Passive subwoofer amps help!
I acquired two massive subwoofers (over 230lbs each) that were mated to a $100k+ custom system and I need to power them somehow. In my limited research, I'm a bit confused about all this. I'm used to my subs being powered. The subwoofer amps I've found by Dayton Audio seem to be very lower powered. Can I just buy an SVS PB16 amps off ebay and build a box and use that? That gives plenty of subwoofer power and the ability to control with phone. Or is that a big sin in the subwoofer world? Why are there not more external high powered solutions for this with a volume knob, low pass knob, and phase switch on the front.
I did look at the Klipsch RSA-500 but it specifically lists the subs this amp is to be used with. Also, for $1k+, it's not that powerful.
Ok those Crown amps are only amps though, what about volume control, crossover, and phase control? I suppose I'd have to use the controls within the Anthem preamp section to control volume, xover, and phase? That's fine, but it's just very limited on the volume as it only goes up/down 10db or so. I would think i'd need a gain knob at least no? I'm really surprised there isn't some kind of awesome external subwoofer amp that gives you flexibility and options kinda like most plate amps on subs with multiple inputs/outputs and controls. |
@dtximages Wrote:
Crown amps have gain knobs on the front panel! Mike |
These were some subwoofers designed and made by Destination Audio to be paired with horns on top. All together, the speakers were in the $50k range. They were a one-time build and apparently tuned down to 20hz. If you look up the Destination Audio Nika speaker, the bass section is identical to that except without the horn tweeter built in. |
I just ran across a Behringer NX6000 locally I can grab for $400. Doesn't have DSP but my Anthem has all that. I think I'll try this and see what happens. FYI, the subs do already have dayton audio SPA250DSP amps built in but they're literally built into the cabinet. The builder drilled holes in the side with a usb, power, and RCA jack. Strange way to do it, but the cabinet is curved and the owner comes to your house to calibrate. All calibration is meant to be done through the usb connected to a computer. |
If you want higher performance you will need a two way crossover such as a MiniDSP or a preamp with digital bass management. I do not like Crown amps. I have had them twice and both times they were unsatisfactory. I use QSC PL380s which are killer subwoofer amps, but on the pricey side. The GX5 will be fine and it has a built in subwoofer low pass filter. DO NOT use the RMX series amps. They have a habit of self destructing. I personally destroyed 3 RMX 5050s, fortunately under warranty. Finally, QSC insisted I switch to PL380s, a more expensive amp by $1000 each and they did not charge me the difference! They are the best subwoofer amps I have ever used. QSC gets an A+ for service. |
@mijostyn , thanks for the QSC suggestion. I should have mentioned that the Dayton SA-1000 has a fixed 80 Hz second-order line level highpass filter to roll off the bottom end going to the amp for the main speakers. No DSP in the Dayton; it's all analogue. Reliability has been very high in my experience; aside from a brief string of defective units that were either DOA or died within the first couple of weeks, I've only had ONE unit (out of about 200) fail in the field. It failed about 4 years and 10 months into the 5 year warranty, and Parts Express replaced it under warranty. Duke
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@audiokinesis I use Dayton Reference subwoofer drivers and I get them from Parts Express. I have not seen anything that is functionally superior at any price. They make sub drivers suitable for any enclosure situation. I do not like putting electronics inside subwoofers. It is not a great environment for electronics. Forgetting about the pounding they take, heat is a problem in small sealed enclosures. Pushed loud for extended periods sub drivers get hot producing an oven environment. How hot I can not say, but I dissected an old driver that I used for 20 years and the voice coil was black! |
Subwoofer bass myths, see here!Mike |
@mijostyn , I agree with you about the heat issue. Except for the very first generation of my subwoofer system, dating back to 2006, I haven't been putting amps inside of subwoofers. My observation (based largely on conversations with customers) is that high-power compact equalized sealed-box subs tend to have fairly high failure rates for their amplifiers and their woofers, and I think it goes back to the "oven environment" you described. One of the reasons I use vented enclosures (tuned such that their response is the approximate inverse of typical room gain from boundary reinforcement) has to do with thermal power handling. A comparable sealed-box sub will theoretically need roughly three or four times as much power in the region of the port tuning frequency in order to have the same frequency response. Also, a port allows an exchange of air with the outside world, so you don't get that "oven environment" that you do with a high power sealed box sub. In other words, imo there are arguably worthwhile thermal benefits from making a vented box approximate the frequency response of a very low-Q sealed box down to the port tuning frequency. In my opinion. Duke |
@mijostyn wrote:
