Output transformer question

Hi all,

I have two good quality 1:1 output transformers same size, same configuration. I think one is a copy of the other. The only difference that I can measure is in the inductance, which is higher in one than the other. How is that likely to affect the sound? Could they be used as a stereo pair?

Thanks

All other things being equal--which they rarely are--the xfmr with higher primary inductance will have better bass response.

how much higher is the inductance?

if one of them has much more primary inductance then leakage inductance and stray capacitance may also be much higher, which will have influence in top end response too...

lo inductance -> less bass (depending on driving impedance), good topend response

hi inductance -> good bass response, limited HF response, ringing etc...

steff

For a 1:1 trannie, what would 'very' high and 'very' low inductance be? Just a ballpark figure..

For a 1:1 transformer, I would consider 10H primary inductance "high" and 250mH "low".

Thanx Jakob :thumb: My Monacor LCR meter went south some time ago and I really need a new one. Cheap! Any suggestions?

[quote author="Steffen"]lo inductance -> less bass (depending on driving impedance), good topend response

hi inductance -> good bass response, limited HF response, ringing etc...

steff[/quote]

This is often true, but not always.

Shunt capacitance usually increases with more turns, so a transformer winding with greater inductance usually has more distributed shunt capacitance. But this is not a direct consequence of inductance itself, but rather a parasitic effect that can be minimized through construction techniques. Paradoxically, the transformer with more windings might have better HF response to some degree (especially if it's a stepdown type) due to increased primary-to-secondary leakage capacitance.

Where's Whitlock? He can explain this stuff much better.

[quote author="sismofyt"]Thanx Jakob :thumb: My Monacor LCR meter went south some time ago and I really need a new one. Cheap! Any suggestions?[/quote]

got this one, 56 euro, measures inductance up to 20H, plus capacitance, frequency, etc...

steff

56euro? Whoha! Where? Frequency? What's the range?

Many :?: , eh? :green:

How about a META tool thread? (Or is there one allready )

The cheapest ones I've seen are about 150euro :evil:

[quote author="sismofyt"]56euro? Whoha! Where? Frequency? What's the range?

Many :?: , eh? :green:[/quote]


www.elv.de

freq.counter is 200kHz only I think..... but hey, you even get temperature probe with the unit ....sometimes handy for checking heatsinks (no more burning the fingers :green: )

steff

Super Steffen. I'm gonna order one asap!

:thumb:

ops...looked at the specs.... freq.counter is 20MHz not 200kHz...cool

steff

That's pretty frickin' cool for a 56euro meter! :grin:

I just got home and measured the transformers again. First of all, they're 1+1:1+1 - two primaries and two secondaries. I'm not sure my methodology is right, though. I measured the inductance of each coil, not from one coil to the other. Is that right? I'm not sure how to measure leakage inductance. Here's what I got:

coils in parallel-

T1 inductance 1.256H, resistance 21.7 ohms

T2 inductance .374H, resistance 22 ohms

coils in series-

T1 inductance 15.8H, 41.7 ohms

T2 inductance 5.3H, 45.3 ohms

So this is telling me that T1 is likely to have more lows and less highs than T2?

Actually, a 1:1 transformer probably has one of the flatest curves of any ratio. Not much self res, and good down to dc.
cj

Hi there,

can one of you tell me how I can tell wich is the primary and wich the secondary winding on an audio-transformer?
AND: I have some non-pcb-versions: Are the colors of the connector cables standardized somehow?

Thanks

Chris

[quote author="chriss"]can one of you tell me how I can tell wich is the primary and wich the secondary winding on an audio-transformer?
AND: I have some non-pcb-versions: Are the colors of the connector cables standardized somehow?[/quote]

- There's no way (that I know of) to figure out what way a transformer was ment to operate. And then, on the other hand, it dosen't really matter. There's no intrinsic "right" way to shove signal through a transformer - one way is as good as the other. Depending, off course, on the ratio and inductances you need.

- Wire colours are often standardised within one manufacturer's transformers, but there is no such thing as an universal standard.

Jakob E.