V1 Preamp Tube Is Dim, But Sounds Fine.

[Rick Lee]

Instead of further hijacking the Incoming SLO thread, I thought I'd start another. I was complaining in that thread about my SLO being super noisy at high volume. When OD volume is at 7 and guitar volume is all the way down, the amp sounds like standing on the beach at high tide. Very noisy.

On Reza suggestion I got a JJ ECC803S gold pin and put it in V1. Damn - that was $30. As soon as I turned it on, it flared, almost flashed and then was dim. I took the covers off the other preamp tubes and turned the lights out. I played at 7 for a while, which is insanely loud. The new tube is barely lit, while the others shine bright. It sounds great, is still noisy, but I'm guessing it's a different issue. Anyway, is this tube good or gonna last?

 

[Racerxrated]

I've always heard bad things about JJ tubes reliability but no personal experience. But, if it still sounds good? I've never had a tube do that but then again, I don't watch it fire up unless I'm rebiasing and have the chassis out. Must be working fine if it sounds like it should.

 

[sjk]

Instead of further hijacking the Incoming SLO thread, I thought I'd start another. I was complaining in that thread about my SLO being super noisy at high volume. When OD volume is at 7 and guitar volume is all the way down, the amp sounds like standing on the beach at high tide. Very noisy.

On Reza suggestion I got a JJ ECC803S gold pin and put it in V1. Damn - that was $30. As soon as I turned it on, it flared, almost flashed and then was dim. I took the covers off the other preamp tubes and turned the lights out. I played at 7 for a while, which is insanely loud. The new tube is barely lit, while the others shine bright. It sounds great, is still noisy, but I'm guessing it's a different issue. Anyway, is this tube good or gonna last?

I doubt that anything is wrong with the tube. Some preamp tubes do that light up initially and then are lit very dimly unlike most 12ax7's. One off the top of my head I can think of are EI 12ax7's and I know there are others. I have some of those ecc803's but without the gold pin and will pop one in an amp later and check to see what it does. Btw as far as I have heard most of those gold pin tubes are marketing deals where they can charge you more but does not improve on the regular.

 

[Beam Tetrode]

Some tubes will flash on start up. This is because filament resistance is low when cold. It's also normal for the SLO to hiss as preamp gain is increased. It's mostly due to AC heater supply on V1, and the huge amount of unattenuated V1 gain.

 

[hatrick00]

Instead of further hijacking the Incoming SLO thread, I thought I'd start another. I was complaining in that thread about my SLO being super noisy at high volume. When OD volume is at 7 and guitar volume is all the way down, the amp sounds like standing on the beach at high tide. Very noisy.

On Reza suggestion I got a JJ ECC803S gold pin and put it in V1. Damn - that was $30. As soon as I turned it on, it flared, almost flashed and then was dim. I took the covers off the other preamp tubes and turned the lights out. I played at 7 for a while, which is insanely loud. The new tube is barely lit, while the others shine bright. It sounds great, is still noisy, but I'm guessing it's a different issue. Anyway, is this tube good or gonna last?

the tube is most likely fine, i have had some chinese 12ax7bs do the same, flash on startup, you cannot judge a pre tube by it's brightness.

 

[LP Freak]

It's perfectly normal to flash on start up and to be very dim. If it sounds good, it is.

 

[Rick Lee]

Ok, thanks guys.

 

[Jack Luminous]

Some tubes will flash on start up. This is because filament resistance is low when cold. It's also normal for the SLO to hiss as preamp gain is increased. It's mostly due to AC heater supply on V1, and the huge amount of unattenuated V1 gain.

AC heater causes hum, not hiss. I read the other thread about the SLO being noisy and really I don't understand. My 3 amps at the moment being a '82 2203, an early dual recto and a rackmount SLO, the SLO is certainly the quietest of the three. If preamp gain is high and volume insane, it's normal to get some hiss. The question is : is this amount normal ? For the SLO, I think the amount of hiss is very low.

 

[Rick Lee]

My OD gain is between 6-7. It's quiet unless I really crank up the volume. Obviously, it's extremely rare that I play at 7. But I'd like to have it quiet when I do. My EVH and Marshall are far more quiet at high band volume.

 

[Beam Tetrode]

Some tubes will flash on start up. This is because filament resistance is low when cold. It's also normal for the SLO to hiss as preamp gain is increased. It's mostly due to AC heater supply on V1, and the huge amount of unattenuated V1 gain.

AC heater causes hum, not hiss. I read the other thread about the SLO being noisy and really I don't understand. My 3 amps at the moment being a '82 2203, an early dual recto and a rackmount SLO, the SLO is certainly the quietest of the three. If preamp gain is high and volume insane, it's normal to get some hiss. The question is : is this amount normal ? For the SLO, I think the amount of hiss is very low.

You're right. Hiss could be Johnson noise from the 68K input grid resistor. I know Mesa commonly uses a ferrite bead instead of a grid resistor.

 

[guitarplayerone]

If you have other tubes around (even switching the ones already in the amp), why not shift them around and see if you can't find a pattern?

 

[lespaul6]

The 803s is a long plate spiral tube... due to the construction of the tube you will not see it glowing same thing with the sovtec LPS...great tubes I use them in my amps. They can be hit or miss regarding microphonics.