swapping mic input transfos

[Guest]

Howdy!

Testing a problem, I ended up swapping an altran c3402-2 mic input transformer for a cinemag cmmi 8 pca.

Wouldn't you know it, I think it sounds better! In any case, the only difference I can find in specs is 100K secondary load impedance (cinemag) vs. the altran's 10K secondary load impedance.

I guess I"m just wondering if there are any obvious electrical problems (down the road) doing this...

Thanks!

kelly

 

[peter purpose]

CMMI 8PCA is 10K secondary... so no problem.

 

[Guest]

Thanks for getting back...

Just curious...I'm trying to learn. What am I reading wrong here:

(from the spec sheet):

"1 kHz, -20 dBu 150S input, 100K secondary load impedance"

Again, thanks...I'm gonna leave and swap the other too. They sound WAY better to me.

kelly

 

[tk@halmi]

Kelly,

You should not load the Altran transformer with 10k. This is a step-up transformer and you are loading the crap out of it with a 10k termination. Of course the Cinemag sounds better because you actully get a decent bandwidth with the 100k load. Use 100k on the Altran as well. If the spec calls for 10k termination it is WRONG!

Cheers,
Tamas

 

[peter purpose]

Ah, you're talking termination.
The Cinemag needs to see 100K followed by 9K76 & 22pF.
Sorry about the confusion.

peter

 

[pmroz]

.
... if you're swapping in an Ay Pee Eye type pre like Fabio's boards, Reichenbach at Cinemag said just the 100k R, without the extra 9K76 & 22pF cap, should work fine... and mine do.

Are input trafos generally terminated at 10 times secondary impedance? So for a 10k secondary, load with 100k? Maybe that's the confusion, between trafo spec and termination... or maybe the confusion is in my head...
Paul

 

[rafafredd]

Yes, usualy 10 times the rated impedance.

 

[Guest]

I'll follow this thread...good reading.

The swap is for a hamptone jfet mic pre. As soon as I understand better what the transformer needs to see on its secondary, I'll probably have a better idea.

Thanks to all who've responded!

kelly