BEC
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Posts posted by BEC
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10 hours ago, Schu said:
what values are needed Bob?
Those values are in the schematic posted earlier.
Bob Crites
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Here is a picture of a before and after rebuild on that type of Heresy II crossover. Hardest part on this version is getting the wires unsoldered and unwrapped from the input terminal posts. On this one they chose to have the input terminals actually penetrate through the circuit board and connect on top with two stiff wires. Sort of a pain to get those loose so you can get the board off to get to the back side of it.
Bob Crites
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Do a Google search on "2004 Ford F150 Vibration". I have one I bought new. Never did get that all figured out. Ford likes to say just inherent to the vehicle.
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When you want accurate low-ohm measurements, the leads are super important. You may want to know DCR of an inductor that may be on the order of 0.1 ohms. It is very easy to have more resistance than that in the test leads or even in the contact resistance of measurement probes. So, no matter how good the meter is, go for quality leads preferable with gold at both ends contact surfaces. When the meter is set up for them, Kelvin leads just take lead uncertainty out of consideration.
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I use the B&K 885 meter. Have had that for many years and it was at that time the only one I could find that did all I wanted it to do. I think there may be other choices now that are less expensive. The B&K 885 is around $600.00 but sometimes discounted.
http://www.techedu.com/BK/LCR-Meters/BK-885-Type-Hand-Held/
Then you still need Kelvin clip leads if you are really going to take any meaningful low-ohms or ESR measurements.
http://www.techedu.com/BK/Probes/Leads/Cables/BK-TL08C/?v=69944&r=1
B&K also has some less expensive models like the 879 which retails at $299 that may be good also. Would need the optional Kelvin leads for that one also.
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1 hour ago, rockhound said:
watching this closely as this was a mod I have considered doing. Bob I'm down the road in Murfreesboro if you ever want to experiment with a set of CF4's.
I don't really want to do that with a borrowed pair. If a rough pair comes along with all drivers working, I would like to buy them and work that all out.
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Sorry for your loss. Thanks for letting us know.
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Well, any change to the HF driver would require first testing of the raw driver on the CF horn to see how it performs. The current crossover first boosts the HF output by 4db by using an autotransformer run backward. Normally we see the autotransformer used to attenuate output, but in this case it is used to boost output. That is to raise the output enough to allow the EQ circuits to decrease output at certain frequencies to get a more linear acoustic response. It would really surprise me if any other driver on that horn needed exactly that same treatment to make it linear. So, I think logically, a new crossover design would be needed to address using a replacement driver.
At this point, all of this is just a thought exercise for me since I do not have a CF-3 or CF-4 to test to see what actually happens with a replacement driver. Perhaps the Chief may come along at some point to clear this up a bit for all of us.
Bob Crites
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Something to be considered. The crossovers for the CF-3 and CF-4 have EQ circuits in them to correct the response of the original driver that Klipsch used in these speakers. It is unlikely that any other driver you may find to replace the original driver with would need EQ in exactly the same places the original driver did.
Bob Crites
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If you were not measuring right at the woofer, the extra resistance could have been in the little terminal strip. Might be a bit of corrosion on the screw connections.
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57 minutes ago, Mr._Music_Fan said:
Dear Comrades!
Sorry to have been MIA for a while, I was in a pretty nasty auto accident and got T'boned. Thus, I am finally being able to get around to resume my work on my LSi's. I will be posting new pics after dinner. Today was very productive, I was able to get both of the K43's installed back into the doghouse. I tested the K43 to ensure I connected the leads correctly and one of the woofers was coming in at 6ohms, and the other one is 3.8 ohms. For clarity purposes, I am measuring the woofers directly at the connection spot in the top box, not using the crossovers. Shouldn't both be about 4 ohms? Should I be worried/concerned about the woofer measuring at 6 ohms? If so, what can I do to fix this?
Thanks in advance all.
The one measuring about 3.8 is right. The other one may have been reconed using the wrong (8 ohm) voice coil. That happens pretty often.
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4 minutes ago, billybob said:
Thanks very much Bob for your intuition
Not intuition, just experience. I have talked people through that particular problem perhaps 50 times over the years.
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There is also a white dot on the diaphragm that indicates positive. Having the mid signal shorted would also effect the tweeter, but probably not stop it from working completely. You could also have a blown diaphragm in the tweeter. Something that happens all the time.
Bob Crites
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Check to make sure you reconnected the wiring correctly to the midrange driver. There are two terminals on each side of the driver. One of the wires should go on one of the pair of terminals on each side of the driver. You could plug the wires both in to a pair of terminals on one side of the driver. If that is the case, you would be shorting out the midrange signal.
