Hello - read through every thread I could find on stereo to mono conversion, heated debate on what the right technique is and I'm certainly not broaching that topic here.
I have a couple 111C western electric repeating coils I was hoping to use for this application as they are just collecting dust otherwise. Would someone be able to assist with the wiring diagram for these? I'm fairly green when it comes to reading a schematic and building my own solution thereafter though I'm sure this isn't a massively complex task once you know where the wiring goes.
I've included the 111C diagram below for reference, really appreciate any advise you're able to give.
Thanks again!
I have a couple 111C western electric repeating coils I was hoping to use for this application as they are just collecting dust otherwise. Would someone be able to assist with the wiring diagram for these? I'm fairly green when it comes to reading a schematic and building my own solution thereafter though I'm sure this isn't a massively complex task once you know where the wiring goes.
I've included the 111C diagram below for reference, really appreciate any advise you're able to give.
Thanks again!
So you are using old school AT&T ( probably Bell ) telephone transmission line ( long distance ) for speech ?
Did you notice the impedance --- not normal tube values ?---600 ohms/600 ohms /150 ohms/600 ohms .
So you are going to use them for ---?
Going through one of my tube books I cant find any output tubes that will work at those low values correctly.
They are used also to operate exchange relays in Strowger type analog exchanges , as an ex BT guy I have never known anybody to try and use them for hi-fi audio but I don't know everything and maybe somebody here builds amplifiers using them ??
Did you notice the impedance --- not normal tube values ?---600 ohms/600 ohms /150 ohms/600 ohms .
So you are going to use them for ---?
Going through one of my tube books I cant find any output tubes that will work at those low values correctly.
They are used also to operate exchange relays in Strowger type analog exchanges , as an ex BT guy I have never known anybody to try and use them for hi-fi audio but I don't know everything and maybe somebody here builds amplifiers using them ??
Hey Duncan - they aren't for use within the amplifier. To my knowledge they have one main purpose (believe they are very popular in Japan and recording studios in this use), but generally wired to the output of a digital source and the audio is just passed through them for 'color' or more of an analogue sound. They were originally used to extend signals in telephone wires over long distances I believe while also seeking to match impendence to or from the source (something like that if I remember correctly).
Here's a picture of such an application. https://auctions.c.yimg.jp/images.auctions.yahoo.co.jp/image/dr000/auc0501/users/1b1a626132a9534f22bb110e3ffdeaf3a6e60d33/i-img640x480-1548676679pwsnnz122213.jpg
Since they are 1:1 for line level transmission I was hoping to wire them in a way that they'd take a stereo analogue out from DAC and convert to mono signal for preamp input. Here's a diagram I've found where someone did this with triad transformers (TY-146P) and here's the diagram that was used.
It looks pretty straight forward but just not clear enough for my lack of knowledge to understand where to put the wires for my application. Thanks again!
Here's a picture of such an application. https://auctions.c.yimg.jp/images.auctions.yahoo.co.jp/image/dr000/auc0501/users/1b1a626132a9534f22bb110e3ffdeaf3a6e60d33/i-img640x480-1548676679pwsnnz122213.jpg
Since they are 1:1 for line level transmission I was hoping to wire them in a way that they'd take a stereo analogue out from DAC and convert to mono signal for preamp input. Here's a diagram I've found where someone did this with triad transformers (TY-146P) and here's the diagram that was used.
It looks pretty straight forward but just not clear enough for my lack of knowledge to understand where to put the wires for my application. Thanks again!
The 111C is an *excellent* audio transformer. They were used by the *hundreds* in cascade on transcontinental broadcast lines, where any faults would add-up, and AT&T made half their profit on broadcast links, so they were incredibly good. (The UK Post system also had super-good transformers, but the US's vast distances and commercial interests were fertilizers.)
For making mono _I_ would just use two resistors, unless there were some COMPELLING reason not to. The crappiest resistor is better than the best transformer. But obviously this is a religious issue.
For making mono _I_ would just use two resistors, unless there were some COMPELLING reason not to. The crappiest resistor is better than the best transformer. But obviously this is a religious issue.
Hey PRR,
I don’t disagree on the resistor path! Though I do have several compelling reasons to do this
1. why not? I have them and they are just sitting here for the moment
2. As you said they are excellent audio transformers and years back I ran the output of my dac into them with great effect. Stripped all the wiring for a different project some time ago however.
3. Seems reasonable that they wouldn’t have a negative effect on the audio path, if anything they may add to it.
4. Figure it’s worth a go
Just need some help on the wiring or would love to better understand the diagram so that I’m able to work it out myself thereafter.
I don’t disagree on the resistor path! Though I do have several compelling reasons to do this
1. why not? I have them and they are just sitting here for the moment
2. As you said they are excellent audio transformers and years back I ran the output of my dac into them with great effect. Stripped all the wiring for a different project some time ago however.
3. Seems reasonable that they wouldn’t have a negative effect on the audio path, if anything they may add to it.
4. Figure it’s worth a go
Just need some help on the wiring or would love to better understand the diagram so that I’m able to work it out myself thereafter.
I do not have to tell you how much you could sell them for.
That "diagram I've found" may be part of your puzzlement. It's got 4 wires out of a 3-connection plug. Draw it out correctly then drop the W.E. artwork in.
The output is floating and nominal 1,200 ohms; it probably needs one side grounded for sanitation but probably does not need a terminating impedance.
That "diagram I've found" may be part of your puzzlement. It's got 4 wires out of a 3-connection plug. Draw it out correctly then drop the W.E. artwork in.
The output is floating and nominal 1,200 ohms; it probably needs one side grounded for sanitation but probably does not need a terminating impedance.
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Agreed though I acquired them for free so I’ll hang on until the need strikes to sell them.
Thank you so much for organizing that properly! Gives me much more clarity. I’ve attached a sketch where I’ve drawn the transformers as the numbers are stamped on physically on the top. Believe I’ve got this correct from your drawing above. Only change is that I’m using regular analog jacks instead of headphone jack in.
Thank you so much for organizing that properly! Gives me much more clarity. I’ve attached a sketch where I’ve drawn the transformers as the numbers are stamped on physically on the top. Believe I’ve got this correct from your drawing above. Only change is that I’m using regular analog jacks instead of headphone jack in.
Attachments
I had several pairs and found them quite useful for isolation in measurement hardware and other places where 600 ohms was suitable. I initially used a pair to test the feasibility of converting my amps to balanced input transformers years ago, must have worked since the current ones all have input transformers.
Last nearby lightning strike here was considerably mitigated by surge currents not getting through the transformers at the other end of a 12 foot run of balanced cable and into the amplifiers... Some balanced transformerless solid state gear was damaged however - took 2 weeks to fix the damage to crossovers and processors.
Last nearby lightning strike here was considerably mitigated by surge currents not getting through the transformers at the other end of a 12 foot run of balanced cable and into the amplifiers... Some balanced transformerless solid state gear was damaged however - took 2 weeks to fix the damage to crossovers and processors.