What tubes to use for more clean headroom?

[dgc480]

Hey I just bought new tubes for my amp and the cleans are breaking up too early for my tastes (around 3-4). The amp (Carvin MTS3200) was running 4 sovtec 5881s and 5 sovtec 12ax7s. Now it's running 5 Ruby Tubes 12ax7ac7 and 4 Svetlana winged c (SED) 6L6GC. I can't figure out whether power tubes or preamp tubes are responsible for early clean breakup. I just don't know if I need to replace the power tubes or the preamp tubes, or both, in order to get more clean headroom. Any comments on which 6L6s and which 12Ax7s have better clean headroom, and yet retain high gain on the distortion?

Thanks guys,

Dylan Cobb

[the_bleeding]

preamp tubes are

 

put a jan 5751 in v1.

[guitarbilly74]

 

preamp tubes are put a jan 5751 in v1.

 

 

and a 12AT7 in the PI (on that amp it's V5 I think)

[Reauchambeau]

6550 output tubes have more headroom.

[the_bleeding]

 

and a 12AT7 in the PI (on that amp it's V5 I think)

 

 

if at7's are too big of a jump (which most people find they are) you can use a 5751, or a 12au7.

[dgc480]

thanks guys. So I'm wondering why I need a 5751 or a 12at7 now when I used to have plenty of clean headroom with the sovtek 12ax7s across the board? I read something about 6L6GC having clean breakup...do you think 6L6GC has more clean breakup than 5881s? Are the svetlana winged c 6L6GCs known to have lots of clean breakup? Thanks

[BornUnderBadSgn]

http://www.300guitars.com/articles/preamp-tube-gain-factors-and-substitution-chart/

 

The chart might be of some assistance.

[dgc480]

Yea it does thanks. I guess I just don't want to replace a 12Ax7 with a lower gain preamp tube because I don't want to lose any gain on my distortion channel. Would it just give me more clean headroom and keep my distortion high gain?

 

I've read a lot about 6L6 clean breakup and was wondering if my power tubes could be responsible as well.... just not sure which tubes I should replace if I want to retain the high gain but get more clean headroom.

 

Thanks

[NaturalBornBoy]

Why don't you try a 5751 in the preamp slot that affects only the clean channel?

[pioneerprogress]

 

if at7's are too big of a jump (which most people find they are) you can use a 5751, or a 12au7.

 

 

I thought 12au7's are even bigger difference than 12at7?

[BornUnderBadSgn]

 

I thought 12au7's are even bigger difference than 12at7?

 

 

You are correct.

[Curtis.Fagan]

 

Yea it does thanks. I guess I just don't want to replace a 12Ax7 with a lower gain preamp tube because I don't want to lose any gain on my distortion channel. Would it just give me more clean headroom and keep my distortion high gain? I've read a lot about 6L6 clean breakup and was wondering if my power tubes could be responsible as well.... just not sure which tubes I should replace if I want to retain the high gain but get more clean headroom. Thanks

 

 

I think you might be able to put a lower gain pre in your amp and still retain the "feel" of high gain. The MTS is a gainiac of a head. It'll quiet it down and take some of the fizz out of it, but you'll still retain the growl while only taming the snarl a little...

 

I would also motion that if you want big, fat and smooth, try KT77's perhaps. I find they are a good middle ground for 6L6's and EL34's, and can keep a nice, glassy clean with no problems, and open up like a lions throat when you punch into the heavy stuff... assuming you can make that kind of swap with the MTS3200.

 

-Curtis

[LA-Ü-RA]

 

Why don't you try a 5751 in the preamp slot that affects only the clean channel?

 

 

It made a pretty big difference in my Nitro (I just got a few yesterday). Cleaned up my clean channel quite well.

[dgc480]

thanks guys the 5751 in the clean slot that sounds like just what I need. However, I'm new to this tube stuff so I'm not sure which preamp slot is the one that affects only the clean channel. Is it V1?

So what 5751 would you suggest?

[the_bleeding]

 

I thought 12au7's are even bigger difference than 12at7?

 

 

my bad. my head was on another planet.

[dgc480]

Hey so I've talked to a bunch of guys at online tube stores about the problem. I'm getting mixed reviews, but most of them say that the power tubes are the ones that will cause clean breakup. There's something called the milliamp rating, and apparently a lower milliamp rating has less headroom, whereas a higher milliamp rating has more headroom. However, I've also heard the opposite....which way is it? My power tubes are rated at 17, which is pretty low. Would this cause me to have less headroom?

