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5V4 good substitute for 5U4 in an MC30?

angelaudio

angelaudio

Super Member
Was told that the 5V4 tube takes a little longer to ‘warm up’ and doesn’t send voltage ‘downstream’ as fast as the 5U4 therefore it would be ‘healthier’ for the amp and ‘prolong’ the life of internal components. A lot of quotation marks in that statement, I apologize. I’m new to tubes so my technical knowledge is severely lacking.

Any advice would be greatly appreciated. Thanks again folks!
 
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You really should compare the tube data before attempting a swap. The 5V4 doesn't drop as much voltage as the 5U4 so no, I wouldn't change it as it may make the circuit act weird as it was designed for the 5U4 tube to begin with.

http://tdsl.duncanamps.com/show.php?des=5V4G
http://tdsl.duncanamps.com/show.php?des=5U4GB

I think guitar players like to roll different rectifier tubes for different sounds but its not really a good idea in general as it changes the sound and characteristics of the amp. I think it falls in the same category as the 12AU7 - 12AX7 debate
 
century tek said:
You really should compare the tube data before attempting a swap. The 5V4 doesn't drop as much voltage as the 5U4 so no, I wouldn't change it as it may make the circuit act weird as it was designed for the 5U4 tube to begin with.

http://tdsl.duncanamps.com/show.php?des=5V4G
http://tdsl.duncanamps.com/show.php?des=5U4GB

I think guitar players like to roll different rectifier tubes for different sounds but its not really a good idea in general as it changes the sound and characteristics of the amp. I think it falls in the same category as the 12AU7 - 12AX7 debate
Click to expand...
Thanks for the input. I am not well versed in the art of tube rolling so I wouldn’t want to damage any internal components. Even if I did examine the specs I wouldn’t know exactly how it would affect the entire circuitry, but I’ll err on the side of caution on this one.
 
The GZ37 has a slow warmup time, and drops about the same voltage as a 5U4, but they've gotten pretty expensive. The 5V4, as mentioned, drops a lot less voltage so your B+ will be way too high.
 
If you are itching to roll tubes in the MC30s, try different brands of 6L6GC output tubes. Similarly, you can try European versions of the preamp tubes.
 
Several years ago I tried a range of 5V rectifiers in my stereo 300B amp and found the worst sounding was the 5V4 and the best the 5AR4 and 5AU4. Note the 5AU4 requires 3.75A of filament current!
 
The 5AU4 is a pretty uncommon rectifier. I've got a Bogen that calls for either a pair of 5AU4 or 5AR4. Its running 5AR4's simply because I can get those. Shame they aren't more available, its a pretty hefty rectifier if you can power it.
 
^^ This. There's really no need for even slower warm up. Many folks bypass it altogether and use ss rectification with a thermistor for slow warm up.
 
Palustris said:
Several years ago I tried a range of 5V rectifiers in my stereo 300B amp and found the worst sounding was the 5V4 and the best the 5AR4 and 5AU4. Note the 5AU4 requires 3.75A of filament current!
Click to expand...

I never cared much for them either until I built my Williamson amps, where they are a perfect fit and a stellar performer.
 
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