Dunlavy SC IVA X-over resistor values

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.

Again I want to thank all of your for your very helpful and intelligent comments and observations. I hope my questions and quest here will help you all in turn. My concern now is I note two of you did not elect to replace the resistors and I guarantee you that those who declined to do this are more capable of such a task than I will ever be. Without direct knowledge, and I stress that, I do not believe John Dunlavy had the time to hand pick his resistors or tweak them for each speaker other than to buy them in lots and stick them in the speaker. I am convinced that fine quality resistors (and capacitors) would make a major upgrade. I cannot back up this statement except it has been my experience in the past with other components (which my engineer soldered in for me). I know I recently made two minor adjustments with cardboard on top of the speakers and brass screws on the tweeters and I heard a noticeable improvement worth the $5.00 for the thick cardboard and the $2.50 for the eight screws. I also had the speaker elements soldered bypassing the cheap clip ons that are used to connect to each speaker element. That made a very nice improvement. I will next take off the Dunlavy basses and put cheap points under them and then in a week or so add the Star System points. Then once I have that settled and confirmed as better I'll somehow confront those xovers. From all of this I will also do a summary of what actions I took that improve a Dunlavy SC IVa and for how much money. I will include resistor values and whatever detail I can to help others. That way we all will have a complete record of this. I believe this speaker is worth the effort and whatever pain. I hope you all will keep giving me input and suggestions as you think of possible upgrades. I really want to hear more from you all. Like tonight. Jonathan

Shadorne good read,

When I went external with my Dunalavy SC4's crossovers I hard mounted all the components on 2024 1/4 inch aluminum plate. This material has a high percentage of copper content and is vibrationaly reactive in a good way. All resistors were Vishay metal film and were built 10 up as a bridge type so as these low powered super sounding resistors would handle the wattage. Of all the components swapped out these made for the single largest increase in fidelity. The cabinets themselves were sealed internally with Cascade Audio paste, a latex based product that is drawn into and seals the wood pores. This is not a damping material for it drys like concrete. This material made a huge difference in soundstage size shape and detail.. All fasteners were of brass. The finished out crossovers weighed seventy pounds each with their 10 runs each of driver cable. The primo finishing touch was the improvement made when these external crossovers were placed upon Sistrum SP101's. Resonance to ground control! Tom

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.