Sonzera 20 has become noisy

Wakester

Re Member
Joined
Jan 2, 2018
Messages
4,425
Location
south western New York
Good aftermorning amplified officianado's.

I have started to notice my Sonzera 20 is becoming more and more noisy on the clean channel. The noise is a 60 cycle hum combined with the crackle of an open spark somewhere nearby. The dirty side sounds as it should with only a slight background hiss.

I re-tubed this amp shortly after getting it, and it was perfectly fine until recently when I thought about trading it in for a newer head and cab set. The store I took it to said it was too noisy and it may be the tubes and or re-bias. So, I ordered all new tubes and re-tubed it again. No change, the clean side still has the humbuzz and there was no change to the otherside either. I checked the bias and dropped it from 38 to 30.5 between the 2 sides.

Now I am stuck, because I really only have room for 1 amp in my office, and need the Sonzera to be 100% to either keep it or trade it.

Any thoughts or advice as to what could be causing the noisy channel, and how to fix it?
 
Good aftermorning amplified officianado's.

I have started to notice my Sonzera 20 is becoming more and more noisy on the clean channel. The noise is a 60 cycle hum combined with the crackle of an open spark somewhere nearby. The dirty side sounds as it should with only a slight background hiss.

I re-tubed this amp shortly after getting it, and it was perfectly fine until recently when I thought about trading it in for a newer head and cab set. The store I took it to said it was too noisy and it may be the tubes and or re-bias. So, I ordered all new tubes and re-tubed it again. No change, the clean side still has the humbuzz and there was no change to the otherside either. I checked the bias and dropped it from 38 to 30.5 between the 2 sides.

Now I am stuck, because I really only have room for 1 amp in my office, and need the Sonzera to be 100% to either keep it or trade it.

Any thoughts or advice as to what could be causing the noisy channel, and how to fix it?
Is it no longer under warranty?
 
Geez, that's a drag!

I'd try to find a reputable repair shop. Seems worth fixing, if it's not prohibitively expensive. They're nice amps.
I was really hoping to not have to dump a bunch of money into it. I mean I paid 425 for it and put 280 worth of tubes in it. I am going to guess a good amp shop is going to cost me that 280 again. So basically I am paying for the amp twice.

Would I just be better off putting it in the closet and saving up my travel and bonus checks until I can afford a new one?
 
I was really hoping to not have to dump a bunch of money into it. I mean I paid 425 for it and put 280 worth of tubes in it. I am going to guess a good amp shop is going to cost me that 280 again. So basically I am paying for the amp twice.

Would I just be better off putting it in the closet and saving up my travel and bonus checks until I can afford a new one?
It'd be a close call, given what you've already sunk into it vs the used value if you fixed it.

If you love the amp, it makes sense to fix. If it isn't your ultimate amp tone, probably not.

I always need super-dependable, bulletproof studio gear. I'd pay to fix any of my amps, but they were expensive. Fixing them would be more sensible than replacing them.

If I wasn't going to fix it, I'd pull the tubes and save them. Extra tubes always come in handy. At least that 280 won't go to waste!
 
In hind site, I am not in love with this amp, so I will probably be better off stripping it and moving on as you suggest. I've always owned Soild State Amps, until this one. I bought it because, why else but, it was the fanboy thing to do.

What I want is an amp that is dead quiet when on, not a modeling amp, preferably 2 channel, it needs to take pedals well. Other than that, I am not picky. I have considered amps by Orange, Blackstar and the HDRX 20 and cab.
 
In hind site, I am not in love with this amp, so I will probably be better off stripping it and moving on as you suggest. I've always owned Soild State Amps, until this one. I bought it because, why else but, it was the fanboy thing to do.

What I want is an amp that is dead quiet when on, not a modeling amp, preferably 2 channel, it needs to take pedals well. Other than that, I am not picky. I have considered amps by Orange, Blackstar and the HDRX 20 and cab.
My entire rig is dead silent when on until I hit a note. Have two of the US-made PRS amps, and two Mesas. I can have all four of them on, close-miked with good condenser microphones, and there's zero noise (I have an amp switcher).

I am picky about the tubes I use, but I find that the main culprit causing amp noise is signal ground loops. Modern, quality tube gear has solved the noise problems of yesteryear with careful attention to grounding, better parts selection, etc. But most folks don't understand what causes signal grounding problems using ancillary gear like pedals, or noise problems from wall warts, etc., so the amps get blamed.

Let's face it, regardless of cost, your tube amp should have been able to operate without much maintenance, not just for a few years, but for generations! How many amps from the '50s and '60s are still around, kicking out the jams? Lots of 'em!

And while they were wired by hand, it's not like the wiring was done lovingly by one or two people in a shop, testing each part carefully, using silver solder and unobtainium parts. They were slapped together like anything else in a factory! But at least for the most part they were made with something approaching quality and longevity.

That your amp and others couldn't is the operational problem with a lot of China-made goods. You can have excellent design by people like Doug Sewell, but if he's not in charge of its manufacture, all bets are off.

The old-time expression, 'you get what you pay for' is really true. People expect their inexpensive consumer TVs and electronics to be useful for a short time, and then wind up in the dumpster, so now all of that stuff comes from overseas except maybe high-end hi-fi gear.

I just can't get into Chinese musical gear, no matter whose name and logo are slapped on it. And now I see some of the PRS stuff, lots of the other brands, etc., being made in China (all Blackstar stuff is), and it makes me queasy. There's very little financial incentive for folks to make gear here, except for the boutique stuff, and that's a tiny market compared to the overwhelming sales of Chinese goods.

