JKent Posted June 12, 2015 Report Share Posted June 12, 2015 The Advent 400, for those who may not know, is a terrific FM-only radio from Henry Kloss after he left KLH. It is solid state of course but reminiscent of Kloss's first radio--the KLH Model Eight which featured an FM receiver with his signature vernier tuning dial in one box and a separate acoustic suspension speaker. Like all Kloss radios, the Advent 400 is known for its excellent reception. I've owned about a half dozen of these and they're impressive. The 5.25" full-range driver is the biggest of any Kloss radio and at some point they apparently used the famous Phillips whizzer-cone driver (but those are rare). According to Fred Pinkerton, Audio Product Manager for Advent, the 400 cost over $90 to produce although they sold it to dealers for under $110 and it had an MSRP of $125 (no wonder they went bankrupt). The tuner section, according to the Owner's Manual, "uses techniques and parts . . . associated with far more expensive receivers." Unfortunately, the cabinets are white polystyrene plastic that turns yellow with exposure to UV rays. The only way to restore the white is a painstaking process of sanding and polishing. One ebay seller paints them white but I was never a fan of the painted look or the possibility of scratching. YMMV. Another issue with these is low volume. Apparently some of the capacitors used--10uF axial leaded ones in the amp section--are known to fail. So.... this particular 400 worked but the volume was very low and the cabinets were just awful. I asked my favorite tech about the volume issue. I didn't want to take the radio to him because the repair would cost more than the radio is worth. He alerted me to the axial cap issue and implicated some other possible culprits. Also got some help over on AK. I replaced the four 10uF 16V axial caps with 10/25 radials (they had to be bent over to clear the pots) but there was no improvement (btw they all measured ~14uF). Went back in and found a 10/16 radial and pulled that. It read open! Bingo! Problem solved. Just to be safe though I replaced all the electrolytics on the amp board. Put it back together and it now plays LOUD! btw, all the 'lytics were about 40% out of spec. Maybe should have done the FM board as well. I did not replace the 1000uF 35v filter cap. It's a Rubycon and the radio doesn't hum so I left it. Couldn't measure that value with my cheap LCR meter. As for the cabinets, I've written before about using truck bed liner on old CSW speakers with the Nextel finish http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=7315 Thought I'd try that. It's truck bed liner, so it's rugged and there shouldn't be a problem with scratching. Results shown below. That's a before shot of the same radio--yuck! Not a "restoration" but these radios don't have that much collectible value. IMHO the pebbled black finish looks good. Also replaced the power cord for 2 reasons: I can use the original white cord on a KLH Model Eight restoration, and the black cord looks better with the black cabinet. -Kent edit: 2nd photo is new, showing truck bed finish Quote Link to comment Share on other sites More sharing options...
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