like the AD8620 or AD8610.

This is my project with these chips.
post #8 of 31
The AD8065 should be a lot better choice than the AD8610, I have right now in mine the THS4631 a lot cheaper and IMO better performer all around, better details and extension, and a super-fast chip...
post #9 of 31
Thread Starter 
The way I understand it, the only difference between an OPA627 ans an OPA637 is that the 637 has a higher bandwidth than the 627, and that makes the sound "more lively". BUT: Will I actually be able to benefit from this as long as I have to use a (bandwidth-limiting?) OPA627 in the ground channel?
post #10 of 31
Personally, I wouldn't go with anything brighter than the 637/627... I love my PPA w/ that combo. I plan on doing some back to back of 637/627 vs. 627 at some point and I'll post if there's a noticable difference.
post #11 of 31
Thread Starter 
Quote:
Originally Posted by steinba
The way I understand it, the only difference between an OPA627 ans an OPA637 is that the 637 has a higher bandwidth than the 627, and that makes the sound "more lively". BUT: Will I actually be able to benefit from this as long as I have to use a (bandwidth-limiting?) OPA627 in the ground channel?
No suggestions?
post #12 of 31
Quote:
Originally Posted by en480c4
Personally, I wouldn't go with anything brighter than the 637/627... I love my PPA w/ that combo. I plan on doing some back to back of 637/627 vs. 627 at some point and I'll post if there's a noticable difference.
You can get the same sound with more sparkle, and details with other OPamps, and noit necesarily should be brighter, any way one of the good things of the PPA is that you can OProlling it with no problems, but one thing I know for sure, and is that I will never say I will not like this unless I've tried it, that dog bite me in the past. I tried the AD8610 and never liked it, while ppl told me to try the AD8065, I said what the heck another bright OPamp? Tried it and I absolutelly love them...later on the "Speed King" came and they are there till now, and I do not like bright presentations, well I can't have them actually.....and I have here OPA637's and 627's BP and AP from the same batch and matched, along with another OPAmps, so it is not for the lack of them....
post #13 of 31
Quote:
Originally Posted by steinba
The way I understand it, the only difference between an OPA627 ans an OPA637 is that the 637 has a higher bandwidth than the 627, and that makes the sound "more lively". BUT: Will I actually be able to benefit from this as long as I have to use a (bandwidth-limiting?) OPA627 in the ground channel?
you will benefit, the ground channel opamp won't (audibly) change the sonic signature, the left and right channel opamps do that
post #14 of 31
I am using the 627/637 combo in mine. I built the bass boost into it, and the LM crossfeed. While I have not tried any other chips in mine, I think my PPA sounds awesome.
post #15 of 31
Thread Starter 
Quote:
Originally Posted by steinchen
you will benefit, the ground channel opamp won't (audibly) change the sonic signature, the left and right channel opamps do that
Yeah, but the signal from the left and right channels has to go trough the ground channel as well, so if that channel has less bandwidth, won't the difference in bandwidth be filtered away trough the ground channel. (Hmmm. Badly put, but hopefully you get my meaning.)
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