TUBE QUESTIONS

[Annah]

I've recently noticed a substantial drop in output level on my Marshall TSL100. From info I've gathered on the 'net it would most likely be my 12AX7 (ECC83) pre-amp tubes starting to fade away. Initially, I assumed it would be the EL34 power tubes going, but I learned that there are only two states for those tubes: alive or dead. So that rules them out as possible culprits.

It has been my intention to get a backup set of tubes soon anyway, but now it looks as if I need to go ahead and replace the 12AX7s, so my question is this: Any of you guys have first-hand experience changing pre-amp tubes in a Marshall head? And if so, what did you replace and what did you replace them with? Any noteable differences in tubes?

My main tonal desires are to maintain warm clean tones and having a sweet, searing lead and heavy crunch sound.

I'm thinking I'll probably just have to experiment with different brands of tubes, but that's surely not cheap, so I'm hoping you can enlighten me.

Thanks!

Annah

Annah's Lair

[JacksonShredder]

Re: TUBE QUESTIONS

Hey Annah

It most likley is the Power Tubes

what you can do is take out the out side tubes
tube 1 and 4 and run it at 50 watts if the problem stops then the pair you took out is bad if the problem still happen then take the tubes that are still in the amp out and exchange them with the first one you took out
most of the time not all for tubes go out at once so that should work

that is how come i have a 50 watter only 2 power tubes [img]images/icons/grin.gif[/img] [img]images/icons/tongue.gif[/img]

[OklaStrat]

Re: TUBE QUESTIONS

power tubes tend to wear pretty evenly... when one goes, it's usually time to change all 4.

If you decide to run the inside or outside pair for a bit, DO NOT forget to change your impedence selector to one step down - if you are running into a 16 ohm cab, set the amp to 8. an 8 ohm cam, set it to 4, a 4 ohm cab, don't do it [img]images/icons/grin.gif[/img]

Pete

[Soloist1]

Re: TUBE QUESTIONS

Ya know I just typed this big long post and the friggin firewall wiped it out. Son of a *****. Anyhow I think I recall you said you are a huge Floyd fan Annah. If that's the case I would highly recommend a Mullard for your lead channels socket. It has the ability to get even higher gain than Floyd like tones as well. I am currently using one in the 3rd channel of my preamp which is my favorite. It has a sweet mid range tone but is not lacking in the chug or lead departments what so ever. It sings is the best way to describe it.

[Soloist1]

Re: TUBE QUESTIONS

I'll do this in a two parter to avoid another firewall failure. John here is the list bro.

Initial: RCA 7025, Extremely bright and super high gain.
Clean: RCA 5751 Black Plate, cleans up the cleans but is still nice and shimmering.
OD Channel 2: Telefunken smooth plate ECC83. This tube was bred in hell. It will rip your face off and stump your skull. Very bright and tight. The lead tone screams like a biatch.
OD Channel 3: Mullard ribbed plate for her pleasure ECC83. Check review above.
Tone: RCA 12ax7a, perfect balance of all high gain tubes in my opinion.
Sec. EQ: RCA black plate 12ax7, about the same as above with a little something extra. Can't put my finger on what though.
Output: RCA 12ax7a, for the same reason as the tone socket.

All RCA's are very high in gain in my opinion. Even the 5751 has all it needs. It just seems a bit less noisy than the others.

[charvelguy]

Re: TUBE QUESTIONS

I believe your plate voltage chages quite a bit when you remove two inside tubes on a hundred watter.. you don't want to run it this way for long w/o a proper rebias.

Tom

[OklaStrat]

Re: TUBE QUESTIONS

It'll go up a little bit, but as long as she's not on the high edge of bias, it'll be ok - just may not sound the best. For a real life example, look at the boogie dual rectos - they have a spongy switch, that changes the voltage by a lot more than pulling two tubes ever will. The bias isn't altered by mesa with the spongy switch engaged - it's the same amount no matter what. There is a range that a tube will work properly in - and it's pretty wide. However, that doesn't mean it sounds the best either. My single recto is biased WAAAAYYYY cold from Boogie... but it still works. Just doesn't sound as good as it could.

Pete

[ December 03, 2002, 03:34 PM: Message edited by: OklaStrat ]

[Spiderman]

Re: TUBE QUESTIONS

Here ya' go John.

