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Old 19th February 2008, 05:27 PM   #1
kvk is offline kvk  United States
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Question www.diykits.com.hk stepped volume control ... any good?

Anyone know if this volume control is any good?

For $14 shipped, the price sure ain't bad.

I know you have to solder in 48 Rs but this is DIY after all.

Link -> http://www.diykits.com.hk/volume_control.htm


They also have a dual mono but any reason not so just use stereo? I figure sit in the middle if you want the speakers at the same volume.

Here's a pic of the unit minus the Rs--

Click the image to open in full size.
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Old 19th February 2008, 05:37 PM   #2
giulio is offline giulio  United Kingdom
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Hi,

re the switches alone I use them for two pairs of TX102 transformer volume controls They have replaced two Elma switches. I am very happy with them, they are very smooth which cannot be said of the Elma (which are also known to develop contact problems).

If you cannot afford Selden go for them! I cannot comment on the resistors but they look rather cheap.

g
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Old 19th February 2008, 06:01 PM   #3
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Hi Giulio

can you tell how long you have been using your switch? I read some repports (I think from Peter Daniel) that those models also presented contact problems after a while. Peter Daniel was using the ready to use versions, built with Dale resistors.

Erik
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Old 19th February 2008, 07:04 PM   #4
poynton is offline poynton  United Kingdom
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I bought one of these through Ebay.

No soldering details were included and the seller said he did not have them.


http://cgi.ebay.co.uk/VOLUME-CONTROL...QQcmdZViewItem

Now the listing says no manual etc.

So........Check first?



I also bought this - saves wiring but a little more money !!!

http://cgi.ebay.co.uk/ws/eBayISAPI.d...%3D4%26ps%3D42


Andy
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Old 19th February 2008, 08:38 PM   #5
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by poynton
I bought one of these through Ebay.

No soldering details were included and the seller said he did not have them.


http://cgi.ebay.co.uk/VOLUME-CONTROL...QQcmdZViewItem

Now the listing says no manual etc.

So........Check first?



I also bought this - saves wiring but a little more money !!!

http://cgi.ebay.co.uk/ws/eBayISAPI.d...%3D4%26ps%3D42





Andy


That's strange because I bought two, and while I would not say the provided diagram was all that clear I was able to figure it out. For $9 I have low expectations, they will either be used in infrequently used equipment and in an application where the level will be set and not frequently changed.

I figure the mediocre resistors are still likely to be better than the resistive elements in comparably priced pots.

I have several step attenuators with the elma switches and I have had some problems, all but one resolved by periodically tightening the screws that hold them together.
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Old 19th February 2008, 09:02 PM   #6
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I bought one of these - and am pretty happy with it. Seems very neutral and the switch is reasonably smooth - although in my case I have a heavy knob on it which does make it smoother. Beats an alps pot anyway. This one is quite a low profile so is good for use in a tight spot. I just love the look of the "normal" ones with all the resistors though.


ebay link


So you pays yer money and you takes your chances.

Fran
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Old 19th February 2008, 09:24 PM   #7
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by kevinkr




That's strange because I bought two, and while I would not say the provided diagram was all that clear I was able to figure it out.
Could you do me a favour and email me a copy of the diagram? (if you stil have it)

andydotathertonatyahoo.co.uk

thanks
andy
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Old 19th February 2008, 11:01 PM   #8
kvk is offline kvk  United States
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Shouldn't this chart give you the info you need? You might need to check which contacts are open/closed in a couple positions but once you know that, the list of R values should do it...

Click the image to open in full size.
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Old 19th February 2008, 11:16 PM   #9
arnoldc is offline arnoldc  Philippines
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$9 + $5 shipping?! Wow! I want one
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Old 20th February 2008, 04:22 AM   #10
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by kvk
Shouldn't this chart give you the info you need? You might need to check which contacts are open/closed in a couple positions but once you know that, the list of R values should do it...

Click the image to open in full size.
Exactly what I have on paper, this is much better. Spliting the switch into two separate blocks of 4 rows you have the following:

The outer row is the input row, "R1" the next row has just two pins which can be tied together is the first wiper row the next row is the ground row, "R2" and the final row of 2 is the other wiper row.. The pattern then repeats.

The pins in row 1 & 3 that line up with the lefthandmost pins in rows 2 & 4 are the 0 position when switch is fully ccw. (Measure to confirm.) The two sets of wipers need to be connected together to work and this signal then goes to the input of the pre-amp or amp.

Note that there is a strong reflection off of the surface this attenuator was photographed on which makes it look like there is a fifth row of resistors - there isn't.

Incidentally there is another better way to do this if you think about it. Apply input to first wiper, wire R1 resistors from first to third row, and third row resistor R2 to ground buss. Take output off of wiper in row 4.. Instead of driving all of the contact capacitance, two sets of long wipers and all of the resistors simultaneously you drive just one resistor pair, this should lower input capacitance significantly. It will not look as nice and is harder to do as well.
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