| Originally Posted by theBigD /img/forum/go_quote.gif Maybe try AD8397 with ADA4899-1 on 'Ground' channel *shrug*. where can i get these op amps? will they plug right into the board or do they need brown dog adapters? i am really a noob especially in the amp market. any help is appreciated. |
| Originally Posted by theBigD /img/forum/go_quote.gif is there a guide to soldering on adapter? is this a pretty easy operation? i have been interested in getting into the whole diy soldering thing. very interested in trying the hotrodding the xfi card. looks pretty inexpensive as far as op amp prices. |
| Originally Posted by Filburt /img/forum/go_quote.gif Hmm, I remembered a different practical result from the 8620 when I tested that, but maybe I am thinking of a different part. I don't think the impedance comes out so low when trying to drive something like headphones (especially since the load is variable, which brings into account the overall stability of the system), but maybe I'm wrong on that. I wouldn't use the 6171/2 as the benchmark, though, as it suffers in several areas in terms of performance. I can't find anything in the SSO specs that gives sufficient data to extrapolate recovery on headphones; my experience with the chip gave the impression that it wasn't that stellar at low impedance, but it could be something else was responsible for this. Maybe I was thinking of a different part for some of the criticisms, although I didn't think so...odd. I've tried to use the 8610 several times in audio, though, and have never gotten particularly exemplary results, either in listening tests or running it on some test equipment. Subjectively, I think it sounds inferior to much of AD's suitable offerings, but I guess it isn't the worst I've ever heard, although it was one of the worst I'd tested in the PINT. In terms of measured performance, I didn't manage to get out of it what I expected by the hype of its datasheet, although I think some of the criticisms of the 627 that it points out are fair, and it did perform better than something like the 6172. After using about 50 or 60 op-amps now in various duties, I still don't think the 8610/20 is really a good choice, especially for this kind of application. I didn't get around to testing it but maybe its problem is something like TIMD or something related rather than simple HD problems...or something else that isn't occurring to me at the moment. Unfortunately, AD doesn't provide a plot from DC of the open loop response, though the very high gain at DC and relatively low slew rate suggests that it's probably not very wide. That isn't always fatal but it does seem to be detrimental to performance with some designs. The 8610 seems to perform considerably better with a buffer at its output, which is one thing that made me look to recovery amongst other things, although still not what I'd consider a high performance choice for audio. |
| Originally Posted by Moloko /img/forum/go_quote.gif To keep things down to earth, I guess it's essentially the output current of a chip that determines whether it can drive headphones of low impedance efficiently or less so. Period. That's the only reason why I'd judge the AD8610/20 "so and so" for a unbuffered headphone amp. If the output current doesn't exceed by far the actual requirements of your headphones, in my experience, the sound becomes thin, dynamically flat and emotionally boring. To exemplify... I'd certainly consider something like the AD8532 far better than something like the AD8620 for a low impedance headphone load. |
| Originally Posted by DDF /img/forum/go_quote.gif Well, in this case, the 8620 sounds anything other than thin and boring. It sounds the exact opposite, as if the contrast was almost too high. I have it running right now with some low impedance cans. |
| Like anything audio, more than 1 spec matters and o/p current is critical, bu not the only spec. If only it was so easy. Noise with source impedance, stability into capacitive loads, dc offset etc etc etc..... |
