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Pete B

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About Pete B

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    http://www.linkedin.com/in/petebasel
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    Male
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    Connecticut, NE USA
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    Interest in Audio for over 30 years, got started early
    Electrical Engineer (see my web site link)

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  1. What speaker did you compare against, many are voiced far too bright in my opinion.
  2. It really helps to have a modern reference to compare a vintage design agaist before and after changes, or to measure them.
  3. No, I did not measure the acoustical response and it is assumed to be completely flat and this is why the responses are the electrical crossover only. The total response is the cascade (complex multiply) of the electrical and acoustical responses. The acoustical response is fixed so this is the change to be expected between settings.
  4. Here is a simulation of the AR-11 mid network S1 is the normal .88 mH inductor with .35 ohm DCR, S4 is with a .88 mH with only .01 ohms DCR, both are 0dB level. The LF rolloff can be seen to maintain the slope below 100 Hz with lower DCR for the inductor:
  5. Here is a larger zoom of the frequency response curve: Note that the rolloff, as expected, is about 12dB/oct around 200 Hz, but it approaches 6 dB/oct well below 100 Hz, this is due to the DC resistance in the .88 mH shunt inductor.
  6. I measured the input impedance of the AR-11 drivers many years ago. Recently remeasured the midrange and decided to take a look at the crossover frequency response in simulation for each of the switch positions. I used the AR inductor values including DC resistance and estimated the NPE midrange cap ESR at .1 ohms, the simulator allows these values to be included in the component model but I decided to show it for the caps and not for the inductor: S1, red, is the 0 dB or max output switch position, it is not very flat and there is peaking in the network response around 3KHz. Curve S2, yellow, is the -3dB position and shows a reasonably flat response. S3, black, is the -6dB position with a very flat response and quite a bit of droop below 1 KHz. I thought that the -6dB position sounded best but would have preferred something between -6 and -3dB. S4, brown, shows the response of the AR-3a network set to the dot position, the .8 ohm series resistance is the .5 ohm resistor with .3 ohms added for ESR of the large wax box capacitor. This was my estimate and I found a value of .27 ohms in the AR-3a restoration manual - close enough. The impedance curve shows the input impedance of the midrange driver alone which is important since it loads the crossover network.
  7. Pete B

    Early AR6's

    I'm wondering what is the correct dimension for voice coil exposure at rest for an AR-2ax woofer, anyone know? That is a good way to check if the VC rest position is correct.
  8. Pete B

    Advent Tweeter Comparison

    The only catenary dome tweeter that I know of is from Audax.
  9. Pete B

    What type of load is the AR10Pi ?

    Do we have input impedance measurements for all the old AR systems? 10Pi, 11, 5, 2ax, etc. I have the AR3a but I think that it is for the early version only not the later.
  10. Pete B

    AR-5 crossover

    I'd completely recap them if they were mine since if a midrange or tweeter cap becomes leaky it could blow your expensive mids and/or tweeters. Save the Spragues since they seem to age well and someone might have a use for them. Obviously you'll want to clean and/or replace the pots and put the crossover back to spec. There are probably enough pics and schematics on here to easily do it. You can search at Google for AR-5 then look under images to find pictures that might help: http://www.classicspeakerpages.net/IP.Board/index.php?/topic/5203-ar-5s-singing-with-roys-help/
  11. Pete B

    need help w/ AR5 crossover

    I agree that you should start a new thread so that people don't have to think about reading all the history in this thread.
  12. Pete B

    AR-12 crossover

    Thanks Robert
  13. Pete B

    AR-XA in box?

    I have an SL- 1200 MKII with no mods at all, and don't expect that I'll ever spend that much on an SP-10. I never looked into the history, thanks for the info and writeup.
  14. Pete B

    AR-12 crossover

    Anyone have a link to this schematic, the above one no longer works?
  15. Robert, ra.ra kindly provided this drawing of the 200044 1.5" midrange that was used in the AR-58s. It includes ferro fluid and does not include a screen or front fiberglass pad but otherwise is likely the same, can anyone confirm this? The older mids did not include the glued on "Semi-horn", item 10 in that drawing. The diagram mainly provides construction details and notes but does not include actual dimensions or tolerances. Still a great diagram. 200044.tif
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