Frequently Asked Questions
How do I request custom engravings?
Custom engraving is free with most new products. You can specify text or an image by clicking ENGRAVE in the shopping cart. Best engraving images use:
- Color Depth: Black-and-white or grayscale
- Resolution: Vector, or minimum 600ppi (1 inch = 1*600 = 600 pixels)
Your image will be scaled for best fit onto the top center of the enclosure. See also: Custom Engraving Examples and More Custom Engravings. Please take the time to review both articles! You may use the Order Notes field during checkout to describe image placement and expected appearance.
Engraving usually takes a few minutes and has minimal impact on shipping time.
What is B-Stock? Can you share pictures?
B-Stock amplifiers and DACs contain brand new electronics. We classify enclosures as "B-Stock" when accidents occur in production. This usually means someone scratched or dropped a part, or it may exhibit small engraving or anodizing defect(s). Most cosmetic errors are difficult to notice. We prefer to set a high standard.
Please realize that B-Stock enclosures are offered at a loss, each enclosure is unique, and inventory is constantly moving. In other words, we cannot provide pictures or guarantee specific enclosures.
Accessories: We may supply new or open-box AC transformers or cables with B-Stock amplifiers and DACs.
Packaging: B-Stock Elements, EL Amps, and EL DACs are usually packaged in foam padding only (no retail box). Full retail packaging is rarely used for B-Stock in order to provide you with the best value. All amps and DACs are cleaned and disinfected upon successful completion of the hand testing process. By nature of minimal packaging, please anticipate the possibility of particulate matter.
All B-Stock Objective amps, DACs, and preamps are packaged in standard JDS Labs boxes.
Do you ship internationally?
Yes, JDS Labs ships worldwide. Please see our Shipping page.
Can you alter customs fees?
We utilize an automated shipping system which enters accurate item information on every package. Shipments outside of the United States may incur customs fees, duties, and/or taxes upon arrival. We have no advance knowledge of such fees, cannot manipulate the values, and cannot pay potential fees for you.
What payment methods do you accept?
You may checkout with any credit card, debit card, or PayPal account. Electronic bank transfers are supported through PayPal. Contact us if you require an alternative form of payment.
Where is my order?
We ship promptly—often within hours of receiving an order. Please check your e-mail (and junk mail folder!) for our automated shipment notification.
Please note that tracking information is not provided with First Class International or Priority Mail International shipments. Status information is only provided during package acceptance at the post office. There is no way for JDS Labs or the United States Postal Service (USPS) to track these orders. Delivery time of 2-4 weeks is typical for international packages.
Where are your products made?
All of our amplifiers and DACs are sourced and assembled in the USA! Our surface mount PCBs are assembled in California. We perform thru-hole soldering, final casing assembly, testing, and packaging in our own facility in Illinois.
A large portion of our facility is devoted to our machine shop, which allows us to perform 100% of aluminum CNC machining and engraving. Thus, we're able to competitively manufacture JDS Labs products in-house, here in the United States.
How do I connect an amplifier to a headset?
Headsets are headphones with a microphone attached. Most rely on a 4-pin TRRS connector, so you will need to split the headphone anmic signals using a TRRS-to-TRS splitter, then:
- Connect the splitter's headphone output to the headphone jack of your amplifier.
- Connect the splitter's mic output to your PC's existing mic port (usually pink).
- Connect a cable from your PC or DAC output to the input of your amplifier. PC outputs are usually green.
How do I connect a DAC to my phone or tablet?
You will first need to obtain an appropriate adapter.
- USB Type C Devices (Nexus 5X, 6P, Pixel, etc.) → Anker Type C Adapter or Monoprice Type C Adapter
- Micro USB Devices (Most Androids) → Micro USB Adapter
- Lightning Devices (Apple iPhone and iPad) → Lightning to USB 3 Adapter
Please see Troubleshooting for more help connecting to Android and iOS.
