Machining an Audio Company

We build amazing headphone amplifiers and DACs. Obviously, this niche market appeals to owners of nice headphones. More interesting is a look at Google Trends for the search phrase “headphones”:

Google Trends - Headphones

It’s clear that headphone popularity has grown in the past 3-4 years (and the average consumer searches for Beats by Dre…). Easy to explain is the annual spike in headphone interest around the December holiday season, followed by a return to normal interest by summer.

Since interest in headphones directly correlates to interest in headphone amps and DACs, we’ve learned to use summer for two things:

  1. Building our company
  2. Enjoying the summer!

Upgrading our Office

We moved into a 950 sq. ft. office in May 2012. We knew orders were growing at 300% annually in 2011, and hoped that our 2012 office would be large enough to last for 1-2 years. We ran out of space in 3 months. Our inventory room was packed full, our soldering benches were feet away from our CNC machine (noisy and messy), our shipping station doubled as an assembly table, and we had no room for additional desks in our front office. Our product display table and couch turned into a lunch table and conference “room” for visitors. We even resorted to storing an engine hoist in our restroom. At least the rent was low!

We began looking for a larger facility as soon as the 2012 holiday rush ended. There was a slight difficulty: We require an unusual mix of office and warehouse space. Large machines, dock access, and concrete floors are normally found in huge warehouses. We needed all of this, plus professional office space in a relatively small space.

In March, we were pleased to find a 2500 sq.ft. office just days away from undergoing a construction makeover. We signed a lease and moved into our fully customized facility on June 1st.

New Assembly & Shipping Benches
New Assembly & Shipping Benches

Frequently accessed inventory is now footsteps away from our two main soldering benches. Nick also spent a laborious weekend assembling a massive table for assembly and a 7ft tall shipping station.

Not pictured: About 60% of this room is unused for now. Room to grow!

Laser Engraving Station
Laser Engraving Station

Soldering and laser engraving stations are equipped with 4″ industrial fume exhaust lines.

A Soldering Bench
A Soldering Bench
Front Office
Front Office
New CNC Room
Dock and CNC Machining Area

Building a Machine Shop

Last year we bought a Tormach PCNC 770 as our first foray into the world of machining. Within 12 months, we’d machined over 5000 parts on the Tormach. Notice it’s absent from the picture above.

As much as we valued the ability to machine our own parts, the PCNC 770 turned into the weakest link of our production process. We frequently found ourselves waiting for parts to be machined. It struggled to keep up with our busiest weeks, so Nick was forced to work 12+ hour days in December and January.

Plus, moving a CNC (even the entry level Tormach 770) is no trivial matter. Industrial movers quoted 10% of the cost of the Tormach just to relocate it from our old office to our new facility. I didn’t want to invest more in a machine that was holding us back.

Nick found a lightly used 2012 Haas Mini Mill 2 the week before our move. At 7.5x the horsepower and 4x the speed of a Tormach, we placed the PCNC770 for sale and upgraded to a Mini Mill 2.

Our new CNC (Haas Mini Mill 2)
Our new Haas Mini Mill 2, CNC

The Tormach was capable of producing about 45 Objective2 front plates per day. We’re now able to machine 135 of these parts in the same amount of time (3x faster).

To give you an idea of how quickly the Mini Mill 2 moves, here’s the first 30 seconds of machining a batch of endplates

And here’s the entire, 3-step process compressed into less than 3 minutes:

Fixing Objective2’s Power Jack

** We’re moving to a new office on Friday, May 31st. Orders placed after 10am CST tomorrow (5/31) will ship Monday! **

If you’ve assembled NwAvGuy’s Objective2 in the past year, you must have noticed that its power jack is discontinued. Alternatives to Kobiconn 163-7620-E do not fit.

One of many alternative 2.1x5.5mm DC jacks -- Does not fit!Substitute power jack for O2. Does not fit.

NwAvGuy last reached out to us on July 1, 2012 before mysteriously disappearing. Two months earlier, he’d discussed revising the O2 PCB. The discussion is archived for those interested: NwAvGuy Emails

From:Northwest AvGuy
Sent: Tuesday, May 01, 2012 12:30 PM
To: John Seaber
Subject: John: O2 Power Jack

Have you found an alternate power jack for the O2, are you modifying jacks to fit, or do have enough of the old ones for now? I’m getting more questions about the discontinued jack and trying to decide what the best solution is.

