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BEC

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Posts posted by BEC

  1. On 7/1/2020 at 1:29 PM, Srinath said:

    So Crites woofers (Believe they are eminence - American made - I like that) - as we all know $360 for a pair

    That is the eBay price.  Why would you want to  spend that much for the woofers?  Talk to me about them.

     

    While we are here, yes, Eminence makes my woofers for me.  They are made to the spec of the K-33 made before 1986.

    Bob Crites.

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  2. The AK-2 has 6db of attenuation which even the guys in the lab at Klipsch agree was a mistake and 2db too much.  They did that based on testing of the prototype of the K-55M which came in 2db higher in output than the K-55V.  Later when they tested production versions of the K-55M they found it was really the same output as the K-55V, so they corrected that back to only 4db in the AK-3.  Dean, I am pretty sure you heard that story the same time I did down at Hope.

    Bob Crites

  3. I first tried to do this back in 2011 right after working out the 2-way Cornscala Style D using the HF140 and LTH142.  Essentially just adding a tweeter to cover the top of the HF in the Style D.  Never made that combo really work to my satisfaction.  This current attempt will not likely be the HF140.  Not sure what it will be yet. I have a couple of different candidate drivers to use for the midrange, just need to find the time to do more testing.

    Bob Crites

  4. 16 hours ago, Dave A said:

    Yes I think it is the larger than K-77 tweeter so it should handle more. Don't know which exact tweeter it is and it seems records for the KP-250 are pretty spotty so some are not documented that I can find. My first time seeing this crossover for KP-250's and I thought I had seen them all by now.

     

      If I have time to do other things besides Boneheads class I have thought about swinging by to meet you if you are up to a visit.

    Yes, let me know when.

  5. I have seen a picture of the 2.5A but have never found a schematic or had my hands on the actual crossover.  I appears to use the same cap set as the 2.5B crossover except the 2.5uF caps were done using a 1.5uF and 1uF in parallel.  Also the zeners were on it but I don't know what part number zener was used.  Doesn't seem to be the same zener used on the Type AA crossover.

     

    Bob Crites

    2010-10-30_17-14-31_320.jpg

  6. Some of the crossover designs have a resistor in parallel with the poly switch which allows the tweeter to continue working at a much reduced level when the polyswitch opens.  Some like the KG-4 just have the polyswitch so the tweeter will go completely silent when the polyswitch opens. 

    Bob Crites

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  7. Happens pretty often to the woofer circuit since that one has no cap in series.  Normally not for the other two drivers since they both normally are protected by the DC blocking ability of a cap.  And usually the woofer voice coil opens before the fire can get going really good.  But if you leave the cap out of the autotransformer circuit you have no such "fuse" like a woofer voice coil to save you.

  8. I breadboard a similar circuit often when doing testing to enable easy changes in attenuation.  However, when I decide on the attenuation, I revert that circuit back to having the cap before the autotransformer.  I just would not feel safe leaving that large low resistance coil in there for the long term as a direct low resistance path to ground.  Thinking of course here of the chance that the amp could fail and put a high current DC supply across that autotransformer coil.  Now that can and does happen with the woofer circuit.  But in that case, generally the relatively small woofer voice coil opens petty quickly taking the path for current away.  The autotransformer with much larger wire will just continue to cook until something in the amp gives up.  Like I said, just can't get comfortable leaving that in the circuit long term and without me right there monitoring it.

     

    Bob Crites

     

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  9. There is much more to that than Dean said.  I could probably build a type A crossover from scratch quicker than I could turn an E-2 into a type A.  Lots of rewiring on the terminal strips (which are fragile by that age and likely to break) and also the inductor is wrong value and would have to be replaced.  And with what the guy is selling that pair of E-2 for, probably cheaper to buy a new pair of type A.

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  10. 21 hours ago, Maxwell_E said:

    On the Crites website he has these listed as padding the signal by 4db

    Normally autotransformers are used to attenuate or reduce the output of a driver.  In the case of the CF-4 the autotransformer is installed backward and it effectively boosts the output by 4db.

    Bob Crites

  11. 9 minutes ago, Schu said:

    This is a 70th, but I guess that would be 2017...

     

    41747349200_ec730ac368_k.jpg

     

    I guess that means I could use your 120's/lens and z brackets, correct Bob?

    Actually, I do not think you could.  Your corners of the cutout are rounded.  I think they would have to be squared off to have that horn fit.  They stopped squaring off the corners at some point before yours were produced.  Some people have used them by doing some file work on the corners.

  12. Hole size is decreased in 2018 Lascala II.  Not sure exactly what year they reduced the size.  First of the Lascala IIs used the K-77F with standard size horn used by all earlier K-77M tweeters allowing the entire horn to extend through the motor board with z-brackets.  Even after the change to the K-77D for some number of years the larger hole was maintained and earlier tweeters could be fitted to those holes using z-brackets.  As of 2018 (and perhaps some years earlier), only the K-77D could fit in the holes and no way to use the earlier K-77F or K-77M tweeters.  Attached is a picture of the K-77D installed in a 2018 Lascala II.

     

    Bob Crites

    K77D_in_2018_Lascala.pdf

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