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boom3

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    Show us your great photography thread!

    in Lounge

    Posted

    8 hours ago, dtel said:

    Thank you, we have never been but would love to go to Japan, but there garden pictures all looked way nice than ours, there amazing.  Japanese Maples are my favorite plants, had 25 different varieties at one time but lost most of then from dieback.

    If were ever up in the North West I want to visit the Japanese garden in Seattle 

    The Japanese garden in Golden Gate park in San Francisco is lovely also 

    • Like 2

    Audio Science Review of Heresy IV

    in Technical/Restorations

    Posted

    I like the ASR reviews because Amir is doing things no one else, certainly not Stereophile, is doing right now. He is using a consistent, defendable, set of metrics (no Klipschorns on stools in somebody's driveway) he is not using a lot of fluffy adjectives to puff up his advertisers'  products; and he can admit when he's made an error. His call-outs of  several examples of high priced trash audio products I am sure have made the manufacturers squirm. 

     

    I do share one concern about Heritage that both Stereophile and Amir point out-cabinet resonances. In all the uproar about Sterophile's bungled review of the Klipschorns, I did not see any discussion of the midrange cabinet resonances discovered. One would think that Klipsch could engineer these resonances to be lower in frequency and amplitude that the reviews have uncovered.

     

    Having said that I don't always agree with him or any other reviewer. His speaker reviews concentrate on bookshelf systems and has not tested many floor standers. His idea of perfect response is output declining with increasing frequency (like pink noise). I don't know why he thinks that is "perfect";  you'd have to ask him.

     

     

    Who made these midrange horn diffusers?

    in Ask the Historian

    Posted

    On 11/26/2020 at 10:26 AM, moray james said:

    I have a set based upon the same design principals on my JBL L200B though these used flat plates rather than curved ones. They do work to disperse as stated however I find that they mess with the stage and the image of the horn and as such I do not use them. I think had they been a success that you would have seen more in production and for a longer period of time.

    I might add that similar but more complex versions of this concept were used by Beveridge electrostatic loudspeakers to provide a flat panel with wide dispersion characteristics.

    for those who might be interested.

    https://patents.google.com/patent/US3668335?oq=Beveridge+electrostatic+loudspeakers

    Here is some JBL information on what they produced

    https://jblpro.com/en-US/site_elements/2301-2390-2391-2392-2395-information

    Thanks for finding the Beveridge patent. The original Beveridges were incredible speakers, and created a curtain of sound you could walk though, turn around and perceive the performance as if you were now in back of the performers. They are one of my two faves of all time (the Klipschorn of course being the other; have not heard Jubilees yet)

    • Like 2

    Who made these midrange horn diffusers?

    in Ask the Historian

    Posted

    They are acoustic lenses, developed in the 1940s to improve the dispersion of horns. As horn design became more sophisticated, the extra expense and appearance of acoustic lenses was no longer appealing, and they were dropped. I think only JBL really promoted them, but they may have licensed the technology to others.

    Happy Halloween during Covid-19?

    in Lounge

    Posted

    3 hours ago, Bosco-d-gama said:

    Sadly we won’t be accommodating Halloween 🎃 this year either. Too many in our community are intellectually challenged and many determine their own public health policies. We have no kids of our own and will just keep quiet and dark. This saddens us greatly as Halloween is one of our favorite events. Love to see the costumes and all the fun. Hopefully all will be more normal next year.

    That's us.

    In happier times, get a load of this from 1964:

    Scott and Lilibet October 1964.jpg

    • Like 3

    Cornwall Crites B-3 Recap

    in Technical/Restorations

    Posted

    The Equivalent Series Resistance (ESR) and Dissipation Factor (DF) varies between caps, so the capacitance value per se is usually not the significant factor . I recapped my B3s with WIMA caps and noticed no audible diff. I recapped really for long-term stability.

     

    Most electrolytic caps start out about 10-20% above their labeled value and then drift downwards, with ESR and DF increasing over time. Film caps of any type usually keep their values for life, although if exposed to heat from vacuum tubes or in a car, they can be damaged. I tested some 40+ year old caps recently, they were right on their 2% tolerance. I don't have an ESR or DF meter but I doubt these particular caps (CRC metallized polypropylene hermetically sealed) are much different from the day they left the factory. Mylar caps have higher DF & ESR than their poly brethren and therefore I avoid them.

    The difference between Moving Magnet / Moving Coil / Moving Iron Cartridges

    in 2-Channel Home Audio

    Posted

    B&O used a variant of the moving iron called micro moving cross, that had a cruciform piece of ferrous material that the stylus moved over the four poles of the coils and fixed magnet. It was most famously used in their SP-12 line. I had a SP-12A in my vinyl days and I loved it. It was slightly rolled off at the top, but with bright speakers it sounded very neutral. The test reports of the time noted its exceptionally low distortion.

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