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Post by fishbeiner on May 25, 2022 13:53:05 GMT -7
Recently acquired an M12 head and 1x12 cabinet. While playing it, I noticed there was a fizziness under the notes. As I have played several other examples of the M12, I know that this is not a normal occurrence.
I started a thread in the tube section, as I had a feeling that the issue involves needing a new tube or two. However, after replacing all of the tubes, the issue still remained.
I figure posting here with solicit a broader assistance in problem-solving.
While attempting to locate the source, I have done the following: - replaced all of the tubes with similar replacements - tried 4 different guitar cables - tried three different speaker cables - used three different guitars - used a voltage regulator to bring the voltage down to 120 (I believe at the wall it’s 124-127) - moved the head a few feet away from the cab - checked the speaker cab for any loose pieces
None of the above helped and the fizziness still remains.
The only thing I do not have, is a spare speaker. I did pull out the 8 ohm Creamback out of the cab, connecting it bare to the amp in order to rule out the cab. Still there.
I recorded two clips with my phone. Although more slightly more apparent with the speaker out of the cab, the clips presents a fairly accurate presentation of the issue. In the Clips, the M12 is set: Volume slightly below 9 o’clock, Bass at 11 o’clock, Treble at 1 o’clock. Guitar is a Fender Strat with Fender Lace pickups. Bridge position.
Hoping to get some further assistance in troubleshooting. Thanks!
****had some issues with the clips, but I think it’s fixed. Let me know if anyone has issues.
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Post by premiumplus (Dave) on May 25, 2022 13:59:50 GMT -7
Your phone isn't anywhere close to the amp or guitar, is it?
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Post by fishbeiner on May 25, 2022 14:03:47 GMT -7
Your phone isn't anywhere close to the amp or guitar, is it? I wish it were that easy. First time I heard it, my phone was charging in the other room.
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Post by fishbeiner on May 25, 2022 15:00:00 GMT -7
Would that sound be indicative of a bad speaker? As that is the one variable I haven’t tried (due to lack of having another), I’m going to look into a new speaker.
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Post by purpletele on May 25, 2022 19:08:53 GMT -7
Based upon the sound and the previous CSI work that you have completed, I would guess that you have fouled resister somewhere in the circuit.
Just a hunch
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Post by fishbeiner on May 25, 2022 21:16:19 GMT -7
Based upon the sound and the previous CSI work that you have completed, I would guess that you have fouled resister somewhere in the circuit. Just a hunch There is nothing that immediately jumps out at me visually on the board. What is the process for troubleshooting something like that?
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Post by purpletele on May 26, 2022 7:16:22 GMT -7
Based upon the sound and the previous CSI work that you have completed, I would guess that you have fouled resister somewhere in the circuit. Just a hunch There is nothing that immediately jumps out at me visually on the board. What is the process for troubleshooting something like that? Looks pristine!! No signs of discolored resistor, It was worth a look. Might need some loving touch.
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Post by ME on May 26, 2022 7:27:28 GMT -7
I’d try another speaker. Just to eliminate that option. Do you have another guitar to try? Might be a cause… ME
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Post by fishbeiner on May 26, 2022 8:23:52 GMT -7
I’d try another speaker. Just to eliminate that option. Do you have another guitar to try? Might be a cause… ME I’m looking into the speaker issue today and will go from there. I do have some behind the scenes support now as well. Will fill in here as I go through the steps. Thank you!!
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Post by fishbeiner on May 29, 2022 15:20:03 GMT -7
For anyone following along, I tried another speaker, but it was a different type and much higher efficiency. I could still hear the noise, but it was not as prominent. Not sure if efficiency would affect the sound if it is an electronic issue.
Picked up another Creamback today so I can compare apples to apples. This way I will know for sure whether it is speaker or amp related.
Will follow up after I have a chance to test it out.
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Post by Don A on May 29, 2022 16:41:05 GMT -7
In your video, this seems to happen more when a couple of notes are played at once rather than single notes. Does it seem to happen more with certain intervals and at certain frequencies?
