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across the bench: an electronic menagerie of diagnostic oddities plus photos and design analysis

jolida 302a EL34 - 9.jpg
highest output before distortion at 100hz into 8r resistive load was 23.5v rms (69w rms, ready to rock the house). testing a single channel since both will no doubt measure lower due to the 300va mains txf limitation.

technically this could be overcome by offloading the heater taps onto an external/secondary supple (3 taps at ~6v each) plus add a scrap 12v fan for increased air circulation inside main chassis. which would free up some extra wattage for the mains txf.

but there is only so much that should be squeezed out of an EL34, so focusing on output quality since quantity is more than sufficient should be the next consideration. hello wide wide world of signal caps...
 
www.humblehomemadehifi.com

Humble Homemade Hifi - Cap Test

Humble Homemade Hifi - Very high quality loudspeaker kits, components, upgrades, modifications and custom solutions.
www.humblehomemadehifi.com www.humblehomemadehifi.com
*there are some cost effective options for the jolida 302a that rank high on this persons objectivity scale.

x4 0.22uf 600v currently (phase splitter outputs), upgrade rated for 800v
x2 0.47uf 600v currently, upgrade to 800v (400v mod will need some on/off dc measurements)

800v rating for 0.47uf unnecessary for the circuit position (overkill improves lifespan though)

ClarityCap PUR/PUR-S series

Hi guys, I would like to know if anyone here tried the ClarityCap PUR version capacitors? How would you rate the PUR against the Jantzen Silver Z-Cap or Jantzen SuperiorZ-Cap? Also there is a PUR-S version, is there any noticeable difference from the PUR version? Could not find any review...
www.diyaudio.com www.diyaudio.com
*apparently i am not the only one comparing claritycap pur-?? vs jantzen

would be a good idea to establish a price per cap limit and identify a point of minimal gain vs price. an example would be 25usd/cap for a score of 10 vs +80/cap for a score of 11, definite go with the lower cost.

there is a motorola 2.1 tube amp coming up soon with EL84 config (L/R single ended, center push-pull). not sure its worth doing a clean sweep of updates and upgrades... a self inflicted diy design involving multiple 12at7 is lurking in the mental background as well. plus some r&d power supply designs for tube systems, too many ideas.
 
pioneer cs33 - 1.jpg
another feather weight speaker like the sansui earlier, pioneer cs-33

pioneer cs33 - 2.jpg
in good condition but need to take a look inside
 
pioneer cs33 - 6.jpg
whats behind door number 2 i wonder, its a rat (rat shack / radio shack)

pioneer cs33 - 7.jpg
the non-original driver does show that a standard 4 or 8 hole pattern speaker can be a drop in replacement. oddly enough the grs woofer might weigh as much as the entire speaker cabinet with tweeter. have to look around at what other options are collecting dust in the warehouse.
 
douk a5 pro mod - 1.jpg
quick experiment with the douk a5 pro. adding a parallel power cap to see if output performance is impacted favorably. dont have an fft yet thats decent to evaluate if sinad improved or lower noise floor.
 
douk a5 pro mod - 3.jpg
bumping up the 3300uf with an extra 3000uf

douk a5 pro mod - 2.jpg
screw terminal cap rated for 3000uf 75v. the screw terminals are perfect diameter for banana terminations (dmm probes: banana to mini-clip).
 
douk a5 pro mod - 4.jpg
no change in output wattage when adding the extra cap

douk a5 pro mod - 5.jpg
even the slightly distorted peaks are unchanged. spectrum/fft analysis might show a reduced noise floor but i do not have an easy/accurate of measuring it. this is where having a quantasylum qa403 would be nice.
 
kef r300 - 23.jpg
svc-mf+sp1632 for the kef r300 (midrange+tweeter assembly)

www.tonepublications.com

KEF R300 Bookshelf Speakers

Full-line speaker manufacturers, like Focal, B&W and the brand featured in this review, often deliver the most bang for the buck in the middle of their product ranges. These products may not have the ultimate performance of the flagship, but they don’t cut corners either, as can often be the...
www.tonepublications.com www.tonepublications.com
 
kef r300 - 26.jpg
tangerine wave guides look ok

kef r300 - 27.jpg
voice coil and spider look like there are no changes/improvements. newer driver has two stickers.
 
kef r300 - 28.jpg
both newer drivers installed and now there is perceivable high frequency response. diameter of magnet vs diameter of cabinet hole are a little too tight hence the half moon cutouts to allow two pairs of connection wire (one cutout per wire) in and out of the cabinet, not a good design.
 
*apparently a few things happened with audio research co, somewhat recently

www.ecoustics.com

Audio Research Has a New Lease on Life

AR Tube Audio Corporation has purchased Audio Research at a critical moment and saved the legacy high-end brand from extinction. Acora Acoustics' Valerio Cora is the hero of this story.
www.ecoustics.com www.ecoustics.com

cant say that i am up to date with big name companys and there ups and downs. gentex acquiring klipsch and associated brands in its group was interesting to see. not to mention bose pulling in mcintosh and making mit a protector of the brand vs the usual vulture capitalist firms trying to make a criminal buck or two.

www.audioholics.com

Bose Acquires McIntosh Group

Bose acquires McIntosh Group, home to McIntosh and Sonus faber, stepping into luxury audio. A bold move, but what’s next for these iconic high-end brands?
www.audioholics.com www.audioholics.com

news.mit.edu

MIT announces 2024 Bose Grants

MIT announces its 2024 Bose Grants supporting bold research projects, including clean hydrogen retrieval, monitoring fetal health through acoustic fabric, basalt monomaterial architecture, and ocean oxygen sensing via shark.
news.mit.edu news.mit.edu


» Fred T. Bauer | Automotive Hall of Fame

www.automotivehalloffame.org www.automotivehalloffame.org
*cant say that i have met fred in person but did spend time at robertshaw after a few renaming/rebranding activities were transpiring. and then the end game parent company shut down the location, sent engineers to carol stream illinois and all production went to... mexico.
 
tripp LC1200 - 2.jpg
internal board and it has a pot that might be useful

tripp LC1200 - 3.jpg
adjusting the pot sets the over-voltage threshold of when the txf clicks to a lower voltage tap. normally around 125v steps down to 115v to protect electronics from higher than normal line/mains voltage.
 
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