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DIY transformer box to add color
Old 17th November 2017
  #151
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Quote:
Originally Posted by Pollo View Post
I much appreciate you taking the time to clarify. I did some experiments as you suggested, which I had to find the time to do so hence the delay.

In the experiment I used an Echo Audio soundcard with a balanced output and a balanced input. I used a plugin to generate a 40 Hz sine signal of -21.0 dbFS. I then measured the incoming signal with another plugin. To make the data more easy to read I will give the measurements of the incoming signal relative to the output signal.

Going straight from output to input: 0.02 dB.
Going from output to input through 680 Ohm resistor: -0.26 dB.
Going from output to input through transformer: -6.01 dB
Going from output to input through transformer and through 680 Ohm resistor: -6.28 dB.

To be honest I don't really understand what this means. It seems that the signal drop is the same when adding the resistor in both cases. Adding the transformer gives a 6 dB drop which is exactly what I would expect from a 2:1 turns ratio.

The transformers come from a Sony TC-200. I happen to have found a service manual for it online. It includes a schematic.
You stated "2:1" ratio..that would mean you used the 2.5K side as the INPUT..Yes?
Or did You ran the -21.0 input signal into the 600 Ohm side of the transformer?
What IM trying to determine is does the "600" ohm side when used as a input is a true 600 Ohm "LOAD" on the source driving it...
Not 100% sure I follow what you did.
Do you have a VOM?
In the circuit I posted running a 10V RMS signal into the input and measuring across the 680 Ohm resistor you SHOULD read around 5V Or half the signal..
Do you follow me?

Last edited by nosebleedaudio; 17th November 2017 at 11:31 PM..
Old 18th November 2017
  #152
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Pollo's Avatar
 

Quote:
Originally Posted by nosebleedaudio View Post
You stated "2:1" ratio..that would mean you used the 2.5K side as the INPUT..Yes?
Yes. But I can reverse it of course.

Quote:
Originally Posted by nosebleedaudio View Post
Or did You ran the -21.0 input signal into the 600 Ohm side of the transformer?
What IM trying to determine is does the "600" ohm side when used as a input is a true 600 Ohm "LOAD" on the source driving it...
Probably not. But this is where things get confusing for me. Does it matter? Isn't the load on the secondary coil reflected to the primary, as the turns ratio squared. Maybe that doesn't mean what I think it does, but then what does it mean?

Quote:
Originally Posted by nosebleedaudio View Post
Not 100% sure I follow what you did.
Do you have a VOM?
In the circuit I posted running a 10V RMS signal into the input and measuring across the 680 Ohm resistor you SHOULD read around 5V Or half the signal..
Do you follow me?
I didn't know what a VOM is but apparently it is a multimeter. Yes I have one.
But it is only accurate to a tenth of a Volt for AC. I used an audio signal for measuring. It was 0 dB on a +4dBu reference scale. It is something like 1.3 Volt I think? Not sure. But it is a lot less then 10 Volt.
Old 18th November 2017
  #153
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Quote:
Originally Posted by Pollo View Post
Yes. But I can reverse it of course.



Probably not. But this is where things get confusing for me. Does it matter? Isn't the load on the secondary coil reflected to the primary, as the turns ratio squared. Maybe that doesn't mean what I think it does, but then what does it mean?



I didn't know what a VOM is but apparently it is a multimeter. Yes I have one.
But it is only accurate to a tenth of a Volt for AC. I used an audio signal for measuring. It was 0 dB on a +4dBu reference scale. It is something like 1.3 Volt I think? Not sure. But it is a lot less then 10 Volt.
+4dBu is 1.23V on a VOM.
Were not looking for exact numbers, just close enough to prove a point..

I used 10V for a nice round number..But it Does represent +22dBu...Or in this case dBm.
Another reason for using a VOM is its "Floating" not referenced to ground (A battery operated VOM that is)..

Your leaving out some info, your first test where you fried the outputs driving these transformers were connected in a 1:2>2:1 correct? Using the 600 Ohm secondary as the Primary?

Last edited by nosebleedaudio; 18th November 2017 at 02:02 PM..
Old 18th November 2017
  #154
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Like this:
between A & B you have for example 10V, between C & D it Should be half that or close..
Follow me?
Attached Files
File Type: doc Transformer test (2).doc (24.5 KB, 35 views)
Old 18th November 2017
  #155
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I am beginning to understand. Ok, so I did new tests. This time the kind you wanted to see. And the results are interesting in so far that it is different from what I expected.

