DIY Audio Projects Forum

Virus Quarantine--time to work on speakers
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Author:  Joegtech [ 13 May 2020, 23:23 ]
Post subject:  Virus Quarantine--time to work on speakers

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.

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. ... 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. ... verity.jpg ... comes.aspx ... -mortality


Author:  JMRead [ 19 May 2020, 17:38 ]
Post subject:  Re: Virus Quarantine--time to work on speakers

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

Author:  Toobphonic [ 21 Jul 2020, 09:39 ]
Post subject:  Re: Virus Quarantine--time to work on speakers

Before Covid-19, I talked to a pharmacist about getting the measles vaccine. According to some articles I saw, if you get measles and recover, it tends to erase your immune system memory. Also, from reading old and new medical literature, I found out that measles, the flu and diphtheria can cause latent TB to turn active. 1/4 to 1/3 of the human race is infected with TB. About 4% of the US population has latent tuberculosis, which isn't contagious. Its only contagious when active. After finding some articles about the MMR vaccine appears to provide protection against COVID-19, I decided to get it. I got one dose in May and another in June. Adults are supposed to get their second dose 28 days after the first dose.

Homologous protein domains in SARS-CoV-2 and measles, mumps and rubella viruses: preliminary evidence that MMR vaccine might provide protection against COVID-19 ... 20053207v1 ... 1.full.pdf

The report MMR Vaccine Appears to Confer Strong Protection from COVID-19: Few Deaths from SARS-CoV-2 in Highly Vaccinated Populations reveals that nearly all countries with few or no deaths from COVID-19 have also had large measles-rubella vaccination programs in recent years. ... ation.html ... ation.html ... opulations

Coronavirus vaccines have been available for animals as far back as the 1950's

The researchers think these cells were likely triggered by past infection with one of the four human coronaviruses that cause colds; proteins in these viruses resemble those of SARS-CoV-2 ... m-immunity

Author:  Toobphonic [ 21 Jul 2020, 20:35 ]
Post subject:  Re: Virus Quarantine--time to work on speakers

Adults are supposed to get their second dose at least 28 days after the first dose.

Author:  Toobphonic [ 31 Jul 2020, 08:38 ]
Post subject:  Re: Virus Quarantine--time to work on speakers

Facebook and YouTube censored a video featuring "America's Frontline Doctors" calling out a "massive disinformation campaign" on the treatment of the coronavirus. The event was initially live-streamed on Facebook by Breitbart News and was removed by the platform after accumulating 17 million views within hours. ... rence.html

Note starting at about 22:45 where they show some psychopath in public ranting about keeping your Covid to yourselves, etc.
Silenced Frontline Doctors Hold Capitol Hill Press Conference to Challenge Big Tech

Doctors gather in DC
July 29, 2020

retracted article ... 6/fulltext

Author:  Toobphonic [ 24 Aug 2020, 08:22 ]
Post subject:  Re: Virus Quarantine--time to work on speakers


Author:  Toobphonic [ 23 Nov 2020, 12:32 ]
Post subject:  Re: Virus Quarantine--time to work on speakers

MMR vaccine and COVID immunity

I got the MMR II vaccine made by Merck.

The measles-mumps-rubella (MMR) vaccine has been theorized to provide protection against COVID-19. In a new study published today (November 20, 2020) in mBio, an open-access journal of the American Society for Microbiology, researchers provide further proof of this by showing that mumps IgG titers, or levels of IgG antibody, are inversely correlated with severity in recovered COVID-19 patients previously vaccinated with the MMR II vaccine produced by Merck. MMR II contains the Edmonston strain of measles, the Jeryl Lynn (B-level) strain of mumps, and the Wistar RA 27/3 strain of rubella. ... -covid-19/

Google MMR vaccine COVID-19
and you can find a lot of references.

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