ALPS RK271-series volume pot (10 kΩ, audio taper; Mouser P/N: 688-RK27112AS-103)
I ordered the Alps pot from RS Components to Hamilton Canada.
The pot plus delivery came to $30.37 USD
The duty came to $20.06 CAD
Mouser wouldn't have the pot in stock till April. I ordered from RS Components so I could get the 20mm version. I'm pleased I don't have to take a hack saw to the pot but I didn't expect the duty.
Either way I'd though I'd give the head's up to any Canadian builders thinking of ordering that part...
I ordered the Alps pot from RS Components to Hamilton Canada.
The pot plus delivery came to $30.37 USD
The duty came to $20.06 CAD
Mouser wouldn't have the pot in stock till April. I ordered from RS Components so I could get the 20mm version. I'm pleased I don't have to take a hack saw to the pot but I didn't expect the duty.
Either way I'd though I'd give the head's up to any Canadian builders thinking of ordering that part...
I sure didn‘t. Sorry if it came across that way, I was taking for granted that this was a cardinal sin never to be committed and surprised you even felt the need to mention it. I now see how one could read that post differently. Mea culpa
I ordered 50 of those from RS recently. Paid CAD $11 to DHL for the customs processing and $48.39 CAD in GST (5% as I'm in Alberta). Seems pretty reasonable on a $1k+ order...
You can double-check the paperwork from DHL, but it's probably the processing fee that bit you.
One way to avoid the processing fee is to use FedEx and set up an account with them. You can have the customs fees charged to your account and the shipping fees to the vendor's account (they likely get a much better deal than you do). That eliminates the $10 brokerage fee that FedEx charges. FedEx does tend to be more expensive than DHL, though.
Alps must be really backed up in their production. I ordered 500 custom RK271 pots (through a distributor) in September and have yet to receive any word on when they'll ship. They quoted 2-3 months lead time at the time.
Tom
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I did it in small clamp (vise), as in:
Clamping Sockets on Ribbon Cable (with Pictures) - Instructables
I described my method in the HP-2 design doc. Basically:
A small vise, such as the one linked to above, works well too. I used to have one of those, but it wasn't the greatest quality, so I tossed it when I moved across the Atlantic.
It takes a little practice to make the cable, but it shouldn't be too bad - even for a first-timer. You can gently pry the connector apart (lift the ears, then pry) and often reuse them if you mess up. The BOM includes enough ribbon cable for two tries.
Tom
- Feed the ribbon cable through the IDC connector.
- Make sure the cable is aligned properly within the little 'forks' that form the connection with the wire and that Pin 1 of the connector aligns with Wire 1 of the cable.
- Press down on the top piece of the connector with the bottom of the connector resting against a hard surface (top of lab bench). I press with the heel of my hand with some hard object in between to ensure constant force across the connector.
- Ensure the top piece is pressed fully down. You should get an audible 'click' from the "ears" of the top piece as they lock in place.
- Fold the cable over and attach the strain relief.
- Repeat for the opposite end of the cable. Make sure the connectors are aligned properly with the cable.
A small vise, such as the one linked to above, works well too. I used to have one of those, but it wasn't the greatest quality, so I tossed it when I moved across the Atlantic.
It takes a little practice to make the cable, but it shouldn't be too bad - even for a first-timer. You can gently pry the connector apart (lift the ears, then pry) and often reuse them if you mess up. The BOM includes enough ribbon cable for two tries.
Tom
What is a "Reference" Amp?
Below is a summary of my first few months with the Neurochrome HP-2.
It’s no secret that I am a fan of Tom’s methodology and his products. This will not be a review per se, but an explanation of how the HP-2 found its way into my daily-driver position for desktop headphone listening and why I now consider it a “reference” headphone amp.
Background
I got the amp from Tom at the Burning Amp Festival in November. I had asked Tom about buying a set of boards for the HP-1. He had discontinued the HP-1 boards, but he offered to sell me his prototype HP-2, so I gladly agreed. My unit was built by Tom with carefully selected parts, but no “boutique” parts. The total budget to build a comparable unit is less than $500 USD using the same excellent case and well-chosen parts. You can also build it for much less. This is a DIY project, so everyone’s mileage and budget will vary.
