AD8620 vs. AD843 Bass?

[Stew]

I have been rolling opamps in a Yamaha CD player and have tried OPA2134, AD823, AD826, and AD8620 so far. AD826 wins hands down for I/V. I'm currently using AD8620 for output buffers and they have the best imaging, soundstage, air, detail, smoothness, etc. so far but don't quite have the bass slam of AD826.

From searching, AD843 should sound similar to AD8610/8620 but with more bass. I'm wondering if AD843 sounds like AD8620 with the bass control turned up a couple of db or if it has more slam like AD826. The AD8620's sound great with 2 db bass boost but it might be worth the trouble to try AD843's if the bass is more dynamic. Also, which of these two is considered more detailed? All comments appreciated!

Stew

[dsavitsk]

You should start by reading this: http://www.tangentsoft.net/audio/opamps.html

Sometimes with opamps, you can influence the bass through the capacitors. Increasing either the amount or the speed of the caps can do wonders for bringing out bass, and soft bass is often a symptom of too small caps. If you like the 8620, I'd sick with it, find some nearby rail caps, and replace them with twice the capacitance usinga decent quality cap like a Panasonic FM. You might also try bypassing them with film and foil or at least MKP caps.

[Extreme_Boky]

Try AD8066 as I/V and OP275 (“more bass”) as buffer / analog filter.
AD826 sounds very good - one of my favourites.

I played recently with transistor I/V circuits (available here on forums!) and in my opinion they are a league above any IC. But if you want and have to stay with OP’s - try AD8066. It’s a winner when it comes to I/V and sounds very good compared with transistor I/V stages. The best sound (most natural) I obtained was with a resistor as an I/V, but this approach puts some special requirements on interconnects and amplification.

Extreme_Boky

[Stew]

Thanks for the replies.

dsavitsk - I'll take a look at the caps. The article you referenced is a good read!

Extreme_Boky - Did you try AD8066 for buffers? I was thinking about leaving AD826 for I/V and trying AD8066 for buffers. Maybe I should try the reverse as well. How did AD8066 compare to AD826 for I/V?

I really liked AD826 for buffers too except the upper mids/highs could be a little harsh at times. Great rhythm, bass, natural vocals, etc. Perfection to me would be AD826 low and mid bass with a little more smoothness and detail for the upper mids and highs. I seem to be acquiring a sack full of opamps in pursuit of that goal!

[Extreme_Boky]

Extreme_Boky - Did you try AD8066 for buffers? I was thinking about leaving AD826 for I/V and trying AD8066 for buffers. Maybe I should try the reverse as well. How did AD8066 compare to AD826 for I/V?

I don't think AD8066 is suitable for buffering at all. However, I did try this IC (just for the sake of it...) as a buffer IC and I didn't like it at all. AD826 and OP275 are much better suited for this application, and they sound better as well.

It's different story when it comes to I/V conversion - AD8066's fast settling time and very low input bias current are perfect for detail retrieval. This proved to be the case when I did the listening tests. Detail retrieval, space around instruments, frequency extremes - all excellent. This IC is very revealing and requires attention around all other sections of the CD player / DAC. Otherwise the sound becomes too harsh and unlistenable.

There is a possibility to parallel two halfs of the buffer IC - if only one half is in use by design. This gives much better control and drive capabilities. I tried this with OP275's and AD826 it worked and sounded great.

Extreme_Boky