Ring Radiator Hisssssss

[HipoFutura]

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

[scott fitlin]

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.

[Zilch]

Transistors hiss, and UHF drivers play it.

[Some better than others....]

[Baron030]

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 :)

[scott fitlin]

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.

:)

[Ken Pachkowsky]

Baron030 :)



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

Nice to see a pair...

Ken

[BMWCCA]

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.

[HipoFutura]

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

[Baron030]

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 :)

[Mr. Widget]

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

[scott fitlin]

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.

[Rudy Kleimann]

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.

[moldyoldy]

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.

[HipoFutura]

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

[Zilch]

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.

[HipoFutura]

Zilch, I don't know what diapragm was used. The rebuild cost $110. I sent it to an oufit in FL.

I just posted on DIYaudio.com, asking for opinions as to the best SS amp to drive the UHF drivers. First response was that I'm nuts to consider SS. From my experiences I've found SS amps to be much quicker an brighter than tube amps for HF. Will be interesting to see what others have to say.

I'll look into the chip amp approach. My initial reaction was negative, but I'll give it more serious consideration.


Don

[Zilch]

If Greg Timbers recommends an approach, I'd say it's worth a shot.... :p

[scott fitlin]

Crown D-75.

[hjames]

... I just posted on DIYaudio.com, asking for opinions as to the best SS amp to drive the UHF drivers. First response was that I'm nuts to consider SS. From my experiences I've found SS amps to be much quicker and brighter than tube amps for HF. Will be interesting to see what others have to say.
Don

Crown D-75.
So If I was to biAmp or triAamp my 4320s, I gather I could take my existing "Giskard-style" crossovers and just put them at the output of my preamp, then feed their output to discreet amps for each driver? :D

So the D75 (est 40w/ch) would be a good approach to feed the slots?
What about the 2420 Horns - should I find a D-150
What about the 2215s - something like a DC-300?

I'm just feeding the whole thing currently with a 110/ch JVC high end A/V receiver now, but I believe I can pull the front channel preamp outs to feed external gear.

[Mr. Widget]

So If I was to biAmp or triAamp my 4320s, I gather I could take my existing "Giskard-style" crossovers and just put them at the output of my preamp, then feed their output to discreet amps for each driver?:shock: :spchless: :shock:


No! You would need an active or passive line level network that is designed to go between your preamp and your various amps. If you are even remotely considering this you should read up on multi-amping.


Widget

[scott fitlin]

So If I was to biAmp or triAamp my 4320s, I gather I could take my existing "Giskard-style" crossovers and just put them at the output of my preamp, then feed their output to discreet amps for each driver? :D

So the D75 (est 40w/ch) would be a good approach to feed the slots?
What about the 2420 Horns - should I find a D-150
What about the 2215s - something like a DC-300?

I'm just feeding the whole thing currently with a 110/ch JVC high end A/V receiver now, but I believe I can pull the front channel preamp outs to feed external gear.Yep, that combination in that order will work.



As Widget stated, you really need a dedicated active electronic crossover.

There is a good place for GOOD electronic crossovers, available in kit form, reasonable prices, to very expensive prices. I recommend an XM-44, youll have to decide your crossover points, and is available with 6,12,18,24 or 48 db slopes.

www.marchandelec.com (http://www.marchandelec.com).

[Rudy Kleimann]

I second that recommendation on the Marchand kits. Was thinking of the same, but had a case of 'sometimers' with names while posting Saturday.

Of course, he could buy a Rane or Ashly used. Just make sure it's a recent design 24dB/octave Ashly and not one of the old ones, which in my experience didn't sound too good. Both brands sound great, and customer support is very good. The Ranes are more plentiful and less expensive, and I like the delay (driver alignment) function and CD EQ capability of the Rane models. never had a use for the adjustable filter action of the Ashlys -usually were just another knob to find mysteriously tampered with. My neighbor and I both use Ranes in our Audiophile systems with no disappointments in their sound quality.

Same for the little Crowns. I've used one of a pair of Crown Power Line Two amps for years to drive my HT surrounds, and though they're a little more powerful than a D-75, they wouldn't actually be overkill for the UHF as long as something crazy doesn't happen. I'll probably be using another one for my triamp project next year, pushing 2405's or similar. Use what you got... Truth is, he probably could do with 20 watts RMS if he has a smaller amp laying around. Try it out and see how it sounds.

[HipoFutura]

Well, for chuckles I just ordered a pair of Velleman 7 watt chip amps and power supplies. This will be a bit of fun and I can throw the whole mess away and only be out $53. I'll put an amp, PS, and big heatsink in each of the cabinets I made for the UHF drivers. I was unhappy with the cabinets, but am now glad to have the extra room. The downside to this is having to run power to each of the UHF cabinets and I'll have to run interconnects to them; can't us speaker wire. I'll use balanced lines with XLR connectors. That will cost more than the amps!

If this doesn't work out (sound good) I'll build or buy a real two channel amp in the 40 WPC range and be done with it.

I've decided the DBX 234XL has to go! I'll look into Marchand, Ashly, Rane, and DIY crossovers. I like the 80 hz and 10K hz crossover points I'm currently using. This seems to leverage the best aspect of all my speakers. The setup really sounds phenomenal. The tri-amp configuration makes the little L100s sound like a concert hall.

