Hooking up matching transformer (UTC A22) as a filter (korean style?)

[basstoner]

Need some assistance with pin out for the in/out/ground. Do I connect 4 and 7 together? Do I ground or bridge 5, 6 and CT? Obviously I'm lost.

This is intended to be an inline audio filter. Image of transformer in question below -

http://0303dba.netsolhost.com/utc_a22_transformer1.jpg

[basstoner]

heres an example of one of the korean boxes. note the price.

http://www.ebay.com/itm/UTC-Line-Matching-Interstage-Transformers-CD-MP3-Smartphone-Analog-DA-Converter-/261378939238?pt=Vintage_Electronics_R2&hash=item3cdb661966

[R.G.]

What kind of filtering are you trying to accomplish?

There is a long list of caveats and small print associated with using transformers - well, and inductors, too - as filters. One biggie is noted on the transformer itself - source impedance and load impedances of 500 ohms. The internal quirks and side effects of a transformer-as-filter vary, sometimes a lot, depending on what you drive it with and what you load it with.

To answer the question of how to hook it up, that transformer has four internal windings. Two of them are permanently connected in series. This is terminals 1, 2 and 3, of which 2 is the junction of these two windings.

4-6 and 5-7 are left separated. You can make a CT winding by connecting 5 and 6. You may also parallel the two windings by connecting 4 to 5 and 6 to 7.

Your ohmmeter will tell you this much.

Your ohmmeter will not tell you what the impedances connected to this thing do. The primary (1-2-3) is intended to be used with a 500 ohm source from 1-3. The secondaries can be hooked up three ways. They can be used for 500 ohms (or 500CT) by connecting the CT as shown on the transformer. They can be used as a 125 ohm output by paralleling the two secondary windings as shown. Or they can be used as two isolated 250 ohm secondaries.

But none of this tells you what it will do as a filter.

[basstoner]

so, if i plug my input into 1 and the output into 3, with the grounds into CT, i'll get the effect i'm looking for?

I'm just interested in what it'll sound like, whatever it does to the audio.

[R.G.]

so, if i plug my input into 1 and the output into 3, with the grounds into CT, i'll get the effect i'm looking for?

I'm just interested in what it'll sound like, whatever it does to the audio.

Well, you'll get something through it. It's not clear what effect you're looking for, other than does it do something to the audio.

If that's it, sure, plug your input into terminal 1, take output from terminal 3, and ground the CT on the primary. There are some issues with that.

What this connection does is invert the audio in the midband. The output at 3 is simply inverted compared to the output at 1. The output will probably be very deficient in bass unless you drive the input with a source with an impedance of about 250 ohms. You could expect it to give 40Hz to 20kHz (assuming they didn't lie on the case, and UTC was pretty good about not doing that back in the day) with only minor wobbles and phase shift in the audio.

Every doubling of source impedance cuts an octave (roughly) of bottom off. So a 500 ohm source will only give bass on the output to about 80hz, a 1K source will have a bass half-power point of 160Hz, etc.. You may get peakiness in the treble depending on the nature of your load on 2-3. If it's a lot higher than the specified 250, the secondary is not as damped as specified. A lot of transformers have a peak in the 20-25kHz region, or about. It depends on the load. It might be interesting to hang a 1K resistor across the output just for the damping.

So - unless the trannie is damaged, you'll get audio through. WHAT audio you get through depends as much on what you drive it with and load it with as the transformer itself. If the question is what do you get when you drive it with this and listen through that, you'll get an answer very quickly. But the answer changes with what you drive and load it with.

If similar stuff is used in hyper-priced hifi tweako stuff as shown, don't expect the voices of angels to come spilling out like the advertising for the hif stuff says.

Let us know what you find.