My eden wt300 has a bad case of trafo buzz, causing interference in the end stage of the amp. The buzz is coming through the speakers at an even, low volume and is independent of the pre-amp settings or whatever is plugged in. It's no big deal at a gig, but it's pretty irritating when practising at home. Using other wall sockets, etc. makes no difference at all. Any suggestions on how to fix this?
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
torroïdal trafo buzz
- Thread starter Matthijs
- Start date
Check the bridge rectifier and power supply filter capacitors. Even a loose connection could cause this. Also, check the grounding connections inside the amp.
But do it safely. You won't notice the trafo buzz in heaven.
But do it safely. You won't notice the trafo buzz in heaven.
My amp has a case of this I think too! I'm gonna take it to a tech and have him look at it, maybe you should too to be safe!!.And you are correct it is damn irritating!!
billfitzmaurice
Commercial User
- Sep 15, 2004
- 16,860
- 278
- 76
- Disclosures
- Owner, Bill Fitzmaurice Loudspeaker Design
It is definetely not a problem with the transformer. Transformer 'singing' is vibration in the windings, it is mechanical, not electrical, and cannot be heard through the speakers. Anything that can be heard through the speaker has an electrical source, which indicates either bad filter caps or a defective ground connection in the amp, if not an outright design fault.Matthijs said:
billfitzmaurice said:
+1
As such, you'd notice the noise even with no cabinet plugged into the head. I've heard some nice transformer hum upon taking my SVT-2 Pro out of standby, but it's only a transient condition. That's a big-ol' iron-core transformer too.
Definitely check out filter capacitors if you're qualified, along with the rest of Bill's advice.
In the hi-fi world they sell DC blockers that keep DC off the input to the power transformer to eliminate mechanical hum. For example:
[Invalid or Expired Link Removed]
About halfway down the page.
But I'd record the humming and contact the manufacturer, in this class of amp it shouldn't be a problem.
[Invalid or Expired Link Removed]
About halfway down the page.
But I'd record the humming and contact the manufacturer, in this class of amp it shouldn't be a problem.
billfitzmaurice
Commercial User
- Sep 15, 2004
- 16,860
- 278
- 76
- Disclosures
- Owner, Bill Fitzmaurice Loudspeaker Design
There is no DC present on AC power lines, and even if there were it could not induce hum.seamonkey said:
billfitzmaurice said:
It's pretty common to see this mentioned. See Plitron's page:
http://www.plitron.com/lono.asp
Bob Lee (QSC)
In case you missed it, I work for QSC Audio!
- Jul 3, 2001
- 12,668
- 2,036
- 67
- Disclosures
- Former Technical Communications Developer, QSC Audio
billfitzmaurice
Commercial User
- Sep 15, 2004
- 16,860
- 278
- 76
- Disclosures
- Owner, Bill Fitzmaurice Loudspeaker Design
If you want to hear what DC sounds like hook up a speaker to a nine volt battery. What you're listening to is a zero Hz tone.
BassIan said:
Actually, i can hear the transformer buzzing by itself. That's how I came to the conlusion the interference and the trafo were linked. I took Bill's advice, up to the limit's of my qualification's (which don't go very far) Could find no obvious bad contacts or unhealthy looking capacitors.
Did manage to limit the interference by a lot by turning the trafo half a turn. The buzz trough the speakers is now way less irritating.
About the DC in the AC thing. Google turned those links up for me too. I couldn't make any real sense out of them. I'm no techie, but I'm also not a dunce. Seems to me they're talking about some kind of a DC offset in the AC. I'd think that offset would have to be really big to cause the mechanics in the trafo to vibrate.
By the way. There are sevaral links on the Eden customer forum about this problem in wt amps. Seems to be not uncommon for Eden's to buzz because of the transformer. I asked the customer service about my problem. So far I've only recieved some friendly repeats, but no answers. "The tech department will get back to me"
By the way. There are sevaral links on the Eden customer forum about this problem in wt amps. Seems to be not uncommon for Eden's to buzz because of the transformer. I asked the customer service about my problem. So far I've only recieved some friendly repeats, but no answers. "The tech department will get back to me"
billfitzmaurice said:
The mains transformer in my Trace V4 'sings' to me like you say when it gets nice and hot. Is it dangerous and/or damaging to the amp, or is it just very very annoying?
billfitzmaurice
Commercial User
- Sep 15, 2004
- 16,860
- 278
- 76
- Disclosures
- Owner, Bill Fitzmaurice Loudspeaker Design
Just annoying. The transformer windings are literally vibrating, but even if those vibrations managed to somehow show up on the output of the transformer that output is rectified to half-wave AC and then filtered to DC, and DC by definition is noiseless. It is possible for transformer singing to vibrate the chassis and from there be amplified by microphonic tubes or capacitors, but that would be rare.DMX said:
On the otherhand, the transformer is a source of system noise. Transformers are transmitters of EMI, electro-magnetic interference, and electro-magnetic pickups are receivers. In most cases controlling EMI is mostly a matter of moving away from the amp(s).
seamonkey said:
Has anyone read the blurb on this "DC blocker" device? It's hilarious! It's a nice little earner for somebody, too: three components, which put together must be worth all of £2 ($4), slapped on a little PCB and retailed for around £20 including VAT. Neat!
