Thiel Owners

@xyzsantabarbara, Though Thiel Audio is usually better than most at posting their specs, I think you'll find the following interesting:

https://www.stereophile.com/content/thiel-cs37-loudspeaker-
specifications

https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements

Whether it's due to different measuring techniques or rounding to standard numerations, I think the 4 Ohm nominal rating is a bit off. The Stereophile measurements suggest a low of 2.4 Ohms and the graph looks more like a nominal 3 Ohm rating to me. And with a difficult phase angle to boot. I'd suggest working from that 2.4 Ohm minimum impedance when gauging for appropriate amplification.

@unsound I saw your prior post on this and do have some concern that the amp may not work. Not a big deal if it does not, the CS3.7 is not going anywhere nor is the Benchmark stack. I plan on setting up 2 rooms once things get back to normal.

The Magico A3 speaker I demoed at a store with my old AHB2 sounded closed in with a single AHB2. I actually sold it after that demo since I was thinking I was going to get the Luxman. Though that changed when I bought the HPA4 and then re-purchased the AHB2.

I will find out soon enough. Unfortunately I do not have funds available to buy a second AHB2 in the short term.

BTW - Did you read the Benchmark designers comments on the links I posted above?

https://forum.audiogon.com/discussions/running-benchmark-ahb2-in-bridged-mode-and-4-ohm-speaker/post...

This is his profile on A’gon.
https://forum.audiogon.com/users/gearbuilder

Unsound - I agree that the proper rating for the 3.7 would be 2.5 ohms. Nominal impedance is by convention stated at or near the minimus after the bass anomalies. If that trough is deep and steep the rating can be upped a little, but the 3.7 does not bounce back and indeed stays below 3 ohms to 500 herz, where lots of power is required for mid-bass output.
I find Jim's adherence to low impedances misguided and limiting. Not many amps perform well into such a low impedance.

Regarding the cracked concrete baffle. The chicken's way out (easy and little danger) is to smear concrete caulk on the inside to stop the airflow. Then dribble thin epoxy or cyanoacrylate into the crack from the front and either finish the show face or not to cosmetic taste.

Like ultra-low impedance, I judge the concrete baffle to be an inadequate solution. It was changed to a stone x polyester substitute, which required considerable ventilation of fumes - the joys of manufacturing. I've mentioned my preference for the Hydrostone solution that ended up in Hales counterparts. 

YYZ - what a system! Thanks for chiming in. I landed on Benchmark for my use and love it. thielrules is correct that low impedance loads are harder to drive when bridged. John Siau, the designer. evaluated all Thiel performance curves and chose only the early models plus the 7.2 as suitable for mono. But so much depends on particulars. My (odd) room is effectively fairly large; I listen in the 85dB range max (except for short bursts of stress testing.) The AHB-2 has excellent protection and excellent LED monitoring. I overdrive far more in stereo mode than mono on the PowerPoint, SCS4, CS2.2, 3.5 and 3.6 (all I have.) Additionally, the internal protection is so good and so fast that there is little if any danger of a distorted signal passing through. They are a different type of amp entirely. I land on bridged mono to stay out of clipping almost entirely.

Awhile back some of us on this forum (perhaps behind the curtain, I don't remember) compared AHB-2s in mono vs stereo and agreed that stereo sounds somehow purer/more delicate - subtle difference. John Siau is convinced that we are hearing the halving of damping factor in mono and that halving the cable length would make them 'sonically identical'. I'm skeptical of identical, but he has a valid point.

Today's tri-amping experiment hasn't lifted off, but I hope to be ready for Natasha's visit tomorrow afternoon. We'll be comparing different amp setups through the outboard crossover. I'll report after I've gathered some experience.