Dammit now I have to wait for my new CV378's to burn in? 
+2
deepee99
jfine
6 posters
Do rectifier tubes need to burn in too?
jfine- Posts : 152
Join date : 2017-06-19
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
At the risk of being flamed here, I don't think so. Rectifier tubes are just great big diodes. They either work or they don't, and you'll know pretty quick if they aint. They need to be appropriate to the load. A 5R4 that Kevin Deal's selling ain't the same critter as a 5AR4. You want honest rectification, this is once place where I yield to well-built s/s power supplies.jfine wrote:Dammit now I have to wait for my new CV378's to burn in?
Big Harry- Posts : 51
Join date : 2016-06-19
Location : Kingman, Arizona
Rectifier tubes do not require a burn in period to work properly. A 5R4 is not a direct replacement for a 5AR4 as the voltage drop across the 5R4 is substantially higher than the 5AR4. The only reason to do a swap is if the B+ voltage needs to be dropped.
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
I'd like to clarify my comment a bit. In low-wattage applications such as pre-amps, tube rectifiers are preferable. But in power amps, no.
For an SP-14, the Bendix 5852, which was a mil-spec 6x5, is the cat's meow. Very slow startup, which saves wear and tear on the downstream tubes. And it will out-live you.
For an SP-14, the Bendix 5852, which was a mil-spec 6x5, is the cat's meow. Very slow startup, which saves wear and tear on the downstream tubes. And it will out-live you.
jfine- Posts : 152
Join date : 2017-06-19
deepee99 wrote:
At the risk of being flamed here, I don't think so. Rectifier tubes are just great big diodes. They either work or they don't, and you'll know pretty quick if they aint. They need to be appropriate to the load. A 5R4 that Kevin Deal's selling ain't the same critter as a 5AR4. You want honest rectification, this is once place where I yield to well-built s/s power supplies.
Well, I can hear the diff straight away between this CV378 and a chinese 5AR4, so, that made me think about burn in time.
5R4? I'm not sure I follow you, what is that tube for?
I only bought from K Deal once long ago.
jfine- Posts : 152
Join date : 2017-06-19
Big Harry wrote:Rectifier tubes do not require a burn in period to work properly. A 5R4 is not a direct replacement for a 5AR4 as the voltage drop across the 5R4 is substantially higher than the 5AR4. The only reason to do a swap is if the B+ voltage needs to be dropped.
Bob says it was OK for the M125, is he wrong? (If you mean 5R4 = CV378/GZ37)
skriefal- Posts : 135
Join date : 2011-09-20
Location : Utah, USA
I'm not sure why 5R4s were mentioned here. A 5R4 has a much higher voltage drop than a CV378/GZ37. CV378/GZ37 is a much better choice for use in the M-125s.
Bob Latino- Admin
- Posts : 3262
Join date : 2008-11-26
Location : Massachusetts
jfine wrote:Bob says it was OK for the M125, is he wrong? (If you mean 5R4 = CV378/GZ37)
You can use a 5R4 rectifier in any of the VTA amps but they are not ideal for these amps and should be used only as a back-up rectifier. You can also use a 5U4 as a back-up rectifier. If you want to use a TUBE rectifier in a VTA amp a 5AR4 works fine despite what some may say. The best choice would be a Mullard GZ33 (CV5745) or GZ37 (CV378) but they are not made anymore, are getting scarce and are usually $100 USD or more if you can find them.
That said > A $23 Weber WZ68 solid state rectifier works great in these amps despite what it says on the Weber web site > "only recommended for guitar amps". The word that I got about their recommendation is that some of the VTA amp kit builders would drop in their WZ68 into a kit amp with an improperly wired high voltage system and smoke the WZ68 on their first start up. Solid state rectifiers are not as forgiving as most tube rectifiers and will usually self destruct before the amp's fuse blows.
Bob
Dogstar- Posts : 361
Join date : 2014-06-23
I was using a WZ68 Webber SS Rectifier along with KT120's and was quite happy with the sound. To me it did not seem to effect the sonic quality as all of the other tubes in the system seem to. I'm pretty sure I read that the rectifier doesn't effect the sound and maybe I've been psychologically convinced that it doesn't.
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
Dogstar wrote:I was using a WZ68 Webber SS Rectifier along with KT120's and was quite happy with the sound. To me it did not seem to effect the sonic quality as all of the other tubes in the system seem to. I'm pretty sure I read that the rectifier doesn't effect the sound and maybe I've been psychologically convinced that it doesn't.
Solid-state Webbers are consumables, just like toobs, but I couldn't tell the difference, either. You can prolong the life of a Webber significantly by drilling a few cooling holes in the copper cap. Easy job. Thanks to Troy Madden for that fix.
Dogstar- Posts : 361
Join date : 2014-06-23
I had a WZ68 in with the KT120's for almost 2 years before switching to the GL tubes for output and rectifier. The Webber was still performing just fine when I switched. I may put it back in just to test it with the current 6SN7 in the center spot on the PCB.
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