What makes Sowter or Carnhill etc. transformers better technically?

[alisomay]

Interesting topic.
As someone who as never worked with transformers and is starting to build some preamps, i was wondering how the OEP are comparing to the other ones you guys mentioned ? i like those prices but maybe it's not worth it.. just wondering

I am wondering also, fortunately i will try soon i guess.
What do you plan to build??

 

[abbey road d enfer]

Interesting topic.
As someone who as never worked with transformers and is starting to build some preamps, i was wondering how the OEP are comparing to the other ones you guys mentioned ? i like those prices but maybe it's not worth it.. just wondering

At the risk of seeming pretentious, I think I was a little responsible for the arrival of OEP in the field of audio. In the 90s, my company created a subsidiary in United Kingdom, in order to manufacture products designed in France to benefit from a lower price of labor and components. OEP became our main supplier for (non-toroid) power transformers. Considering the excellent price of their products,  I asked them to duplicate the quadfilar transformer I had designed earlier and used intensively.
When the group that bought my company decided not to devote itself to construction any more, but only to trading, OEP felt, justifiably, that they were no longer bound and decided to market this product.
It is not to put myself forward that I write this, it is to show that there is an interest in using alternative resources, on the condition of mastering the theoretical aspects of a subject.

 

[ruffrecords]

I am wondering also, fortunately i will try soon i guess.
What do you plan to build??

You probably know that OEP are now owned by the Carnhill Group. Not sure what that means for OEP.

Anyway, as a rule you gets what you pays for.  Most transformer manufacturers are rather vague about their sepcs. The bass response depends on your source impedance and the inductance of the primary winding. Top end depends on leakage inductance and inter-winding capacitance. Distortion depends on core size and core material as others have already mentioned.

If you compare the size of many OEP input transformers with those from Carnhill, Jensen, Cinemag and Sowter of the same type, you will find the OEP ones tend to be smaller. If you compare the primary inductance of these transformers you will find it is also lower. SO they often have smaller cores and fewer turns both of which save money but bass response and distortion will suffer.

However, OEP do have some good transformers. I have recently been comparing several different 10K:10K transformers of theirs in an attempt to find a lower cost good quality line input transformer.. To give OEP their due, I asked them for specific parameters of these transformers and they have been able to provide most of them. They have offered to measure any that are missing.

The transformers I am looking at are:

A187A13C which costs £25

K30A06C which costs £40

Z21807C which costs £15?? (£24)

Z3002E which costs £27 (£39.50)

The Z21807C price is  from Canford. When I asked OEP for a price they said it was £24 for 10 or more. I told OEP  about Canford  having three in stock at £15 and they recommended I buy them all quickly so I did. All the transformers have mu metal screens except the Z2003E but you can buy a mu metal screening can for it for £12.50 which makes its comparable price £39.50.

I have attached the table of additional data supplied to me by OEP which shows the core material, primary inductance, maximum operating level and low frequency high level distortion. As you will see, the best ones are the K30A06C and the Z3002E both of which cost about£40 and they also have cores that are much larger than the other two.

Cheers

Ian

 

[dasnevestheo]

nice infos, thanks a lot

 

[noulou]

Wow that's motivating! Thank you!
Would you advise any source books?

Chapter 5
http://www.tubebooks.org/Books/RDH4.pdf

 

[Moby]

As i stated in the subject, when audio and transformers are in the same subject i hear these two brands frequently.
I am not a novice in electronics nor an expert. I would love to hear as much technical info as possible, or you can point me to some sources.
What makes these transformers audio transformers and why are they trusted and chosen technically?

This is my first post in the community btw, all the best to everyone!

Generally the brands you mentioned are OK and their presence on market are for many years.  People choose them because price/quality. But some other brands are maybe better for specific project.  It really depends from personal taste-budget which brand you will choose.  For example, range of transformers I produce can be found from 50-350USD and all of them "works" somehow.  Core alloy,  heat treatment process, magnet wire, insulation, winding technique,  etc, makes them sound better or worse and of course  define production price.

 

[pucho812]

it's all in the details and materials used.

I have seen transformers and their asian knockoffs and while they look the same and the pinout is the same, they are far from the same. on a sonic level they do not compare.  On a quality level they are not as consistent.  over all it's night and day. But this could be said about any transformer company.

 

[Moby]

it's all in the details and materials used.

I have seen transformers and their asian knockoffs and while they look the same and the pinout is the same, they are far from the same. on a sonic level they do not compare.  On a quality level they are not as consistent.  over all it's night and day. But this could be said about any transformer company.

Materials Once, I gave a magnet wire made in China a chance  and whole batch went to trash.  Poor insulation, and probably dirty wire alloy.  I don't say that all the products from Asia are bad, but my experience was  like that.