Alps potentiometer
- Thread starter RoA
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Arkless Electronics
Trade: Amp design and repairs.
The Alps Blue has been the industry standard for decades for very good reason. It has excellent channel balance for a pot, it's reliable over many years and it has a nice "feel" to it. Other than a very few, very rare, and mega expensive units for military or industrial use that a few high end companies used, there was basically nothing available other than the really crap units which were the same as fitted to TV sets, music centres, ghetto blasters etc... until the Alps Blue came along. In fact even the "music centre grade" pots from the likes of Japanese companies like Alps were in themselves MUCH better than the UK, USA and European equivalents that had been used before!
Look up the price of Noble dual gang close tolerance pots.... you'd best be sitting down when you do...
If you want better than the Alps Blue use a switched attenuator. Perfect channel balance and yes they do sound better.
Look up the price of Noble dual gang close tolerance pots.... you'd best be sitting down when you do...
If you want better than the Alps Blue use a switched attenuator. Perfect channel balance and yes they do sound better.
Jim O'Rourke
Ex-Colgate Sales Rep.
Nice story but that doesn't explain the literal bloodbath that Naim is taking over the use of these pots. Even on their own highly-moderated Community forum there are a great number of conversations and threads about this. Not everyone is happy about it, including the hardcore Naim fans.
Secondly, there could also be just a general decline in the production quality of these units from Alps and it is beginning to show.
Thirdly, Naim apparently sorts these pots for tolerance deviation and reserves the best performers for the more expensive units. The rejects are mounted in the lesser ranges. Plus, with their purchasing discount, I'm guessing they are paying about 12-15£ for the motorized versions (just my estimate).
Finally, some rocket scientist decided that combining extreme high-gain volume control with badly tracking potentiometers would be an excellent idea and they launched full-scale mass production. Can you think of a better recipe for a massive industrial fail?
Anyway, whatever.
Arkless Electronics
Trade: Amp design and repairs.
Story? It's the simple facts and from an ex industry insider and present day amplifier designer.
I've never known one of these pots to be less than "perfect" ie no obvious channel imbalance. There is nothing else I would even give a micro seconds consideration to if going for a pot rather than a switched attenuator.
I've no interest in Naim and wouldn't have anything made by them even if it was free.
John Phillips
pfm Member
Yes. If you list all of the unknown variables that a volume control has to cope with, and their possible ranges, then you certainly find you need something like that device.
I once did a spreadsheet to see if I could see a canonical gain structure for an audio system. But there's not really one. The total range of things a user can throw at his/her volume control to sort out is immense. A very good potentiometer still only just matches the most common range with reasonable precision. You really need a lot more precision over a wide range of operation, so it's no wonder to me this issue sometimes becomes a source of frustration. An electronic or a switched volume control can always be better.
However, as long as the total system gain does not commit the cardinal sin of being too low that you run out of maximum volume, you can safely adjust the operating point of a good potentiometer with attenuation, as long as the excess gain you are throwing away isn't too much.
Jim O'Rourke
Ex-Colgate Sales Rep.
Not looking to start an epic internet battle but your affirmation that you've never encountered an Alps pot that was "less than perfect" is tantamount to claiming the Pope is Buddhist. It's just not credible, but whatever.
Your statement on Naim however is one I can fully support, with perhaps the requirement that free would still be too expensive and that Naim should pay me to take one of their products.
But, no need to fight about this stuff.
Arkless Electronics
Trade: Amp design and repairs.
I repeat, I have never found an Alps Blue pot to be less than perfect. And I have professional experience of many hundreds of them. By "perfect" I mean no audible channel imbalance. Obviously it will be measurable. I also do not expect ANY pot to be used below say "1" on a 1 to 10 dial range (ideally above "2")
The only times I've had to change one is because they have become noisy after over 10 year regular use. I have not needed to change even one solitary Alps Blue due to channel imbalance in the > 30 year they have been around and very commonly see >20 year old ones still working great in equipment that comes to me for service
I will say that the last one I bought in was about 2 years ago so maybe, just maybe, they have moved production to China or some such in that time and quality control has fallen through the floor.... seems unlikely though.
Less than perfect would be greater than a 3dB variation between channels though. IMHO and alps blue can be 'perfect' but still a long way from acceptable!
They still have the nicest feel of anything in their price range, especially the motorised ones.
Jim O'Rourke
Ex-Colgate Sales Rep.
My requirement of a potentiometer does not include feeling. It relates solely to general performance, channel tracking and balance and reliability. I use the remote to change volume so I don't feel anything, except contempt for Alps potentiometers...
You sir need to try one of the old Penny & Giles oil damped rotary faders. If I had one of those on my preamp I'd make a point of changing volume by hand rather than pick up the remote! I like tactile controls.