First I measured just one transformer, with the 600 Ohm side as the primary. I used a slightly lower signal. At +21 dBu my converters clip so I couldn't go that high. But I measured 9 Volt between hot and ground so i figured it'd be close enough.

So 680 Ohm resistor in series with (supposedly) 600 Ohm transformer:
A to B: 8.6 Volt
C to D: 5.6 Volt
D to B: 4.35 Volt

Then I did the same with the 2.5 KOhm side.
So 680 Ohm resistor in series with (supposedly) 2.5 KOhm transformer:
A to B: 8.9 Volt
C to D: 2.15 Volt
D to B: 7.75 Volt

It got interesting when I put the two transformers in series.
So 680 Ohm resistor then T1 with 600 Ohm as primary followed with T2 with 2.5 KOhm as primary:

A to B: 8.55 Volt
C to D: 6.6 Volt
D to B: 2.6 Volt

Does this mean that in the last case the load seen by the output is only 338.8 Ohm? (680 / 6.6) * 2.6

I wouldn't have expected that.

Also I don't understand why the voltage between A and B is never the sum of the other two measurements. Or is that because of inaccurate measuring tools?
Old 18th November 2017
  #156
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nosebleedaudio's Avatar
 

Quote:
Originally Posted by Pollo View Post
I am beginning to understand. Ok, so I did new tests. This time the kind you wanted to see. And the results are interesting in so far that it is different from what I expected.

First I measured just one transformer, with the 600 Ohm side as the primary. I used a slightly lower signal. At +21 dBu my converters clip so I couldn't go that high. But I measured 9 Volt between hot and ground so i figured it'd be close enough.

So 680 Ohm resistor in series with (supposedly) 600 Ohm transformer:
A to B: 8.6 Volt
C to D: 5.6 Volt
D to B: 4.35 Volt

Then I did the same with the 2.5 KOhm side.
So 680 Ohm resistor in series with (supposedly) 2.5 KOhm transformer:
A to B: 8.9 Volt
C to D: 2.15 Volt
D to B: 7.75 Volt

It got interesting when I put the two transformers in series.
So 680 Ohm resistor then T1 with 600 Ohm as primary followed with T2 with 2.5 KOhm as primary:

A to B: 8.55 Volt
C to D: 6.6 Volt
D to B: 2.6 Volt

Does this mean that in the last case the load seen by the output is only 338.8 Ohm? (680 / 6.6) * 2.6

I wouldn't have expected that.

Also I don't understand why the voltage between A and B is never the sum of the other two measurements. Or is that because of inaccurate measuring tools?
One thing for sure the "600 Ohm" has less than 600 Ohms (looks like around 500), in series with the 2nd transformer looks like around 250 Ohms...if that's right..WAY too low for any IC to drive...
And yes your math does not work out, did you use a battery powered VOM?

Last edited by nosebleedaudio; 19th November 2017 at 12:45 PM..
Old 19th November 2017
  #157
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Hansest's Avatar
 

love trafos. use them all the time, most of the gear i use have at least 2. I even put some old beyers for the i/o of my plate verb and it sounds great .
Attached Thumbnails
DIY transformer box to add color-15942887_10154908219046018_148370825_o.jpg  
Old 20th November 2017
  #158
Im thinking this idea would be great as a test bench item, more so then a studio item.

Having a box with sockets/clip leads to place the transformers in with i/o to try out on different developing circuits. Then transplanting said harvested transformers to device.
Old 20th March 2019
  #159
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goom's Avatar
Anything new out there, especially on the cheap?
Old 20th March 2019
  #160
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drBill's Avatar
Quote:
Originally Posted by goom View Post
Anything new out there, especially on the cheap?
Mister Focus - RGB - Louder Than Liftoff

Load it with either API or Neve transformers / line cards - or both..... You can cascade them as well...
Old 20th March 2019
  #161
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Quote:
Originally Posted by drBill View Post
Mister Focus - RGB - Louder Than Liftoff

Load it with either API or Neve transformers / line cards - or both..... You can cascade them as well...
That's really interesting. I wonder how high quality and accurate to the original gear the transformers are. I'm not seeing them mention anything like Carnhills or Cinemags. Are they more like emulations as an effect along the lines of the JHS Colour Box? That would make the most sense given the price tag.

