DIYMobileAudio.com Car Stereo Forum banner

At last! The Biketronics BT4180 amp review you've all been waiting for!

113K views 404 replies 63 participants last post by  Fizzy 
#1 · (Edited)
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: http://www.diymobileaudio.com/forum...stry-dogma/141216-higher-end-amp-sq-myth.html

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 :)
 
See less See more
2
#253 ·
Confirmed that the BT4250 is the same chassis footprint as the BT4180.

Mike at Biketronics shared a couple more pics! The power connecter has been upgraded from XT60 to XT90 connector able to handle up to 100 amps.

“Here are some pictures of the BT4250. The APx measurement shown is using the AP's optimizer where it finds the drive level for a given distortion (THD+N) - in this case 1%. Uses the OEM UcD 250's, has a larger transformer, off-module Vdr supply, per-channel gain control all in a very small footprint.”

No firm date but he did tell me they are working on car specific amps. Maybe (keyword maybe) something available end of Q4 2018 (Xmas time) or Q1 2019.

When it comes closer to fruition I’m sure he will be asking peeps here for some input.
 

Attachments

#273 ·
Project euphōnos

BT4250
RCA area opened up to allow larger RCA’s
XT90 power connector
8 gauge fused wire
40 amp fuse

Individual channel gain pots input stage has been forgone in the name of SQ to have a more direct and pure signal path. As a starting point I had Mike set the input voltage to 4 volts for the amp to be at “full tilt before clipping”. I will be using with a Helix DSP Pro that has 8v preouts (not specified if this is 8volt rms?). Mike is able to adjust the input voltage on the amps if you choose no gain pot stage.

XT90 connector is rated for 90-100 amps. The fused 8 gauge wire the amp came with is fused at 40 amps.

I put together a graphic that I asked Mike if he was able to laser in. In homage to the UcD modules, is the hypex electronics wave graphic. Then in similar line of thought as Biketronics’ allusion to ancient Greek mythology with its “Titan” Power reference, I put the Ancient Greek word εὔφωνος or euphōnos, meaning "well-sounding" or "sweet-voiced".
 

Attachments

#277 ·
Thanks for the detailed info and pics!

And yeah, I love those EA E7 RCA's as well. :)

For the system I'm currently working on, I would probably need one of the BT4250 and one or two of the BT4180 as well.

I guess these are made to be placed inside a fairing or in enclosed saddlebags on a HD, but do you think they'd have any problems heatwise buried under a rear quarter trim panel or in the sealed front boot of a Porsche 911?

Would love to have these included in the next high-end "SQ Amplifier Shootout". :)
 
#278 ·
Thanks for the detailed info and pics!

And yeah, I love those EA E7 RCA's as well. :)

For the system I'm currently working on, I would probably need one of the BT4250 and one or two of the BT4180 as well.

I guess these are made to be placed inside a fairing or in enclosed saddlebags on a HD, but do you think they'd have any problems heatwise buried under the rear quarter trim panel or in the sealed front boot of a 911 Porsche?

Would love to have these included in the next high-end "SQ Amplifier Shootout". :)
These things are of solid build quality. Once you hold it in your hand and feel its mini heft you’ll understand. As you mentioned these amps are were physically designed to fit in bike fairings or saddle bags where they would experience long periods of exposure to heat/sun. I think they should do fine given their 90% efficiency. Plus they have active cooling via 2 internal fans.

I too would like to see these in an amplifier shootout. Anybody in touch with Matt Hall?

These aren’t using GaN Fet tech like the SounDigital amps but these amps are near the pinnacle of Class D topology in regards to PWM and feedback filter design. Up there with the MMATS HIFi series that are based off the Infineon IRAUDAMP4 Class D design.

Very few amplifiers disclose the details about their Class D circuits. Biketronics uses Hypex UcD and I like that Hypex is more transparent about their empirical approach towards providing audiophile grade sound via the class D topology. *haha might need an electrical engineering degree/education to decipher it all but it’s out there at least.
 
#279 ·
Again, THANKS for the info and quick response.

Yeah, I'm curious to see the performance when more GaN Fet based amps come out.

From what I know about the Hypex UcD modules, I've heard that quite a few big manufacturers of both high-end and mid-level active/powered studio monitors are using them.

