Tiny Neutrik NTE10/3 transformer for microphone output 10:1 for tube and FET

[Rossi]

I wouldn't be surprised if NTL and NTM had inside NTE transformers.

Based on what?

 

[ln76d]

Based on what?

Based on nothing
Speculation
Can is really small so transformer will be similar sized but in fact specs are little bit different (max input level) so these aren't the same.

 

[Matador]

There were for some time, over the web, some bulls**t stories about ccda circuits as it have really low impedances before the transformer, since it look like cathode follower etc. If someone will calculate impedance with online tube circuits calculators - yes it's really low but in fact it isn't. There is somewhere here my topic where PRR (if i remember corectly) made calculation for the output impedance. Impedance in the most of these circuits is rather high.
I tried in stock circuits low ratio transformers and the lowest which works well was 6.3:1.
I was hoping to mod some ccda to use 12at7 and 3:1 transformer but i couldn't go lower than 6.3:1.
Always sucks

Yes, the stock setup isn't biased very well, and these designs (stock) don't pull much idle current to keep the filtering simple.  The output impedance is roughly 1/gm, but gm drops as a function of current.  And the 270k resistor is probably much too high at these design points.  So the actual output impedance is probably a few k (and I'm just spitballing here).  It pretty easy to re-bias the tube up to around the 1 mA mark and then the output impedance would drop down below 1k.

However not so many people are running into real 600 ohm inputs either.  Into a preamp of at least a few k, even the stock values aren't too bad.

 

[hans a]

Hi, reopened..
Is this cheap transformer suitable for a first DIY mic-preamp?
I want to learn about impedance bridging using a transformer and a Common emitter amp with an output transistor.
Maybe max 32db gain?
Best regards Alex

 

[RuudNL]

It is not screened, so it will pick up a lot of hum in case there is a transformer in the neighbourhood...

 

[orange4boy]

Would these work as mc cartridge step up transformers or are they too small?

 

[Marik]

Would these work as mc cartridge step up transformers or are they too small?

It should "somehow work", but won't be an optimal choice, unless you have a high impedance cartridge (some 30 Ohm and up). The low impedance ones would need quite a bit higher ratio of some 1:30. From memory the NTE10/3 Pri inductance is somewhere 80--90H. This makes it more like a 20KOhm:200 Ohm transformer, which will need to be connected backwards. The 200 Ohm side is way overkill with high copper resistance and as a result added high noise level and not enough step up.

Best, M