4430/4435 Help

[Music Lover]

Hi everybody, I have a set of 4430's and 4435's :D which I am atempting to run bi-amped with a JBL 5235 Active Crossover Network (with correct 4430/35 cards installed), as I do not have the owners manuals for either of the loudspeakers, I have a couple of questions that I am hoping someone else has encountered and is in a position to advise me.
1) As the cross over cards are 12dB/octave is a phase reversal required for the HF driver.
2) Does the HF driver require any attenuation with reference to the LF driver.
3) The JBL brochure suggests amplifier powers of 400W for the LF and 150W for the HF which equates to a 4.25 dB difference, does this suggest that the HF driver should be attenuated by 4.25dB in relation to the LF driver or is this because there is more energy in the LF spectrum than the HF spectrum in music.
4) The passive crossover schematic implies that this is not the case as both LF and HF paths are fed from the same point when not bi-amped.

This has come about by the fact when I feed both drivers with the same level there apears to be overwhelming HF energy, when I adjust the HF drive for "what sounds right" it equates to around a 3dB reduction in HF drive. Unfortunatley I do not have an analyser to measure what is going on, however this I believe this should be able to be resolved without the need of an analyser ................ all opinions and advice would be greatly appreciated.

Would anybody have a soft copy of the 4430/35 loudspeakers which they would be willing to email me or post here.

Many Thanks

[Rolf]

Hi, and welcome to the forum.

The only thing you should need to do is to put the switch on the back in the bi-amp position, hook up the rest of your gear and play.

The two amps do not need to have the same output power, just have enough.

Of course you have to adjust the MF and HF level with the L-Pads according to your room.

[grumpy]

Amp power rating is relatively unimportant regarding matching levels between the drivers
(ultimate sound level, and headroom to avoid clipping... yes, as Rolf indicated).
Amp gain, and the 5235 level settings, are though, as well as whether the amps are
phase-inverting or not (should match or you'll have to swap one of the biamp speaker
input leads on both speakers).

Matching levels by ear might get you to an emjoyable state... measuring them would be
better. (Sorry, I don't have the manuals)

-grumpy

[Hofmannhp]

Hi Peter,
a pleasure to (try) to help you....

you can use 2 identical amps for all channels.
Minimum power should be 200W p/ch for a kick ass bass.
Don't be afraid of a to high power for the high frequency unit ,I guess 2426J or 2421J, (interesting to know). When you switch on the terminal plate of your 4435 to "external" there are still passive parts in the circuit which handle the power in a right way also for the high frequency driver. When I found the schematic.....I will post it (N3135).
Additionaly I can tell you, when used in "external" crossover mode, the L-pads in the front of your speakers are also usable. The + wire for the heights then "crawl" through a cap with 2.5uF then through an ind with 0.04mH before they reach the resistors with 20 Ohms (in line) and 10 Ohms (parallel) to the high driver.
Hope this helps a little.

regards

HP

[Zilch]

Not that it much matters in this instance, but for the record, the drivers are 8 Ohms, i.e., not "J."

You adjust the overall balance between LF and M/HF with the HF controls on the front of the 5235, according to the amplifiers used.

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

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4435LR.pdf

http://www.jblproservice.com/pdf/Network%20Schematics/3134%20Network.pdf

http://www.jblproservice.com/pdf/Network%20Schematics/3135%20Network.pdf

To the best of my knowledge, there never was a manual for 443x; they were sold into use by professionals presumed to know how to apply them.

http://www.jblpro.com/pub/obsolete/443035.pdf

[Music Lover]

Ok …. Thanks guys for your posts I do appreciate your opinions, however I was hoping for a more technical approach to the issue. For simplicity’s sake and clarification let’s state that the amplifiers are identical as in model and output power and gain/sensitivity.

I’m glad we agree that we have to adjust the HF level settings on the crossover with reference to the non adjustable LF output, but the million dollar question is By How Much. Matching levels by ear is a nonsense, yes maybe fine tweaking with the MF and HF level controls on the front of the monitors if you wish to tailor the response Afterwards but NOT to set up the drive levels from the crossover ….. this dB difference is a known CONSTANT and should be stated Somewhere!! . Now there are clues in the literature that JBL produce, as in the recommended amplifier power … remember a minus 4.25 dB rating for the HF section with reference to the LF section or in the Technical Manual a reference to the Aural Sweep Tests … LF section at 10.0 Volts and the HF section at 2.83 Volts ….. a mere 11 dB reduction for the HF section with reference to the LF section … is this to produce the same acoustic output per section ??? …… don’t know !!!

Now trust me I am not scared of using high power amps and I am a firm believer in as much headroom as practable and as the pocket will support. I can read schematics …. In fact very well, but the million dollar question is By How Much To Reduce The Drive To The HF Section with reference to the LF section. Now I believe this dB figure is out there Somewhere … But Where ???

I have run some sweep tests of the 5235 filter sections and I believe that a phase reversal is required to the 4435 HF section from the power amplifier because of the 12 dB filter slopes and the 180 degree phase inversion at the cross over frequency, this is evident when you sum the outputs on sweep….. No surprise here phase reversal of the adjoining drivers have been going on from the beginning of time when using 12 dB filter slopes.

I have since posed the question to our trusty JBL dealer and am hoping that in time I will get a sensible reply of which I will post back here for all you guys that care and are running your 4430’s and 4435’s Bi-Amped.

My bet is HF phase reversal and an 11 dB reduction in drive to the HF input of the monitors with reference to the LF input … am I right?? …. Don’t know … does anyone else know …. Hopefully.

