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can too little distance between speaker magnet and transformer cause problems?

zzzezums

Gold Supporting Member
Messages
2,077
I have a Vibroking which has huge transformers. I changed one of the speakers and now there is only a guitar pick's clearance (not a thick V-pick!) between the Weber 10F150T and the transformer. It sounds great, but should I be worried?
Thanks.
 
Messages
1,657
If it sounds great, then it's not a problem.

There are vintage speakers out there (not specifically Field Coil) that actually have the output transformers mounted right on the speaker frame.

Transformers put off an electro-magnetic field and sometimes they can interfere with surrounding components. If you're familiar with hi-fi equipment, you might've noticed that power transformers and output transformers are usually mounted at 90 degree angles to each other due to the interference they can create.

Personally, I've seen transformers interfere with other components, but never had a problem with speakers.

Your ears are the judge. If the only sound you're hearing out of your amp is your guitar signal, then you're in fine shape.

If it's the power tranny that you're speaking of, and if yours gets rather hot, then it's conceivable that high heat may shorten the life the paper cone in the long term, but probably not.

If it were my amp, I wouldn't worry.
 

Silent Sound

Member
Messages
5,525
I would be worried about the magnet of the speaker magnetizing the transformer. That could be bad. But I guess since you've already done it and everything still sounds good, then it's probably okay. It's hard to say. I know a bit about electronics, but I'm far from an expert, and this might be one of those things where theory doesn't really equate to practice like you think it would.
 

drbob1

Gold Supporting Member
Messages
29,058
The tweed Bassman and Bandmaster have transformers that are almost touching the speakers and they've sounded find for 55 years now. Don't sweat it!
 

Diablo1

Member
Messages
620
I would be worried about the magnet of the speaker magnetizing the transformer. That could be bad.
The speaker magnet will never permanently magnetize the steel in the transformer laminations. Those lamination are made from grain oriented electrical steel, which is designed to be easily magnetized and demagnetized - it's called magnetically soft. Steel for a permanent magnet is a much different alloy, and is magnetically hard - difficult to magnetize and demagnetize.

If you place a speaker magnet close to your transformer, the magnet will induce a magnetic field on the transformer in one direction. This won't cause a hum or any noise in the output because it's not an alternating magnetic field. However, the transformer is now more easily magnetically saturated by the power amp current in that one direction. So, you could have some measurable difference in the output of the transformer under high volume / high current conditions which are close to magnetic saturation. So, close placement of the speakers to the OT is not desirable, but from a practical standpoint, lots of amps have been built that way and no one seems to notice the difference.
 

pdf64

Member
Messages
8,064
That's a great response!
I guess that the potential for magnetic saturation could be an issue for the power transformer also. If its magnetic circuit normally runs close to capacity at high loads, then the mag field of a speaker could skew it such that part of the wave enters saturation.
This may cause the transformer to draw more line current and run hotter.
Pete
 

Diablo1

Member
Messages
620
That's a great response!
I guess that the potential for magnetic saturation could be an issue for the power transformer also. If its magnetic circuit normally runs close to capacity at high loads, then the mag field of a speaker could skew it such that part of the wave enters saturation.
This may cause the transformer to draw more line current and run hotter.
Pete
Yes, the same thing applies to the PT if it runs close to saturation. I've thought about the concept of applying an external magnetic field to an output transformer so it would saturate magnetically, and reduce the efficiency to act like an attenuator. But then, some experienced folks convinced me that magnetic saturation of the OT sounds bad.
 






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