Cole Posted January 20, 2009 Share Posted January 20, 2009 In my marshall modded head i have been using a tung-sol 12ax7 in the preamp. I've been searchin around here and sewatt to find a solution to the slightly frizzy top end. I then decided while my fendery combo is on the worktable why not try the Jan phillips 5751 in my marshally head. BINGO problem solved! It sounds amazing. My fendery combo had a wierd hum. Its kind of a howling noise that gets louder if you barely hit the pots or switches. Now my head is making this noise so im thinkin it is the tube. I took out the tube to look at it. The 12ax7's pins are shiny and silver but the 5751's pins are blackish gray. Should i pitch this tube? or would just cleaning it work, and what would i clean it with? Link to comment Share on other sites More sharing options...
TWANG Posted January 20, 2009 Share Posted January 20, 2009 you can try cleaning it. just don't be harsh. I use a thin diamond fingernail file.. since it's light and cuts light or medium.. and just try to get all the way around each pin. subtle pressure, more strokes. tWANG Link to comment Share on other sites More sharing options...
Eracer_Team Posted January 21, 2009 Share Posted January 21, 2009 is you Jan Phillips a New Old Stock tube or a new tube? Link to comment Share on other sites More sharing options...
Cole Posted January 21, 2009 Author Share Posted January 21, 2009 I have no idea, ijust know its a Jan Phillips. I bought it about 4-5 months ago, and the writing on it is green. Im thinkin it was about 10-15 bucks so if that tells you anything about it. Thanks twang i'll try that method of cleaning it. What do you think could have caused this? Link to comment Share on other sites More sharing options...
MikeRom Posted January 21, 2009 Share Posted January 21, 2009 Sounds like you just stumble on the cause of your humming problem. To make sure that was actually the cause you could take the tube you pulled from the Marshall and put it in the Fender to see if the problem truely is gone. Link to comment Share on other sites More sharing options...
Eracer_Team Posted January 21, 2009 Share Posted January 21, 2009 okay time to re-read what you wrote.. So you have a VJ-Head with the 'marshall' mod's that had tung-sol with a frizzy sound you also had a VJ-combo with 'fendery' mod's that had a hum and a jan-philips putting the jan in the head got rid of the frizz and sound great but it now has the hum of the combo... so the hum followed the jan-philips does the combo frizz with the tung-sol in it? Watch out for the marshallized head's they have a tendancy to jumper R6 and pull r7 for the most gain which can cause too much gain going into your el84; possible cause for the frizz sound (the tung 12ax7 has the most gain the jan being a 5771 would have less gain). so it sounds like you had 2 bad pre-amp tubes... time to visit the tube store. might as well buy 2 sets of tubes for each amp as spares. Link to comment Share on other sites More sharing options...
m-theory Posted January 21, 2009 Share Posted January 21, 2009 If the hum goes away with a different preamp tube, you've got a bad tube, obviously. Why did this happen? Because, the tube is a manmade item, and therefore will eventually fail. JAN Phillips are all NOS (or used). There is no such thing as a new production JAN Phillips. Phillips made these for the military, thus the "Joint Army Navy" moniker. Link to comment Share on other sites More sharing options...
lostindesert Posted January 21, 2009 Share Posted January 21, 2009 Some good pre-amp tubes are: EH/Electro-Harmonix 12AX7, JJ/tesla ECC83/12AX7 and the Sovtek12AX7LPS, all present day manufactured tubes. Peter Link to comment Share on other sites More sharing options...
Cole Posted January 21, 2009 Author Share Posted January 21, 2009 Yes, the hum followed the Jan phillips so im gonna get a replacement for that. The frizzyness didn't follow the tung-sol so i think it was just too much gain on the head but the 5751 smoothed it out nicely but now is humming. On the head i have R6 at 100k and R7 on a switch with 100k/1meg and i very seldom use the 1 meg so it doesn't have a ton of gain but sounds MUCH better with the 5751. I'll have to order one for each of my amps and get a replacement. And if im hearin you right m-theory my Jan phillips was used when i bought it? Whats a different good brand of 5751? Thanks! Link to comment Share on other sites More sharing options...
Eracer_Team Posted January 21, 2009 Share Posted January 21, 2009 lots of info here: http://thetubestore.com/gainfactor.html Link to comment Share on other sites More sharing options...
cGil Posted January 22, 2009 Share Posted January 22, 2009 Buy yourself some fresh JAN Phillips 5751's from TheTubeStore and savor the good tones. I'm pretty sure TheTubeStore still has the best price going for a 5-pack. I've got couple of old and very rare, gold pin Sylvania GB-5751's in my identical twins (modded VJr amps). Good luck finding those tubes. The went extinct years ago. But I recently bought a few JAN Phillips 5751's. I tried 'em out, but they sounded exactly like the Sylvania's, so the JAN Phillips went back in the box for future reference. Point was, those same two Sylvania's have been in constant use for something like 10 years old now, and they're still sounding good as new! But I know they aren't immortal and they won't last forever. Fortunately, now I'm ready. I have a stash! Oddly, the modern production Sovtek 5751 sells for the same price as the NOS JAN Phillips tubes, but I'll bet they have the same short lifespan that all modern tubes (especially Sovtek) seem to suffer. Thanks to the EPA and RohS, and God knows what new regulatory agency will step in next, it's now become impossible to make tubes with the quality of metal they had access to in the 60's. NOS tubes simply live a lot longer than modern production tubes. Especially when it comes to preamp tubes. Gil... Link to comment Share on other sites More sharing options...
Eracer_Team Posted January 22, 2009 Share Posted January 22, 2009 Thanks to the EPA and RohS' date=' and God knows what new regulatory agency will step in next,[/quote'] Yet they can put mercury into those energy efficient curly light bulbs that they are trying to push us into buying before 2012. You can’t put them in the garbage and if you drop and break one in your home you have to have your home decontaminated. Link to comment Share on other sites More sharing options...
m-theory Posted January 22, 2009 Share Posted January 22, 2009 And if im hearin you right m-theory my Jan phillips was used when i bought it? not necessarily. It could've been NOS. It just couldn't be new production, since they don't make them anymore. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.