I suspect though a lot of these issues could be 'solved' with a 20dB pad switch on the front (or rear) of the unit. And use the pot away from its extremes.
Jim O'Rourke
Ex-Colgate Sales Rep.
Hi, could you explain what a pad switch is and what an implementation would look like? Thanks.
graystoke4
pfm Member
Hi, when i had my Spectral audio, they had no pot at all, but i think a digital volume control, Arkless will know more about this than me , hear we go,
The Case for Uncompromising Attenuation
Certain devices in a high-end preamplifier fundamentally determine the ultimate performance possible in the component. Since a preamplifier basically amounts to an adjustable line amplifier, the role of the volume control or gain attenuator system is especially critical and will have a strong influence over the final sonics of the component. Most of today’s high-end preamps incorporate various digital and IC based attenuator systems to control gain, while a minority still use mechanical controls, potentiometers, switches or relay arrays. In our experience all of these approaches have serious compromises which limit signal transparency, dynamic range, step resolution or reliability. Today, digital based IC attenuators are ubiquitous in modern audio design. But even the most exotic of these digital and solid-state attenuators color the sound in various ways. Spectral engineers have long experience researching digital and DAC attenuators and find that none of these gain controls are really up to the demands of high-end preamp use, let alone for critical recording applications. We find the best relay and switch based resistor attenuators to be much better sonically than any digital control. Unfortunately, they in turn suffer from dynamic range and contact life limitations, more importantly they are not a realistic option when continuous gain adjustment is required. Since digital attenuators are not sonically transparent and stepped resistor attenuator controls have step size, contact life and dynamic range limitation, the ultimate gain control would have to be a continuously variable potentiometer or fader. Unfortunately, no pot or fader currently available is transparent or linear enough for the most critical gain adjustment applications in audio.
The Spectral Super Fader Technology
To solve the problems of existing gain control systems Spectral engineers have been working with a leading aerospace contractor. Out of this multi-year effort comes an extraordinary ultra-precision gain control. The Spectral ‘Super Fader’ combines mechanical precision, advanced materials science and unrestricted use of exotic materials to create a level control that behaves like an infinite number of theoretically ideal resistors. Inside, the critical moving parts are precision machined from solid precious metals. These wipers have many surfaces that are spring pressured as a group to contact micro-polished optically flat resistance elements. Exemplary mechanical design and fabrication alignment is used to prevent localized heating from circulating currents. Ultra-pure contact metal eliminates solid-state or junction distortions which occur from plated parts used in other controls. When such precision and material commitments are combined, noise and error in the presence of test signals is immeasurable and other performances are very near to ideal thermal accuracy limits. With polished custom element and ball-bearing construction, there is every indication that this superior performance will remain intact even after 100 million operations. The ‘Super Fader’ potentiometer outperforms all existing gain control systems with virtually infinite service life. We hear a clarity and transparency, as if a wire has been substituted for the control.
- taken off spectral's web page,
Arkless Electronics
Trade: Amp design and repairs.
Ah yes it was Penny and Giles I was thinking of when I mentioned Noble earlier! Only around £500 each!
The one time I've seen one in audio gear was in a DPA pre amp.
Arkless Electronics
Trade: Amp design and repairs.
It can be done genuinely digitally in some digital kit but what is often meant is a switched attenuator with no moving parts. Transistors or fets do the switching.
Arkless Electronics
Trade: Amp design and repairs.
An attenuator. Two resistors usually. Lowers the level so the pot is being used at say "5 - 7" rather than down at say "2" where channel imbalance will be worse.
Gervais Cote
Predator
Gosh...............really missing the large black ALPS used in older Naim NAC 32.5 and stepped ones used in vintage Quad 44.........
Can’t someone start making new versions of these ?
Can’t someone start making new versions of these ?
So it's basically as Arkless explained, but for example on a night if the kids are in bed, my Quad 34 generally is at position 2 or 3 (out of 21) on the volume, this would be -52dB and -47dB from max respectively, this would be where you have issues on your Alps I think. A 20dB pad would reduce this level subjectively in half twice (10dB is subjectively twice as loud). So you would now need to wind the volume up to 7-9 on the dial for the same volume. You have gone from the very bottom of the control to almost half way. Pads are a bit of a pro audio thing, you don't usually see them on domestic stuff. But then most pro stuff would have a switched attenuator for volume and a fine trim pot that has maybe a 6dB range to get a level exact between positions.
Arkless Electronics
Trade: Amp design and repairs.
Usual marketing bollox. Sounds like a micro-machined stepped attenuator from the very vague description.
Arkless Electronics
Trade: Amp design and repairs.
Some potentiometer porn
The unmounted one on the left obvs. Only £500 to you sir! In a DPA DSP-50S pre I had in recently.
The unmounted one on the left obvs. Only £500 to you sir! In a DPA DSP-50S pre I had in recently.