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Chris,Thank you for the link for the damping factor calculator. I always find it amuzing how much even short runs of thick cables decreases the damping factor. I currently run 10ft. of 10 ga Belden cable to each of my VMPS RM40s. Even though the amp I use has a rated damping factor of 750 (8 ohms) the actual damping factor seen by the VMPS bass drivers (3.5 ohm impedence) is ~140. Cheers,JohnP.S. On the Supermax OXO crossover Brian uses a very thin cable on the tweeters, and medium gauage cable on the midrange panels, and a thick cable going to the bass drivers.
Theory tells us that smaller wire has higher resistance, and CAN exhibit a bit of power loss in longer runs, especially with a low impedence speaker.But this small amount of power loss is easily overcome by simply increasing level.Something else HAS to be going on, and I think I may have found the answer.This link http://www.bcae1.com/dampfact.htm has a chart where one can easily the effect on DAMPING FACTOR wire resistance has.Tube amps have lower damping factors then solid state ones do, but Tube amps can sound mighty good.Some big Krells and Crowns have damping factors of over 1000, and we all KNOW how they sound, right ?
Quote from: ka7niq on 21 Oct 2006, 10:54 pmTheory tells us that smaller wire has higher resistance, and CAN exhibit a bit of power loss in longer runs, especially with a low impedence speaker.But this small amount of power loss is easily overcome by simply increasing level.Something else HAS to be going on, and I think I may have found the answer.This link http://www.bcae1.com/dampfact.htm has a chart where one can easily the effect on DAMPING FACTOR wire resistance has.Tube amps have lower damping factors then solid state ones do, but Tube amps can sound mighty good.Some big Krells and Crowns have damping factors of over 1000, and we all KNOW how they sound, right ?One often overlooked resistance is the resistance of the XO inductor placed between the speaker terminals and the woofer.A typical value would be 0.1-0.2 ohms, which is about equivalent to 50 ft of 14g speaker wire (based on"If you use 5ft of 14g speaker wire, the total resistance of the wire is .016 ohms." from http://www.bcae1.com/dampfact.htm).Also, increasing the resistance between woofer and amp can increase the amount of bass heard . This is quite unintuitive but here comes the explanation: the amp has less control on the woofer, the woofer generates more distorsions and thus more sound. The sound becomes warmer. I think that tube amps are warmer because of the lower woofer control.Not being a speaker designer, I am not completely sure about what I wrote above, so feel free to correct me if I am wrong.Bruno
Aircores above about 1.5mH have a DCR that is too high for use in a high quality LF crossover like the bass on the RM 40. We like the 14 gauge Erse SuperQ laminate coils for this reason. They are very large, don't saturate under 800W input, and have a DCR around .12 Ohms. In addition they don't have the large stray fields of the aircores. We use aircores on the trebles where the values are small.
If I remember correctly the xo point on those was around 155Hz or 166hz.B, can firm that up, but that is what sticks in my mind.Only after the FST was available did B, move xo's up to 200Hz-280Hz
Quote from: John Casler on 24 Oct 2006, 06:58 amIf I remember correctly the xo point on those was around 155Hz or 166hz.B, can firm that up, but that is what sticks in my mind.Only after the FST was available did B, move xo's up to 200Hz-280HzI would like to do a mid woofer update, and raise the crossover on mine.I would also like to explore crossing over to the spiral ribbon tweeters below 10K, IF possible ?
Quote from: ka7niq on 25 Oct 2006, 04:06 amQuote from: John Casler on 24 Oct 2006, 06:58 amIf I remember correctly the xo point on those was around 155Hz or 166hz.B, can firm that up, but that is what sticks in my mind.Only after the FST was available did B, move xo's up to 200Hz-280HzI would like to do a mid woofer update, and raise the crossover on mine.I would also like to explore crossing over to the spiral ribbon tweeters below 10K, IF possible ?Hi Chris,I think you should sell all the rest of your speakers, keep the current pair of RM40s and use one for a Center channel, and then get a new pair of RM40s with all the fixins'. Then you would have the most incredible frontal array one could ask for, for your HT, and the 2 channel would have all the xover points and woofage factors you crave. aa