Quality of Hammond 300 series power transformers compared to 200 series?

[G]

Hi All,

I've ordered a 300 series power transformer from Hammond for a ongoing project and I was wondering. Do the 300 series have the same mechanical hum problem that the 200 series have? Thanks.

G

[Colt45]

mechanical hum problem?


you sure you had it attached to your chassis properly?

[G]

I don't have it yet. I've heard about people having problems with mechanical hum from the 200 series. I was wondering if anyone had heard of or experienced a problem with the 300 series?

G

[Fuling]

My 6B4G SE amp has a Hammond 372-something in the PSU, and it does hum.

[Elkaid]

I'm experiencing quite the same with the 182 toroidal series... But only when one of my halogen lamp is turned on at about 50%. If it's fully on, the transformer won't hum a bit.

Maybe adding some kind of line filter would help but I haven't tried it yet.

I hope this helps !

[EC8010]

There's a long list of, "transformers don't like," and DC is top of the list. A lamp dimmer undoubtedly involves a switching triac, which shouldn't impose DC on the mains, but will certainly impose some nasty current pulses, and as these dimmers are always made for extreme cheapness, I wouldn't like to guarantee it can't impose DC. I've just had a horrible thought. That halogen lamp doesn't have a switch to set 50% does it? Because if it does, it achieves 50% by half-wave rectifying the mains, which is absolutely the worst imposition of DC!

Another point is that in terms of DC sensitivity, toroids are most sensitive, followed by C and R core, and lastly, EI.

[Elkaid]

I've just had a horrible thought. That halogen lamp doesn't have a switch to set 50% does it?

You're right, no dimmer. Only a 3 positions switch. 100%, 50% and OFF.

It took me some time to find out that my toroidal transformer didn't like my lamp.

Do you think that somekind of line filter would do the job ?

Thanks for your comments !

[EC8010]

Originally posted by Elkaid
Do you think that some kind of line filter would do the job?

I'm afraid not.

On parallel lines, I've recently been thinking about dimmers and decided that they are downright unpleasant things. Not only do they squirt RF everywhere, but they drastically reduce efficiency, so they waste energy. If you want to control the amount of light, it's far better to control the number of lights switched on. When I was little, prior to our house being rewired, one room had a central light fitting with three bulbs. Two bulbs were wired in parallel, and two circuits came back to the twin mains switch, giving three levels of brightness, all at the same colour temperature, and all at optimum efficiency. The next time the floors are up, those dimmers are going, and the superior 1930s technology of a trio of bulbs is going in...

Power control using a diode is an abomination and should be outlawed.

[mcs]

I have used two Hammond 300 series transformers and none of them hum. I use them with tube rectifiers and choke input filters though - they may hum with cap input supplies.

I have no experience with the 200 series for obvious reasons.

Best regards,

Mikkel C. Simonsen