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Post by fishbeiner on May 29, 2022 17:26:04 GMT -7
In your video, this seems to happen more when a couple of notes are played at once rather than single notes. Does it seem to happen more with certain intervals and at certain frequencies? It’s definitely more noticeable when notes are played on the low E and A string (standard tuning). Higher pitched strings don’t seem to create any of that sound. Once I get back home this evening I’ll be able to see how the other Creamback reacts. I think that will be the biggest lead in where to look next.
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Post by purpletele on May 29, 2022 19:13:46 GMT -7
A few years ago, I went bonkers trying to find what was causing distortion on my AB763 Amp that I built. I replaced all of the components that could be suspect, it was irrational.
I had quite a few folks helping me on-line, I later noticed the handle cap, similar to a Z handle, was a bit loose.
Well guess what, that rattle was coming through my ears as distortion created by the speaker rumble. It was actually a secondary instrument creating a sound at a certain frequency.
I tightened the grip on the cap and the noise went away. I felt pretty silly to have rebuilt my amp based on a noise that was external and independent to my speaker.
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Post by Chilly Gibbons (Todd T.) on May 29, 2022 19:36:45 GMT -7
Yes, as Brian said - tighten up everything you can get a screwdriver or wrench onto.
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Post by adam on May 29, 2022 20:20:45 GMT -7
A few years ago, I went bonkers trying to find what was causing distortion on my AB763 Amp that I built. I replaced all of the components that could be suspect, it was irrational. I had quite a few folks helping me on-line, I later noticed the handle cap, similar to a Z handle, was a bit loose. Well guess what, that rattle was coming through my ears as distortion created by the speaker rumble. It was actually a secondary instrument creating a sound at a certain frequency. I tightened the grip on the cap and the noise went away. I felt pretty silly to have rebuilt my amp based on a noise that was external and independent to my speaker. I had something like that a while ago and thought it was a cab rattling. Turned out to be a piece of copper pipe I had laying in the ceiling. I had a hard time locating where that sound was coming from.
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Post by fishbeiner on May 31, 2022 19:01:37 GMT -7
Here’s another update.
Tried another Creamback and it’s the same thing. I can actually all the way to the G string. Could be my perception is off, but it seems to be slightly more prominent on the neck pickup.
As far as ambient noise, it is 100% coming through the speaker. Tested speaker in another room, same deal. Tried the speakers outside of the cab, same. Brought all of my gear to a friends house, same thing there. Tried a couple of his guitars, same deal.
Unfortunately I don’t have a third EF86 to swap in. I do have subs for the others and tried replacing each one, powering on and off after each. No real change.
Tightened the grounds, input jacks, and tapped around inside to see if anything jumped out. No go.
While going through all of this there were a few observations I made.
First, the sound I’m hearing is in addition to the note that’s actually being played. It is almost as if you can hear it underneath the one that’s being played.
Second, there’s something I noticed with almost every tube amp I’ve played. When you power off the amp there is this fizzy break up that swells, then gets quiet as the amp power is down. If you were to strum your guitar while the amp was powering off you can hear that fizzy distortion through the speaker. It sounds similar to the issue I’m having. Might not be related, but it was something that was interesting to me.
Lastly, as I was looking at some things on the Internet, I found one video that talks about faulty filter caps and “ghost notes“. The ghost notes demonstrated sounded very similar to what I am experiencing. Nowhere near as prominent, but that was the closest thing I could relate the sound to. I am not, however, experiencing any hum, at least that I can perceive.
If this is a filter cap issue, I don’t know whether I would be experiencing any hum with this (small compared to what is demonstrated in the video) level of leakage. Of course this is all speculation on my part. I don’t know if filter cap leakage is a longer process, or if it is immediate like an on/off switch.
I’ll wait to hear back from Don at Z-HQ has to say. Will relay any info here.