If I revise the PCB artwork I would fix the jack footprint and move the via under the corner of the gain switch. Are you aware of any other necessary board revisions?

On Tue, May 1, 2012 at 11:57 AM, JDS Labs Inc. wrote:

We source unique parts in large quantities, so we have enough power jacks to last all year.

Kobiconn 163-179PH-EX is close. Dimensions aren’t a perfect match to 163-7620-E, but it should fit existing O2 boards and front plates [Edit: 163-179PH does not fit]. Breaking mechanical compatibility with the original board/plates would be a mess.

No other revisions should be necessary!

On Tue, May 1, 2012 at 2:08 PM, Northwest AvGuy wrote:

Thanks for the reply. Yeah, I have a sample of the 179PH already and, as I posted on the O2 Summary comments, two of the tabs are a bit too big. A revised board shouldn’t change form, fit, or function of the assembled board.

Just beware before ordering a large number of PCBs the artwork may be revised so you might want to check in with me first.

We believed NwAvGuy would eventually update O2. Now that almost a year has elapsed, we can only hope he’s doing okay.

We’ve spent the past few months seeking substitute power jacks. No success. Jack manufacturer Kycon quoted a custom part, with tooling and minimum order quantity totaling $25k-$100k. Not worth it! The last thing we want to do is violate NwAvGuy’s work by disregarding the O2’s no-derivatives license. We’ll gladly respect any wishes he may have if he’s able to return in the future. Until that time comes, we’ve decided it’s time to proceed with NwAvGuy’s intention of sustaining O2 as a viable DIY project. That means the O2 PCB must accept common power jacks.

NwAvGuy only supplied Gerbers for the O2, which makes the design nearly impossible to modify without re-drawing the schematic and PCB from scratch (definitely unacceptable).

O2 v1.1a PCB Gerbers
Original O2 v1.1a PCB Gerbers

Zooming in on the power jack (J1), you can see that plenty of copper surrounds its 2.3mm holes:

O2_original_zoom
Original O2 v1.1a PCB Close-up

Most power jacks have pin widths of 3.0mm, instead of the small 2.3mm pins used by 163-7620-E. So, we only need to increase hole diameter at J1 by 0.7mm.

NwAvGuy left us with wonderful documentation. You can find this table in the O2 readme, and tool “T8” looks like the drill bit relevant to jack J1:

Tool Hole Size Hole Type Hole Count Plated
T1 28mil (0.7112mm) Round 104
T2 32mil (0.8128mm) Round 44
T3 42mil (1.0668mm) Round 23
T4 53mil (1.3462mm) Round 24
T5 55mil (1.397mm) Round 8
T6 62mil (1.5748mm) Round 12
T7 68mil (1.7272mm) Round 12
T8 91mil (2.3114mm) Round 3
T9 125mil (3.175mm) Round 3
Totals 233

To test this idea, I searched the drill file for “T8”. The first instance occurs at line 13, where this table is defined explicitly in Gcode:

M48
;Layer_Color=9474304
;FILE_FORMAT=2:4
INCH,LZ
;TYPE=PLATED
T1F00S00C0.0280
T2F00S00C0.0320
T3F00S00C0.0420
T4F00S00C0.0530
T5F00S00C0.0550
T6F00S00C0.0620
T7F00S00C0.0700
T8F00S00C0.0910
T9F00S00C0.1250
%

Tool names gain a prefix of ‘0’ throughout the rest of the drill file, and T08 appears with three coordinates on lines 250-253:

T08
X017Y-005452
Y-00305
X015189Y-00431

To confirm that T8 is the appropriate drill bit for the DC jack, I set T8 to an arbitrarily large size on line 13 and checked the visible result:

Changed drill size in NC Drill file to use arbitrarily large holes
Arbitrarily large T8 drill size confirms T8 is only related to O2’s DC jack

This test proved that T8 only affects holes at the DC jack. Thus, I changed T8 in the drill file to our desired hole diameter of 120mils (3.05mm). Here’s the visible result, showing successful 3mm, plated holes at the power jack:

O2 v1.1b PCB: Equal to NwAvGuy's v1.1a, with J1 holes enlarged from 2.31mm to 3.05mm
New O2 v1.1b PCB: Equal to NwAvGuy’s v1.1a, with J1 hole sizes increased from 2.31mm to 3.05mm

O2 v1.1b PCB fabricated and confirmed perfect!

