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Thread: Ring Radiator Hisssssss

  1. #1
    Senior Member HipoFutura's Avatar
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    Ring Radiator Hisssssss

    Being new to ring radiators, I don't know if this is normal or not. I have two pairs of radiators (2402H and 2405). all four of them emit a hiss. It isn't offensive and it doesn't increase with gain. I've tried them on different amps with a DBX234 crossover and connected them to the HF crossover on an L100. In all cases all radiators hiss. One is just returned from a JBL authorized repair shop having had a new diapragm installed.

    I've noticed they hiss more when connected directly to a Phase Linear 400 that is tri-amped. They hiss less when connected to the HF on my L100.

    Is this just the way life is with ring radiators or do I have something else going on?

    Don

  2. #2
    RIP 2010 scott fitlin's Avatar
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    This is normal. Your hearing the noise and gain of your amp, preamp, etc. With very high efficiency devices, you will hear any noise from your components.

    But, you hear less hiss when connect the tweeter to the HF section of the L100,s crossover, because the HF is padded down in the xover.
    scottyj

  3. #3
    RIP 2011 Zilch's Avatar
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    Transistors hiss, and UHF drivers play it.

    [Some better than others....]

  4. #4
    Senior Member Baron030's Avatar
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    I've noticed they hiss more when connected directly to a Phase Linear 400 that is tri-amped. They hiss less when connected to the HF on my L100.
    Is this just the way life is with ring radiators or do I have something else going on?
    Don

    Oh my God! Connecting a ring radiator directly to a Phase Linear 400!
    I hope you have some kind of a high pass filter wired between that amplifier and the drivers. Otherwise, those drivers are toast.


    The 2402 and 2405 drivers are only rated 40 watts. So, you don't need that much power. I have been driving a pair of 2405s with a crown D-75A. And I have to turn it up some insanely loud volume levels just to get the green "signal presence indicators" to light. So, a Phase Linear 400 is just over kill.

    Look in to using a smaller amplifier to drive the ring radiators and the hiss problem will go away.

    Baron030


  5. #5
    RIP 2010 scott fitlin's Avatar
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    Hes right! A Phase Linear 400 is WAYYYY too big of an amp for the JBL 2405.

    I run 16 JBl 2402,s in my place, and all I use is 2 Crown D-75,s for them, 4 tweeters per channel of each amp, and I have highs a plenty.

    1 watt will make them go, and go plenty far at that!

    Not only that, but JBL slots and bullets and crown D-75,s are a match made in audio heaven, great synergy between them! It works really, really well.

    scottyj

  6. #6
    RIP 2014 Ken Pachkowsky's Avatar
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    Quote Originally Posted by Baron030

    Baron030

    My second pair of JBL's were a pair of 030's.

    Nice to see a pair...

    Ken

  7. #7
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Ken Pachkowsky
    My second pair of JBL's were a pair of 030's.

    Nice to see a pair...

    Ken
    Still the speakers in my main listening room. One side (before stereo) has been in my home since new and when I was in diapers. It may be all in what your ears get used to but they sound delightful to me! A standard by which I've judged everything else ever since.

    To the point; if, and only if, I isolate the 075 with a cardboard tube direct to my ear, I hear a slight bit of hiss, depending on the sound source (tape is obviously worse, but then I'm only running them on a D150A-II. No telling what's going on above the limits of my ears! The 075 will produce whatever sound it's fed.

  8. #8
    Senior Member HipoFutura's Avatar
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    So, let me see if I understand this. Ring radiators hiss when hooked to a SS amp, and you think 200 WPC a bit much for a 2402H. Isn't wattage like horsepower? If a little is good, then a whole lot more is even better!

    Just hacking on you guys! I'm in the process of reconfiguring my amps. I have the Curcio tube mono-blocks for the L100s. I'm presently building a 220WPC @ 8 ohms to drive the pair of subs. Once completed I'll build a low watt SS amp for the ring radiators. Haven't picked a design for that amp. It will be something appropriate. I'm using the PL400 because that's what I have on hand.

    I love the Phase Linear amps and will continue to use the PL 4000 Series II preamp. It's a very nice piece! However, by building new poweramps I can take advantage of all the advances in SS technology over the last thirty years.

    Thank you for all the advice and guidance!

