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About RTally

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  1. I had a pair of Advents that had dark colored open-celled foam inside. That foam is speaker fill and does not degrade over time. It is very similar to the foam often found in seat cushions. It is safe. Put the foam back in the speakers in the same relative position that you found it.
  2. RTally

    Baby II crossover

    Generally, I find the best source of crossover information is what is installed in the speaker. Manufacturers often make changes during production. And not all the changes are documented. Sometimes the part changes are due to component availability. Sometimes it is a design change. I suggest waiting until you have the speakers in-hand and then inspecting them to see what is installed.
  3. RTally

    CB-10 crossovers

    The tweeter is wired out of phase to the woofer. Why? The designer determined that the speaker sounded better at the crossover point by shifting the tweeter phase. It may be that the the phase angle between the two drivers was sufficient at the crossover point that wiring the tweeter out of phase made for a flatter response at the crossover. The 7.5 ohm resistor forms a portion of a voltage divider circuit with the other resistors. With the switch in the illustrated "Decrease" position, the voltage divider is a 3 ohm equivalent resistance and a 7.5 ohm resistance. Moving the switch to Flat or Increase reduces the 3 ohm equivalent resistance and increases the resistance of the lower portion of the voltage divider, resulting in a higher voltage applied to the tweeter and less attenuation.
  4. Please do not ruin any speakers by trying that unless you plan on testing some sacrificial speakers over time. it is hairbrained ideas like this that caused people to think latex, Permatex, white glue, and other crap was a good idea for surrounds. The proper butyl compound is readily available and has been proven to not damage speakers.
  5. With current camera technology, large-format scanners are not necessarily needed for scanning drawings. I am finding that using a camera to capture documents is more convenient and typically as good a quality as using a scanner. Line drawings, in particular, do not require high resolution scanning. A good option to scan large drawings is to mount them on a wall and position the camera on a tripod with the lens centered on the drawing. If a smartphone camera is used, depth of field can be increased by using very bright lighting. It is important to ensure that the drawing is flat. I am used to large-format drawings (D to F sized) being stored flat, not folded.
  6. There are two parameters of importance for capacitors. The obvious one is capacitance value. The other is equivalent series resistance (ESR). A change in capacitance value will impact the crossover frequency. For a first order filter, it takes a large capacitance value change to create an audible null or peak in the frequency response. A change in ESR will attenuate the tweeter volume for a high pass filter. Generally, changes in ESR will be more audible than capacitance value changes. Too high of an ESR causes the speaker to sound muffled, as if a blanket is thrown over the speaker. If ESR is to be tested, the test meter must use a frequency in the audio range for the test to be meaningful. To answer your question, it is possible to have a cap that test within spec for capacitance value but out of spec for ESR. Such a cap needs to be replaced. To test a cap, it needs to be removed from the circuit first. At that point, why waste time testing except for intellectual curiosity. Once the cap is removed from the circuit, you might just as well put in a new one. If you want to test, a better test is done with a real time analyzer (RTA) to check the FR of the speaker. I play noise and use a phone app to check the FR of my speakers. For simple checks, the phone app is fine, but a proper RTA and mic would be best. Using a phone or RTA is a simple, objective way to determine if there are any unusual nulls or peaks or attenuation. It also allows for easy verification of operation of any switches or pots in the crossover circuit.
  7. I have a pair of Legacy II speakers that I refoamed. I understand your love for them. The first thing to do is to pull the grills off and check the surrounds on the woofers. The surrounds are foam and have a limited life. If you have had them for a couple years, it may be time to refoam them. Look for the foam being cracked or brittle. It should be soft and supple with no breaks. Post pictures - just make sure that they are sized to be 100k or smaller.
  8. Testing the tweeters is easy if you have an ohmmeter. Remove the tweeter, disconnect at least one wire from the tweeter terminals, and measure VC resistance with an ohmmeter. If you put in 8 ohm tweeters, they should measure about 5 to 7 ohms resistance. If you don't have a meter, get down to Harbor Freight and buy a cheap $2.99 meter. Those are fine for troubleshooting and quick checks. While you are removing drivers, pull the woofer and inspect the crossover components. Look for any discoloration of the resistors. Measure the resistors to see if they are still resisting properly. Hopefully, you just burned up a resistor. You don't say if you have the original (OLA) or the new (NLA) advents. Check out the crossover info at http://baselaudiolab.com/ADVENT_LA_XO.html Post pictures. The pics could be a lesson for others.
  9. RTally

