DIY Transformer mojo box???
Old 5th October 2008
  #1
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Talking DIY Transformer mojo box???

My tech spoke of building a little enclosure with just input and output jacks, whereupon you would have a set of input transformers inside that are simply there to color the audio.

Can you just wire up 2 sets of trs sockets to a pair of input transformers?? So you have the input going to the primary and the outputs coming from the secondary??

I'm guessing a pair of 1:1 input transformers from Cinemag or UTC.

Any suggestions??

I'll ask my tech too.

Peace
Illumination
Old 5th October 2008
  #2
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I did, except I did it with a pair of old Jensen outputs 1:1 600:600. Did work, but have since shuffled them into other uses. I don't think you'd find many input trannies that are 1:1.....but if you have a mic pre without input tranny on purpose you could make a box of inputs to go into it with giving you options....
Old 5th October 2008
  #3
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Talking So ...

Quote:
Originally Posted by Karloff70 View Post
I did, except I did it with a pair of old Jensen outputs 1:1 600:600. Did work, but have since shuffled them into other uses. I don't think you'd find many input trannies that are 1:1.....but if you have a mic pre without input tranny on purpose you could make a box of inputs to go into it with giving you options....
600:600 output trafos are an option too?? Hmm..

I ask this because I noticed in another thread that a pair of Stancor WF30s were put to use in an ART PRO VLA, however, they were simply inserted at the inputs of the PRO VLA itself and did not really become as much a part of the circuit as they were there for flavor.

Now the WF30s are input trafos and are 1:1, but the impedance was variable, from 250:250 to 600:600.

So i could just use output trafos too. Makes things a little more interesting.

Lots of UTC iron on ebay at the moment, my biggest beef is some of them have tons of taps.

Thanks for the help.

Peace
Illumination
Old 6th October 2008
  #4
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Hi
When using any transformers you SHOULD be adding suitable components (usually resitance, capacitance or both) to ensure the response is reasonably 'flat'.
600:600 tend to need less compensation than higher impedance varieties or where you have step up / down ratios.
Of course if the intention is to mess up the response then just wiring them up will do!
Whatever happens you are unlikely to damage any other gear (but not impossible).
Matt S
Old 7th October 2008
  #5
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Quote:
Originally Posted by illacov View Post
My tech spoke of building a little enclosure with just input and output jacks, whereupon you would have a set of input transformers inside that are simply there to color the audio.

Can you just wire up 2 sets of trs sockets to a pair of input transformers?? So you have the input going to the primary and the outputs coming from the secondary??

I'm guessing a pair of 1:1 input transformers from Cinemag or UTC.

Any suggestions??

I'll ask my tech too.

Peace
Illumination
The input to one piece of audio gear is nothing more than the output of another piece of gear. For your purposes you should consider using a 1:1 ratio "output" transformer. Implementing an input transformer can be tricky.

Tip: For more mojo check out tranformers with let's say... less than stellar specifications. A nickel core output transformer from Jensen Transformers (with stellar specs) isn't going to help you much.
Old 7th October 2008
  #6
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Talking Care to...

Quote:
Originally Posted by vince @ speck View Post
The input to one piece of audio gear is nothing more than the output of another piece of gear. For your purposes you should consider using a 1:1 ratio "output" transformer. Implementing an input transformer can be tricky.

Tip: For more mojo check out tranformers with let's say... less than stellar specifications. A nickel core output transformer from Jensen Transformers (with stellar specs) isn't going to help you much.
Recommend some with less than stellar specs??

I already know about how funky the UTCs/Stancor's sound.

Heard some good things about Tamuras.

Any others??
Old 7th October 2008
  #7
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Apparently Edcors are quite good like that, not tried it. Other than that anything steelcore, like Cinemag CMOQ-2S. Beyers are funky.
Old 7th October 2008
  #8
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Hi
Pick a transformer that will start to saturate at say +6dBu or thereabouts for more 'effect'.
Super clean like Jensen and those that will handle +24dBu at low frequencies are unlikely to have sufficient colouring. Othewise you may not be able to 'drive' them hard enough before the previous stage 'clips', which is generally not a sound you want.
Get your 'tech' to put croc clips on a couple of cables so you can simply clip on and 'hear' what any given transformer sounds like. Try any you can lay your hands on. Output transformers from OLD tranny radios? All will do something.
Matt S
Old 7th October 2008
  #9
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Thread Starter
Talking For this particular project...

