Hi Guys, can anyone recommend a high quality volume control or potentiometer for a Valve DAC output signal. That way I can avoid to use a pre-amplifier and control the output right there in a DAC.
Is there anything better than ALPS 27 ?
Many Thanks
Mykhailo
Is there anything better than ALPS 27 ?
Many Thanks
Mykhailo
What resistance value do you need? A switched resistor type would work well, but they can be costly.
Quite a few people find costly stepped attenuators made from rotary switches and 1% tolerance metal film resistors to be "icy cold". On the conductive plastic front, Penny & Giles offer controls said to be outstanding, but the price will give you cardiac arrest.
Good sounding, very well made (milspec tough), and modestly priced are the KA (mono) and KKA (stereo) hot molded carbon controls by PEC of Canada. DigiKey is the go to North American distributor. I don't know which distributor a UK resident should order from.
BTW, regardless of the control(s) you settle on, unless the cabling between DAC and power amplifier is short and very low capacitance, a buffer (voltage follower) driving the cables is very much in order.
Good sounding, very well made (milspec tough), and modestly priced are the KA (mono) and KKA (stereo) hot molded carbon controls by PEC of Canada. DigiKey is the go to North American distributor. I don't know which distributor a UK resident should order from.
BTW, regardless of the control(s) you settle on, unless the cabling between DAC and power amplifier is short and very low capacitance, a buffer (voltage follower) driving the cables is very much in order.
Most DACs will happily drive a 10K potentiometer. Even with 2 metres of 100pF/m cable attached, this will only be 3dB down at over 300KHz.
Cheers
Ian
I've tried Alps, PEC and Neohm pots, stepped attenuators and autoformer volume controls and much prefer the autoformers. Slagle autoformers were my choice; more expensive than a pot but in my opinion worth it.
I've tried them all.
For the money, either law-faked wire wound 10 turn or the PEC linear pots are hard to beat.
Switched attenuators start out all good and well, but can be cold as ice as stated and, in my experience, the switches don't hold up over time. I don't use them as a result - namely Elma switches. That said there are some good switches but you might as well buy a remote Slagle former with their cost.
Davens can be good but good luck finding them these days, not to mention the cost has become outrageous IMO.
Some decade and half or so ago, I was one of the first to try Dave Slagle's autoformers. I current use a remote controlled version in my reference system. I've never look back and nothing has ever beaten it sonically to my ears.
For the money, either law-faked wire wound 10 turn or the PEC linear pots are hard to beat.
Switched attenuators start out all good and well, but can be cold as ice as stated and, in my experience, the switches don't hold up over time. I don't use them as a result - namely Elma switches. That said there are some good switches but you might as well buy a remote Slagle former with their cost.
Davens can be good but good luck finding them these days, not to mention the cost has become outrageous IMO.
Some decade and half or so ago, I was one of the first to try Dave Slagle's autoformers. I current use a remote controlled version in my reference system. I've never look back and nothing has ever beaten it sonically to my ears.
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Try a LDR attenuator. http://www.diyaudio.com/forums/anal...d-ldr-volume-source-selection-controller.html
Ian,
The O/P was talking about putting the volume control(s) in the DAC, not the DAC driving a passive control center.
Then the O/P should buy a ES9018 Sabre DAC, which comes with the best possible attenuator: an internal 48 bit digital volume control.
I once used a Tocos Cosmos carbon pot in a pre and was very pleased. The channel tracking was good and the build quality is also thumbs up.
You should get those in the UK for little more than 20 GBP.
You should get those in the UK for little more than 20 GBP.
Since I tried rotary type attenuators I never went back to film types. I can't speak about autoformers, haven't tried yet. Both types, conductive plastic and carbon are inferior compared to a rotary switch, at least the ones I lived with.
People used to make such switches with tantalum resistors, mainly because of the accuracy they present. Low thermal noise, crystal clear sonics and great stability but yes, they are cold, icy cold, hence they don't belong to audio. Might be good for missiles but not for audio. I have made stepped and ladder atennuators with simple metal films and they are fine. Furthermore a ladder type presents only 2 resistors in the signal path, so it can't do much harm.
Here is an attenuator that I have and also it has balance control in case you need it.
