# New Member w/ Egnater Rebel 30 Issues [VIDEO]



## -MJD- (Dec 20, 2014)

Hi all, 


I'm having some issues with my amp, so I've signed up to a few guitar forums hoping to find an answer. To give you a bit of background on myself, first and foremost I think you should know that I'm a drummer. Please don't throw things at me. As such, I don't know too much about guitar gear or the technical side of guitar amps, although I'm not incompetent. So it's entirely possible that these "issues" aren't issues at all and are totally normal, but I don't think that's the case.


Here are my problems:


1) Channel 1 has a hum/buzz/static sound, even with nothing plugged in. The sound is much louder than Channel 2, even though Channel 2 is higher gain than Channel 1 and set to the same volume. This makes Channel 1 completely useless to me, as I primarily purchased this amp to do silent recording since I live in a small condo. Channel 2 in comparison is almost completely silent.


2) If I tap on the amp head, a rattling sound comes through the cab pretty loudly. It doesn't matter where I tap on the amp, and knob or switch positions do not make any difference. This doesn't seem normal to me. Please, no "smart guy" comments like "Well, don't tap it and it won't happen anymore." There are no audible physical rattles coming from the amp itself. And later in the video, I just flick the Channel switch and the sound still comes through, and it's so light that I don't think any vibrations through the amp are the cause of the sound.


I have already replaced each and every tube one by one and there was no difference. I also have a Fender Champion 600 and a Vox VR30, both of which are dead silent. I understand that I can go to a music store or guitar amp technician, but with it being so close to Christmas, I'd rather not trek out there at this time... but I'm curious to see if anyone might know what the cause is just by watching the video.


Here's the video: http://youtu.be/-dU9dRujvKo


Thanks for reading and watching, and any help would be greatly appreciated.


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## Steadfastly (Nov 14, 2008)

I am not an amp expert by any means but there has got to be something loose inside causing the noise with the tapping sound.

Take heart, there will be some help with the more knowledgeable members coming through soon.


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## -MJD- (Dec 20, 2014)

Steadfastly said:


> I am not an amp expert by any means but there has got to be something loose inside causing the noise with the tapping sound.
> 
> Take heart, there will be some help with the more knowledgeable members coming through soon.


Thanks. In the meantime, I've done a lot of searching and reading and found that Channel 1 hiss is a very common problem. I suppose I could have saved myself the headaches by searching first. So I'll chalk that up as "normal". But the tapping sound is a whole other ball of wax....


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## Bubb (Jan 16, 2008)

I'm no amp tech either but troubleshooting...have you checked for a loose output jack and tried a different speaker cable to eliminate these ?

If it's new,and not the speaker cable,I'd return it.


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## nonreverb (Sep 19, 2006)

I just had one of these in the shop. All the power tubes sounded like a baby rattle. I had to replace them all. I'm afraid to tell you but that tap rattle is a power tube....a very loose power tube. Take each one out and gently tap it with your finger while listening.....you'll find it.


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## -MJD- (Dec 20, 2014)

Well folks, I have to admit something. I only had one replacement of each EL84 and 6V6. As such, when I was doing my tests replacing tubes one by one, there was always one of the original EL84s and one of the original 6V6s plugged in. I figured if it were to be a tube issue, it was going to be one faulty tube. It was both EL84s. I also wrongly assumed that if the tube mix knob was 100% at 6V6, the EL84s would have been taken out of the signal path entirely, so I ruled out power tubes early on when I realized the sound happened regardless of which tube mix setting I had set. I swapped both EL84s with a new pair and now the amp is silent when tapped. This is how you learn.


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## -MJD- (Dec 20, 2014)

So onto issue #1, the channel 1 hiss. 

I decided to play around with a few other preamp tubes and my SPL meter right up on the speaker touching the grill cloth. With all the stock tubes and volume, treble and bass full on Channel 1 with nothing plugged in, I get about 66-67db of hiss. I tried a the stock Sovtek, a Groove Tube, an EHX, a Mullard and a cheap Chinese 12AX7 in V1. The Chinese tube was microphonic so I pitched it. The Sovtek and EHX put out 66-67db of hiss in V1. The Mullard put out 68-69db in V1. The GT put out 69-70db in V1. I also found a GE 12AT7 in my collection, put that in V1, and got 64-65db of hiss. So barely any differences swapping tubes in V1.


Then I moved onto V3. The Sovtek and EHX put out 65-66db in V3, the Mullard put out 66-67db in V3, and the GT put out 68-69db in V3. Then I tried the GE 12AT7 in V3. 52db of hiss! That's a 15db drop - about half the perceivable hiss than I started with. And the tone is good to me - more headroom and more sparkly hi-fi sounding clean.


I'm happy. Call this one closed.


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## keto (May 23, 2006)

Great work, Sherlock! (no sarcasm intended whatsoever). Love hearing a happy ending, and that you took the time to DIY and experiment. AND acknowledged a mistaken approach re: power tubes. All sorts of win here :applouse:


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## davetcan (Feb 27, 2006)

Well done indeed. Looking at this schematic it looks like V3 was the place to start given the symptoms.

http://www.egnateramps.com/EgnaterProducts/Rebel/Rebel30/Rebel30Specifications.html


and welcome to the forum, drums and all


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## jb welder (Sep 14, 2010)

Just a couple observations: the tube you trashed because it was microphonic in spot #1 may be fine for other spots in the amp.
The first or high gain stages will often need tubes that are hand picked for low microphonics. But tubes that are microphonic in these spots are not necessarily bad. They will often work fine in lower gain positions. Or for tremolo position where there is no actual audio passing through the tube and microphonics will have no effect.
Many tube distributors will no longer accept returns for microphonic tubes, so you have to grade what you have for microphonics, and use them appropriately.
The fix you found by using a 12AT7 in a 12AX7 spot worked because you decreased the gain in that stage. So along with less noise, there is less gain. I assume you knew this but thought I would point it out for others reading this. You might want to try a few lower gain types to see which you like best, for example: 12AT7, 12AY7, 12AU7, 5751


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## -MJD- (Dec 20, 2014)

jb welder said:


> Just a couple observations: the tube you trashed because it was microphonic in spot #1 may be fine for other spots in the amp.
> The first or high gain stages will often need tubes that are hand picked for low microphonics. But tubes that are microphonic in these spots are not necessarily bad. They will often work fine in lower gain positions. Or for tremolo position where there is no actual audio passing through the tube and microphonics will have no effect.
> Many tube distributors will no longer accept returns for microphonic tubes, so you have to grade what you have for microphonics, and use them appropriately.
> The fix you found by using a 12AT7 in a 12AX7 spot worked because you decreased the gain in that stage. So along with less noise, there is less gain. I assume you knew this but thought I would point it out for others reading this. You might want to try a few lower gain types to see which you like best, for example: 12AT7, 12AY7, 12AU7, 5751


Thanks. The cheap Chinese tube that I tossed out was the stock tube pulled from my Vox VR30R when I upgraded that tube. So not only was it microphonic, I figured if I pulled it from my "second" amp, why would I want to use it in my "first" amp? As for the 12AT7, I do know that I decreased the gain, but I think I like it better. My cleans are more clean, I have a lot more headroom, and if I wanted to add some grit, I could either do it with pedals, or switch over to Channel 2 which doesn't have hiss issues to begin with. I think I have a 12AU7 in one of my tube mics that I could test out if I wanted, but I think it'd be too flat and lack character. Next time I have it open I'll experiment some more. For now I'll leave it as is and quit while I'm ahead.


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