using line level impedance transformer/balun?

[alessa]

I have notice those Zaika ZLT-55A 'line level impedance tranformer' to put between CD and preamp or amps..
going for more than 1000$ in Japan:
http://www.hifido.co.jp/KW/G0304/J/0-10/C03-17911-22031-00/

It just seems to work in very high end systems..:)

Impedance matching seems important..It is to ensure the most efficient transfer of power (the audio signal) from device to device,
and a solution seems to use line level impedance transformer/balun..
I am using a tube preamp that has a impedance tranformer build in with the input, and the sound seems to be much better than other tube pre-amps i ve got..

So I generally have devices with output impedance of 10, 47, 75, 200 Ohm..
and devices with input impedance of 1.5K, 2K, 20K, 31K, 50K, 1M Ohm...

So does anyone know which cheap line level impedance transformer to buy or how to make these DIY...?:blink:

[Allanvh5150]

I have notice those Zaika ZLT-55A 'line level impedance tranformer' to put between CD and preamp or amps..
going for more than 1000$ in Japan:
http://www.hifido.co.jp/KW/G0304/J/0-10/C03-17911-22031-00/

It just seems to work in very high end systems..:)

Impedance matching seems important..It is to ensure the most efficient transfer of power (the audio signal) from device to device,
and a solution seems to use line level impedance transformer/balun..
I am using a tube preamp that has a impedance tranformer build in with the input, and the sound seems to be much better than other tube pre-amps i ve got..

So I generally have devices with output impedance of 10, 47, 75, 200 Ohm..
and devices with input impedance of 1.5K, 2K, 20K, 31K, 50K, 1M Ohm...

So does anyone know which cheap line level impedance transformer to buy or how to make these DIY...?:blink:

There is no such thing as a cheap matching transformer. As long as you have a low impedence source driving a high impedence input you should not have any issues. If you want to match you gear exactly it is easier and cheaper to use active. The results can often be far superior as well.

Allan.

[JoMoCo]

Altec matching transformers and others are commonly used in MC / mic signal matching as well as other preamp inputs. Transformer companies have product with a wide variety of application some of which may be what you are looking for...:hmm:



Check these out for diy ideas or questions

http://www.10audio.com/bob's_devices_step_up.htm

http://www.bobsdevices.com/photos.htm

[alessa]

If you want to match you gear exactly it is easier and cheaper to use active. The results can often be far superior as well.

Allan.
can we get really better sound maching gears impedance?

and what kind of devices can we use for "active" impedance matching?:blink:

[Beowulf57]

General points:

1. Impedance matching is important in networks, output transformer/speaker configurations and long signal lines where optimum power transfer is necessary. As all hams know: gotta keep that SWR low or a lot of your power is reflected right back at ya.

2. MC transformers are voltage step-up devices.

3. CD players and preamps are not "power" devices, they are voltage amplifiers and in general all you want is a low output impedance feeding a high input impedance. For example a 2 volt output from a CD player (with say a 500 ohm output impedance) feeding a 10,000 ohm preamp input impedance will have to source 0.2 milliamperes of current and the whopping output power required is 0.4 miiliwatts. You do not need impedance "matching" in this situation.

4. Output transformers are necessary in most tube amplifiers (which are voltage amplifiers) to match the very high output impedance of the tube to the very low impedance of the speaker. The tube cannot source the current reuqired by the speaker directly, except in the case of OTL (Output Transformer Less) designs which use multiple tubes in parallel to reduce the output impedance and source the required current.

[Mike Caldwell]

Hello

It sounds like your looking for a DIY project! Jensen transformers are considered among the best and on their website under the "Schematics" section they offer several schematics for consumer and pro applications.
http://www.jensen-transformers.com/


Have fun
Mike Caldwell

[Eaulive]

General points:

1. Impedance matching is important in networks, output transformer/speaker configurations and long signal lines where optimum power transfer is necessary. As all hams know: gotta keep that SWR low or a lot of your power is reflected right back at ya.

