Thiel Owners


Guys-

I just scored a sweet pair of CS 2.4SE loudspeakers. Anyone else currently or previously owned this model?
Owners of the CS 2.4 or CS 2.7 are free to chime in as well. Thiel are excellent w/ both tubed or solid-state gear!

Keep me posted & Happy Listening!
128x128jafant
Have you guys (Andy, Beetle, Holco or Tom) found this problematic for your personal system power amps to drive? As I understand it, this is correlated in drops between 4 Ohms down to 2 Ohms across much of the speakers' frequencies. 3 Ohm nominal.

The impedance of a speaker can be a bit complicated (but it doesn't have to be).  The other side is how the amp drives the speakers if the amp is a no-feedback or feedback design.

In general, the higher the impedance is the better but that statement is a bit overly simplified since higher at some frequencies may not be good.  In most speakers, the impedance is lowest at low freq. around 100 - 200 hz and rises toward the higher freq.  The low freq is where most amp will have issue if it stays too low.  I think the impedance of 3ohm or above is probably OK, but below 3ohm, some low power amp probably will have problem.  At high frequencies, low impedance is usually not an issue since high frequencies do not demand as much current vs. low freq.

As the freq. rises higher, you probably don't want impedance to get too high (due to inductance rising) which will result in treble harshness.  In some speakers, there is an "impedance correction network" to reduce the rising impedance so that it won't be a problem for tube amplifiers.  So this is where high impedance is not good either.  

As for impedance angle, it is mostly negative (capacitive) at low freq. and gets more positive (inductance) at higher frequencies.  As long as there is not excessive swing from negative to positive, it should be fine.  In general, you don't want the phase angle excessive negative at low frequencies and excessively positive at high frequencies.  Too negative angle at low freq. will be hard to amp to drive.  Too positive at high frequencies may result in treble harshness.  In general, capacitive load demands more current and reduces dynamic, whereas inductive load causes high frequencies issue.  

The other side is the amp design.  Some amp are design with no feedback and some with feedback.  Most people agree that no feedback is better sounding vs. feedback.  But amp with no feedback are more sensitive to speaker impedance swing so it is a trade off.  Interestingly enough, most low cost amplifiers are designed with relatively high feedback because it costs a lot more to design a good amp with no feedback.  Tube amps tend to be most sensitive to impedance since most of them are designed with very little feedback or no feedback at all and exacerbated because tubes usually don't have a lot of drive current. 

For those who are interested in feedback vs. no feedback argument, there is a good article from PASS lab that I included the link below:
http://www.firstwatt.com/pdf/art_dist_fdbk.pdf

tomthielThank You for addressing my query on right phase angles. I know that all of you guys are occupied with work and various other activities/interests.Looking forward to other contributors chiming in on their power amps outside of the Ayre, Classe', Krell, Mark Levinson and Pass Labs owners.Hope you are well today and enjoying your Hot Rod garage.
Happy Listening!
holco,Thank You for citing the specs of your Audio GD power amp. Those ratings are incredible! With those figures, I have no doubt about under-driving your CS 2.4 loudspeakers. I have really enjoyed reading about your cross-over upgrade project as well. Glad you are a member of the Panel.
Happy Listening!
andy2Thank You for providing your expertise as well. Agreed, amp design as it addresses feedback vs no-feedback is pivotal for our speakers. I try nt to get too tied up in the manufacturer specs as well. Reading across other Audio forum threads, other Thiel owners are enjoying some of the lesser known power amps and/or integrated amps with success. Along the lines of designers not citing 2 ohm power ratings, I also find, peak current delivery in amperes (A) not reported.  John Atkinson of Stereophile fame and Paul Miller of HiFi News & Record Review fame do a pretty good job of reporting pertinent figures/ratings as discussed here.
Happy Listening!
On another related thread, desmond888 , is working on a cross-over project upgrade as well. You guys check out his progress as your schedules allow.  Very cool to have so many DIY guys making improvements and upgrades on an already Legendary design.
Happy Listening!