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1 hour ago, Deang said:
I know how an L-pad works, I even know how a T-pad works!
Did you read the three pages I posted?
If you want to bring down the driver a dB or two, use the autoformer and adjust the primary capacitor value to keep the crossover point from shifting.
Remember that I showed you a crossover that PWK used L-pads on. They were discrete resistor L-pads at least. I don't think he wanted to use them, but had to use them to get the speaker to work right. I wonder if Roy is familiar with that crossover.
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Chief,
I use a spectrum analyzer (Stanford Research Model SR1+) that sweeps 0 to 25K at 1 volt into the crossover input. All outputs are terminated into the expected impedance with resistors and I run a trace of woofer, squawker and tweeter all plotted on top of each other. I can see the electrical crossover frequencies and voltage output of each section. I do that for every crossover I build or rebuild.
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Mark,
I consider very low ESR and very consistently low ESR cap after cap as a mark of quality in caps. With that as a standard, the only ones I have really liked were the GE motor run caps I started out with and the Sonicaps I used when the GEs were no longer produced. Another reason is the to the best of my knowledge Sonicraft is the only company that produces capacitors in all the values we need for Klipsch crossovers.
I could list many caps that would duplicate the original signature if you go through them and do a bunch of testing of the parallel combinations you have to use to get the values. I personally just eliminate most of them because they are not produced in the right values or they specify a 10 percent tolerance. I can't imagine how loose their manufacturing process must be if they can't specify a better than 10 percent tolerance.
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28 minutes ago, mark1101 said:
What reference should be used? If the networks are from 1979 will the current FR be a reliable reference?
I guess this has been the problem all along. There are no recommended replacement parts for speakers that old (unless I don't know where to look). Then everyone uses all these different capacitors.
I just recapped my friend's 1979 lascalas (AAs) with Dayton metalized polys (1%). They were cheap and have a decent reputation. Thought they came back to life based on what we heard as a sound improvement........but we will probably never really know how they compare to factory sound from 1979.
Let me tell you how I did this. I was rebuilding lots of AA crossovers around 10 to 12 years ago. I was also testing the old caps to see how they had changed. Most of them had a pretty high ESR, but just occasionally, I would find one that read very good on ESR and capacitance. I mean an ESR of less than 0.1 ohms. Pretty soon I had enough of those old caps that read good to use them together in a new AA crossover. I ran curves for that crossover on the spectrum analyzer. Then compared that to curves I got with the new caps I was using. Almost a perfect match. Just to see the difference I did that comparison again with some old caps that all tested about 0.5 ohms ESR. Could see some difference there.
So, I think, as long as ESR is low enough, doesn't make any difference if the dielectric is paper, mica or whisky bottles. That last sentence paraphrases a statement of PWK in a letter written in 1984.
Bob Crites
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Sorry to hear about your loss. Prayers for you and the family.
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Just got a bunch of the parts in the picture. This is the complete magnet assembly for the K-77F including diaphragm. So, you would just remove the horn from your K-77 or K-77M and put that horn on this magnet assembly. Works with the same screws you have in the K-77M, but for the round magnet K-77, you would need 4 8-32 1 1/2 inch screws.
Contact me by email if interested
Bob Crites
bobcrites@mac.com
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Are these not the right zeners? I copied this link from page 1
http://www.parts-express.com/12v-5w-zener-diode-do-15-case--1n5349
Sorry but no. Thanks to your post, I did some research and found that the Zener diodes need to be 10 watt (5.1v). Furthermore, there are two Zener diodes per crossover. I have updated the original post to reflect the cost of these products, but suffice to say they are indeed very expensive. The total cost is over $120 per pair of networks before shipping.
Klipsch community I need your help. I have a question for you. What tweeter protection can you install if you don't have a Zener pair on the AL you own? What about the protection on the AL-3 or on the KP-201?
I buy those in large quantity so could provide them at a significantly lower price than you show.
Bob Crites
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Probably does not make any difference either way, but I always leave it on. Do not touch the shiny dome. Very easy to damage it. Many have damaged the dome trying to take the yellow paper off.
Bob Crites
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Bob... I wonder if grill material has a rating to describe how transparent it is sonically?
I really don't know the answer to that. I have been told that Klipsch tests the fabric they intend to use, but I do not know what the testing standards are.
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Hmm wonder how transparent it is with the sound. Does it stretch or at least give a little?
The stuff I posted above is actually Klipsch approved. I have not seen them actually use it though. Yes it will stretch some.
Help with crossover rebuild
in Technical/Restorations
Posted
That would work if any of the crossover wires were left above the board. On all but one of the caps, you cannot even see the wires. The wires have been pulled all the way through with nothing left of the wire visible on top of the board.
Bob Crites