Filter cap/ghost note video:
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Post by purpletele on May 31, 2022 21:24:59 GMT -7
Here’s another update. Tried another Creamback and it’s the same thing. I can actually all the way to the G string. Could be my perception is off, but it seems to be slightly more prominent on the neck pickup. As far as ambient noise, it is 100% coming through the speaker. Tested speaker in another room, same deal. Tried the speakers outside of the cab, same. Brought all of my gear to a friends house, same thing there. Tried a couple of his guitars, same deal. Unfortunately I don’t have a third EF86 to swap in. I do have subs for the others and tried replacing each one, powering on and off after each. No real change. Tightened the grounds, input jacks, and tapped around inside to see if anything jumped out. No go. While going through all of this there were a few observations I made. First, the sound I’m hearing is in addition to the note that’s actually being played. It is almost as if you can hear it underneath the one that’s being played. Second, there’s something I noticed with almost every tube amp I’ve played. When you power off the amp there is this fizzy break up that swells, then gets quiet as the amp power is down. If you were to strum your guitar while the amp was powering off you can hear that fizzy distortion through the speaker. It sounds similar to the issue I’m having. Might not be related, but it was something that was interesting to me. Lastly, as I was looking at some things on the Internet, I found one video that talks about faulty filter caps and “ghost notes“. The ghost notes demonstrated sounded very similar to what I am experiencing. Nowhere near as prominent, but that was the closest thing I could relate the sound to. I am not, however, experiencing any hum, at least that I can perceive. If this is a filter cap issue, I don’t know whether I would be experiencing any hum with this (small compared to what is demonstrated in the video) level of leakage. Of course this is all speculation on my part. I don’t know if filter cap leakage is a longer process, or if it is immediate like an on/off switch. I’ll wait to hear back from Don at Z-HQ has to say. Will relay any info here. Checking the filter caps would be my next adventure. The two in the power section certainly do not look disfigured. I think you will have to check the caps with an Oscilloscope to get the best testing results. That circuit is so simple, and the caps are the next item on the list that might cause that noise and ghosting notes, I would say you are on to something. That would be fun to see you pin point it. What's your next move?
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Post by fishbeiner on May 31, 2022 22:10:19 GMT -7
As much as I don’t want to be ampless, I’m figuring it will be heading in to the Z shop to be looked over. I replied to Don, so I’m awaiting his response and advice. I’m sure he will suggest the same. If it does go, maybe I will see if they can replicate the “fire breather” updates from the M12 Doc sold on the BST a couple years ago (I think Todd ended up with that one). That, or, I’d be open to any possible new tweaks (if there are any). Either of those would be worth it!
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Post by fishbeiner on Jun 13, 2022 11:20:36 GMT -7
So… after a lot of testing, recordings, and correspondence with Don over at Z HQ, we have come to the conclusion that what I am experiencing is normal and expected behavior of the amp.
The sound I am hearing is resultant from the high output of the pickups (14.5k) I have in my guitar in conjunction with utilizing the “Hi” input of the M12. The “fizz” I was hearing is easily eliminated by switching to the “Lo” setting.
I feel a bit silly in creating a big deal out of this, but I am glad to have come to a resolve. Not only that, but I learned a bit about my amp, and how it’s design allows for the accommodation of a variety of guitars.
Many thanks to Don at the Dr. Z shop for all of his time and assistance. His decorum throughout has been top shelf. He even made me feel better with the “silly” feeling in honoring my observations. Thank you again, Don.
Calling it case closed and time to move on.
Thanks!!
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Post by "Z" Steve on Jun 13, 2022 11:42:09 GMT -7
These are the types of questions that, though it may end up as a "silly" thing, it will help with answering future questions re a "weird noise" in my amp. It also proves once again how great a team there is in Maple Heights, OH.
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Post by loucardguitar (Johnathan) on Jun 13, 2022 16:00:05 GMT -7
I know it's cliche, but there's no such thing as a silly question. It was important to you at the time and at least you were able to get it figured out and learned more about your amp!
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Post by purpletele on Jun 13, 2022 17:19:45 GMT -7
We'll that's interesting. I'm glad it worked out, and I learned something new.
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Post by detuned on Jun 14, 2022 12:42:38 GMT -7
I tightened the grip on the cap and the noise went away. I felt pretty silly to have rebuilt my amp based on a noise that was external and independent to my speaker. I had something like that a while ago and thought it was a cab rattling. Turned out to be a piece of copper pipe I had laying in the ceiling. I had a hard time locating where that sound was coming from. Was the pipe buffered or true bypass?
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