2. MC transformers are voltage step-up devices.

3. CD players and preamps are not "power" devices, they are voltage amplifiers and in general all you want is a low output impedance feeding a high input impedance. For example a 2 volt output from a CD player (with say a 500 ohm output impedance) feeding a 10,000 ohm preamp input impedance will have to source 0.2 milliamperes of current and the whopping output power required is 0.4 miiliwatts. You do not need impedance "matching" in this situation.

4. Output transformers are necessary in most tube amplifiers (which are voltage amplifiers) to match the very high output impedance of the tube to the very low impedance of the speaker. The tube cannot source the current reuqired by the speaker directly, except in the case of OTL (Output Transformer Less) designs which use multiple tubes in parallel to reduce the output impedance and source the required current.

:applaud:

I couldn't say it better. The rest is, again... snake oil.

[jcrobso]

:applaud:

I couldn't say it better. The rest is, again... snake oil.

Be careful of the FUD!!:blink:


"So I generally have devices with output impedance of 10, 47, 75, 200 Ohm..
and devices with input impedance of 1.5K, 2K, 20K, 31K, 50K, 1M Ohm..."
This is the way it should be.

Back in the tube days the only practical way to have balanced lines was to use a transformer.
Today there are other ways to get a balanced input and output.

[Eaulive]

Be careful of the FUD!!:blink:


"So I generally have devices with output impedance of 10, 47, 75, 200 Ohm..
and devices with input impedance of 1.5K, 2K, 20K, 31K, 50K, 1M Ohm..."
This is the way it should be.

Exactly! Anyways some of these components when loaded at their "rated" impedance _like 100ohms or less_ don't have the output devices to handle the current draw and power dissipation and will often saturate and sound like sh*t.

I remember a "pseudo" PRO CDplayer by teac in the 1980s, the XLR outputs started saturating when loaded at 200 ohms!

[Ruediger]

see Douglas Self's site: http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm for another source of information.

Ruediger

[andywin]

The use of transformers between CD and amps (pre & power) has been popular in Japan for a long time. Many big name companies like Luxman, Sony etc. have produced them.

The theory is that inserting transformers "softens" the sound of CD therefore giving a more analogue sound.

Western Electric 111C & 119C transformers are popular choices for the DIY route. I have a pair of 119C transformers that I have wired to enable switchable balanced / SE inputs and outputs. I have tried them between a CD and pre and they do make a harsh sounding player more euphonic. Whether this is hi end stuff is debatable.

http://www.jtw.zaq.ne.jp/cfaax409/Westernelctricaudio11111.html

http://www.westernlabo.com/45_625.html

[Beowulf57]

The theory is that inserting transformers "softens" the sound of CD therefore giving a more analogue sound.

Western Electric 111C & 119C transformers are popular choices for the DIY route. I have a pair of 119C transformers that I have wired to enable switchable balanced / SE inputs and outputs. I have tried them between a CD and pre and they do make a harsh sounding player more euphonic. Whether this is hi end stuff is debatable.

http://www.jtw.zaq.ne.jp/cfaax409/Westernelctricaudio11111.html

http://www.westernlabo.com/45_625.html

I suspect we are speaking of the use of a transformer/inductor as a filter for HF garbage that is inadequately dealt with in the low pass filters used in harsher sounding CD players.

[jcrobso]

The use of transformers between CD and amps (pre & power) has been popular in Japan for a long time. Many big name companies like Luxman, Sony etc. have produced them.

The theory is that inserting transformers "softens" the sound of CD therefore giving a more analogue sound.

Western Electric 111C & 119C transformers are popular choices for the DIY route. I have a pair of 119C transformers that I have wired to enable switchable balanced / SE inputs and outputs. I have tried them between a CD and pre and they do make a harsh sounding player more euphonic. Whether this is hi end stuff is debatable.

http://www.jtw.zaq.ne.jp/cfaax409/Westernelctricaudio11111.html

http://www.westernlabo.com/45_625.html
Make it sound more analog, maybe by rounding off the leading edge of a transient wave???

But over the years the digital to analog converts got much better as did the analog filtering. If you have a hash sound CD player toss it and get a better one.
At the radio station 98% of my signals are over balanced lines, this is necessary in this environment, long cable runs, many cables running tight together over long runs, etc.

