The DS505BLHV servo is the most highly developed iteration of our most popular servo ever!
This all-alloy standard-size servo is equipped with a brushless motor and has an all-steel gear train. This makes it powerful and very durable. But more than strong and fast, it centers really good because we use the Noble 1mc potentiometer. This Japanese pot is the best on the planet (and why we use it).
So because we've been making this servo for more than a decade (and have produced tens of thousands), it's a well proven design, which ends up being a superb all-rounder in the 500ozin class. Means using it for giant scale model airplanes, huge hydros, and 1/5th scale trucks . . . after all, there's no such thing as an airplane-servo, truck-servo or a boat-servo since servos don't know in what they're being installed. Nor care.
Bottom line? Some say the DS505BLHV is the best bang for your buck in the whole world, for any application, and at any price. Big words? Well, yes, but here's why.
First, please allow a brief birdwalk regarding ProModeler model numbers because you can interpret them without a decoder ring. In short DS505BLHV means . . .
- DS = Digital Servo
- 505 = torque rating in oz-in
- BL = Brushless motor
- HV = High Voltage (to 8.4V)
Regarding HV . . . just as DS means digital servos, HV distinguishes high voltage servos from 4.8V or SV servos (SV for standard voltage). How this came about is interesting and germane. You see, back in my day (early 1970, call it +50 years ago), all servos were 5V devices (based on 4-cell battery packs) so we didn't call them SV servos. Heck, we didn't actually call them anything simply because all servos, all brands operated on the same 4.8V standard as created by 4-cell packs. These battery packs relied on NiCd cells (nickle-cadmium chemistry), each of which made 1.2V/cell (as opposed to non-rechargeable AA-size Alkaline cells, which makes 1.5V/cell). This i important because one segment of the sport relied on supplying a 4-cell plastic holder in which the user was expected to supply on his own hook four AA-size Alkalines. So four Alkalines making 6V (1.5V/cell x 4-cells = 6V) instead of a 4-cell NiCd battery pack. More in a bit.
These were packs, by the way, which took 1.2V/cell and wiring four of them in series (where the (+) terminal goes to the (-) terminal of the next cell until you've done all four cells) and resulted in 4.8V battery pack. This expressed in math as 1.2V/cell x 4-cells = 4.8V but we refer to it as 5V (nominal) because they come off charge a bit hotter than 4.8V. Note; 5V is an incredibly common voltage within consumer electronics (yes, even to this day). For example, open any PC on the planet and you'll see both 12V and 5V leads coming off the power supply!
Anyway, one day a fellow tried a 6V pack on his 5V servo and presto the servo output more that the rated torque (on 4.8V) and it was faster, too. So the guy gets all excited and is loving how much more powerful and fast the servos are until one burns up and he crashes - oops! Note; how he made 6V is by using 5-cells instead of four because 1.2 X 5 = 6.
Point being, as soon as he told one guy, who told the next guy, and before you know it, the concept of using 6V instead of 4.8V spread like wildfire throughout the modeling community. And there was confusion because some servos lived fairly well, others failed very quickly. And because all this happened before the Internet, it took time to suss out which did best and which were terrible candidates for the approach.
However, one this for sure happened and once modelers caught wind of this, it almost instantly created demand for actual 6V-capable servos because a) modelers wanted more powerful/quicker responding servos, and b) manufacturer's always follow the money. So manufacturers then began making 6V-capable servos to satisfy the demand and life was good.
Of course, one day some guy thought, 'Well, if some is good, is more going to be better?' and tried running a 6V servo on 7.2V and presto, same thing happened as before. It worked and was even more powerful (and faster) until once again, it burned out. And again, the manufacturers responded by creating servos capable of handling 7.2V. And needing a name for the product to distinguish it from 4.8V or 6V servos, the industry settled on using HV as the moniker. And ProModeler were involved in this because we were new to the game and decided to avoid producing standard voltage servos altogether because it was obvious these were on the way out.
What we did, instead, was produce servos capable of being used on HV and SV, both. A so-called wide range voltage, a moniker that briefly stuck but was soon abandoned. What has survived is HV, and that's it. So how did he make 7.2V? Same way, but this time instead of a 4S or 5S pack using NiCd cells, he made a 6S pack because using the same math, 1.2V/cell x 6-cell = 7.2V.
The one day, someone thought of using two LiPo cells instead because at 3.7V/cell, two of them in series worked out to 7.4V (3.7V/cell x 2-cells = 7.4V). And because 2S packs are cheaper to produce, this sounded the death knell for the whole NiCd industry and that chemistry quickly fell out of favor. It happened almost overnight. And FWIW, this also led to the demise of 6-cell and 7-cell racing of RC cars and trucks and thus was born 2S, 3S, and 4S classes using lithium based chemistry, instead.
