kendrick 2112 (tweed deluxe) output transformer

[shoegazed]

i had a couple of questions for you, first, the output transformer in my 2112 (kendrick tweed deluxe) just went up in smoke. of course it was sounding really great up until the smells came wafting out of it.
i was switching around some tubes, checking out how they sounded before it smoked. i guess i've always used a 5ar4 for a rectifier, and was using either some old rca 6v6's, or some sovtek 6v6's. but no smoke until i put in some electro harmonix 6v6's.

so i'm wondering if you could recommend some tubes for me, in the not too pricey range. i've heard a lot of good things about the JJ 6v6's, and am curious about using a 5y3 or 5u4 rectifier tube instead of the 5ar4.

how does the voltage get affected between these three rectifiers? and could that rectifier/output tube combo have caused the output transformer to go?


thanks SO much for your time.

andy

[MWJB]

Not knowing the spec on the Kendrick PT I can't recommend a 5U4, it draws 3A, the other rectos are 2A. 5V4GT (also 2A) is a common sub for 5Y3s in tweed Deluxes.

Using a stiffer rectifier (5V4GT/5AR4) pushes up the plate dissipation of the tubes, even with a 5AR4 I am surprised that the OT went south - you are sure that this is the case? No dodgy speaker connections? It is possible that the 5AR4 pushed things over the edge, what does Gerald say about using one in the 2112?

The JJ6V6s are pretty bullet proof.

[Bruce / Mission Amps]

Wow a GZ34/5AR4 in a tweed Deluxe? Pretty stiff for super hot running power tubes found in a 5E3.
I would say this was a mistake for not checking the power tubes first... not really the actual EH tubes.
Without knowing how much idle current they were drawing when you stuck them in, I'm thinking you probably exceeded the DC current rating of the OT and then while rockin' out exceeded the total wattage rating.
Call and ask them what the ratings are...
The Lenco made, MOJO 768 is a good replacement

[shoegazed]

wow.
i've used a ruby 5ar4 in there for about 8 years, and nothing has ever gone wrong with it. i worked at kendrick when i built this and i don't remember anything weird about the 5ar4 being used, but it has been 6-7 years ago.

the OT started smoking after a few tube swaps one of them being a nos 5ar4, so maybe it had a bit more gusto than the old ruby.

i'm not sure of the specs on the transformers other than the model numbers which are just TD2112 P for the power, and the 2112A for output.

and the speaker connections were just fine.

[Bruce / Mission Amps]

wow.
i've used a ruby 5ar4 in there for about 8 years, and nothing has ever gone wrong with it. i worked at kendrick when i built this and i don't remember anything weird about the 5ar4 being used, but it has been 6-7 years ago.

the OT started smoking after a few tube swaps one of them being a nos 5ar4, so maybe it had a bit more gusto than the old ruby.

i'm not sure of the specs on the transformers other than the model numbers which are just TD2112 P for the power, and the 2112A for output.

and the speaker connections were just fine.

Well, I don't know what the specs of the PT are.
What is the actual measured AC voltage out of the PT secondary in this PT.
You might have just had a bad 6V6 that when shorted out, pulled massive amounts of current through the OT.
Most 5E3 amps will have their power tubes idling at around 10-12 watts each.
And that will be with a NOS 5Y3GT, which has about a 25vdc-35vdc additional drop across it that a GZ34/5AR4 does not.
With a real stiff GZ34/5AR4, you could VERY easily under bias the power tubes, causing excessive current with it's associated wear and tear... plus force the OT to handle much more DC current then it was designed for... all at the same time you are Rockin' the house with 15-18 watts of AC through the OT!
You can use a GZ34/5AR4 if you rebias the power tubes to a safer idle current level.
It might take a 360ohm to 390ohm 5 watt biasing resistor to get that.