- General
- 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 PS03 can present a shock hazard, but unlike some other kits our power supplies come fully assembled and tested. Also, if you order the CH01KF and PS03KA at the same time the supply will arrive already installed in the chassis. Unless you go poking around in the 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?
Seventh Circle Audio products are only available directly from us, so there's no way to audition them in a store. However, several units are available from rental companies such as Cryptic Globe Recording in Nashville.
- What's the best module for recording _____ ?
We are happy to provide measurements and specifications, but we prefer to allow others to make such subjective judgements. Suffice it to say that each module excels in the same applications as their better known soundalikes.
- Do I need an adapter for 220V?
No. The PS03 will accept any mains voltage from 85VAC to 250VAC. No jumpering or switch setting is required.
- I want to mount your modules in a 1U enclosure. Can you recommend any?
We're not aware of any 1U chassis that will work without modification, but several come close. The chassis must provide the maximum 1U height throughout it's depth, not just have a 1U front panel, and be 8" deep. Be aware that we can't provide support for any problems you may encounter if you don't use our chassis and power supply.
- 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.
- 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 |
- Ordering
- What do I need to order for a complete preamp?
You'll need a CH01KF chassis, PS03KA power supply, WH01KA wire harness, and at least one module. If you order everything at the same time, the shopping cart calculates a package discount.
- How much does _____ cost?
Please use the shopping cart for price quotes. Simply enter the quantity of each item and click "add". The cart doesn't save any information and won't ask you for payment information until you click "Checkout".
- Can I place an order over the phone?
We do not take phone orders at this time.
- Are there price breaks for multiple modules?
No, but if you order a CH01KF chassis, PS03KA power supply, WH01KA wire harness, and at least one module at the same time, the shopping cart calculates a substantial package discount.
- I don't like PayPal. How else can I pay?
We have had no problems with PayPal whatever, but we're also 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.
- How much is shipping to _____ ?
For US addresses, please use our shopping cart to calculate UPS shipping rates to your ZIP code. For international addresses, please use the UPS web site to calculate shipping costs to your location.
- I don't like UPS. How else do you ship?
After considering all of the alternatives we have determined UPS to be the best available solution. The only exception is for FPO/APO addresses or others not served by UPS.
- UPS international shipping is very expensive. Is there an alternative?
The UPS international rates seem expensive but are actually quite competitive when equivalent levels of service are compared across carriers.
- I only want to order a _____, not a whole kit. How much is that?
Sorry, we don't split kits or sell individual components.
- Do I need to order a discrete op-amp with each kit?
No. The modules that require op-amps ship complete with IC op-amps. You don't need to order anything else to construct a working module. However, the A12 and J99 can accept discrete op-amp modules that offer increased performance. Please see their product pages for details.
- Can I order the PS03 as a kit?
No. Due to the complexity of the circuit and the high voltages present around the regulator, the PS03 is only available as an assembled and tested module. Note that if you order the PS03KA at the same time as a CH01KF, we'll install the supply in the chassis for you.
- 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.
- Assembly
- 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.
| A12 | 2.0 hours |
| C84 | 3.0 hours |
| J99 | 2.5 hours |
| N72 | 3.5 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.
- Support
- 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.
