6 dB per Octave Passive Crossovers

[LowOhms]

Hmm, can't comment WRT resistor banks Vs a single large resistor in amp design being audible, but at the speaker power level, resistors have the same type of thermal amplitude modulation distortion as a driver VC, 'crushing' dynamics, so can make an audible difference in some cases and why I use many small resistors instead of one big one same for the same reason I would use multiple smaller drivers Vs just one big one in a high efficiency, wide BW app. If nothing else, the lower the heat dissipation/'clamping' required, the less critical the resistor material composition, ergo can be much less expensive if you discount the extra labor of assembling it.

Must get down to level 7 before the firestorm hits.......

GM

Hi GM !!

Nice to be able to talk to you. How about a whole other area of thinking about multiple resistors in crossovers, etc., that perhaps we should consider. ( My own idea, and I speak and write very differently than many do, so bear with me.)

First, allow me to tell you my speaker crossover experience from two weeks ago !! It was really neat. I have an old pair of KLH 5s which has its internal wire optimized - replaced ( from the crossover the the drivers ), and I have placed the crossover OUTSIDE of the speaker enclosure. The KLH 5 crossover uses a 15 Ohm 5 Watt series padding resistor on the two four inch midrange drivers. ( Same drivers as in the old KLH radio, a nice smooth driver ).

First, I replaced the 15 Ohm stock resistor with a 10 Watt non inductive "yuppie - audio quality " resistor. It was a LITTLE bit better, cleaner - yes, but really not worth the effort nor the cost. Next, I replaced the 15 Ohm Non Inductive with two Dayton 30 Ohm 10 Watt non inductive resistors, closely matched. Holey COW and Jumping Jimmy. My reference cut, Chet Atkins and Jerry Reed "Sneakin' Around" portrayed their two voices in a manner, and at a level, I had never heard on any system I have played it on over the last ten years. ( I am referring to improvements in tone, spatially, and in fine resolution ).

The following is SPECULATION on my part, as to what was happening. GM, I wanna tell you , I think its more than just "thermal amplitude modulation " alone. I want to propose to you one additional mechanism. I believe an INCH of bad wire, in a critical place, can degrade, maybe even ruin, the musical experience we seek from our systems. You mentioned above..... "crushing dynamics".... YES !!! that is where I am going.

Has anyone ever addressed the PUny lead out wire on a resistor, ........ is it 20 or 22 AWG ? Is it steel or copper? How come we try to run the whole audio signal ( the whole orchestra ) though an inch ( total ) of CRUMMY PUny wire, going into and out of that crossover's resistor ?? THAT mechanism is robbing us of some of the good we would derive, had it been properly addressed I say !! Just going from one to two resistors, in a series circuit to the driver, offers a performance improvement. WE have two wire paths now. Instantaneous PEAK music signals are no longer being clipped. The amplifier couples to the driver's voice coil better.

The speaker, assuming its in a good system ( this can be a BIG assumption ) plays at a higher performance level - and it is audible. It is also important to closely match the two paralleled resistors, to obtain optimum benefit. That way, one does not, in any way possibly "buck" the other.

Regarding my contention of "an inch of bad wire in a critical place can ruin the musical experience", I had one other UNUSUAL experience to share, in addition to the KLH 5 speaker crossover. It was instructive. Three years ago I took a EICO HF-81 ( P-P 6BQ5 receiver ) and replaced a 5/8ths inch wire run, from the plate of the input tube, to the grid of the phase splitter ( across a 9 pin miniature tube socket ). I changed this short span of wire from stock ( bell wire ) to one, than two, then three runs of Kimber TCSS wire, and listened. In each case, the sound was (a) different and (b) better.

Of course, this was a DIRECT COUPLE, so, the whole orchestra was going through that 5/8ths inch span. Anyway, GM, my subjective listening experiments made me very AWARE of the effect or wire, internally, in key places. So, I am suggesting using two resistors, in series, instead of one...two wire paths !!

We are thinking in terms of keeping the music intact, in terms of dynamic performance, and preserving the instantaneous peak performance of music. If it is clearly audible on a KLH 5 and on a 12AX7 in my EICO HF-81, running at 1 mA., (which is also a CAT preamp !!). Might it also apply to optimally powering our drivers ALTEC ?? 'You bet cha'. Every Altec compression driver gets padded down to the lower efficiency woofer, usually resistively. Lets smell the roses before we die !!

Jeff

Our doubts are traitors, And make us lose the good we oft might win. By fearing to attempt. William Shakespeare, "Measure for Measure", Act 1 scene 4.