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Do it. They are awesome
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JBL 4309 Review (Speaker)
- Thread starter amirm
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Did it!
get two good subs, and actively cross them w/a quality outboard active crossover. the bass will be better, but so will the midrange, if you relieve the jbl's of having to see frequencies below +/-80hz.
i recommend trying an aiyima a07 max amp. dirt cheap, with a 48v/5a power supply. i bought two; they replaced very nice amps in my active 4-way system - a pass f2 clone and an upgraded almarro a205a mkii. both were shipped to me for <$170usd. i upgraded the op amp to a discreet op amp in the one driving the full-range driver in my oris 150 horn. (only operating from 175hz-7khz in my quad-amped system.) the sound is truly excellent. imo, of course - hah!
doug s.
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I can't imagine needing a dedicated amp to run these. And I think too many people (wrongly) assume that AVR amps suck. The act of running subs will by itself be an improvement.
that particular receiver doesn't even list 4 ohm speakers as being able to properly be driven, in its spec sheet. the jbl 4309's are rated 4 ohms, and while it's at 4 ohms mostly in the lowest frequencies, it also drops to 4 ohms at 150hz, where, even when crossed to subs, it will affect the main amp. and, while this particular receiver has preamp outs, it does not have main inputs. if it did, i'd say go ahead, run an active x-over thru the pre outs/main inputs; let the sub amps connect to the low pass side of the x-over, and feed the hi-pass side driving the monitors back to the receiver. but this receiver doesn't seem to have main inputs to try it.
one of the benefits of running subs is so your mains (and their amp) will perform better as well, not having to deal w/the lowest frequencies.
and in this case, these amps are stupid-inexpensive...
doug s.
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I mean, I have an NCore amp driving my Buchardt S400 MKII's, but those are a more power-hungry speaker than the larger JBL's. They may drop to 4 ohm—in fact many speakers do—but they're still more sensitive overall.
well, i'd recommend a used one; €1200 is a fortune compared to the aiyima and fosi 3255 amps. even used, it's a fortune. and, i'd wager the rotel sounds no better at best, and probably not as good. besides, it's likely drawing ~100w at idle, as it uses >250w to output 20w of power. the fosi/aiyima amps idle at ~6w.
save the dough on the amp, and get a pair of subs and active x-over. did you see the review on line done by the designer of cube audio and qualio speakers? he prefers the fosi and aiyima amps driving his qualio iq speakers better than a €4500 naim integrated amp...
ymmv,
doug s.
Don’t wanna bother with active crossover, why would I? The Marantzs crossover is probably fine for me. We don’t get those amps in Sweden I think and the Rotel seems like good value here compared to a lot of our offerings here. The Rotel is 130watts and the Marantz probably half that in stereo. But I want to play loud without concern of frying something due to lack of power.
i was unaware that your receiver has a built-in high-pass x-over capability. you could try it, but i'd be surprised if it's anywhere near as transparent as a good outboard x-over. it might still be decent, tho. and, i actually contacted marantz, as the x-over slope is not given in the user manual; only how to adjust x-over frequencies. is it 12db/octave? 18? 24? and no one at marantz could provide the info. i would not want to be using anything that was not at least 24db/octave x-over slope. if i were in the market for an av receiver, i'd not even consider the purchase w/o knowing this info, and/or factoring the cost of a good x-over into my buying decision. but that's just me.
regarding the aiyima a07 max, it's readily available for purchase in sweden. it is a few dollars more, than for usa customers; probably due to the vat. or maybe due to shipping costs, and vat is still added on after? i don't know. but by my calcs, you can buy a pair (get a pair and run them bridged) of the a07 max amps with 48v/5a power supplies for €154.07 shipped. if vat is added after, it's still stupid inexpensive. upgrade the op amps, for a few € more. equal or better sound quality, for quite a bit less €€€. you'd have a lot less € left over, even if you purchased a good outboard x-over.
https://www.aliexpress.us/item/1005006393104109.html
but it's your money...
doug s.
