pjorgenunes
New member
Hi all,
I have a FOSI Stereo Amp ZA3 which I liked a lot but, probably due to my B&W 805S being bright and/or difficult to drive in some extent, I found a bit of harshness on top frequency end (noticeable in some recordings).
Having heard about the FOSI V3 Mono AMP and PFFB I decided to give it a try and bought two of them (with two separate 5A power supplies).
I was very pleased about the swap which, although not from night to day - the ZA3 is very very good, it tamed very well most of the harshness on top end (which I think is due to PFFB implementation on the V3 mono).
As I like experimentalism
I decided also to swap the opamps (after two months of experience). After reading some reviews and specs I decided for the TI LME49720NA. Around 4-5€ each and I swapped all three in each amp. The other more expensive Opamps are not an option to me due to cost/expected beneficts (only listening first and if it was a night to day difference).
Firsly I exchanged only the right channel and put my WiiM Ultra (my source) in mono modo, the played with balance to completely left <-> right <-> left (and so on) to compare both. My finding was that the top frequency end gets more "air" and extension without any harshness.
Then I decided for the LME49720NA and swapped the left channel AMP OPAMPS.
Listening in stereo I confirmed the previous findings without any loss in low-mid range and stereo imaging wich is kept.
So, overall, better high end extension and "air".
Note: The opamp that converts unbalanced in balanced signal is not so easy to take out, but is duable with some patience...
Very happy with the FOSI V3 MONO AMP (and with my opamp swap).
My main audio chain is:
WiiM ULTRA -> FOSI V3 MONO AMP -> B&W 805S
I have a FOSI Stereo Amp ZA3 which I liked a lot but, probably due to my B&W 805S being bright and/or difficult to drive in some extent, I found a bit of harshness on top frequency end (noticeable in some recordings).
Having heard about the FOSI V3 Mono AMP and PFFB I decided to give it a try and bought two of them (with two separate 5A power supplies).
I was very pleased about the swap which, although not from night to day - the ZA3 is very very good, it tamed very well most of the harshness on top end (which I think is due to PFFB implementation on the V3 mono).
As I like experimentalism
I decided also to swap the opamps (after two months of experience). After reading some reviews and specs I decided for the TI LME49720NA. Around 4-5€ each and I swapped all three in each amp. The other more expensive Opamps are not an option to me due to cost/expected beneficts (only listening first and if it was a night to day difference).Firsly I exchanged only the right channel and put my WiiM Ultra (my source) in mono modo, the played with balance to completely left <-> right <-> left (and so on) to compare both. My finding was that the top frequency end gets more "air" and extension without any harshness.
Then I decided for the LME49720NA and swapped the left channel AMP OPAMPS.
Listening in stereo I confirmed the previous findings without any loss in low-mid range and stereo imaging wich is kept.
So, overall, better high end extension and "air".
Note: The opamp that converts unbalanced in balanced signal is not so easy to take out, but is duable with some patience...
Very happy with the FOSI V3 MONO AMP (and with my opamp swap).
My main audio chain is:
WiiM ULTRA -> FOSI V3 MONO AMP -> B&W 805S
