Replacement tubes for Custom Vibrolux Reverb

[mottaz]

Dunno if this is the right forum but I'll give it a shot. I have to replace the power tubes in my CVR because one is broken. What are my options for tube types? Any 6L6 or 5881? Is it true these don't have the high voltage requirements of a 6L6GC? Anybody have a fav for this amp? Any opinions on the TAD 6L6WGC-STR?

* Stock tubes are (ready?) Fender branded, Groove tubes branded(GT6L6B), Sovtek 5881WXT. These are like a NASCAR jacket. All 3 brands/types are printed on it.

* Fender site, manual, "specs" both say the amp uses "6L6" (not "6L6GC")

* tubedepot.com says this about the stock tubes - Not exactly a ringing endorsement "The Sovtek 5881WXT is one of the most widely used 6L6 variants available. It is the stock tube in Fender and Mesa amps. While not the most harmonically rich tube - it is very affordable and durable."

Also, does anyone know the specs on the amp? Voltages etc? I know you have to be careful when selecting tubes. Thanks a ton

[PRNDL]

Choosing tubes is a very subjective matter, which has become much more complicated recently. In general, there is a price-quality relationship. Many are concerned about increased failure rates in new tubes.

For instance, Fender uses Groove Tubes that are tested Sovteks. They add about $3 to the price of the tube for the testing and labeling.

Sovteks, Electro-Harmonix and JJ's have similar prices and are preferred by many. Each has their own tonal characteristics and durability. Tung Sol's are much higher quality, but are about double the price.

A careful reading of your tubedepot.com quote is very revealing. It states that most like Sovteks for durability and price. Other brands sound better but don't last, or are a lot more expensive.

Most people have trusted brands that they've come to rely on.

The best bet is to find a local tube amp tech that tests and matches tubes. Another safe option is to get tested Groove Tubes.

[MWJB]

The important thing is biasing up the tubes...your bias range resistor (if I remember correctly) is situated on the control panel PCB, making access/adjustment a pain. The Sovtek 5881 can sound OK in BF style amps, but no, they are not exactly the richest sounding tube in the world. They are rugged.

Voltage in your amp should be early/mid, 400's, so any 6L6GC/5881 will be fine at 30-35mA.

Groove Tubes are a reseller, their tubes are made by the same factories as everyone else's.

Unless the owner has a specific preference, I would simply try various matched pairs in your amp, monitoring with a bias probe, until I found a pair that idled no lower than 28mA, up to 35mA...rather than go to the trouble of pulling the control panel PCB. Measure idle current with the tremolo switched off, rather than turned down. If you have a local tech/vendor with a good supply of matched pairs you should be OK.

It is generally assumed that current production 6L6s are 6L6"GC"...even if they don't handle 30W dissipation. A 6L6 is a metal tube, "G" means glass.