Fits
CUI PJ-002A power jack (3.0mm pins): Fits new v1.1b PCB
O2 v1.1a in Green, O2 v1.1b in Purple.
Original O2 v1.1a in Green, Modified O2 v1.1b in Purple.

AVAILABILITY

Modified O2 PCBs are Now in Stock. You may also download the v1.1b Gerbers for your own use.

SUMMARY

O2 v1.1b is a straightforward manufacturing alteration to the O2 v1.1a circuit board. Specifically, holes of the power jack, J1, have been enlarged to accommodate standard power jacks. All aspects of the Objective2 remain unchanged from NwAvGuy’s work. The PCB layout is identical. Performance is identical. Even the silkscreen still shows “v1.1a” (admittedly confusing). The O2 v1.1b PCB merely allows builders to assemble O2 without encountering frustration from the DC jack.

 

How to Finish Aluminum

Disclaimer: This article has no audio related content. We hope the following manufacturing information will be useful to others.

A couple years ago, we naively expected that aluminum manufactures would perfectly interpret our engineering drawings and produce beautiful, black parts. After rejecting 4500+ aluminum cases in these past two years, I can tell you with certainty that this guy gives a false impression. There’s much more to fabricating a nice aluminum product than simple anodizing. Photos below are a chronicle of our progress.

Raw Aluminum

Our raw cases arrive from the aluminum manufacturer looking something like this:

Raw Aluminum
Raw aluminum extrusion for C5, “mil” finish (i.e., no finishing)
Scratch on right -- oops!
Right-most part was scratched prior to anodizing

Rough, huh? Sometimes we see deeper scratches and dents, and parts can even arrive covered in grease and oil.

Anodizing fixes none of this! Any scratches or defects visible before anodizing will remain visible after anodizing.

Brushed + Anodized Aluminum

We added brushed finishing to c421 after realizing that we couldn’t expect aluminum manufacturers to deliver parts in perfect condition:

Similar case w/brushed texture and black anodizing

Brushing solved the immediately visible problem in our first manufacturing attempts, but created new issues. The texture of production parts was rougher than samples. And here’s what happens with a heavy brush intensity:

Brushing can remove too much material, altering the case profile
Heavily Brushed piece at Left, Original piece at Right.

Pros:

  • Relatively fast to perform
  • Generally low cost
  • Brushed appearance is popular

Cons:

  • Since brushing a part is essentially like rubbing sandpaper against its surface, brushing can alter part tolerances (see above image).
  • An aggressive brushed finish can create a rough, undesirable texture.

Bead Blasting

When we began designing C5, we knew that enclosure quality needed to match the awesome new circuit board. Brushed cases had to go. Our local anodizer suggested a very fine bead blast (aka, “peening”).

Bead blasting is essentially like a pressure washer that uses “abrasive media” instead of water. Any media can be used: walnut shells, sand, and glass beads are common. Pick a media, a pressure, a distance from the part, and then blast the surface. Most shops say it’s an art.

Ultra fine glass beads produce a soft appearance similar to Apple’s Macbook:

Same part with bead blasting
Bead blasted extrusion (C5 case)

Bead blasting dulls the part finish. While appearance is excellent before and after anodizing, surface texture oddly changes after anodizing. In some cases, the texture is comparable to a chalkboard.

We also noticed that black parts turned out especially dull, unlike other colors.

Same bead blasted parts in Red and Black anodizing
Same bead blasted parts in Red and Black anodizing

Pros:

  • With the right bead blasting media and pressure, a bead blasted part looks excellent
  • Part tolerances are not altered

Cons:

  • Requires significant sampling/experimentation from your metal finishing shop
  • Cost is 50-100% higher than brushing
  • Most shops manually blast parts, which can lead to surface inconsistencies
  • Especially rough parts must be tumbled prior to blasting (even higher cost)
  • Anodizing yields a matte appearance, especially unsuitable for black

Bead Blasting + Bright Dipping + Anodizing

Aluminum parts are normally caustic etched immediately prior to anodizing. If you substitute etching for a process called Bright Dipping, dullness is magically replaced by a brilliant appearance and pleasant texture.