I’ve previously used Crown’s Macro Tech class A/B series for subs duties for a short while, and found them to be very good amps (not only in the subs region, certainly with the 3600 model on down), but their built-in fans were noisy like angle grinders, and by now the Macro Tech’s also have quite a few years under their belt. The class H-based Crown K2 is another very good and popular subs amp, and moreover it’s passively cooled (but one needs to disable the auto standby function). I used the K2 over my subs for some years, as well as upper bass/lower mids duties, and it excels in the bottom octave in particular with good weight and control while lacking a bit of mid bass prowess. A beast of a subs amp is the class TD-based Lab.gruppen FP6400, which I used for years with my subs as well as midbass section. Crazy powerful amp, though not as musically natural in the lower octaves compared to my current MC² Audio class A/B amps; finding a suitable subs amp isn’t only about having enough power (which is the easy part), but also and not least about what complements the audio range above the subs region. I find using essentially similar amps top to bottom to be very important for overall coherency and tonal imprinting - something few seem to be aware of and actually implement in their subs setup and considerations. Using a dedicated quality DSP (that acts as a digital XO for the mains as well) with a vast and intricate range of settings only adds to the advantages. @audiokinesis wrote:
+1 Like ported boxes, tapped horns (contrary to sealed designs) also have excursion minima at the tune, but by comparison seem to be less marred by group delay effects. Being also they’re very efficient, certainly with a tune not much lower than 20-25Hz - in addition to having the driver’s backside exposed in free air at the mouth - makes them very resilient to thermal overheating. @ditusa wrote:
+1 |
@phusis Funny you should mention the K2. They were the last Crown amps I will ever own. Their control over big sub drivers with high BL products was terrible. I think it was the back EMF that destroyed one of mine, the other went in the dumpster. @audiokinesis Your's is a reasonable argument. I have several problems with vented designs. The first is their low bass falls off sharply under the resonance frequency. With very low notes (organs) at high volumes you can hear the port. Enclosure sizes are generally larger. A 15" vented design is huge, worse if you use 4 subwoofers. My approach takes the same path as my RAM TRX. You use a huge motor and a ton of power (2500 watts per sub) in small sealed enclosure along with room control, digital crossovers and digital EQ to make the driver do what you want. So, you burn up a voice coil once in a while. I keep two drivers in reserve although I have yet to lose a dual voice coil Dayton yet, it is only a matter of time. Subwoofer drivers take a beating as it is leading to a high failure rate in any event.
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@phusis Good article and no arguments from me. I cringe every time someone characterizes a subwoofer driver as being "fast" I do not care so much about efficiency. I care most about accuracy and by a huge margin it is the enclosure that causes the most trouble, not the driver. The majority of enclosures are musical instruments. |
@mijostyn wrote:
My context of experience with the K2 is having heard it driving different high efficiency, large subs (a pair of them in all cases) fitted with woofers with a BL factor in the 20-26Tm range, and no control issues here. Honestly I’ve never heard the K2 at the end of its ropes here either, nor the subs for that matter - even at bonkers SPL’s. Your context of previous use with the K2's is obviously quite different, and to put things into perspective: using sealed subs with over 10dB’s lower sensitivity there’s a power requirement over 10 times as much, meaning - in theory - a 500/800W K2 would do with high eff. subs that a some 10kW amp should do with a low eff. subs equivalent. That is: the first scenario offers you both headroom and prodigious pressurization in a domestic environment; the latter would end up in smoke trying to achieve anything similar.
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I’m assuming the latter quote of yours is aimed at poster @ditusa, but I’ll have a go at it nonetheless. From the above it follows that the driver is a potential issue of yours. Needing a couple of them in reserve due to expected woofer failure - that is, woofers used here that are by all accounts no slouches in themselves - is indicative of very high power output and occasionally using the subs close to or even beyond their capabilities, which again equates into steeply rising distortion levels. You may have won points with close to inert sealed subs cabs, but from my chair the drivers will bring that score into the negative again if working very hard. I’m assuming though you have a winning combination at more "normal" listening levels. @ditusa wrote:
+1 The Studio Ref. 1 and 2 are great sounding amps indeed. I almost bought the Ref. 2 some years ago, but have heard them regularly at friends’ places over the years. Rock solid, reliable amps, and it takes some heavy beating to spin up those fans. I never get to that (i.e.: spinning up the fans from their close to idle state) with my MC² Audio amps and efficient speakers, only the occasional flashing of the blue signal LED’s on the midbass and subs amps when watching movies, in which case it means they are using +10W. |