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Pete B

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About Pete B

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    Advanced Member

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    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. Very nice! Did you use a template for the woofer recess?
  2. I had one SA woofer that had been powerfully overdriven, easy to do with 200+W/ch, with the VC former hitting the back plate and bending. Here is a thread where I repair it better than new, you might have to join Audiokarma to see the pictures: https://audiokarma.org/forums/index.php?threads/small-advent-woofer-repair-some-measurements.819443/ It was easy to remove the cone because the old glue cracks easily pressing down hard on the spider at the joint.
  3. The glue work on those old woofers was not done very well back when they were made. Check them all by applying pressure to lift or move various parts. The gasket, the dust cap, the spider to voice coil joint, everything. Here is an example on an EPI-100 but the idea is the same:
  4. Pete B

    EPI 100 Restoration

    Found some newer (to me) Playing for Change tunes and made a playlist here that I've been listening to:
  5. Pete B

    EPI 100 Restoration

    Hi Robert, Those look very nice, I've never seen the rubber edged version in real life and I wonder if there is any difference in the sound. And thank you for the nice comments. Pete B.
  6. https://audiokarma.org/forums/index.php?threads/epi-100w-foam-popped-woofer.633766/
  7. Pete B

    EPI 100 Restoration

    I've been listening to them all afternoon today and I never owned a pair, never saw an input impedance plot, my guess was that they'd have an Fc of 60-70 Hz - what a surprise with the Fc at 49 ish Hz. They really have nice bass depth and impact, not as good as Large Advents but very close. They sound very smooth and balanced with the L-pad straight up (about 3 ohms in series with the tweeter). Nice detail provided by the extended response of the tweeter. I'm really enjoying these. They are placed high in the room, on top of LAs that are also on low stands and they sound like they could use a dB or two of baffle step but this might also be fixed by placing them on a low stand closer to the wall. My younger son commented that they sound a bit, just slightly flat (as in depth), and this indicates not enough baffle step. Overall he liked them very much. I've said before that these are one of the best sounding American made vintage speakers period I wish that they did not need a sub and the Genesis 2 is the answer to that issue providing response into the low 30s.
  8. Pete B

    EPI 100 Restoration

    It is interesting that these are rated as 4 ohm DC and 8 ohms nominal which is stretching the truth a bit. They certainly are 4 ohms DC and then dip to below 5 ohms in the bass and about 6 ohms in the mid treble. The woofer Thiele and Small parameters are now posted in the woofer repair thread and it is clear that these are true acoustic suspension woofers. I was very curious to measure the woofers in the closed box system. Here are the results: Rdc = 3.95 3.94 ohms Fc = 48.4 49.5 Hz Qtc = .90 .96 I was surprised to find a low Fc of just below 50 Hz and with Qtc being .9 ish they should be down about 1 dB at 50 Hz, nearly flat. I'd guess that the 45 Hz rating is -3dB. Here is the input impedance for system PLB-1: And Zin for system PLB-2:
  9. Pete B

    EPI 100 Restoration

    I'm keeping these in my collection.
  10. T&S measurements, posting a picture because the forum strips spaces and makes it difficult to format a table: Note the very low Fs and large Vas indicating that the filled fillet foam has very high compliance as it should: Parameters pass a sanity check and pair matching is good:
  11. Pete B

    EPI 100 Restoration

    I solder directly to the threads of the binding posts in order to provide a gas tight connection to the posts. The woofer (black) and tweeter (yellow) grounds are soldered to the negative post, an extra black wire is also soldered to go to the ground terminal of the L-pad. A 10 uF 1% Dayton poly cap connects from the positive post to the input of the L-pad, the woofer positive (red) also goes to the positive input post. The cap is glued down with E6000. Tweeter positive (red) is wired to the center terminal of the L-pad. The picture is blurry and while the solder joints look cold they are actually well done. All connection are hook type for mechanical strength, then soldered: Used the stock wire, but soldered the wires to the slip on terminals. Clean the brass first with a nail file or sand paper. This shows bare wire past the crimp bent back over and soldered: Other times there is some bare wire right below the crimp where it can be soldered: I might use these for testing drivers but, obviously, one could snip off the slip on connectors and solder directly to the drivers. Give the slip on's a shot of DeOxit for long term stability.
  12. Pete B