Bead blasted parts at top; bead blasted + bright dipped parts at bottom
Bead blasted parts at top; bead blasted + bright dipped parts at bottom

The bright dipped parts shown above are not actually brighter. At another angle, you can see instead that light reflects more brilliantly at all angles. Notice the bright dipped pieces appear darker in this photo:

Bead blasted pieces at Top; bead blasted and bright dipped pieces at Bottom
Bead blasted pieces at Top; bead blasted and bright dipped pieces at Bottom

Pros:

  • Excellent surface appearance
  • Excellent surface texture
  • Cost is comparable to standard anodizing

Cons:

  • Bright dipping is extremely corrosive, so it’s rarely offered in the United States
  • Carries all other downsides of regular bead blasting (see above)

Hopefully this helps someone in their manufacturing adventures. Special thanks to Tom at Archway Anodize for making our experiments possible!

Best DAC?

ObjectiveDAC
ObjectiveDAC

Lately we’ve received several phone calls which start like this:

Customer: “Hi, I’m new to high end audio. Does [insert product] have a DAC in it? Do I need a DAC?”

From these discussions, two observations are clear.

  1. DACs are suddenly “hot” on the market.
  2. The majority of prospective DAC buyers, especially those new to the scene, have almost no idea what a DAC does.

We sell one of the best reference grade DACs in the world, so this is concerning to me. I’d never shell out $100+ to buy something I didn’t fully understand, and the average customer is no different. He’s turning to Google to gain a better understanding of these mystical “Digital-to-Analog Converters”. Unfortunately, the same people who call keep telling me that they can only find bad/mixed information.

What is a DAC?

Put simply, a DAC is the chip which turns your digital music into something you can physically hear. Every digital audio player (laptop, cell phone, tablet, iPod, etc.) already has an internal DAC and a weak headphone amp.

In terms of the audio chain: [Digital audio source] –> [DAC] –> [Amp] –> Headphones

Why use an external DAC?

If you’re shopping for a DAC, your goal is either to fix poor audio performance, or you’re in the much greater pursuit of reference quality audio. Either way, you’re seeking peace of mind that your audio is audibly perfect.

NwAvGuy wrote the best guide I’ve read to date: Headphone Amps and DACs Explained. If you read nothing else in his article, consider these excerpts:

iPOD DACs: I think most of these are a waste of money as most modern iPods already have very respectable DACs in them. For example, the iPod Touch 3G’s DAC outperforms the one in the popular NuForce uDAC-2.

PC DACS: […] a lot of PC’s have respectable DACs in them. If the problem is your headphones not getting loud enough, just an amp may be enough.

My advice to new users mirrors NwAvGuy’s recommendations. If you want better audio, start with nicer headphones and a headphone amp. An external DAC is a great investment when your source is noticeably poor (background hiss, device interference, etc.).

When you connect a headphone amplifier to an audio player, the amp relieves your audio source from its difficult job of driving headphones. The source now sees an easy load from the external amp. Assuming you’ve selected a high quality headphone amplifier, output power improves, output impedance issues are resolved, THD+N improves (due to the easier load), and background hiss is minimized through input attenuation at the amp. In other words, a headphone amplifier solves the most audible problems.

A high performance DAC ensures that your headphone amp receives a high quality input signal. Since signal quality of most DACs is already excellent, further improvements from an external DAC tend to be minimal.

Best DAC?

Lifehacker polled users last month for the Best DAC. The ODAC was nominated, and a tube based amp+DAC won the poll. Considering the $1000 pricetag of the winning nomination, lifehacker correctly identified that they’d actually created a poll of aesthetics. Results are more correctly titled, Most Popular Digital-to-Analog Converter. So, what is the best DAC??

Over the years, I’ve grouped users into three categories:

  1. Subjective audiophiles. Users who mainly ignore specifications and instead base their opinions on their own listening impressions, and/or impressions of other audiophiles.
  2. Objective audiophiles. Users who primarily consider benchmark performance when evaluating an audio device.
  3. Common users. New audio enthusiasts and everyone else, including non-audiophiles. These people aren’t sure what to expect from high end audio.

Jitter and DAC resolution these days are so excellent that the majority of common users and audiophiles we’ve talked to admit that they struggle to differentiate between one DAC and another. Unless your audio source delivers low quality to begin with, this is expected: You shouldn’t hear a reference grade DAC. That’s the point!

Therefore, there’s no such thing as the Best DAC on the market. Most modern DACs are equally capable of providing excellent audio. If you’re after higher quality sound, start with nice headphones and a headphone amp. If you’re after audio perfection, consider a reference quality DAC as well.

