First. I have been lurking on the forum for a while and have finally registered as I have found the contributors very well informed and helpful. Second I am an amateur audiophile and not very experienced with internal electronic concepts and components and their integration into equipment beyond knowing what things are called. With that being said, so you know what you are dealing with I have searched through prior posts but I am unable to ascertain a definitive answer to my quandary. I recently purchased a set of 4435 monitors. The set came with a JBL/Urei 5235 external dividing network and the proper 4430/4435 crossover cards. However, the speakers are missing the complete internal passive crossovers (61461 Dividing Network) crossover, jacks and biamp switch). It does still have the front panel Lpad level controls. I am fine Bi-amping these and I have several options for amplifiers both Tube and SS or a combination of both with Tubes for the HF and SS for the LF channels I will probably test several variations of amplifier setups before settling on the one I like best. My amplifier options include a set of Krell KMA 160 (SS 2 Monoblocks), a Krell KSA 80 (SS 1 stereo amp), a pair of SS Adcom 555II (SS 2 stereo amps) and soon to be delivered Manley Studio 440 (Tube 2 Monoblocks). I have some nice options. Regardless, without the passive crossover, which to the best of my understanding provides some degree of protection to the HF driver and also splits the frequency for the 2 LF and MF woofers, can somebody explain exactly how I can use the 5235 dividing network without the passive crossovers but still using the Lpads and also incorporate the proper speaker protection. I also understand that there may be some additional consideration to protect the Tube amplifier.
How do I split the amplifier outputs to both the LF and MF drivers? I understand that the LF and MF driver have a crossover at at 100hz which must have been incorporated into the passive crossover which I dont have? The 5235 I assume will be taking care of the HF cutoff points for the LF and MF drivers.
The 5235 Crossover does have the matching 4430/4435 cards but I also understand from review of the manual that there are 5 Filter DIP switches inside the unit which also may need to be adjusted. Are there any recommendations for what settings to use? It appears this is useful for high pass filtering of the LF drivers to remove subsonic signals below the drivers capability which for the 4435 woofer I believe is 30hz. There is also a DIP to add 6db of boost to the filter point (with a caution that it draws 4x increase in power from the amplifier to cutoff octave? Is it safe to use this or should I not bother with the boost?
Additionally there are 2 notes in the 5235 manual 1) which state using a 50 watt resistor (2xto 3x the driver impedance) to shunt the reactive component of the driver below horn cutoff installed across the driver terminals and 2) a caution note when using Tube Amps and some SS amps wherein the user should install a 20W resistor (10x the drivers impedance) across the amplifier terminals.
I assume I wouldn't need any of this if I still had the passive crossovers?
Because I will directly wiring the Amplifier to the HF drivers the 5235 manual recommends inserting a capacitor in series. I believe the HF crossover frequency is 1000hz so according to the 5235 manual should I use an 40uf cap for the horn? or what size capacitor is recommended and does it matter which leg it is installed on (+ or -) and where in the chain (before or after the Lpads)? How do I incorporate the LPads into the circuit?
Also, I believe I read somewhere that the balanced XLR pins on the 5235 are reversed and I may need to have a custom cable made or otherwise swap the pins so that it will work with the Manley Tube amplifier which has the option of either balanced or unbalanced inputs (my preference would be to use the balanced inputs for the Manley).
So It looks to me like I need to
1. Install a capacitor in series with the HF driver somewhere? What value?
2. Install a resistor across the driver terminals to shunt the reactive component? What value?
3. If using the Tube amp install (another?) resistor across the amplifiers outlet terminals? What value? and is there any degradation of sound doing this for the SS amp also whether it needs it or not?
4. Install something to cutoff/crossover the frequencies between the LF and MF drivers.
5. Split the signal to LF and MF drivers
6. Reverse the XLR pins between both the Source and 5235 and also the 5235 and the Amplifiers? Seems strange that I would need to do this? is this correct?
This is not as straightforward as I had hoped. Lastly, I would also strongly consider purchasing a used set (if I could locate them) or having a set of passive crossovers built to insert back in the chain which would also give me the additional option to drive the speakers directly (passively) without the 5235 Active crossover. I know this is a long post with many questions and thank you in advance for reading and responding for any input anyone could provide. I have uploaded the 5235 manual and 4435 spec sheet.
Matt
Reply With Quote
