The mu-amp revisited

tca · 6th October 2011, 01:57 PM

One of the most famous pre-amps for guitar use is the mu-amp. The guitar version has been popularized by Jack Orman which he dubbed mini-booster. This circuit was inspired on the ultra high gain audio amplifier from the National Semi FET Circuit applications.

As strange as this may seem the calculations for studying this circuit are not present in most of the text books of electronics (I've checked a few) and I find the circuit very intriguing. The valve grandfather of this circuit is the SRPP. Theres another page that deals with the topic but the explanation does not satisfies me.

The only way that I've found to study this circuit is to include a load in the schematic otherwise the calculations do not math up (the link for the SRRP clearly shows thats the way to go).

Any comments or suggestions how to understand this circuit.

Cheers.

kenpeter · 6th October 2011, 03:02 PM

You can mathematically compute Mu for any operating point of a JFET.
But because this is highly variable, and not based upon intrinsic feedback
from the channel voltage, its not really "Mu" in the Triode or SIT sense.

This amp is based upon Gm.

6th October 2011, 01:57 PM	#1
tca diyAudio Member Join Date: Jan 2011 Location: Lisboa	The mu-amp revisited One of the most famous pre-amps for guitar use is the mu-amp. The guitar version has been popularized by Jack Orman which he dubbed mini-booster. This circuit was inspired on the ultra high gain audio amplifier from the National Semi FET Circuit applications. As strange as this may seem the calculations for studying this circuit are not present in most of the text books of electronics (I've checked a few) and I find the circuit very intriguing. The valve grandfather of this circuit is the SRPP. Theres another page that deals with the topic but the explanation does not satisfies me. The only way that I've found to study this circuit is to include a load in the schematic otherwise the calculations do not math up (the link for the SRRP clearly shows thats the way to go). Any comments or suggestions how to understand this circuit. Cheers.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
YAP power amp revisited, now at v2.1	syn08	Solid State	195	29th September 2010 07:22 PM
6N1P & SV83 mu stage driving 845?	dr.strangelove3	Tubes / Valves	19	8th January 2007 08:11 PM
6AQ5A guitar amp revisited	Trout	Tubes / Valves	13	23rd February 2005 07:52 PM
Zen Revisited Vs Anthony Holton A/B amp	FullThrottleRic	Pass Labs	20	27th May 2001 01:29 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

6th October 2011, 03:02 PM	#2
kenpeter diyAudio Member Join Date: Nov 2007 Location: Dallas	You can mathematically compute Mu for any operating point of a JFET. But because this is highly variable, and not based upon intrinsic feedback from the channel voltage, its not really "Mu" in the Triode or SIT sense. This amp is based upon Gm.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)