In the Hi-Fi world they'll sell anything they can bamboozle their more-money-than-sense customers to pay silly prices for.
I myself do a very nice line in tinfoil hats, guaranteed to prevent the user's brainwaves from interfering with the rotational stability of his 200lb polished granite turntable. Essential kit for the serious audiophile and a bargain at only $2,000 each. (Please note: after 24 hours the hat becomes saturated with brainotronic energy particles, rendering it ineffective. Replacements available in packs of 5.)
Espidog said:Has anyone read the blurb on this "DC blocker" device? It's hilarious! It's a nice little earner for somebody, too: three components, which put together must be worth all of £2 ($4), slapped on a little PCB and retailed for around £20 including VAT. Neat!
In the Hi-Fi world they'll sell anything they can bamboozle their more-money-than-sense customers to pay silly prices for.
I myself do a very nice line in tinfoil hats, guaranteed to prevent the user's brainwaves from interfering with the rotational stability of his 200lb polished granite turntable. Essential kit for the serious audiophile and a bargain at only $2,000 each. (Please note: after 24 hours the hat becomes saturated with brainotronic energy particles, rendering it ineffective. Replacements available in packs of 5.)
The Lcaudio includes buss strips to hook up their amps with including a separate gate drive transformer.
And Lcaudio publishes the schematic on the same page so you can build your own if you''re so inclined. It's not more than a blocking cap. So don't get bamboozled by line conditioner companies that sell for hundreds of dollars.
Don't be too quick to dismiss this effect. Plitron, who are experts in the design and building of toroidal transformer mention it in a paper and in their product line.
xformer singing is common
i work with power supplies for vacuum pumps used on linear accelerators and for clean vacuum tube manufacturing
(hello eimac and svetlana)
our largest supply has an output of 1kW @ 1A when the pump is in glow discharge some xformers will sing, and they will vibrate until the pump takes off and then the hum is reduced
it does not have any effect on the gear it just sings
like the sirens trying to lure you toward them
but the noise can irritate and so it can cause you to chaffe
i work with power supplies for vacuum pumps used on linear accelerators and for clean vacuum tube manufacturing
(hello eimac and svetlana)
our largest supply has an output of 1kW @ 1A when the pump is in glow discharge some xformers will sing, and they will vibrate until the pump takes off and then the hum is reduced
it does not have any effect on the gear it just sings
like the sirens trying to lure you toward them
but the noise can irritate and so it can cause you to chaffe
As much as it pains me to say it, Seamonkey is right. 
Just kidding, it doesn't pain me, we just don't tend to agree very often...
There are DC components/offsets on a typical household AC line, typically cause by things like lighting dimmers and ballasts that inject a bunch of crap into the line. The resulting asymmetrical waveforms have a DC component. Stick a scope on a wall outlet and see how not sinusoidal the signal is.
Anyway, in a non-air gapped toroidal transformer, it doesn't take much DC current to saturate the core because of the high magnetic efficiency. Once the core is magnetically saturated, it's susceptible to magnetostriction. The magnetic field actually deforms the iron molecules in the core, which causes the core to vibrate. There are two cycles of this per cycle of AC, which is why transformers buzz at 120Hz (or 100Hz in places where line frequency is 50Hz). It takes very little DC (a few milliamps or less) to produce this effect in toroids.
Lots of manufacturers take steps to block DC current from passing through the primary winding of a power transformer. Including big respected ones like Bryston. You can build an effective DC blocker with a diode bridge and a couple of capacitors placed on the neutral side of the transformers primary. The caps pass the AC and the diodes block any DC on the line as long as the voltage is less than the forward drop of the diodes.
This is one of the few things in the audiophile world that isnt voodoo or snake oil.
Plitron makes some of the best transformers anywhere. We use 5 different custom Plitron toroids in our products. I was actually talking to their lead power transformer engineer today. Great company to deal with!
Just kidding, it doesn't pain me, we just don't tend to agree very often... There are DC components/offsets on a typical household AC line, typically cause by things like lighting dimmers and ballasts that inject a bunch of crap into the line. The resulting asymmetrical waveforms have a DC component. Stick a scope on a wall outlet and see how not sinusoidal the signal is.
Anyway, in a non-air gapped toroidal transformer, it doesn't take much DC current to saturate the core because of the high magnetic efficiency. Once the core is magnetically saturated, it's susceptible to magnetostriction. The magnetic field actually deforms the iron molecules in the core, which causes the core to vibrate. There are two cycles of this per cycle of AC, which is why transformers buzz at 120Hz (or 100Hz in places where line frequency is 50Hz). It takes very little DC (a few milliamps or less) to produce this effect in toroids.
Lots of manufacturers take steps to block DC current from passing through the primary winding of a power transformer. Including big respected ones like Bryston. You can build an effective DC blocker with a diode bridge and a couple of capacitors placed on the neutral side of the transformers primary. The caps pass the AC and the diodes block any DC on the line as long as the voltage is less than the forward drop of the diodes.
This is one of the few things in the audiophile world that isnt voodoo or snake oil.
Plitron makes some of the best transformers anywhere. We use 5 different custom Plitron toroids in our products. I was actually talking to their lead power transformer engineer today. Great company to deal with!
