[slayer6288]

What are the best op amps for this combination and what setting do u reccomend the high gain which is to 250 ohm max or the 250 ohm plus one?

 

[PurpleAngel]

Quote:

What are the best op amps for this combination and what setting do u recomend the high gain which is to 250 ohm max or the 250 ohm plus one?

I'm enjoying the AD797BR's op-amps.

 

[slayer6288]

anyone else? and also what setting should I have the amp set to for hd650s

 

[stv014]

The gain setting is basically just a volume control, use whatever is loud enough at a "normal" (not very low or high) volume setting.
 
Regarding op-amps, I do not really believe they make much, if any useful difference, but care is needed with the AD797 in particular, since it is a very "fast" IC (110 MHz bandwidth compared to only 13 MHz with the stock NJM2114's), and is known to be difficult to implement properly and prone to oscillation (some examples of that can be found in the Essence One thread). I do not know if anyone with a sufficiently high speed oscilloscope tested the STX/AD797 combination for stability.

 

[slayer6288]

any other imput on ohm setting for the stx and the op amps?

 

[Funky-kun]

Ohm setting only affects gain, so use whichever gives you comfortable range on the volume control. I believe I used the middle one.
 
 
Quote:

Originally Posted by Funky-kun /img/forum/go_quote.gif Talking about opamps, I think I've ended my quest for the perfect ones. Here are my impressions. All testing done through HP out with HD650s. JRC2114 (default) : I actually think the default opamp for the card is a really good choice. Had it not been for the bassy and dark signature of my cans, I would have kept these. They actually sound the best with my HD595s. Bass is very deep, with perfect extension, just a bit too much in quality for the HD650s. The highs tend to be a bit rolled off, and the soundstage is pretty wide, but not deep and high. I imagine these would sound fantastic with headphones like K701/2 or DT880, but is too heavy for my current cans. LT1364 : I didn't like these very much. Bass seems neutral, but lacks punch. Mid and highs are well balanced, but soundstage isn't that much better than 2114. Detail is improved. Sounds too weightless. OPA2134 : Disappointment. As Alienns stated, the default opamps are just better. These have more bass, but the quality is degraded in comparison. With these opamps the bass on 650s sounded like the one on my HD212. (read: boomy) Highs are also rolled off. The soundstage isn't impressive, but opens a bit after burn-in. Sounded "dense", in the sense that all the sounds are too close to you and without good positioning. LME49720 : All I can say is these babies ROCK. Bass lacks just a little bit of extension, but is very natural sounding and punchy. Highs are brighter than average, but that cancels out with the dark signature of my headphones well, resulting in an overall neutral tonality. Soundstage is absolutely awesome. You can easily position instruments in direction and distance. Has the depth other opamps are missing. All details are clearly present, but the sound is a bit distant due to the soundstaging. My current and final choice. LM6172 : These are very close in sound to the LME49720. Biggest difference is that they aren't so distant sounding. That means less soundstage and a bit better bass. I didn't find the trade off worthwhile. Still a very valid choice. I hope all of you find the perfect opamp match for your headphones. I have done it.

 
While the above descriptions exaggerate the differences between opamps for the sake of comparison, each one does produce a characteristic sound which is easily discernible from the others if you pay attention (no golden ears needed).

 

[PurpleAngel]

LME49860NA, same op-amp as the LME49720NA, but the LME49860NA has a better voltage range.