square wave testing and slew rate

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
www.hifisonix.com
Joined 2003
Paid Member
Janneman is correct. The amp never 'waits' for a feedback signal to arrive. Remembe r there is a steady state f/back signal. A fast input signal simply modulates this steady state f/back level (ignoring any issue s around slew rate limiting)

In classic LTP+Integrating VAS+Output stage, slew rate is determined primarily by the LTP current and Cdom. High LTP current and low values of Cdom make for high slew rates. Over on the permanent feedbasck thread there is an excellent discussion on this subject. Read Walt Jung's papers on this subject. He makes it clear that high slew rates are important for faithful sonic reproduction. For thse reasons, I like to run my input stage at 10mA with heavy emitter degeneration (150 Ohms or more) and Cdom as low as possible - 22pF. Of course, another option is to go for a CFA topology which greatly oversomes this whole issue.

The length of the signal path has nothing to do with slew rate. I love reading those HiFi mag reviews where the reviewer (non-technical guy usually) goes on about short signal paths and their sonic benits (and here I refer to short physical signal paths, not short electrical paths).
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.