Bi-Amp 4430 Results

[RichK]

Well I gave it a whirl, and it just didn't float my boat. Seem to lose a lot of detail and imaging. I used the 5235.

Rich

[grumpy]

You might try swapping the polarity on only one of the amps HF -or- LF
(both speaker leads +/-) before giving up on this. I seem to recall this
having an effect with mine, using the 4430/4435 cards in a 5235. It was
a long time back (for me to remember clearly), but simple enough to try.

I -do- clearly recall that setting the levels on the 5235 was very critical,
and that the normal/bi-amp switch was a bit fussy (could use a bit of
cleaning and lubrication... or outright replacement).

[Mr. Widget]

Well I gave it a whirl, and it just didn't float my boat. Seem to lose a lot of detail and imaging. I used the 5235.Perhaps a better crossover would help, but as I have said before... to get a "real" improvement from a multi-amped system... you have to do a lot of things right.


Widget

[timc]

Which amps did you use? Where they similar? thinking of sensitivity and gain.

A difference of only >0.5dB will make everything go bad.

[cosmos]

Personally, I have never heard a passive system not be surpassed by a active one. I'd suspect something was wrong in your setup.

[RichK]

I used a couple of Marantz 250M's.

I didn't play with the settings much at all because I don't know how to attack that. Is there a way to go thru a set up. All I seemed to hear was the speaker getting more power.

Rich

[grumpy]

Do you have the 5235 manual? Also it is not trivial to do by ear (without
test equipment). I assume you have the proper 5235 cards for this system
and that you've noticed that the output connector pin-out of the 5235 is
non-standard.

I'm in no way challenging that you may very well have a preference for the
non-biamped system, or that higher quality electronic crossovers could
further improve the sound of a properly biamped 4430, ... it was just not
my experience that biamping 4430's with a 5235 resulted in drastically
less enjoyable speakers (it was just a hassle turning all of that junk on
and off).

(I should also mention that I was feeding the 5235 input from a balanced-out
preamp).

[Krunchy]

Something may need to be tweaked, the sound should definitely improve if you are biamp-ing, by how much?
thats more objective.
Crossover will play a major role in what you hear.
Keep on working!


(it was just a hassle turning all of that junk on and off).

:D

[Mr. Widget]

S...the sound should definitely improve if you are biamp-ing, by how much?
thats more objective. I don't agree with that blanket statment.

About the only blanket statement I can think of at the moment that would be true, is "the system will be quietest with the power disconnected." ;)

How about this: "The system should improve if you are bi-amping it correctly."


Widget

[RichK]

Do you have the 5235 manual? Also it is not trivial to do by ear (without
test equipment). I assume you have the proper 5235 cards for this system
and that you've noticed that the output connector pin-out of the 5235 is
non-standard.

I'm in no way challenging that you may very well have a preference for the
non-biamped system, or that higher quality electronic crossovers could
further improve the sound of a properly biamped 4430, ... it was just not
my experience that biamping 4430's with a 5235 resulted in drastically
less enjoyable speakers (it was just a hassle turning all of that junk on
and off).

(I should also mention that I was feeding the 5235 input from a balanced-out
preamp).


I do have the manual, but it's pretty simple. I do have one of those cheap Radio Shack SPL meters. But as far as having a pole, microphone, and a nice HP/Agilent Spectrum Analyzer....I'm out.

I wonder if my crossovers are tired.

Rich

[Mr. Widget]

I do have the manual, but it's pretty simple. I do have one of those cheap Radio Shack SPL meters. But as far as having a pole, microphone, and a nice HP/Agilent Spectrum Analyzer....I'm out.

I wonder if my crossovers are tired.If you place the SPL meter on a stool or rig some sort of repeatable stand, set it up 4 feet away from the speaker on axis with the horn, play pink noise through the system (one channel at a time) and set it so that it is say 75dB with only the horn playing, then disconnect that amp and run the woofers and dial it in until you get the same reading... repeat on the other channel and you should be really pretty close.


Widget

[Krunchy]

I don't agree with that blanket statment.

About the only blanket statement I can think of at the moment that would be true, is "the system will be quietest with the power disconnected." ;) :D

How about this: "The system should improve if you are bi-amping it correctly." Widget

Yes, thats more to the point, the key word there being correctly. From my own experience I definitely noticed a much "livelier" sound when I bi-amped them, by how much did it improve is hard to hard for me to put into words, but it was certainly noticeable. If I had the extra gear I would have keept the bi-amp configuration but they are now in passive mode and sound fine to me and I'm happy with them.

RichK keep working on it and try out Mr. Widgets advice with the pink noise spl meter since you have it. Let us know how you make out.