And I just realized that Mike has created and is working on a BT6180, so that along with one of the new BT4250 amps would be perfect for my setup. :thumbsup:

I believe that you can reach Matt Hall via the web site or respective Facebook page Link at...

Revelation Audio
 
#283 ·
Regarding a new SQ amp shootout, I doubt that Matt Hall will be doing any more. I thought I saw him post somewhere that while he may do some additional equipment shootouts, that because of his association with Revelation he wouldn't be publishing any more amp shootouts. I could be wrong, and it certainly doesn't hurt to ask him.
 
  • Like
Reactions: bbfoto
#287 ·
For what it's worth, for the last 3 years I have had two of the BT4180s running my front sound stage, and have had no issues whatsoever.

They sound great, and the tiny size was perfect for my stealth install.

One of the units I purchased used from a forum member, and one was new from the company.

Highly recommended!
 
#290 ·
I’ll be doing a write up/build log soon with all the details.

No spares at the moment. I opted to stack 3 amps together for a mini 12 channel beast! 2 BT4180’s and 1 BT4250. This powers 3-way front stage, 2-way rear fill, and a center channel.

I’m stashing everything in Civic spare tire/donut well. Don’t judge the rats nest of cables.. it’s an ever evolving personal daily driver project with a lot going on: Helix DSP Pro 2, miniDSP DDRC 22, miniDSP DDRC24, 2 x iFi itube2 preamps, and a passive crossover for a 2-way center so far :eek:

I also added Noctua external fans purely for peace of mind during the summer heat. Personal preference. Not really needed per Mike.

Stacked and mounted them using 3M SJ3551 400 Dual Lock strips. Which is more than enough in my scenario. My trunk is lined with MLV. The 3M product adheres like a champ. Similar to Resonix MLV compatible Velcro or SDS Velcro but the 3m Dual Lock is a firmer product which provides a desired gap for air flow between the bottoms of the stacked amps.

Specifically the 400 variant of the 3m Dual Lock provides the highest density of attachment points. A 400 to 400 attachment is a eerily strong attachment. I made the mistake of attaching 1 large 3”x2” piece to the Helix DSP Pro 2 on the middle of the unscrew-able bottom plate... I literally bent/warped the bottom plate before the 400/400 connection even budged when attempting to remove the DSP mounted to MLV. Smaller cut 1/2” to 1” square pieces in the corners of everything is a better solution so far.

https://www.ebay.com/itm/Free-Shipping-3M-2-x2-6-1-3-6-10-20-30-150-SJ3551-400-Dual-Lock/323056440726?item=323056440726&var=512178216105&ppid=PPX000608&cnac=US&rsta=en_US(en_US)&cust=7HG58405T91060424&unptid=c8e80960-503b-11e9-94e8-441ea14e0a7c&cal=9e506ceae9cd6&calc=9e506ceae9cd6&calf=9e506ceae9cd6&unp_tpcid=email-receipt-auction-payment&page=main:email&pgrp=main:email&e=op&mchn=em&s=ci&mail=sys&pageci=097a8da0-d6a0-4f0e-a427-b23c38704ee4

But all this works phenomenal like I said for my scenario when adhering to MLV. It will also super grip to cleaned metal. I haven’t really tested its adhesion to wood. But 3m makes other Dual Lock products with different adhesions so there is still probably a solution. I’m constantly swapping parts haven’t had any securement issues with various equipment using this method of attachment in a daily driver for the past 3 years. Everything stays put through the potholes, speed bumps, abrupt brakes, etc.

I can’t find the pics but I think Biketronics can put screw mounts that protrude from each corner if you would prefer a mechanical attachment.
 

Attachments

#291 ·
Awesome, Though kinda sucks in my install I need it to screw in. Could work something out though. If you know or hear anyone selling for good price please let me know. Also any chance you talked to him about us car guys? I doubt he would care until the winter with all the bike stuff. I saw some harley forum guys stating they do a $150 off Christmas sale?
 
#295 ·
Awesome, Though kinda sucks in my install I need it to screw in. Could work something out though.
I’m still searching for where I saw it but there is a pic floating somewhere. The Biketronics amps all have a screw in each corner on the bottom plate where attachment feet can be attached.

They can do it for you if you buy directly from Biketronics or you could fashion one from using 4 small/short black mending plates for each corner with a slightly longer screw to accommodate the plate thickness.
 

