Bob Cordell Workshop at HE 2007 - 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
Reply
 
Thread Tools Search this Thread
Old 13th May 2007, 01:06 PM   #1
al2002 is offline al2002  India
diyAudio Member
 
al2002's Avatar
 
Join Date: Dec 2003
Location: USA
Default Bob Cordell Workshop at HE 2007

At the HE 2007 show Bob Cordell's workshop - Room 1627 should you wish to go - was by far the most interesting presentation. This alone was worth the price of admission. It was very similar to his Rocky Mountain workshop, details of which can be seen on his site. It confirmed, for the nth time, the minor role electronics play in determining the overall sound of a hi-fi system in a room.

Bob had a working version of his super gainclone (3886 chip amp) and it measured under 0.01% THD at 50 W out at 20 kHz. Not bad for a 3 buck chip.
  Reply With Quote
Old 14th May 2007, 05:25 PM   #2
diyAudio Member
 
Join Date: Sep 2006
Default Re: Bob Cordell Workshop at HE 2007

Quote:
Originally posted by al2002
At the HE 2007 show Bob Cordell's workshop - Room 1627 should you wish to go - was by far the most interesting presentation. This alone was worth the price of admission. It was very similar to his Rocky Mountain workshop, details of which can be seen on his site. It confirmed, for the nth time, the minor role electronics play in determining the overall sound of a hi-fi system in a room.

Bob had a working version of his super gainclone (3886 chip amp) and it measured under 0.01% THD at 50 W out at 20 kHz. Not bad for a 3 buck chip.

Thank you for those very kind words! The workshops that Peter Smith, Darren Kuzma and I presented were a lot of fun and were successful beyond our wildest hopes.

Not only were they well-attended, but the particpants really asked great questions and showed a true thirst for information. We got great questions from both newbies and those who were already well-experienced in the industry. The show was a lot of fun and overall attendance was great, with Saturday being really packed. The only downside to that was that the elevators were pretty slow as a result.

Our workshops were jointly sponsored by Stereophile Magazine and Ray Kimber, without whose kind support none of this would have been possible. John Atkinson loaned us his own Ayre CD/SACD player for the show - it is a gorgeous, beautiful sounding machine.

Bob
  Reply With Quote
Old 15th May 2007, 02:11 AM   #3
PB2 is offline PB2  United States
diyAudio Member
 
PB2's Avatar
 
Join Date: Sep 2004
Location: North East
Blog Entries: 1
It was a pleasure to meet Bob in person, experience the demos, and to discuss amplifier and speaker design.

I did the tube versus transistor amp comparision and got to throw the switch. I could pick out the tube amp in general by listening and concentrating on the bass. The midrange and high end was also cleaner with the solid state amp. I have my own A/B switch so I've done this sort of experiment before. It has been many years since I've compared amps, I mostly use mine to compare speakers.

The differences were subtle and I suggested roughly matching output impedance by adding a resistor in series with the solid state amp. I believe that this would make it nearly impossible to tell a difference as long as the amps are not allowed to clip.

Thanks to Bob and your co-hosts, your room alone made it worth going to the show.

Pete B.
  Reply With Quote
Old 15th May 2007, 02:18 AM   #4
PB2 is offline PB2  United States
diyAudio Member
 
PB2's Avatar
 
Join Date: Sep 2004
Location: North East
Blog Entries: 1
Default Vifa D26NC55 Tweeter

I mentioned the low cost Vifa D26NC55 tweeter as having a small face plate which allows close mounting. It is a remarkable and somewhat unusual tweeter with neo magnets and a heatsink. The performance is outstanding in many areas as can be seen in Zaph's tests. Look at the CSD plot for example:
http://www.zaphaudio.com/tweetermishmash/csd.html

It has been discontinued by Vifa, do they not even realize what they had?

http://www.riviera-acoustics.com/cat...6nc55-06_l.gif

Pete B.
  Reply With Quote
Old 15th May 2007, 03:51 AM   #5
diyAudio Member
 
Join Date: Sep 2006
Quote:
Originally posted by PB2
It was a pleasure to meet Bob in person, experience the demos, and to discuss amplifier and speaker design.