I feel intrigued but also a bit skeptical.
Old 20th March 2019
  #162
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drBill's Avatar
Quote:
Originally Posted by dublave View Post
That's really interesting. I wonder how high quality and accurate to the original gear the transformers are. I'm not seeing them mention anything like Carnhills or Cinemags. Are they more like emulations as an effect along the lines of the JHS Colour Box? That would make the most sense given the price tag.

I feel intrigued but also a bit skeptical.
The Mr Focus itself is pretty much just a "host" with a Tilt (focus) EQ - which IMO is worth the price of admission. Add to that the ability to both "drive"" and "blend" (mix) wet / dry signals is a necessity IMO when pushing transformers into their harmonic sweet spots. Without being able to drive your transformers and DOA's, you're missing a lot of the magic that's on tap. Parallel blending is another tool that's extremely helpful for me.

As for the line cards themselves, lots of anecdotal comments on both the Royal Blue (Neve) and Mass Drivr (API) are out there. They have been "in the wild" for quite awhile now. You can satiate your skepticism by doing a little search or checking the reviews on the above mentioned site.

IMO, the Mass Drivr is extremely punchy and vintage API-ish - more vintage than some API-ish stuff that's available. Royal Blue is fat like you would expect a Neve to be. No...it doesn't have Carnhills. But there are those out there who believe that Carnhills fall short of "the sound" of vintage Neve. Just sayin'. I know Brad's target when he was designing that transformer was more towards a vintage Marinair sound while still staying somewhat "open" on the top rather than towards a Carnhill sound. At some point, we're just parsing minute details though. BTW, both transformers are custom US wound and available only in LTL products....

Take it for what it's worth. At those prices, it's not much of a risk to experiment and check em out to see if they fit YOUR particular esthetic. My opinion is just my own, but I'm using em in a wide variety of hybrid mixing applications.


PS - the base price of the RGB model does not include either the API or Neve card(s) - those are roughly $100 ea - extra.

Last edited by drBill; 20th March 2019 at 07:46 PM..
Old 20th March 2019
  #163
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Quote:
Originally Posted by drBill View Post
PS - the base price of the RGB model does not include either the API or Neve card(s) - those are roughly $100 ea - extra.
Thanks for the thoughtful response, drBill. Definitely now on my radar!
Old 20th March 2019
  #164
I decided to make myself one of these types of tools. I had/have no soldering experience so this was a pretty fun adventure. My burn wound is almost healed now. LOL

I ordered some Cinemags and some components and went to it. I haven't tried this in every possible position in my chain, but so far it's really fun.
Yes it's subtle but it does something very nice to the low end tightness and overall presence. The knobs are just to be able to drive the transformers and then turn that signal back down as it sits in a chain.

I may post this to Reverb. We'll see.
Attached Thumbnails
DIY transformer box to add color-purple-tone.jpg  
Old 20th March 2019
  #165
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goom's Avatar
Quote:
Originally Posted by jpanderson80 View Post
I decided to make myself one of these types of tools. I had/have no soldering experience so this was a pretty fun adventure. My burn wound is almost healed now. LOL

I ordered some Cinemags and some components and went to it. I haven't tried this in every possible position in my chain, but so far it's really fun.
Yes it's subtle but it does something very nice to the low end tightness and overall presence. The knobs are just to be able to drive the transformers and then turn that signal back down as it sits in a chain.

I may post this to Reverb. We'll see.
What does it sound like at the maximum setting?
Old 20th March 2019
  #166
Quote:
Originally Posted by goom View Post
What does it sound like at the maximum setting?
It's has a tightening of the bass and a transient taming that is nice. I used Steel transformers, to try to have as much "color" as possible. The knobs are to turn the signal down, not up. So your input signal drives the transformers. It doesn't have the fancy options like some of the LTL products, but it was a fun project and I learned... which was a big goal for me.
Old 20th March 2019
  #167
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BradM's Avatar
Quote:
Originally Posted by dublave View Post
That's really interesting. I wonder how high quality and accurate to the original gear the transformers are. I'm not seeing them mention anything like Carnhills or Cinemags. Are they more like emulations as an effect along the lines of the JHS Colour Box? That would make the most sense given the price tag.