Quote:
Originally Posted by Matt Syson View Post
Hi
Pick a transformer that will start to saturate at say +6dBu or thereabouts for more 'effect'.
Super clean like Jensen and those that will handle +24dBu at low frequencies are unlikely to have sufficient colouring. Othewise you may not be able to 'drive' them hard enough before the previous stage 'clips', which is generally not a sound you want.
Get your 'tech' to put croc clips on a couple of cables so you can simply clip on and 'hear' what any given transformer sounds like. Try any you can lay your hands on. Output transformers from OLD tranny radios? All will do something.
Matt S
I'm going to be the tech

I'm definately going to look into it.

Thanks

Peace
Illumination
Old 21st October 2008
  #10
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This sounds pretty cool.
Anyone have a good suggestion regarding
off-the-shelf output trafos besides Edcors?
I have several peices that are sort of ho-hum
that could use some vibe.
Old 22nd October 2008
  #11
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Hi,
This is an interesting discussion. I am interested in this as a small DIY project.
Would it be too much to ask if any of you guys does this, to post some images that show how you ended up wiring things? That would be swell.
Also, if you have links to good places for purchasing specific models of the "not so stellar" transformers, that would be great too...
Anyway, we could make this page a resource for anyone (like me) who might be interested in a little project.
Thank you for your posts!
p.
Old 22nd October 2008
  #12
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I have found that most cheap, underspecced transformers sound ugly..
I guess you need 'vintage' models, not cheap ones...
Old 28th October 2008
  #13
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If you care try different core materials. Audio transformer behaviour is highly dependent on the corematerial. Compare steel to nickel/steel to high nickel cores.
Old 29th October 2008
  #14
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i wired an DI i was making with an XLR input so i could use the transformer directly. it uses a JLM 1:4 mic input transformer backwards.
a simple pair of gender changers let me use it to set up or down the gain as well.

cant say its been of any use so far but its good to have something else to play with when it didnt cost me anything except the time to drill an extra hole in the box.
Old 16th November 2010
  #15
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nonamesleft's Avatar
 

Quote:
Originally Posted by illacov View Post
My tech spoke of building a little enclosure with just input and output jacks, whereupon you would have a set of input transformers inside that are simply there to color the audio.

Can you just wire up 2 sets of trs sockets to a pair of input transformers?? So you have the input going to the primary and the outputs coming from the secondary??

I'm guessing a pair of 1:1 input transformers from Cinemag or UTC.

Any suggestions??

I'll ask my tech too.

Peace
Illumination

I had this exact same idea the other day and was hoping there was a way to pull it off. In fact my idea was to daisy-chain like 5 of these together if possible with switches to engage any of them i wished for some juicy transformer saturation. It certainly would be a color box and I love what Carnhills do to a signal especially (or at least I think I do...I'm assuming it has a lot to do with the sound)

Anyway, I have read that looking for a 1:1 will provide the least amount of color (1:10 was suggested as a good number)...also, mumetal is more transparent (metal core is better for color)...and look for transformers that can overload quickly (not jensens). Also, i have been told that input transformers provide the most affect on the sound.

Is all this true? And what transformers should i go for? Do I just wire them up one after another directly pre-preamp?

thanks for the help!
Old 16th November 2010
  #16
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Quote:
Originally Posted by illacov View Post
My tech spoke of building a little enclosure with just input and output jacks, whereupon you would have a set of input transformers inside that are simply there to color the audio...
...I'm guessing a pair of 1:1 input transformers from Cinemag or UTC.
If you'd like colored sound then I'd use an old iron, like Triad A65 A67, UTC ouncers, etc. Generally, silicon steel lamination sound much more colored than Ni core, so if you want to use modern transformers ask for M5, M6.

For some funky colored, fuzzy sound I actually, would not afraid to try... power transformers (!!!). Try to find a smaller core and if you need 1:1 take the one, which has 120V+120V Pri (or of course, Pri 120V and Sec 120V would work too) and then use those windings as Pri--Sec. Most toroidal power transformers should have enough inductance for satisfactory low end performance. For 1:2 (or 2:1) use Pri 120V sec 60V. Last I checked Antique Supply, they had those in small sizes for reasonable price.

