Is the Tung-Sol 7027 closest to the old originals?

[jacobarber]

This feels like splitting hairs, but I'm curious. I just recently finished rebuilding my Ampeg V4 and am running my old JJ 6L6GCs because they're plenty healthy and bias is dead on.

But I saw that Tung-Sol is reproducing 7027s and claim the proper 35w plate dissipation vs JJ's 30w for their 7027s, which are just repackaged 6L6GCs with pins 1 & 6 back where they belong.

I'm not really turning this amp up to ear splitting levels, but I certainly am curious about getting it to its best original performance possible with all these shiny new components inside. Are these Tung-Sol tubes better in some way? More robust, etc.?

[Willabe]

I'd be more worried about the max plate and screen dcv. The old Ampeg V4/V22's ran the 7027a's at ~540dcv on the plates and ~530dcv on the screens. Shows ~590dcv on the plates in standby. 

The old 7027a tubes had higher max dcv ratings than the new tubes. And Electro Harmonix doesn't list the max plate/screen on their web site. JJ does.

Also, the old RCA 7027a tubes had a different pin out than 6L6GC's. The screen and grid 1 are both connected too 2 pins each. Ken Fischer said it was supposedly to get a little more heat dissipation from out of the tube so they could get the extra 5w's out of it. And the bottom RCA spec sheet says the extra pin outs are for wiring options and better heat management. Some 7027a's, like some 6550's, had metal basses for better heat control too.
 
Ampeg said on the schematics using 6550's would improve performance. But the GE 6550a spec shows only a max of 440dcv for the screen. 

And TAD has a 7027a High Performance tube, showing 600dcv plate and 500dcv screen, but only 30w dissipation.

[jacobarber]

The 6550 recommendation is for the later V4 distortion model. I don't know that they'd work in the earlier models like mine.

Another curious note is that there are 7581A reissues as well, which are simply ruggedized 6L6GCs.

I'm definitely splitting hairs here. I may try the Tung-Sol 7027As someday, but for now I'm going to just enjoy the amp for what it is. I may install an adjustable bias to dial things in easier.

[Balticnoiseforge]

Tung sol 7027a is same as their 6L6GC also but with different pinout, i would not worry to much about the JJ tubes.

Voltage is high in Ampegs but ive had JJ i a VT40 for years without any issue, same with a V4 - they havent died yet.
It is guitar amps after all, many old designs work outside the tubes datasheets maximum voltages.

Simply keep their bias low as they were from factory.