My son tours the world with an early 15-20 year old silver panel Mesa Lone Star that he bought used - in fact, he bought it a decade ago from one of the guys in the band he's touring with now, who still uses his other one! The damn things just chug along. These amps have done hundreds and hundreds of gigs over the years without problems, and have been carted and shipped everywhere.

They aren't hand wired, and not being an expert, I can't tell you what makes them better, or why the pros can depend on them, but fact is, they last and can be trusted like the old ones. I think it's the build quality and the fact that few corners need to be shaved to save ten cents here, and a quarter there to keep the product cheap.

I suppose I should end my rant now before I cause more trouble! ;)
 
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My entire rig is dead silent when on until I hit a note. Have two of the US-made PRS amps, and two Mesas. I can have all four of them on, close-miked with good condenser microphones, and there's zero noise (I have an amp switcher).

I am picky about the tubes I use, but I find that the main culprit causing amp noise is signal ground loops. Modern, quality tube gear has solved the noise problems of yesteryear with careful attention to grounding, better parts selection, etc. But most folks don't understand what causes signal grounding problems using ancillary gear like pedals, or noise problems from wall warts, etc., so the amps get blamed.

Let's face it, regardless of cost, your tube amp should have been able to operate without much maintenance, not just for a few years, but for generations! How many amps from the '50s and '60s are still around, kicking out the jams? Lots of 'em!

And while they were wired by hand, it's not like the wiring was done lovingly by one or two people in a shop, testing each part carefully, using silver solder and unobtainium parts. They were slapped together like anything else in a factory! But at least for the most part they were made with something approaching quality and longevity.

That your amp and others couldn't is the operational problem with a lot of China-made goods. You can have excellent design by people like Doug Sewell, but if he's not in charge of its manufacture, all bets are off.

The old-time expression, 'you get what you pay for' is really true. People expect their inexpensive consumer TVs and electronics to be useful for a short time, and then wind up in the dumpster, so now all of that stuff comes from overseas except maybe high-end hi-fi gear.

I just can't get into Chinese musical gear, no matter whose name and logo are slapped on it. And now I see some of the PRS stuff, lots of the other brands, etc., being made in China (all Blackstar stuff is), and it makes me queasy. There's very little financial incentive for folks to make gear here, except for the boutique stuff, and that's a tiny market compared to the overwhelming sales of Chinese goods.

My son tours the world with an early 15-20 year old silver panel Mesa Lone Star that he bought used - in fact, he bought it a decade ago from one of the guys in the band he's touring with now, who still uses his other one! The damn things just chug along. These amps have done hundreds and hundreds of gigs over the years without problems, and have been carted and shipped everywhere.

They aren't hand wired, and not being an expert, I can't tell you what makes them better, or why the pros can depend on them, but fact is, they last and can be trusted like the old ones. I think it's the build quality and the fact that few corners need to be shaved to save ten cents here, and a quarter there to keep the product cheap.

I suppose I should end my rant now before I cause more trouble! ;)
It's all good information, thank you Sir.
 
Could be an internal component on the circuit board, such as a resistor, bad solid state rectifier, bad solder job, etc. Send a video to Doug Sewell, the amp designer & state how you've attempted to remedy it. I was going to say replace the effects loop tube with a 12AU7, as that fixes most noisy loops, but yours sounds like circuit board related. Do you know a good amp repair shop you trust?
 
Could be an internal component on the circuit board, such as a resistor, bad solid state rectifier, bad solder job, etc. Send a video to Doug Sewell, the amp designer & state how you've attempted to remedy it. I was going to say replace the effects loop tube with a 12AU7, as that fixes most noisy loops, but yours sounds like circuit board related. Do you know a good amp repair shop you trust?
I am going to go with something on the board is going. Possibly a transformer. I've never had to take an amp in anywhere so I really don't know where to start looking. I have a few friends with connections, I will reach out to them.
 
I am going to go with something on the board is going. Possibly a transformer. I've never had to take an amp in anywhere so I really don't know where to start looking. I have a few friends with connections, I will reach out to them.
I repaired a Fender Concert recently, that went totally silent after an event like this... upon inspection of the board, all 3 rectifier circuits were blown. I'm betting the gentleman plugged it into an unregulated power supply & got a surprise. Once that & a couple other components had been replaced, the vibrato channel on that amp was totally gorgeous! My money is on the board, but those are also some symptoms of a failing transformer. Let me know which one it pans out to be...
 
Update on this, I finally un-busied myself enought to try trouble shooting this deeper with PTC. After about 5 emails changing one tube 12 times and a video attachment, the techs believe I have a rectifier diode going.

They are going to take the Amp in and repair it under warranty. I was given a RM# and a FedEx label to ship it down to Stevensville. I just have to wait until after the first of the year to send it.

Now to just find a box big and sturdy enough to send it in.
 
Update on this, I finally un-busied myself enought to try trouble shooting this deeper with PTC. After about 5 emails changing one tube 12 times and a video attachment, the techs believe I have a rectifier diode going.

They are going to take the Amp in and repair it under warranty. I was given a RM# and a FedEx label to ship it down to Stevensville. I just have to wait until after the first of the year to send it.

Now to just find a box big and sturdy enough to send it in.

See PRS CS, outstanding.
 
The Sonzera is back in my office where it belongs. I am absolutely astounded that this is the same amp that I sent out. It is absolutely quiet sitting there turned on and off standby, not even a hiss. It sounds so much better than it did, even better than when I bought it. Everything is very clear and as it should be. A big shout out to Matt in Customer Support and Jack in Tech who did the work. I am very happy with this Amp now.
 
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