RTally
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Posts posted by RTally
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6 hours ago, DonT said:
Because when I am done testing it you will be able to buy the ingredients and have enough on hand to do 100 speakers for slightly more than Roy charges for one.
Roy's goo is not expensive. Most of the cost is for packaging and shipping. And as JKent points out, it is a pittance considering the other costs and labor involved in restoring great vintage speakers.
Also, without documented test results over time, I would not trust anything other than Roy's goo. For your goop to be accepted by those of us that know about Roy's goo, you have a lot of hurdles to overcome.
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For $250 a pair, they should be in pristine condition, freshly refoamed and recapped, and the veneered, beveled front, not the utility cabinet. I paid $50 for my OLA that needed to be restored. I've seen others for sale between $100 to $200, depending upon condition. Other places to check are Craig's List and Facebook Marketplace.
As for what to look for, if you audition, do all the drivers work, or, if no audition, does the woofer move freely and the drivers appear undamaged. Are the speakers recapped and have they been properly refoamed? For a lower, more reasonable price, I would prefer to recap and refoam myself because some cannot do a good job of it.
If they have been recapped, I ask questions and ask if they have the original caps (I save the old ones when I recap). The idea is to determine if they knew what they were doing and did it correctly. An audition may provide evidence of a successful recap or a need to recap.
If they have been refoamed, check that the foam was properly installed: for the original masonite woofer the outer edge of the foam is under the masonite (on the bottom side) and the inner edge is on top of the cone. For the replacement metal frame, outer edge is on the metal frame and inner edge under the cone.
I like my OLA, but I have many others that are their equal or outperform them, such Advent Legacy II, KLH 6, Genesis II, etc. My OLA is stacked with my Legacy II in my garage. They do fine filling the garage, the driveway, and the street.
Fortunately, I don't have close neighbors.
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Location information would be helpful.
Also, please list your asking price when you decide to sell.
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23 hours ago, JKent said:
I didn't use any black scrim, just the linen. I sanded the faces of the Masonite to get rid of the bumps from the staples then spray painted them black.
Then I use Aleene's Tacky glue. Cut the cloth about 1" oversize all around, then do one edge. I smear the glue with my fingers and press the cloth into it. It takes time, working the glue into the material and continuing until the glue starts to set up. Then I do the opposite end, pulling the cloth as tight as I can get it and following the same procedure. Then each side. It's time consuming but I've has good success. Then it dries overnight, then I spray the linen with water and dry with a hair dryer. The result is nice and tight. This is the method I've used with little KLH Model Eight grilles but it works for full-size ones too.
I use a similar technique except I glue one side and then clamp it while I work on the opposite side. I clamp the opposite side when I get it glued.
I have some aluminum bars (about 1/8" x 1/2" x 20") that I place against the glued section. I use paper spring clips as clamps. It is compact and works well for me. I can usually get the cloth tight enough using this method without resorting to spritzing. The Aileene's glue has enough working time to let me stretch the fabric to align the fibers with the edge.
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On 11/12/2020 at 8:04 PM, brianw said:
After all the xover rebuilds and other refurbishing both of my AR 9 sets are spectacular.
Not being someone who understands xover design, what roll does the UMR 6 ohm 22watt capacitor perform ? Is it to lower the output of the UMR ?
Thanks in advance.
Brian
Schematic fromAR is doing some fancy crossover work with the upper midrange. The 40 uF cap, 6 ohm resistor, and the 1.37 mh inductor are in parallel with the VC. A capacitor and resistor alone would form a Zobel network, which is used to smooth the impedance curve for that driver. The resistor in the Zobel network defines the upper limit for the impedance over the frequency range in which the capacitor presents minimal impedance.
See https://speakermakersjourney.blogspot.com/2016/12/crossover-basics-zobel_8.htmlGenerally, a driver will be attenuated by a Zobel network depending upon frequency. At the lower frequencies where the impedance of the cap is high, there will be little attenuation. As the frequency increases to where the capacitor's impedance becomes low, the resistor will decrease the power delivered to the driver based on the relative impedance, considering that the driver's impedance varies based on frequency.
With the traditional Zobel network, the frequency above the point where the capacitor has a very low impedance defines the lower end of the frequency range where the impedance correction is applied. If a Zobel network has an inductor instead of a capacitor, the frequency below the point where the inductor has a very low impedance defines the upper end of the frequency range where the impedance correction is applied.
But the AR crossover has an inductor in series with the cap and resistor. Not being familiar with the specific circuit in the AR, I would guess that the cap, resistor, inductor are used to shape the impedance curve in a specific manner over both low and high frequency ranges. I would be interested to see the curves XSim generates for SPL and impedance (assuming you have the response measurements for the drivers).
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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.
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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.
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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.
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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.