This business of changing over from nickle-cadmium based chemistry to lithium-based was a sea change, a big deal in the industry (and throughout the world as consumer electronics) and everybody switched over as well. For example, the hand-held transceiver we carry in our company plane uses lithium instead of nickle-based, also. Did the cell phone industry and laptop computers.
So just like that, we were off to the races making HV servos. Especially as it turns out, a pair of LiPos at 3.7V/cell were so close to a 6S pack using NiCds cells making 7.2V (so 7.4V vs. 7.2V nominal). Note, a 2S LiPo pack fresh off charge makes about 8.4V and this becomes important.
And to distinguish these servos from ordinary ones, the moniker HV came into usage, which is where we are today. But it gets more complicated. You see, to lower their manufacturing costs for RTF and RTR models (Ready To Fly and Ready To Run), the manufacturers (for example, Traxxas) ingeniously added a circuit to their Electronic Speed Control (basically, a voltage regulator circuit) to parasitize (steal) juice from the propulsion pack making 12-15V in order to power the control electronics (receiver and servos) with 6V or 8.4V. And the advantage the manufacturer was obvious, as now they only had to supply one battery instead of two separate batteries (one or propulsion and another for control. So in one fell swoop, a cheaper solution was created (and some engineer took home a nice Christmas bonus for thinkiing up the idea). This, of course before they hit on the idea of charging you for the one battery the way they do it now!
Anyway, this circuit was called a Battery Eliminator Circuit, or BEC. And modelers for this class of model (typically using 3-4S LiPo packs) loved it because it meant they only had one battery to charge instead of two. Great, right? Maybe. Why maybe? You see, the BEC is only sized for the servos they supply, which is perfect for ordinary modelers but more advanced modelers, the ones who want more powerful servos were put in a bind and many didn't even know it because a more powerful servo will work when powered by a BEC but not to the servo's rated performance because the manufacturer of the BEC created the circuit for stock servos, not for more powerful ones. The issue isn't the amount of voltage supplied by the circuit but the amount of current flow (this is measured in amps). Houston, we have a problem!
were happy, modelers (advanced modelers) preferred to use more sphisticated servos (more powerful and faster). ! stole a Control - except - because some rigs are running 3S packs, a hobby dealer went to an Asian manufacturer and said, put my brand on a servo and I want ti to run on 3S (technically 11.1V but in reality, 12V). And since manufacturers are all about the Benjamins, they did it. Only thing is, hobby dealer isn't an engineer, he's a businessman and decided to try and 4S packs (and now many are using 6S and 8S and even 12S,
So with model airplanes and helicopters with internal combustion engines, using a 2S pack for the control electronics is incredibly common because before that, they used 4S and 5S packs using NiCd cells instead of lithium-chemistry. Note; this is why we offer 2S lithium type packs ranging from 650mAh to 6000mAh.
Thing is, in the model car/truck world, electric-powered models dominate, meaning 95% of the market. The other 5% (or less) being high-end gasoline-engine powered models like what MCD Racing offer in an RR5/XR5, Losi 5ive, or Primal RC Raminator). and with a gasoline engine), they
, meaning 4-cell or 5-cell NiCd. Use a 2S pack with a standard voltage servo and it would quickly go poof and release the magic smoke
you know how a Porsche 911 from 2009 and 2019 are recognizably the same car? This, despite a decade between them! Yet if you park them side by side they are 'totally' different cars, right? This is because Porsche engineering evolves their designs (little known fact, the first one hit the market in 1963).
So basically, ProModeler have the same engineering philosophy as Porsche because we're doing the same thing. We introduce iterative improvements to our original 420oz-in servo. And just as Porsche 911 had a 2.7L engine, then a 3.3L, then back down to 3.2L displacement, we also use different servo motors. And always with the same goal, to make a better servo!
This brings us to the next step in the DS420BLHV evolution, the availability of a more powerful motor, leading to our introducing the DS470BLHV. Basically the same servo, ever evolving like Porsche does their 911 supercar, (even the same price, $100, which Porsche doesn't do).
Then our motor vendor approaches us about another motor. This leads to a further evolution as the servo becomes the DS555BLHV. So now we have a further advancement as this servo has become the DS505BLHV? Less torque? Yes, but a better motor meant the tradeoff was worth it in the eyes of engineering. What makes it better is about math, and beyond the scope of this description but just as Porsche engine displacement has varied up and down, torque output for this servo has now also gone up, up, up and now down. Bottom line? better servo. Best it's ever been.
Where can you use it? A lot of places. Pretty much any 3D airplane to mid-size, call it 96" with a DA100. IMAC models to 104" with a DA120. Obviously, even a 40-size trainer since the physical dimensions are standard size even though the price of a single servo approaches the price of the whole airplane, but who knows, maybe the fellow has plans to build a big ass gasser once he learns to fly. Not our business.
