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Pete B

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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. I wonder how this Visaton paper cone tweeter with a smooth response would do as a replacement, with a parallel resistor to match the impedance: https://www.mouser.com/ProductDetail/Visaton/TW-70-8-Ohm?qs=VWNNG7jHlrLkQoY0VZlmUA%3D%3D Mounting would have to be worked out, perhaps 3D printed.
  2. Dear Pete B,

    I am writing because some of my internet searches over the years have taken me to your posts on the Classic Speaker Pages forums. Thank you for your contributions.

    My interest is in building a pair of speakers similar the the EPI 150 or Genesis Model II using parts available from Human Speakers (Human Models 81 and 81-10, respectively). I would build the EPI 150/Model 81 to the internal volume of 1.5 ft3 and the Genesis II/Model 81-10 to 1.8 ft3 as recommended by Huw Powell of Human Speakers.

    https://www.humanspeakers.com/diy/81.htm

    https://www.humanspeakers.com/diy/8110.htm

    I understand this question is subjective but I would like to know which of the above you would recommend based on the following:

    1. My room size is 10’ x 15’.

    2. My amplifier is conservatively rated at 40wpc/8 ohms and I doubt I would ever listen above 85dB.

    3. I want speakers for two-channel music only without a subwoofer. However I do appreciate low bass as intended.

    4. My music choice is primarily progressive of classic rock from the 70’s and 80’s such as Yes, Genesis and Mike Oldfield.

    Thank you in advance for your help!

    Rick H

    Onkyo A-5VL Datasheet.pdf

  3. Next year this thread will be 20 years old, time flies!
  4. As the title says don't want to ship but will try to figure something out if further. Anyone? Don't mind doing a few or more repairs.
  5. Hi Pete,

    I just did a recap of Dynaco a25's which included your 1uF mod. Luckily I have two pairs so could A/B with the an original crossover. As expected there is a very nice increase in the top end and the addition of "air" as you say. The original cap was 4.7uF. It measured 5.2uF when removed. I replaced it with parallel 3.3uF and 1.8 uF Jantzen Standard-Z caps.

    Would you have a moment to quickly explain the effect of the 1uF cap? My electronics is getting better but I'd like to hear your thoughts.

    Thanks very much!

    a25 new.jpg

    a25 old.jpg

    1. Pete B

      Pete B

      The tweeter level control provides some resistive attenuation.  Remember/consider that a cap passes

      high frequencies and the addition of the cap provides a path for the highest frequencies to in a sense 

      bypass the resistive loss.  It can only lift the same amount that the resistors are attenuating so as you

      turn up the level the effect will be less.  You can bring the HF bypass to pass at a lower frequency by

      increasing the size of the cap.

    2. sfoster137

      sfoster137

      Thanks so much for your reply Pete. I'm only seeing this now after a recent post I made concerning AR-5's. Yes, I've been reading about the bypass cap and this was a very obvious sonic change...not to mention the new 5uF film cap I also installed. I did read that some suggested the 1uF should have been .1uF and the "." was possibly omitted in the document. Perhaps you could confirm.

      Thanks again.

    3. Pete B

      Pete B

      I don't know where anyone made that comment but they are wrong it is 1.0 uF.

  6. Pete B

    OLA refurb

    I have a pair of LA woofers here that were refoamed by Bill LeGall of Millersound about 6 months ago and there's no sign of the dust caps being removed.
  7. Pete B

    OLA refurb

    If you found an 8 ohm SA woofer I'd say that it was probably worked on with a VC replacement or they mixed up some LA woofer voice coils in with the SA ones. It is in the "engineering" sales literature that while they SA maintains the same F3 as the LA they lowered the impedance to 4 ohms in order to keep the system voltage sensitivity as close to the LA as possible. However, even the LA is lower than 8 ohms with the DCR usually measuring under 5 ohms. When I worked on a few SA woofers I was surprised how similar, if not the same the magnet pole piece, VC were to the LA, probably a parts commonality thing for mass production. I repair two SA woofers here with some notes: https://audiokarma.org/forums/index.php?threads/small-advent-woofer-repair-some-measurements.819443/ I measured a DCR of 3.3 ohms for the SA woofer.
  8. They look like Advent Legacy woofers with very large replacement dust caps.
  9. I discuss a bit more about the presentation in this thread: https://audiokarma.org/forums/index.php?threads/presentation-at-frankenfest-4-1-2023-why-waveguide-speakers.1026720/#post-16319058 I measured the LA Econowave here and found a few serious issues that are corrected in the PB1 modded version that I'll be demoing: https://www.audiokarma.org/forums/index.php?threads/measuring-the-jackgiff-bauhausler-jb-large-advent-la-econowave-2022.1006729/
  10. Giving my presentation "Why Waveguide Speakers?" and demo of the Large Advent Econowaves at the 2023 Spring Blue Mt. Audio fest. Peekskill, NY Tomorrow Saturday May 6, Doors open at 10 AM presentation at 1 PM or so, playing it by ear, very informal. $20 fee, also audio gear swap meet. Blue Mountain Park, Welcher Ave. Peekskill NY https://audiokarma.org/forums/index.php?threads/%E2%99%AB%E2%99%AB-saturday-may-6th-2023-spring-blue-mt-audio-fest-peekskill-ny-%E2%99%AB%E2%99%AB.1025956/
  11. I use a 10 ohm resistor so it is about half the voltage at the speaker. One thing I should have mentioned is that the rubber edge could have hardened, though mine looked fine. It depends on the type of rubber and I have many woofers with rubber edges that have Fs now that is 2X what it should be. Wintergreen oil is talked about a lot on the Web and Youtube and it works great for a day or 3 let's say. Doesn't take long for them to be back to 2X. I will probably try brake fluid next time being careful not to get it on the glue.
  12. I was given some very beat up large Advents, did some repairs and did a lot of sanding thinking I'd just apply a new finish. I found the same thing, that sanding, even the first layer produced a lot of colored dust. What I found was that the front trim was not even close to the rest of the cabinet. And the cabinet had large color variations. It seemed to me like there was a tinted clear coat and after doing some research I found that this was common since the 1940s to even out the color and I'm quite sure that it is what Advent did. I think that AR's used a better quality wood and perhaps this wasn't needed but it is something to keep in mind. Certainly, if the owners manual says it is finished with BLO and that's what to use to freshen it up, then that's what you should do. Please keep us up to date since It might help with my effort. These were almost ready for the dumpster so I consider it a learning experience. I'm considering trying a black dye/stain just to get the job done.
  13. Great that you already rebuilt them! Yes I'd add the shunt cap but no rush. Hope you enjoy them very much.
  14. Your tweeter impedance certainly looks to be 4 ohms. That is of each series-parallel array? If they all work, I would just use them and listen for distortion in case any of them have problems. Perhaps they were already rebuilt with 4 ohm coils? Both arrays have an impedance peak around 4KHz which is very high and makes them super tweeters. Most of those tweeters that I've measured, perhaps were worn out, did not show much of a peak at all. I don't know what the correct impedance peak frequency is for those tweeters. As far as caps go, I would replace the tweeter and mid caps as soon as possible. I prefer film caps because I don't like to have to change them every 10-20 years. I'd probably replace the cap across the woofer with an NPE. The large input cap I'd check for leakage and it might be okay, otherwise you might want to replace them with new. See how they measure for leakage and how they sound.
  15. If you decided to build the 16/8/3 then the DCR is lower, you have to tell us what you decided to do.
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