Transformer on preamp buzzing a little (dammit)

[spwal]

Hi,

Any idea what may have caused this? More importantly, possible remedies? This was a professionaly upgraded unit by the developer of the preamp. The preamp has been astounding and given me no issues and endless pleasure thus far. Now its got a little buzzing noise, and when hooked up to the speakers, im getting alot more wooshing noise than ususal (you always hear some hiss if you put your ear up to itbecause of the sensitivity of the speakers i think). Needless to say, i took it out of my system and can run digital volume control luckily.

So any ideas before I go to my local audio service store? Is a transformer something I want to fix myself lol? I can see where it goes to, its all soldered in. I would love to be able to do it myself....

Please tell me its like a bad fuse or something!

:blink:

[Baron030]

Hi Spwal

You say your preamp is buzzing a little. Is this an electrical noise that is being transmitted through your system and is coming out the speakers? Or is the buzzing a physical noise coming from the transformer itself?

Generally speaking transformers don’t go bad over time. What is most likely the source of your problem is a power supply electrolytic capacitor failing. Older electrolytic capacitors can develop internal shorts, which can lead to increased current loads on the power supply transformer. And I have even seen some older electrolytic caps explode.

If you have a little electronics background and possibly a VOM or Digital Multi-meter, it might not be that big a deal to isolate the problem and fix it yourself. One of the big challenges in any repair is finding exact replacement parts. One parts source that I can recommend is mouser electronics (www.mouser.com (http://www.mouser.com)).

Baron030

[Cyclotronguy]

If you are talking about mechanical noise from the transformer; keep in mind that transformers are very apt to make noise if they are receiving even a fraction of a volt DC along with the AC.

That little bit of DC, saturates the core and makes for an assymetrical current draw.

The offending device that's putting dc on your line is most likely a triac circuit used for a speed control on fans, lamp dimmer or etc.

If you have underground utilities the elec company usuall puts a small bit of dc on the system for galvanic protection... but applies DC blocking before it gets to you. Very very infrequently this fails.

Cyclotronguy

[boputnam]

This was a professionaly upgraded unit by the developer of the preamp. ... Now its got a little buzzing noise, and when hooked up to the speakers, im getting alot more wooshing noise than ususal...I'd recommend talking to whomever "professionally upgraded" the unit, whatever that means.

In this particular case, it means new "buzzing" and a lot more "wooshing" (I totally don't know what that is, but I want it... ;) ).

.

[JBL 4645]

I often use a piece of wire attached to the amplifier ground connection and attach to other audio electronics in the sound system chain. Most times it cures the problem its more trial and error most times in lactating the source of the problem.

[spwal]

Hi guys,

this preamp was profesionally upgraded by the actual inventor of the circuit. the actual engineer who created the Melos SHA1. All the caps look new, the upgrades were done this year. It was kind of a 3 time thing-- he modded/upgraded 3 or 4 units then went back to other pursuits. doubtful he would be interested in looking at it. plus hes in colorado i think.

the buzz is coming from the transformer itself. i have always heard a tiniest bit of noise coming from the drivers when i put my ear up close. Now the sound of "shhhhhhh" is more noticable, even with the volume all the way down. My spidey senses told me not to f with it and just hop on here asap to ask opinions.

this is a nice torroid, about the size of a krispykreme donut. cant see a value on it, its clear wrapped and not labeled on the top.

Buzz is still there today...

Do you think a power conditioner would do something? I doubt it, but I will try it heh.

If its still there after i come back from the mall with a power conditioner to try, i will just bring it in to the tech. hes gonna rake me over the coals for a repair bill. 50 bucks for a diagnosis, then long, drawn out hours after that.

sigh....

thank you all, still entertaining 11th hour suggestions....

[jblbgw_man]

Hi guys,

this preamp was profesionally upgraded by the actual inventor of the circuit. the actual engineer who created the Melos SHA1. All the caps look new, the upgrades were done this year. It was kind of a 3 time thing-- he modded/upgraded 3 or 4 units then went back to other pursuits. doubtful he would be interested in looking at it. plus hes in colorado i think.

the buzz is coming from the transformer itself. i have always heard a tiniest bit of noise coming from the drivers when i put my ear up close. Now the sound of "shhhhhhh" is more noticable, even with the volume all the way down. My spidey senses told me not to f with it and just hop on here asap to ask opinions.

this is a nice torroid, about the size of a krispykreme donut. cant see a value on it, its clear wrapped and not labeled on the top.

