r-core output transformers...

[smithie]

hi all
posted this on another forum and got no response,so im hoping some people here can share some views etc.
im using a 859 e.a.r clone amp,and im well happy with it,for output transformers its using r-core types and as ive noticed these type dont seem to be popular or even exisist much(only found one company on the web doing them,cant find the site for the the ones i have so i assume they dont make or trade anymore) iwas wondering if i could get a better leap in sound quality by replaceing them for more standard type affairs? it would of been nice to have got some original txs as specced by tim but i doubt ill ever come across apair of them so maybe some from sowter or the likes might bring the improved sound quality....or not,anyone got any views? im just going on the assumption that has r-cores as output txs havent taken off and almost died then that cant be good thing
as ive said,im enjoying the sound im getting,just wondering if theres more to be had,the other trouble is i dont know what spec they should be!
all the best
smithie

[45]

Originally Posted by smithie

hi all
posted this on another forum and got no response,so im hoping some people here can share some views etc.
im using a 859 e.a.r clone amp,and im well happy with it,for output transformers its using r-core types and as ive noticed these type dont seem to be popular or even exisist much(only found one company on the web doing them,cant find the site for the the ones i have so i assume they dont make or trade anymore) iwas wondering if i could get a better leap in sound quality by replaceing them for more standard type affairs? it would of been nice to have got some original txs as specced by tim but i doubt ill ever come across apair of them so maybe some from sowter or the likes might bring the improved sound quality....or not,anyone got any views? im just going on the assumption that has r-cores as output txs havent taken off and almost died then that cant be good thing
as ive said,im enjoying the sound im getting,just wondering if theres more to be had,the other trouble is i dont know what spec they should be!
all the best
smithie

Actually they appear to work and sound very well.
Maybe they are not so popular because you get lower inductance in comparison to Fe cores (of comparable size). This is more o less the same for other amorphous cores.
However they have a much smaller coercive field (near to zero) and tighter hysteresis loop that makes them more linear devices. In other words they have lower eddy currents losses and lower hysteresis loss. The permeability is higher and more costant (as function of the induction B) however when you place a gap for DC application it reduces to smaller values than those of a conventional core (i.e. same turns = less inductance).
They work very well with low impedance devices, like triodes, much less with pentodes.

Here is one manufacturer: Softone/ICL's AUDIO PRODUCTS
Very interesting is the interstage tranny.

Cheers,
45

[Bas Horneman]

The popularity or lack thereof of the R-cores has AFAIK nothing to do with the technical abilities of the R-core.

Therefore I think it is safe to say the you won't necessarily have better sound from say an EI core or whatever.

The primary of that output transformer should be around 1600 Ohm. And 150mA of current. Single Ended transformer ofcourse. Something like the One Electron UBT-1.

[45]

Originally Posted by Bas Horneman

The popularity or lack thereof of the R-cores has AFAIK nothing to do with the technical abilities of the R-core.

A 5K OPT with 12-14H only would be not suitable for pentode or ultralinear application. If you can get 50 Hz flat it's great result!
They are non for general use as other types....

[Bas Horneman]

A 5K OPT with 12-14H only would be not suitable for pentode or ultralinear application.
They are non for general use as other types....

I don't understand what you are trying to tell me or the original poster?

[45]

Originally Posted by Bas Horneman

I don't understand what you are trying to tell me or the original poster?

That they are not for general use in audio amps as the conventional cores. Especially because the majority of commercial amplifiers use pentodes in UL connection. If not so they would be more popular.....

[smithie]

hi guys
thanks for your responses and views.
as i said originally the 859 clone sounds good as is,i was just curious if i could ring more from it by upgrading the txs as they are a unknown to me compared to usual fair.
this amp uses el509 tubes in a triode fashion,although in my case im using el519 and should roughly be producing 13watts se.
its a shame the producer of the r-cores i have no longer seems to be around so i could get the true spec on the ones im using...the company was diy-audios.com
all the best and once again many thanks for the views and insight.
smithie

[richwalters]

I thought Lundahl uses R cores ?

richy

[Bas Horneman]

I thought Lundahl uses R cores ?

They use a C-core.

R-cores are mostly found in Asia for some reason.

[kavermei]

No, they use C-cores mostly.

Beat me to it, Bas!