Socket 1 - 7025 USA 900/800
Socket 3 - USA 12ax7 1000/1000
Socket 4 - RCA Blackplate 12ax7 1000/1000
Socket 5 - Telefunken 800/900
Socket 6 - Mullard 900/900
Socket 7 - RCA ECC83 900/1000

Chris gives an accurate description of the tubes in his post above.

[ December 03, 2002, 05:53 PM: Message edited by: Spiderman ]

[Cleveland Metal]

Re: TUBE QUESTIONS

Chris, Dave, Thank you. I sorta had that info in some emails from you in a roundabout fashion...

I still wanted exactly what and where... Just what I needed...

Now for some prices Pete [img]images/icons/smile.gif[/img]

Thanks guys [img]images/icons/smile.gif[/img]

[Spiderman]

Re: TUBE QUESTIONS

Anytime! I think you'll be pleasantly surprised at the difference some good quality tested tubes will make.

[OklaStrat]

Re: TUBE QUESTIONS

Cleve - I'll email ya later tonight with what I have. Getting a new amp has taken it's toll on my stock [img]images/icons/grin.gif[/img]

Pete

[JACKSONFREAK]

Re: TUBE QUESTIONS

Annah typically if your preamp tubes are going you'll get distortion when on the clean channel and the distortion will sound week and fuzzy instead of smooth like it should. When the power tubes go you lose volume and tone. Less bottom end and the high end can sound crackly. But usually if you're amps power is dropping then it's most likely a power tube problem. As Pete and others have stated. ( ijust had to get in on this for fun and to make it redundant cus thats what i do) [img]images/icons/smile.gif[/img] Anyway pull the two outer tubes and see if it has its normal power level. (obviously it wont be as loud as it should be cus its running at half power). But the level should be better; if not switch the power tubed for the others you pulled out and see what it does. If it's still week most likely all four are week or leeking but you should replace all four at once anyway. If you decide on something like GT tubes
then the lower the number the more gain you get out of the output section. (wow this got longer than intended). I'll stop now. [img]images/icons/smile.gif[/img]
Promise.
Gil

[OklaStrat]

Re: TUBE QUESTIONS

Power tubes wear out slowly, like tires on a car. Whoever told you they go out 'all at once' is wrong-o. Usually you lose volume and punch when they go out.

I'd change my power tubes out first, and also the driver tube - it's the 12ax7 closest to the power tubes, and should be changed when you do the power tubes.

A friend of mine has a 100 watt TSL that he stocked with JJs - his amp sounds great. I'd probably recommend those as a new tube replacement. You can get them from Bob at Eurotubes, and also specify if you want high gain ones... (www.eurotubes.com)

if you have any more tubage questions, email me at [email protected]. I also have a few USA Telefunken and Mullards that I'd make you a deal on if you were so inclined. My tube clients (heheheh) include Spiderman and Soloist1 - we got a little more toneage from their CAE rigs.

Pete

[Cleveland Metal]

Re: TUBE QUESTIONS

Pete, if you get a chance, send me a list of what those guys bought and are actually using in the CAE and the prices, so I can start getting it together to snag some...

Thanx!!!!
-john

[email protected]

[Annah]

Re: TUBE QUESTIONS

Dang! You guys really know tubes! Thanks for the help (thus far). It's been very enlightening.

I initially figured that my problem was with the power tubes. I'm not quite sure why it was written (wherever that was) that it would be the result of failing pre's. Sheesh.

Soloist1, what kind of amp are you using? Your posts make me wonder this: Do all three of my TSL's channels run through the 12AX7's or are those primarily for crunch and lead gain? And/or are the tubes dedicated to each channel? I suppose I could find a schematic somewhere, but I'm sure it would just baffle me. I can twist knobs and plug things in (no puns intended, [img]graemlins/laugh.gif[/img] [img]images/icons/rolleyes.gif[/img] ) but I don't do schematics! HAH! [img]images/icons/tongue.gif[/img]

Hmmmm... Mullards... is that a duck? No wait, that's a Mallard..... Okay... I'm gettin' the idea here....

As far as pulling two tubes out and all that, I think I'll just get a full set of four and swap all of them out. If it sounds better, I'll just leave them in, if not, I'll put the oldies back, keep the newbies as backups and then try the same thing with the pre's just for fun. Gads... I really need to sell my Mackie so I can do this! (see my ad in classifieds)

Oh yeah, one other question... about handling... you know how you are not supposed to handle halogen bulbs with your bare fingers because the oils from your skin can cause the bulb to fry? Does that rule apply to tubes as well?

Thanks again! You guys REALLY do rock!

Annah
Annah's Lair