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4thtry
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- 4thtry
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Comments
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You should be able to set your gate at about 3.2ms. That should be fine.
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Based on your drawings and pics, I would suggest that your speakers appear to be too close to reflective room surfaces to get good measurements. What does your OmniMic impulse response screen look like?
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I was asked about the vertical dispersion pattern of the classic AMT tweeters operating in dipole mode, so I put together a few graphs. Since we are looking at a full 360 degrees, the heat map seems to be the best graph to use. This first graph b…
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(Quote) I was looking for blu-tack, but couldn't find it at local stores. So I picked up a pack of gorilla mounting putty instead. Probably very similar to blu-tack, just a different color and packaging. Seems to hold the diaphragms in position…
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Probably for cost cutting. Grill cloth is cheaper than wood.
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(Quote) I have noticed this too. In the past, I have mounted woofers on raw MDF using mortite rope caulk. Then, when I removed the drivers several years later, I noticed that the oils from the rope caulk had visibly stained the MDF a darker color…
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(Quote) So far, I have experimented with sealing the back with a 1/4" thick 6.75" x 8" sheet of closed cell foam rubber. Held it in place by press fitting it onto the back temporarity with gorilla mounting putty. Sounded horrible.…
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(Quote) My design will be completely open, front and back. A thin, narrow tower with the same footprint as the big AMT tweeter. Almost like mounting the big AMT on top of a pole. No nearby type reflections will be possible from the enclosure, …
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Thanks, Robert. Plan is to build a new tower system with them and have them ready for demo at Indy next year as my non-theme pair.
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(Quote) Got a reply. Apparently, any type of rope caulk, sold in the weatherstrip aisle of any hardware or lumber store, can be used.
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(Quote) I hear you!
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(Quote) Here is a link to my adventure down the 2 channel path. It was a fairly involved transition and took me a little time to adapt. But now I find it fairly easy to quickly set things up and take a set of measurements. https://diy.midwestau…
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I recently picked up a used Heathkit IO-4210 10MHz dual trace oscilloscope at a local hamfest. I have it connected in X/Y mode to a B&K 501A semi-conductor curve tracer, which I also picked up used at a local hamfest. I used it to test sever…
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(Quote) I found the thread when this "zero Z offset needed" with dual channel measurements thing was discussed. It was on page 9 of the "indiyana-2022-missing-link-theme-announcement" thread as follows: https://diy.midwestaudi…
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Wait. I need to correct myself. Since time of flight is eliminated with the dual channel setup, there is no phase rotation that needs to be corrected. You should therefore NOT have to add 6mm to align the T+M summed response. This problem ca…
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That is odd. Maybe the phase rotates exactly 360 degrees and therefore appears to need no Z offset (just a guess).
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(Quote) Based on my understanding of how all this stuff works, I would say yes, this is normal. But this is only because you are taking your measurements from a fixed microphone position relative to each driver. The midrange is therefore further…
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Before Heathkit recap: (Image) After Heathkit recap: The vintage HP distortion analyzer: (Image)
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Thanks for the kind words, Ron. Glad to see it working again. I really enjoyed repairing it for you. And thanks again for the vintage HP distortion analyzer. I plan to do a full restoration on it and put it to good use on my test bench. When …
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Nice. 55 clamps. Beats my collection of only 22. I need to build something like this. And get more clamps.
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I removed the melted, 50 year old diaphragms and installed the two NOS (new old stock) diaphragms that @LifeOfBrian gave me. These diaphragms look like the yellow or bronze colored teflon ones that ESS sold as replacements many, many years ago. …
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Excellent match. And really smooth looking for a 25dB/decade plot.
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(Quote) Thanks for the offer, Ron. I picked up a pack of gorilla mounting putty and I think I will give this a try first. Its very soft and tacky and easy to remove, leaving no residue.
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I went back and edited several of my earlier posts in this thread to make it clear that I am measuring a very old set of classic ESS AMT tweeters from the early 1970's. Not a new set of ESS AMT's like many others are testing. The diaphragms in t…
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(Quote) I'm no expert, but based on my limited experience with this driver and diaphragm, those impedance curves look perfectly normal to me. The newer diaphragm used on these is spec'd at 3.7 ohms DCR. That matches your curves almost perfectly. …
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(Quote) Thanks, Nick. The web site lists Simply Speakers as an authorized dealer for replacement parts, so I submitted an email question and am waiting for a reply.
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(Quote) 12 lbs on my uncalibrated bathroom scales! B)
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(Quote) These are a vintage pair from the early 1970's. Still going strong, but the pleats are getting a little tired.
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(Quote) No. There are several threads on Audiokarma and diyaudio talking about swapping these diaphragms, but noone ever seems to mention the type of putty used. So I am on my own on this one. I've decided to try a "no residue" type …
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I pulled the damaged diaphragm out of the tweeter that I am calling "A" (classic 1970's ESS AMT). Below is a side-by-side comparison with two other diaphragms. The left most is the damaged "A" one. As you can see, It is bad…