[grumpy]

If you place the SPL meter on a stool...... you now have a pair of stools. ;)

Seriously, I'd have to choose a curve for the specific-brand SPL meter and run
a comparison test vs. a swept sine plot before I'd step out on that limb.

IIRC, the unity gain setting on the 5235 was "8" and was difficult to set
within a 1/2dB... something I'd rather not depend on a pink noise source
to accomplish... but better than nothing I suppose.

A $50 mic (or the SPL
meter voltage output) and some free software would likely produce both a
better answer if done correctly, and initiate a barrage of problems and
questions in the process of getting there ... so, ah, nevermind, an RS SPL
meter -is- a handy tool to have, and is a smidgen better than just guessing.

[Mr. Widget]

Seriously, I'd have to choose a curve for the specific-brand SPL meter and run
a comparison test vs. a swept sine plot before I'd step out on that limb.I've actually done it with a Rat Shack meter... it does work. :)

In the mid band, where most of the energy is in a test like this, they are remarkably accurate. At 1KHz, my Rat Shack meter is within 1dB of my calibrated CLIO rig.

Now, I personally wouldn't use a Rat Shack SPL meter to set an EQ, but many have while using a chart to "calibrate" their meter.


Widget

[grumpy]

Good to go then :)

[SMKSoundPro]

Dumb question: Does the 5235 xover have internal dip switches like the 5234a? And if so, are there some previous dip switch settings interferring with what you hear? Or is the 5235 straight out of the box, new, and uncluttered with someone else's project?

I am just asking.

Scotty.

[RichK]

Dumb question: Does the 5235 xover have internal dip switches like the 5234a? And if so, are there some previous dip switch settings interferring with what you hear? Or is the 5235 straight out of the box, new, and uncluttered with someone else's project?

I am just asking.

Scotty.


I checked the switches again and they are in fact set in the default position.

Rich

[SMKSoundPro]

okay. Thanks for answering my dumb questions.

Link: http://www.audioheritage.org/html/profiles/jbl/4430-35.htm

I just read this article and am now more informed of the design and compromises made during the initial 4430 project. A very interesting read!

There is SO much information here. I am so grateful that all of it is so easily found.

Good luck with your project.

Scotty.

[robertbartsch]

In the early 1970s, I had a pair of VOTTs and the Altec sales literature of the period was very keen on bi-amping these systems. I think Altec was venturing into solid state power amps at the time, so maybe this was a marketing push by them to sell lots of Altec power amps.

I suspect bi-amping was done a fair amount w/ A7s in movie theaters and SR but that is only a guess. One obvious factor at the time was that amps were very small by today's standards. The Crown DC-300 was considered an absolute "huge monster amp" at that time.

Anyway, I always wanted to try bi-amping and I even purchased a pre-owned Harman (dbx??) electric crossover that is still sitting in my basement.

If I were to tackle this one, I think I would want both amps to have gain controls and be manufactured by the same company. I would also avoid a three way system with a passive Xover to control the mid and HF drivers - too much in the system to go wrong.

....Good luck with the experiment.

[jblbgw_man]

I've played around with these and 4435's for years trying to get the bi-amping right. I know many don't like these bi-amped or anything bi-amped for that matter, everyone to their own, however I did find it is difficult to get the 4430/4435 sounding right,.... however when you do they sing wonderfully ...... don't care what anybody says and they are as dynamic as hell !!! Now If you are interested, the process that I found to set up the drives to the LF and HF sections of the monitors to achieve this is as follows (and this assumes the correct cards are installed in the 5235, dip switch 3 is on for flat response and both amps are the same rated power output and gain) 1) set both amp attenuators to flat out, 2) attach an 8 ohm dummy load across the Left channel LF amp first, 3) place an oscilloscope or dB meter across the dummy load, 4) inject a 70Hz sine wave into your pre amp, and adjust the volume control of your preamp to create a suitable voltage across the dummy load, say 20V p-p or xx dB, 5) now change sine wave frequency to 10KHz leaving the volume control at the same level, 6) Turn off the LF amp, disconnect the dummy load and then connect to the Left channel HF amp output and then turn on, 7) now adjust the HF drive control of the 5235 to achieve the same voltage across the dummy load, 8) turn HF amp off and connect dummy load back to the Right channel of the LF amp, 9) repeat setup process for the Right channel .... Do not change the volume control setting during this process. After this process you can then adjust the dip switches to how you wish.

Now many will critasise the 5235 for all sorts of reason and then claim that another vendor type is better even though they use the same chips and more of them and the same topology, however since this is a JBL forum and not a Ashley or Nelson Pass forum I won't go there, however I can comment on the DBX crossover and that is it sounds very harsh compared to the 5235, the BSS FDS360 is another very nice sounding crossover with excellent detail. You can improve the stock 5235 with a capacitor and chip upgrade; this does provide sonic improvement from standard.