Objective 2 and ODAC
What Gain should I choose?
It's best to select gain based on your audio source's output voltage.
For Objective2+ODAC, your audio source is ODAC, a 2.1VRMS output device. Optimal gain for all headphones driven by Objective2+ODAC is 1.0/3.3x. Only select a different gain if you will bypass ODAC and operate the Objective2 from a stronger or weaker, external audio source.
To choose gain for Objective2, refer to your audio player's output strength:
- 1.0VRMS (iPod, iPhone, many Androids, typical laptops, etc.) → Choose gain of 2.5/6.5x
- 1.5VRMS (most iMacs) → Choose gain of 1.0/4.5x
- 2.0VRMS (OL DAC, most aftermarket DACs) → Choose gain of 1.0/3.5x
- 2.1VRMS (ODAC RevB) → Choose gain of 1.0/3.3x
- >2.1VRMS (professional audio equipment) → Choose gain of 1.0/2.5x
Use Objective2's lowest gain position for most listening. Only press the High gain button when your combination of music and equipment is unable to reach a suitable volume at low gain. Please see the JDS Labs article Volume is Power for a full understanding of the relationship between headphones, gain, and power.
Can Objective2 drive my headphones?
Objective2 was designed to drive virtually all dynamic headphones, IEMS, and efficient planar orthodynamic headphones on the market.
To achieve enjoyable listening, simply determine your headphones' power requirements* using a SPL Chart, then ensure the amplifier can exceed this level. You will need to know your headphone's published impedance (Ω) and sensitvity (dB/mW or dB/V) to use the SPL chart.
Objective2 can generate the following power into the example headphones listed below. You can estimate values for other headphones inbetween these measurements:
- Maximum Power into 33 Ω → 613 mW
- Maximum Power into 150 Ω → 355 mW
- Maximum Power into 600 Ω → 88 mW
*Note that headphone manufacturers occasionally publish a "maximum power" rating. Maximum power refers to the amount of energy the drivers can sustain before failing, and is often considerably higher than suggested listening power!
Can Objective2+ODAC be used with PS4?
Yes, simply connect Objective2+ODAC via USB, then navigate to:
Settings --> Devices --> Audio Devices --> Output Device --> USB Headphones(ODAC RevB)
PS4 is known to limit its USB Audio output volume. If you plan to listen to your DAC with a PS4, please tell us when placing your order. We can force your DAC's firmware to require PS4 to set 100% output volume. Alternatively, you can pair your Objective2 with OL DAC and rely on optical audio.
Are RCA jacks better than 3.5mm jacks?
Crosstalk performance of RCA jacks is 0-20dB superior to a 3.5mm jack (depending on frequency). However, this measurable advantage exceeds the capability of the human ear. Since most users are unable to audibly distinguish between a 3.5mm and RCA jack, these options should be considered audibly equivalent.
Therefore, we recommend that you choose jacks based on cabling convenience or personal preference.
Are 1/4" headphone jacks better than 3.5mm jacks?
Sound Quality: Sound quality is identical between 1/4" (6.35mm) and 1/8" (3.5mm) audio jacks.
Mechanical Life: The 3.5mm jacks used in Objective2 are rated for a lifespan of 5000 mating cycles, while 6.35mm jacks are rated for 10000 cycles. Thus, a larger jack has a longer mechanical lifespan. We've observed real world jack lifespans of 3-7 years for heavily used 3.5mm jacks. A 6.35mm jack should last even longer.
There is no loss of sound quality by using 1/4-to-1/8 or 1/8-to-1/4 adapters. However, adapters can increase the weight and/or length of the inserted cable. These additional forces can negatively impact the jack's mechanical life.
Summary: For maximum mechancial longevity, choose a headphone jack which matches the plug of your most commonly used headphones. There are no sound quality penalties. Treat your equipment with care and all jacks should last for years!
Can the cMoyBB be customized? How?
