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please help me decide how to use my free subwoofer

R

rockin1150

Super Member
I received a velodyne f-1500r subwoofer (servo controlled) for free the other day because the plate amp was bad. the replacement was around $475 so that is outta the question on a free sub. I have no idea what to do besides gut the amp out and run an external amp to it. the 15" driver is really heavy and well built as well as the cabinet. I wondered how a person could make use of such a nice sub, but still not have to come out of pocket too much. I went ahead an wired it direct from the 15" woofer to a denon receiver (my test dummy) and the results were horrible, because I have no way to cross the woofer over, so it just distorts and sounds like **** even with 130wpc going to it. At one point it even shut the denon receiver down (protect mode) thankfully, it came back alive afterwords. I guess I am in need of a monoblock amp? maybe 150-200watts? I understand all of that fine, but how do I cross this sucker over? active crossover? :scratch2: I am thinking about picking up an old Audiosource amp/oneA that can bridge mono down to 200wpc @ 4 ohms. That may take care of the amplifier needs, but the yamaha receiver I use only filters anything above 200hz on the sub-out jack. I am thinking that will be way too high of frequency for loud listening levels, and I think optimally you would want a way to match the bass with a frequency control. thx for any advice :thmbsp:
 
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Does sending too-high signals to the driver put it in any peril?

Is a plate amp such as this worth repairing?

OP: where are you located?
 
I dunno, is it possible to use a servo controlled sub without the servo control hooked up? I have a HGS-10 that has a separate connector for the servo on the amp, which I'd imagine your F-1500R has something similar.

John
 
And the dead amp probably had some sort of EQ built into it to compensate for the small box. You could find out the T/S parameters of the driver and build a bigger box for it, ditch the servo and most likely have a killer sub.
 
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Go buy any plate amp rated to the raw speakers impedance from ebay for uber cheap. Would be well worth it. May not be "exactly" tailored to the response or box size but it will likely work quite well. That or get a passive low-pass filter and a amp you can run mono output from.
 
well, I did disconnect the servo drive (4 prong connector that goes to the accelerometer in the woofer. I figured this is a normal 15" woofer with a 87oz magnet, but when I connected the plate amp from an 8" ht subwoofer, it came on and sounded ok, but I could hardly get the driver moving any air, before major distortion occured. I don't think the sub is special in any way, just has the extra guts inside it. I cannot seem to yield any real results with both amp's I have tried. I know the impedance of the woofer is 6 ohms on my DMM, and it just seems like I cannot get enough power to move this heavy coned beast. I think the plate amp for the yamaha 8" sub I used was about 75wpc rms. wouldn't that be enough to move a 15" woofer a bit? maybe I just need to wait for a mono-block power amp to try.... I could salvage the woofer fine and use another box, but maybe this one could work? it is a heavy built box, and sounds good until it distorts like mad.
 
hopefully the problem is not the speaker itself ! if the amp was bad there is a chance the speaker is what did it in, had my share of that happen, mostly in car audio though.
 
rockin1150 said:
well, I did disconnect the servo drive (4 prong connector that goes to the accelerometer in the woofer. I figured this is a normal 15" woofer with a 87oz magnet, but when I connected the plate amp from an 8" ht subwoofer, it came on and sounded ok, but I could hardly get the driver moving any air, before major distortion occured. I don't think the sub is special in any way, just has the extra guts inside it. I cannot seem to yield any real results with both amp's I have tried. I know the impedance of the woofer is 6 ohms on my DMM, and it just seems like I cannot get enough power to move this heavy coned beast. I think the plate amp for the yamaha 8" sub I used was about 75wpc rms. wouldn't that be enough to move a 15" woofer a bit? maybe I just need to wait for a mono-block power amp to try.... I could salvage the woofer fine and use another box, but maybe this one could work? it is a heavy built box, and sounds good until it distorts like mad.
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You should look up the specs on that plate amp you are trying to replace. I'm willing to bet that 75 watts isn't near what the original amp produced.

Did you have the sub enclosure sealed when you were testing? It's not going to work well if it isn't.

From what I saw in a review, it uses a 250 watt amp, and if it is anything like a few of Velodyne's other series amps, there will be quite a bit of headroom available, too.

I've done a bit of reading, and it is something of a tossup as to whether that sub will work well with a non-servo amp. You might get lucky, who knows, but you very well could be throwing money at something that simply isn't going to work. (and I'm thinking that the latter will be the case) I don't know how small the enclosure is for a F-1500R, as I've never seen one. The smaller the enclosure, the likelihood it will work well seems to diminish.

I'm just basing that one what I've read through a few various threads on other forums.

Infinitoid's suggestion seems to be the best route you have available. Find some specs, build a different box, different amp. Velodyne might have some useful specs available for you, contact them and ask them. They've always responded quickly to my emails.

John
 
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Regardless of the box size, if the driver isn't suffering from over excursion which it sounds like it's not, the distortion thing isn't making any sense.

Sure, the sub may not perform optimally with small amp, but it shouldn't distort unless the amp is being pushed too hard or there is something different or broken with the driver.
 
forget this thing. sorry for the time waster. I really don' think the sub will work in THIS box anymore, it needs a folded horn 15" box, and a lot of balls to push it. not a well designed unit IMO, this servo **** it just a waste of time it seems.
 
rockin1150 said:
forget this thing. sorry for the time waster. I really don' think the sub will work in THIS box anymore, it needs a folded horn 15" box, and a lot of balls to push it. not a well designed unit IMO, this servo **** it just a waste of time it seems.
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I'd venture to guess that a servo-capable driver designed for a (relatively) small box probably isn't the best match for a folded horn sub. But, I could be wrong.

Would be a shame to hack it up unnecessarily as it was a pretty decent sub, afaik.

I have plenty of amps capable of driving most any speaker, and one of the Behringer DCX2496 speaker managment systems that can dial in many types of parameters. Where you located? :smoke:
 
Seriously, though, I bought an Infinity sub with a blown plate amp for $10. I also picked up a fairly late model JVC 7.1 surround receiver with a sub pre out for $25. I run the sub out into a big Kenwood amp that I had in the closet and the speaker is wired directly to the Kenwood, bypassing the plate amp entirely. The JVC allows me to set the sub crossover frequency. You might surf CL for a receiver - used ones without HDMI are getting very cheap.
 
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