JAN Philips 6L6WGB in Mark IV?

[boola]

Hi,

This website says that the JAN 6L6WGB can be used in any amp that uses 6L6GCs

http://thetubestore.com/jan6l.html

Will they work ok in the Mark IV? I know that they need to be in the corect transconductance range, are they?

Thanks

 

[212Mavguy]

Better to not attempt this one. An identical question appears on the second page of this section of the forum. Pay particular attention to Stokes' post, he is an amp tech.

 

[boola]

hmmm but I've looked at the data sheet and the rated voltage for 6L6WGB is 400V, not what Stokes said.... A Normal spec 6L6 is ~370 which is what the Mark IV runs at.

These military (JAN) versions can handle even higher than 400V according to that website.

So I'm confused as usual!

 

[trem]

Mark IV runs at 460-470V.

FWIW I had a pair on my old Pro Reverb, and it lasted two years. But judging from Stokes's post, I think I got lucky more than anything.
http://forum.grailtone.com/viewtopic.php?t=26201&highlight=6l6wgb

 

[stokes]

hmmm but I've looked at the data sheet and the rated voltage for 6L6WGB is 400V, not what Stokes said.... A Normal spec 6L6 is ~370 which is what the Mark IV runs at.

These military (JAN) versions can handle even higher than 400V according to that website.

So I'm confused as usual!

Those tubes may very well hold up,but they may not.The tubestore is in the business of selling tubes,if they tell you they wont work in your amp they wont sell as many.If the tube is identical to the internal structure of the 7581A,why wont you get the identical 35 watts?Because they arent identical.A 7581A is rated for 500v's.The size of the glass makes no difference,RCA or GE (one of them,I dont recall offhand),I have a pair downstairs,makes a short bottle 7581A that gets 35watts.Like I said,they may be okay,but they are not rated for the voltage your amp puts on them.If you want to take the chance, its your amp.Keep in mind that unless the tubestore can match them for your Boogie like Mesa or GT does,you will have to check and re-bias these tubes.Many of these military tubes are tough and can possibly take the over taxing...but many wont.It aint worth the chance.

 

[boola]

Ok thanks, finding out the plate voltage of the Mark IV is ~460v means I wont be using these!

 

[boola]

Well errr I have now got JAN Philips 6l6GBs in my Mark IV!

The reason is that I spoke to Derrek at watford valves about them. I was enquiring if he had some GCs but he said he preferred the tone of the GBs which were probably his favourite 6L6 of all time.

I said I was worried about plate voltages to which he replied that he used to run these things in his mark IV and now he has 12 or these in his 400+ !!!- bass is obviously an expensive instrument. He said that he's had them in there for the best part of 10 years without a problem though.

I had been offered a nos quad real cheap - Derrek advised me not to buy his GCs but to get these GBs from someone else, so I did!

The GBs are certainly a great sounding tube. Anyone who's tried nos power tubes will know how they are smoother and have a 'quality' to them, these are the same.

They haven't got as low a bottom end thuimp as the =C= GCs I have but there's still lot's of bass. They have a fenderish midrange twang to them which comes through on clean and gives R2 quite a vintage sound. In lead at full grind they are great with a fat midrange and bass with good cut harmonics without being at all harsh.

They've been in the amp for about 2 months now, fingers crossed!