First mark them carefully - so you know exactly where they are mounted. Then take them out (solder gun and sucker tool) and simply measure them with a multimeter. You may need to buy several resistors to find something that is very close. Normally resistors have +/- tolerances. Good luck - and make sure you pay attention to the power ratings too.
Showing 9 responses by shadorne
Shadorne, why can't you just measure them in place at the shoulders without removing them? I didn't think it would throw it off that much. You can probably do that on the woofer. However, generally the resistor(s) on the tweeter may be in parallel with the voice coil or something else that conducts at DC. You can remove one end and measure it that way.... Your point about reading off the values is correct but most manufacturers will select parts to improve the precision of the crossover....certainly Dunlavy would have done probably done this and you want to stick as close as possible to the orgininal. FWIW - I'd not bother with the resistors or inductors (air core most likely) on DL's - if anything it is only the caps that might deteriorate after 10 to 20 years....unless there is a well known problem with one of his designs? |
Here is some recent research as why you might worry about capacitors rather than resistors (especially large caps and ones that carry higher voltages - so this affects passive speaker crossovers as well as tube coupling caps most) See this ClarityCap Research. Note that the measured resonance (from capacitor changing shape under load) is extremely small but it does cause IMD distortion, which tends to be much more audible than other forms. |
Vishay metal film Impressive crossover WOW. Of course these type resistors would be the top choice in amplifiers and low level signal circuitry. However, non-inductive ceramic wirewound resistors are just as good and you don't need to bridge them as they come in useful power ratings (unlike the metal films which are only rated at low power) and noise levels are well below 100 db compared to the signal for both. See this info Vishay Audio Noise Reduction Actually, considering your impressive efforts, you might take a look at active crossovers - technically, this is by far the best way to improve accuracy/reduce noise because you can do the filtering at "signal levels" rather than high power levels. Once the circuit is warmed up and "tuned" you are done...furthermore your crossover stays precisely as it was designed under all conditions (loud or soft music) - no crossover drift as voice coils heat up/coll down with each loud and soft passage - causing unrelated IMD distortion to harmonics over the crossover region! Say for example, something like the HR-X Crossover used in studios. |
if DALs have a narrow dispersion then why is distance and angle from the sidewalls so critical, as well as the reflectivity of these walls? Precisely because they have narrow dispersion! Narrow dispersion speakers, when listening far-field, are typically very finicky about position. Think about an ordinary light bulb versus a flood light - what you see is a combination of direct and reflected light. It is the same with hearing. To continue the analogy, the lighting in the room will be most even with the omnidirectional light bulb (more reflected light). The light bulb is clearly less sensitive to location/direction. The flood light will be much more sensitive to placement/direction...only with careful positioning can one get the desired reflected light to evenly illuminate the sweetspot. It is the same with speakers - wide dispersion makes placement very easy. |
Shadorne, I've read your response a couple of times and it does not make sense to me. What you hear is a combination of direct and reverberant energy. The 10 msec rule is for precise imaging - getting a fix on where a sound came from, however, your brain still adds or hears the reverberant energy that occurs after 10 msec (it tends to be ignored however in terms of direction provided the brain figures it is part of the sound). You need to read up on Haas effect - bascially anything up to 30 or as much as 40 msecs gets added to the sound by your brain ( you hear it - which is why a certain amount of reflected sound/echo/reverb enhaces the audibility of music). Anything that occurs much later than 40 msecs is often regarded as a distinct or different sound by the brain - this is why large highly reflective gymnasiums make for terrible sound. Bob Katz has written some stuff on this, as have many others. Don't ask me why our brains work this way but they do. |
DAL's have narrow dispersion. You need to pay precise attention to exactly where you position your head when listening and making A/B comparisons. A few inches may change what you hear when listening critically. Typically it is recommended to place them far apart and toed in - this means if you lean forward then the sound may change considerably too. |
My comment was that in a "far-field" a narrow dispersion design type of design can be tricky with placement. I believe Dunlavy recommended placing some of his designs on the long wall, far apart at 120 degrees, and toed in - this is closer to "headphones" than a more conventional 60 degree equilateral triangle speaker setup (you get far more direct sound and less reverberant sound with Dunlavy's suggested setup). However I must add that I don't have at home experience playing with DAL's and your extensive experience seems to contradict my understanding...perhaps other DAL owners can chime in... I hope we are not getting cross threaded on this ;-) I readily admit that DAL's are some of the most highly regarded speakers of all time! |