Hallo, I am new on this site - in fact only just over a year into being a broadband user. I have however been in audio both as an amatuer since I was 16, and also in professional capacities, and now I need some help.\r\nIn my teens I built several speakers; notably a paralline with a Lowther unit, and at 21 bought a pair of Tannoy Lancaster Golds which I kept until '84.\r\nAt this time I saw an ad. for a pair of ESS Monitors, and after taking a loan and selling my Tannoys, rebuilt them to the latest Spec. at that time.\r\nI then lost my way and sold them, purchasing a pair of professional monitors made in Britain, the name of which is an anagram of one of the two popular domestic pets. In all, I went through 4 pairs of these active monitors, never satisfied, and finally rebuilding the last '100s' in ;97 and spending £1000 in so doing.\r\nStill dissatisfied, I then saw an ad. in Hi-Fi News for a pair of ESS AMT 1Cs, and bought them.\r\nThis time I really took them apart in an attempt to maximise them; new woofers, diaphragms, crossovers from Germany, put 53 wood braces in the cabinets, soaked them in polyurethane varnish, lined them with rubber carpet underlay, and veneered them with EDPA rubber.\r\nFor a few years I got more out of my music, but although they were revealing, my technical side questioned their accuracy. I gradually realised that the frequency balance was wrong; the bass was excessive and underdamped, and the middle compressed (BL factor), transients not being well represented.\r\nEighteen months ago I bought a pair of BBC\/Rogers woofers from the BBC flagship the LS 5\/8, and substituted these in the system with an approximate Xover coil change to get an idea of their performance. They are much faster woofers, and from a design using the same Xover frequency as the new ESS Xover, 1.8kHz, and it seemed to work well.\r\nLast year I re-aligned the bass for this woofer, (passive mass), changed the stuffing arrangment, and padded the frame of the woofer to reduce resonance and reflections, and in January replaced the series inductor for the woofer with a calculated value, based on the BBC's voltage curve for the unit. The calculated value was 3.872mH, and I put in a Mundorf 3.9mH foil coil which has a series resistance of only half an ohm. The response seems right, the bass very fast and taught, and my friends think that the response is right in the bass and mid, but they question the Heil, which they criticise, and which is using a 4th order Butterworth Xover.\r\nEvery one of these changes I have made, each in a separate rebuild, has produced a marked improvement, and I wonder if it is now limited by the Heil.\r\nTo the point. Does any one have experience with this unit, and how do you guys regard it? Is it fundamentally flawed? It is used in the ESS Connoisseur 450, reviews of which can be googled, and all of which are good.\r\nI would be very grateful for any pointers, opinions and help with this; they are used as my (only) main monitors in my studio.\r\nMany Thanks for any help. Pharos.