Best, M

P.S. Duh! Only now paid attention this is TWO YEARS OLD thread.

Last edited by Marik; 17th November 2010 at 08:18 AM.. Reason: To make P.S.
Old 17th November 2010
  #17
jrp
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what about using two power transformers face to face to come up with a 1:1 ratio?
Old 17th November 2010
  #18
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Quote:
Originally Posted by jrp View Post
what about using two power transformers face to face to come up with a 1:1 ratio?
Well I actually tried this just now with two massive old power transformers rated at 600v each. I have no idea as to what the specs are with these things, though I do know that they draw over 15amps when used for power supply (They were supplying large backup batteries in a gym).

Anyway, when I hooked both of them up (Line level signal->IN->OUT->OUT->IN->Speakers) the signal lost most of its bass content, but the mids and highs were very close to the original signal.

When I hooked them up opposite (Line Level signal->OUT->IN->IN->OUT->Speakers) the sound was close to the original signal but with a slight loss of higher content and the signal was a bit softer and more smooth. It seemed like it cut out a bit of harshness from the mackie mixer it was coming from and took a boost in the highs from the crappy eq way better.......I need to do more testing but i am liking what is happening to the signal for sure! I was using an sm58 and so I need to test out a nice condenser to see what happens.
Old 17th November 2010
  #19
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foldback's Avatar
transformer mojo

It's a two year old thread but people still want transformer tone.

Layered Audio has custom built transformers that can be used to add the sound of iron. Currently she is offering a pair of quadfilar, iron core API replacement transformers for $98 with free priority mail shipping.

Layered Audio

I've used these in my custom work and they sound great.
Old 17th November 2010
  #20
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If there is demand we could make inexpensive transformer specifically designed and optimized to color the sound and "take the edges".

Best, Mark Fouxman
Samar Audio & Microphone Design
Old 17th November 2010
  #21
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Old 17th November 2010
  #22
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Quote:
Originally Posted by Marik View Post
If there is demand we could make inexpensive transformer specifically designed and optimized to color the sound and "take the edges".

Best, Mark Fouxman
Samar Audio & Microphone Design
IMO it's not so much about "taking edges", but about adding punch, weight, sparkle and texture. So far from the transformers I've tried only the vintage UTC do that significantly. The rest is pretty much transparent and simply softens the transients somewhat.

So if anyone came up with a DIY box that I could add into the master insert to add some life to the mix I'd be all for it. Something similar to what a Chandler preamp will do when driven.
Old 17th November 2010
  #23
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Old 18th November 2010
  #24
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Hi
One aspect not mentioned so far is the circuit that is DRIVING the transformer. Simply sticking a transformer on any old output stage will produce different results. Many 'not quite Pro' outputs will be close to current limiting which can produce horrible distortion, and the output reactance of the amplifier (resistance plus capacitance plus inductance) will have a significant effect.
As always you HAVE to look at the broader picture.
Matt S
Old 18th November 2010
  #25
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Quote:
Originally Posted by Matt Syson View Post
Hi
One aspect not mentioned so far is the circuit that is DRIVING the transformer. Simply sticking a transformer on any old output stage will produce different results. Many 'not quite Pro' outputs will be close to current limiting which can produce horrible distortion, and the output reactance of the amplifier (resistance plus capacitance plus inductance) will have a significant effect.
As always you HAVE to look at the broader picture.
Matt S
So true. Another thing is the components used in the old gear especially. Topology, carbon comp resistors, old style caps, etc. Just cause something has a transformer in it doesn't mean the xformer is the sole reason for the "color".
Old 19th November 2010
  #26
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I would think that a well-crafted 'mojo' box could be constructed with an active front end (maybe a Forssell or M99) and either a multitap Xfmr or a handful of transformers that could be switched in and out of the path.

Or maybe something along the line of a Radial Dragster for balanced inputs....
Old 19th November 2010
  #28
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Old 19th November 2010
  #29
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Old 20th November 2010
  #30
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Quote:
Originally Posted by woodfoot View Post
It's not DIY but the new anamod XF Tube may be of interest to you.

Anamod Audio

Definitely on my list of things to try
Looks pretty cool and I do have 1 slot left. How much is it?Do you know?
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