Diezel Amps and Tubes

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journeyman73

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I have started exploring Diezel amps and am massively confused with what tubes they are shipping with and/or just tubes in general.

So, I was trying a VH4 and a Herbert. Both were advertised as loaded with KT77 tubes.

On the VH4 - they seem to be printed in big red letters as JJ KT77 tubes. Great....but then i noticed on the other side of the tube it is stamped in smaller gold lettering with 6L6...I thought KT77 tubes and 6l6 tubes are different - how can a tube be stamped with both??

On the Herbert - they seem to be TADs that are stamped as 6l6...not the tube I wanted but then based on the Vh4 tubes being stamped both KT77 and 6L6 is it possible these Herbert tubes, even though they don't say KT77 on them, are somehow KT77s??

I thought it would simply be KT77 loaded amp - tubes say KT77. 6L6 loaded amp - tubes say 6L6. But this dual stamping has me doubting even simple common sense??
 
This is strange. Can you provide us some photos of the tubes? I think that the label directly on the glass is the right one. The stock tubes have changed over time. For some years the JJ KT77 were stock poweramp tubes but now they have been swaped for 6L6 due to the JJ tubes shortage.
 
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Bro KV said:
Due to shortages they are installing the “next best” available tubes. My Herbert was built October of last year and came with TAD Redbase 6L6
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That’s helpful - and would explain why a lot of places would be advertising KT77 (almost like part of the model designation) and stock photos but it actually comes with 6L6s…

Any ideas why a tube would be stamped with both designations? Are tube companies just doing the same (ie ‘we don’t have KT77s so we will just sticker our 6L6 with a KT77 label’)?
 
strungout82 said:
This is strange. Can you provide us some photos of the tubes? I think that the label directly on the glass is the right one. The stock tubes have changed over time. For some years the JJ KT77 were stock poweramp tubes but now they have been swaped for 6L6 due to the JJ tubes shortage.
Click to expand...

Not the best pics…

But this is a tube loaded in the VH4 - front side has KT77 in red paint, same tube has 6L6 in gold on the back. both painted directly on the glass...



 
The 6L6 tubes in Herbert seem legit, they are the new diezel stock tubes (6L6 redbase by TAD). The tubes in VH4 look like KT77 by JJ and the 6L6 letters are probably just a serial number. My KT77 have 16K8 on their backs.
 
strungout82 said:
The 6L6 tubes in Herbert seem legit, they are the new diezel stock tubes (6L6 redbase by TAD). The tubes in VH4 look like KT77 by JJ and the 6L6 letters are probably just a serial number. My KT77 have 16K8 on their backs.
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you mean just randomly, coicidentally a stock number that specifies another tube type? what would be the odds of that! crazy lol

it's interesting though too - if the Herbert is shipping with 6L6 because of some problem with KT77 supply, why did my VH4 come with the JJ KT77s? maybe just a few months older in stock and a VH4 off the line, now, would also be coming with the TAD 6L6 like the Herbert?
 
I immediately put 6l6s out of my diezels and go 6l6 . They just are more agressive and tighter to me . But it’s cool whatever them come with .But I think thru are just putting in 77s still when they have a chance but ho with 6l6s if not
 
journeyman73 said:
you mean just randomly, coicidentally a stock number that specifies another tube type? what would be the odds of that! crazy lol

it's interesting though too - if the Herbert is shipping with 6L6 because of some problem with KT77 supply, why did my VH4 come with the JJ KT77s? maybe just a few months older in stock and a VH4 off the line, now, would also be coming with the TAD 6L6 like the Herbert?
Click to expand...
Yep, the new VH4 are shipped with 6L6 now. So your VH4 is from the older supply. Look at the thomann website, all new diezel amps are shipped with 6L6 tubes last few months. But don't be sad. The KT77 are nice tubes. I like them in my Herbert a lot. When I bought my latest VH4 I have changed the JJ KT77 for new EL34 tubes and the difference in sound was quite small. It is not worth to change the fresh KT77 for EL34.
 
strungout82 said:
Yep, the new VH4 are shipped with 6L6 now. So your VH4 is from the older supply. Look at the thomann website, all new diezel amps are shipped with 6L6 tubes last few months. But don't be sad. The KT77 are nice tubes. I like them in my Herbert a lot. When I bought my latest VH4 I have changed the JJ KT77 for new EL34 tubes and the difference in sound was quite small. It is not worth to change the fresh KT77 for EL34.
Click to expand...
yep, I would be totally happy with KT77s...

what i am a little more uncertain about is how I like the Herbert with the 'stock' 6L6s, now....not having been able to try one with KT77s I am not sure of how big a difference it would make
 
KT77 have a Little more mid's and glassy top compared to the 6L6's.
Try and find some on the used market as your looking at $200 for a sextet of KT77's
Tubedepot.com has em in stock
 
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