Input buffer for UcD: LM4562 better than AD8620?

[Alfetta87]

After our tests with some bulky and expensive amps on top equipment (UcD400 listening vs. Halcro & Gamut), I decided to change the input buffer on my UcD's 400.

I ordered 2 LM4562, and replaced the AD8620 on the UcD boards.

After a few hours of playing, the surprise was big: the amp played better than before!
On the "negative" side, I have to say that the tonal balance changed: less weighty in the LF region, and more brilliant on the upper limit.
Some measurements on and Audio Precision didn't confirm this tendency, so I had to play with different power cords and interconnects, to get the balance right.
On the positive side, there is everything: extreme transparency, warmth and presence in the lower midrange, open but not foreward midrange, extension on both ends. Image remained same as before: stable and detailed. The UcD came damn close(r) the the Halcro DM88, which had a different balance.

I ordered another 2 OpAmps in DIL8, and replaced the ouput amps of my CD player (also AD8620) with the LM's, here the balance was similar but not so pronounced. Together I was afraid that the tonal balance would be pronounced like described before, but it seems after a few days of burning in, it is quite OK. Not suitable for small speakers with a tiny 5" bass, and forward tweeter, but with bass heavy and sweet treble (as the Grande Utopia does), it's a perfect match.

If some body would have an idea if via the feedback the balance could be changed, let me know. Bruno or Jan-Peter perhaps?

Cheers,

- dan

[lineup]

hi

Op-Amp LM4562 better than AD8620 ??

I say they are BOTH so good that
your choice is more or less a matter of taste.
Or maybe which ones you can find and buy for a good price.

You could make your choice out of practical considerations.
What voltage level you want to use
or what packages you like to work with.

In quality for audio use ... no difference for Audio sounds you will get.
They are both truly in top of
The Super League among Operational Amplifiers!


lineup

[tiefbassuebertr]

Originally Posted by Alfetta87

After our tests with some bulky and expensive amps on top equipment (UcD400 listening vs. Halcro & Gamut - diyAudio), I decided to change the input buffer on my UcD's 400.

I ordered 2 LM4562, and replaced the AD8620 on the UcD boards.

After a few hours of playing, the surprise was big: the amp played better than before!
On the "negative" side, I have to say that the tonal balance changed: less weighty in the LF region, and more brilliant on the upper limit.
Some measurements on and Audio Precision didn't confirm this tendency, so I had to play with different power cords and interconnects, to get the balance right.
On the positive side, there is everything: extreme transparency, warmth and presence in the lower midrange, open but not foreward midrange, extension on both ends. Image remained same as before: stable and detailed. The UcD came damn close(r) the the Halcro DM88, which had a different balance.

I ordered another 2 OpAmps in DIL8, and replaced the ouput amps of my CD player (also AD8620) with the LM's, here the balance was similar but not so pronounced. Together I was afraid that the tonal balance would be pronounced like described before, but it seems after a few days of burning in, it is quite OK. Not suitable for small speakers with a tiny 5" bass, and forward tweeter, but with bass heavy and sweet treble (as the Grande Utopia does), it's a perfect match.

If some body would have an idea if via the feedback the balance could be changed, let me know. Bruno or Jan-Peter perhaps?

Cheers,

- dan

Interesting observations.
Can you upload the schematic of the UcD400?

[Alfetta87]

I don't have the schematic of the UcD400...

The OpAmp is so obvious on the UcD board, no need for a schematic to change it. Anyway, Hypex is selling their UcD HG with the LM4562 OpAmps now.

Cheers,
- dan