Yes, the cMoyBB can be custom built upon request to match your headphones. To request free customization, please mention your headphones in the "Shipping Instructions" field during checkout.
Customization is strongly recommended for low impedance headphones (32 ohms and below), such as Grados and most in-ear-monitors (IEM's/earbuds). We adjust over 10 components to optimize the amplifier's gain, bass boost, input attenuation, and ground circuitry to best match your specific equipment. There is no need to contact us in advance. We will automatically make all beneficial adjustments based on your order notes.
The cMoyBB is built by default to work well with any audio signal, including headphone output signals and line-level signals. If you plan to use a line-output adapter (LOD) cable, please mention this fact as well as your headphones during checkout. LODs produce a very strong signal which may require additional attenuation.
Please see our DIY modifications page for an explanation of all modifications.
The following cannot be customized:
- Opamp Chip
- Input Jack
- Output Jack
- DC Jack
- Bass Boost Toggle Switch
Different jack requirements (such as RCA or 1/4" stereo jacks) can be fulfilled using appropriate adapter cables.
What types of batteries can be used?
Rechargeable or non-rechargeable batteries (any) are safe to use in the standard cMoyBB. This includes alkaline, Li-Ion, NiMH, NiCd, etc.
You may use non-rechargeable batteries in the rechargeable cMoyBB v2.03R for listening, but never connect a power adapter to a cMoyBB v2.03R unless using NiMH 9V's!
Can the bass boost toggle switch be replaced with a knob?
This modification is only available to do-it-yourselfers, as described in the Assembly Guide. JDS Labs does not stock the required potentiometer for the modification.
What kind of cable do I need?
The cMoyBB uses standard 3.5mm (1/8") stereo input and output jacks. You will need a male-to-male 3.5mm interconnect cable (also known as a mini-to-mini cable) to connect your audio player to the amplifier.
Choose a heavily shielded cable. Look for terms such as "shielded," "noise-rejecting," or "braided." These cables use an additional grounding wire and and/or shielding sheath to avert a small amount of electromagnetic interference. Additionally, every cheap interconnect cable we have used has worn out in under a month, causing static, popping sounds, or a broken signal when the cable is wiggled. Invest in a rugged cable!
A line output adapter (LOD) is highly recommended if you audio player supports such a cable. These cables provide a stronger and cleaner signal than the headphone output jack. Look for 3.5mm interconnect and LOD cable recommendations in our store.
How long is battery run-time for the cMoyBB?
Battery life depends on volume, headphone impedance, amplifier customization, and of course battery type. A typical 9V alkaline battery in a standard cMoyBB lasts approximately 25-30 hours under heavy usage. Other battery types are also safe to use (NiCd, NiMH, Li-Ion, etc.). Run-time can be calculated as:Hours = (Battery Capacity, mAH)/(Current Drain, mA)
where Current Drain varies from 10-30mA. Battery Capacity of a name-brand 9V alkaline is about 500mAh; many NiMH 9V's have a capacity of 200-300mAh. The most inefficient configuration lasts 6.75 hours, while the best can last up to 50 hours.
The standard cMoyBB does not feature recharging capability. A NiMH battery and charger are worthwhile investments if the amplifier is to be used portably.
What is the benefit of higher voltage?
Voltage supplied to an operational amplifier sets the upper and lower signal boundaries for the opamp's output. When volume is increased beyond the maximum voltage boundaries, the opamp clips the signal and you will hear distortion. Therefore, higher voltage allows the opamp to produce higher volumes when driving high impedance headphones.
There is little benefit to increasing supply voltage for low impedance headphones (32 ohms and less). These headphones tend to demand more current rather than more voltage, so a 9V battery is adequate for most listening. Instead of extra voltage, the cMoyBB's maximum output current can be enhanced for low impedance headphones by adding a second virtual ground IC.
A summary of recommended cMoyBB configurations can be found under our DIY Assembly Guide.
