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Pete B

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About Pete B

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    Advanced Member

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  • Location
    Connecticut, NE USA
  • Interests
    Interest in Audio for over 30 years, got started early
    Electrical Engineer (see my web site link)

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  1. I would guess that it can be changed but it would not be an easy job. I have a blown NLA tweeter that I believe was driven so hard that the insulation broke down and the voice coil shorted, then the current went way up and the red donut part of the cone was burnt brown under the tinsel lead in wire. I want to take a look inside and the red paper lip at the outer edge is already lifted about 1/3 of the way around. Not sure what to use to release the rest of the glue. Acetone or MEK perhaps.
  2. This is in the library as multiple .jpg s, does anyone have it in .pdf? I seem to remember seeing it years ago. It mentions measuring the DC resistance of the tweeter and tweeter inductors to test for burnout.
  3. Pete B

    OLAs again

    Here's 18 TPI Irish Linen: https://www.123stitch.com/m/18-Count-Linen-style-Cross-Stitch-Fabric Discussed many years ago in this thread: https://community.classicspeakerpages.net/topic/2884-advent-large-grillcloth-restorationreplacement/?tab=comments#comment-67500
  4. Pete B

    OLAs again

    I thought that someone found a source for very similar 16 count grille cloth. I don't remember where it was mentioned. There's 12 and 13 TPI here and they look close buy maybe not in real life: https://dorrmillstore.com/index.php/site/products/category/foundation_cloth/17
  5. You can try suction with a hose of the right diameter.
  6. Is boiled linseed oil usually that dark, or does it come in different tints?
  7. I'm aware t hat the original material cracked, but how do you get the tweeter guts out to glue into the new piece? Solvent? Heat? Crack it off? Anyone have the .stl file?
  8. Enter 40 uf and 1.37 mH into this calculator, and you'll find that they resonate at 680 Hz which is probably the fundamental resonance of the UMR: https://www.omnicalculator.com/physics/resonant-frequency-LC The L and C reactance cancel each other at resonance and you have a short (ideally) with a series resonance circuit or RDC of the L plus ESR of the cap at that frequency plus the 6 ohms in series. Call it 7 ohms which is probably the amount required to flatten the impedance, they might over or under compensate to shape the response curve as required.
  9. Sorry to be so late here updating Mine is also from B-A (something like Burnstein Applebee) without the electronics. I'd like to sell this unit for parts if anyone is interested.
  10. The "fan thing" is a heatsink, does it move with the cone? I'd guess that it is thermally connected to the voice coil.
  11. We can learn a lot by what is common and not, between them all: 1. 41-42 Hz closed box resonance (Fc) which is roughly low E on a bass guitar 2. Closed box Q (Qtc) of about .8 - .85 ish which makes the half space response less than 3 dB down at Fc 3. The OLA and NLA had only about 3mm theoretically linear Xmax (one way) and a huge Xmech of about 13mm. We can compute an overload headroom as 20 log(13/3) = 12.7 dB of overload headroom. 4. The OLA voice coil former is a very rugged brass/bronze looking type. The later versions had and aluminum type. 5. The
  12. Would you please tell us where you got the new domes in case anyone wants to repair an AR tweeter in the same way?
  13. I have several 12" Rectilinear III woofers with redish cloth edges and ceramic magnets that I'd like to sell if you are interested. Where are you located?
  14. What is the correct woofer for this speaker, make and model?
  15. Pete B

    EPI 100 Restoration

    I bought a used pair of Vandersteen 2 Ci s years after finishing college in order to reverse engineer them and hopefully improve my speaker design skills: https://audiokarma.org/forums/index.php?threads/vandersteen-2ci-design-overview-and-xo-schematic.913010/ Was not impressed with them. I became interested in the SPICA TC-50 when they came out years ago because of the rave reviews and linear phase design. I finally reverse engineered them years later, I'm not impressed with them: http://baselaudiolab.com/MR-TC50-REB.html I also reverse engine
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