Okay, i think i've pretty much read every thread there is to do with passive balanced attenuators here already, and i still have some more questions.
The cheap stepped attenuators that goes on ebay such as these -> 100 kOhm Stepped Attenuators, Qty:6 - eBay (item 160419314868 end time Apr-07-10 17:41:24 PDT)
seem to, accordingly to the guys here, have the clicking sound, that's out for me. I've read some posts here that detail how a balanced setup could be done with these attenuators but it doesn't get rid of the clicking noise.
The Goldpt 4 deck stepped attenuators are just a little more than i can afford, likewise with the DACT/TKD attenuators.
I've read the threads on the lightspeed attenuator as well, but it seems like he's out of stock for a balanced config. Same deal with the joshuatree.
What other options do i have? All i need is a true balanced volume control for use with one pair of monitor speakers that will give me almost perfect channel balance at all volume levels and not exhibit any funny popping/clicking sounds when i'm changing the volume. Would that be impossible to get for say, less than USD150?
The cheap stepped attenuators that goes on ebay such as these -> 100 kOhm Stepped Attenuators, Qty:6 - eBay (item 160419314868 end time Apr-07-10 17:41:24 PDT)
seem to, accordingly to the guys here, have the clicking sound, that's out for me. I've read some posts here that detail how a balanced setup could be done with these attenuators but it doesn't get rid of the clicking noise.
The Goldpt 4 deck stepped attenuators are just a little more than i can afford, likewise with the DACT/TKD attenuators.
I've read the threads on the lightspeed attenuator as well, but it seems like he's out of stock for a balanced config. Same deal with the joshuatree.
What other options do i have? All i need is a true balanced volume control for use with one pair of monitor speakers that will give me almost perfect channel balance at all volume levels and not exhibit any funny popping/clicking sounds when i'm changing the volume. Would that be impossible to get for say, less than USD150?
My stepped attenuators do not make any clicking noise.
If the switch contacts are make before break, then there should not be any noise when adjusting the volume.
It amost suggests that the previous user was using them in a DC coupled circuit with a small offset voltage. This would produce a switch click.
If the switch contacts are make before break, then there should not be any noise when adjusting the volume.
It amost suggests that the previous user was using them in a DC coupled circuit with a small offset voltage. This would produce a switch click.
Hi,
most switched attenuators suck, because of their highish and non -constant output impedance or because of low resolution, i.e. step-number count.
A clever solution to this is a low out-impedance switched resistor network that works in bit-wise stepping. You just need 6 switches (relais) for 63 equal steps, 7 switches for 127 steps.
A complete DIY solution can be found at Eijndhoven Family Home
You may calculate the resistor values for lower output impedance or take the values of Jos. The kit already features IR-commandability, so even comfort is high
jauu
Calvin
most switched attenuators suck, because of their highish and non -constant output impedance or because of low resolution, i.e. step-number count.
A clever solution to this is a low out-impedance switched resistor network that works in bit-wise stepping. You just need 6 switches (relais) for 63 equal steps, 7 switches for 127 steps.
A complete DIY solution can be found at Eijndhoven Family Home
You may calculate the resistor values for lower output impedance or take the values of Jos. The kit already features IR-commandability, so even comfort is high
jauu
Calvin
Thanks for all the suggestions. I found these
Balance XLR 23 Step Attenuator Potentiometer 100K Log - eBay (item 290419007537 end time Apr-27-10 05:53:28 PDT)
But i'm not sure how the wiring is done for a balanced config. Any ideas?
Balance XLR 23 Step Attenuator Potentiometer 100K Log - eBay (item 290419007537 end time Apr-27-10 05:53:28 PDT)
But i'm not sure how the wiring is done for a balanced config. Any ideas?
The wiring diagram should be supplied by the vendor,it's very simple.
With that type of switch your input and output impedance will change with the position. A ladder atten. would take 8 sections instead of 4.
Google 'series', 'shunt', and 'ladder attenuator' for a better understanding.
Best, Bill
With that type of switch your input and output impedance will change with the position. A ladder atten. would take 8 sections instead of 4.
Google 'series', 'shunt', and 'ladder attenuator' for a better understanding.
Best, Bill
Thanks Bill. I did some more reading up and am still confused about the input and output impedance varying with position. What does that ultimately mean?
I came across another post here
http://www.vt4c.com/bb/viewtopic.php?p=14591&sid=c080fb38c83aa157d27fa0faa2344a94
with "As most experts here will know, an attenuator for a 'passive preamp' is a completely different problem than for inside a preamp.
