2. amps-preamps
  3. 1071667881

Do I really need a crossover when running 2 amps?

Last night I tried running my two Hafler amps bi-amped. One a DH500 to the horns, the other an XL600 to the drivers. I just purchased some inexpensive rca Y connectors. Wanted to see if the sensitivity of these two amps was close. They sure seem to be!
I must say I was floored with the result. Bass was much deeper and the highs much more clearer. I really didn't expect this result. I would think I would of needed a crossover to separate the signal from the preamp and then direct that to each amp. Maybe I do? I am a bit ignorant here.
Can you just split the signal from the preamp and run the output from one amp to the high connectors on the speakers and the output from the other amp to the low connectors on the speaker? I am thinking if I get a crossover, maybe I can get to sound even better.
Not sure I am going to do this, but like to know what I need in case I get the bug. One thing I am aware of is the more power you have the more apt you are to use it. I was listening to concert levels last night. Things where falling off shelves, it really was awesome. I am a bit old for this. I see a hearing aid in my future...

Also, I was thinking of trying silver interconnects, not sure I will be able to track down a silver Y connector, if I decide to keep they way I have setup now.

Anyway, any suggestions or info to set me straight sure be appreciated.
johnymac
eldartford
4,262 posts
 
Johnymac...Ideally each amp would be connected directly to a driver (woofer or tweeter), completely bypassing the internal passive crossover. This is OK for the woofer, but the tweeter should be protected against inadvertent LF inputs by a series capacitor. You could try it this way.

It is possible that the internal crossover has some extra components (Zoebel network) to tame a resonance of the driver. In this case it might be best to use portions of the X/O circuit, jumpering out the HI/LO filtering parts that become unneeded with the electronic X/O.
timo's avatar
timo
610 posts
 
Yes, you would have to disable the internal speaker crossover (i.e. by-pass it) and let the external electronic X-over send the correct signals to each driver of the loudspeaker.
gogamecocks
37 posts
 
Glad to see that you are still enjoying my old XL600!!!
sean
6,231 posts
 
I agree with El and Timo, but on different points. If you REALLY want to have a revelation, get rid of your internal crossover and go electronic. Passive bi-amping compared to active bi-amping with "direct drive" ( no passive crossovers between amp and drivers ) is kind of like the difference between bathing with your clothes on and off. One way works so much better, you'd have to be crazy to do the other once you experience the difference first hand. The difference in low level resolution, transparency and dynamics is eye / ear opening to say the least.

In order to do this and not run into problems, you'll need to contact the speaker manufacturer and get some help from them and / or find someone that can reverse engineer the crossover for you. As El mentioned, some speakers make use of notch filters, zobel networks, etc... Bypassing these would probably result in poorer performance, so you'd want to leave them in but get rid of the high pass and low pass sections. The more junk that you can pull out of the signal path between the amp and the drivers, the better off you'll be ( as a general rule ). Sean
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eldartford
4,262 posts
 
sean....In general I agree with your comment about the superiority of driving speakers directly (not through X/O components), although I can think of a better analogy than the one you used.

Of course I biamp between my subwoofers and the MG1.6 mains, but I have considered also biamping the MG1.6. However, Maggies are a queer breed of driver, and I suspect that the crossover, although a very simple circuit, may be important to the overall speaker performance. So, I do not intend to biamp the MG1.6.

However, I am open to the idea of upgrading the passive crossover using same-value better quality parts, for example air-core inductors. In your extensive experience messing around with speakers, what have you learned relative to the benefits obtainable by passive X/O upgrade?
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