At last, the Biketronics BT4180 review!!! This has been months in the making; thankfully my day job has slowed down enough due to the holidays that I can finally write this without distraction. I’ve also attempted this review a few different times and scrapped each draft. It is difficult to write a review on amps given how polarizing amp SQ is. With that, I only have two guidelines for this thread:
1.) I am not here to convince you that amps sound different. No one ever wins these arguments, we might as well start talking about religion or sports team loyalty. Literally no one has ever changed anyone's mind regarding any of these topics by arguing online and I am not about to attempt this impossible task today.
2.) Please do not argue about our ability to or lack thereof to hear a difference between amps. If you believe we can hear a difference, awesome. If you do not, guess what, I have an area in this review for you as well. If you want to argue this topic, please see the Higher End Amp SQ Myth thread here: HIGHER END AMP SQ IS A MYTH
Now that we’ve performed that bit of housekeeping, let me first introduce you to the company known as Biketronics:
Years ago my mom told me that she and my father had some friends who built and sold parts for Harley Davidsons in my hometown of Moscow, ID. I’m not a huge fan of motorcycles and especially Harleys so this piece of information went in one ear and out the other. Fast forward to the summer of 2012, I was back in Idaho for a friend’s wedding when another one of my closest friends from high school called me up saying he had the field trip of a lifetime for me. He said it was a small electronics manufacturer and proceeded to tell me that they were building some really cool niche market audio equipment. Audio field trip? Don’t have to tell me twice about such an offer. I was extremely excited, especially given the escape from wedding preparations.
The next day we ventured down to the end of a large metal commercial building. It looked like where you see startup body shops or small town gymnastics studios; the affordable commercial mini mall. We went inside and were greeted by their purchasing director who gave me a personal tour of the place. It was BUSTLING with activity, people working on PCBs, taking orders over the phone, packing up shipments for UPS, etc. They were obviously very busy and outgrowing their space.
The director showed me all sorts of cool stuff. Woofers, tweeters, power supplies, amplifiers, even funny stories about a speaker “torture chamber” that he built to simulate intense heat/cold/humidity. That was an interesting discussion as I learned that the most resilient speakers he had ever tested were the HAT Imagines which took extreme head/cold/humidity with ease for a 24 hour period as it played at maximum output and did not skip a beat. Meanwhile he had destroyed the likes of Focal, Rockford Fosgate, and many other speakers with this same testing as well as many micro amps from other manufacturers (Rockford’s “boosted rail” amps were a dirty word there given how quickly they go into limp mode even with easy loads). This was my first real exposure to HAT which would later lead to me installing Unity components in my wife’s Jeep Grand Cherokee. His dedication to testing and finding the best products for his end customers was fascinating.
At this point in 2012 I had avoided the car audio world since departing it in 2004 to focus my time and money on finishing school and subsequently starting my career in the Seattle area. However, I had just recently re-entered the DIY home audio hobby about 6 months prior and I was in the process of evolving my active 2 channel speaker system loosely based on the Linkwitz Orions. I was using a 6-channel Rotel RB-976 for my amplification but I had been learning a lot about a company known as Hypex based in the Netherlands, mostly from extensive reading on Class D - diyAudio and Hypex Owners Circle. I was extremely excited to recognize Hypex modules on the purchasing director’s workbench. Even some modules I did not recognize, known as the UcD100OEM which they used in an older model of their amp. He began to tell me about these amazing little amps and how they are nearly 100% efficient, highly tolerant to volatile physical/electrical conditions, incredibly good noise rejection, tiny footprint, etc. I was considering building my own Hypex amp for home use but it had never occurred to me to use them in a car, though it made perfect sense.
Suddenly it occurred to me that these were my parents’ friends! Except they didn’t build just normal parts for Harleys, they were building audiophile grade packages for these bikes. First, I had no idea that there was such a market for high end audio gear. And second, I was extremely impressed with how much they did in house. They build the 12v power supplies, input stages and cases all there in the same facility before installing the Hypex amp modules for final shipping. What a small world it is!
Over the last ten years my mother’s health has been quite a roller coaster. She’s undergone numerous surgeries, emergency room visits and even a week in ICU with 50/50 odds of living. Like many mothers, she has a very stubborn side and sometimes needs a little coaxing to seek out the right medical assistance. Additionally, I am the only family member that she typically listens to and so I decided to move back to the Idaho area to help guide her on a path of recovery for her conditions. This meant I was also going to be local to Biketronics! Not a bad side benefit and fast forward to today, my mother’s health is very good now
During the 10 months that we lived in the area I came to know the owners very well. They had since taken over a retired Honda dealership which was ~20x larger than their old space, though last I visited only a few months ago in August, they appeared on track to outgrow that space as well! At the time, when my schedule permitted I would also attend a Tuesday evening session they would hold at their headquarters for anyone who wanted to come talk tech and use any of the tooling there to streamline prototyping of their own projects. An especially priceless offering for the many nearby engineering students at the University of Idaho and Washington State University. In fact, this open-door facility is formally known as their “Fab-Lab”, first announced here in 2010: BIKETRONICS OWNER DREAMS OF A FAB LAB IN MOSCOW. - States News Service | HighBeam Research
And most recently for winning an award in June of this year, reported here: Palouse Knowledge Corridor | Palouse Knowledge Corridor award highlights local entrepreneurs
In June of 2013 we finally moved back home to the Seattle area after seeing my mother through to good health. We were sad to move away from Biketronics; my wife was managing their logistics department and I was visiting on a regular basis, tinkering with amps with the owner and eating as much Mexican food as possible, prepared by one of their employees, Maria, who is from Mexico. To this day, Maria’s homemade hot sauce is still the best I have ever had.
