The increased efficiency is the first and most obvious difference. The second is the increased sense of ease and detail in the mid-range. I am hearing a lot of new information. The difference between CDs and LPs is even greater than before - with LPs clearly preferable.

The corner positioning and perhaps the use of horns seems to lead to a couple of changes - more air movement and sense of being involved in the sound which is a good thing. The precise imaging I was used to is not really present any more. I feel there's a bit of a hole in the soundstage towards the center. But there's a benefit too - the sweet spot is much bigger. I can sit in many places in the room and still enjoy a balanced sound.

There seems to be a shortage of low bass with the Pi Sevens, but very good and clear and unfussy mid-bass. The Thiels use a passive bass radiator which gave quite a lot of bass - especially if the speakers are anywhere near a corner.

The Thiel cabinets are much more rigid than the Pi Seven bass cab - double or triple thickness baffle, lots of internal bracing, smaller panels. I never felt any vibration of the Thiel cabinet, but I can detect vibration on the front of the Pi. I plan to take the drivers out and beef up the internal bracing.

The treble is clearly less than with the Thiels, but it's clean and sweet. I might investigate a super-tweeter, but we'll see. The integration between the treble and mid-range seems to be perfectly seamless from anything more than a couple of feet away.

One reason the Pis work well for me is that my amp is a Music Reference RM9 tube amp that is not really at its best into very low impedances. The Thiels go below 2 ohms at certain frequencies, which in addition to their low efficiency makes them tough to drive. A transistorized amp was better at the bass, but worse at the mid-range. With the Pis I can get a good overall performance with my tube amp.

Let me know if you have any more specific questions - I'm still learning about the speakers and I'm sure my views will continue to evolve.

My net conclusion is that they were well worth the trouble to build, and a very satisfactory improvement on the Thiels. I wish they were smaller.

Regards,
tim

• Some first impressions...