Buzz is still there today...

Do you think a power conditioner would do something? I doubt it, but I will try it heh.

If its still there after i come back from the mall with a power conditioner to try, i will just bring it in to the tech. hes gonna rake me over the coals for a repair bill. 50 bucks for a diagnosis, then long, drawn out hours after that.

sigh....

thank you all, still entertaining 11th hour suggestions....

If it's a torroidal then it is very very uncommon for the buzzing to be "mechanical" (as in loose windings) sounds like there is a fair load being drawn from the output, either crook filtering caps, crook bridge rectifier or the toroidal is under rated and running on it's limits. Presumably it is bolted down tight to the chassis? Try a larger VA rated troroidal .... good luck!

[boputnam]

...the buzz is coming from the transformer itself...

Egads... :blink: :bs:


...sounds like there is a fair load being drawn from the output, either crook filtering caps, crook bridge rectifier or the toroidal is under rated and running on it's limits. Agreed. I'd find the maker and ask him directly. Google him or something. Use your old contact info and find him. This would be something he'd be concerned about! :yes:

[JBL 4645]

Okay let’s try the re-mix version now shall we. Undone that is turn the power off to the preamp and open it up and then power it back up, once it looks okay. Use caution when looking around we don’t what any fatalities on the site now.

See if the transformer is screwed down securely that may or may not be what is cursing the buzzing humming, what ever have a look and see if you can’t locate the problem, because I have one out of two Alesis RA300 and one makes humming sound and I know for sure it’s the transformer, I’ve applied pressure on the chassis by pressing down on top of it and what would you know the humming minimizes.

Once pressure is realised, you guessed it, it comes back. I’ve undone the amplifier looked around even tightened up screws but it’s the whole assembly, its ether a bad batch or it needs modifying to a little bit of attention to correct it and make it sound, like the other RA300.

[SMKSoundPro]

Why does the transformer buzz and hum?













Because it doesn't know the words!

Scotty.

[JBL 4645]

Why does the transformer buzz and hum?



Because it doesn't know the words!



Scotty.


http://entertainment.timesonline.co.uk/multimedia/archive/00191/tran385_191475a.jpg

I didn’t understand a signal word those Transformers where saying it was all mumbling, mumbo jumbo, humming, buzzing, gibberish.:rotfl:

[Oldmics]

Loose center tap

On conventional designs I have been able to recrimp the tap.

Never had a turdroid apart so I dont know what to suggest except a possible transformer sacrifice and see if you can fix it.

Oldmics

[spwal]

thank you for the suggestion oldmic

[Russellc]

Hi Spwal

You say your preamp is buzzing a little. Is this an electrical noise that is being transmitted through your system and is coming out the speakers? Or is the buzzing a physical noise coming from the transformer itself?

Generally speaking transformers don’t go bad over time. What is most likely the source of your problem is a power supply electrolytic capacitor failing. Older electrolytic capacitors can develop internal shorts, which can lead to increased current loads on the power supply transformer. And I have even seen some older electrolytic caps explode.

If you have a little electronics background and possibly a VOM or Digital Multi-meter, it might not be that big a deal to isolate the problem and fix it yourself. One of the big challenges in any repair is finding exact replacement parts. One parts source that I can recommend is mouser electronics (www.mouser.com (http://www.mouser.com)).

Baron030
It is unusual, but I had it happen on a transformer that was the left channel heater circuit of my 6550 P-P amp. the transformer itself was humming, and the heater circuit in that channel measured slightly low. I changed out the heater supply caps, same problem. I then changed out the rectifiers, no help. then I changer out the 6.3 volt transformer itself, problem solved. turned out the transformer was internally shorted! Very unusual. but possible. You could definately isolate the problem yourself for no more than a few supply caps and or rectifiers, then transformer if it comes to that. Good learning project.

russellc

[greyhound]

did you move your pre amp prior to the problem. amps can hum when they are to close togheter.

did you check the interconnects. maybe they are short cirquiting a bit