FEELER: Moby´s T14/1 and C12A transformers reincarnations

[Moby]

Hey Srdjan,
your transformer sounds fantastic !
Replaced it with my AMI T14.
The AMI T14 ist also excellent, but to my ears your transformers sounds slightly „better“.
I really appreciate your work !

Dear TIIM, thanks a lot for the update.

 

[wave]

Mine arrived today! They are so beautiful!
Great job Srdjan and Milan.

 

[earlfsmith]

Got mine a few days ago. Looks great. Will try to fine time to finish another c12. Thinking about grabbing two more

 

[duantro]

My pair showed up today. Hope to install them tomorrow!

 

[Delta Sigma]

My pair made it to me in Canada!

 

[Vac11]

Great to hear that pacel was delivered in Canada!!! Thanks for letting me know.
It looks like there are only four non-delivered parcels (Italy, 2x Canada, USA). Guys pleas be patient!

 

[hitchhiker]

Great to hear that pacel was delivered in Canada!!! Thanks for letting me know.
It looks like there are only four non-delivered parcels (Italy, 2x Canada, USA). Guys pleas be patient!

Mine arrived yesterday, thanks guys!

 

[Moby]

Once more important note! Be sure that coupling caps in front of T14/1 are not leaky and be sure that you dont put any DC on primary side (blue blue leads). It means even measuring the resistance of the primary (it's around 3kohms) because primary side is winded with the ultra thin wire what will be burned in a milisecond if it meet even low DC curent (or voltage across primary). All the transformers are checked before the dispatch and tested for the desired inductance of the primary.
Cheers!

 

[Delta Sigma]

Once more important note! Be sure that coupling caps in front of T14/1 are not leaky and be sure that you dont put any DC on primary side (blue blue leads). It means even measuring the resistance of the primary (it's around 3kohms) because primary side is winded with the ultra thin wire what will be burned in a milisecond if it meet even low DC curent (or voltage across primary). All the transformers are checked before the dispatch and tested for the desired inductance of the primary.
Cheers!

Any cap types to avoid? I believe I read that wet tants fail to a short so I assume those would be a bad idea.

I have a couple Russian metalized paper caps lined up for this build. Any recommendation on how to test for DC leak? I have an LCR but it’s just a cheap one (DER EE DE-5000).

 

[Moby]

Any cap types to avoid? I believe I read that wet tants fail to a short so I assume those would be a bad idea.

I have a couple Russian metalized paper caps lined up for this build. Any recommendation on how to test for DC leak? I have an LCR but it’s just a cheap one (DER EE DE-5000).

Akg used tantalum caps. They sound pretty nice but as you stated they fail to a short and than DC kills the T14/1. Also, paper in oil caps generally have a tendency to leak so that should be another type to avoid. Unfortunatelly both of the types sounds "interesting".

 

[garp]

I received mine ! Super nice tranny !

 

[Vac11]

All Ü11 (C12a) preorders were moved here:
https://groupdiy.com/threads/feeler...-transformers-c12a-414eb-414ep-p48-etc.78668/
Pleas check the new preorder thread!!!

 

[Tubetec]

An LCR meter wouldnt be much good for testing caps for leakage , Its an AC signal it puts out .
Typically in tube amps a leaky cap will show a small dc voltage at the following grid , when you lift the cap from the grid/ resistor the leak voltage rises appreciably . A source of dc voltage appropriate to the cap your testing and a multimeter should be all you need , I have an old Heathkit RC bridge with cap leakage test , comes in usefull at times .

 

[Moby]

All Ü11 (C12a) preorders were moved here:
https://groupdiy.com/threads/feeler...-transformers-c12a-414eb-414ep-p48-etc.78668/
Pleas check the new preorder thread!!!

I will do my best to ASAP show you the progress of the Ü11, Ü35 & Ü54 transformers. Stay tuned

 

[Delta Sigma]

An LCR meter wouldnt be much good for testing caps for leakage , Its an AC signal it puts out .
Typically in tube amps a leaky cap will show a small dc voltage at the following grid , when you lift the cap from the grid/ resistor the leak voltage rises appreciably . A source of dc voltage appropriate to the cap your testing and a multimeter should be all you need , I have an old Heathkit RC bridge with cap leakage test , comes in usefull at times .

Nice! I ended up just using B+ and a resistor. Some of my MP caps were very leaky; decided just to use modern film caps.

 

[wave]

I got my first unit installed into my 251 prototype...
It's amazing! Sounds exactly like my golden sample vintage unit.
We are super happy!

Thanks Srdjan and Milan!
-Dave

 

[LevinGuitar]

Once more important note! Be sure that coupling caps in front of T14/1 are not leaky and be sure that you dont put any DC on primary side (blue blue leads). It means even measuring the resistance of the primary (it's around 3kohms) because primary side is winded with the ultra thin wire what will be burned in a milisecond if it meet even low DC curent (or voltage across primary). All the transformers are checked before the dispatch and tested for the desired inductance of the primary.
Cheers!

After this warning I wanted to know if there is some cap of the current production that "sound" close to one of my favorites, Rifa MP, to use with his T14 transformer. The Rifa now masure 1.33uf, the rest are very very close to 1uf.

The test mic is a MXL V77 without imput cap, Peluso CEK47, GE 6072 and Jensen DBE.

 

[TLRT]

They are working well! Thanks for Moby and Milan!

 

[Murdock]

After this warning I wanted to know if there is some cap of the current production that "sound" close to one of my favorites, Rifa MP, to use with his T14 transformer. The Rifa now masure 1.33uf, the rest are very very close to 1uf.

The test mic is a MXL V77 without imput cap, Peluso CEK47, GE 6072 and Jensen DBE.

The difference you heard was probably more the different capacitance than the different cap Type. I would, just to be sure try another but new 1.3uF cap and compare again .

 

[LevinGuitar]

The difference you heard was probably more the different capacitance than the different cap Type. I would, just to be sure try another but new 1.3uF cap and compare again .

I have a 0.5uf (0.7) Koweg MP that sound very close to 1uf (1.33) Rifa, and some others MP of closer capacitance (1.2-1.4) and they sound different between each other. The MKPs are all strictly 1 uf and do sound different too