Thiel Owners

ronkent is right on!

The 3.5’s recommended power was 40-50* (depending on vintage) to 250 (and even 300 in some circumstances) Watts per channel. Those recommendations were based upon standard 8 Ohm amplifier ratings, with the understanding that with quality ss amplifiers those power numbers would double with the halving of speaker impedances.

So with the Thiel 3.5’s 4 Ohm nominal/ 4 Ohm minimum rating, you’d be well within Thiel’s recommendations for the 3.5’s. With the extra demands the 3.5’s eq makes on amplifiers, I think the extra power would be more welcome with the 3.5’s than with most other speakers with similar sensitivity and impedance loads.

*Interestingly enough the early models had a sensitivity rating of 88 dB and a minimum recommended power of 40 Watts per channel, and with later models Thiel spec’d the sensitivity to 89 dB but also increased the recommended minimum power to 50 Watts per channel.

I've been using my 3.5's with eq on full boost in a moderately large room (15' ceiling peak) and play music at the volumes which were intended, scaled back for domestic room size, in other words; fairly loud on peaks, with an amp capable of 500 Watts (and double that for a couple of minutes at a time) per channel into their 4 Ohm load for many years now, without a hint of problems. Though, I do wish they could play even louder on dynamic peaks with less strain. My 3.5 midranges drivers were rebuilt by Thiel shortly after I purchased them. The previous owner used what IMHO was an underpowered receiver to drive them. Again, no problems since.

Not using the eq would be an anathema for me. Even on steadily loud rock music, I would use the eq at least on the 40 Hz setting. With more lowered tuned 5 string basses and synthesizers being used, there's too much music below 70 Hz where the eq kicks in to compromise without it . That coherent sealed box deep bass is part of the reason I like the 3.5's so much. Without it, I might have kept my old CS 2's. I still prefer the 3.5's  to the later Thiel offerings, except of course for the only other sealed box Thiel's; the CS 5i's. The amplifier requirements for which are the only obstacle towards my ownership.

That  up to 12 dB eq boost might seem a bit extreme, but it is mitigated somewhat but the concurrent rise in impedance.

@thielrules, while I agree with what you've posted, I think there are few things to consider.

The 3.5's as supplied only have single amplifier inputs. What you are suggesting is not possible without modifications to the speakers, which could depreciate their resale value. Sending a separate signal to the eq and then to the woofers, and a separate signal to the rest of the drivers could present a time lag to the woofers compared to the other drivers. Time is after all really what makes speakers like Thiel different and special. Of course in the digital domain it could be compensated for fairly easily, but in the analog domain, well that might take someone like Jim Thiel to figure that out. Also, 6 dB may not be much compared to say what a port rolls off, but it still is rather significant. That 6 dB is per octave, and there are two octaves to cover.