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On 5/24/2020 at 10:49 PM, tysontom said:
As for the "AR Archives." There are around 15 5-drawer, legal-size, filing cabinets full of data, many millions of pieces of paper, I suspect, and this doesn't include everything that was originally in these files. There are also thousands of large blue-line drawings and prints that can not be easily scanned unless a large-page scanner is used.
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.
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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.
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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.
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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.
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1 hour ago, dna said:
I have a pair of 58s speakers, one tweeter is dead and when the tweeter from the other speaker is connected to the first there is no sound. I was told this could be a capacitor, or I'm thinking one of those mysterious coils in the cross over. The capacitors are axial electrolytic. They have the values as follows:
All are 50V bi-polar, all are mfd.
4,8,24,40,100
I don't know if it's true but I was told that when running capacitors in series the value of each increases the capacitance factor by it's rating. For example 3 mfd wired in series with another 3mfd gives you 6mfd. I'm assuming that so long as the voltage is the same for each capacitor that factor doesn't change. If this is true I could put a few together to get the proper capacitance yes?
Maybe some one here knows where I can get the correct capacitors, all the ones I find on the internet are not the same size physically (does that make a difference?) but as I just need 2 of each some sellers on E-bay offer one of the ones cited but you got to buy a whole of them. I have tried Amazon, E-bay and did a generalsearch in Google too. Of course I get hits for everything but the thing I asked for....
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.
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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.
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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.
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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.
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20 hours ago, powerglide said:
I'm thinking not to mess with them too much, definitely fix
- Wire wool the veneer and re oil
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.
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On 12/1/2019 at 9:30 PM, DavidR said:
Why film caps?
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.
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On 11/29/2019 at 7:09 PM, wsill said:
Kent, ar_pro;
Thanks for the information.
I'm going to measure those caps tonight. I have a fluke multi-meter with capacitance measurement.
I'll let everyone know hoe the measured.
Bill
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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On 11/15/2019 at 12:08 AM, Jim Pearce said:
My main concern is the potential for damaging hardware.
Incidentally I am told that these particular tweeters go quite low.
I don't know what anything else you said means.
Ohm, I don't even know Um's Law.
Seriously, bro I don't know how to solder.
Seriously, if what I wrote above does not mean anything to you, I suggest you replace the tweeter with an exact replacement. It is not enough that that a tweeter physically fits into the hole in the baffle. The replacement tweeter must match the original tweeter electrically. Indiscriminately replacing drivers in speakers will most likely result in less than desirable results.
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The back of my KLH Six is labeled 8 ohms. I assume that means the tweeter has nominal rating of 8 ohms.
If you replace an 8 ohm tweeter with a 4 ohm tweeter the crossover frequency will double for a first order filter such as used in the Six. If you do not change the cap values, you will end up with a hole in the frequency response between the woofer crossover frequency and the new tweeter crossover frequency. That is, the woofer will roll off at its original 1500 Hz crossover frequency and the tweeter will pick up at 3000 Hz, twice the woofer's crossover frequency.
When replacing drivers, if an original, OEM driver is not used, the replacement driver should match the original TS parameters as closely as possible. If you do not want to rework the crossover, you need to at least match the driver impedance at the crossover frequency.
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On 11/9/2019 at 3:34 PM, becker158 said:
Could someone tell me what that wire is called?
The thicker conductor is the tinsel and connects the woofer terminal to the rivet that is supposed to be in the cone. Tinsel is very flexible and is typically a braided conductor with many very thin strands. The thin wire from the rivet extends to the voice coil (VC) and is the lead from the VC. The VC lead should be attached to the cone between the VC and the rivet (that is the purpose of the thin black line of stuff on the backside of the cone).
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On 10/19/2019 at 11:44 PM, Soundgarden said:
This is fascinating. Just bought some KLHs and am reading through all these threads for the first time.
Sounds like Roy’s treatment is a proven success. I plan to get some. But I also wonder about certain types of automotive grease. They stay grease forever (I.e. don’t harden) and can be applied lightly and without dripping or getting all over everything. Could such products potentially work as well?
I don't understand the resistance to using the proven doping compound made by RoyC. It is not expensive. It works very well. And it is readily available.
Using grease to seal a surround sounds like a bad idea to me. Grease, even thick viscous grease, will not stay on the surrounds when the woofers are played loudly. The rapid, back and forth movement of the cone edge will through the grease off the surround. I cannot imagine the mess that grease would make, both inside and outside the cabinet. And if anyone ever wanted to seal the surrounds correctly, that grease would not be fun to remove.
Either use the correct stuff or leave them as they are. If you do not want to improve them, leave them be.
Fortunately, I don't have close neighbors.
KLH 6 Need a Durable Material for Speaker Grills
in KLH
Posted
Masonite is not very strong. I've got some broken grills that failed the same way.
I am thinking some 1/4" plywood instead of the masonite. The plywood would be a lot stronger.