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Inspire by Dennis Had Enjoying Vacuum Tube Audio

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  #5291  
Old 05-07-2019, 10:05 AM
maro maro is offline
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Quote:
Originally Posted by nhparrot View Post
What are folks using as a rectifier with the 6F6 metal tubes? What does Dennis recommend?

Thanks
Glenn
I have RCA 6F6G and 6F6M and use a 5U4G rectifier with the tubes. Also have used a 5Y3GT which produces a warmer sound. Prefer the 5U4G punch and bass control.
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  #5292  
Old 05-07-2019, 03:33 PM
Miami Ed Miami Ed is offline
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I also use a 5U4G with the 6F6. Dennis recommends this combination.

The best output tubes I have heard in my Firebottle. Surprising bass.
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  #5293  
Old 05-08-2019, 12:27 PM
Cdrdel Cdrdel is offline
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Default rectifier tubes

I haven't tried the 5U4 rectifier with the RCA 6F6 metal cans. Will give it a try. I have been running 5AR4 in my Triode SET with IIps. Probably running the 6F6's too hard with the 5AR4 - it does sound nice though with this combination.
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  #5294  
Old 05-08-2019, 03:59 PM
Comzee Comzee is offline
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It confuses me to use a 5u4 with lower power tubes, since 5u4 tubes are 3amp, and 5r4 tubes are 2amp. I guess the 2amp rectifiers have higher voltage output tho?
Found this chart online.
Maybe somebody that knows more can shed some light onto this.
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  #5295  
Old 05-09-2019, 08:23 AM
FloridaBoy FloridaBoy is offline
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Quote:
Originally Posted by Cdrdel View Post
I haven't tried the 5U4 rectifier with the RCA 6F6 metal cans. Will give it a try. I have been running 5AR4 in my Triode SET with IIps. Probably running the 6F6's too hard with the 5AR4 - it does sound nice though with this combination.
If, in a darkened room after the amp has warmed up, the tubes are not red plating all should be well.
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  #5296  
Old 05-09-2019, 02:41 PM
Miami Ed Miami Ed is offline
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Quote:
Originally Posted by FloridaBoy View Post
If, in a darkened room after the amp has warmed up, the tubes are not red plating all should be well.
True, except in this case where we are using metal tubes.
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  #5297  
Old 05-09-2019, 07:53 PM
oldtech0 oldtech0 is offline
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Quote:
Originally Posted by Comzee View Post
It confuses me to use a 5u4 with lower power tubes, since 5u4 tubes are 3amp, and 5r4 tubes are 2amp. I guess the 2amp rectifiers have higher voltage output tho?
Found this chart online.
Maybe somebody that knows more can shed some light onto this.
The higher the rectifier tube voltage drop, the lower the B+. 6F6 is rated for around 375 VDC plate and 285 VDC screen. Using a rectifier with a high voltage drop can get one in that range. A regulated screen voltage at around 250 is also good for tube life. I run a 5R4GY or 5Y3GT with the 6F6 in my Firebottle.
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  #5298  
Old 05-11-2019, 04:13 PM
pechelman pechelman is offline
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for those with one of Dennis' amps with the B+/AC switch on the front, are you all leaving the amp powered up with B+ voltage to keep the heaters on or do you cut all power with the rear switch? I thought I read Dennis recommends just leaving it with B+ on 24/7.

Is it normal to hear speaker hum with B+ only?
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  #5299  
Old 05-12-2019, 12:32 PM
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straitwire straitwire is offline
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Hey pechelman, with the B+ off there is some magnetic field pick up from the power transformer.
With the B+ in the on position with the amp operating, DC current is flowing through the output transformers and the hum will be eliminated.
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  #5300  
Old 05-12-2019, 12:48 PM
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straitwire straitwire is offline
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I should add this as well...
The B+ switch on and off is provided to allow filament warm up of New old stock or used 45 tubes from many years ago.
This allows filament conditioning of 45 tubes that may be up to 70 years old, (without applying B+), this allows the tube to come to life slowly.
Of course with new production 45 tubes it is not be necessary to have the B+ switch.
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