Hi everybody and merry Christmas. 🙂
I want to replace the volume pot on my tube pre with a stepped attenuator. I almost decided it to be a shunt type Elma, Seiden or Khozmo. I need to determine the stepping now.
Previous owner replaced the stock 50K log pot with an Alps 100K. I don't know the reason behind it but maybe he simply had only a 100K pot at the moment. With this pot my listening range of the volume knob is extremely narrow: Only between 7 - 8 o'clock. Am I right assuming that the reason behind this, is the 100K pot instead of 50K? I think going back to 50K will enlarge this range to 10-11 o'clock?
Since my potentiometer gives no clue about my listening levels, I need a reference to determine the stepping and attenuation range. Is dB ranges in devices universal? I have a A/V receiver which digitally displays the volume level as dB's. According to my AVR my listening range is between -36dB to -26dB. And I rarely go down -50dB range and go up -15dB range. Is it ok to make the stepping between -50dB to -10dB?
Any suggestions between Elma/Seiden/Khozmo?
Regards
I want to replace the volume pot on my tube pre with a stepped attenuator. I almost decided it to be a shunt type Elma, Seiden or Khozmo. I need to determine the stepping now.
Previous owner replaced the stock 50K log pot with an Alps 100K. I don't know the reason behind it but maybe he simply had only a 100K pot at the moment. With this pot my listening range of the volume knob is extremely narrow: Only between 7 - 8 o'clock. Am I right assuming that the reason behind this, is the 100K pot instead of 50K? I think going back to 50K will enlarge this range to 10-11 o'clock?
Since my potentiometer gives no clue about my listening levels, I need a reference to determine the stepping and attenuation range. Is dB ranges in devices universal? I have a A/V receiver which digitally displays the volume level as dB's. According to my AVR my listening range is between -36dB to -26dB. And I rarely go down -50dB range and go up -15dB range. Is it ok to make the stepping between -50dB to -10dB?
Any suggestions between Elma/Seiden/Khozmo?
Regards
From Potentiometer to Steeped Attenuator
Hi,
100K pot in my unit is an Alps Blue Velvet. I'm not sure if it is a log or linear pot.
Hi,
100K pot in my unit is an Alps Blue Velvet. I'm not sure if it is a log or linear pot.
Adjust the pot to it's mid point and measure the resistance from the slider to each end. If it's a linear pot, the resistances will be similar. If it's a log pot, the resistances will be vastly different.
With the attenuator, I would give it full control. From full attenuation to no attenuation.
I would not limit the range.
With the attenuator, I would give it full control. From full attenuation to no attenuation.
I would not limit the range.
Hi Frank, I haven't make any measurements (I'm novice at electronics) but an internet searched give me that it is a log pot.
So, changing it to a 50K pot gives me a more broader range on the knob?
Regards.
PS: A "steeped" attenuator? Not likely, maybe a stepped attenuator.
So, changing it to a 50K pot gives me a more broader range on the knob?
Regards.
PS: A "steeped" attenuator? Not likely, maybe a stepped attenuator.
It shouldn't make that much difference. Older tube preamps are more sensitive. Line levels are much higher today than they were 40 or 50 years ago.
I would consider your AVR decibel readings as pretty arbitrary unless you actually measure it to confirm its operation.
Unless you know the actual gain of your tube preamp it will also be simply guessing what your step levels are actually producing.
So, if you want to be sure, measure both units.
Unless you know the actual gain of your tube preamp it will also be simply guessing what your step levels are actually producing.
So, if you want to be sure, measure both units.
IMO, better You can use att. 10 -20 kohm, but no more.../If You will use 100 k., on small volume, upper part with big resistance will decrease, IMO, quality and dynamic of input current.../
Some thing would help answer your question . 1. what are the preceding and post circuits around the volume control ? 2. source levels . Different tube like different volume controls where a 6gk5 is happy with a 20k pot the 12ax7 has problems with less than 50k .
why not give it a quick try. 100k resistor in parallel with your 100k pot and you will have 50k. if its not good remove the resistor
Putting a resistor in parallel with a pot only changes the load seen by the preceding stage. It does nothing to change the output impedance of the pot which is being used to drive the next stage. Therefore, this test is not likely to give a conclusive result.
However, in the absence of measurements, I suspect that the current pot may turn out either to be linear or faulty based upon the reported volume change response when the control is used..
However, in the absence of measurements, I suspect that the current pot may turn out either to be linear or faulty based upon the reported volume change response when the control is used..
- Status
- Not open for further replies.