Crossover mods and speaker efficiancy?


I was just wondering if anyone can tell me if it makes sense that with complete crossover mods(caps, coils, resistors, and internal cabling)that the speakers would draw more current from my amp? My speakers are Hales T5's with totally upgraded crossovers. I am using Dynamicaps for the tweeter section, Dynamicap,Audiocap and auricaps for the midsection and Solen/Axon for the bass area. My coils were replaced with Solo foill coils(16guage for tweeter, 14 guage for mid and 12 guage for bass). Finally as well the internal cabling was replaced with cardas chasis wire of three guages for the three drivers.
My question is that should these changes make my speakers less efficient or draw more current from my amp. I have a Pass X250 which has a meter on it which indicates how much current is being drawn and when the amp is going out of A mode. When the needle moves at all it's out of A mode and into AB mode. What I have noticed with the crossover mod is that the meter is reading that the speakers are taking very much more current than before the mods. The needle bounces to around the 2 or 3 O'clock point on loud passages where as before the mods the needle rarely passed 12 or 1 O'clock. The sound is way bigger sounding and I suppose the bigger sound is due to the larger current draw but I'm not sure. Would this type of crossover mod make my speakers less efficient in that my amp is obviously working much harder than before but the sound is much bigger than before. Any opinions would be greatly appreciated. I should note that I can listen to louder levels of volume of the music as the sound is clean and doesn't sound "loud" as the speakers now tend to have less distortion and I can play loud without being annoyed. The needle on the X250 meter now tends to bounce around alot where as before it just wiggled.
mitchb

Showing 5 responses by sean

In many cases, one need not even change components in a crossover to achieve better performance. That is, by laying out the existing parts in a more precise manner, it is very possible to lower noise, distortion, crosstalk between circuits, improve power transfer, improve transient response, reduce the number of connections, etc...

This is what i did to my Father's speakers and the difference is HIGHLY audible. Only changes made were to the wire feeding the drivers. We were able to go from 61 connections per crossover board down to 23 per board. This eliminated 60%+ of the "cluster" that was built into the signal path from the factory. While we also performed other cabinet modifications, my personal thoughts were that the crossover / wiring changes were most responsible for the drastic sonic improvements that we heard.

My Father invited over one of his friends to listen to his system, not telling him what was done. This person was very familiar with my Dad's system. As a point of reference, they both ran the same amp and had the same brand of speakers. The speakers that this gentleman have are actually two models up from what my Dad is running and retail for over $6k per pair.

After hearing the difference in peformance in my Father's system and being quite stunned, he asked what was changed. After my Father explained what was done and showed him the pictures, he asked if we could modify his speakers. Much like what Jonbok pointed out, it must be pretty dis-heartening to find out that your $6K+ investment bought you speakers that were far from optimized. Having proof right in front of you that your speakers sound quite poor compared to what they were capable of is NOT what you want to find out after shelling out that kind of money. Then again, one would hope that the manufacturer was intelligent enough to produce a proper design and impliment the existing parts in a more precise manner, but in most cases, they aren't and don't.

As in the above example, i'm not even talking about using higher grade / lower loss parts in some speakers. Like i said, we were able to achieve MUCH better results just laying out what was already there in a more precise manner. After looking at and playing with dozens of crossover circuits, i know that this specific situation is not unique either.

As a side note, even though the parts in the crossover had thousands of hours already on them, the sound of the speakers changed VERY noticeably. I used the Ayre Acoustics "Irrational But Efficacious" disc ( track 7 ) for 72 hours non-stop. After that, we ran the entire disc mixed with some other discs on repeat for 10 more days. One would never believe that these were the same speakers that we started off with, although the only components changed in the speakers were the wires. On top of that, the wiring that i used cost pennies per foot. As "cheap" as this cable was, it was still FAR superior to what was in there from the factory. Sean
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Parts should be as close as possible so that you don't have to use jumper wires between them. You also don't want to keep the factory legs on the caps / resistors real long. That is, point to point from one part to another is ideal, so long as the parts aren't so close as to interfere with each other. Inductors can actually be quite close to each other so long as they don't share common orientations. Sean
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The amplifier is actually loading into the speaker better than it was before. The better it loads up, the more power transfer and control that you'll have. After all, the amp can't control the speaker if it can't load power into it in both a timely and efficient manner. The fact that the sound is cleaner even though you are passing more power tells you that the speaker mods were quite worth-while.

As a side note, you're probably experiencing much of what i've been talking about now for several years. That is, the liquid and effortless reproduction at high volumes that one experiences with a true "high power / high dynamic headroom" system. With such a system, the sound doesn't appear to be near as loud as it really is, so you can listen longer with far less fatigue. That's because distortion adds a LOT of "apparent volume" and is very fatiguing. You've taken steps to reduce those distortions via improving power transfer and now you're reaping the benefits. Sean
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Trelja: Once again, right on the money. As usual, you summed my thoughts up quite well : )

Herman: Mitch stated that the amp is delivering more power, but also sounds much louder and "bigger". As such, it is hard to imagine heavier gauge inductors and lower loss components being "less efficient" or a greater "wattage waster". I do agree that crossover points may have shifted slightly. However, i sincerely doubt that Hales was using THAT sloppy of parts tolerance in their speakers. They would have had to be horribly out of spec to achieve the shift in values that would cause the changes in required drive levels that Mitch is talking about.

I have to agree with Trelja's assessment above. That is, the better that your system gets, the more likely you are to listen to it louder. The lack of grain, glare and distortion are no longer an irritant, so you end up compensating for those factors with increased volume. Not only do you end up "rocking out" more, you end up enjoying it more too.

One problem with this type of situation though. Now that you've increased power transfer into the speakers, reduced passive losses and are also listening louder, the drivers have a LOT more thermal stress to deal with. Be careful. Your either well onto the road of "sonic bliss" or "thermal melt-down". Hopefully, the drivers and crossover freq's / slopes were well chosen by Hales and you won't run into problems. Sean
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What you did works pretty well. This allows one to keep the components for each band-pass in close proximity to each other, keeping the path short, while also reducing crosstalk between band-passes. At the same time, if properly done, one can provide a direct path to the binding posts for each circuit, kind of like a "star circuit" that hovers around one set of connection points. Due to the placement of some binding posts and the size of some crossover networks, direct connection from the parts to the binding posts is not possible, but using an arrangement similar to the one mentioned above with a separate modular board also works quite well. Sean
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