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 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.
al2002 said:
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
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.
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.
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/catalog/images/vifa/d26nc55-06_l.gif
Pete B.
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/catalog/images/vifa/d26nc55-06_l.gif
Pete B.
PB2 said:
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
Re: Vifa D26NC55 Tweeter
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
PB2 said:
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
Re: Re: Vifa D26NC55 Tweeter
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 said:
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.
HE2007 Workshop Show Report Posted
I have posted a Show Report for the HE2007 audiophile Listening and Measurement workshops we presented on my website at www.cordellaudio.com. Each workshop is described in detail and some pictures are provided as well.
The six workshops were as follows:
Amplifier Listening Comparison
Loudspeaker Listening Comparison
The Peak Power Demands of Well-recorded Music
Amplifier Measurement Clinic
Speaker Measurement Clinic
Active Loudspeakers - an Example
Once again I want to thank Stereophile Magazine and Ray Kimber for their generosity in sponsoring these workshops.
Cheers!
Bob
I have posted a Show Report for the HE2007 audiophile Listening and Measurement workshops we presented on my website at www.cordellaudio.com. Each workshop is described in detail and some pictures are provided as well.
The six workshops were as follows:
Amplifier Listening Comparison
Loudspeaker Listening Comparison
The Peak Power Demands of Well-recorded Music
Amplifier Measurement Clinic
Speaker Measurement Clinic
Active Loudspeakers - an Example
Once again I want to thank Stereophile Magazine and Ray Kimber for their generosity in sponsoring these workshops.
Cheers!
Bob
Hi Bob,
Can you tell us more about the speakers you had on show?
Any plans to release details for DIY builders to have a go?
Tasty looking WWWWMT and 8 (or 10"?) 3-way, as shown in the 1st picture on your HE07 show report.
http://www.cordellaudio.com/he2007/HE2007-1.jpg
Can you tell us more about the speakers you had on show?
Any plans to release details for DIY builders to have a go?
Tasty looking WWWWMT and 8 (or 10"?) 3-way, as shown in the 1st picture on your HE07 show report.
http://www.cordellaudio.com/he2007/HE2007-1.jpg
tktran303 said:
The WWWWMT is a 3.5-way active loudspeaker dubbed the Athena. It is described in some detail on my website at www.cordellaudio.com. There is not enough detail there to make it a DIY project, as it was an extremely challenging design. Each cabinet has four 125 watt MOSFET power amplifiers inside it. One for the tweeter, one for the mid, and one for each of the two pairs of woofers. The active crossover and EQSS equalizer are also inside the cabinet. The unit can be fed either a line-level signal or a speaker-level signal. In the latter case, the unit provides an internal 8-ohm dummy load at the speaker terminals.
The three-way was done by Peter Smith. Details of his speakers are at www.helarc.com. I don't know if the details of that speaker are up on his site yet.
Cheers,
Bob
Thanks for your reply Bob,
Pjay had alluded to the 3-way that he had been working on. I didn't know they were finished.
Were these the 2 speakers used in the Loudspeaker Listening Comparison workshop?
Compared to the other reports on the HE07 workshops, this one was very brief, and I didn't quite get the take-home-messages.
Different loudspeakers sound different?
What is right and what is wrong is often hard to define?
Different tracks can highlight differences better that others?
regards,
Thanh.
Pjay had alluded to the 3-way that he had been working on. I didn't know they were finished.
Were these the 2 speakers used in the Loudspeaker Listening Comparison workshop?
Compared to the other reports on the HE07 workshops, this one was very brief, and I didn't quite get the take-home-messages.
Different loudspeakers sound different?
What is right and what is wrong is often hard to define?
Different tracks can highlight differences better that others?
regards,
Thanh.
tktran303 said:
Yes, these were the two sets of loudspeakers used in the loudspeaker listening comparisons, at least at the beginning of the show on Friday. Saturday morning we were making some changes and setup adjustments and I somehow managed to blow Peter's tweeter in one of his three-ways. So thereafter, we used his two-ways that had been previously used at RMAF.
I'm sorry that the reports were brief. Are you sure that you drilled down to the full reports on my website at www.cordellaudio.com under the HE2007 tab? Not just the abstracts. The show report was pretty much limited to the workshops, as we didn't get much chance to see a lot of the rest of the show.
Anyway, the takeaway on the loudspeaker comparison was that loudspeakers not only sound different, but they can influence how you perceive the sound of the other one. We also noticed that the ear-brain seems to adjust, and that sometimes after a switch from one speaker to another, the new speaker sounds better after some time has passed. There seems to be an awful lot of psychology going on there.
It was also very true that different music and tracks can make one or the other speaker more appealing, so the choice of speaker may depend a lot on the kind of music you are listening to. At the same time, we found it is very hard to make generalizations.
We also observed that level matching is very important in listening comparisons, but noted that level matching is not that easy to define when the two speakers being compared are inevitably voiced a bit differently.
Cheers,
Bob
Bob Cordell said:
Bob Cordell said:
al2002 said:
hi Bob.
I actually got a hold of a fairly detailed description of the Gainclone system
you & your friends used in Bob Cordell Workshop at HE 2007 - Room 1627.
... don't ask me how ... there is not much detail in your homepage
... but in these internet times we live in, there are many ways ...
I have not the suberb speakers 3.5-way active loudspeaker Athena by Peter Smith as you used.
But the LM3886 curcuit setup, including 0R22 output resistors, is a pretty accurate copy of your Gainclone version.
I can say even with my own more normal 'good audio speakers' & in my livingroom,
this amplifier performs beyond most I've heard
And I can only agree with al2002:
Lineup - regars
-----------------------------------
Appendix. References.
LM3886 - High-Performance 68W Audio Power Amplifier
http://www.national.com/ds/LM/LM3886.pdf
lineup said:
hi Bob.
I actually got a hold of a fairly detailed description of the Gainclone system
you & your friends used in Bob Cordell Workshop at HE 2007 - Room 1627.
... don't ask me how ... there is not much detail in your homepage
... but in these internet times we live in, there are many ways ...
I have not the suberb speakers 3.5-way active loudspeaker Athena by Peter Smith as you used.
But the LM3886 curcuit setup, including 0R22 output resistors, is a pretty accurate copy of your Gainclone version.
I can say even with my own more normal 'good audio speakers' & in my livingroom,
this amplifier performs beyond most I've heard
And I can only agree with al2002:
Lineup - regars
-----------------------------------
Appendix. References.
LM3886 - High-Performance 68W Audio Power Amplifier
http://www.national.com/ds/LM/LM3886.pdf
Hi lineup,
Thanks for your kind words.
Indeed I have been remiss in putting up more info on the Super Gain Clone on my web site. For that I apologize and know that I need to put up more stuff on the site.
I believe that a friend of mine will be making a kit version of the SGC available this year.
The Athena active loudspeaker systems were actually done by me. Each has four fully discrete 125-watt MOSFET power amplifiers built into the cabinet. Peter did the passive three-way speakers we employed at HE2007.
Cheers,
Bob
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