Try to understand

have' · 8th July 2006, 08:50 AM

I have read about the Eico HF-81 amp in the new Stereophile.
The author write that the Eico a very good amp, and it use the
Williamson amplifier circuits .
Can you explain what is the "Williamson amplifier circuits "?
And is this circuit realy so good ?

Many thanks

lndm · 8th July 2006, 11:27 AM

The Williamson style of amp was designed in the '40's, I think. It is a gain stage direct coupled to a split load phase splitter, then to separate common cathode drivers that have a shared cathode resistor. To this point it used 6SN7's throughout. The output stage was originally push pull triode, I think, KT66's with a special custom wound output transformer.

Though this design did use gNFB, it was relatively simplistic for it's time. It had a cult following due to its good sound. Many clones were built, with many different valves and variations but there is supposed to be something magic about the specific original operating conditions.

I have built a reasonable clone of the Williamson. It was my first all valve amplifier. It convinced me that I'd taken a road from which there was no return. Though I go single-ended these days, I have no hesitation in recommending a well built Williamson.

8th July 2006, 08:50 AM	#1
have' diyAudio Member Join Date: Apr 2005 Location: pmr	Try to understand I have read about the Eico HF-81 amp in the new Stereophile. The author write that the Eico a very good amp, and it use the Williamson amplifier circuits . Can you explain what is the "Williamson amplifier circuits "? And is this circuit realy so good ? Many thanks

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
I Don't Understand.	Patrick Bateman	Multi-Way	47	3rd September 2010 10:07 PM
Trying to understand this LPF better	Mike-Toronto	Multi-Way	2	30th May 2009 12:17 AM
I Can't Understand What They're Saying.	Patrick Bateman	Multi-Way	6	27th February 2009 08:40 PM
Please Help Me Understand This...	RobAche	Multi-Way	3	9th December 2003 08:44 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

8th July 2006, 11:27 AM	#2
lndm diyAudio Member Join Date: Mar 2006 Location: nsw	The Williamson style of amp was designed in the '40's, I think. It is a gain stage direct coupled to a split load phase splitter, then to separate common cathode drivers that have a shared cathode resistor. To this point it used 6SN7's throughout. The output stage was originally push pull triode, I think, KT66's with a special custom wound output transformer. Though this design did use gNFB, it was relatively simplistic for it's time. It had a cult following due to its good sound. Many clones were built, with many different valves and variations but there is supposed to be something magic about the specific original operating conditions. I have built a reasonable clone of the Williamson. It was my first all valve amplifier. It convinced me that I'd taken a road from which there was no return. Though I go single-ended these days, I have no hesitation in recommending a well built Williamson.

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