Post by driventone on Feb 16, 2022 19:28:15 GMT -7
**Disclosure - this is not a complaint. What I was hearing was totally tolerable and not that noticeable. I was just curious what was causing it, specifically.**
I've been driving myself batty for a couple days. I got my Monza combo last week, and it sounds glorious. However, there's a slight ringing/rattling on some notes. Not enough to make me dislike the amp, but I'm a problem solver by nature so I have to figure it out, or at least understand where it was coming from.
Don from Dr. Z let me know that the tube in V1 of my amp had some microphonics to it, but it was minor and he left it in because it sounded good. He's right - it's an old RCA 12AT7 (which may explain something - lower gain, smoother sound, if that's what you like), and it does sound good, to me as well. I swapped it out with an old Mullard ECC83, and it seemed to be a bit better. So I'm pretty sure that tube did have some microphonic properties.
However, I could still hear a bit of ringing, especially on certain notes. I have read the Doc's rant on this subject, and full disclosure, although I’m in more than my underwear, I am admittedly 2 feet from the amp. So I’m 100% guilty there. And this isn’t a complaint, more a function of my personality to want to know what makes something tick, and curiosity had gotten the best of me. I wanted to see if I could track it down.
I went down the rabbit hole of tube-rolling: changing out my 6n14n's for the EL84's that used to be in it, going through 7025's, 12AX7's, just about anything I had. I set up a looper and played the notes that made it ring the most, and I noticed the ringing was louder behind the amp. I reached into the cab to put my finger/hand on different things. I thought that putting my hand on the back of the Red Fang calmed it down, so I pulled it to inspect, bolted it back in and tightened it using an alternating pattern. I tightened the baffle too.
It persisted, so I turned my attention to the metal shielding tape under the top of the cab where the chassis goes - the edges aren’t sticking to the top of the cab, and I thought *maybe* it could be fluttering?
Ok, that was crazy talk. It was at this point that I did the thing I should have done first - plug it into another cab. I have an ‘83 JCM 800 combo that I used as a cab. No rattle or ringing. Then, I plugged the JCM into the Monza speaker… IT RATTLED! I knew it wasn’t that shielding tape, so I thought, you know what? I’m going to pull the Monza’s tubes one at a time while playing the JCM 800 through it, and see if the rattling goes away.
Until this point I had only been looking at the preamp and power tubes. But I never thought to look at the rectifier. I pulled it out and shook it - JINGLE BELLS. I don’t even have to hold it up to my ear. Without the rectifier tube in the Monza, and with the Marshall plugged into the Monza cab, no rattle even when I let ‘er rip!
Now it all makes sense. After taking out the microphonic preamp tube, the only ringing I was hearing was coming from the cab, not through the speaker. Obviously, I can’t test the Monza with no rectifier, but I’m sure that’s what I was hearing.
Here are my questions:
1. Has anyone ever noticed this before?
2. Are tube dampers worth it on rectifier tubes? I’m not sure it would help anyway, because even when I wrap my whole hand around the tube tightly and shake it, I can hear the rattle/ringing.
3. I see that the Doc recommends the Sovtek 5AR4, which this is. I bet it’s original - this is a 12 year old combo, maybe the tube has been shaken, rattled and rolled loose inside through years of rockin’. Plus it just took a trip from New Jersey to Ohio to California. I’m willing to try another Sovtek. Does anyone have thoughts on the Groove Tubes 5AR4? They’re in stock at Guitar Center near me.
Thanks for reading!
Ryan
I've been driving myself batty for a couple days. I got my Monza combo last week, and it sounds glorious. However, there's a slight ringing/rattling on some notes. Not enough to make me dislike the amp, but I'm a problem solver by nature so I have to figure it out, or at least understand where it was coming from.
Don from Dr. Z let me know that the tube in V1 of my amp had some microphonics to it, but it was minor and he left it in because it sounded good. He's right - it's an old RCA 12AT7 (which may explain something - lower gain, smoother sound, if that's what you like), and it does sound good, to me as well. I swapped it out with an old Mullard ECC83, and it seemed to be a bit better. So I'm pretty sure that tube did have some microphonic properties.
However, I could still hear a bit of ringing, especially on certain notes. I have read the Doc's rant on this subject, and full disclosure, although I’m in more than my underwear, I am admittedly 2 feet from the amp. So I’m 100% guilty there. And this isn’t a complaint, more a function of my personality to want to know what makes something tick, and curiosity had gotten the best of me. I wanted to see if I could track it down.
I went down the rabbit hole of tube-rolling: changing out my 6n14n's for the EL84's that used to be in it, going through 7025's, 12AX7's, just about anything I had. I set up a looper and played the notes that made it ring the most, and I noticed the ringing was louder behind the amp. I reached into the cab to put my finger/hand on different things. I thought that putting my hand on the back of the Red Fang calmed it down, so I pulled it to inspect, bolted it back in and tightened it using an alternating pattern. I tightened the baffle too.
It persisted, so I turned my attention to the metal shielding tape under the top of the cab where the chassis goes - the edges aren’t sticking to the top of the cab, and I thought *maybe* it could be fluttering?
Ok, that was crazy talk. It was at this point that I did the thing I should have done first - plug it into another cab. I have an ‘83 JCM 800 combo that I used as a cab. No rattle or ringing. Then, I plugged the JCM into the Monza speaker… IT RATTLED! I knew it wasn’t that shielding tape, so I thought, you know what? I’m going to pull the Monza’s tubes one at a time while playing the JCM 800 through it, and see if the rattling goes away.
Until this point I had only been looking at the preamp and power tubes. But I never thought to look at the rectifier. I pulled it out and shook it - JINGLE BELLS. I don’t even have to hold it up to my ear. Without the rectifier tube in the Monza, and with the Marshall plugged into the Monza cab, no rattle even when I let ‘er rip!
Now it all makes sense. After taking out the microphonic preamp tube, the only ringing I was hearing was coming from the cab, not through the speaker. Obviously, I can’t test the Monza with no rectifier, but I’m sure that’s what I was hearing.
Here are my questions:
1. Has anyone ever noticed this before?
2. Are tube dampers worth it on rectifier tubes? I’m not sure it would help anyway, because even when I wrap my whole hand around the tube tightly and shake it, I can hear the rattle/ringing.
3. I see that the Doc recommends the Sovtek 5AR4, which this is. I bet it’s original - this is a 12 year old combo, maybe the tube has been shaken, rattled and rolled loose inside through years of rockin’. Plus it just took a trip from New Jersey to Ohio to California. I’m willing to try another Sovtek. Does anyone have thoughts on the Groove Tubes 5AR4? They’re in stock at Guitar Center near me.
Thanks for reading!
Ryan