Thiel 3.5 equalizer advice

JPS made the Golden Flutes which was an upgraded replacement equalizer for the 3.5. These were a significant upgrade to the Thiel unit. They do occasionally come up on the used market. The theory is that as the bass naturally roles off at the lower frequencies, the equalizer boost the same frequencies in order to keep the response flat. Go to the Merlin website and read about the benefit of the Merlin BAM and you will get an idea of what to expect.

I still own a pair and use them in my home theatre as the front channels. I agree with Vernneal's suggestion to just supplement the low end with a sub. The midrange unit on the 3.5 goes quite low, and with it's first order crossover point, it can receive excessive bass especially with the eq in the circuit and set to 20hz. I blew a midrange unit years ago when the eq was in the circuit. Theil replaced the unit at no cost (thank you Theil). Since then, I use them without the eq and have not had a problem since. FYI, I also feel that the eq effects the sound in the mid/highs imparting a slight transistory flavor to the sound.

Thanks for the advice and insights. I enjoy the sound of the speakers as is, but I'm curious to hear the differences with the EQ. A friend who is letting me demo these speakers has one in storage that will be accessible in the Spring.

The midrange units on the 3.5's are paper, while they have a pretty large magnet, and are otherwise well built they do have a tendency to need rebuilding from time to time. Thiel is very good about this. Even if one wanted to use a a sub-woofer I'd recommend using the EQ and using the 40 Hz setting. If your not going to use the EQ, you might as well go with a smaller, cheaper Thiel that will actually go lower than a non-EQ'd 3.5. The EQ does put demands on the amplifier though. I think most of the objections to the EQ are based upon some sort of purist's prejudice. Of course one alternative is to put the EQ in a pre-amps tape loop and depending to the music, one could switch it and out. The only real down side, is an extra set of cables and having the signal passing through the pre-amps circuitry one more time. Once in a while you can find a used 3.5 EQ on e-bay, a much less expensive and less complicated alternative than adding a sub-woofer. The 3.5's EQ's stereo bass will be much better than a cheap sub-woofers.

Like Unsound said, be careful with midranges. I owned a pair of 3.5s and probably went through 4 midranges. The problem is that they use a first order crossover, that while yielding excellent phase linearity, burdens the midrange with having to deal with significant mid/upper bass energy due to the shallow slopes. Thiel was extremely helpful with providing replacement units, even after the speaker was out of warranty.