AGAIN : What to Build:Peerless/Altec trafos (NOW WITH PICS)

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Silvas

Well-known member
Joined
Aug 15, 2006
Messages
727
Location
Chia, Colombia
finally i had some time to upload some pics of my unknown trafos who are begging to be used on something...

Hope someone can help me identify them.

Thanks!

http://a161.ac-images.myspacecdn.com/images01/44/l_f4a715fa16b16fda097588958c9145b8.jpg
http://a537.ac-images.myspacecdn.com/images01/47/l_442d74751d8227f13a0e77094f22eaa8.jpg
http://a302.ac-images.myspacecdn.com/images01/42/l_43bced837c451d3cf4f6ba1185613f65.jpg
http://a891.ac-images.myspacecdn.com/images01/32/l_28199db768741b682816a3ec7b8a7f22.jpg
http://a906.ac-images.myspacecdn.com/images01/44/l_040bc723684ca99f600497f99100dd71.jpg
http://a464.ac-images.myspacecdn.com/images01/17/l_b3227b409a4753ae69eae9161844ef67.jpg
http://a104.ac-images.myspacecdn.com/images01/46/l_4cc6c550bdd7084cbafbff1bf5b3c39f.jpg
http://a32.ac-images.myspacecdn.com/images01/19/l_41b7a09698266bfa5053e965d94a2c9f.jpg
 
16263 and 4627 are the Peerless #s. I don't see those #s on any other pieces, but they fall very close in # to the 428 and 429 amps from the mid 1950's. Likely custom part #s for Ampex. Have you tried the Ampex user forum/list?

4627 is an input.

16263 is an output.
 
I'm sure you'll have to make some friends there and talk about them some to get anywhere.

Otherwise check out the various info here for determining ratios and impedances. I hope you took note of the tubes feeding / being fed by these units. That would be your biggest source of easy info.
 
Those peerless are most probably very hi-end stuff.

Where does it comes from? If you have a chance, check the ciruit where it came from, at least what was it driving (a tube grid, transistors, an opamp?), or in case of an output, what it was driving... (line, speakers?)

Then check the DC resistances of the windings, the inductance, and finally put a scope and a signal generator on it. Use a pot in series with the input, and another pot shunting the output, both wired as reostats, and start dialing the impedances, and checking frequency response vs loss to see how it works better.

So, now you have turns ratio, and an idea of what impedances it needs to work best, and what levels it takes to saturate, and that´s really all you need to know to use it. I do it all the time. After you get your transformer jig all going, it becomes easy. You will be amazed at how almost any transformer can be used for audio with good results, even power transformers, or low end narrow frequency transformers. If you know what you are doing, you can get cheap and aparently unuasable transformers to perform well and even sound great or at least sound special, like nothing else, you know... It all depends on how you use it, and where you use it. That´s all you need to do. Besides, that´s lots of fun after you get started.
 
no clue about how they were connected or to what they were connected...as i said before, the old ampex machine was almost destroyed, but thanks for the replies !
 
Does these kind of transformers have something like an "standard" pinout to use as a guideline for measuring? i´ve seen many photos and other models look very alike...it will be a starting point.
 
Pull up a wiring diagram for some UTC LS, HA, or A units. 80-90% of all audio transformers will follow similar winding logic. It's a jigsaw puzzle; start with an ohm meter on one lug and try every other lug until you get a reading. Try every lug. Write all the relationships down. Move to the next lug. Do them all. There's your schematic for the transformer. Whichever set of windings ( maybe one, maybe two windings joined in series) add up to roughly 40-90 ohms is the 600 ohm winding, assuming one is present. That's almost always an assumed value for one side given the orginal usage. Put test tone to either primary or secondary and measure level, then measure the other windings output difference from the input to the other winding. Apply the various formulas for turns/impedance ratio. Get an inductance meter and check that reading for an idea of hi-fi potential; these are peerless form an Ampex machine so it's a safe bet in the first place that they are high quality. There's a ton of variations here; subtle differences in approach depending on test gear and iron at hand. Your answer may not be exact but will be close enough to get a working idea.

I have to do this with every transformer I find and they'd all be useless without doing it, since the data is NEVER available. The people who used this stuff when it was new are all dead, or fast approaching it.
 
Send it to CJ! I'm sure he can do some butcher work and some nice iron "porn" pics :wink:
butcher.jpg
 
[quote author="Moby"]Send it to CJ! I'm sure he can do some butcher work and some nice iron "porn" pics :wink:
[/quote]

Sure then we'll understand them perfectly and they will be dead! :wink:
 
today i made some measurments to the trafos, one of them looks good, the other has a broken winding i think...tomorrow i´ll post a drawing with my findings to see if someone help me finding a use for them...both of them has 4 windings, 2 of them low impedances with a center tap i think?
 
I just made this basic measurments....

I measured all the resistances of the windings, both transformers have the same pinout numbers but with different footprints. for the voltages, i used a 1.23v 1kHz tone, which dropped to 1.1v when connected to the windings. All resistances are in ohms.

In the 1154, between pins 8 and 10 there is no resistance, probably a broken winding...but i do get some voltage if i measure here...something like 3.6v.


http://a772.ac-images.myspacecdn.com/images01/15/l_3787e75ad04a859d5e8793bd8dded2d3.jpg


Thanks!
 
On the 1154 connect 8-9 and measure 7 to 10. Sometimes a winding will have a value right near the turn-over part of my meter and not show up. If you are seeing voltage then there's something still connected.

I'm inclined to think the 1154 is an output with 1-6 being the 600 ohm secondary. Though it may be an input. 8-10 may be either a bad half of the primary (if output) or a feedback winding. Lower voltage reading suggests lower DCR value and impedance as opposed to open winding. I can't imagine a step-up voltage value as a stray reading, and you wouldn't get anything if it's truly open.

1153 looks like a 1-6 600 ohm primary input to tube grid(s) transfomer.

If you do the voltage measurements again with a 510 ohm resistor inline to the 1 and 6 taps (3-4 connected) you will more approximate a correct input impedance to the transformers, and get more exacting readings from the other windings. At least worth doing for comparison, even if not exactly correct. you may or may not see a big change in transferred voltage ratio.

Put the 7-10 sides into a hi-Z input (direct box useful) and play some music through 1-6; have a listen. If nothing / nothing useful coming out of the 1154 then switch to 7-9.
 
for mic to grid, I would try 115 with primaries in paralell. Like + to 1+3 and - to 4+6. On the secondary, use the inner winding for grid, and the outer winding for ground, connecting 9 and 8 together, 7 to grid and 10 to ground. You can ground all other pins that are not part of any windings, because they might be shields. If you are lucky, these sounds as good as a K241D. From the resistance readings looks like it would be lower ratio, like 150:600:30k or so... Also, looks like the same vintage.
 
nothing useful on pins 7-10, but useful on 7-9 of the 1154

useful on pins 7-10 of the 1153

so

these transformers can be used as input/output on a tube mic pre ? a solidstate pre? a comp? what do you think?
 
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