8 channels of AD797 build thread

[ricardo]

so do you think i don't need to worry about noise? sg-acoustics schematic won't make a major difference in sound in my AD797 circuit?

The biggest change in sound/THD/noise bla bla will be cos you've introduced a transformer.  A 1:2 transformer would sorta get the noise back to THAT1510/12 level.

 

[hazel]

so do you think i don't need to worry about noise? sg-acoustics schematic won't make a major difference in sound in my AD797 circuit?

The biggest change in sound/THD/noise bla bla will be cos you've introduced a transformer.  A 1:2 transformer would sorta get the noise back to THAT1510/12 level.

Thanks for answering Ricardo

So a 1:2 transformer would easily handle ribbons and make condenser mics 3dB quieter but, do you think is worth the improvement/cost of 8 transformers?

 

[ricardo]

So a 1:2 transformer would easily handle ribbons and make condenser mics 3dB quieter but, do you think is worth the improvement/cost of 8 transformers?

No ...

... unless you have a Coles 4038 or Shure SM7.  Most condensors are so high output that any decent preamp will do.  It's low output ribbons & dynamics where you are after every dB of noise improvement.

And even then, something like a Cloudlifter is a lot cheaper than loadsa good transformers.  But beware, there are a lot of Cloudlifter type products which are cr*p.

 

[hazel]

And even then, something like a Cloudlifter is a lot cheaper than loadsa good transformers.  But beware, there are a lot of Cloudlifter type products which are cr*p.

I know, recently got a Cloudlifter CL-2 from an European big name audio gear store and sounded bad and ground issues, contacted Cl**d Mics and sent back my faulty unit (was a 1st edition with known issues) and got a brand new one, works like a charm!

So there's nothing to worry about AD797, in a few weeks i'll record some tracks with THAT 1512, AD797 and Y*M*HA PM5D to compare

 

[abbey road d enfer]

Do you think there's space to upgrades or mods in AD797 circuit? i was thinking about http://www.sg-acoustics.ch/analogue_audio/microphone_preamplifiers/pdf/G_r1.pdf. Basically the same but with 1:2 input transformer. What do you think?

Although the 1:2 xfmr improves adaptation between source Z and optimum noise, there is a basic flaw in this implementation (at least in terms of noise optimization). Using two opamps degrades the input noise by 3dB compared to a single one.
If you go the xfmr way, there are many single-opamp implementation that will perform within a fraction of dB to the theoretical minimum. Check the SSL4k.

 

[hazel]

Although the 1:2 xfmr improves adaptation between source Z and optimum noise, there is a basic flaw in this implementation (at least in terms of noise optimization). Using two opamps degrades the input noise by 3dB compared to a single one.
If you go the xfmr way, there are many single-opamp implementation that will perform within a fraction of dB to the theoretical minimum. Check the SSL4k.

Thanks for answering abbey

As stated above i'll pass on xfmr by now, only issue would be using ribbons due to impedance and condenser mics on quiet sources but is not my case as i record loud sources and use Cloudlifter for ribbons and dynamic mics.

I'll also record some quiet tracks using both THAT1512 and AD797