How do I order an assembled CH02?

Order assembled modules, a subpanel for each module, and the right version of the CH02. When the modules, subpanels, and chassis versions match, the cart calculates a discount.

For example, a 3124 killer would be
4x A12BKA $1196 Preamp modules
1x CH02KA-4$499 2U chassis - includes power supply, wiring, hardware, etc.
4x CH02-SP-A12 $15 Sub-panel for A12 - order one per module
Discount $229 Calculated automatically
Subtotal $1526 Total before shipping

Add blanks for a cleaner front panel look

4x A12BKA $1196 Preamp modules
1x CH02-CH $499 2U chassis kit - includes power supply, wiring, hardware, etc.
4x CH02-SP-A12 $15 Sub-panel for A12 - order one per module
4x CH02-SP-BNK $15 Blank sub-panels - order one per space
Discount $229 Calculated automatically
Subtotal $1586 Total before shipping
What do I need to order to build a complete preamp?

You'll need a chassis kit, at least one preamp module kit, and subpanels to match.

For example, for a two-channel N72 kit you'd order:

2x N72KF$658Preamp modules
1x CH02KF$4992U chassis kit - includes power supply, wiring, hardware, etc.
2x CH02-SP-N72$15Sub-panel for N72 - order one per module
Discount$189Calculated automatically
Subtotal$998Total before shipping

You can order assembled modules and install them yourself:

1x N72KF$479Preamp modules
1x N72KA$329Preamp modules
1x CH02KF$4992U chassis kit - includes power supply, wiring, hardware, etc.
2x CH02-SP-N72$15Sub-panel for N72 - order one per module
Discount$189Calculated automatically
Subtotal$1148Total before shipping
Do the kits include all parts?
Our kits are complete down to the last screw, but you'll need to supply tools and solder. Please see the Bill of Materials for each kit to see exactly what is included. Please see our assembly tips page for suggestions on tools and supplies.
What else do I need to buy?

If you don't own them already, you'll need a good soldering iron, digital multimeter (DMM), electronics solder, and a few hand tools. Please see the kit assembly instructions for a list of required tools and the assembly tips page for suggestions on tools and supplies.

Is there a discount for multiple modules?

No, but if you order a chassis and at least one module at the same time, the shopping cart calculates a substantial package discount.

For example, a complete kit with a single T15 would be

1x T15KF$99Preamp module
1x CH02KF$4992U chassis kit - includes power supply, wiring, hardware, etc.
1x CH02-SP-T15$15Sub-panel for T15 - order one per module
Discount$184Calculated automatically
Subtotal$429Total before shipping
Are there any discounts available?
The shopping cart calculates discounts for specific item combinations.
Complete CH02 Kit Discount:
  • CH02-CH Chassis
  • At least one preamp module, kit or assembled.
  • Front sub-panel to match the module.
Op-Amp Discounts
  • Each SC10KA or SC25KA ordered with an A12KF or A12KA.
For example, a complete CH02 kit with a single A12 and SC25 op-amp would be
1x A12KF-2S$249Preamp module
1x SC25KA$79Discrete op-amp
1x CH02-CH$4992U chassis kit - includes power supply, wiring, hardware, etc.
1x CH02-SP-A12$15Sub-panel for A12 - order one per module
Discount$213Calculated automatically
Subtotal$629.00Total before shipping

Please use the shopping cart to calculate the discount for your order.
Can I mix and match modules within a single CH02?
Yes, you can load up to eight (8) modules in any combination in a single CH02.
If I order all assembled modules, will I get an assembled preamp?

No, you will still need to install the modules, power switch, and LED assembly, connect the wiring harness, and button everything up. Please see the chassis assembly instructions for details. Note that there is no combination discount for orders that include a CH02KF without at least one preamp module kit.