[grumpy]

My bet is HF phase reversal and an 11 dB reduction in drive to the HF input of the monitors with reference to the LF input … am I right?? …. Don’t know … does anyone else know …. Hopefully.

I seem to recall I flipped the top end phase around and liked it better...
IF I have time tonight, I'll hook it up and measure it. 4430's, identical amps,
5235's w/ 4430/4435 cards. Didn't have the tools before.

I'd be interested if you get an official response. -grumpy

[grumpy]

See attached. I would recommend you go through the 5235 manual if you
haven't already. Note a 10dB difference at the crossover freq... inverting the
polarity of the HF section input gives the constructive driver sum (green-ish).
I presume this is correct. I'll have to listen to something other than test tones
to see if I have a strong preference.

Gain on the 5235 is not calibrated, but I -think- it's about unity gain for both
LP/HP sections when set to "8", which is where I had it set for these
measurements. L-pads were set to the flat "0dB" positions. Mic ~24" from
floor (carpeted) and ~1m from 4430, straight on. HF/LF balance seemed
reasonable in my listening space. (5235 DIP switches set to FLAT)

-grumpy

[Music Lover]

Whilst still eagerly awaiting to hear back from my local JBL distributor I decided to do some more sweeps of the 5235 xover network with interesting results. The plots are 1) xover set to unity gain or both LF and HF outputs set to the same level and summed .... a typical 12dB/octave slope crying out for phase reversal .... right !! 2) same outputs levels for LF and HF but now with the outputs subtracted .. simulating a phase reversal in the HF section .... right !! 3) HF output set to -11dB and SUMMED .... yes summed ... big suprise and 4) HF output set to -11dB and subtracted .... what a suprise!!

I supose the problem using 12dB filter slopes and having to reverse phase the adjacent driver to eliminate the hole at the cross over frequency is that the rest of the band is out of phase to the preceeding driver, however looking at these sweeps it would apear JBL have worked out a way around it .... everything "in phase"

I now draw the following revised conclsion .... HF driver "in phase" with the LF section and at -11dB down from the LF section. But it would still be nice to hear this from JBL themselves.

I'll keep you posted.

[Music Lover]

Thanks Grumpy .... now I am scratching my head .... let me get off the RTA and do some listening tests.

Cheers

[grumpy]

If I can check something else or explain my setup further while I have this
configuration in place (next few days), let me know. Can you verify what 5235
front panel setting resulted in unity gain for the HF vs LF outputs (was it ~8)?
Gain of HF vs LF is +6dB at maximum.

I've diff'd the two plots for comparison. -grumpy

[Music Lover]

If I can check something else or explain my setup further while I have this
configuration in place (next few days), let me know. Can you verify what 5235
front panel setting resulted in unity gain for the HF vs LF outputs (was it ~8)?
Gain of HF vs LF is +6dB at maximum.

I've diff'd the two plots for comparison. -grumpy
Cheers Grumpy I appreciate your time and efforts ..... I have spoken to our JBL dealer today and discussed with him the findings thus far, after viewing my plots and looking at the Technical Manual and the Sweep Tests they tend to agree "no phase reversal" of the HF and with a 11 dB reduction in drive to the HF section, however they apparently are still going to discuss it further and then maybe email JBL Engineering ..... good service!! I will get to the bottom of this for once and for all as it has been annoying me for some time. Re: my 5235 "settings" I replaced both pots some time ago with 10 turn trim pots so my settings are irrelevant to a standard 5235, however ..... may I suggest you download the RTA I use from http://www.trueaudio.com/ (http://www.trueaudio.com/) the 1 octave is for free, I use the 1/24 Octave for greater definition but the 1 octave MAY be ok for setting up your 5235, I used spot frequencies of 60 Hz (10Hz above our mains frequency) and 10kHz. The RTA is a bit of a "toy" but I have reasonable quality sound card and I think you will find most soundcards are reasonably flat ....... Accuracy in level is not paramount for most measurements ..... we are after Relative and NOT Absolute !!!! RTA is fine for this .... although a phase function would have been nice and I did recommend this to them some years ago but it must have got too hard. I have 1 more test which I will do in the mean time, generate some pink noise from the RTA feed that through the system, I have a Behringer ECM 8000 condenser measurement mic which I will put through a small Soundcraft mixer (for the phantom power) then feed that back into the RTA, this should verify things .... not real user friendly so you can see why I tend to use it as a last resort.

[Ian Mackenzie]

Try searching the forums.

Giskard has discussed this at length numerious times.

http://www.audioheritage.org/vbulletin/showpost.php?p=8214&postcount=6
http://www.audioheritage.org/vbulletin/showpost.php?p=8250&postcount=13

[grumpy]

Thanks Ian,

Here's the voltage drive:

http://audioheritage.csdco.com/vbulletin/showthread.php?t=2226&highlight=4435+voltage+drive#4


-grumpy

[grumpy]

...then to prove it to myself (and answer the unity gain question for anyone
else that was interested), voltage drives from 5235 w/ 4430-4435 cards
installed and measured at power amp input are attached (R & L channels).

HF levels on 5235 were set to nominal "8" and then tweaked and
remeasured. I was about one dB off initially from unity gain
(HF set too high initially when setting to "8" by eye). The level control
is fairly sensitive.

With 5235 set to my satisfaction, I then tweaked the HF/MF controls
on the 4430 again for a compromise between L-R matching and flatness.
This was more of a pain then it might sound, as my L-pads/var resistors
all need replacement... (next obvious update).

One 6260 powers each channel.

Running the drivers all in-phase for this process yielded the response I'm
happiest with.

-grumpy