Vintage Modern praise and JJ KT66s

[surfnorthwest]

Recently I made a statement that the JJ KT66s were not real KT66 tubes. My information came frim my amp tech but apperently this is not true. Since Bob at EuroTubes is sort of the JJ Guru I decided to research what he was saying aboht them and came across this interesting article by him. Not sure I agree with all of it but a good read about the VM.

The best new Marshall?

I get asked this question all the time and for me personally it's the Vintage Modern. This amp has more of the classic Marshall sound than any other Marshall going clear back to Silver Jubilee's and then the 1975 thru 1979 Mark II amps.

The VM has a great sound right out of the box and although it's really just a single channel amp with a boost it can cover a lot of ground. It has a fat tone that is thick and complex with a great snarl in the boost mode. You can read a few reviews on the these amp over in our customer review section.

When you replace the stock power tubes with the JJ KT66's which are real KT66's the harmonic complexity increases and and the slight mushiness the amp exhibits with the stock tubes turns into a warm powerful sound. We often use a real hot high gain ECC83S in the V2 position to get a bit more form the boost.

The VM has internal bias test points but thankfully someone at Marshall talked some sense into the designers and they are using a single bias pot like the Marshall's of yesteryear. The left test point measures the left tube or pair of tubes in a 100 watter, and the right test point measures the right tube or right pair. There is a little disparity or error even with a dead on pair of tubes but it's only about 3mV.

The only hitch with the VM is that Marshall chose to use the crummy Bear trap style tube retainers... The bases on the JJ KT66’s do not fit inside the factory Bear trap style tube retainers. In Fact the retainers barely catch the rounded bases of the chinese KT66’s and do not really hold them from pulling out. So to run the JJ KT66’s or the sovtek KT66’s or the sovtek tungsol KT66’s you either have to clip the retainers off or flatten them out. While it's not an issue to run a head with no tube retainers I would not run the combo version of the VM with no retainers.

So for VM combo's we recommend removing the Bear trap retainers and replacing them with the spring and cap style retainers that hold the tube in from the top rather than the base. This is a pretty easy thing to do and can be done by removing one of the screws and then swing the stock retainer out of the way and screw in the first side of the spring retainer. Then you can remove the second screw along with the stock retainer and then screw in the second half of the spring retainer. Its well worth it because the JJ KT66's will really make a big difference.

While the VM is my pick I must also say that players looking for more versatility should give the JVM a look. I personally think it's a step up from the 2000 series Marshall's in tone quality. So if four channels along with lots of "bells and whistles" are attractive to you I would give it a listen.

[SteveD]

JJ KT66s are indeed real. When first installed they sound good but during development I found they didn't hold their tone for long when undergoing endurance tests, (the Shuaguangs did).

I suspect JJ's KT66s are aimed at the hifi market primarily, where they receive very little abuse!

The latest revision of the Vintage Modern has dual bias trims at the behest of our chief test engineer. This doesn't have a negative impact as far as I'm concerned and the original single trimmer was simply to reflect the traditional bias topology.

[surfnorthwest]

Thanks for the clairification, I won't put JJs in any if my amps, just my thing. Thought that article would give you a chuckle. In the end I have had good luck with Valve Art and Penta tubes.