All opamps are limited to "swinging" within a fixed distance from the voltage supply rails. Rail-to-rail opamps are able to drive signals much stronger before clipping. Thus, a rail-to-rail opamp is another way to achieve higher volumes, without resorting to higher voltage.
Why can't a cMoy be powered from a vehicle's +12V accessory supply?
The power adapter warning mentioned in the instructions sheet applies to every cMoy, not just the cMoyBB.
Most vehicular audio systems use an audio ground which is directly connected to the vehicle's negative battery terminal. Let's call this ground 'V-', and the vehicle's positive battery terminal 'V+'.
The negative DC power input of the cMoy is not connected to its audio ground. Instead, the cMoy's audio ground is electrically biased halfway between the battery/DC input voltage. Let's call the cMoy's positive and negative voltage supply connections 'Vp' and 'Vn', respectively. In other words, a cMoy power circuit creates its own 'virtual ground' equal to 0.5*Vp.
When you wire a vehicle's +12V supply to a cMoy, you are connecting the vehicle's V+ supply to the cMoy's Vp, and V- to Vn. This immediately presents no problems. Plug in a set of headphones and an iPod and your music will sound great. However, as soon as you plug the cMoy into your vehicle's auxiliary radio input, you are effectively shorting 'Vn' to the 'virtual ground'. This instantly fries the cMoy's power circuitry (the cMoyBB v2.02's optional 'D2' diode can sometimes prevent this damage).
Thus, if you wish to use a cMoy with a car/truck/motorcycle's auxiliary radio input, you must use a 9V battery to avoid shorting out the 'virtual ground.' The other option is to power the cMoy from the motorcycle’s battery and only use headphones and a battery powered external audio player, such as an iPod. Never use an audio source powered by the vehicle!
How do you change the operational amplifier chip?
Changing the opamp is simple: Remove the old chip, then insert the new chip in the same direction. Semi-circle notches can be found on the socket and chips to indicate proper orientation.
The chip sits in a socket from which it can be removed. If you do not own an IC extraction tool, use any thin, flat tool to pry the chip from its socket. A flathead screwdriver works well; needle nose pliers can also be used.
The above method applies to opamps in the standard DIP-8 package. To install a surface mount opamp, the chip must first be soldered to an appropriate SOIC-8 to DIP-8 adapter. The adapter can then be inserted into the amplifier as described above.
What other opamps do you recommend?
The stock OPA2227 opamp is an excellent chip. If you wish to experiment, several alternative chips are recommended in the Bill of Materials page. Because opinions vary from person to person, it is best for you to perform your own research and audition several chips. These discussions may help:
- Head-Fi — Best sounding opamp...
- Tangentsoft.com — Notes on Audio Op-Amps
- Blog.JDSLabs.com — SOIC Opamp Rolling and New Kits
The cMoyBB requires a dual operational amplifier chip in the DIP-8 package. Most dual-opamp chips (regardless of package style) will work in a cMoy. It is also important to choose an opamp with an acceptable minimum supply voltage. The cMoyBB supplies +/- 4.5V when running on a fresh battery. Therefore, an opamp with a minimum supply voltage of +/- 5V or more would be unacceptable when powered from a 9V battery. This limitation can be overcome by using a higher voltage power adapter.
It's also possible to use SOIC-8 (surface mount) opamps, or even pairs of single-opamps in conjunction with an appropriate BrownDog™ adapter. We sell such BrownDog™ adapters in our store for your convenience. Again, it's wise to research an opamp's compatibilty with the cMoy before dropping it into the circuit.
Finally, you may have noticed that we haven't recommended any specific chips. That's because audio is a subjective topic. What you enjoy hearing may differ the opinions of others. I personally enjoy the AD823, AD8620, AD825, OPA2604, and many other chips. Each opamp is unique and enjoyable in its own respect, so try as many as you can afford!