MarkBass LM Tube 800

[Jazz P Bass]

MarkBass LM Tube 800 is a very interesting amp.
SMPS/ Class D output section.



My thoughts are: where did they get a supply of miniature Jan 6205 tubes?

This amp has a tube in it that is clearly marked Jan 6205 Made in USA.

Not too sure (marketing?) why they even bothered.
The difference between SS (opamp) & tube is very, very subtle.
It's more of a 'feel' thing than an actual 'sound' thing.

Sans the tube portion, this documentation is pretty close (the component numbers are not close)
Mark-Bass_little-mark-iii_sm.pdf

[52 Bill]

I know a few years back somebody was selling them on eBay. He had cases of them bought from the US Government when they dumped all of the military surplus stuff.

There were a bunch of guys designing distortion pedals with them. I'm surprised that a company would actually use them in a modern product. Maybe they bought a few cases of them and sorted out the best of the lot.

[nsubulysses]

Maybe the deal was too good to pass on the tubes and doesn't matter much if you need to replace them because the amp will be obsolete anyway. This one won't exist in 40 years. Once it breaks 1 or 2 or 3 times after it's 5-20 years old it will be tossed.

[Jazz P Bass]

Here is a screen shot of full on SS & full tube.





You can see how the lower sine wave of the tube is rounded.

[J M Fahey]

Thanks for testing and posting screenshots

So the tube is being driven hard enough that it approaches saturation point .... good.