Where else? Pretty much any helicopter in existence that uses a standard size servo - 600-class, larger 700-class, and even 800-class are going to be perfectly served by this servo.
Surface use, both land and sea. On the water, this is an outstanding servo for big hydro models for steering at 80mph. Surface use includes any 1/8-scale racing buggy, crawlers like a TRX4, etc.
There are several servos on the market in a similar performance range. Popular ones include;
- Futaba S9177SV and BLS177SV
- Hitec HSB-9381TH
- MKS 777+
- Savox SW2210SG
Futaba S9177SV is a generally very well made, high quality servo featuring a hybrid case (polymer/aluminum) and a coreless motor. Equipped with steel gears like the DS505, it's priced in the range of $180. If you want a Futaba servo, but with an all-alloy case and brushless motor like ours, then you'll have to pony up more money (to the tune of $240) for the BLS177SV, instead. Theirs both makes 65oz-in more torque than a DS505 - but - are a tick slower. If the torque is critical, eyeball our DS630BLHV. Honestly? It's hard to go wrong with either Futaba product - but - we feel ours give them a good run if you're interested in a solid alternative.
Hitec HSB-9381TH is a very nicely made, high quality servo featuring an all-alloy case and brushless motor. At $190 it's very similar to the DS505BLHV in terms of torque (a tad less powerful at 472oz-in v. 505oz-in), but while this is a difference we can measure in the lab, in the real world, it's insignificant (in our opinion). However, at 0.14sec/60° it is considerably slower than the DS505 (which is a 40% faster at 0.094sec/60°). While the speed difference is of no consequence in a scale or sport model, its a definite disadvantage for the pilot of a 3D model of any kind (or on the race track). A further disadvantage - in our view - are the titanium gears. In general, titanium is a wonderful metal for an SR-71 Blackbird flying +2000mph, but it's much softer (and more brittle) compared to steel gears, which wears faster. In demanding applications, what you're going to find transmitting the power (like a money-is-no-object Ferrari F1 race car or on the track at a NASCAR event), the material of choice is steel for the gears, never titanium. While titanium 'is' better in the eyes of marketing (vs. engineering), it's because like carbon fiber, the word titanium gets rubes reflexively reaching for their wallets!
MKS 777+ is a very nicely made high quality servo featuring a hybrid case (aluminum upper, polymer lower, with an extruded aluminum center). It lacks cooling fins and when compared to our case, which is CNC-machined from a solid billet of 6061-T6 aircraft aluminum, it's no contest in the ability to shed heat when the servo is working hard. Simply put, ours is better. Priced in the range of $130, it also has a coreless motor (like the Futaba S9177SV) instead of the superior brushless motor like we use in the DS505 (as so Hitec for their 9381TH and Futaba in the BLS177SV). Like the Futaba, this one is a bit more powerful than ours (by 55oz-in) and we have the same advice, if that's enough to move your needle, consider the DS630BLHV, instead. But like we said with the Hitec, these are differences you can measure with an instrument, but in a model? Not so much. Note; if you're not familiar with what's in it for you when selecting the motor that powers your servos (like coreless vs. brushless), then review this article titled; About RC Servo Motors because we actually cut motors open with a lathe and show you! Facts are, it's what's inside that makes them different, and this determines what's better for you (but in general, any brushless beats any coreless). Speed-wise this servo is a close match - ours is a tick faster at 0.094sec/60° versus 0.10sec/60°, and this is a slight advantage for 3D-maneuvers and racing, but of no consequence for scale and sport flying, otherwise. However, a serious downside in our opinion is the 777+ is equipped with titanium gears instead of steel.
Savox SW2210SG is a finely crafted servo featuring a brushless motor but, perhaps to hold down the price ($108), they opt for a hybrid case (polymer upper and extruded aluminum center). This means no cooling fins and significantly weaker in terms of resisting abuse (all-alloy case is where our DS505 as well as the Hitec 9381TH and Futaba BLS177SV spank the Savox). Performance-wise, it's a fair match at 500oz-in versus 505oz-in for ours (indiscernible in any model), but at 10% slower ( 0.11 sec/° vs. 0.094sec/60°) - nothing important in a scale model or monster truck, in any kind of high performance application like 3D-flight or on the race track . . . faster is always important. This servo is equipped with good quality steel gears, so it's macht nichts when choosing between theirs and ours if you're only looking at the gears since they're both essentially in the same league in this regard. Bottom line? This Savox servo is quite decent and definitely worthy of being on this list of servos compared to our DS505BLHV but it's absolutely not better.
We hope this honest take on how some top competitors stack up is of some use. Click the links and you'll see a new tab open so you can look them over and not loose your place here. Anyway, if you feel you know a servo worthy of being on this list, tell us and we'll take a look. reach out to us at: info@promodeler.com or via; 407-302-3361 because we're all ears!