C5 Headphone Amplifier

Today we’re excited to announce our new C5 Headphone Amplifier:

C5 Headphone Amplifiers in Red, Slate and Silver
C5 Headphone Amplifiers in Red, Slate and Silver

C5 Production Status

  • Design: 100% complete
  • Engineering Samples: Approved
  • Benchmarks: 100% Complete
  • PCB Assembly: 100% Complete, on a UPS truck
  • Enclosures: In stock, awaiting anodizing February 19-22

Barring unforeseen catastrophic failures, C5 preorders will ship no later than February 28. Review samples and distributor orders will ship on February 22.

Wed., March 13 Update: The C5 preorder sold out this morning. Mass production began two weeks ago, so C5 will be in stock in just 2-4 weeks.

View All Status Updates

Tues., March 12 Update: 99% of preorders have shipped! New Slate C5’s ship immediately. New Red C5’s will ship next Tuesday, March 19.

Mon., March 11 Update: Slate anodizing remains on schedule for completion tomorrow morning. Our anodizer says this batch is turning out as desired.

Fri., March 8 Update: Over 75% of preorders have shipped (all Red and Silver). All Slate preorders are scheduled to ship by Tuesday evening.

Thurs., March 7 Update: We inspected and approved a new batch of enclosures today, and now expect to complete preorder shipments within 3 business days.

Tues., March 5 Update: We have encountered an “unforeseen catastrophic failure” as I wrote on February 16th. The enclosure delay mentioned last week was caused by our local metal finishing shop. Their job is to apply the smooth, blasted finish to C5 (bead blasting). As of last Tuesday, they realized they’d blasted our C5 cases with the wrong parameters. Already one week late, they called on 2/26 and promised to start over and deliver perfect pieces by Thursday, 2/28. All seemed fine, until we anodized those pieces. Our anodizer called this morning apologetically. His shop follows this blog and is well aware of the significance and beauty of C5. Every single piece from the “fixed” batch was not fixed. Anodizing had revealed severe cosmetic defects–all pieces from 2/28 were junk.

I drove to the blasting facility this afternoon and handed them two C5 enclosures: one from the first batch, and one from the 2/28 batch. The production manager was as shocked as we are, and will begin another batch in the morning with strict supervision.

It’s an absolute shame that one shop foiled our ambitions to ship early. As soon as we realized the possibility of failure, we began identical blasting production at a second metal finishing shop, for redundancy.

The Good News:

  • We have a strong supply of raw enclosures; without delays, metal finishing normally takes just 2-5 business days.
  • Over 61.5% of C5 preorders have already shipped

For those affected by the delay (mainly Silver and Slate preorders), we promise to upgrade all USPS First Class shipments to USPS Priority. Please do not hesitate to contact us if we can be more helpful!

Mon., March 4 Update: All Red C5’s have shipped. All outstanding preorders will ship by Wednesday.

Thurs., Feb 28 Update: Enclosure anodizing is in progress, and we still expect to ship on Monday afternoon.

Wed., Feb 27 Update: A large batch of C5 enclosures will enter anodizing by 1PM Thursday (a 1-2 day process). Preorders will resume shipping on Monday afternoon.

Tues., Feb 26 Update: Over 25% of C5 preorders have shipped. All PCBs have been tested and are awaiting final enclosure assembly. Our enclosure finishing contractors called this morning to report a 2-3 day delay, so remaining C5 orders will ship Feb 28 thru March 6.

Design Priorities

C5 is not a response to the Objective2, nor to competitors’ products. C5 began as a fun project in 2012 to build a smarter headphone amplifier to solve the single greatest hindrance we see in DIY audio: the analog volume potentiometer.

C5 is built for portable users who need a small amp with USB recharging, exceptionally low noise, sufficient output power, long battery life, and most importantly, a super fine volume control to handle sensitive headphones and IEM’s.

Analog Potentiometers’ True Performance

I interviewed an electrical engineer in January. He’d applied here after discovering the Objective2, and during our discussion, he asked, “What’s there left to design? The O2 is audibly perfect. How can you build anything better than that?”

Easy, there’s no such thing as a perfect product. Every design has its unique goals and constraints.