I’m a bit of a subjectivist. That’s not because I don’t trust measurements, but because I have very little idea how to interpret much of the data. I know certain measurements and specs tie to whether an amplifier is well-designed, but I have no clue what makes things sound good (to me).
My primary use for the HP-2 is as a desktop amp for use while I work. So my main comparisons were with other desktop amps; namely the Lyr 3, a Crack with Speedball, the WHAMMY, and the ACP+. Tubes, opamps and other accessories were not “rolled” and were not a factor. I compared the amps as I would use them normally.
I used the amp almost daily. I did some casual A/Bs with a reasonable number of amps and DAC/Amp combos. I generally listen to gear over an extended period of time vs. back and forth A/Bs.
I used Sennheiser HD 800S, Sennheiser HD820, Meze Classic, Oriolus IEMs, and Beyerdynamic Xelento for comparisons. I use the Sennheisers at my desk most often. So, naturally, they got the most use, but I also wanted to see how it would perform with lower impedance headphones and IEMs.
The vast majority of listening was done with a MacBook Pro feeding a variety of DACs, but primarily I used a Topping DX7s over USB connected to the balanced inputs of the HP-2 with standard XLRs. No fancy cables. I use Audirvana or Roon to access my personal storage and Qobuz. I use Audirvana because I like using Can Opener and Sonarworks occasionally.
When listening to the various amps and comparing them, occasionally I’d listen for a song or two and sometimes for a half song or less trying to compare known passages. I would level match by ear to the best of my ability when comparing amps for shorter sessions. However, most of the time I’d hook up an amp and listen for ½ a day or more and up to a week in a few cases. Except when consciously A/Bing I used the amps as I normally would without writing down any notes or really thinking much about them. I listen to a broad range of music at what would probably be considered soft levels, but I like to listen at higher volumes on occasion. I pay attention to all aspects of the music, but I place a lot of weight on vocals.
Summary
The HP-2 is my primary “reference” headphone amp. It is also now my primary amp for desktop listening. I thought a lot about how I’d describe it, and why I’d use it more on my desktop compared with other gear I own. First, what do I mean by reference? It will be one of the amps I will use to compare other amps to in the future. It will also be one of the amps I’ll use to compare headphones and sources.
Why? It works well with all my music and all my headphones. Also, I’m not one for using audiophile terms, but it is remarkably “revealing”. When I changed something in the chain, the HP-2 seemed to make the change more discernable. If I changed out a DAC or a pair of headphones, it seemed easier for me to hear the differences.
Why is it on my desktop? Today, there are remarkably great measuring amps, and also many that add a little special sauce or maybe have a “house sound”. To me, it does not matter much. There are those that think amps should be a “wire with gain” and those that just want what sounds best to them. I lean more toward what sounds best to me. However, when an amp works well and sounds great along with matching up to exceptional specifications; I’m a happy guy.
What I like about the HP-2 –
• Balanced inputs.
• Switchable gain. I use Sonarworks along with clipping protection, so it helps to have more gain when my signal is attenuated 12dB
• Exceptionally “revealing” sound, particularly in the treble.
• Detail in the lower registers. Bass seems accurate and tight, revealing the timbre of the instruments. This applied to even my low impedance HPs.
Other comments -
• I may add an external gain switch. After all, this is DIY
• I may add an XLR output at some point. As Tom notes, this does not make the amp balanced, but I primarily use headphone cables terminated with XLR.
• It’s unforgiving of some recordings. But really, I’m not sure if amps should be “forgiving”.
Below is a summary of my first few months with the Neurochrome HP-2.
It’s no secret that I am a fan of Tom’s methodology and his products. This will not be a review per se, but an explanation of how the HP-2 found its way into my daily-driver position for desktop headphone listening and why I now consider it a “reference” headphone amp.
Background
I got the amp from Tom at the Burning Amp Festival in November. I had asked Tom about buying a set of boards for the HP-1. He had discontinued the HP-1 boards, but he offered to sell me his prototype HP-2, so I gladly agreed. My unit was built by Tom with carefully selected parts, but no “boutique” parts. The total budget to build a comparable unit is less than $500 USD using the same excellent case and well-chosen parts. You can also build it for much less. This is a DIY project, so everyone’s mileage and budget will vary.
