Dunlavy SC IVA X-over resistor values

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.

Shadorne, The second speaker system I ever owned was Tympani 3a's tri-amped. Very complex system to get my arms around. I was only 22 then and the imaging imbalances in my room at that time drove me nuts. The room was large and so were those panels all the complexity and variables were way ahead of my audio encylopedia at that point in time. Every system since then has been bi-amped, supplemented with subs and electronic crossovers including the Dunlavys. This of course brings about other issues namely phase shift at the crossover point. I can now measure and compensate for these phase induced suckouts in frequency. Tom

Jonathan, first off, I think you underestimate Dunlavy's build quality. Do you think John was hand building every speaker? No, but he had a staff to work on his assembly section. Every driver was measured (with a file kept on your speakers so long as they remained in business -- to allow for a matched replacement if needed) and crossovers were measured and constructed with care to maintain the time/phase design John Dunlavy considered so essential.

However, there are a number of tweaks performed on Duntech and DAL speakers. Here is a link that identifies several:

http://forum.audiogon.com/cgi-bin/frr.pl?rspkr&1028246710&read&3&4&

But you really have my curiosity, what is your cardboard on top of your speakers mod?

Thank you all for your continued input. My unsubstantiated premise regarding some of the parts in the SC IVAs is that Dunlavy did not have the time to hand match each component in each speaker. Nor did he want to jack the price of the speaker way up with the absolute best parts. Whatever, some of the parts can be improved judiciously. On the other hand, Dunlavy hit the jackpot with this speaker as something about it is so right and so coherent. The bass quality is as good as I've ever heard from a cone speaker. So messing with it is a careful process. Here is what I have found so far that improved the speaker all based on input from Audiogon members (since I had no clue about these matters--I can just hear the smallest changes in my system). 1. I put cardboard on top of the speakers. I bought thick cardboard flat boxes at UPS store for 5.00. I cut it up so one flat piece about four feet long was used for each speaker. I then folded the cardboard so it sat on the speaker kind of like those small picture frames do with the picture leaning back and a support behind it leaning on the table it is sitting on. In this case it sits on the speaker slanted back away from the front. Hope this is clear. The theory from Tom is that it helps equalize the distance that each woofer is from a surface, the bottom woofer being closer to the floor than the upper woofer. Did it work. Yes. This is a minor but worthwhile upgrade which makes the images a bit more stable and present. I took them off and on to check this. If I keep these there I'll cover them with speaker cloth so they look a bit more coordinated. Right now they are ugly as sin. 2. I replaced the tweeter and midrange screws with brass. This made the highs less tizzy and more solid. 3. I had the speaker elements themselves soldered instead of using the cheap push-on connection tabs that exist on each speaker element. That really improved the quality, smoother. 4. I installed a direct electrical line from my elect service box right to the wall that my amp and pre-amp plug in. I had VH Audio tell me what to get. I put in new outlets (Oyaide receptacles and #10 wire.) Major change for the better with solid images, less noise, etc. By the time all of these improvements were done my speakers sounded about 10-15% better. A major improvement for speakers that were already wonderful. Those are the improvements. Next I'll post what didn't work and in fact ruined my sound temporarily. And ask for data from those who have made the resistor change to the SC IVAs. I cannot imagine it not making a major difference. Jonathan