Interesting Williamson article.. - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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
Reply
 
Thread Tools Search this Thread
Old 7th August 2006, 05:23 PM   #1
diyAudio Member
 
Join Date: Sep 2002
Location: VA
Default Interesting Williamson article..

Don't think this has already been posted here but found this while surfing, appears to be written by an old timer that doesn't like Williamson amps (and trying to push a design of his own).

http://www.cosmos2000.org/audio/william1.htm

Dave
  Reply With Quote
Old 7th August 2006, 06:50 PM   #2
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
As soon as you read about the HF imbalance and distortion from the split-load, you know you're reading a very flawed analysis.

He does manage to mention the one actual mistake in the circuit, an insufficient LF margin because of the two RC couplings with similar time constants. A simple change of one of them by a decade fixes that problem very nicely.
__________________
The more you pay for it, the less inclined you are to doubt it.- George Smiley
  Reply With Quote
Old 7th August 2006, 07:20 PM   #3
Giaime is offline Giaime  Italy
diyAudio Member
 
Giaime's Avatar
 
Join Date: Oct 2004
Send a message via MSN to Giaime
He also says that 6SN7 have inherently low bandwidth...
  Reply With Quote
Old 7th August 2006, 08:01 PM   #4
diyAudio Member
 
Join Date: Jan 2003
Location: Sweden
Hi,

This article has been discussed here several times before and as SY write there are several factual errors the text. For a better understanding of the Williamson amplifier and also to understand what the errors are in the White article I recommend to read the original build description from Wireless World that can be bought as a reprint.

When it comes to correct the insufficient LF margin I believe the best method is to use a phase corrective network between the splitter and the driver as can be seen here http://www.tubetvr.com/Williamson_comp2.pdf compare with the original amplifier here http://www.tubetvr.com/Williamson.pdf

Regards Hans
  Reply With Quote
Old 7th August 2006, 08:07 PM   #5
diyAudio Member
 
Join Date: Sep 2002
Location: VA
Here is the same guy going after Dynaco amps:

http://www.stan-white.org/a_doc_dyna_1.htm

Dave
  Reply With Quote
Old 7th August 2006, 08:11 PM   #6
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Tsk, tsk. More howlers, more promotion for his particular idee fixee, a constant power amp. Unfortunately, speakers are generally designed for constant voltage amps...

There are valid things to criticize about the Dyna design, but he seemed to miss most of them.
__________________
The more you pay for it, the less inclined you are to doubt it.- George Smiley
  Reply With Quote
Old 7th August 2006, 08:13 PM   #7
diyAudio Member
 
Join Date: Jun 2004
Location: Wylie, Texas
He also invented the ideal speaker cone.

And he's an astrophysicist that can explain how the universe began!

He says he's the only living engineer who was there at the beginning of hi-fi.

Sounds like he is the Zen-Master of Audio......
  Reply With Quote
Old 7th August 2006, 08:24 PM   #8
diyAudio Member
 
Join Date: Sep 2002
Location: VA
It would actually be kinda funny if it wasn't kinda pathetic also...

Dave

PS- I'm sorry if that article had been posted here before. I did try 2 searchs here first and didn't discover it..
  Reply With Quote
Old 7th August 2006, 08:25 PM   #9
diyAudio Member
 
Join Date: Jun 2004
Location: Wylie, Texas
PS: please don't take me seriously on that last line!
  Reply With Quote
Old 7th August 2006, 10:03 PM   #10
diyAudio Member
 
Miles Prower's Avatar
 
Join Date: May 2005
Location: USA
Blog Entries: 6
He's got some legitimate complaints, but he's also over reaching quite a bit.

"As soon as you read about the HF imbalance and distortion from the split-load, you know you're reading a very flawed analysis."

With cathodynes, the unequal plate and cathode impedances become a problem that creates distortion when the load impedances become unbalanced, as they will during an overdrive situation where one grid cuts off as the other begins to draw current. Otherwise, no, it's not a prob. The reason I don't care for it is that a cathodyne always seems to be the "weak link" so far as headroom is concerned (unless you supply it with some insane DC Vpp's). Otherwise, from the balance and distortion perspective, there are lots worse phase splitter topologies out there.

" He also says that 6SN7 have inherently low bandwidth... "

Just plain nutz there. He said that this was due to the higher than normal r(p) of the 6SN7. Isn't so: the r(p) of this type is comparable to that of similar triodes: 12AU7 and 6C4. At ~7.0K, it's not all that high. It does, however, seem to have a highish reverse transfer capacitance, but at 4.0pF, it's not really a problem unless your Cmiller is way up there and you're driving from something like a 12AX7A with a very low plate current. Still, that could be solved by using an active load on the 12AX7A to get the plate current up if you have a very limited Vpp.

The 6SN7 was intended to be (amoung other things) an oscillator/buffer tube and/or an astable multivibrator. It could run all the way down to the 10M band with no probs.

"He does manage to mention the one actual mistake in the circuit, an insufficient LF margin because of the two RC couplings with similar time constants. A simple change of one of them by a decade fixes that problem very nicely."

I avoided that problem with one of my designs by using DC coupling as much as possible, and making sure that the one place where a coupling capacitor was unavoidable to make it a big one. A couple of 0.22uF/450Vdc Auricaps aren't all that expensive. Good open loop low frequency response and gNFB that consequently stayed effective made for excellent bass performance.
__________________
There are no foxes in atheistholes
www.dolphin-hsl.com
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Interesting article.. DigitalJunkie Everything Else 4 8th July 2009 10:05 PM
Interesting article on industry vs audiophiles. protos Everything Else 0 18th March 2005 01:06 PM
interesting article bombardon73 Multi-Way 4 16th November 2004 06:42 PM
Interesting article in the last EDN FrankDIY Solid State 1 28th October 2002 12:55 PM


New To Site? Need Help?

All times are GMT. The time now is 10:58 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2