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Post subject: Re: Help with DRRI noise...
Posted: Tue Nov 22, 2011 7:29 pm
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As stratele52 suggested, start on the far right. The 12AT7 that you pulled, closest to the output tubes is the PI, and pulling that tube eliminates the signal from all tubes before it, it is the last tube that you want to try. It could still be that tube causing the problem, but test the tubes in order starting from the right. :idea:

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Post subject: Re: Help with DRRI noise...
Posted: Tue Nov 22, 2011 7:55 pm
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shimmilou wrote:
As stratele52 suggested, start on the far right. The 12AT7 that you pulled, closest to the output tubes is the PI, and pulling that tube eliminates the signal from all tubes before it, it is the last tube that you want to try. It could still be that tube causing the problem, but test the tubes in order starting from the right. :idea:


Thank shimmilou -- that's what I did...the preamp tube closest to the output tubes was the last one that I pulled. I started on the far right and went one tube at a time. When I pulled the V4 tube (fourth from right, third from left) the hiss in the Vibrato channel stopped. And when I pulled the last preamp tube, V6 (sixth from right, first from left), the hiss in the Normal channel stopped.


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 3:20 am
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I write you to start at RIGHT not left from the back of the amp.

Do some other test , your firts test is wrong.
Please follow carrefully what I write if you want to know what is wrong with the amp


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 4:34 am
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stratele52 wrote:
I write you to start at RIGHT not left from the back of the amp.

Do some other test , your firts test is wrong.
Please follow carrefully what I write if you want to know what is wrong with the amp


Thanks stratele, I did start from the right. I started from the right -- fartherest from the power tubes -- and pulled one tube at a time. The fourth tube stopped the Vibrato hiss and the sixth tube that I pulled, the one closest to the power tubes, stopped the hiss on the Normal channel.

Let me re-state my results in the order in which I did them (I realize that I created confusion by misstating the order in my post above, which I have corrected):

OK -- here are the results:

Starting at the right, the hiss did not go away when I removed (and replaced) the first three preamp tubes.

The hiss on the Vibrato channel stopped when I removed the fourth preamp tube from the right. The diagram says it is a 12AX7A. The tube that I pulled out is a GrooveTube ST-ECC83-S.

The hiss on the Normal channel stopped when I removed the sixth preamp tube, the one that is located closest to the power tubes. The diagram says it is a 12AT7. The tube that I pulled out is a GrooveTube GT-ECC81-S.

So, a trip to GC for replacements should solve the hiss problem, yes?


Last edited by Cotton121 on Wed Nov 23, 2011 5:04 am, edited 1 time in total.

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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 5:01 am
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Good,

Your 12AT7 could be noisy, try a new one is the only and easiest thing to do for now.

You could also buying a 12AX7 for other channel.

I can't be sure a new tubes stop the hiss. You try that or find a better shop for repair on warranty.
It is always useful to have spair tubes.


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 5:19 am
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stratele52 wrote:
...find a better shop for repair on warranty.


Thanks for your help, stratele. I am totally mystified by two of the "best" amp shops in Nashville telling me that hiss is "normal tube noise." As Ajay puts it, I want mine to be "quiet as a church mouse." My thanks to you for taking the time to reply -- although this amp problem is frustrating, I enjoy learning from the people on this forum. Thanks...


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 5:34 am
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I am happy to help you. It's not easy writing without being able to see and hear the amp personally.
There remains the question of whether your "hiss" is normal or not. If the amp is really bad or if it is bad desing built, and we must live with or if you demand the impossible?

You have often heard tube amps to compare?


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 5:54 am
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stratele52 wrote:
You have often heard tube amps to compare?


Yes, my Blues Deluxe did not make this hiss noise. And our Orange Tiny Terror is "quiet as a church mouse." :)


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 6:19 am
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So this amp have a problem for sure. You have enough experience with tubes amps.

If you can, use some of your tubes from your other amps to replace those in DDRI, to test.


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 7:13 am
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Cotton121,

The ECC83 is just the European designation for the equivalent to a 12AX7, and the ECC81 is the equivalent to 12AT7. :idea:

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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 8:27 am
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shimmilou wrote:
Cotton121,

The ECC83 is just the European designation for the equivalent to a 12AX7, and the ECC81 is the equivalent to 12AT7. :idea:


OK -- thanks shimmilou.

I'm headed to GC this morning and have fingers crossed that new tubes in V4 and V6 will stop the unwanted hiss. My only fear now is that the hiss stopped just because I removed the tube from that particular position ... and not because the tubes are faulty. We'll know soon!

Many thanks for your help and input...


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 8:34 am
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Come back with news and good luck


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 4:55 pm
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Update: I replaced the 12AX7 tube in V4 ... and the hiss problem improved slightly. GC did not have a compatible 12AT7, so I was unable to change out the tube in V6.

In the meantime, I'm working on training my ears to filter out the unwanted hiss. :)


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 5:09 pm
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You don't have a 12AT7 / ECC81 on your others amps ?

Hiss is worst with a new 12AX4 in V4 !!!!!!

Try this one in place of 12AT7, see what you ear


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Post subject: Re: Help with DRRI noise...
Posted: Wed Nov 23, 2011 6:46 pm
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stratele52 wrote:
You don't have a 12AT7 / ECC81 on your others amps ?

Hiss is worst with a new 12AX4 in V4 !!!!!!

Try this one in place of 12AT7, see what you ear


stratele ---

The hiss is lower and less noticeable with the new 12AX7 in V4. Yeah!

No, I do not have another amp with a 12AT7. I traded-in the Blues Deluxe on this Deluxe Reverb. And the Orange Tiny Terror has two 12AX7.

I'm not clear on your comment about a "new 12AX4 in V4." I don't have a 12AX4 in V4 ... only a 12AX7.

Thanks...


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