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Discussion Starter · #1 ·
I've narrowed my choices down to either a Hsu ULS-15 or a Rythmik F15HP, and I'm torn between the two. After tax and shipping, they're almost exactly the same price ($5 difference).

I haven't had a chance to listen to either of them, which would make the choice simple, so I put it to you. Between the two, which would you have?
 

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Rythmik if I was choosing. The servo driver is what makes it more appealing to me.
 

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To be contrary, i'd go with the HSU. lol


I feel if the servo was all that, then there is no reason why it wouldn't be incorporated into bigger brand subs. I think it's more marketing than a large difference (if any) between servo and non-servo.
 

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I'm not even sure why you're comparing a huge ported sub to a smaller sealed sub to be honest. The FV15HP vs the VTF-15 would make more sense.


Without understanding your room size, how loud you like to listen, etc., kind of hard to say.
 

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Quote:
Originally Posted by sputter1 /forum/post/20876770


To be contrary, i'd go with the HSU. lol


I feel if the servo was all that, then there is no reason why it wouldn't be incorporated into bigger brand subs. I think it's more marketing than a large difference (if any) between servo and non-servo.

Servos are not all alike. Velodyne has been using servos in its best subs for many years. In combination with other circuitry the Velodyne Servos (like the DD-18), can't be made to sound bad. Distortion is limited to under 10%.


The Rythmik servo seems to be an ingenious design that doesn't add much to the cost of their subwoofers.


Many owners of Rythmiks find the sound to their liking. But please feel free to buy any sub that floats your boat. But if you haven't acutally heard a Rythmik, that takes away from your comments.
 

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Quote:
Originally Posted by spyboy /forum/post/20876939


Servos are not all alike. Velodyne has been using servos in its best subs for many years. In combination with other circuitry the Velodyne Servos (like the DD-18), can't be made to sound bad. Distortion is limited to under 10%.

I've had a Velo 18 in the past(still have it collecting dust) and it may have reached it's specs, but in noway, imo, was it able to come close to the performance of my Rythmiks. I thought the Velo was slow and sluggish and just not very involving.


I have to agree, not all servos are alike.
 

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Quote:
Originally Posted by sputter1 /forum/post/20876770


To be contrary, i'd go with the HSU. lol


I feel if the servo was all that, then there is no reason why it wouldn't be incorporated into bigger brand subs. I think it's more marketing than a large difference (if any) between servo and non-servo.

You may think it's marketing but you should hear one first before you dismiss it.


Both Velodyne and Rythmik have multiple patents on their servo design, so it's not like anybody can copy their design and add servos to their subs.


I don't see any reason to buy the ULS over the F15 unless you really want the wireless option. That is the only real advantage I see that the Hsu has over the Rythmik. The F15's amp has more features/controls for fine tuning the response (PEQ amp)
 

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Quote:
Originally Posted by warpdrive /forum/post/20877625


You may think it's marketing but you should hear one first before you dismiss it.


Both Velodyne and Rythmik have multiple patents on their servo design, so it's not like anybody can copy their design and add servos to their subs.


I don't see any reason to buy the ULS over the F15 unless you really want the wireless option. That is the only real advantage I see that the Hsu has over the Rythmik. The F15's amp has more features/controls for fine tuning the response (PEQ amp)

+1. If wireless isn't an issue then the Rythmik would seem like a no-brainer to me.
 

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Quote:
Originally Posted by rkl525 /forum/post/20876948


The F15 isn't ported, the FV15 is. The HP behind both models denotes the more powerful amp, and different driver.

Ah, didn't realize that (wasn't even aware Rythmik had the F15 in an HP version so figured it was the FV15HP).


OP (if you're even still listening), you're looking at two subs that are almost identical in size, the Rythmik has potentially a slight 1" advantage (i.e., larger) there in a couple dimensions, both have 600 watt amps, and both are 15" drivers in a sealed box, and both are almost identical in price. Question comes down to how heavily EQ's are these subs and where? It seems both are given they are flat to 14/15hz anechoically (I'm assuming that is what their spec is) depending on the option selected. So both are likely going to peform quite similarly.


If you ascribe to the "servo" technology is better crowd, or want to try it, go for it. Admittedly I also like the fact that Rythmik posts the T/S specs of their driver on their website (due of course to the fact that they sell them separately). The Rythmik also has an aluminum cone, FWIW.


On the other hand, if you really need wireless, go for the HSU.


Otherwise, choose the one that looks best to you, because they are going to perform quite similarly and you'd likely not be able to tell the difference without having both side by side playing the same material, and even then it would likely be difficult.


The Rythmik may play more "controlled" with the Servo technology, i.e., it may reduce distortion by not permitting the sub to play beyond its means. But admittedly I don't know much about servo technology and that's best left for someone other than me to explain!
 

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The Rythmik's servo technology is pretty well known, but to speak up for the ULS (I am such a ULS fanboy), it uses XBL^2 motor technology which is more difficult to explain to a layman then the Servo's feedback technology. Its advantages are much less distortion than typical driver design and also greater linearity. You can read about it here . I don't understand it very well myself but here is a fairly accessible explanation of the strengths of this design:

Quote:
think about a magnet reacting to another magnet. The most strength will naturally occur when the magnets are closest together, and become weaker as they move further away. Similarly, in the case of a speaker, you have a fixed magnet and the voice coil, in which the coil is an electromagnet. They will either repel or attract each other with current applied. With a typical speaker, the center point of the motor (permanent magnet) is where the strength is focused, and at rest, the voice coil is centered in that. As current is applied, forces either repel or attract this, moving the coil up or down. As you can imagine, as it moves, less and less of the voice coil is retained within the gap, so magnetic control over the entire voice coil is reduced. The idea with these motor designs is that the longer the coil, the more there is to apply strength to, so you'll get more excursion with a longer coil. XBL^2, from a functional standpoint, has two or more points that focus strength over a narrower gap, just think of it as two magnets, and as the coil leaves one gap, it will enter another, which allows a higher level of control and motor strength than if it were one. As the coil moves further from one gap, it moves closer to the other, so you will have more control over the coil since you are always within a strong point of flux, and you will get more motor strength over the excursion limitations.
 

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Discussion Starter · #17 ·
Thank you all so much for the input. I'm gonna go with the Rythmik. It just seems to get more praise, and there has to be a reason for that. I can't wait to hear it for myself.
 

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Quote:
Originally Posted by warpdrive
...I don't see any reason to buy the ULS over the F15 unless you really want the wireless option. That is the only real advantage I see that the Hsu has over the Rythmik. The F15's amp has more features/controls for fine tuning the response (PEQ amp)
Maybe:


Magnetic Grill

XLR connections

Additional 2 year warranty on the Driver


Both are great subs.
 
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