Thanks Claude
Is there an easy (temporary) fix such as adding a resistor to GND that would make the pot act like a 10k?
How do those Chinese manufacturers make this stuff so damn cheap?
I can't even get a box for the price of a finished item!!
Is there an easy (temporary) fix such as adding a resistor to GND that would make the pot act like a 10k?
How do those Chinese manufacturers make this stuff so damn cheap?
I can't even get a box for the price of a finished item!!
Add a resistor from each wiper to ground. The taper will change and you'll have to turn up
the knob higher. Start with around 10k and see how well it works. Use less than 10k if possible.
the knob higher. Start with around 10k and see how well it works. Use less than 10k if possible.
Thanks Rayma I checked the cable, seems its not available in the uk at present.
I use Cable Talk Monitor 3 interconnects can't find any info on them, probably too old now.
I bought the whole system 2nd hand about 11 years ago.
Always found it overly bright, re-worked the xovers and replaced tweeters, still a bit bright on some cds but the passive takes the damping effect a bit too far.
It did seem to increase bass a bit but thats never been an issue.
Do you feel point to point with silver cable would have any benefit when replacing the stock pot or just swap the pot and try?
I use Cable Talk Monitor 3 interconnects can't find any info on them, probably too old now.
I bought the whole system 2nd hand about 11 years ago.
Always found it overly bright, re-worked the xovers and replaced tweeters, still a bit bright on some cds but the passive takes the damping effect a bit too far.
It did seem to increase bass a bit but thats never been an issue.
Do you feel point to point with silver cable would have any benefit when replacing the stock pot or just swap the pot and try?
If you are the experimenting type, start with the pcb and just solder the side
of each terminal so it's easy to unsolder without damage. Try it out for a while,
and then next try the wires. Keep the two channels wiring apart a bit.
Hard to say how the two will compare, but pcb is usually a poor dielectric.
Or just go with the wires, it should be fine.
of each terminal so it's easy to unsolder without damage. Try it out for a while,
and then next try the wires. Keep the two channels wiring apart a bit.
Hard to say how the two will compare, but pcb is usually a poor dielectric.
Or just go with the wires, it should be fine.
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Is there any way to know for sure you are getting a genuine pot?
Seems to be a lot of fakes around.
HIFI Collective in the uk keep stock of alps 27s, they obviously have a rep to hold however they could also be buying direct from China.
Appears some faked kit is as good as the original
Seems to be a lot of fakes around.
HIFI Collective in the uk keep stock of alps 27s, they obviously have a rep to hold however they could also be buying direct from China.
Appears some faked kit is as good as the original
For the sake of shipping its probably best £4£ to just order the cable, after all its only input, output and GND the cables are only >100mm may as well get some fancy RCA's lol
Check the hole size, some may not fit and you would have to drill out the existing holes.
If its a genuine RK16 I believe the 27 is a drop in.
I'll order some cable anyway so the pcb will be redundant.
I'll order some cable anyway so the pcb will be redundant.
Your power amp has a 680pF input capacitor, forming a low pass filter with the source resistance, in worst case 1/4 the pot value modified by, not exactly accurate but closely enough, the 34Kohm amp input resistance.
A passive volume control design should take that LPF into consideration in deciding the value of the pot, so that the LPF response would not significantly alter the overall audio band frequency response. A 10K pot would put a cutoff frequency at about 100kHz (again worst case scenario), resulting in less than 0.2db attenuation at 20kHz. In comparison a 50Kohm pot will put 3dB attenuation at 20kHz.
I would not go with anything greater than 10Kohm in your case. I would not go with anything lower than 4.7Kohm either, to avoid heavily loading upstream line level device, CD player, DAC...
As far as the type of pot goes, I prefer linear, or B type, taper pot to audio taper ones. B type pots generally are better in tracking between the gangs, especially in lower volume range which usually is used most of the time. Linear taper can be easily modified to mimic audio taper by attaching a shunting resistor at its wiper. This resistor can be in the range 20% - 30% the resistance value of the pot. For a 10Kohm pot, use a 2.2K or 2.7K resistor. Note this shunt resistor pushes the LPF cutoff towards the higher frequency while increases the loading by roughly 100% to the upstream device, it can be a good alternative to use a 20Kohm B type pot and a 4.7Kohm shunt resistor if loading the upstream is a concern.
This piece by Keen talks about the taper mod.
I plotted taper mods with the shunt resistor in 10% -- 30% range.
A passive volume control design should take that LPF into consideration in deciding the value of the pot, so that the LPF response would not significantly alter the overall audio band frequency response. A 10K pot would put a cutoff frequency at about 100kHz (again worst case scenario), resulting in less than 0.2db attenuation at 20kHz. In comparison a 50Kohm pot will put 3dB attenuation at 20kHz.
I would not go with anything greater than 10Kohm in your case. I would not go with anything lower than 4.7Kohm either, to avoid heavily loading upstream line level device, CD player, DAC...
