[E55l2]

I only use c-cores, HiB (M0) or sometimes amorphous.

With 12K you use EI or C core?

[FullRangeMan]

I only use c-cores, HiB (M0) or sometimes amorphous.

Oh Nice. You have a site or price list?

[E55l2]

i normally make costume transformers but soon i will have a site where you can get information about the products i make/ made.

Soon will be a new batch of cores arrive, mostly amorphous and nano crystaline. If you have a request send me a pm.

Oh Nice. You have a site or price list?

[FullRangeMan]

I only use c-cores, HiB (M0) or sometimes amorphous.

Very interesting, what differences there is on M0 x M6 besides thickness?

[E55l2]

M0 and M6 are both available in 0,35; 0,3; 0,27; 0,23 and on request 0,1 mm or even thinner.
The difference is core loss. In general M0 has 50% lower core loss then M6.

In -EI more then C-  cores you can easily see the big impact of core loss if you measure the -3dB point at low frequencies at different output levels.
I have seen transformers have a drop from -3dB at 10Hz to -3dB 40Hz just by changing the output level (it's worse at lower level and worse for lower core quality)

Be aware that core loss is the more important for low frequencies because in an audio transformer induction get lower when the frequenciy rise.
For high frequencies in audio transformers the coil will do the job.

Very interesting, what differences there is on M0 x M6 besides thickness?

[FullRangeMan]

Thanks E55l2 this was very instructive.
Iam especially curious about the Mingda transformers, all reports say the sound on the big triodes amps are good even being EI.
They inform on its site the lamination are Z11 and H18-maybe OPT and Power.
What you would say to me to decrease my ignorance?
It is possible use Z11 and H18 on the same OPT??
The OPT is open:

[E55l2]

Technical speaking, yes you can mix core materials. It's can be done with EI, C-cores and toroids.

If you like warm not so detailed sound with max power of the core, go for an EI core, cheap and good enough for a lot of people.

If you like details go for c-cores and if you also like details on medium or low power levels (read magnetic flux) maybe amourph cores are better. Maybe because amourphous core have more problems with low frequencies/copper loss then c- cores because the maximum flux is limited.

btw a transformer for 2W amplifier can have high flux levels too. It's the flux what matters + the core weight (core loss is W/kg)

 

Thanks E55l2 this was very instructive.
Iam especially curious about the Mingda transformers, all reports say the sound on the big triodes amps are good even being EI.
They inform on its site the lamination are Z11 and H18-maybe OPT and Power.
What you would say to me to decrease my ignorance?
It is possible use Z11 and H18 on the same OPT??
The OPT is open:

[FullRangeMan]

Technical speaking, yes you can mix core materials. It's can be done with EI, C-cores and toroids.

If you like warm not so detailed sound with max power of the core, go for an EI core, cheap and good enough for a lot of people.

If you like details go for c-cores and if you also like details on medium or low power levels (read magnetic flux) maybe amourph cores are better. Maybe because amourphous core have more problems with low frequencies/copper loss then c- cores because the maximum flux is limited.

btw a transformer for 2W amplifier can have high flux levels too. It's the flux what matters + the core weight (core loss is W/kg)

Wow great post thanks.
Do you have comments about the Mingda OPTs?

[E55l2]

How can i if there is no data or measurements?

Wow great post thanks.
Do you have comments about the Mingda OPTs?

[FullRangeMan]

How can i if there is no data or measurements?

That picture does not fit to reverse engineering?

[E55l2]

If you like snake oil maybe, but i not like that kind of......

That picture does not fit to reverse engineering?

[FullRangeMan]

If you like snake oil maybe, but i not like that kind of......

But the photo I would say these OPTs from that factory use low priced parts as thick EI and copper wire.
So the secret of good sound may be the interleaving.

[E55l2]

Can't see how thick the laminations are. It's EI so not the best choice for quality transformers.

Copperwire is fine, Silver is for snobs. Remember the nickel, iron, aluminium, carbon, molybdeen and other materials where they make tubes/resistors/capacitors from.

Interleaving helps to make a good transformer but there are other techniques to improve a transformer.
If you want to know if it is a good transformer at least you need some simple measurements: frequency response at 1W measured from 1Hz-1Mhz preferable + a square wave 10KHz or 20kHz +copperlosses.

photo taken from : www.triodedick.com

At this picture you can see what the problem is. The frequency response looks good but the transformer has a lot ringing. If they did a square wave measurement at 10kHz you could see this really good.
The problem gets worse with real speaker loads.

But the photo I would say these OPTs from that factory use low priced parts as thick EI and copper wire.
So the secret of good sound may be the interleaving.

[FullRangeMan]

OK. Its post/after ringing or harmonics from the audio range.
I was unaware trafos also have this prob.
Thanks

[E55l2]

There is a reason that some transformers* are famous and there is also a reason that most companies don't give propper datasheets about there products.

* there are also famous brands but not all products they make are good. Check the facts!

Btw the picture i showed is actually not a bad transformer. I have seen much much worse (look at the  "test" from the ETF)

OK. Its post/after ringing or harmonics from the audio range.
I was unaware trafos also have this prob.
Thanks