Don

[Rudy Kleimann]

JBL offers two diaphragms for their ring radiators: a D8R075 and a D16R2405. both fit all of the old ring radiators. After much research into this, I can confidently tell you that the differences are ONLY in frequency response and ruggedness, due to a thicker diaphragm on the D8R075. The 075 diaphragm can be used as low as 3KHz, but response falls off above 12-15K. The D16R2405 is used only above 5-7KHz depending on who you ask and what JBL not you read, but its frequency response smoother and goes much higher than the D8R075. Both use the same voice coil. One may sound a little louder than the other too, depending on the frequency range it is used in. This may explain why your newly repaired unit sounds louder than the other ones you have. JBL has used the D8R075 in some models that used the "baby cheek" 2404H UHF driver, noted by the model number of 2404H-1, for more ruggedness and more output in the 3-6KHz range.

Although most people agree the ring radiators (those equipped with the D16R2405 diaphragm) sound best above 7-8KHz, I do question your choice of 10KHz as a crossover point, especially in an L100/4311. That 5" cone mid is long gone by 10KHz; factory crossover frequency is 6KHz. I seriously doubt the mid has very good output at 10KHz, and if it does, it will certainly be dispered over a very narrow angle due to the large cone area and the short wavelength at 10KHz.

Also, note that the ring radiator is actually a 12-ohm impedance, no matter what the driver nameplate says (8 or 16 ohms) or which JBL diaphragm is used. This means that if the L100/4311's passive crossover is used and was designed for an 8-ohm tweeter, the 12-ohm ring radiator will actually be coming in at 4KHz, meaning there will be a broad overlap in output between it and the mid between 4KHz and 6 KHz. Of course, active crossover and bi/triamp solves that...

[HipoFutura]

Rudy, great info on the diaphragm. I'm going to check with the outfit who did the rebuild and see what they used.

I'm running a tri-amp configuration. The crossover points are 80 hz and 10K hz. The L100 has an easy time with the mid-range. The LE26 in the L100 hands off to the ring radiator at 10K hz.

Don

[Rudy Kleimann]

Let me get this straight:

You are using the L100's from 80Hz to 10KHz through the 234 x-over mid output to an amplifier , with a subwoofer running from 80Hz down on its' own amp, and the ring radiator running from 10KHz up on another amp?

[Rudy Kleimann]

What ring radiator model are you using? 075/2402 "bullet", 2404H "baby butt", or 077/3405H "slot"? Seems like you said you have more than one version in your collection...

[HipoFutura]

Yup. I have a Phase Linear 400 driving the two subs. A pair of Curcio tube mono-blocks for the L100s, and another Phase Linear 400 for the ring radiators. I'm presently building a 220 WPC SS amp to replace the PL400 on the subs. As well, I'm now looking to replace the PL400 on the ring radiators.

I have a pair of 2402H (one is the fresh rebuild) and a pair of of 2405.

Don

[Rudy Kleimann]

Check your PM's Hipo...

[scott fitlin]

If you have em, the Crown Power Line two is even better than the D-75. But, this wasnt a very common amp, it was crowns attempt to get into the Consumer High End during the 80,s but wasnt wildly succesful, as they are in the pro markets.

Multi-Mode circuitry offers a very clean, sweet top end, and I have and use these too.

[HipoFutura]

Well, I've made some progress with the ring radiators. I bought off ebay a Crown D-75 and am waiting for it to arrive. As well I bought all the required pieces to build two Velleman K4001 chip amps and two K1823 power supplies. Everything cost about $110. I'm using large 25V transformers and substantial heatsinks. They work great and have all the power required. The power supplies are stable and way over powered for the little amps. I build two back panels for the cabinets. One set has the standard speaker wire terminal block and the second set has the chip amps, power suppies, AC cord, and RCA connector. This way I can switch between the two configurations (internal amp or un-powered) by simply swapping the back panel on the cabinet.

The only problem is that I have to run AC and interconnect cables to each enclosure. This could be 15' - 20' from the amps, preamp, and crossover depending where I ultimately place my stereo system.

If I build another set of ring radiator enclosures I may sell this set with the walnut veneer cabinets, chip amps, and 2402H radiators. They really do look sharp and sound fantastic.

[Zilch]

The only problem is that I have to run AC and interconnect cables to each enclosure. This could be 15' - 20' from the amps, preamp, and crossover depending where I ultimately place my stereo system.I don't get why you don't just build a cab for the chipamps and their power supplies into your rack and run the output high-level speaker wires only, instead....

[HipoFutura]

I don't get why you don't just build a cab for the chipamps and their power supplies into your rack and run the output high-level speaker wires only, instead....

Zilch, that is waaay to logical! Actually, I will probably put them into a box so I can have a small amp to experiment with. I'm curious to see what type of fidelity they have across the entire audio spectrum. I do like the idea of a pair of self contained UHF enclosures, but it make no practical sense.

Thank you again for all the help!

Don

[Thom]

it used to be common knowlege, or an urban myth, or perhaps it was an urban myth that it was common knowlege. That 075's were used as ultra sonic devices in traffic lights. Don't know where I first heard that but I've heard it many times. Doesn't make it true. I'm not sure if I ever saw it in print but made up or real I didn't make it up.

[louped garouv]

it used to be common knowlege, or an urban myth, or perhaps it was an urban myth that it was common knowlege. That 075's were used as ultra sonic devices in traffic lights. Don't know where I first heard that but I've heard it many times. Doesn't make it true. I'm not sure if I ever saw it in print but made up or real I didn't make it up.

http://www.audioheritage.org/vbulletin/showthread.php?t=12208