Our Chinese competitor says the Alps RK097 analog pots are “still the best” solution, presumably based on low cost and decent benchmark performance. NwAvGuy dismissed digital potentiometers as too expensive to implement with good performance, while acknowledging the major shortfall of the Alps pot he settled on for the Objective2:

 THE CHANNEL BALANCE PROBLEM: Devices with conventional volume controls may have audible channel imbalance at very low volumes [i.e., one side is much louder than the other –JDS]. It’s extremely difficult to manufacture volume control potentiometers that maintain tight channel balance below about -40 dB (referenced to full volume). — NwAvGuy

In this article he briefly describes how imbalance can be resolved with proper excess gain. The excess gain problem is primarily why we’ve custom built cMoyBBs for over five years. That is, setting a suitable gain usually avoids channel imbalance. Usually–until you’re sitting in a quiet room and want to listen at low volumes, or until you try a set of high efficiency headphones. Even at 1.0x gain, you’ll encounter major channel imbalance from your so-called high performance analog headphone amplifier in such situations.

Let’s take a look at channel balance of c421, measured by the dScope as I slowly turn the knob from maximum to minimum position:

c421: Severe channel imbalance
c421 Channel Balance (Alps RK10J, 3B Taper)

The yellow line represents the left channel; pink represents the right channel. Lines resting exactly on top of each other indicate audibly perfect balance (no deviation in L and R volume).

c421’s Alps RK10J imbalance grows after just -12dB. The problem becomes severe by -22dB, and it’s quite useless by -30dB. If you called or emailed in the past year, you know we didn’t recommended c421 for IEM’s. If you tried c421 without seeking our advice, you either listen above the imbalanced region, or you returned the product.

Here’s an Alps RK097 implemented in the cMoyBB (Objective2 uses the same series potentiometer):

cMoyBB / O2 Channel Imbalance (Alps RK097, 3B Taper)
cMoyBB / O2 Channel Balance (Alps RK097, 3B Taper)

Channel balance of the RK097 fairs much better, due to its larger mechanical size. You can see 1-2dB deviations at -25dB, with otherwise decent balance down to -40 to -50dB. And that’s where things get nasty. I only managed to turn the knob at a single point when the dScope cycled to measure the imbalanced region, which is exactly the problem IEM users face. You can either turn the knob to mute, or to a point of imbalance, or to a level louder than you’d prefer.

Even with the RK097, we still receive a few emails and phone calls each month about channel imbalance. So what good is a HiFi amplifier when it actually hurts your listening experience?

Going Digital

For years, audiophiles feared digital volume controls. Software based digital volume control is the worst, causing you to “lose bits”–the audio signal itself is digitally divided and becomes less precise. Bad!

Early digital potentiometers solved the basic mechanical problems of analog potentiometers. A digital potentiometer is electrically equivalent to an analog potentiometer. Both feature High, Low, and Wiper terminals. The potentiometer is mechanically or digitally set to determine the ratio of High:Low resistance. However, bad digital pots added a large amount of capacitance to the Wiper, and thus, audiophiles frowned at the resulting THD+N (often 0.1% or worse).

It’s 2013, and it’s finally time to say goodbye to the analog potentiometer. C5 features 64 steps of audibly perfect digital attenuation:

C5 Channel Balance: Atmega168A + DS1882
C5 Channel Balance (DS1882 + Atmega168A)

C5 presents only +/-0.1dB of deviation all the way down to -50dB, and only +/-0.55dB at -60dB! [Yes, you can only see 28 steps here, as I’m manually racing the dScope test duration by making larger volume transitions.]

In other words, C5’s digital attenuation achieves perfect audible balance at volumes -20dB lower than the analog Alps RK097. Remember that audio sounds twice as loud every 10dB, so this is no small improvement.

Reference Level Performance

C5 began as an experiment, and even I was skeptical that we could outmatch c421’s THD+N with a digital potentiometer. Thus, we bought a dScope III and set no project deadline and no budget. We’d either continue shipping c421’s, or continue experimenting.

C5 PCB
C5 Printed Circuit Board

By January 2013, it was clear that C5 was electrically complete. We quietly put C5 PCB’s into production instead of another batch of c421’s. C5 had not only hit our THD+N goal, it had matched the O2!

Specification C5 Measurement
Frequency Response  +/- 0.02 dB
THD+N (20-20kHz, 150 Ω) 0.0009%
THD+N (20-20kHz, 32 Ω) 0.0045%
Noise -105 dBu
Crosstalk @ 150 Ω -67 dB
Inter-channel Phase @ 1kHz +/- 0.01°
Channel Balance +/- 0.55 dB, all volume positions
Max Output @ 600Ω 4.146 VRMS
Max Output @ 150Ω 3.337 VRMS
Max Output @ 32Ω 1.010 VRMS
Power Supply 14.0 Vpp
Output Impedance 2.2 Ω
Battery Run Time 11-14 Hours
Charge Time 2 Hrs to 80%, < 4 Hrs to 100%
Operating Temp –40°C to 85°C
Operating Humidity 0 to 85% Rel. Humidity
Dimensions (excluding switches) 99.5 x 61.5 x 14.0 mm (LxWxH)
Weight 4.2 ounces
C5 THD+N Measurement @ 150 ohm load
C5 THD+N Measurement @ 150 ohm load: 0.0009%
C5 Idle Noise
C5 Idle Noise
C5 Frequency Response (Flat)
C5 Frequency Response (Flat): +/- 0.02 dB
C5 Frequency Response (Bass boost)
C5 Frequency Response (Bass boost): +6.5dB @ 80Hz

