What's the difference between these UTC O-12?

[Ilya]

Here're the couple of o-12s which seem to be the same although their look differs:

Is anybody aware what's the difference is (except the look) if any?

 

[edanderson]

the second one is older. the whole ouncer line used to have those engraved designs with only the model number. later they went to ink with all the info. they work the same.

ed

 

[Ilya]

Thanks Ed!
That makes sence now.

 

[thestudio]

I purchased 0-12 transformers that have TRW stamp but all specs are the same ? how different compared to UTC?

 

[edanderson]

trw bought utc. same thing.

ed

 

[rascalseven]

FWIW the 'ouncer' line of UTC transformers were also available in an octal socket plug-in format. These were given a "P" prefix instead of "O." Therefore, the P-12 is the same transformer as the O-12, just in a plug-in package.

I guess these are less known, or maybe they were less used, than the standard ouncer package, but for whatever reason you can often find the "P" version for less money than their "O" counterpart. :wink:

I got my three P-12's for $14 each!

:grin:

JC

 

[thesystem]

Didn't want to start a new thread on the same subject so here goes.

I managed to get my hands on 3 UTC 0-12 ouncers. The last photo in my gallery below is the older one if I understand correctly from edanderson. What I'd like to know is how to check if these transformers are in a good working condition. I haven't finished my two 1176 comps yet so can't just put them in and try.
The pins on the older one seem to be in a worse state than the other two. I've added some photo's in the member gallery, is there a way to make up if the pins will be ok?

gallery: http://www.groupdiy.com/index.php?action=gallery;su=user;cat=9;u=47503

 

[emrr]

measure them

 

[thesystem]

measure them

Yeah I know that, but wat do you measure? What numbers are expected?

 

[edanderson]

get the original 1176 schematic from the JBL pro audio site (google) and hook up the O-12 as it is used in the 1176.  you can feed audio through the transformer and see if it has decent frequency response etc.  the hookup configuration in the 1176 should drop the level a few dB, but otherwise you should get relatively clean audio through the transformer.

you'll need a setup like this when you do the 1176 calibration anyway, so you may as well figure it out now.

you could test the DC resistance of the transformer with a multimeter, but for some reason many people have trouble with this, and it won't definitively tell you if the transformer is working or not anway.

ed

 

[fazer]

My understanding of ouncers is they have +8 dbm headroom.  Are they adequate for a line level device? 

You would need to pad the input and then make up the output with a different transformer.  Is that how a 1176 is built?

 

[thesystem]

get the original 1176 schematic from the JBL pro audio site (google) and hook up the O-12 as it is used in the 1176.  you can feed audio through the transformer and see if it has decent frequency response etc.  the hookup configuration in the 1176 should drop the level a few dB, but otherwise you should get relatively clean audio through the transformer.

you'll need a setup like this when you do the 1176 calibration anyway, so you may as well figure it out now.

you could test the DC resistance of the transformer with a multimeter, but for some reason many people have trouble with this, and it won't definitively tell you if the transformer is working or not anway.

ed

Ok so I'll better wait till I've finished hooking up my 1176 and then test the 0-12s. Is sending white noise through the transformer a nice way to see the response of the 012? What would actually happen if the 012 isn't working properly anymore? No sound? bad freq. response? noise?
Thanks

 

[edanderson]

My understanding of ouncers is they have +8 dbm headroom.  Are they adequate for a line level device? 

You would need to pad the input and then make up the output with a different transformer.  Is that how a 1176 is built?

yes, look at the 1176 schematic.  the input attenuator is before the transformer.  the gain reduction FET after the transformer will distort if the signal level is too high, so typically the level is reduced substantially by the setting of the input attenuator and a little by the step-down ratio of the transformer.  the preamp and line amp stages after the GR FET bring the level back up.

ed

 

[edanderson]

Ok so I'll better wait till I've finished hooking up my 1176 and then test the 0-12s. Is sending white noise through the transformer a nice way to see the response of the 012? What would actually happen if the 012 isn't working properly anymore? No sound? bad freq. response? noise?
Thanks

why wait until you have the entire 1176 built?  just run some music through the O-12 at a reasonable level and listen to it.  most of the possible problems would result in no sound or severely degraded/distorted sound -- you would hear the problem right away.  noise is unlikely unless you are picking up interference from another source.

there are also programs like RMAA rightmark audio analyzer that can do frequency response tests using your soundcard.  use google or search this forum to find out more.

ed

 

[lassoharp]

What I'd like to know is how to check if these transformers are in a good working condition.

.


Hook up some test leads and pass real audio through them.

I got my three P-12's for $14 each!

That's a sensible price.

Anyone ever try using the 15K:600 version ouncer and run it as bridging input?  1176 shouldn't be hurting to overcome the gain loss.  Probably cheaper than market price for the 12s

 

[Greebok]

the second one is older.  the whole ouncer line used to have those engraved designs with only the model number.  later they went to ink with all the info.  they work the same.

ed

I've just built the 1176 with older version of the UTC o-12 (with engraved logo) and the compressor sounds darker and has pretty quiet input (around -12dB lower) in comparison with the 1176 with Ed Anderson's version of the input transformer.
So does the original o-12 sound actually dark and quiet?  Or have I got bad transformer?  ??? (Though I don't hear any distortion)
Has anybody any idea? Help please!
Thanks,
Serg.

 

[mjrippe]

The 1949 UTC catalog specs the O-12 at 40-15k, 0dB max level.
The 1962-3 catalog specs 30-20k, +8dBm

So obviously improvements were made between the early and later ones.  (49 has engraved case, 62 has printed).

 

[emrr]

You should not have a level difference.

 

[Greebok]

The 1949 UTC catalog specs the O-12 at 40-15k, 0dB max level.
The 1962-3 catalog specs 30-20k, +8dBm

So obviously improvements were made between the early and later ones.  (49 has engraved case, 62 has printed).

Very useful info! Now I see..
Thanks a lot!  :

 

[emrr]

But what does the 1955 look and spec?  : ). And actually measure?