Attachments

#294 ·
I’ve wondered about that as well. Something along the lines of swapping 2 of the 250 modules from a BT4250 for 2 of the 180 modules. The BT4250 power supply would be more than capable. This could bring the BT4250 price down by a little as well as provide the often desired staggered power setup for front stages.

May take a minute to get an answer but I’ll see what I can get out of him!

I can't even comprehend what's going on in your picture :D
Yea it’s a lot. But there is a method to the madness. Give me a couple weeks more to work on it.. and I’ll tell the story of the source signal’s wonderful journey to amplification!:D
 
#297 ·
I picked one up on the Harley forum for a decent price, couldn't help it. Wondering if the puny power wires will be ok less than 6 inches to the block. Forgot about the mount feet problem. Will have to figure something there.

Spoke to Mike and he is about ready to have the car specific biketronics ready for sale
 
#302 ·
Don’t forget about the Deutsche Novello connectors. Makes the speaker wire situation a lot easier:



I’m running tubes with mine too. If you are still having noise after input gain adjustment it’s more then likely the tube stage introducing a noise floor.

Also for your mounting. I mentioned earlier about 3M Dual Lock...
Looks like Second Skin started offering the product. It will adhere to the amp and be a pain to remove. It will also adhere to cleaned metal very nicely.

I had a period though where I wanted to mount the amps to a MDF amp rack. I didn’t quite trust the adhesion to wood/MDF so I actually lined the MDF rack with a layer of MLV and viola.. I had solid mounting surface for the 3M Dual Lock to adhere to.

I’m not sure if what Second Skin offers is the 400/400 variant of 3M Dual Lock but that is the one you’ll want. Freakishly strong (more so than SDS/Resonix Velcro in some cases). It’s also more stable and secure as in no micro wobbles that can occur with Velcro products. Just some food for thought.

Nothing much to look at but I’ll attach some pics. It was literally my “drawing board” as I was deciding on gear. Amps/gear never budged during my daily driving activities as well as removing and placing the rack in and out of the trunk:

Back:


Front:


3M Dual Lock 400/400


Amps adhered to MLV on amp rack:


Attached tubes to amp via Dual Lock:


Sturdy amp rack that I removed and placed several times:




 
#306 ·
Anyone know when BikeTronics will have the car-specific amps ready to ship?

I'm in the market for another 4250 and 6180, but I'm curious what configurations the car-specific amps will be available in?





Those Novello connectors are nice and streamlined. :)

I think I might still prefer the small 15/30/45 amp Anderson Power Pole connectors, mainly because both ends are protected by the housing. They also keep a solid and consistent contact due to the spring-loaded interlocking system. They are still relatively small and you can connect the housings together into as many pairs or group as you need.







Here's some more notes from a supplier:

https://powerwerx.com/anderson-powerpole-connectors-30amp-bonded


"The 15, 30 & 45 amp contacts all use the same housing. Therefore, they all connect to each other. The size of the flat contact area is actually the same for all contacts. The only difference between the 15, 30 & 45 amp contacts is the size of the receiving barrel that accepts the wire...

15 amp contacts are recommended for 20-16 gauge wire
30 amp contacts are recommended for 14-12 gauge wire
45 amp contacts are recommended for 10 gauge wire

- Powerpole connectors are both genderless and polarized connectors
- Powerpole connectors are genderless, meaning the supply and load connectors are the same. Since there are no male or female parts, all Powerpole connectors mate with themselves.

- Powerpole connectors become polarized when the red and black housings slide together via molded-in dovetails on the housings. Connections can be quickly made and remade sight-lessly or in the dark.

- Unassembled vs. Permanently Bonded:

Unassembled sets can be assembled in any configuration. As two housings slide together via molded-in dovetails, two half rounds align to form a channel that accepts a slotted roll pin. This prevents the housings from sliding apart. The roll pin is a compression fit and will not fall out in operation.

Powerwerx now offers Red/Black Powerpole sets that have been ultrasonically welded together which creates a permanent bond between the red and black housings. This can save assembly time, guarantee correct configuration, eliminate the need for a roll pin and enable the use of Powerpole accessories such as retaining clips or block-lok clamps." - Powerwerx

The Powerwerx Power Pole Crimper is The BOMB. Definitely worth the money if you think you'll be doing more than just a few of these types of connectors!

They also supply Round and Rectangular Panel Mounts...


 
Top