Achieving high output power was not a primary goal of C5. Referring to its design objectives, portable users do not need inordinate amounts of power (note: P = V^2/R); you need run-time and just enough power. C5 has equal output power to that of c421, and we know from measurements and subjective results that c421 and C5 are well suited to driving 90+ dB/mW headphones. IEMs and common 32-250 ohm dynamic sets are okay for C5. It’s not meant for your planar orthodynamics. Therefore, instead of setting unnecessary supply voltage and output power, we set adequate supply voltage for moderately demanding headphones and achieved run-time of 14 hours.

Dual LDO Supply Regulation

C5 builds upon c421’s proven power stage by adding cutting edge TPS7A4700 and TPS7A3301 regulators to the supply rails. Hats off to HiFiDuino’s blog post for catching my attention back in September.

We wanted to place LDO’s in c421, but there was no way to control them, and without control, unsynchronized LDO’s produce unsafe turn-on transients. C5 is smarter than c421, so its firmware simultaneously enables the positive and negative LDO’s after the rest of the amp has initialized. You hear only a safe turn-on transient with C5, and reap the benefits of ultra-low supply noise.

Features

  • Digital Stepped Attenuation (63 steps + mute)
  • Dual Gain: 2.3x or 6.5x, MOSFET controlled
  • Bass Boost: +6.5dB @ 80Hz
  • 20-Minute Low Battery Indication
  • 0.1% Thin Film Resistors
  • 1200mAh, 3.7V Li-Ion Battery
  • Smart USB Charging
  • Ultra Low Noise +/-7V rails
  • 3.5mm Input and Output Jacks
  • Gold Immersion, 4-Layer Printed Circuit Board
  • Atmega168A MCU w/Opensource Arduino Firmware
Feature How to Use
Volume Hold volume lever left to decrease volume, or right to increase volume.
Gain Push volume control to toggle high/low
Bass Boost Toggle up for normal audio, toggle down for bass boost

A single LED conveys all of C5’s behaviors:

Amplifier State LED Status
Off Off
On Solid Green
Low Battery Flashing Green
Charging Blue

 

Opensource Firmware

C5 Proof of Concept
C5 Proof of Concept

The C5 proof of concept began as an Arduino Pro with messy wires coupled to a c421: DIY style.

Writing firmware for a digital potentiometer is surely a hurdle for many in the DIY audio community. In pursuit of retiring analog potentiometers in DIY HiFi, we’re releasing C5’s firmware under the CC BY-SA 3.0 license. Note that a 6-pin header and ISP programmer are required to write to C5. Enjoy!

Happy 2013!

Happy New Year, everyone! 2012 was by far our best year ever, at 430% revenue growth over last year. Incredible!

No surprise to us, “Erik” at Headfonia.com named the O2+ODAC combo his personal Product of the Year:

“I have heard and seen more gear in 2012 than in all the years before combined. For me, the rise, and subsequent disappearance, of NwAvGuy has probably been the most prolific event this year. Like it or not, the release of his maximum-value Objective2/ODAC combo (designed in 2011 but properly distributed in 2012) really shook up the scene and therefore deserves it’s place as my personal Product of the Year 2012…”

Well put. While we can’t claim absolute responsibility here, we ramped up production of the Objective2 and O2+ODAC combos in 2012 and the effect has been nothing short of amazing. NwAvGuy completely changed our business plans for the year, as well as my perspective on product development and customer recommendations. As the Objective2 gained popularity, we gained even greater respect for NwAvGuy’s contributions to the DIY scene, especially in the way of subjective bias.

Objective2, Black Edition
Objective2, Black Edition

A little surprise: Yes, we have black O2’s and O2+ODAC combos in stock. These have been available for a while now upon special request. We’ll add greater store visibility for the Black Edition O2 as soon as our knob supplier catches up.