[BluesMan60]

 

if at7's are too big of a jump (which most people find they are) you can use a 5751, or a 12au7.

 

 

I think you're confusing 12AT7s and 12AU7s.

 

http://www.kcanostubes.com/content/newsletter_details.asp?ArticleID=4

 

Mike K

KCA NOS Tubes

[BluesMan60]

Hey so I've talked to a bunch of guys at online tube stores about the problem. I'm getting mixed reviews, but most of them say that the power tubes are the ones that will cause clean breakup. There's something called the milliamp rating, and apparently a lower milliamp rating has less headroom, whereas a higher milliamp rating has more headroom. However, I've also heard the opposite....which way is it? My power tubes are rated at 17, which is pretty low. Would this cause me to have less headroom?

 

Lower current (as measured by milliamps) means earlier breakup. The number 17 doesn't tell us much as there's no absolute rating system, they're all relative. Every dealer uses a different method for rating tubes.

 

Setting you bias too hot will make the power section break up sooner. Try setting the bias for 30-35 mA.

 

Mike K

KCA NOS Tubes

www.kcanostubes.com

[dgc480]

Hey thanks Mike. The thing is, my bias is still at the stock bias, which is 25ma per power tube. That's pretty cold, so I'm wondering what could be causing the clean breakup...

The scale I heard when talking to the guy I bought the tubes from was something like 15-30, so 17 would be pretty low.

 

So if the bias isn't too hot, my clean breakup could be only from two causes.

1. the 6L6GCs have too low of a milliamp rating

2. My 12AX7s are too high gain and I need a 5751 in V1

 

I've heard mixed opinions on whether it's the power amp or preamp tubes. Some people say a 5751 in V1 will fix it, whereas others say the power tubes are responsible for early breakup (low milliamp rating). Which one is it?

 

thanks,

Dylan

[ringo11]

I would lean toward something low-ish in V1 but also check V? which ever is termed the driver circuit. In my amp its V3, which is where I put a clean "matched" JAN GE tube. If your running at high volume levels you will certainly have power tube saturation.

[guitarcapo]

In my opinion if you go too low on the gain factor on V1 you lose some brightness even though it's cleaner. Less sparkle/more sterile.

[BluesMan60]

 

Hey thanks Mike. The thing is, my bias is still at the stock bias, which is 25ma per power tube. That's pretty cold, so I'm wondering what could be causing the clean breakup... The scale I heard when talking to the guy I bought the tubes from was something like 15-30, so 17 would be pretty low. So if the bias isn't too hot, my clean breakup could be only from two causes. 1. the 6L6GCs have too low of a milliamp rating 2. My 12AX7s are too high gain and I need a 5751 in V1 I've heard mixed opinions on whether it's the power amp or preamp tubes. Some people say a 5751 in V1 will fix it, whereas others say the power tubes are responsible for early breakup (low milliamp rating). Which one is it? thanks, Dylan

 

 

Could be either, both, or neither. Speakers and the overall amp design matter a lot too. Also, how hot your pickups are.

 

Higher rated power tubes are worth a shot as are lower gain preamp tubes.

[dgc480]

ok gotcha. That's sort of what I figured. So I just need to swap the new power tubes and new preamp tubes out for the old ones and see which ones gives me more headroom, then I'll know whether I need to change the power tubes or change the preamp tubes. thanks guys

[guitarbilly74]

 

Hey so I've talked to a bunch of guys at online tube stores about the problem. I'm getting mixed reviews, but most of them say that the power tubes are the ones that will cause clean breakup. There's something called the milliamp rating, and apparently a lower milliamp rating has less headroom, whereas a higher milliamp rating has more headroom. However, I've also heard the opposite....which way is it? My power tubes are rated at 17, which is pretty low. Would this cause me to have less headroom?

 

 

ehhh I don't know about that... with a 100w power amp with 4 6L6s you should have plenty of headroom unless your tubes are bad or you are playing EXTREMELY loud..

 

I still say a 5751 in v1 and a 12AT7 in V5 would give you the results you want.

[BluesMan60]

ehhh I don't know about that... with a 100w power amp with 4 6L6s you should have plenty of headroom unless your tubes are bad or you are playing EXTREMELY loud.. I still say a 5751 in v1 and a 12AT7 in V5 would give you the results you want.

 

I tend to agree, but with low rated power tubes he's probably not getting the full 100 watts. Everything plays a role.

 

Mike K

KCA NOS Tubes

www.kcanostubes.com