I also use an Aphex -10dBu to +4dBu level interface to drive the 5235 with the correct operating level therefore reducing any S/N issues, if you go down this path then you can probably attenuate the input attenuators on your amps so as to reduce the drives to them.


Forget about trying to use a RTA ..... too many room variables etc.

[timc]

Forget about trying to use a RTA ..... too many room variables etc.


I'm with you right up to this point. What we hear and percieve is a function of the speaker AND the room. In some setups a slight rolloff or increase in HF will do the trick.

Personally i would do the voltage check first, and then confirm with RTA or impulse response. If only the first was necessary, then EQ/DRC would be pointless.

[jblbgw_man]

I'm with you right up to this point. What we hear and percieve is a function of the speaker AND the room. In some setups a slight rolloff or increase in HF will do the trick.

Personally i would do the voltage check first, and then confirm with RTA or impulse response. If only the first was necessary, then EQ/DRC would be pointless.
Slight disagreement on the function and the intention of the electronic crossover, this is NOT to provide some sort of room eq .... don’t forget this is a singular crossover point of 1kHz, this will not balance a room ….. get the monitors balanced first, after all what we are trying to get right first here is the very critical crossover point that the 4430/4435 requires, then attack the room anomalies with the aid of a RTA if you wish, maybe use the 2 front controls of 2kHz and 12kHz cut and boost, if this does not provide the result you are seeking with regard to room response then maybe use an electronic equaliser if you see fit to provide whatever curve you desire.
:cheers:

[timc]

Agreed.

However, i have found that many rooms have a tendency to have a slightly uppward or downward curve as a function of frequency. In theese cases you can actually "tune" the sound by raising of lowering the whole topsection of the speaker. I'm of course talking about just slight adjustments. Usually within +-1dB

I am in total agreement that anechoic response should be in place first, but i got the impression that this was not a possibility. With your method of testing the voltage, you have to rely on the accuarcy of the speaker.

It seems that you and are in agreement, but look at this from a slightly differnt point of view. You want to emulate the passive network as closely as possible. I look at active biamping setup, as a tool to get things even better, before starting with EQ and room correction.


Happy easter hollidays!

[jblbgw_man]

Agreed.

However, i have found that many rooms have a tendency to have a slightly uppward or downward curve as a function of frequency. In theese cases you can actually "tune" the sound by raising of lowering the whole topsection of the speaker. I'm of course talking about just slight adjustments. Usually within +-1dB

I am in total agreement that anechoic response should be in place first, but i got the impression that this was not a possibility. With your method of testing the voltage, you have to rely on the accuarcy of the speaker.

Yes fair comment, but for this to be so the room would need to have an upward or downward slope starting at 1 kHz in this instance with the 4430/4435, this method you suggest may be more easily achieved or suited in a multiway system. Please don't forget that the sole purpose of this exercise I have outlined was purely to get the crossover point correctly balanced in the 4430/4435 which through my experience is absolutely critical, any adjustment of the 5235 crossover that deviates from this to combat room anomalies will of course detract from this target.

As a side issue if the crossover is not linear phase, (which the 5235 4430/4435 crossover cards are not) then a difference in drives to the drivers will affect lobbing as well I think.

[timc]

Yes fair comment, but for this to be so the room would need to have an upward or downward slope starting at 1 kHz

a difference in drives to the drivers will affect lobbing as well I think.


In my experience, many systems have a sloped cure almost all the way. But i get your point.

I'm unfamiliar with the term "lobbing". Didn't find it easily on Wikipedia. I have no idea what the Norwegian word is. Can you explain?

[jblbgw_man]

In my experience, many systems have a sloped cure almost all the way. But i get your point.

I'm unfamiliar with the term "lobbing". Didn't find it easily on Wikipedia. I have no idea what the Norwegian word is. Can you explain?


Sorry .. Typo lobing with one b ....... here are a couple of links that may explain it for you http://www.audioholics.com/education/loudspeaker-basics/filter-crossover-types-for-loudspeakers http://www.aes.org/e-lib/browse.cfm?elib=11762 http://www.birotechnology.com/articles/VSTWLA.html

I'm sorry I look at it from an antenna array perspective, for example the TV Transmit antenna in your city (if it is a large one) is made up of numerous dipole antennas in a vertical array and normally a 4 or 5 faced "stack" for polar coverage. It is the intentional practice to introduce calculated phase differences between each of the vertical dipole antennas to provide a "tilt" to the radiated pattern which then controls where the RF energy is concentrated (the coverage area), this is no different to loudspeakers that are placed in a vertical array caused by the interaction of each driver to the other. In fact Linkwitz in earlier papers refers or used to base his calcs on dipole antennas. The difference is that on a TV Transmit antenna (if situated high above a city) is the amount of tilt in degrees from horizontal is more significant than what is desirable in loudspeaker alignments.