[Eaulive]

Everything is relative...

From Yorkville sound: (http://www.yorkville.com/default.asp?p_id=72)

Audiophile signal processing (Analog) - Really expensive esoteric rackmount effects processors designed to reduce tape hiss, eliminate tape saturation, reduce wow and flutter and clean up any tube distortion in the signal path during the analog (tape) recording process. Thus making the final product much more pristine and therefore better sounding to the listener.

Audiophile signal processing (Digital) - Really expensive esoteric rackmount effects processors and software plug-ins designed to emulate tape hiss, and tape saturation, induce wow and flutter and create tube distortion in the signal path during the digital recording process, thus making the final product much less pristine and therefore better sounding to the listener.

:applaud::applaud::applaud:

[alessa]

The use of transformers between CD and amps (pre & power) has been popular in Japan for a long time. Many big name companies like Luxman, Sony etc. have produced them.

The theory is that inserting transformers "softens" the sound of CD therefore giving a more analogue sound.

This is also my experience with my Tube preamp that has a impedance transformer, it sound way more lively and dynamic than the one without and i've grown quite found of it. :p
That's why i'd really like to replicate this device.

[Ruediger]

This is also my experience with my Tube preamp that has a impedance transformer, it sound way more lively and dynamic than the one without and i've grown quite found of it. :p
That's why i'd really like to replicate this device.

Transformers will not soften Your sound. They will produce distortions when overdriven but that would take away the freedom to adjust the volume for the right loudness.

Look for products which do TSE (Tape Saturation Emulation) or products from www.soundperformancelab.de (http://www.soundperformancelab.de). They give You that Vodoo sound. Some of them use DSPs :)

Ruediger

[Beowulf57]

This is also my experience with my Tube preamp that has a impedance transformer, it sound way more lively and dynamic than the one without and i've grown quite found of it. :p
That's why i'd really like to replicate this device.

Are these two tube preamps identical except that one uses an input transformer ( not a step-up transformer I assume: 1:1?) and the other does not? What are the input impedances of the two preamps? Just want to be sure we're talking about a transformer effect. Also, the output voltage capability of your source and the gain of the preamp will affect the "dynamics." Are the gains of the two preamps identical?

We are getting a bit far from the forum's content area...

[Eaulive]

We are getting a bit far from the forum's content area...

This thread was in the wrong forum since the beginning anyways :D

[Chas]

Back in the eighties, I remember Ed Meitner was advocating the use of transformers between pre and power amps. I think Museatex (where he worked in Montreal, at the time) even sold them for a while.

Of course, this was well before balanced lines came into vogue in consumer systems. Not that the two things are related. Or maybe they are with regard to CMRR?

[Eaulive]

Of course, this was well before balanced lines came into vogue in consumer systems. Not that the two things are related. Or maybe they are with regard to CMRR?

I don't think transformers and CMRR are related in any way. A transformer can sometimes reduce noise due to its isolating properties but not because it provides any common mode rejection.

CMR is provided by having signal or opposite polarities travel the same path through the same cable-interconnect-field of interference so the similarities of the noises picked up are easy to cancel at the receiving end. The path may or may not include transformers.

[jcrobso]

If you go back to the first post and go the link the unit has RCA jacks, not balanced!

[Ruediger]

I don't think transformers and CMRR are related in any way. A transformer can sometimes reduce noise due to its isolating properties but not because it provides any common mode rejection.

CMR is provided by having signal or opposite polarities travel the same path through the same cable-interconnect-field of interference so the similarities of the noises picked up are easy to cancel at the receiving end. The path may or may not include transformers.

The purpose of (input) transformers is a high CMRR, that's what they are good for. See the technical papers at Jensen transformers.

Ruediger

[jcrobso]

The purpose of (input) transformers is a high CMRR, that's what they are good for. See the technical papers at Jensen transformers.

Ruediger

They can be hooked up balanced or unbalanced, CMRR only happens in the balanced configuration.