LITE AUDIO V03
And an other choice you should consider: if you're DAC is kind of obsolete, you could go to an other one with built in digital control and discard the pot, but this way you'll have an all over digital center.
Cheers!
People used to make such switches with tantalum resistors, mainly because of the accuracy they present. Low thermal noise, crystal clear sonics and great stability but yes, they are cold, icy cold, hence they don't belong to audio. Might be good for missiles but not for audio. I have made stepped and ladder atennuators with simple metal films and they are fine. Furthermore a ladder type presents only 2 resistors in the signal path, so it can't do much harm.
Here is an attenuator that I have and also it has balance control in case you need it.
LITE AUDIO V03
And an other choice you should consider: if you're DAC is kind of obsolete, you could go to an other one with built in digital control and discard the pot, but this way you'll have an all over digital center.
Cheers!
Hi,
I will need either 250K or 500K Stereo type attenuator or volume control for a custom made tube Pre-Amplifier.
Have a look please if these are good choices (anything below £60 if fine with me);
When you add to "Buy Now" button you will have a choice to choose stereo type and other additional options.
1). Glasshouse Takman 0.5W Carbon film Shunt Stepped Attenuator
Glasshouse Takman 0.5W Carbon film Shunt Stepped Attenuator | Hifi Collective
2). Glasshouse Stepped Attenuator, 0.5W PRP metal film resistor, Shunt version
Glasshouse Stepped Attenuator, 0.5W PRP metal film resistor, Shunt version | Hifi Collective
and
3). Khozmo Stereo Series Stepped Attenuator
Khozmo Stereo Series Stepped Attenuator, 48 step | Hifi Collective
There is also well known Alps 27 version potentiometer, would anyone know if Alps 27 has copper contacts or signal path?
Have so far worked with two variants
LOW COST: 1. TKD CP601 rotary potentiometer (better than that of ALPs)
High End: Auto Transformer Volume Control (AVC) from Intactaudio 28 Steps
LOW COST: 1. TKD CP601 rotary potentiometer (better than that of ALPs)
High End: Auto Transformer Volume Control (AVC) from Intactaudio 28 Steps
This pot will be in series with the internal resistance of your source and this is what your tube sees in conjunction with the Rgk. So, unless it is a buffer, a 47-100K pot would be more suitable, if I'm not wrong.
For less than $100, best ones are the RK40 (discontinued though, hard to find any value more than 50K these days) and TKD 2CP2511. Most of the good stepped attenuators are more than $150 for a stereo unit. But 250K or 500K? Are you sure that is what you are really looking for?
Hi, I will need to chose either to go with stepped-attenuators or potentiometer for example TKD 2CP-2500 Series which has 250 and 500K options. I can not go below 250K as it will put a negative load on active tubes in pre-amplifier. As I understand TKD 2CP-2511 rotary potentiometer has a gold plated internal parts where signal passes, although I can not find any information whether the gold plating on brass or other metals such as copper. Now another option is Glasshouse Takman stepped attenuator (Glasshouse Takman 0.5W Carbon film Shunt Stepped Attenuator | Hifi Collective) woukld you think considering its parts could it be a better option?
The Glasshouse Takman in your link is just a standard Chinese switch, bunch of them on eBay. The TKD pot is probably your best bet.
Sounds like your output is not designed to drive cables and/or normal Receivers.
Get a new output stage, or add on a Buffer stage, that can drive cables etc.
Hi Andrew, As a tube designer (with 20+ years of experience) explained to me, he said that potentiometer desirably should have 500K resistance. This in turn will effect sound quality in his active valve pre-Amp design. The lower resistance the more stress placed on tubes. Of course the output from valves can be adjusted but it is desirable in his High-End design.
If the tube/valve stage has a high output impedance then it is normal for these to require a very high load impedance.
But that is not the end of it.
They also need ultra low capacitance and that is not so easy.
The solution is to convert the tube/valve output to low impedance and that makes it capable of driving normal impedance loads. And if the current capability is also improved it will tolerate the capacitance of the cables.
But that is not the end of it.
They also need ultra low capacitance and that is not so easy.
The solution is to convert the tube/valve output to low impedance and that makes it capable of driving normal impedance loads. And if the current capability is also improved it will tolerate the capacitance of the cables.