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It is currently 30 May 2020, 11:00

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PostPosted: 13 May 2020, 23:23 
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Joined: 23 Feb 2020, 21:08
Posts: 11
One positive about the virus is that I've had more time to catch up on speaker rebuild projects that have been in waiting.

I was trying to document the frequency response of my speakers using some old mics I had around my old basement home recording studio. I discussed my early attempts here.
viewtopic.php?f=11&t=6731

I finally picked up an inexpensive Dayton EMM-6 calibrated mic with a custom calibration file. I've been using it with the REW app to rework some speakers. I'll eventually use that mic to create cal files for a few of my other mics and will sell at least one of them. I'll eventually document that work in the discussion above.

I picked up a couple of low cost Class D amp boards to power two small subs that I'll use in small 2.1 setups at home. One project is finished and worked well for my modest needs--background music in the bedroom.

I blew the 15 inch woofer in a 20 year old self-made stage monitor. It was a Radio Shack woofer with a foam surround. I had not used it in a few years. I should have pulled the screen to inspect it. It is an known issue with that woofer. A pair of replacement surrounds go for $25. So now I'm facing a rebuild : (

That old woofer's frequency response seemed to fade out gradually at its high end without a bump. It was a nice match with a piezo tweeter that Radio Shack had back then. It sounds nice without a crossover.

However so many other woofers have a bump in the upper mids at around a reasonable spot for a crossover. Some of the bumps even have a curve that looks excellent for a 2nd order crossover. The crossover should flatten the bump then cause an even steeper cutoff.

Have others noticed the bump in other woofers that seem to be designed to work well with a 2nd order crossover or is this more likely a coincidence?

I picked up some dome tweeters for another project to upgrade speakers without a front grille. So I need 4" outside diameter to preserve the appearance of the face. I purchased some Goldwood units from Parts Express but have been having trouble getting a set that make a good pair. Frequency response for the soft domes have not been very similar. However I have 4 Goldwood metal domes are just fine. They all make good pairs. I documented my saga here for obvious reasons.
http://techtalk.parts-express.com/forum ... eter-pairs

Is there something about soft domes that make manufacturing consistency more difficult than in metal domes?

The down side of all of this is that I'm not getting outside much to pick up sunlight for vitamin D. According to some studies Vitamin D blood levels correlate fairly well with virus severity.

In one of the studies almost everyone who had a "mild" case had healthy vitamin D; whereas almost everyone who had a "severe" or "critical" case did not have a healthy vitamin D level. I think the article at the second link below touches on the implications for people with dark skin as well as the elderly.
https://media.mercola.com/ImageServer/P ... verity.jpg
https://articles.mercola.com/sites/arti ... comes.aspx
https://childrenshealthdefense.org/news ... -mortality

Joe


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PostPosted: 19 May 2020, 17:38 
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Joined: 18 May 2020, 17:10
Posts: 6
Interesting about the Vitamin D didn't know that, we have a small side garden and we grow a few veggies and flowers there. It all takes time outside but we do soak up lots of D most days.

Thanks for cheering up another old fogie

Cheers - J


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