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Pete B

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Everything posted by Pete B

  1. Bump, has anyone removed a tweeter for transplant? Also, does anyone know if there were any changes to the shape from the early AR3a to the last version? Pete
  2. Pete B

    Sad news

    Very sorry to hear this, he helped me several times by pointing out literature in the library. He was far too young. RIP Robert Pete Basel
  3. I tried to open them up here without much success. Is there a materials person who might know how the paper could be treated to make it less brittle? Or was it designed to be stiff and brittle from the start? https://audiokarma.org/forums/index.php?threads/disassembling-new-large-advent-nla-tweeters.953989/
  4. I'm a bit late here but very nice work. That is a very low Fc of 40.5 Hz with just the right Qtc. I documented the crossovers and listed the NLA woofer inductor with a much lower value than the OLA which has the powdered iron core inductor: http://baselaudiolab.com/ADVENT_LA_XO.html
  5. @Giorgio AR Those are nice pictures of the woofers. Does anyone know the correct part number for the AR-6 woofer? There is mention on here that the Xmax was quite high, higher than the other 8" woofers: Also was there a ceramic magnet version of the AR-6 woofer?
  6. 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.
  7. 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.
  8. 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
  9. 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
  10. You can try suction with a hose of the right diameter.
  11. Is boiled linseed oil usually that dark, or does it come in different tints?
  12. 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?
  13. 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. Note then that the 24 uF series cap forms a first order network to the UMD, which does not provide much attenuation at low frequency. I suppose that they get away with it due to the higher crossover frequency as compared to the AR-3a/AR-11. Is it correct that all of the drivers are in phase?
  14. 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.
  15. The "fan thing" is a heatsink, does it move with the cone? I'd guess that it is thermally connected to the voice coil.
  16. 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 tweeters are just OK, the NLA tweeter has an input impedance that is too low. If they were voiced less hot with more resistance in series then they might work good enough. 6. The Jensen design keeps the Advent bass (42 ish Fc and .8 ish Qtc, not sure if Xmax changed) but the crossover voicing is not as good IMO. 7. They all need baffle step compensation to sound truly HiFi IMO.
  17. Would you please tell us where you got the new domes in case anyone wants to repair an AR tweeter in the same way?
  18. 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?
  19. What is the correct woofer for this speaker, make and model?
  20. 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 engineered the PSB Stratus Golds and I do like them, great design but I never published the work other than the crossover schematic. I also helped a friend roughly "clone" them in the late 90s - he says he's never letting them go.
  21. Pete B

    EPI 100 Restoration

    @TheFrugalAudiophile I've always been interested in anything that can improve the listening experience and I became interested in "time alignment" and "linear phase" designs, sometimes now called "transient perfect" or "quasi-transient perfect". I went to hear the Dahlquist DQ-10 and always thought that they sounded good but never fully believed the hype about time alignment. This is a story that should give a laugh and pertains to EPI/Genesis: When I was in college I became a member and was reading the Audio Engineering Society (AES) Journal. There was a lot of hype in the press and an AES paper from B&O about their filler driver method for designing a "Linear Phase" speaker. I was lucky enough to have at least 4 HiFi stores within 15 miles of our home. One had the B&O speakers and I went there to hear them, in those days they offered an A/B switch and could patch in any two speakers. The young sales guy said sure I can demo the B&O speakers, here's a mid (high) priced model. I thought the bass is not even as good as Large Advents, and they were not at all musical. Then the kid says, do you want to hear some good speakers? I said sure, he patched in the Genesis 2 speakers on the B side of the A/B switch and said these are half the price. I was shocked bass significantly better than the Large Advents and a smooth, musical midrange and top end. I said I don't want to hear anything more from the B&O s and I could listen to these Genesis 2 s all day long. I never bought a pair, my big TL speakers were better but suggested them to others: https://community.classicspeakerpages.net/topic/3874-genesis-ii-rebuild-design-comments/ They are an EPI 100 in a bigger box, with a passive radiator: http://www.humanspeakers.com/genesis/gen2.htm I just in the last year or so added a pair of Genesis 2+ to my collection in real wood: https://www.humanspeakers.com/genesis/gen2plus.htm They compare very well to PSB Stratus Golds same deep bass but have about 6 dB less max output in the bass. Much simpler design and probably a sweet spot for cost/performance. There have been several scientific articles in the AES demonstrating that linear phase is not important to humans in the home listening environment and this demo drove that point home for me - B&O vs. Genesis 2.
  22. Pete B

    EPI 100 Restoration

    @TheFrugalAudiophile I started building speakers as a very young kid and read everything I could find about them. I read about IMF Transmission Lines (TL) and was very impressed with their bass performance. I tinkered around with them, built some that could shake the room with deep bass, and studied them as a senior project in college. My project advisor suggested that it should be possible to get as good bass as a TL with a vented system (ported or passive radiator). I did not have time to explore this but I believe that the Stratus Gold is a good example of how a vented system can provide as good if not better performance than a TL. The formula is a big box, low port tuning (Fb) and high port area for minimal turbulance (minimize compression) or a passive radiator.
  23. Pete B

    EPI 100 Restoration

    @TheFrugalAudiophile It is interesting that you ask what I listen to at home. I'm a speaker collector but one of my favorite designs is the PSB Stratus Gold. I always admired KEF 105 s and B&W 801 Matrix series II which I'll probably add to my collection someday. This is the B&W 801 that I admire but with the flaws fixed, pg 96 in the .pdf: https://www.americanradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1990-11.pdf The main flaws are that one of the iron core inductors in the woofer path saturates, it should be air core (no saturation), the woofer has DC offset issues "oil canning", all issues at high power. VanAlstyne also found that one of the woofer inductors couples to one of the midrange inductors - the simple solution is to desolder and move one of the inductors. Here is the Stratus Gold which has all air core inductors and does amazingly well in the high power testing, note also the very flat frequency response, page 50 in the .pdf: https://www.americanradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1991-11.pdf All of these systems are large and rather complex but take the listening experience to another level. I've A/B ed the OLA with the PSB Stratus Golds and while the Advents have deep bass the PSB s go much deeper and will play about 9 dB louder (a lot).
  24. Pete B

    EPI 100 Restoration

    @TheFrugalAudiophile I printed out and tried to read Holt's article. I like Holt he did a lot for critical listening and wrote some great reviews. I actually find that article hard to read because, in my opinion his logic is flawed. I have a very different perspective on audio, I prefer an A/B switch and a reference system. If you trust the reference, you'll quickly hear flaws in inferior systems and perhaps a system will sound even better than the reference but it makes it easy to remain honest. It is a very complicated subject due to placebo and expectation bias. I'll try again to read Holt's paper and see if I can put my objections into concise words.
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