i've never heard your receiver or these speakers. but the speakers are not the most efficient speakers in the world. and your receiver is not the most powerful. however, as i understand it, you are already using the built-in x-over in the receiver to hi-pass the signal going to the jbl's. so that relieves them and the receiver's amp of some stress. the rest depends on how loud you listen, the size of the room, how far away you are from the speakers. ie: its rating at 87db/1w/1m means if you listen 4m away, it will take 32w to do 90db at that distance - which is pretty loud. but still within your receiver's rating. but it's getting close to its max - 64w needed for 93db. and marantz doesn't say what its peak power is; only rms. (i'm assuming its power rating is rms, marantz doesn't specify.)
from a speaker/amp safety perspective, if you turn it up as loud as you ever listen, and nothing is amiss, you're ok. from a sonic perspective, the sound might improve. i'd suspect it would; how much is another question.
if you're buying used, it's not as risky from a financial standpoint, as you can sell w/o taking a big loss, if it's not to your liking, and/or worth the cost to you for what may turn out to be only a small improvement. if you're going to spend a decent amount on something like the new rotel that you mentioned, if it were me, i would be wanting an extended in-home audition from a dealer before i pulled the trigger on a purchase. the aiyima amps i mentioned, however are so inexpensive that i'd not hesitate to buy them new - you could literally throw them away if you didn't care for them and not lose as much money as buying a new rotel, and then selling it if you don't think it's worth it. and, my experience w/them is they made a nice sonic improvement for me, over some high quality amps; and others have had the same experience.
after i finished writing the above, i then found amir's review of your receiver here on asr. based on that, i would highly encourage you to buy the aiyima a07 max (or a pair and run them bridged. not sure how you can hi-pass your monitors if you use the pre outs to power another amp, tho... not sure, even what the pre-outs do at all; no info in the manual. and, it seems the subs, even tho you can connect two, are mono? and after looking at the asr review, and further investigating the marantz manual; honestly, if it were me, i'd have never bought this receiver, and if i owned it, i'd be getting rid of it. no offense, but it seems like you need to get something more suited to audio, as well as being able to do h/t. whatever amp you get to use with this marantz, it will likely be running full range, w/no way to use the receiver's hi-pass function on it. and your subs are probably running mono. and if you ask marantz, you probably won't get any answers, as they probably don't know - just like they couldn't tell me what the crossover slope was.
your only other decent option, imo, if you want to keep this receiver, is buy an active outboard x-over and another amp (or two); run the marantz's pre out to the x-over, hi-pass goes to the new amp driving the jbl's; low pass goes to your powered subs - either into their lfe inputs, if they have them; or with the outboard x-over set at +/-80hz; and the powered sub's crossover set at their highest setting. based on everything i know about this receiver; from amir's measurements, and marantz's lack of useful info, an outboard amp and outboard x-over will be a worthwhile sonic improvement. or just keep what you have, w/the marantz's internal amp driving the jbl's >80hz, and the low pass output driving your subs in mono. at some point, tho, i'd imagine getting a better avr receiver would be worthwhile, and then you could still use the beter amp and outboard x-over...
re: the cheap aiyima amps, i just finished fabbing a cover for the aiyima a07 max where i installed the $30/pair discrete class-a op amps, and i'm a happy camper.
system (2nd pair of subs ~20' behind listening area):
doug s.
Another alternative which has been measured here at ASR is the Sonos AMP, I’ve had one of these a while back and my experience is inline with the measurements. It has a lot of power at 4 Ohm, should be able to drive the 4309’s plenty loud with good stability?
And no I don’t care about poor sinad on the line in since I’m not going to use that input for anything.
And no I don’t care about poor sinad on the line in since I’m not going to use that input for anything.
staticV3
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Use this calculator to calculate Peak SPL in-room:
The Sonos Amp has 210W at the knee, 250W at 1% THD+N.
The 4309 has a worst-case sensitivity of 82.5dB SPL (1W/1m).
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Well it says over 100dB, which is plenty. My concern is tho if the amp will be stable. The sentiment about these speakers seem unclear to me, some say they are heavy for the amp and some say they are quite easy to drive sooo?
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