0 Members and 1 Guest are viewing this topic. Read 14934 times.
I prefer to think of it as the Great Dean Divide, Hugh vs. James. Not that Hugh doesn't gadabout on his tricked out motorcycle, pushing limits, both legal and his own.....
I have experimented building solid state amplifiers capable of up to 3MGz frequency bandwidth. The very best results sonically and measurement wise are achieved by using jfets in the input stage. More importantly millitary metal can style dual jfets. They have a very high input impedence which is desirable and can lead to very high slew rate circuits. The following stages would comprise of high frequency bipolar video transistors.The higher the slew rate, the wider the frequancy band of the amplifier. The wider the frequancy band, the lower will be phase and time errors.
What differentiates live music from recorded is the transient response, the closer phase error and time error is to zero, the closer the sound will be to a live performance.
Well, after Legarem posted on the Paradisea thread about the LM4562 (thanks Lagarem!) -http://www.audiocircle.com/index.php?topic=33534.msg299780#msg299780and finished my power amp rebuild, I actually decided to try these National duals.So I replaced the OPA2111 dual opamp that was in the center, output position for a LM4562NA (8 pin dip) in my Zhaolu 2.0 dac. Shazzam! Not as warm sounding as the OPA2107, but very resolving and excellent extention in the bass as treble. Its working marvelously with the remaining 2 OPA2107s feeding it from the dac. What I really like about this chip (like the OPA2107) is its sensible bandwidth and slew rate, 55mHz and 20v/uS, which means its unlikely to misbehave when swapped for another dual opamp. (not that most circuits don't benefit from improved ps decoupling, but its nice when you can just swap without jumping through hoops)So now I've got 2 'standardized' dual general purpose opamps in my arsenal. For a slightly warm (tubey) sound I've the BB OPA2107 and for absolute neutrality (whatever that means) with resolution and extension (the 2107 isn't far behind) I've the National LM4562. This isn't to say that they're aren't other chips better for specific applications, but I will say that I can't see a reason for using/leaving any OPA2604/2132/2134, other than a small cost saving.
Well iff'n you want soic you need the MA suffix chip rather than the dip versions which have the NA suffix.Now this comment is purely second hand.... if you're using the CRD (current regulating diode to bias the opamp into class A) on the Hypex board, you want to tie it to the + rail, as opposed the the way it comes configured, tied to the - rail.