    EPI 100 Restoration

    This is what the stock, cheap binding posts look like: I gripped the plastic push terminals with pliers and twisted about half a turn back and forth about 10 times, then just twisted hard until they broke off. You can't be sure if this will work so don't do it unless you are okay with replacing the entire terminal. There are 3 slots that held in the old posts and the outermost ones are at exactly .75" spacing which is correct for dual binding posts. I drilled them out for a tight fit to the Big Post (from Madisound) hex binding posts: The terminal board is very thin at about 1/16" and the masonite is only 1/8" so I decided to back it up with a 4X5" piece of 1/4" MDF. The crossover board was not glued in with much glue so I ran a bead of carpenters glue over it. Drilled the Lpad hole through both boards and glued the 1/4" backing MDF to the now cleaned off and blank crossover board. I also filled the empty hole around the back of the binding posts with epoxy wood filler, had the type that you slice off and knead handy to fill the two remaining slots and give the new posts a more solid base: And with the Lpad to clamp the boards together: Finished close up, knobs are not needed but Radio Shack 274-0403 1/2" blue look nice and are still available on ebay: Put the knob on so that full up is at 3 o'clock, then up should have the right tonal balance for most people, full off is never used and 9 to 3 o'clock is the useful range. Dual binding posts fit perfectly:
  13. Pete B

    EPI 100 Restoration

    I've always wanted a pair of EPI 100's in real wood veneer and a pair came up locally in nice outside condition. When I pulled the grills one woofer had the cone popped out about .5" or more. The amp had gone DC and that completely tore the spider to VC former glue joint. I covered repair of the good woofer and a replacement in this thread: http://www.classicspeakerpages.net/IP.Board/index.php?/topic/10671-epi-100-woofer-refoam-and-glue-joint-repair/ I tested some of the older masonite faced EPI tweeters here and found temperature dependent behavior: https://audiokarma.org/forums/index.php?threads/epi-inverted-dome-tweeter-issues.824827/ These tweeters tested without problems and I'll add the results to that page when I have a chance. This is essentially a stock restoration with a lot of attention to detail. These match the below pair pictured on this page but with foam edge woofers rather than the rubber ones shown. Also note that the early EPI-100 had a level control on the tweeter, these do not have them but I am adding 50W Lpads (from PE) because I know that they sound better with some tweeter attenuation. Two schematics are shown here, one with just the standard 10 uF cap and another with the cap and the 5 ohm rheostat. Note that the drivers are wired in phase: http://www.humanspeakers.com/e/epi100.htm Everyone wants pictures so here are a few of the finished speakers: Front, note the correct filled fillet foam on the woofers: Back, I didn't bother to clean the old glue residue but I did add a 50W L-pad and upgraded gold binding posts: Front, the grilles are near perfect but I'd prefer white Irish linen from 123 Stitch, perhaps someday:
  14. I've always wanted a pair of EPI 100's in real wood veneer and a pair came up locally in nice outside condition. When I pulled the grills one woofer had the cone popped out about .5" or more. The amp had gone DC and that completely tore the spider to VC former glue joint. Desoldered the lead in wires from the terminal strip and that allowed me to completely remove the moving parts from the woofer. Interesting to note that the VC former is paper rather than a thermally conductive metal. I've been informed that the Genesis version of this woofer has an aluminum former and I'll be looking for those woofers. More discussion here: https://audiokarma.org/forums/index.php?threads/epi-100w-foam-popped-woofer.633766/ Obtained another EPI 100 woofer and refoamed it with filled fillet foam, looks good at first: On further inspection I noticed that very slight pressure on the spider moved it at the glue joint to the former. This picture shows the normal gap where about 1/16" of VC former paper can be seen: Next picture shows the gap at about 1/8" with slight pressure from my finger indicating that the joint needs to be reglued: Note also, that the Original Advent woofer and many others often require this type of repair if they are to be used at full output: I use JB Weld 2 part epoxy for this type of joint for the strength, ability to withstand high temps, and availability locally. A shish kabob wooden skewer is just the right shape to apply the glue without it getting on the spider. I apply it in small amounts working it into the spider and cone at the joint: Once the epoxy was applied the wide 1/8" gap did not want to close up. I had to put the woofer face up on a table and put a weight on the cone to force it down and close up the gap - left it overnight to dry. I hated to do this since it caused the spider to sag, but the alternative is to scrap the woofer. Some might try to rebuild it with a new spider but most replacements are often not compliant enough: The glue is very slow drying and I had to leave it over night. The spider rest position was lower than normal after sitting for so long. I use rolled up shopping bags pushed between the frame and cone to push it out and leave it overnight to restore the correct rest position: Note how the cone is at the full out position with the bags in place: Completed job, note how the spider is flat again. The spider should always be checked for flatness in case any previous handling might have caused spider sag: I had epoxy glue left over and used it to apply a layer on the magnet over the original glue, not pretty but it should help: Some like to apply damping material on woofer frames and commonly available U-Seal is cheap and easy to apply: I'll measure these some time soon.
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