    Don

  9. #9
    Senior Member Baron030's Avatar
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    Hi Don
    I have another idea. Maybe, the hissing sound is coming from the electronic crossover network. So, it would not matter, which amplifier you are using, the hiss would still be there. Amplifiers like computers follow the same general rule: "Garbage in = garbage out"

    Quoting from my Ashly operating manual:
    In a typical setup, power amplifier input level controls should be run "full-on", with the level control being accomplished at the crossover.
    I found that in my case, Ashly's advice to be wrong! I got a much quieter operation by leaving all of the gain controls very near "unity gain" and then adjusting the input levels on crown amplifiers to balance the system. Also, I found that running balanced audio cables between the crossover and the amplifiers helps a lot.

    Try experimenting with the gain controls, to see if that makes any difference in you system.

    Baron030

  10. #10
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Baron030
    I found that in my case, Ashly's advice to be wrong! I got a much quieter operation by leaving all of the gain controls very near "unity gain" and then adjusting the input levels on crown amplifiers to balance the system. Also, I found that running balanced audio cables between the crossover and the amplifiers helps a lot.
    It is considered best practice to never pad down the input of your amps... the amps will not offer their absolute best sound quality or dynamics if padded down... however if you have a noisy amp that is connected to a very sensitive driver you may prefer the amp padded down. You might also try padding the speaker directly. The best solution is to use a quiet amp.

    If your active crossover is too noisy, it should be replaced. Using balanced cables will only reduce hiss due to the fact that driving a balanced amp you need to double your previous stage's output voltage to reach the same volume... this will effectively pad down the front end of your amp. Simply running balanced cables won't have any effect.


    Widget

  11. #11
    RIP 2010 scott fitlin's Avatar
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    I`ve done it both ways, using the amps input level attenuators, and running the amp wide open, and using the output level attenuators on the crossover.

    IT ALWAYS sounds better to me running the amp wide open and using the xover as level control to balance out.

    I also believe in running a gain structure in multi amped systems according to amp power, amps input sensitivity, for the various ranges. For instance, the Crown D-75 has an input sensitivity of 1v, or .75v if you want it that fast, and this is good for uHf, as the amps input can respond to the relatively small signal content up this high, conversely, the bigger amps like a Crown DC-300A have an input sensitivity of 1.75v and you wind up having to push the highs to hard to drive the amp satisfactorily, but works out good for bass and midbass ranges.
    scottyj

  12. #12
    Senior Member Rudy Kleimann's Avatar
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    small amp, direct to 240x

    Widget has written an Excellent thread titled "Ring Radiator Comparisons" that you really should read. Lots of good stuff here, thanks to his efforts, great test equipment, and contributions from other forum members that live near him.

    It's fairly well known that the ring radiators need very small amplifiers due to their extremely high efficiency and the limited amount of UHF signals in music. 40 watts (re:8ohms) would produce 125dB at 1 meter on 2402's. A cymbal crash at this level could do some damage! How big is your listening room?

    The ring radiators sound much better when directly connected to the amplifier with no crossover components or L-Pad in the circuit between amp and driver, so your triamp approach takes care of that. It's been suggested that the ring radiators are ideal candidates to be powered by little "chip" amplifier kits. The actual impedance of ring radiators are really about 12 ohms, so a high-current power supply is unnecessary, which keeps costs down. Large heat sinks would not be a requirement either, due to the brief transient nature of UHF signals. You could even build it inside the cabinet using a metal plate as a combination input panel-heatsink- base plate for the amp circuitry and PS. This would also improve damping and transient response since the cables to the tweeter would be so short.

    One forum member here used 2404 "Baby Cheeks" horn loaded ring radiators from 8-10KHz on up to fill in where his big HF horns' response fell off and got ugly sounding. He reported that, at the recommendation of a JBL PRO Rep, he bought the appropriate capacitor to make a passive crossover that attenuated everything below 20 KHz at 6dB per octave and placed it in series with one of the leads going to the 2404. He said it accounted for the falling response of the 2404 above 12KHz, and that, due to the extremely high output of the 2404 ring radiator, they were still plenty loud enough to keep up with the big horn system. If your are triamping, installing or engaging CD horn EQ in the Active crossover on the UHF signal output would accomplish the same thing while still allowing direct coupling of the amplifier to the ring radiator.
    The noise issue could be your DBX crossover, or maybe the gain structure in your system (signal levels from one component to the next from signal source through preamp to crossover to amp) could be out of whack. Balanced lines increase signal to noise ratio by 6dB and are immune to interference and noise problems along the cable, so use balanced cables between components wherever your equipment will accept it.