    AR 58s

    Not series, but parallel. When capacitors are wired in parallel, the capacitance values are added together. You can get 8 uF by wiring two 4 uF caps in parallel. uF is same as mfd (microfarad). The voltage rating does not matter as long as it is equal to or greater than the original voltage rating. It is easy to go down the rabbit hole when recapping speakers depending upon how much you want to spend. It is generally accepted to replace old electrolytic caps with poly caps. I prefer Audyn Q4. Others like Dayton caps. Those two choices are the lowest cost options for non-electrolytic caps. Many suggest using electrolytic caps for the larger sizes in order to keep costs down. Over the years, capacitor construction has changed, a lot. New poly caps will be a lot larger than old electrolytic caps. Physical size only matters when it comes to figuring out how to install the replacements. If room is limited, caps can be mounted separate from any circuit board, if there is one. A good source of low cost crossover caps is Parts Express, which is where I get mine.
  10. The best way to ensure that the surrounds are sealed properly is to test them mounted in the cabinet. Push the woofer cone in and hold for about 20 seconds. Longer is better. There needs to be enough time for the pressure in the cabinet to equalize with the ambient air. Quickly release the cone and measure the time it takes for the cone to return to resting position. Any time longer than about 1 second indicates a good seal. Longer is better, but rarely achievable beyond a few seconds. Less than 1/2 second, means you should check for air leaks. Before adding more dope to the surrounds, the cabinet integrity must be verified. All drivers need to be sealed to the baffle. The cabinet seams need to be solid and sealed. The rear terminal panel must be air-tight. And the woofer dust cap needs to be sealed. If the cone rebound is very quick, one technique is to listen for leaks as the cone is pushed in and released. Only apply more doping if you are certain that the cabinet is well sealed.
  11. I quick google search indicates that the Rogers LS3/6 are very good speakers. I would have snapped up those speakers. When I see a deal like the above, my first contact with the seller is to give him my phone number and tell him that I am ready to buy and can meet him wherever he wishes at any time, preferably now (considering drive time). My only questions are when and where. If I have any other questions, I wait until I see them. When good deals pop up, you have to react fast or expect to lose out.
  12. I have refoamed many speakers and have never had a problem using Aleene's glue between the foam and the metal basket. As noted above, ensure the basket surface is clean.
  13. Seems like everyone else has covered the rest, but I want to caution you about using wire wool (Steel wool in the United States). If the wire wool is magnetic, you must remove all the drivers from the baffle before using the wire wool. During use, wire wool leaves fines, which are very small metal pieces. The fines will be attracted to the magnets in the drivers. If the drivers are still installed, the fines will be attracted to the front of the drivers. You do not want this to happen. Also, many woodworkers do not like using wire wool because the fines also get caught in the wood grain if not careful. Instead of wire wool, I suggest using a solvent to remove the grime and old finish. Then use a fine grit sandpaper to touch up the surface. I like to use 180 or 220 wet-dry sandpaper with a sanding block. You can then use oil or other finish that you prefer.
  14. That is a loaded question. At the risk of starting a controversy over caps, . . . Electrolytic caps are inherently noisier than film caps, but it is questionable if it is audible. The way the electrolyte reacts inside the cap is the source of the noise, as compared to the solid material of other caps. Film caps will last longer than my lifetime. Electrolytic caps have a limited life, typically 15 to 20 years, maybe 25 for modern ones. Film caps cost more than electrolytics when looking at economical options. Electrically, electrolytic caps better match the original caps in the speaker if those caps were electrolytic. Film caps will have a lower equivalent series resistance (ESR), which will result in a slightly brighter sound. Many add a 1/2 ohm or so resister in series to accommodate the reduced ESR. For me, I use electrolytic caps when recapping inexpensive speakers that I do not plan on keeping. For the better speakers that I plan on keeping around, I use film caps all around, even in the woofer circuit. My brand of choice is Audyn Q4. If I ever get really expensive speakers (valued at over $1000), I will likely use better quality caps. I do not like spending more on caps than the speaker is worth. I also recap one speaker at a time and A/B test to ensure it is worth it. Usually it is.
  15. Generally, it is not worth the effort to measure caps except for personal gratification. Since you have to remove them from the crossover to test, you might just as well install new caps and be assured of a future, long service life for your speakers. When testing, you need to measure both capacitance value and effective series resistance (ESR). Many times a cap will be within spec for capacitance value but the ESR has increased as the electrolyte has dried over the years. The increased ESR contributes to attenuated mids and highs. As JKent mentioned above, those black caps with red ends are notorious for failing. They have a reputation for failing catastrophically, as in exploding. Regardless of how they test, I would immediately toss them and replace with film caps.
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