Bob Cordell Workshop at HE 2007

[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.

[Bob Cordell]

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

[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.

[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.

[Bob Cordell]

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

[Bob Cordell]

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

[mlloyd1]

Bob:

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

mlloyd1

[Bob Cordell]

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

[PB2]

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.

[Bob Cordell]

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

Bob