Post by colinf on Jun 23, 2017 11:19:30 GMT 12
It was meant to have been designed for the Fisher SA-1000. Philips also used it in the 8417 mono amp. Also a few guitar amps.
AMR-iFi R&D
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Post by guitardude on Jun 23, 2017 11:22:16 GMT 12
The quicksilver was the only amp i'd ever heard of using the 8417. I have a faint recollection that my Fisher 500b used 7591 ? Which were almost unobtainable for a time before resurfacing as Chinese manufactured items !
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Administrator
 Post by Owen Y on Jun 23, 2017 11:42:20 GMT 12
Designed by Sylvania I believe, for hi power audio.
Also used by US amp makers, Bogen, Dynaco,...they say.  DarkLantern blog - darklanternforowen.wordpress.com
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Post by colinf on Jun 23, 2017 12:06:37 GMT 12
It would be good if it could be re-made. JJ?
AMR-iFi R&D
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Post by michaelw on Jun 23, 2017 12:50:49 GMT 12
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Post by colinf on Jun 23, 2017 18:36:07 GMT 12
The 8417 transconductance is 23ma/v and triode gain mu=16.5, anode dissipation 35w, with 1.6A heater current.
Compare that to 6550: 11ma/v, mu=8, 42w, 1.6A heater current. The EL34 has: 11ma/v, mu=11 and 25w anode dissipation, 1.5A heater current. A single 7591 has 10ma/v, mu=16.8 and 19w with 0.8A heater current. So paralleling 2 would yield comparable results to a single 8417: 20ma/v, mu=16.8, 38w anode dissipation and 1.6A heater current. AMR-iFi R&D
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Post by beeman on Aug 6, 2017 3:19:10 GMT 12
It did take a while to get what I was asking form my Quicksilver Silver 60s but that was not due to any reliability issues with them. They were self biasing meaning the KT66 KT88 6550 6L6 or EL34 power tubes could be dropped in without any mucking around. I always found them to be fine amps & did not miss a beat in the time I owned them. I would happily recommend them to any buyer
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Post by colinf on Aug 6, 2017 14:39:09 GMT 12
Did you have them modified to be self bias? They were fixed bias as standard.
AMR-iFi R&D
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Post by beeman on Aug 6, 2017 17:17:12 GMT 12
No they are self biasing & came from the factory that way
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Global Moderator
 Post by michaelw on Aug 6, 2017 18:13:54 GMT 12
i think they switched with the move to new output tubes after the 8417.
they recently announced a basic integrated. quicksilveraudio.com/products/integrated-amplifier/
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Post by colinf on Aug 7, 2017 9:51:41 GMT 12
Self bias is a much more reliable way to go. It just results in reduced power output.
The new integrated looks very nice, and reasonably priced too. The small 6bq5 output tube is a good sounding tube, and readily available. I guess they must be running them in class A or with self bias to get 20w with four of them a channel. AMR-iFi R&D
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Post by guitardude on Aug 7, 2017 10:16:51 GMT 12
I had to google that one. It's an EL84 ? Didn't the VTL tiny triodes run 4 of those a side for a claimed 25w ? Fairly commonly used tube back in the day, with a good reputation for sound quality.
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Post by colinf on Aug 7, 2017 11:39:42 GMT 12
6bq5/ EL84.
I had a set of VTL Tiny Triodes way back when. They sounded very sweet. Guitardude, your amp runs with self bias class A for low distortion and reliability. AMR-iFi R&D
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Post by Owen Y on Aug 7, 2017 12:10:36 GMT 12
Some say you rarely hear a bad sounding EL84 amp.
DarkLantern blog - darklanternforowen.wordpress.com
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Post by colinf on Aug 7, 2017 12:28:59 GMT 12
It's another of those high gain (for an output tube) and medium to high transconductance tubes, like the 8417 but much smaller, about 1/3 the size. It has a nice light, airy and sweet tone that is hard to emulate with other tubes IME. I think Quicksilver are on the right track in using this tube.
AMR-iFi R&D
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