I find it interesting, one of the goals over the years in amp design to get the "straight wire with gain" was to eliminate transformers from the signal path.
I have a mixer board at the station that is around 20 years old it has transformers on the inputs and outputs to keep things balanced.
I also have a new state of the art computerized DSP digital mixing board the has balanced ins and outs, no transformers! This board sounds great, cost $50,000 so it should.
My take on transformers is that if you NEED them use them.

[Eaulive]

The purpose of (input) transformers is a high CMRR, that's what they are good for. See the technical papers at Jensen transformers.

Ruediger

Here we go again.

No, input transformers have no influence on CMRR. Common mode rejection is made possible by the transmission line configuration, the processing at the receiving end may or may not be a transformer.
Modern equipment have a very high CMRR and do not use transformers.

If you use standard unbalanced RCA cable, your equipment's input stage can have the highest CMMR and all the transformers in the world, no common mode rejection will occur.

I suggest you read too ;)

[Eaulive]

They can be hooked up balanced or unbalanced, CMRR only happens in the balanced configuration.

Exactly, assuming the line is balanced as well of course.

[Ruediger]

Here we go again.

No, input transformers have no influence on CMRR. Common mode rejection is made possible by the transmission line configuration, the processing at the receiving end may or may not be a transformer.
Modern equipment have a very high CMRR and do not use transformers.

If you use standard unbalanced RCA cable, your equipment's input stage can have the highest CMMR and all the transformers in the world, no common mode rejection will occur.

I suggest you read too ;)

This gets silly.

http://www.jensen-transformers.com/an/ingenaes.pdf

http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm

In the latter paper look for "impedance balanced output".

Ruediger

[Eaulive]

This gets silly.

http://www.jensen-transformers.com/an/ingenaes.pdf

http://www.dself.dsl.pipex.com/ampins/balanced/balanced.htm

In the latter paper look for "impedance balanced output".

Ruediger

So, where did I say this was not true? :blink:
I agree that english is not my mother tongue but still...

[alessa]

Cool, i opened the tube preamp that sounded good, and got the transformer spec:
it's a OEP A262CAN SCRN (screening can)
http://www.canford.co.uk/ProductResources/ig/2739.pdf
I can't really understand what it does..:blink:
but as it is cheap, maybe it's worth a buy to test it with power amps, or other preamps..?

[Ruediger]

Cool, i opened the tube preamp that sounded good, and got the transformer spec:
it's a OEP A262CAN SCRN (screening can)
http://www.canford.co.uk/ProductResources/ig/2739.pdf
I can't really understand what it does..:blink:
but as it is cheap, maybe it's worth a buy to test it with power amps, or other preamps..?

What kind of input connector does the preamp have? What do You connect to it and how is that wired?

Ruediger

[alessa]

What kind of input connector does the preamp have? What do You connect to it and how is that wired?

Ruediger

It's got XLR input, i connect the balanced output of my Soundcard RME fireface 800, it is wired in balanced stereo jack to XLR..:)

[Ruediger]

It's got XLR input, i connect the balanced output of my Soundcard RME fireface 800, it is wired in balanced stereo jack to XLR..:)

Please do check the resources given in post #27.

Two different “base levels” are in use:

0 dBu: 0.775 V RMS, this would be 1 mW into a 600 Ohm load
0 dBV: 1.00 V RMS

Pro Equipment uses one of these levels:

+4 dBu: 1.23 V RMS. standard pro level
+6 dBu: 1.55 V RMS. non-standard pro-level

Your soundcard supplies a (too?) high level at Full Scale level in the digital section (dBFS):

Input/Output Level @ 0 dBFS @ Hi Gain: +19 dBu
Input/Output Level @ 0 dBFS @ +4 dBu: +13 dBu
Input/Output Level @ 0 dBFS @ -10 dBV: +2 dBV

The transformer gets into saturation @ 0 dBu:

Distortion: <1% at: 100mW @ 300Hz, 1mW @ 30Hz

It can not handle the pro levels, resp. it will generate heavy distortion,
and You can very easily overdrive it with Your soundcard.

The transformer is of low quality and will be overdriven by most "audiophile" CD players, also by most consumer CD players.

Ruediger