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.
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Or just look at the color rings. Plenty of websites where you can decode the colors. The values may have drifted over the years so what you measure may not be within tolerance of the nominal value. Also, if the quality of you solder joints is anything less than the factory, it could negate any advantage of a better resistor. 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. |
Thank you all for this. I do appreciate it. I'm new to this. I did have the connections to the actual speaker elements soldered and that made a nice improvement in the sound. Removed a kind of rizz or roughness I had not noticed until it was gone. These speakers have a wonderful top to bottom consistency or coherence I haven't heard before in a cone speaker. I have heard other speakers do certain things better but not overall. The bass quality is very accurate as well. Again, thanks for your input and if you have more data on this it would be welcome. This speaker is worth every minor improvement added to it. Jonathan |
Keep in mind that Dunlavy chose resistor values on a per-speaker basis, choosing slightly different values until the speaker measured just right. Therefore, you may not find a schematic with specific values and one person's set most likely has slightly different values than another set. Many of the sand resistors on the xover are glued one on top of another in parallel, so one would need to remove them to be able to read the values (they do not have color band indicators on them as Ge5556 suggests). Also, since many of them are connected in parallel, in-circuit measurements are not recommended. The best way to find the values would be to remove them and read the markings on the top of the package or measure them individually. I too faced this same dilemma with my pair of SC4a's and after much research and thought, decided not to monkey around with changing them out. If you do want to take the plunge, use 10W non-inductive resistors such as wire wound Mundorf's. Two tweeks that I made to the crossovers that made a nice improvement in sound quality was to replace the binding posts with Cardas CCGR-L type and coat the components with AVM (Anti Vibration Magic) available from AuDIYo. Finally, as an aside from your topic, placing the speakers on Star Sound Sistrum SP-101 stands makes a big difference in sound quality. That is what I did and love the stands (looks cool too). email me offline if you want to chat. |
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. |
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 |
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 |
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 |
Here is what I did to my SC IVAs that didn't work, from subtle to bad. 1. I put short cones under my SC IVA bases. It made almost no difference. If forced to decide, I'd leave them there but either way I don't hear a big or even small difference. I think the bass is slightly tighter with the feet. They are some generic cone and not high quality. As a note I have a very thick solid concrete floor with an indoor outdoor carpet over it. Basement studio. 2. Two Audiogon members said to remove the bases of the SC IVAs and it would make a noticeable improvement. I did this and the magic I had gained from my other improvements completely disappeared. This was not subtle. My system was worse by about 10%. I have no idea why but it was bad. I put the bases back on and voila. The great presence I had achieved was back. Without the basses the sound was recessed with loss of solidity and presence. Frankly this makes no sense to me why this would be so much worse, but it was. These are the only changes I made that either made little difference or were worse. Jonathan |
Dear All Who Helped me, As a final note I chickened out on any other changes to my SC IVAs after taking the bases off made such a negative change. My system sounds great since re-attaching the bases so I'll leave it at that. If anyone finds any other changes that really help I hope they will post it for our mutual benefit. But for now no more major changes for me. Thanks again. Jonathan |
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. |
Respectfully to Shadorne, 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? My experience with DAL and Duntech speakers suggests two conditions. The speakers are of such quality that listening outside the "sweet spot" can still be very pleasurable. But I will admit that to optimize critical listening, where you sit will be important. And this relates to vertical position of your ears as well as horizontal position. This is because of the D'Apolito array of drivers -- think of them as a stereo pair turned 90 degrees and it should be obvious why placing your ears at tweeter level is important. Back to Jonathan, for your DALs I would do everything that is practical for placement and room treatments before worrying about future tweaks to the speakers themselves. Just as with any quality speaker system, you should start with the environment where they are ask to perform. |
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. Assuming you meant an unshaded light bulb (360 degree radiation) compared to a spot light (believe flood lights come in a wide variety of radiation patterns) in your analogy, it seems to me the opposite would be true. From my reading on speaker placement, acoustics, and room treatments, it appears that a minimum of 10 msec delay is typically recommended for reflected sounds compared to direct sounds. This minimizes smearing and improves clarity. Now the narrower the dispersion (more focused, like a spot light) from a given speaker, the less the intensity of the sound waves reflecting off the sidewalls. Conversely, the wider the dispersion pattern, the greater the intensity of the reflected sound waves and the more important placement and/or treatment would become to satisfy the 10 msec or greater delay objective. Both DAL and Duntech designs are fairly wide dispersion which is why sidewall reflections are critical to optimum set up. |
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. |
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! |
John Dunlavy's placement recommendations: Yes, John typically suggested long wall placement. This was (in part) to maximize speaker placement from the sidewalls. He recommended greater distances from sidewall to the center axis of drivers than from the front wall (long wall) to the front baffle board. Also he called for toe-in aimed just behind the listener's head. However he did not recommend anything near 120 degree separation between speakers. He specified 45-70 degrees with 60 being the optimum. In fact he preferred an equilateral triangle placement of speakers relative to the primary listening seat. But since he also specified a 3-3.5 meter listening distance (for full convergence of drivers on his floorstanding designs), this results in greater physical separation of the two channels than some designers recommend. My listening experiences with both DAL and Duntech speakers bears out the benefits of avoiding close sidewall placement. And . . . I don't feel cross threaded on this at all. I just wanted to understand your perceptions on dispersion. |
Dear All, Again thank you. Unfortunately or maybe fortunately my speakers are very limited where they can go. This is because they are used in my studio to make digital masters and produce my jazz radio show. In fact I never sit down and there is no chair to sit down. I work standing up at a digital workstation which has a stand up desk. My speakers are on the long wall about 8 feet apart and about 2 feet from the left side wall and about 4 feet from the right side wall (this imbalance is not optimum I am sure). And about 4-5 feet from the back wall. Yet for some reason this sloppy placement (by necessity) sounds wonderful. The speakers are world class sounding. I listen anywhere from 12 to 25 feet away depending on what I am doing in the studio. At 25 feet they sound slightly better. I can hear the smallest changes in sound. I am sure others in this forum have a much better set up as this is really rinky dinky (except for my floor which is very very thick concrete with indoor/outdoor carpet over it. But this placement works for whatever reason and the sound is quite good. And getting better as I make minor upgrades such as the brass screws, cardboard on top, etc., as described earlier in this forum. Any suggestions I'll try and implement but I have limited maneuvering room. Jonathan |
Dear All Dunlavy SC IVa Owners, Has anyone come up with other improvements to the SC IVa since our last thread of Sept 2008? I have since added Walker Feet under the bases of the speakers to good result. And I have added two Sunfire MK IV subwoofers but set at a very very low frequency (25Hz) and at a very low volume so they just add a touch of low base. This opened up the midrange nicely. My normal experience with subs has not been good, so this surprised me. No other changes since Sept 2008. Hope to hear from all of you again. |