For a pair of N72s fully assembled and installed, order
2x N72KA $958 Preamp modules
2x CH02-SP-N72 $15 Sub-panel for N72 - order one per module
1x CH02KA-2$499 2U chassis - includes power supply, wiring, hardware, etc.
Discount $189 Calculated automatically
Subtotal $1298 Total before shipping
Do I need to order an op-amp with each module?
No, only the A12 and J99 need op-amps that must be ordered separately. Note that the J99 needs two op-amps per module. Note also that the "B" versions of the A12 and J99 already include the op-amp circuitry. Please see the product pages for more details.
I only want to order a _____, not a whole kit. How much is that?
Sorry, we don't split kits or sell individual components.
How much does _____ cost?
Please use the shopping cart for price quotes. Simply add the items to the cart to calculate the combination discount, if any.
How much is shipping to _____ ?
Please use our shopping cart to calculate shipping rates. We ship large domestic orders via UPS only. Small domestic and all international orders also have USPS as an option. For more international shipping options, and possibly lower rates, consider using a forwarding service such as Shipito, MyUS, or Bongo.
Can I place an order over the phone?
We do not take phone orders at this time.
I don't like PayPal. How else can I pay?
We have had no problems with PayPal whatever, but we're happy to accept payment via money orders and personal checks. Money orders should be international and denominated in US dollars. Personal checks should be drawn on a US bank and will be held until funds have cleared into our account.
I don't like UPS. How else do you ship?
After trying all of the alternatives, we have settled on UPS as the best solution for our business despite the slightly higher cost. However, the shopping cart offers USPS priority mail as an option for small orders. If you are shipping to an FPO/APO address, please email sales@seventhcircleaudio.com for rates. For international orders, you may want to consider using a forwarding service such as Shipito, MyUS, or Bongo.
I'm ordering from outside the US. How much will customs duty, brokerage fees, and VAT cost?
As the importer, any customs duty and VAT is your responsibility. We do not assess or collect customs duty or VAT. Please contact your local customs office for rates.
UPS international shipping is very expensive. Is there an alternative?
The UPS international rates are actually competitive when equivalent levels of service are compared across carriers, but for many more international shipping options consider a forwarding service like Shipito, MyUS, or Bongo.
Import duties and VAT are very expensive. Can you declare my order as a gift?
Sorry, we have to declare the full purchase price for insurance purposes. Also because to do otherwise is illegal.
How fast do you ship? I need to use these on a session this weekend!
We generally ship in-stock items within 24 hours of receiving the order, but we can't guarantee it. If you're in a real hurry, building a kit probably isn't the best idea anyway.
Why build a preamp instead of buy one?
The best reason to build a preamp, or any other studio gear, is that you're interested in electronics and enjoy building things. It shouldn't be because you want to save money, though that can be a positive side-effect. The satisfaction of building a piece of gear that is the sonic equal of just about anything on the market should be your biggest motivator.
Is it safe? Will I burn my studio down?
As long as you take basic safety precautions all of our kits are completely safe. Like all other AC line-powered devices the CH02 power supply can present a shock hazard, but unlike some other kits our power supplies come fully assembled and tested. Unless you go poking around in the power supply while it's plugged in, you won't encounter any hazardous voltages while building our kits.
How much do I need to know about electronics?
You should be able to identify various components such as resistors, capacitors, diodes, transistors, etc. You should have heard of Ohm's Law and have some concept of the relationship between voltage, current, and resistance. You should be be able to use a digital multi-meter (DMM) to measure voltage and resistance. You don't need to understand the behavior of the circuits in detail, and if you follow the assembly instructions with reasonable care you won't need to know how to troubleshoot them, either.
Where can I hear one of your preamps?
In your own studio. Order assembled versions of the modules you're interested in and audition them in your own space, on your own material. Keep the modules you prefer and return the rest, or exchange the assembled modules for kits.
What's the best module for recording _____ ?
We are happy to provide measurements and specifications, but we prefer to leave the subjective judgments to you. Order assembled versions of the modules you're interested in and audition them in your own space, on your own material. Keep the modules you prefer and return the rest, or exchange the assembled modules for kits.
Do I need an adapter for 220V?
It depends. The CH02 power supply will accept any mains voltage from 85VAC to 250VAC. No jumpering or switch setting is required. The OneShot ships with a 115VAC "wall-wart." If your mains voltage is different, you'll need an adapter or a different source of 24VAC for the OneShot.
I want to mount your modules in a 1U enclosure. Can you recommend any?
Yes! Our new PC01 OneShot chassis holds a single module and includes a DI. You can mount up to four on a Raxxess universal shelf.
Why don't the kits have meters?
Meters are nice, but really not necessary at the mic preamp. Every one of our preamp modules has more headroom than professional A/D converters, so it's extremely unlikely the preamp will clip before you're in the red. That being said, look for an add-on meter module in the near future.
Are your modules compatible with my API lunchbox?
Definitely not. Our modules are not compatible with 500 series racks either mechanically or electrically.
Can I connect my preamp to an unbalanced input (like an FMR RNC)?
Absolutely. All of our modules provide fully floating and balanced output circuits that can be connected directly to unbalanced inputs. Cables should be wired as follows:

Balanced XLR Unbalanced TRS
Pin 1 (S)hield
Pin 2 (T)ip
Pin 3 (S)hield
What's an op-amp?
"Op-amp" is short for operational amplifier. The A12 and J99 modules need op-amps in order to pass a signal. IC op-amps are also used as DC servos in the A12, C84, J99, and T15 modules.
What does the op-amp do?
In the A12 and J99, the op-amps do the basic job of amplifying the audio signal. Without the op-amps, they won't pass a signal.
How much skill does it really take to build one of your kits?
Our kits are definitely not for beginners and you probably should not undertake one as your first foray into electronics. You should already know how to solder well, be willing to follow instructions, and pay close attention to details. The most important asset to have, however, is patience. Please see the resources page for some good beginner projects. Once you have a small effects pedal or similar project under you belt, you should have no trouble with a preamp.
How long does it take to assemble a complete kit?
Typical assembly times are as follows, though if you have limited experience or can't work in large blocks of time it might easily take two or three times as long.
A122.0 hours
C843.0 hours
J992.5 hours
N723.5 hours

Final assembly, that is, installing the completed modules in the chassis and connecting the wiring harness, will take about 10 minutes for each module plus another 30 minutes to an hour to get everything buttoned up and the knobs on. Figure 8 hours or so to construct a complete 2 channel N72 kit.
I'm pretty good at soldering cables. Will I have trouble with your kits?
Building and repairing cables is valuable soldering experience, but it doesn't necessarily help when it comes to PCB assembly. There's no better preparation than actually building a few projects on PCBs, or at least practicing soldering components to copper clad perfboard. Please see the resources page for some good beginner projects.
What soldering iron should I use?
We recommend the Hakko 936 because it's reasonably priced, heats quickly, is comfortable to use, and replacement tips are easy to find, but other temperature-controlled irons from Metcal, Weller, Pace, Tenma, etc. will work just fine. We highly recommend an iron with a grounded tip and static-dissipative handle.
Do I need a special tip for my iron?
The standard tip that comes with most irons tends to be a bit large for a lot of PCB work. We find that a small chisel tip (about 1mm) is better suited for out kits. Keep the standard tip for soldering connectors.
What temperature should I solder at?
We like to work fast at a high temperature, about 750 degrees F. If you need more than a few seconds to make a good joint, run your iron at a lower temperature.
Should I use lead-free solder?
We recommend 63/37 "no-clean" wire solder such as Kester 24-6337-8809. This solder contains lead and is the easiest for beginners to work with. 60/40 is also perfectly acceptable, but requires a bit more care so as to not make "cold" joints. 60/40 spends more time in an intermediate semi-liquid state compared to 63/37, so you must be sure to keep the joints immobile until the solder solidifies completely. We also recommend .025" or smaller diameter solder because it is much easier to control the amount applied to the joint. The most common error we see is joints with too much solder. We do not recommend lead-free solders unless you have considerable experience with electronics assembly.
Are the kits RoHS compliant?
With a few exceptions all the components in our kits are lead-free, but we're not yet certified as RoHS compliant.
Do I need an oscilloscope?
An oscilloscope is useful for setting the fine bias adjustment on the N72, but it is not required. However, a decent oscilloscope and signal generator should be part of every studio's toolkit. If you decide to invest in a scope, look for a dual-trace model with at least 20MHz bandwidth and the ability to operate in "X/Y" mode. Look for a signal generator that provides sine and square waves to at least 100KHz.
Don't I need an oscilloscope to get the best performance out of the N72?
Tweaking the bias allows the circuit to deliver maximum output before clipping, but the improvement in performance is very small and not audible in actual use. Realize that the input circuits of virtually all A/D converters and most tape machines will clip well below the N72's maximum output level, even when biased with just a voltmeter. If you're determined to tweak the bias but don't want to invest in an oscilloscope, you can use your DAW to visualize the waveform instead. However, you'll have to pad the output of the N72 sufficiently (20dB should be sufficient) to avoid clipping the input of your A/D converters.
What kind of support can I expect?
We offer free support via our message board and e-mail. Most common questions have been asked and answered on the message board, so it should be the first place to check when you have questions.
Is there someone I can call?
We welcome calls, but don't be surprised if there's no one available to talk to you right away. Support via e-mail is always available, however, and we prefer to answer your questions that way. We'll get back to you within 24 hours, usually much quicker.
My kit doesn't work. What do I do?
Keep calm. Don't start replacing parts at random. Carefully examine your work and make absolutely sure that every part is where it's supposed to be. Make absolutely sure that polarized parts are installed the right way round. Carefully re-flow all of the solder joints on the board. If that doesn't do it, describe your symptoms on our message board as clearly and completely as possible. Send the same description to support@seventhcircleaudio.com and we'll give you specific troubleshooting advice.
I've tried everything but still no luck. What next?
If you've carefully checked your work, posted your problems to the message board, e-mailed us for suggestions, and still can't get your assembled kit to work, please send it back for repair. Check the support page for details.
How long will it take for you to fix it?
We'll get to it ASAP, but don't be surprised if it takes as long as 6 weeks or more for us to get it back to you.