Re: Headphone Outputs: Build-Out vs. No Build-Out
Posted: Fri Feb 03, 2012 3:02 pm
Yes, Dennis Bohn, Chief Technology Officer.
It was good to hear from him.
It was good to hear from him.
https://www.proaudiodesignforum.com/forum/php/
https://www.proaudiodesignforum.com/forum/php/viewtopic.php?t=497
I sure appreciate Dennis' response and his allowing me to publish it.Hi Wayne,
We've finally had a chance to look this over and get back to you, but first a little history:
The HC 6 was Rane's first product originally designed and first manufactured in in 1982. Amazingly it is still a good seller -- 30 years later.
Over this time the circuit has been revised several times due to many reasons. Some of these are due to vendors discontinuing parts, due to going from single sided through-hole components to surface mount, etc.
Each revision comes with its own tweaks.
In this case it is one of circuit stability due to layout. Adding R8 close to the positive input works with the input capacitance to create a high frequency pole that creates extra stability. Also over the years we have changed op amp types. Some are more stable than others. It is just a simple way to make things less squirrelly at high frequencies, plus adds a bit of RFI filtering as well.
Hope this helps explain the mystery.
Thanks for the inquiry.
Dennis Bohn
CTO
Rane Corporation