I did the tube versus transistor amp comparision and got to throw the switch. I could pick out the tube amp in general by listening and concentrating on the bass. The midrange and high end was also cleaner with the solid state amp. I have my own A/B switch so I've done this sort of experiment before. It has been many years since I've compared amps, I mostly use mine to compare speakers.

The differences were subtle and I suggested roughly matching output impedance by adding a resistor in series with the solid state amp. I believe that this would make it nearly impossible to tell a difference as long as the amps are not allowed to clip.

Thanks to Bob and your co-hosts, your room alone made it worth going to the show.

Pete B.

Hi Pete,

I'm glad you could come, and thanks for the kind words. I remember your comment about the resistor. I also believe this to be the case. I actually added about 0.2 to 0.3 ohm in the output of the Super Gain Clone when I built it with this very same thing in mind. This, together with the soft clip circuit, I reasoned, would make it sound more like a tube amp. Bob Carver also espoused this at one time as well. I wish we had had time to compare it against the tube amp at the workshops. Time really flew by.

Best regards,
Bob
  Reply With Quote
Old 15th May 2007, 05:08 PM   #6
diyAudio Member
 
Join Date: Sep 2006
Default Re: Vifa D26NC55 Tweeter

Quote:
Originally posted by PB2
I mentioned the low cost Vifa D26NC55 tweeter as having a small face plate which allows close mounting. It is a remarkable and somewhat unusual tweeter with neo magnets and a heatsink. The performance is outstanding in many areas as can be seen in Zaph's tests. Look at the CSD plot for example:
http://www.zaphaudio.com/tweetermishmash/csd.html

It has been discontinued by Vifa, do they not even realize what they had?

http://www.riviera-acoustics.com/cat...6nc55-06_l.gif

Pete B.

Hi Pete,

Thanks for mentioning that tweeter. I really like tweeters with small faceplates so I can get them close to the midrange (although some of the small tweeters don't go as low as I'd like). From talking to some of the people at the HE2007 show, it sounds like the Tympany takeover of Vifa has been a bit of a train wreck. Darned shame! Sorry to be off-topic here.

Bob
  Reply With Quote
Old 15th May 2007, 06:12 PM   #7
mlloyd1 is offline mlloyd1  United States
diyAudio Member
 
mlloyd1's Avatar
 
Join Date: Feb 2001
Location: illinois
Bob:

Ever plan to have one of these shows in the midwest?

mlloyd1
  Reply With Quote
Old 15th May 2007, 06:42 PM   #8
diyAudio Member
 
Join Date: Sep 2006
Quote:
Originally posted by mlloyd1
Bob:

Ever plan to have one of these shows in the midwest?

mlloyd1

We did RMAF last October in Denver, but that may not be considered midwest, and it was a pretty long trek from here on the East Coast. If an opportunity comes up in, say, Chicago, we might be able to do that.

Thanks for your interest.

Bob
  Reply With Quote
Old 17th May 2007, 01:43 AM   #9
PB2 is offline PB2  United States
diyAudio Member
 
PB2's Avatar
 
Join Date: Sep 2004
Location: North East
Blog Entries: 1
Default Re: Re: Vifa D26NC55 Tweeter

Quote:
Originally posted by Bob Cordell



Hi Pete,

Thanks for mentioning that tweeter. I really like tweeters with small faceplates so I can get them close to the midrange (although some of the small tweeters don't go as low as I'd like). From talking to some of the people at the HE2007 show, it sounds like the Tympany takeover of Vifa has been a bit of a train wreck. Darned shame! Sorry to be off-topic here.

Bob
It seems Tympany had to reduce the combined lines of Vifa and Peerless but it seems that the D26NC55 should have been retained. They probably needed a customer for it to keep it in production, don't know for sure.

I don't think this is off topic, since we did discuss your active speaker at the show.

Pete B.
  Reply With Quote
Old 17th May 2007, 02:35 PM   #10
diyAudio Member
 
Join Date: Sep 2006
Default Peak Power Requirements

Peter Smith has an article on the peak power workshop in the latest edition of AudioXpress that just came out.

Bob
  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
Anyone Going to the AES 2007 Convention? PB2 Everything Else 0 7th October 2007 01:11 AM
Any news from CES 2007 yet? slogan2112 Multi-Way 19 17th January 2007 06:14 PM


New To Site? Need Help?

All times are GMT. The time now is 02:45 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