I'm sorry .. I really have digressed from the original discussion and wish not to detract from my original point of discussion.

Have a happy and safe Easter!:cheers:

[Mr. Widget]

Forget about trying to use a RTA ..... too many room variables etc.I agree. They can be useful in general, but they are easily fooled by reflected sound and mic placement and can give erroneous info.

I'll take your word for it that using 70Hz and 10KHz sine waves work in your room, I prefer a wider band of noise since any given speaker could have a dip or peak at a particular frequency especially at lower frequencies. A 70Hz signal could easily be +/- 10dB from it's anechoic level depending on room/mic placement.

I think using your technique, I'd be inclined to try two or three high and low frequencies and average them... I would also look at the low frequencies between 100Hz and 500Hz since these should be less influenced by the room.

Of course if you are measuring a dummy load with an oscilloscope, that takes the room entirely out of it. I suppose as long as the signal generator has a linear output almost any frequencies should work... I guess I'd still try a couple of highs and lows to confirm the electronics and signal generator are linear.


Widget

[grumpy]

Dummy load and scope or wideband ac voltmeter is valid.
Amps with different/fixed gain -could- be accomodated with 5235
adjustments, but you'd lose some ability to optimize for s/n.

[jblbgw_man]

I’m sorry if you have misunderstood Mr. Widget, the reason for using 70 Hz and 10 KHz is purely and solely because if you analyse the voltage drives for the 4430/4435 crossover cards then you will find these spot frequencies are in the “flat” part of the pass band, well before the filter takes effect. These spot frequencies have absolutely nothing to do with room characteristics at all. Remember I am making these measurements into an oscilloscope or HP dB meter in my case and NOT into a room. Yes you could use other spot frequencies as well but they have to be in the “flat” part of the pass band for this technique to work. This is also why I stated setting dip switch 3 on the 5235 for flat LF response initially to remove that filter effect.

In fact my response to this thread initially was purely to inform how I achieve the correct crossover “balance” on the 4430/4435, I did not intend to enter the room characteristic debate as there are waaayyy too many variables, this is best left to the end user and I wish not to enter this debate. This is about the correct crossover balance or drives which I have found on the 4430/4435 to be very critical for correct sound balance. Also you will find all modern synthesised frequency generators have a linear output unless they are faulty, yes I did leave a step out in this process and that is that I still do check this as well and take nothing for granted.

To sum up, get the 4430/4435 crossover balance right first using spot frequencies into a dummy load ..... Then worry about the room characteristics later and apply as much equalisation as you deem fit to achieve what you want. Personally I don’t............ and don’t try and use the 5235 as some sort of primitive room eq tool.

Grumpy, this is why I use the Aphex -10dBu to +4dBu converter and apply attenuation on the input of my BGW’s, you will find most of these commercial or professional crossover networks specifications regarding SN are based on a +4dBu nominal input and not -10dBu, if you feed these -10dBu then of course you will have noise problems, in fact in this case you would be 14dB worse off than if you feed it +4dBu nominal.

Happy and safe Easter to all.:cheers:

[grumpy]

I hope your clarification/elaboration is read, and we haven't scared off the
originator. :)

[jblbgw_man]

I hope your clarification/elaboration is read, and we haven't scared off the
originator. :)
Oh sh$t ..... appologies... I suffer from :blah:

[Zilch]

R/S SPL meter will mount to a tripod.

Biamped, 4430 adjustments remain operative:

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4430LR.pdf

You gotta be using the 4430 cards in the 5235.

I was expecting a major difference also.

It didn't happen, and passive was "better...."

[jblbgw_man]

I think for 4430/4435 owners who are contemplating this exercise it is important for them to acknowledge that for whatever reason that some people have tried bi amping these and have concurred with Zilch that there was either no or degraded performance in going down this path, it is also equally important for these perspective bi amping experimenters to acknowledge that there are people like myself who have done this and found the total opposite and won't go back. The important thing is to try it for yourself and you determine what you like better. :cheers:

[Robh3606]

The important thing is to try it for yourself and you determine what you like better.

What he said. :yes:


Rob:)

[RichK]

I hope your clarification/elaboration is read, and we haven't scared off the
originator. :)

LOL. Naw, you haven't. Work keeps getting in the way of my hobby. I'll get to it this weekend, if not sooner. I believe I can use my computer for a source for both the pink noise and specific frequencies. For the present moment I'm not bi-amping.

Thanks so much to all for the help!!!!

Rich