Plate Amplifier FAQ
Thanks for considering NB Audio's range of plate amplifiers. Below you'll find some common queries we get in relation to our plate amplifiers.
What is the main use for your plate amplifiers?
The most common use for our plate amplifiers is for use in DIY single channel subwoofer builds.
Do you offer multi channel plate amplifiers?
Not yet! These are on the cards but we don't currently have a solid road map or release date.
Are your plate amplifiers airtight?
Unfortunately not, in standard form, our plate amplifiers are not airtight. For best performance, we recommend building a separate enclosure within or attached to your cabinet for our plate amplifiers. Especially in sealed enclosures. There are guidelines for these separate enclosures in our manual.
We are working on a seperate 'backing box' which can be purchased separately and combined with each of our plate amps to make them airtight without having to build a separate enclosure. The ETA for these backing boxes is currently 'TBC'.
What is the difference between your NPAXXX range and NPAXXX-8 range? Is it just power ratings?
The difference lies in how each amplifier is configured to deliver its power. While both versions share similar features and form factors, they’re optimised for different speaker impedances:
NPAXXX models (e.g. NPA500) use a single amplifier module and are optimised for 4 ohm speaker drivers, delivering maximum power into lower impedance loads.
NPAXXX-8 models (e.g. NPA500-8) use a dual amplifier module in bridged mode, which allows them to deliver higher power into 8 ohm speaker drivers.
What is minimum impedance your plate amplifiers can handle?
Our standard NPAxxx models (e.g. NPA500) are stable down to 1 ohm, and are best suited to 4 ohm speakers or lower-impedance loads.
Our NPAxxx-8 models (e.g. NPA500-8) are technically stable down to 2 ohms, however, there's an important nuance which is relevant to your Warranty.
Our NPAxxx-8 models are not designed for sustained high-power operation below 4 ohms. Running bridged amps below 4 ohms can lead to excessive heat, thermal stress, and potentially thermal shutdown or long-term reliability issues — especially in enclosed chassis like plate amps.
For this reason, our “-8” bridged models are recommended for 8 ohm speakers, where they deliver maximum performance without thermal limitations. If you're working with 4 ohm speakers or lower, we strongly recommend using our non-bridged amplifier versions, which are designed for that purpose and offer better thermal and electrical headroom.
In the event of an issue with your plate amplifier, we will ask what speaker driver you were pairing it with. If you were using the plate amplifier with a speaker driver which has a minimum impedance of below 4 ohms with one of our '-8' models, your warranty may be voided.
Advertised speaker driver impedances are rarely the drivers minimum impedance. Most 4 ohm speaker drivers will drop well below 4 ohms (as low as 2.6 ohms!)
If you're unsure, get in touch with us and we'll provide guidance.
Why does the NPA1200-8 have digital inputs and no high level inputs or manual gain adjustment?
Great question! The only reason we went down this path is for Hypex's native active cooling support which is built into the digital input module.
Due to the higher power output of the NPA1200-8, it requires a more advanced active cooling system via a fan. The software monitors the signal input and module temperature. a proportional–integral algorithm then controls fan speed. This ensures sufficient cooling when needed and quiet operation when desired.
This capability is not bult into the module that contains high level inputs and manual gain. But don't worry, you're not missing out on much as high level inputs are rarely used and gain can easily be handled on multiple levels digitally or with manually with the assistance of the remote kit.
Do your amplifiers have DSP?
Yes! Currently our full range (excluding the up and coming NPA2500) have DSP. We utilise Hypex's HFD software for our plate amplifiers.
We'll admit, the software does have a very steep learning curve but once you have your head around it, it's incredible what it's capable of.
Are your plate amplifiers with DSP FIR (Finite Impulse Response) Capable?
Yes! All our DSP plate amps are FIR capable.
FIR filters are digital filters that allow for precise control over both the amplitude and phase of audio signals. This capability is used for achieving accurate sound reproduction, as it enables the correction of phase distortions and the implementation of linear-phase crossovers.
What size and cut-out requirements are each of the amplifiers?
We’ll be releasing the full product details and recommended cut-out dimensions shortly. CAD files of the plate and basic 3D models will also be available shortly for integrating our plate amplifiers into your own enclosures.
How long is the warranty on your plate amplifiers?
Our full range of Plate Amplifiers come with a 5 year warranty.What sort of Customer Support do you offer?
Another advantage of buying from us is the direct local support. If you have any questions, you'll be in direct contact with me—the person who designed, assembled, and tested your unit.
We encourage you to read the manual prior to making contact, as most troubleshooting can be solved with the information in our manual, but if you do have further trouble, we're happy to help out!
Your plate amplifiers seem to be very similar to the FusionAmps offered by Hypex, which are a little cheaper. What are the differences?
You're correct! We use the same modules as the amps you'll find in Hypex's FusionAmps. The good news is, this also means performance will be very similar. However, there are benefits to our plate amplifiers which we feel justify the increase in pricing.
- The form factor is one of the more obvious differences. We’ve chosen a layout that we believe better suits subwoofer enclosures.
- Our amplifier plate is 20% thicker. While not as relevant for the NPA1200-8, which has active cooling, a thicker plate slows the rate of temperature increases and helps absorbs short term thermal loads.
- We provide a longer warranty. 5 years compared to Hypex’s 2 years.
- Local support. Hypex handles support via email across time zones, whereas we’re available to talk directly by phone when needed.
- Warranty claims are handled locally. Hypex amps often need to be sent back to the Netherlands for repair or assessment, which can be a slow process. We manage all warranty claims in-house at NB Audio. If there’s an issue, we’ll replace the module and get the amp back to you quickly. We deal with the Hypex warranty process separately.
- Our plates are made locally, and we assemble and test each amplifier here in Australia. It’s a small but meaningful contribution to Australian manufacturing, keeping jobs and dollars onshore.
- Higher powered models in the works. FusionAmps are limited to a certain range of Hypex modules. We are working on models that use a different range of Hypex modules which offer significantly more power.
- Custom options available. We're happy to work with you to tweak the shape, colour and add custom engravings to your plate amp (within the constraints of the module footprints) to suit your enclosure design and intent. Find out more here.
For some, these differences justify the added cost. For others, maybe not. Either way, you’re getting a top-tier amplifier using trusted Hypex modules. We’re proud to have their backing and grateful for the guidance they’ve provided throughout the development process.