John Curl's Blowtorch preamplifier - Page 661 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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
Closed Thread
 
Thread Tools Search this Thread
Old 15th June 2008, 12:43 PM   #6601
snoopy is offline snoopy  Australia
Banned
 
Join Date: Feb 2006
Location: Melbourne
Default Re: Multiple choice quiz on logic

Quote:
Originally posted by syn08




Which of the above is more than an blank, empty, unsubstantiated statement:

a) PMA's.
b) syn08's.
c) Both.
d) None.
e) Statistically insignificant
f) Everyone is entitled to their own opinion

 
Old 15th June 2008, 01:34 PM   #6602
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally posted by Charles Hansen


Unfortunately, no.

Scott, did you see my post a while back asking you if ADI would be interested in making an IC dedicated to high-end audio?

Yes I did.

Charles, if you mean complimentary JFETs on an IC, that’s never going to happen. We have experimented with it out of curiosity. I think they were P and N but far from truly complimentary. Take PMA’s circuit and compute the headroom it needs to the rails, more than a volt to both rails. Take some of the EC output stages presented in other threads, again several volts of headroom needed. These ideas might be great for audio, but aren’t universally useful. The high end business is far too fickle and fractioned. National put out an “audiophile” version of one of their amps in a TO can (I still think Pease is LHAO) that’s about as far as I can imagine any major player going.

For every John Curl there’s a Tim de Paravicini. He has universal acclaim and Grammy winning recording that many consider one of the best ever made with lots of tubes and transformers BTW. On my last trip to Europe I spotted at least 4 or 5 impressive looking multi-$1000’s phono preamps. So how many John Curls are out there with 40 or 50 worshipful customers? I don’t know why it can’t be more “different” rather than “better” when things are at this level. I’m not the one who’s going to herd the cats. In fact no one is going to do it with a single IC design.
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
 
Old 15th June 2008, 01:49 PM   #6603
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
I just woke up to all this.
I thought that I might carry on with some high level engineering discussions. Of course, everyone is allowed to follow along, and even contribute, if they have anything useful to contribute. The problem is what is 'useful' in a discussion like this.
I recall having a discussion in 1973 with Dr. R.G.Meyer on 3'rd order harmonic distortion cancellation due to local feedback. He gave me about 5 minutes, and then asked me to leave. My final question to him was whether higher order harmonic cancellation was also computed. His answer was no, at the time. Now, 1/3 of a century later, advanced Spice simulations on this website and the earlier work of Baxendall (sp) in 'W.W' gave me the answer I was seeking back then. Did I blame R.G. Meyer (who is the same age as me) for not wanting to me 'shoot the bull' with him? Not really, he was a full professor and I was just a design engineer. He had no need for my input at the time. Later when he did need my input, he was more attentive.
I am most attentive when I see real input on this thread, and will remain so.
 
Old 15th June 2008, 02:15 PM   #6604
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
John, you're probably talking about the fractional Vt degeneration in an output stage? Is there a value that cancels the 7ths but lets a little more 3rd through? PMA a simulation of this would probably suffice.
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
 
Old 15th June 2008, 02:28 PM   #6605
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
No, single device cancellation.
 
Old 15th June 2008, 03:28 PM   #6606
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
The same idea works for an output stage and an "H" bridge input stage. We use it on inputs but the headroom penalty at high output currents makes it not useful in the output stage.

BTW John do you know Bruce Wooley? A fellow Milwaukeean doing well at Stanford. I understand being shunned by the academics from "the other side of the tracks".
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
 
Old 15th June 2008, 04:54 PM   #6607
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Hard to beat class A on the output. Don't know Bruce Wooley, personally, but heard of him. Do you know Dr. David Shreve, of Shreve tone arm fame? Works at Hughes now, but I first met him when he was teaching math in M, WS in 1976.
 
Old 15th June 2008, 05:37 PM   #6608
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Scott, as you probably know, the challenge of output stage distortion minimalization was first done by Barney Oliver in 'Distortion in Complementary-Pair Class-B Amplifiers' back in the early '70's. The problem is that Barney did not care what harmonic was minimized, just so that the THD was lowest, and he even added higher order harmonics in one approach. This was unfortunate, but his article is still useful.
Do you have the ratio for Re vs Ic that minimizes 7th harmonic distortion? That would be interesting to me.
 
Old 15th June 2008, 06:09 PM   #6609
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Hi John,

The THD at 20kHz and 200W of my class-AB amp is below 1ppm, and the 7th harmonic below 0.2ppm. Is that low enough for you?

Cheers,
Edmond.
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
 
Old 15th June 2008, 07:30 PM   #6610
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
What is your OLG -3dB rolloff frequency, and what is the LF loopgain, Edmond?
 

Closed Thread


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



New To Site? Need Help?

All times are GMT. The time now is 09:35 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