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작성자 DHTsound
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다음 내용은 아래 사이트에 나온 내용을 카피한 것입니다.
http://www.penguinlovers.net/audio/Attenuator.html
 

(Note:  This is a translation of the page in http://www.diyzone.net/article.php?sid=369 and it is owned and copyrighted by www.diyzone.net.  Use it as a reference only!)  
DZ Stepping Volume Attenuator is now Available
Published Wednesday, August 27 @ 00:40:07 CST by ericchu

There are many kinds of volume control Variable Resistor (VR) available in the market, such as the Metallic Film, Carbon, etc.  If it is use on the volume control for the Stereo system (2-channels and up), it will requires at least with dual control or more (deck).  Because of the manufacturing process and it's mechanical tolerance that it may have during the making, for example, in one of my case I use one of the local made 10KA Carbon VR for the test, while one deck is at 5K level, the other deck is at 4.2K.  With this minor resistance changes, it may cause an imbalance in the stereo's volume output.   This imbalance may also cause a soundstage shift and blurring the sonic image.
  A high quality VR needs to have a tighter tolerance range.  As in the common example of an ALPS RK27112A (Blue Square shape), its tolerance is +/- 3db and the ALPS RK40312A has the tolerance of +/-2dB.  I used to have one TKD (Tokyo Ko-On Denpa) 2P2511 that has a even smaller tolerance.  I use the multimeter to measure it and it only has about 1% tolerance.  That's why the high quality VR nomally demands a higher premium and also the quality of the resistor material also affects the sonic quality.
Stepping Attenuation -- A hard to reach item
How about the Stepping Attenuation, if we are to look for a precision control?  In the past, I have purchased a GoldPoint Serial Type 24 imported by DZ and it costs me a chunk of $3,000+ NTD (Taiwan dollar, about $90 USD).  This one uses the ELMA channel selector body and German's 1% Metallic film resistors.  At that time, as I was just buying it for my hobby, I didn't know that their is a difference in different types of the stepping attenuation like the Serial type, Shunt type and the Ladder type.  After I purchased it, I later found out that the Ladder type will cost even more that $6,000 NTD (About $180 USD)!  It is too expansive for me....
The high cost does has its reason!  What a Stepping Attenuation can bring is a more precise control with a lower tolerance in resistance.  At the same time, it can also utilize the advantage of a high quality resistor's material that produces less distortion to the sound itself.
The common types of a Stepping Attenuator are:

Serial Type
It uses the resistor in series.  The advantage of this is that it only requires one deck (layer) of each channel selection and the input impedance can be kept in constant.  The disadvantage of this is that the signal (sound) path pass through a "series" of resistors and may cause a higher noise level!


Shunt Type
The signal path only pass through two resistors.  It also requires one deck (layer) for each channel selection.  The drawback of this application is that its input impedance is a variant.  Its input impedance will be higher when the resistor value increase!



Ladder Type
The signal path only pass through two resistors.  In theory, it has the lowest noise and the input impedance is stable.  However, it requires 2 decks (layers) for each channel and therefore, the quantity of resistors used is double when compare to the Serial type.  And the other drawback is its higher cost.  


DZ picks the superior Ladder Type Design

After our brief introduction of the different designs of the Stepping Attenuator, you should be able to find out that the Ladder type is the best in all the characteristics and it's disadvantage is the higher price!  Now, DZ has prepare the affordable Ladder type Stepping Attenuator kit for everyone.  The kit includes a sealed 24-positions, 4 decks attenuator.  All the contacts are silver plated and incorporated the so-called "Make before Break" to reduce the switching noise.  The resistor we pick are the military grade, Dale RN60D, 1% precision resistor.  This really is a great combination for the serious hobbyist!  Most importantly, the cost is kept affordable!  How can an item like this not making one felt excited!  


Please allow me to do a simple demonstration of how to make this new DZ Ladder type attenuator, that has 92 resistors and almost 200 soldering points, step-by step.

1.  Count your parts.  I printed out all the resistor values into two A4 (Letter in US) sheets (details I will describe it at the bottom of this article).  I put each resistor in each paper grid.  This will make the later soldering much easier!  The correct number of resistors is 92.  If you miss any, please contact DZ right away and they will send you the missing piece.  If you have more than it should, that's your bonus!  There is also the Attenuator body, one sand-blasted Aluminum knob that came with the kit.  

2. Make a wire in circle to solder the resistors.  I use a bare copper wire (using pure silver wire is even better).  I use the 1.6mm solid copper wire that I already have at hand and make a 57mm diameter circle.  The simple tool to make it into the desired circle is the plastic Coke  bottle, which is about the same diameter size.  (Translator Note: The two ends should overlap for about 10 mm) At one end, bend a 15mm wire for connection to the body.  You will need four of these rings.  

3. Make sure the direction of each position (or step):  As shown in the figure above, face the shaft toward you and count the pin clockwise.  The position starts from 1 to 24.  Make sure this sequence when you start soldering the resistor.  Do not make the mistake; otherwise, you will encounter trouble later....


4. Do it from the bottom up.  You need to do each deck by sequence from the bottom up.  The gap between each deck is very small, it will be hard if you do the other way....

5. Beware the Rin、Rg deck connection: This attenuator has 4 decks for a Stereo (Dual-) channel usage.  That means each channel will have 2 decks to connect to and each channel will have both Rin deck and Rg deck.  Therefore, if we counted from the bottom up are: 「 Rg」->「Rin」->「Rg」->「Rin」.  Of course we can also use it as 「Rin」->「Rg」->「Rin」->「Rg」, as long as each channel has both Rg and Rin deck.  Using this alternative deck is more of a enjoyable in cosmetic and easier for soldering.


