I wanted to buy some Dale RN resistors for a ladder attenuator I am building. I intended to buy resistors close to the ideal resistance value of each step of the ladder, but some of the more obscure values I need are either unavailable or only available in the expensive 0.1% precision, low ppm variety. This got me thinking about alternatives and how much they would affect the sound of the amp I intended to use the attenuator for.
One of my systems has a B1 and I usually listen with the 25k pot set at the 12 o'clock position. With the B1's volume pot at mid point, I assume I throw away about half the signal coming from the digital front end.
I have thought of the following experiment to determine if I can hear the difference between different resistors. I intend to change the B1's volume to maximum and achieve the signal reduction by placing a 24k resistor in series with the input signal (between the digital front end and the B1). The total input impedance will increase (to 49k) but the digital front end should be fine with this.
I intend to use:
One of my systems has a B1 and I usually listen with the 25k pot set at the 12 o'clock position. With the B1's volume pot at mid point, I assume I throw away about half the signal coming from the digital front end.
I have thought of the following experiment to determine if I can hear the difference between different resistors. I intend to change the B1's volume to maximum and achieve the signal reduction by placing a 24k resistor in series with the input signal (between the digital front end and the B1). The total input impedance will increase (to 49k) but the digital front end should be fine with this.
I intend to use:
- 24 step rotary switch https://www.aliexpress.com/item/Free-shipping-New-1pc-2-Pole-23-Step-Rotary-Switch-Attenuator-Volume-Control-Pot-Potentiometer/1852994715.html
- Dale 24k resistor on position 1 as reference
- Various brands and types of 24k resistor on position 2, 3, 4, … for comparison. (I have ordered 12 different 24k resistors (x2) from Mouser who will probably not be very happy with this order
)
Logarithmic Attenuator Calculator
Jos van Eijndhoven has build his own volume controller (with published design for non commercial use). I think it suits your need.
He also made a resistor calculator in case you prefer to use your own volume controller
Jos van Eijndhoven has build his own volume controller (with published design for non commercial use). I think it suits your need.
He also made a resistor calculator in case you prefer to use your own volume controller
Think you need to use a good switch as variable contact resistance may destroy the result. Also I think there will be no audible difference between quality resistors. You need to make another person control the switch and you write down how you think it sounds and the "switch controller" sets the switch randomly.
I have self my doubt if it is worth the money to go from a $20 ALPS blue velvet to a $300 stepped attenuator.
I have self my doubt if it is worth the money to go from a $20 ALPS blue velvet to a $300 stepped attenuator.
Thanks for your comments. I think I need to clarify a few things.
I have built stepped attenuators before using discrete Dale resistors. Fiddly work, but they work fine. I never compared them to the Alps pots in my drawer so do not know if they sound the same. I do know that different caps can affect the sound of a system and wondered about resistors.
Currently I am building a remote controlled attenuator.
I have the boards and software etc. for an 8 bit ladder attenuator, just waiting for me to order the parts. The design is similar to the one in the Aleph AP1.7. It can be remote controlled, which is an absolute requirement for me.
I have calculated the values I need for a 25k attenuator and by graphing the attenuation know the range of values of a given resistor for relatively even spaced transitions. Some values are easy to get (in or close to E24 range) but some Dale resistors of the values I need are only available in .1% with low ppm. These are expensive. I can buy cheap metal film (different brands) for a fraction of the price but have no idea if I will hear the difference. That is the reason for my experiment. Will I be able to hear a difference?
I have 12 different 24k resistors on order. Most are metal film but I included a metal oxide and a few carbon ones as well to see if I can tell the difference.
Although I agree that an expensive switch would be more appropriate to find small differences, I am hoping that the difference in resistors will be greater than the differences due to switch positions. If there is no difference to be heard, I can eliminate the switch and use headers or something similar to put resistors in the signal path. If I still can't hear a difference I will be buying cheap resistors in future!
I have built stepped attenuators before using discrete Dale resistors. Fiddly work, but they work fine. I never compared them to the Alps pots in my drawer so do not know if they sound the same. I do know that different caps can affect the sound of a system and wondered about resistors.
Currently I am building a remote controlled attenuator.
I have the boards and software etc. for an 8 bit ladder attenuator, just waiting for me to order the parts. The design is similar to the one in the Aleph AP1.7. It can be remote controlled, which is an absolute requirement for me.
I have calculated the values I need for a 25k attenuator and by graphing the attenuation know the range of values of a given resistor for relatively even spaced transitions. Some values are easy to get (in or close to E24 range) but some Dale resistors of the values I need are only available in .1% with low ppm. These are expensive. I can buy cheap metal film (different brands) for a fraction of the price but have no idea if I will hear the difference. That is the reason for my experiment. Will I be able to hear a difference?
I have 12 different 24k resistors on order. Most are metal film but I included a metal oxide and a few carbon ones as well to see if I can tell the difference.
Although I agree that an expensive switch would be more appropriate to find small differences, I am hoping that the difference in resistors will be greater than the differences due to switch positions. If there is no difference to be heard, I can eliminate the switch and use headers or something similar to put resistors in the signal path. If I still can't hear a difference I will be buying cheap resistors in future!
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