Found! New production rectifier tubes 5AR4 / GZ34 that are actually good and last!!!

I found some new production 5AR4 / GZ 34 tubes that are very good and hold up well.

http://www.guitarcenter.com/Groove-Tubes-Gold-Series-GT-5AR4-GZ34-Rectifier-Tube-100368364-i1125635.gc

http://www.tubesandmore.com/products/T-5AR4-STR-TAD

These are hand selected and tested for quality and durability. Try them.

Groove Tubes 5AR4's are Sovtek, and I believe TAD's are Shuguang.
I think you might be getting a little more for your money by buying "hand selected", but probably not much. At least it should be guaranteed to work right out of the box, maybe. The same guts are in there as every other one, how could durability be guaranteed to be better?
In my ST-70 I ran a plain jane $13 Sovtek for a year before it went south.
If you really want your rectifier to last, do the the "yellow sheet" mod.

Blitzen wrote:Groove Tubes 5AR4's are Sovtek, and I believe TAD's are Shuguang.
I think you might be getting a little more for your money by buying "hand selected", but probably not much. At least it should be guaranteed to work right out of the box, maybe. The same guts are in there as every other one, how could durability be guaranteed to be better?
In my ST-70 I ran a plain jane $13 Sovtek for a year before it went south.
If you really want your rectifier to last, do the the "yellow sheet" mod.

What's the "yellow sheet mod"?

P.S. The TAD's look like svetlana's. The color of the base suggests this.

These tubes are guarenteed for 90 days!

Blitzen wrote:Groove Tubes 5AR4's are Sovtek, and I believe TAD's are Shuguang.

That is correct. The TADs are Chinese, Svetlana does not make a 5AR4.

Bob Latino has posted the mod here: Diode mod for 5AR4s

Jim McShane wrote:

Blitzen wrote:Groove Tubes 5AR4's are Sovtek, and I believe TAD's are Shuguang.

That is correct. The TADs are Chinese, Svetlana does not make a 5AR4.

Bob Latino has posted the mod here: Diode mod for 5AR4s

Awesome, Thanks!!!

Jim McShane wrote:

Blitzen wrote:Groove Tubes 5AR4's are Sovtek, and I believe TAD's are Shuguang.

That is correct. The TADs are Chinese, Svetlana does not make a 5AR4.

Bob Latino has posted the mod here: Diode mod for 5AR4s

I ran the weber copper cap rect. and it failed after 6 hours and caused an output tube to short, and blew the 5 amp slo-blo fuse.
I've been running the "Groove tubes" 5AR4 for 11 hours at high levels and no problems. Bias voltage is stable after 11 hours. The only issue is a real hot power transformer.
I thought about developing an attachable extruded aluminum heat sink to the power transformer. The problem with this would be a metallurgy issue. Aluminum and steel don't mix too well.

Re: > "The only issue is a real hot power transformer."

The power transformer on the VTA ST-120 will run pretty warm - BUT - there is no danger to the power transformer. I have done many "amp heat related" tests here and the heat from the transformers on these amps is "the nature of the breed". Read an earlier forum post from May of 2011 on a heat test of the Tung-Sol KT120's on a VTA ST-120 amp.

Heat test post on a VTA ST-120 amp with Tung-Sol KT120 output tubes

Bob

Analog Man wrote:

Jim McShane wrote:

Blitzen wrote:Groove Tubes 5AR4's are Sovtek, and I believe TAD's are Shuguang.

That is correct. The TADs are Chinese, Svetlana does not make a 5AR4.

Bob Latino has posted the mod here: Diode mod for 5AR4s

I ran the weber copper cap rect. and it failed after 6 hours and caused an output tube to short, and blew the 5 amp slo-blo fuse.
I've been running the "Groove tubes" 5AR4 for 11 hours at high levels and no problems. Bias voltage is stable after 11 hours. The only issue is a real hot power transformer.
I thought about developing an attachable extruded aluminum heat sink to the power transformer. The problem with this would be a metallurgy issue. Aluminum and steel don't mix too well.

I find it hard to believe that a faulty rectifier could cause an output tube to short. The opposite is
more likely ( that a flashing output tube may kill the rectifier AND the fuse)

I am very happy with a new production Sovtek, which is in service for 8 months now. The original Chinese one that came with the ST70 kit was gone after two weeks.