As far as the type of pot goes, I prefer linear, or B type, taper pot to audio taper ones. B type pots generally are better in tracking between the gangs, especially in lower volume range which usually is used most of the time. Linear taper can be easily modified to mimic audio taper by attaching a shunting resistor at its wiper. This resistor can be in the range 20% - 30% the resistance value of the pot. For a 10Kohm pot, use a 2.2K or 2.7K resistor. Note this shunt resistor pushes the LPF cutoff towards the higher frequency while increases the loading by roughly 100% to the upstream device, it can be a good alternative to use a 20Kohm B type pot and a 4.7Kohm shunt resistor if loading the upstream is a concern.
This piece by Keen talks about the taper mod.
I plotted taper mods with the shunt resistor in 10% -- 30% range.
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Yes it does (with a series 1k resistor), so a 10k pot is definitely the best choice
Wow, guys thank you for the amount of work gone into your posts.
I've already ordered the pot, alps 10k blue, I understand its logarithmic not linear.
I've ordered from HIFI collective so should be a legit alps product.
If the input cap and series resistor are part of the cause of the LP filter, can the values be changed to improve things a little without detriment to other circuits in the chain?
A 50k pot pushing 3db @ 20khz is similar to attenuating a crossover and would fit with what I heard.
0.2db I'm sure would be virtually inaudible for my aged hearing.
I've already ordered the pot, alps 10k blue, I understand its logarithmic not linear.
I've ordered from HIFI collective so should be a legit alps product.
If the input cap and series resistor are part of the cause of the LP filter, can the values be changed to improve things a little without detriment to other circuits in the chain?
A 50k pot pushing 3db @ 20khz is similar to attenuating a crossover and would fit with what I heard.
0.2db I'm sure would be virtually inaudible for my aged hearing.
You could reduce the 680pF to say 220pF or 100pF instead.
Use high quality capacitors, COG/NPO or polypropylene, with short leads.
Use high quality capacitors, COG/NPO or polypropylene, with short leads.
Thanks Rayma
Sorry to be so green here.
The only caps at 680pf with 1k resistors nearby would be C603,6024 and resistors R601,602?
If the caps are the ones listed they are 680pf PP is that polypropylene.
When I think of poly caps I think of those huge beasts in crossovers!
COG/NPO being ceramic caps?
Also how does lowering the value achieve lower overall capacitance and are there possibilities of other effects elsewhere along the line?
Sorry to be so green here.
The only caps at 680pf with 1k resistors nearby would be C603,6024 and resistors R601,602?
If the caps are the ones listed they are 680pf PP is that polypropylene.
When I think of poly caps I think of those huge beasts in crossovers!
COG/NPO being ceramic caps?
Also how does lowering the value achieve lower overall capacitance and are there possibilities of other effects elsewhere along the line?
Yes, pp capacitors can be large, but these are low voltage and small uF value capacitors.
For example, this pp capacitor is 0.283" L x 0.177" W (7.20mm x 4.50mm).
https://www.digikey.com/en/products...g-draloric-bc-components/KP1830122015/5392519
This ceramic capacitor is 0.142" L x 0.091" W (3.60mm x 2.30mm)
https://www.digikey.com/en/products...raloric-bc-components/K221J10C0GH53L2/2821662
The 680pF is part of an input low pass filter to reduce RF noise. You aren't likely to have a problem with
moving the corner frequency upward a bit, but it will increase the HF audio bandwidth when combined
with the output resistance of the volume control.
For example, this pp capacitor is 0.283" L x 0.177" W (7.20mm x 4.50mm).
https://www.digikey.com/en/products...g-draloric-bc-components/KP1830122015/5392519
This ceramic capacitor is 0.142" L x 0.091" W (3.60mm x 2.30mm)
https://www.digikey.com/en/products...raloric-bc-components/K221J10C0GH53L2/2821662
The 680pF is part of an input low pass filter to reduce RF noise. You aren't likely to have a problem with
moving the corner frequency upward a bit, but it will increase the HF audio bandwidth when combined
with the output resistance of the volume control.
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It's a little late now, but the Schiit SYS passive attenuator uses a 10k ALPS pot internally, and costs $50 US.
https://www.schiit.com/products/sys
https://www.schiit.com/products/sys
Thanks Rayma
Vishays seem rather elusive over here but Wima FKP2 are available.
Would the resistor value also need to be changed?
Vishays seem rather elusive over here but Wima FKP2 are available.
Would the resistor value also need to be changed?
Thank you and yes thats the product that got me thinking in the first place. The only issue being $30 shipping a couple of weeks and probably vat+import taxes to add.
There are passives available for around the £80-100 mark here but its a lot to lose if it simply wasn't compatible with the system.
This way I get to try and play, if it works out its just over £50 I'll get close to that on a resale.