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.
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC˛ ±3db
Originally Posted by SMKSoundPro
I checked the switches again and they are in fact set in the default position.
Rich
okay. Thanks for answering my dumb questions.
Link: http://www.audioheritage.org/html/pr...bl/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.
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC˛ ±3db
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.
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.
4435, 4430, 4315, 4312B.
2 x Bryston 4BSST2, BGW 203, JBL 5235, Aphex 720.
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.
2213 + 2435HPL w/aquaplas + H9800 (Matsj edition)
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.
4435, 4430, 4315, 4312B.
2 x Bryston 4BSST2, BGW 203, JBL 5235, Aphex 720.
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!
2213 + 2435HPL w/aquaplas + H9800 (Matsj edition)
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.
4435, 4430, 4315, 4312B.
2 x Bryston 4BSST2, BGW 203, JBL 5235, Aphex 720.
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?
2213 + 2435HPL w/aquaplas + H9800 (Matsj edition)
Sorry .. Typo lobing with one b ....... here are a couple of links that may explain it for you http://www.audioholics.com/education...r-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!
4435, 4430, 4315, 4312B.
2 x Bryston 4BSST2, BGW 203, JBL 5235, Aphex 720.
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
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.
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.
4435, 4430, 4315, 4312B.
2 x Bryston 4BSST2, BGW 203, JBL 5235, Aphex 720.
I hope your clarification/elaboration is read, and we haven't scared off the
originator.
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