5F6A problem?

[Dave H]

I think V1 is noisy. I'd either replace it or use it in a later stage of the amp where the noise will be amplified less.

[vinceg]

Hi, I replaced the V1 and the hum is disappeared. Virtually appears to be off. It's silent.
Thank's to all!!!

[vinceg]

When I turned on the amp with the new V1 raising the volume of the hiss was imperceptible. But recently, after playing a bit at low volume, I increased the vol pot to maximum and the breath was more accentuated. It 's normal that the heating tube is more noisy? In addition, with the old V1 tube the hiss was stronger with the Normal volume, now the hiss is louder with Bright Volume. Why is this?

[vinceg]

Some pictures!

[eschertron]

Nice work there, Vincenzo, and welcome to the forum!

I think you've discovered what has been hinted at here and discussed in other threads, that modern production tubes are "all over the place" with regard to quality. You may have to continue swapping your preamp tubes between positions, and maybe even get another tube or three before you find the quietest combination. I've heard this technique referred to as 'tube rolling'. Keep in mind that the tube closest to any input (electrically) will have its grid signal amplified the most. If you have more than 1 input tube (sounds like you do, if you have both a normal and bright channel), then both are subject to the amplification.

[vinceg]

Nice work there, Vincenzo, and welcome to the forum!

I think you've discovered what has been hinted at here and discussed in other threads, that modern production tubes are "all over the place" with regard to quality. You may have to continue swapping your preamp tubes between positions, and maybe even get another tube or three before you find the quietest combination. I've heard this technique referred to as 'tube rolling'. Keep in mind that the tube closest to any input (electrically) will have its grid signal amplified the most. If you have more than 1 input tube (sounds like you do, if you have both a normal and bright channel), then both are subject to the amplification.

Thank you very much!!
Anyway, the hiss is less than the old tube and when I play guitar I do not feel it. Unfortunately, I'm a perfectionist but i have to convince myself that I did a good job and I can not expect the moon.

[Chuck H]

Hiss is a very normal part of high gain amplifier tone (and even when they're not distorted they are high gain). You will never eliminate it. As I mentioned before, place your amp next to a similar amp set to the same gain level and compare. If the hiss on your amp is much higher then keep trying tubes. Don't throw away the replaced tubes though. They can often be used in later gain stages without the same level of consequence.

[vinceg]

Hi guy, I want you to listen some audio samples of my amp but I do not know how I do to upload this file in the forum.
I'm not completely satisfied of my amp. It have a beautiful sound but the hiss of V1 tube is annoying.
I have replaced a EH 12AY7 with a expensive 12AY7 TAD but after only one day it is very noise.
I understand that if I install a 12AX7 in V1 the amp is very silent. The hiss is significantly lower than 12AY7.
I have tried several 12AY7 and the result is the same, but with 12AX7 is ok!!
unfortunately I not love tha 12AX7 sound, it is too gain.
Can you help me?

[Chuck H]

When posting go to "advanced" then click "manage attachments" Then click "add files" then click "browse". Now you need to find the file on your computer and click on it. In the new box that pops up click "open". Then back on the attachments screen the file name should appear in the browse/add box upper right. Click "add". The file should appear on the screen in your files box (center) and in the post box (bottom). Click "done" and the file should be added to the post though it won't show in the text box. Now click "submit" to add the post and file to the thread.

I don't understand why your amp would hiss unpleasantly. Hiss is a normal consequence of amplification. Is this amp especially bright? Does it seem to be loud enough? Is there any other thing about operating the amp that seems wrong to you and do you have the experience to know what sounds right? That is, have you played through other amps at the same volume before and do you know how loud this amp should be? Do you use any effects at the input? Is your guitar passive or does it use a preamp?

[vinceg]

These are samples of how it sounds. All the sample are registered with only amp, without effects. My guitar is a Stratocaster with three single coil.
Sorry for my poor execution.
The "voce009" is registered with vol at 4.
The other files are registered with vol almost to the max.
Yuo can listen, in this case, the hiss.
judge for yourself

[Chuck H]

Nice! Glad you got the samples up. But I need to say, for any watchers who think I'm fielding this one, my sound system is not presently on my computer so I can't listen to the sound samples! I hope to have my sound system back in a day or two.

[vinceg]

Nice! Glad you got the samples up. But I need to say, for any watchers who think I'm fielding this one, my sound system is not presently on my computer so I can't listen to the sound samples! I hope to have my sound system back in a day or two.

Ok, I'll wait!!

[g1]

It have a beautiful sound but the hiss of V1 tube is annoying.
I have replaced a EH 12AY7 with a expensive 12AY7 TAD but after only one day it is very noise.
I understand that if I install a 12AX7 in V1 the amp is very silent. The hiss is significantly lower than 12AY7.
I have tried several 12AY7 and the result is the same, but with 12AX7 is ok!!
unfortunately I not love tha 12AX7 sound, it is too gain.

It sounds like the TAD 12AY7 was ok for a day, then became noisy?
Now, all your 12AY7's are noisier than 12AX7's? Normally, I would expect the 12AX7's to be noisier as they will provide more gain in the V1 position.
It sounds like you have a bad bunch of 12AY7's, or you just can't get quiet ones any more.
But, it is possible something in the circuit is causing them problems.
What is the heater voltage (AC) at the V1 socket?
What are the DC voltages at pins 1,2,3,6,7,8 of V1 with 12AX7?
What are those same pins with 12AY7?

[eschertron]

+1 to g-one's comments.

My comments about noise in general. I listened to the clips, and I have no complaints about what you played. David Gilmour is one of my favorite artists! Nicely done! However, being able to compare your tone to the recordings, I'd venture that you've got more distortion dialed in than the original. This will boost any noise from the input stage on through, and your result will be 'hissy-er' than you'd like.
Is there a master volume on your amp? I wonder what the noise would sound like under club conditions. I'd hazard a guess that a little less gain at the beginning of the signal chain (and make-up gain from the power section) would make any hiss less apparent. These are general comments, nothing about any problems you might be having with the tubes. JM2C

[Chuck H]

I need to +1 on the commentary so far. It seems like anyone who gets into "whole amp" distortion troubles about noise early on. A whole amp at volume creating a lot of gain has a butt load of hiss!!! Not more than any other amp mind you, but the amp now in question is LOUDER! So the hiss is louder. I don' know why but this never got past me. I played most of my youth with Marshall's and RAT boxes! When I got to playing in a band I realized that noise control was part of the game. I recognized right away that hiss is directly proportional to gain at volume. And when put in perspective I noticed that the hiss of an overdriven amp at volume is generally LESS than the hiss of a distortion pedal through an amp at similar clipping and volume levels. You need to be really "apples to apples" to recognize it, but it's true. Obviously a master volume amp with a high gain preamp will have less hiss at similar gain AT A LOWER VOLUME!!! It's when all things are created equal that the picture comes into focus.

BTW, I haven't heard the clips yet. Maybe tomorrow?!?