Thiel Owners

@unsound,Yikes -- I pasted the specs for the DMA-300 into the DMA-400 slot. To amend:

Power Output DMA-400 (continuous)

@ 8 ohms - 350 Watts RMS

 @ 4 ohms - 560 Watts RMS

@ 2 ohms - 705 Watts RMS

Output Current

90 Amps peak

Frequency Response

ą0.1 dB, DC-150 KHz

ą1 dB, DC-1 MHz

ą3 dB, DC-1.8 MHz

Thiel  actually checked out worse on Stereophile specs, going down to only 26 kHZ, not 22 as stated in my manual (weird), DMA-300 is same as quoted. Alright! Sorry about the confusion.

@tmsrdg, Thiel recommends as little as 100 Watts for the 3.7’s. IMHO, the 200 minimum you suggested might work better. As I’ve suggested in the past, those are standard 8 Ohm power ratings that should be doubled down with actual minimum impedance.

@unsound
Is there a technical reason that the "double down" ratio keeps popping up?For  instance, the DMA_400 listed above does not do this in sequence from 8 ohms to 4 to 2, but as I run the numbers it seems more than adequate. Is that right, or does "doubling down" refer to an important harmonic ratio needed here? Also, the minimum impedence of the 3.7 is 2.8 ohms, so perhaps we need to consider that the DMA-400 does indeed double from the 8 ohm rating to the 2 ohm. Thanks again for any thoughts on this.

The 2.8 minimum impedance are manufacturer specs.  There have been independent measurements (e.g.  https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements) indicating it is either 2.4 or 2.3.  I've had different amps on my 3.7s including a Bryston 4BSST, 14BSST, Modwright KWA 150SE and the last two have been Class D (using a Ric Schultz EVS 1200 now).  When my friend worked at a hifi shop many moons ago, I helped deliver a bunch of things and often Thiel was paired with Levinson (when I had my 7.2s I had a Proceed HPA).  Like anything else it is dependent one's room and listening habits (music preferences and loudness level).  My main room in the old place (I started with 2.3s, then 7.2s and then 3.7s) was huge (something like 7,000 cubic feet that opened into other spaces and when I had an old Bryston 4BST (not the SST), I actually drove it into momentary clipping.  The 14BSST (15 amp version) could not handle the impedance (would go into thermal shutdown during music or movies which where somewhat intense) and I ended up building a custom amp stand with fans (which solved the issue).  The 3BSST wasn't as bad a load but would get the 14BSST heat sinks hot enough to burn one's hand.  The Modwright amp ran a hair cooler (and the heatsinks where inside the case).  The room in the new place is big but not as big as the old place and the Modwright did a bit better but not as well as either of the Class Ds I've used (which bested it in every way and it still shocks me to touch the amp case and hardly feel anything warmth.

tmsdrg - I am one of the culprits of touting the necessity to double power with halving impedance. My point was more academic than of real consequencel. If an amp doesn't double its power into half impedance, then it is by definition current limited. BUT, as has been pointed out here previously, that point of art is of no real importance as long as there is enough current to deliver to the load. So, doubling is not a technical necessity to drive Thiels, but that sense of anemic bass, slow transients, etc. is symptomatic of running out of current capacity. The 3.7 is about twice the efficiency as many previous Thiels, so the problem becomes less of an issue than before.