Connecting 3 step up transformers?

I have a box full of these old ADC 1:10 transformers with two primary pins, and 3 pin center tapped secondaries. Is it possible or even desirable to connect 3 of them together for a 1:30 step up for a ribbon microphone?

I'm sure someone more knowledgeable will be along shortly, but I would expect it might do strange things to your frequency response. Plus, wouldn't the step-ups be multiplicative (giving an overall ratio of 1:1000 with three connected in series)?

I guess... I'm not a mic guy..

three 1:10 transformers with primaries wired in parallel, and secondaries in series will give you 30x voltage step up.

The impedance transform is voltage ratio squared.

JR

If the coils don't share the same core, the laws are different. That thing is so small I doubt you could chain them anyway. And 1:10 is a pretty good step up. You would need to learn a lot more though. Measure DCR and figure out what the inductance of the primary and secondaries are (lots of ways to do that depending on what tools you have on hand). Then you need to make a simple test circuit and get a spectrum to see if the low frequency response is good enough to be worth the trouble.

AardvarkBry said:

I have a box full of these old ADC 1:10 transformers with two primary pins, and 3 pin center tapped secondaries. Is it possible or even desirable to connect 3 of them together for a 1:30 step up for a ribbon microphone?

Click to expand...

A ribbon mic has a very low impedance, less that 1 ohm.
If you connect three primaries in parallels, assuming a DCR of each to be about 20 ohms, that will result in 6 ohms added to the source resistance or about 8.5 dB added noise.
Putting 3 secondaries in series is not without consequences either to the HF response.

Thanks for all the info! It sounds like a problematic proposition. Ribbons are noisy enough without adding more noise. I have built a couple with the 1:35 Cinemag, and even those are very low gain. So I definitely don’t think the 1:10 would be enough. I built a mic activator that made a huge difference. A little hiss aside, it’s my favorite mic.

i would guess the magnetic  coupling would not be efficient through 3 separate cores

how do those adc units work with a 57 as a mic step-up?

a little off topic there is an active ribbon thread I've lost track of;
I don't recall if there was mention of grounded base topology but that may be useful for low source impedance of ribbon without xfmr-- if it could be done without damaging ribbon.

Dave P used a pair of transformers in an Altec 458A clone,  Paralleled primaries, series secondaries.  I think there’s something like that in the Jensen app notes. 

I should try that with my sm57. I made a wolfbox with one of them, and it sounds amazing, I love it. It’s my understanding these transformers were used for old military airplane com systems. They’re very well made.

you can rip out the transformer on the sm57 and get better sound, it is an old trick, there was a thread about that a long while back, Soundguy was one of the main instigators,

that ADC has a nice nickel core, you could rip it apart and put a different coil on there for a ribbon, peerless k-241-d is the premium moving coil xfmr, because it has all these taps that you can do strange things with to get the input Z way down, your ADC has no taps so you can not perform that peerless trick.

if you connect 3 transformers together, then your core loss is x3, so your delicate ribbon signal gets lost in all that alloy.

Thanks for all the knowledge CJ. At the risk of straying way off topic, but since you mentioned multiple taps, I have this crazy UTC with 13 taps. I’m sure I could do some cool stuff with it, but I don’t understand it. Can you help me understand some of the possibilities?

That looks like a speech-bandwidth transfomer... frequency response is listed as 200-5k on the can.

Primary looks to be 600 ohm, secondary either 600 ohm or 200 ohm, depending how it's configured. Maybe someone else can fill in any blanks

Line to  Line  600:600/200

freq specs are just minimum requirements probably set forth by the military, it will probably do 20 to 20 kc,  40 to 20 kc at the worst,

CJ said:

you can rip out the transformer on the sm57 and get better sound, it is an old trick, there was a thread about that a long while back, Soundguy was one of the main instigators,

Click to expand...

Wow, that's probably over 15 years ago now!  I remember telling Soundguy about it, either when I was at his place, or on the phone...  ?
Anyway, I personally first heard about the trick from George Massenburg. 
Impedance is real low, as is level.  But for certain signals, into a pre that likes the impedance and has sufficient clean gain, I think it beats even the super-duper replacement transformer jobs that folks started offering since.

i remember it working well on a kick drum, low freq response was omproved, probably because the small nickel core was not getting saturated with a bass pulse, and yes, level was low on vocals, so probably not good for that. probably would work close to a 4 x4 cab with some crazy guy playing Canibal Corpse(sp) in D flat or something,

wow Mr Boogie, you were right, good memory, 15 years ago almost to the day!>

https://groupdiy.com/index.php?topic=14541.0

wow, everybody was full of piss and vinegar back then! especially the east coast people,  what did George Carlin say about east and west/

"LA is a small woman saying F me, New York is a big dude saying F you!" 

Haha, I just read a few pages of that thread, thanks C.J.  Piss and Vinegar is right! 

You still taking trips to 'the hole' dude?

Good ol' George Carlin had it about right I reckon