I’m a bit of a subjectivist. That’s not because I don’t trust measurements, but because I have very little idea how to interpret much of the data. I know certain measurements and specs tie to whether an amplifier is well-designed, but I have no clue what makes things sound good (to me).
My primary use for the HP-2 is as a desktop amp for use while I work. So my main comparisons were with other desktop amps; namely the Lyr 3, a Crack with Speedball, the WHAMMY, and the ACP+. Tubes, opamps and other accessories were not “rolled” and were not a factor. I compared the amps as I would use them normally.
I used the amp almost daily. I did some casual A/Bs with a reasonable number of amps and DAC/Amp combos. I generally listen to gear over an extended period of time vs. back and forth A/Bs.
I used Sennheiser HD 800S, Sennheiser HD820, Meze Classic, Oriolus IEMs, and Beyerdynamic Xelento for comparisons. I use the Sennheisers at my desk most often. So, naturally, they got the most use, but I also wanted to see how it would perform with lower impedance headphones and IEMs.
The vast majority of listening was done with a MacBook Pro feeding a variety of DACs, but primarily I used a Topping DX7s over USB connected to the balanced inputs of the HP-2 with standard XLRs. No fancy cables. I use Audirvana or Roon to access my personal storage and Qobuz. I use Audirvana because I like using Can Opener and Sonarworks occasionally.
When listening to the various amps and comparing them, occasionally I’d listen for a song or two and sometimes for a half song or less trying to compare known passages. I would level match by ear to the best of my ability when comparing amps for shorter sessions. However, most of the time I’d hook up an amp and listen for ½ a day or more and up to a week in a few cases. Except when consciously A/Bing I used the amps as I normally would without writing down any notes or really thinking much about them. I listen to a broad range of music at what would probably be considered soft levels, but I like to listen at higher volumes on occasion. I pay attention to all aspects of the music, but I place a lot of weight on vocals.
Summary
The HP-2 is my primary “reference” headphone amp. It is also now my primary amp for desktop listening. I thought a lot about how I’d describe it, and why I’d use it more on my desktop compared with other gear I own. First, what do I mean by reference? It will be one of the amps I will use to compare other amps to in the future. It will also be one of the amps I’ll use to compare headphones and sources.
Why? It works well with all my music and all my headphones. Also, I’m not one for using audiophile terms, but it is remarkably “revealing”. When I changed something in the chain, the HP-2 seemed to make the change more discernable. If I changed out a DAC or a pair of headphones, it seemed easier for me to hear the differences.
Why is it on my desktop? Today, there are remarkably great measuring amps, and also many that add a little special sauce or maybe have a “house sound”. To me, it does not matter much. There are those that think amps should be a “wire with gain” and those that just want what sounds best to them. I lean more toward what sounds best to me. However, when an amp works well and sounds great along with matching up to exceptional specifications; I’m a happy guy.
What I like about the HP-2 –
• Balanced inputs.
• Switchable gain. I use Sonarworks along with clipping protection, so it helps to have more gain when my signal is attenuated 12dB
• Exceptionally “revealing” sound, particularly in the treble.
• Detail in the lower registers. Bass seems accurate and tight, revealing the timbre of the instruments. This applied to even my low impedance HPs.
Other comments -
• I may add an external gain switch. After all, this is DIY
• I may add an XLR output at some point. As Tom notes, this does not make the amp balanced, but I primarily use headphone cables terminated with XLR.
• It’s unforgiving of some recordings. But really, I’m not sure if amps should be “forgiving”.
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What power supply are you using? 28W 1A wall brick or so thing more complex?
Just want to know - I’m planning adding a hp2 to a soekris 1941 directly using the balanced out. The soekris will run on it’s own power 5V and the hp2 on a 12V 1A.
Headphones I have currently are 55ohm hence the 1941 will be a little quiet attempting drive them directly.
Just want to know - I’m planning adding a hp2 to a soekris 1941 directly using the balanced out. The soekris will run on it’s own power 5V and the hp2 on a 12V 1A.
Headphones I have currently are 55ohm hence the 1941 will be a little quiet attempting drive them directly.
Fantastic. Thank you for sharing! I'm glad you like the HP-2.
12 V, 1 A is a bit skimpy for the HP-2. The recommended supply is 28 V, 25 W, though you could go with a 15-20 W model if you wanted to.
Tom