In a passive setup, you have the problem of balancing (compromising) between adequate load for your source & also minimising source impedance for your power amp. 10~15kohm pot is typically what passive guys end up trying." being particularly intriguing.
So if i'm reading this right, in my case where i'm using this attenuator in between my DAC and my active monitors, i should be looking to get a 10-15K instead?
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Yes, a 10k would be the best compromise as long as your dac output impedance is not too high. You could have trouble if it has a tube output stage, but even then, most would work fine. I misspoke in my earlier post, a series att has constant input impedance and would work fine except the signal has to pass through many series resistors, especially at lower volume positions.
The ladder is the best because there are only two resistors in the circuit at any setting, but it requires two switch sections for each signal line, so an 8 pole switch is necessary for stereo balanced.
The shunt has many good qualities but it's input impedance does change, and some output circuits don't respond well. You also lose some output from the dac even turned all the way up, so that would depend on the voltage your amps need and how loud you listen. Even with these limitations, it's worth trying because it is the simpleist and most cost effective way to make a balanced att. Erno Borbely has written a bit about their use, check out his website. For stereo, all you need is 4 resistors and a dual log pot or series att switch.
Best, Bill
The ladder is the best because there are only two resistors in the circuit at any setting, but it requires two switch sections for each signal line, so an 8 pole switch is necessary for stereo balanced.
The shunt has many good qualities but it's input impedance does change, and some output circuits don't respond well. You also lose some output from the dac even turned all the way up, so that would depend on the voltage your amps need and how loud you listen. Even with these limitations, it's worth trying because it is the simpleist and most cost effective way to make a balanced att. Erno Borbely has written a bit about their use, check out his website. For stereo, all you need is 4 resistors and a dual log pot or series att switch.
Best, Bill
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We have opened a group-buy, but the interest is not so big as expected. :-(
Our passive r2r / shunt volume controller will support balanced mode as well.
http://www.diyaudio.com/forums/group-buys/158718-gb-r2r-audio-volume-input-selection-pcb.html
Regards,
Tibi
Our passive r2r / shunt volume controller will support balanced mode as well.
http://www.diyaudio.com/forums/group-buys/158718-gb-r2r-audio-volume-input-selection-pcb.html
Regards,
Tibi
The shunt has no better qualities than the ladder and has both variable input impedance as well as variable output impedance. The "advantage" of the shunt attenuator is based on the myth that the shunt resistor is less critical, and erroneously considered by some to be out of the "signal path" when in fact the voltage developed across it IS the signal.
se
Yes that is the truth !
But even with the tapper audio transformer changing the impedance in secondary does reflect in changing of input impedance , so : every passive attenuator do suffer from variable input impedance whatever circuit do you use !!!
Only active attenuator ( like this : Input --->buffer-->attenuator--->buffer--->output ) have a constant input and output impedance !!!!
..... even so the passives one are sounding so sweet .
K&K has a shunt attenuator that looks very interesting for balanced circuits. Since there is only one shunt resistor that is shared between halves, the balance is very stable and is set by the fixed series resistors.
Its on the bottom of this page K & K Audio - Lundahl Transformers, audio DIY kits and more
HTH
Doug
Its on the bottom of this page K & K Audio - Lundahl Transformers, audio DIY kits and more
HTH
Doug
An old thread I realise - thinking about this myself recently.
Shunt as described in the link in the post above does have specific advantages for balanced in that it negates the requirement of supremely matched components for both hot and cold. Get that matching slightly wrong and the balanced topology will be subtracting all sorts of bits of the signal and not just noise..
Audio Synthesis uses (used) the same shunt type for thier balanced attenuator, the ProPassion.
Essentially it becomes a blending control, blending the amount of seperation between hot and cold - the more you "attenuate" via the knob, the more the hot and cold are mixed and so cancelling each other out resulting in less of the voltage passing through
to the fixed resistors directly connected between in and out.
Shunt as described in the link in the post above does have specific advantages for balanced in that it negates the requirement of supremely matched components for both hot and cold. Get that matching slightly wrong and the balanced topology will be subtracting all sorts of bits of the signal and not just noise..
Audio Synthesis uses (used) the same shunt type for thier balanced attenuator, the ProPassion.
Essentially it becomes a blending control, blending the amount of seperation between hot and cold - the more you "attenuate" via the knob, the more the hot and cold are mixed and so cancelling each other out resulting in less of the voltage passing through
to the fixed resistors directly connected between in and out.
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