After our return to Seattle we remained in close contact with the owners. I was having issues fitting amps in my truck, there is literally no space in these Hummers for anything, it is pretty ridiculous. The factory amp location is only 10”x10” so I did not have much space to work with. It finally occurred to me that I should try a Biketronics BT4180. At only 5”x7” I could even fit two of them. Here’s my current BT4180 installed:
Mike Meehan, the owner, sent me a BT4180 to test and it only took 15 minutes to install thanks to its small size and simple spring terminals. Only a fine-tipped object is required for installation to depress each spring terminal while fitting each wire. Super simple and RCAs attach with ease as well.
Each BT4180 is built with four UcD180OEM modules, an input stage which converts the single ended inputs to differential for the UcD modules and then their own homegrown power supply which converts 12v to the high rail voltage required by the UcD modules. Here’s the inside of my BT4180 which shows how well these utilize their diminutive cases. Notice the four UcD modules on the left, custom power supply on the right, input stage board on top and then two cooling fans on the far right (which I have never heard turn on, even on 4-5 hour drives at high volume):
For those of you who believe all amps sound the same, here are the objective benefits of this amp:
1.) Zero noise, even at high volume. Literally the lowest noise floor I have ever worked with in an automotive environment.
2.) Huge power output. Even at very high volumes driving my Dynaudio Esotar 650 mids and CSS LD25X tweeters, I have never been able to send the amp into clipping. With 180wpc RMS@4ohms, this amp definitely meets or beats output of the top 20 percentile of amps on the market. I haven’t seen an amp move my Esotars as much as this does. Tons of midbass kick.
3.) Small, smaller than the smallest USPS flat rate box. You could probably fit 3 of these under most seats. You could even fit one of these in some dashboards, one could easily fit behind my P99 in my truck.
4.) Easy to set up with the spring terminals. No gains to worry about. The Hypex modules can take a huge signal without clipping yet need a very small signal to reach full power output. I have no idea how they do this but it just works…kind of nice for people who do not want to worry about calibrating gains. It is a great match for my P99 which was able to gain down its own outputs during the auto-calibration process, further lowering the noise floor.
5.) Efficient, these are made to create full power on a Harley charging system. You can run a few of these in a typical car without needing to upgrade your electrical. Great for high end installs where the stock electrical system must be utilized (expensive/exotic cars, boats, etc.).
6.) Lifetime warranty…wow!
My subjective listening impressions:
1.) Crystal clear sound at all volumes. Even at very low volume, music sounds clearer than any amp I’ve had in here before. I can make out lyrics even when I turn it down. Something that wasn’t ever quite possible with other amps I’ve had in this truck. Could be a function of the higher power output but basically it translates to better perceived clarity.
2.) Big sound. Other amps I have used sounded a bit more narrow or hollow. The BT4180 creates a sound stage that feels large and enveloping.
3.) More dynamic…again, probably thanks to the higher power capability.
4.) Neutral sound…I’ve never been a huge fan of overly warm amps because of the amount of distortion that seems to be added in the midrange at higher volumes. The BT4180 lets you just crank it louder and louder while remaining absolutely crystal clear. No biases at any frequencies and no perceived distortion. Very transparent to the music.
I’m hoping to have a response plot available to post soon after the team at BT throws one of these on their Audio Precision analyzer, though I know prior versions have tested ruler flat from 12hz-20khz+. Yes, flat down to 12hz at full power, no smoothing. Meaning one of these could be used to drive subwoofers with ease. Which I am planning next for a pair of SI BM MKIV 12’s under my back seat, driven by a BT2180 (2 channel version of the BT4180). I am planning a similar setup in a Mustang Cobra convertible this spring to keep equipment weight/size to a minimum for improved performance without sacrificing sound. In fact, I really have no reason why I would use any other amp from now on. They’re certainly not the cheapest amp around but being made in the USA and the lifetime warranty are two great features that help justify the investment.
Bottom line, even from a purely objective perspective these are the best amps I have ever used. I recommend them for anyone with the right budget available. Though Biketronics is very well known in the motorcycle market, they are relatively unknown in the car audio market. To help them get the word out, I am organizing a group buy so please PM me if you are interested in an amp (or two or three). I even have two extra BT4180 amps in case anyone can’t wait for the group buy (originally purchased for my wife’s Jeep but we are returning it to stock before selling it later this year to upgrade to a full size SUV). Both brand new sealed in box with full warranties.
There are a few more of these amps in the possession of some prominent members here who will likely chime in with their listening/ownership impressions as well.
Thanks for reading!
EDIT: I TOTALLY forgot to mention that these have a VERY steep filter at 45hz which drastically reduces the amount of warrantied speakers that Biketronics has to deal with. I'm working with the owner to get these removed from a BT2180 for subwoofer usage, stay tuned