Inventory Day

The end of the year is peak season for us, and that means two things. First, our production team is as busy as Santa’s elves. Second, we’re preparing for tax season. Part of this preparation is an annual Inventory count, in which we count everything in the office: chairs, computers, soldering irons, circuit boards, resistors, capacitors, IC’s, etc…

On the flip side of this enormously busy month, it’s equally important for us to reinvest spare cash in new equipment. We’d already acquired a CNC and laser engraver back in the summer. So in the name of NwAvGuy, we made one final acquisition in December–a PrismSound dScope Series III audio analyzer.

Our new dScope Series III Audio Analyzer
Our new dScope Series III Audio Analyzer

The dScope III is an amazingly powerful tool, which enables us to continue developing great products, with or without NwAvGuy.

We may find other uses for the dScope, aside from R&D. Rockford Fosgate ships unique test performance sheets with some of their car audio amps. Maybe some of you guys would like to see actual printouts of your new amplifier’s output? Tell us!

Thanks to everyone for another terrific year!

Cyber Monday at JDS Labs!

Today is Cyber Monday, so we’re excited to offer free shipping! Terms are simple:

  • Free shipping applies to all orders weighing 3+ ounces, which includes all of our DACs and headphones amplifiers
  • Orders placed with free shipping will be mailed via USPS First Class or USPS First Class International. If your order is too heavy for First Class mail, we will upgrade your shipment to the next fastest shipping method.
  • Shipping insurance remains mandatory for international orders over $75 USD
  • This offer applies only to orders placed on Cyber Monday, November 26, 2012 from 12:00AM to 11:59PM Central Standard Time (UTC-6). No exceptions.

 

Digital Audio vs. DPC Latency

Quick note: Our office will be closed this Thursday and Friday while we spend time with our families for the Thanksgiving holiday. Orders placed Nov 22-23 will ship on Cyber Monday.

We need to thank Steve Guttenberg for his fantastic review last month. Site traffic spiked that week, crippling my blogging time as I pitched in to help with production. That overtime taught me a painful lesson in October–don’t touch aluminum splinters!

DPC Latency

Saving you from the long string of events which led to this discovery, this story is brought to you in part by a buggy new office PC and hours of Googling…

If you’ve spent any considerable amount of time listening to music from your computer, you’ve probably heard glitches in the form of a pop or brief “looped” playback. Although increasingly rare, these problems are not extinct.

Pops and glitches don’t exemplify reference grade audio, and a hardcore audiophile doesn’t even listen to music from a computer. But that’s beside the point. Most of you do use your computer for music listening from time to time, and it would be nice to understand why these glitches occur.

Fortunately, Thesycon offers a tool to measure DPC Latency in real time. DPC Latency is essentially a number which can indicate how much time has elapsed since the soundcard (or DAC) last received a packet of audio data. If too much time goes by before the next audio packet is sent, the sound system has a digital heart attack. It skips a beat and loops whatever audio data was last received.

DPC Latency of a JDS Labs workstation
DPC Latency of a JDS Labs workstation

Thesycon says that DPC latency below 500µs is sufficient for “real-time streaming of audio and/or video without drop-outs”. Next time you hear audio stuttering, you can measure the effect as you experiment with solutions.

 

Going Black

Here’s a production lesson we learned over the summer: Black anodizing looks better than silver, and it’s easier to engrave.

Engraving plain aluminum (“silver”) parts requires a special type of spray paint, which costs $70 per can. The parts must be cleaned, sprayed, dried, and then engraved at a staggeringly slow speed on the laser engraver. Then we rinse off the spray paint to clean the parts. It’s slow.

Engraving black anodized aluminum is much friendlier. We place parts in the engraver and set speed to maximum. Finished.

c421 Black Edition

Anyway, Nick has done another fantastic job transitioning c421 case production to our in-house CNC!

The c421 Black Edition actually marks a small internal change. In response to In Ear Matters review in June, we swapped output ferrites from an 11 ohm part to a 2 ohm part (PCB has not changed). It’s an extremely subtle change which can be made to any c421. Black endplates are also available as an upgrade kit for current c421 owners.

Black ODACs

Similarly, our Standalone ODAC and RCA Standalone ODACs are also now built primarily in black.

ODA Update

If you know about NwAvGuy’s ODA project, you already know as much as we do (that is, not much). Judging by his blog, he’s taking an extended break. That’s all we know for now.

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