The connection starts with the Rg deck from the bottom.  The connection is connect the bended wire to the connector No. 1.  Then solder the Rg resistors from No. 2 to the end, using the resistors already lying on the sheet.


For the Rin deck, it is doing the opposite.  You populate the 1~23 positions with resistor and the final 24 position, you solder it with the bended wire.  

6 Solder a 3-point connection first.  As in figure shown above, first you solder the 3-point, No. 1, 12 and 24.  This will help not only to fix the circular wire in place, but also will assist you in resistor soldering.  


7. After several hours of hard work, like building a house one story at a time, I have completed the job, as shown above.  It is an amazing structure, isn't it!  After finish this, I bet you will feel some sort of an achievement!

How to use your Stepping Attenuator?
Connect the IN to input signal, GND to ground and OUT to output signal, as shown in the figure.  Each channel's Rg and Rin should be connected together in order to function properly.  (Blue letter in photo below: the OUT connector is almost hidden...)


You can also set your resistor value to your desire
The kit DZ provided is set to 10K value.  If you would like to play around with other resistor value or for your other channel's volume control, then how should one decide his/her resistor value?  In here, we have provided a simple programming tool to help you do that.  You can set your desired condition and then calculate the resistors you need.  It is simple and fast.  This is different than the Excel spreadsheet you normally will find in the Internet.  This program provides you with an user-friendly interface and has a unique function to match the available resistor value in the market.  This will reduce the time for you to find the correct and proper resistor.  You are welcome to use it on-line.  If you find any error by using it, please give us your comment and feedback.  Thanks.
Calculating the Resistor value for Stepping Attenduator (This is the program in Chinese)

(Translation inside the program:

Setting the Resistor value

Resister value

W (ex:「10Kplease input10000)

Positions:

position(s)

Type

Ladder Type  Serial Type

Attenuation

- dB (You can use default value)

Correction:

Automatically select the market available resistor value

 

Result:


Designed by Eric Chu in 2003 Version 1.2    Any error advice welcome E-mail meThanks
End of translation)

Making a Stepping Attenuator for Volume VR is not that difficult, but will need some hard work, time and a challenge to your soldering skill!  I look forward that you can also enjoy having a Stepping Attenuator of you own!

DZ Stepping Attenuator Volume Control Installation Reference Data
DZ Stepping Attenuator Parts List(WORD Format)

DZ Stepping Attenuator Volume Control VR Kit Program
If you are a Hi-End audio fan, then you definitely are familiar with the superb performance of a Stepping Attenuator.  Even though its outstanding performance, its price is also very expansive; especially when you equip it with the imported military grade resistor on it and the price will shoots up and let people hesitate to buy one!
To fulfill the dream of DIYer, DZ has specially prepare this Stepping Attenuator kit.  This kit adopts the widely accepted Ladder Type structure.  It's signal attenuation only pass through two military grade resistor, in any volume level.  It has the benefits of short signal path, low noise and it is quite perfect!

The kit includes a sealed 24-positions, 4-decks control.  All the contacts are silver plated and incorporated the so-called "Make before Break" to reduce the switching noise.  The resistor we pick is the military grade, Dale RN60D, 1% precision resistor.   Most importantly is the price is kept affordable!  How can you not felt excited about it!
Note: This kit has impedance of 10K.  You can also use it to replace 100K、50K or 10K volume control VR.

I want to buy DZ Stepping Attenuator! (Sand-blasted Alum knob included)


Supplement to the Article(Eric Chu)
由 LIMIN-WU 於 Thursday, August 28 @ 12:02:40 CST
  http://www.diyzone.net/
This Stepping Attenuator's resistor value is based on GoldPoint's recommended value.  The reason we use it is because it has been examined through our listening evaluation and found it is smooth.  After I look at the chart I realized that pin No. 24 is not connected and available positions only up to 23.  For this reason, during our process of making one, when turning to the maximum, the attenuation is -3 db and it is almost to the full volume (many speaker's has a Frequency Response of +/- 3 db).  I think in reality, we seldom use it up to the maximum volume (some system may have distortion before that point!).  The normal usage is open the volume to about 12 o'clock position and below.  In this, we do have a smooth volume control and does not affect the sonic quality.  However, if you really like to gain this 3 db back (which is not really that necessary), this is how you can do it: 1. Jump the pin 23 and 24 together in each deck.
2. Take the No. 23 resistor in the Rg Deck, which has the value of 6.8K.

Using this two steps, you can easily gain the full output volume.  This is only for your reference.
Editor Notes: The above is only for your reference.  We still recommend user install it according to the original design.  You do not have to do the above two steps, because the one merely use that kind of volume setting.   As a matter of fact, if you have a need to use such high volume, either your are using a low pre-amp or your gain is too small!
Some reader asked who not make the Attenuator to a full 24 positions?  This is because if we make a full 24-positions, the body will have a "Full-revolutional" design.  When you turn to the 24th position, the next one will be the 1st position again and on and on.  This is not a natural instinct to our human nature in using it.

一 As mentioned by Eric Chu, DZ's Stepping Attenuator is based on widely used Gold Point resistor value in the design.  We feel this is most reliable and stable design.

Translator's Note:
The photos below are other examples of how you can make your Stepping Attenuator.  For your reference.



 
 
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