I feel intrigued but also a bit skeptical.
Hi,

Thanks for your interest. The transformers on Royal Blue and Mass Drivr are wound by a very experienced and high quality American winder that makes transformers for lots of gear people love and use daily. While Carnhill and Cinemag have name recognition to folks outside of manufacturing circles, there are some very reputable transformer manufacturers in the U.S. that make equally good sounding magnetic products and are willing to take the time to iterate on a design with a small manufacturer like myself. When developing products I always trust my ears and never settle. And that means sometimes the name brand stuff just doesn't give me what I'm looking for. As for price...if you buy enough of something the price can be quite reasonable. I buy 500 pieces of these transformers at a time so that reduces the per unit cost to something reasonable.

The circuits used in Mass Drivr and Royal are not effecty emulations in any way. They are the real deal (see the circuit descriptions on my website). By miniaturizing cirucuits wth SMT parts you can really pack a lot of mojo into a small space with intentful and meticulous design.

cheers,
Brad
Old 20th March 2019
  #168
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Quote:
Originally Posted by BradM View Post
cheers,
Brad
Thank you for the detailed response, Brad! I'll more than likely be picking one of these things up in the not so distant future!
Old 20th March 2019
  #169
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Quote:
Originally Posted by dublave View Post
Thank you for the detailed response, Brad! I'll more than likely be picking one of these things up in the not so distant future!
You're welcome. Feel free to email me directly or call (even better!) and I'd be happy to answer any questions you might have.

thanks,
Brad
Old 21st March 2019
  #170
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monkeyxx's Avatar
It's funny to read back over this thread years later.

I was looking at the Avedis TransDrive and he's got some novel features to this transformer box idea.

I can figure out a lot of it based on what he tells but what is a "common mode inductive element" and how would you wire a transformer that way?

Does anyone have any idea what this bit means? "The CUSTOM setting puts audio through two additional transformers which are small and mounted on the PCB inside. Rather than the traditional way of passing audio through it from Primary to Secondary, we use it as a common mode inductive element. What this means is that audio passing through it gets mashed up and the distortion created with peaks is natural and sounds useful. You can change the characteristics of the distortion by selecting different parallel and series ratios adjustable with the second controls."
Old 21st March 2019
  #171
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Quote:
Originally Posted by monkeyxx View Post
... what is a "common mode inductive element" and how would you wire a transformer that way?

Does anyone have any idea what this bit means?
I had a lengthy chat with Avedis (it's his first name) at NAMM and it wouldn't surprise me if he'd be willing to explain it further. Unlike some other players in the color-box game he seems to be very grounded in the science of all this and zero-BS, as is Brad M. Besides, he gave me a free tee shirt so I have to like him.
Old 21st March 2019
  #172
Deleted df98c51
Guest
If it is not primary then secondary in series, then it would be what, wired parallel perhaps.

I did my DIY transformer box up with Western Electric 111c transformers, the big ones. Used a linear taper pot for an ohms control, another for output. On XLR's.
Old 22nd March 2019
  #173
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monkeyxx's Avatar
Quote:
Originally Posted by Brent Hahn View Post
I had a lengthy chat with Avedis (it's his first name) at NAMM and it wouldn't surprise me if he'd be willing to explain it further. Unlike some other players in the color-box game he seems to be very grounded in the science of all this and zero-BS, as is Brad M. Besides, he gave me a free tee shirt so I have to like him.
I think we're friends on Facebook, he does seem like a nice enough guy, if I get curious enough I'll ask him.
Old 22nd March 2019
  #174
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monkeyxx's Avatar
Quote:
Originally Posted by mark1971 View Post
If it is not primary then secondary in series, then it would be what, wired parallel perhaps.

I did my DIY transformer box up with Western Electric 111c transformers, the big ones. Used a linear taper pot for an ohms control, another for output. On XLR's.
I think maybe the transformer in question is connected "sideways" so it's not actually a transformer any more, but a pair of inductors. One on each of the + and - audio lines ("Common mode")

I wonder if the transformer action between the + and - would mess up the signal on purpose.

I've never really heard of this before and I have no idea how it creates distortion.

Just thinking out loud here.
Old 22nd March 2019
  #175
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Quote:
Originally Posted by monkeyxx View Post
I think maybe the transformer in question is connected "sideways" so it's not actually a transformer any more, but a pair of inductors. One on each of the + and - audio lines ("Common mode")

I wonder if the transformer action between the + and - would mess up the signal on purpose.

I've never really heard of this before and I have no idea how it creates distortion.

Just thinking out loud here.
In the electronics industry, Its commonly used as a special RFI filter that addresses common mode power noise. Never seen it used commercially outside of the power supply section.
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