The TB wide band drivers ,especially the 4", offer a very good bang for the buck.Their shortcomings are a low efficency and generally higher Qts. The Qts although may not be a drawback in the correct enclosure. IMHO the 4" drivers have a too high Qts for use in a BLH but would work well in a FLH. I have build just one set in an old fashioned (pre Martin) TQWT for a friend and the results were more than acceptable. ron