    I don't think much of the DBX 223 or 234 crossovers. To me, they aren't super-quiet, and the signal degradation from input to output left me disappointed. Several bands I mix for have them in their PA's, and a few sound companies I have worked for use them, and I owned a couple of them for a short time. They work fine, but they just didn't cut it at home. AfterA/B'ing them against others at home and on the road, I never looked at them the same again...

    The Rane active crossovers sound a helluva lot cleaner and quieter, and can be had cheap on the used ebay market. The delay/alignment feature is useful for time-aligning HF horns with MF cones, and they have provision inside for easy addition of CD horn EQ if you're the least bit handy with a solder iron. You can even transplant the time delay circuit from one output section (Low, mid,high) to another if need be, i.e. horn-loaded subs, or to delay the ring radiator to time-align it with the HF horn below it. The mod info is all on the Rane website, and easy to perform.

    Ashly crossovers sound slightly better yet (I have limited experience with these), and have a couple other tricks up their sleeve that are useful in some cases, but they are much less plentiful and command a much higher price on the used market. I have half a dozen of the Ranes and am very pleased with them both in PA use and in my high-end home setup.
    Last edited by Rudy Kleimann; 09-02-2006 at 02:38 PM. Reason: added information to original post.

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    Hiss, or thermal noise, is always present with electron flow, and is a wideband, constant-energy component, so, like white noise, it becomes more apparrent at the high frequencies your ring radiator handles. If you can only hear it with system levels at normal listening level and no input by putting your ear within a foot or two of the speaker, it can be considered to be normal. If, however, you can hear it from your normal listening position, it becomes worth trying to reduce it. It could be a single, perhaps defective component, or a cumulative effect of noise from several components. The first step to reduction is to locate the source(s).

    Turn off and disconnect all system signal wiring except the connection from speakers to amp. Power the amp, set the gain to normal levels, and see if the hiss remains at the earlier level, is reduced, or is inaudible. Continue reconnection and testing one component at a time, back-to-front in the same manner, and you'll learn if the hiss is cumulative or isolated to one device. If from a single device, it could either be defective, poorly designed, or simply in need of closer attention to its' I/O sensitivity or impedance in relation to the devices it is connected to. Cumulative thermal noise is harder to deal with, and can only be reduced by careful setup of system gain and interconnection, reduction in the number of components used, or a complete startover with a new (and quieter) system.

    Even in systems that exhibit seemingly normal thermal noise characteristics, it's a good idea to try to reduce any noise, as it effects S/NR, and ultimately reduces the system dynamic range. Getting the system gain structure setup correctly is a good place to start, but to do it, you have to thoroughly understand the hows and whys, some of which has been described here already. I've seen more than one instance where the recommendations in this regard by equipment manufacturers are simply wrong, as explanation of the best methods is usually beyond the grasp of the typical plug-n-play user. Each device in the chain should be set to output its' maximum undistorted level when provided the highest input level it can tolerate. Sometimes, this means max setting, but usually not. Increasing gain settings beyond this point will only result in distortion, increased noise levels, or both.

  14. #14
    Senior Member HipoFutura's Avatar
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    I've noticed that the one 2402H that was just rebuilt has considerably more hiss than all the others. The other 2402H and the pair of 2405 all hiss about the same. Once the music begins they all sound about the same. Very difficult to hear a difference in the music.

    When I have more time I'll experiment with the amps/preamps/crossover and try to locate the source of the hiss.

    Rudy, I have to agree with you on the DBX234XL. It is very disappointing! I find the low-freq crossover to be terrible! My subs sound awful. I was using a Paradigm X-30 crossover before I went with the tri-amp configuration. It was clean and the LF was fantastic. I now find it muddy with the DBX crossover. I can't tolerate it and will have to make a change soon. I'm going to look for a used ashley. The DBX 234 has lots of features, but just doesn't sound good.

    What size amp would be suitable to drive the ring radiators? Is 40W RMS appropriate or still too big? I'll build a two channel SS amp. The chip amp idea is interesting, but I don't want to have the amps scattered with the speakers and require running power to the cabinets. I'll build something that can be stacked with my other grear.

    Don

  15. #15
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by HipoFutura
    I've noticed that the one 2402H that was just rebuilt has considerably more hiss than all the others.
    Do you know for certain what diaphragm went into it?

    Also, consider repackaging inexpensive ($30) chip amps from Parts Express with a decent power supply. You don't need more than one or two good watts output, is all.

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