Topic: M6 & Ni Testing

[edcorusa]

Just in case anyone is interested, I did some testing on two identical quad-filar matching transformers. One with M6 steel core and one with 80% nickel. I posted the results here.

 

[Marik]

Obviously, for the same inductance the 80%Ni will need much less turns, so it will have much lower capacitance, DCR (both, as a function of shorter wire length and use of thicker wire), losses, etc.

Best, M

 

[syn]

Thank you.

 

[burdij]

The results shown in these drawings are measured at a signal level of 1V. Of greater interest to builders of preamps and other line output devices, that would use transformer-based amplification (such as a typical API 312 circuit), would be the maximum amplitude tolerated by the various materials at which a level of 1% THD + noise would be reached. As stated incorrectly (I believe) in some other posts (not here), the Ni cores would saturate at a lower signal level. I would like to learn which POV is correct. Also, I think, the transformers need to be tested with a load of 600 Ohms (or the appropriate value for the design) and a source with the correct termination impedance.

Your work is a step in the right direction.

 

[leswatts]

Thanks for the data.

Question:

In very low level transformers (like microphone) is M6 vs nickel really that much of a cost issue? So little is used...

Les
L M Watts Technology

 

[edcorusa]

Obviously, for the same inductance the 80%Ni will need much less turns, so it will have much lower capacitance, DCR (both, as a function of shorter wire length and use of thicker wire), losses, etc.

That is right. For the same inductance you would drop the number of turn and increase the wire size, this will also help with increasing the VA (volt amps). This is why you design a transformer around the core you are using. The problem is that most ask for a high inductance rating. As the number of turns goes up then the size of the wire goes down to compensate the build-up of the wire on the bobbin. This lowers the VA rating of the transformer that causes a lower saturation level.

The results shown in these drawings are measured at a signal level of 1V. Of greater interest to builders of preamps and other line output devices, that would use transformer-based amplification (such as a typical API 312 circuit), would be the maximum amplitude tolerated by the various materials at which a level of 1% THD + noise would be reached. As stated incorrectly (I believe) in some other posts (not here), the Ni cores would saturate at a lower signal level. I would like to learn which POV is correct. Also, I think, the transformers need to be tested with a load of 600 Ohms (or the appropriate value for the design) and a source with the correct termination impedance.

I have the two transformers on my desk waiting for more testing. I am also looking into getting a few more wound up to test with cobalt, nickel/steel and nickel/cobalt cores. I am planning on testing with 10,000 and 600 Ohms loads and at higher voltages as well. My main idea was to test the different cores with the same coil design.

In very low level transformers (like microphone) is M6 vs nickel really that much of a cost issue? So little is used...

As for price between nickel and steel in smaller transformers, one has to also consider the manufacturing costs of the different core material, not just nickel costs more than the steel, about 4X more. Some of the other cost that must be taken into consideration is the cost of labor. Steel cores, like the M6, can be mostly stacked on stacking machines. Nickel, on the other hand cannot, because it is a softer metal and bends very easily. Extra care must also be taken when hand stacking nickel. 

 

[illacov]

So you are indeed going to look into the nickel/cobalt/steel cores?? This would definitely have an impact on your economical pricing don't ya think??

Or would these be in a special category??

Cinemags CM 2461 NiCo is nearly 100 dollars a piece. It is a nice transformer but not perfect for everything where you'd need that particular transformer and the cost is always a factor in that regard.

I wonder if you've found a good cheap source of cobalt steel?? Shoot me an email if so.

Thanks

Peace
Illumination aka Langston

 

[Marik]

Obviously, for the same inductance the 80%Ni will need much less turns, so it will have much lower capacitance, DCR (both, as a function of shorter wire length and use of thicker wire), losses, etc.

That is right. For the same inductance you would drop the number of turn and increase the wire size, this will also help with increasing the VA (volt amps). This is why you design a transformer around the core you are using. The problem is that most ask for a high inductance rating. As the number of turns goes up then the size of the wire goes down to compensate the build-up of the wire on the bobbin. This lowers the VA rating of the transformer that causes a lower saturation level.

Not sure why do we worry about VA and how the thinner wire causes lower saturation level in small signal transformers. Plenty of line level transformers wound with even as fine as #48 wire without any saturation problems.

Best, M

 

[mobyd]

Anyone know a quick'n'dirty "kitchen sink chemistry" test for nickel ?. Have a pile of lams that I'd like to assay. Thet are much softer and more shiney than M6.
Cheers
M

 

[abbey road d enfer]

Not sure why do we worry about VA and how the thinner wire causes lower saturation level in small signal transformers. Plenty of line level transformers wound with even as fine as #48 wire without any saturation problems.

Best, M

Obviously, VA rating is not important, but saturation is; more turns of thinner wire yields more inductance, hence less current and thus less A.t. But Ni has a very different saturation curve and when hitting high levels, it may distort more than M6.

 

[Moby]

Thanks Brian. 

 

[edcorusa]

So you are indeed going to look into the nickel/cobalt/steel cores?? This would definitely have an impact on your economical pricing don't ya think??

Or would these be in a special category??

Cinemags CM 2461 NiCo is nearly 100 dollars a piece. It is a nice transformer but not perfect for everything where you'd need that particular transformer and the cost is always a factor in that regard.

EDCOR is looking into differnet core materials mainly for testing. They are not sure if they are going to creat any new product lines with colbalt or nickel mixed cores. As for pricing, EDCOR's prices are based on labor, material and a reasonable profit. The price for colbalt is up there and may not warrant the cost of purchasing it.