Questions about CSA/UL certification of a commercial fully built amp.

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Besides protecting the end user it is also a good idea to insure yourself of liability. Many large insurance companies can steer you to the minimum testing you will need to be insured and indemnified from liability.
You can also do excessive load and fire safety tests yourself and photograph and document the entire process. You can then list the results identifying the minimum standards of abuse.
The medical field is the only area I have been directly involved in and can attest to the liability aspect of your endeavor. Cover your butt well. Today's society loves to sue anyone they deem has deep pockets.
One good thing in the U.S. anyway is the LLC statute which will protect you to the limits of your investment for today anyway.
If you make a quality product and are willing to stand next to with your reputation I do not think you will have to much trouble or expense going to market.
Do not forget to provide multiple input voltage selection in the initial design it will help with worldwide sales.
I wish you all the good luck in the world. Tad
Joined 2004
Paid Member
Your user manual should include a disclaimer that clearly states acceptable and unacceptable usage from a safety and product performance standpoint.

Conditions that may result in unsafe operation need to be disclosed, a statement about abnormal operation and what to do about it should be included as well. Examples of acceptable usage should include required ventilation, power, grounding, fusing, and all allowable as well as disallowed uses. (Indoors use only, non commercial use only, assure proper ventilation, do not use inappropriate loads as spelled out in the specifications, not designed for 24hr continuous operation, unattended operation, etc.)

Demonstrating that the product is properly designed and that potential hazards in use are spelled out along with a statement of remedies to the purchaser and limited liability on the part of the seller should be included.

You must make sure that the prospective buyer understands all of this prior to purchase, and you must make sure that no conceivable fault in the design can be expected to result in property loss or loss of life. I believe this means at minimum proper primary fusing, and secondary fusing where applicable, 94V-0 rated wiring and pcbs, a fully enclosed and properly grounded metal chassis, and in the case of a tube amp an optional tube cage. Thermal cut outs at strategic locations on heat sinks, and single event thermal fuses in power transformers add safety. I am sure there is plenty others can add here. Doing all of this demonstrates intent to sell a safe product.

In a lot of cases a product malfunction in the hands a well informed user is just an inconvenience if that user agreed to and understood the risk up front, and the damage is limited to the unit in question. It would be very difficult to defend against a product liability lawsuit initiated by a hostile former customer. I recommend at the minimum an LLC, however a lot of small audio businesses are sole proprietorships, and there may be mechanisms for protecting these businesses to some extent as well.

Keeping a technical file demonstrating what testing you performed and how all aspects of design are considered from an EMC/EMI and safety perspective is something others have mentioned and is equally important.

I would only CE mark items headed for Europe so that they do not get stuck in customs, beyond that I would not use the mark. Be sure you at least meet the spirit of the requirements that are relevant. (Power amplifier speakon or shrouded output connectors required if output voltages are not SELV for example.. )
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This why I dont sell complete equipment, I just sell amplifiers modules.

Then it is up to the final user to get it certified if it goes into production.


A good friend of mine, Hugh Dean (Aksa), have sell amps kits for years and now sell modules, it's very times consuming because not all buyers do have enough experiences to correctly assemble a kit or wire a module, so you need to assist them in all step and correct their error by emails replies.

Maby a module amp, in a ready made case, and the guys just need connect a power transformer in a back plug.



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Joined 2010
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Hi Gaetan
Agreed, since no-one could tackle all the bureaucratic requirements alone and without corporate levels of liability insurances and industry assistance. I could not believe how much was involved in gaining CE mark approval for simple incandescent tablelamps! It took some months for the authority to agree that EMC testing was not required!

There are many levels of sub-assembly for complete amplifiers before they can be classed as such. If you believe your clients are not sufficiently competent to even hard-wire connect modules and power, I guess you could have problems. OTOH, precut holes and mounted hardware with good clear wiring diagrams can head off a lot of problems and turn a daunting month-long labour into a pleasant evening's work. You really do need your customers to feel good about the experience.

Most kit suppliers leave the difficult metalwork, power and control circuitry up to your imagination and perhaps a few suggestions which is where you could gain advantage. I hope you are not discouraged and get your design out there where people can enjoy it.
An option is a mostly assembled kit with an easy to follow set of directions and limited support policy.

A nice set of directions can be found in the Hafler manuals

I built the kit in the mid 80s. The amp boards were already mounted to the heatsink/fan assembly and all I had to do was make the wiring harness. The manual clearly defined how to make each connection and dress the leads. I can imagine that there are some who would need excessive support, but Hafler's limited support make business sense. If you can't solve the problem in an email or two, offer to troubleshoot it if the customer ships it to you with a nominal fee to cover service and return shipping.
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