Crossover settings

[Sasquatch]

I am currently using a Furman TX-3A tunable crossover in my system. I am running it in 3-way mono tri amping my mains. For the main enclosures I'm using Peavey 3020HT cabinets with a Peavey MFX-1 horn stacked on top. I have a Souncraft Spirit board. Have everything panned right. Coming out of the right output into channel 1 of an Alesis dual 32 band graphic EQ. Out of EQ into crossover. Using a Peavey CS800 for highs, a Peavey CS800 for mids and a CS1000X for the lows. When adjusting the mid frequency on the crossover I get some loss at certain frequencies. It almost sounds like a dirty pot. What is a good starting point for mid frequency setting on the crossover? Lows? I have the manuals for each componant. Should I go with a 3 way stereo crossover to use both outs on the board and EQ and still be able to triamp? This crossover is nearly 24 years old. Might be time for a new one? Tried to upload the manuals but couldn't. Email me at and I can provide them. Thanks for any help

[museav]

You'd need the manual for the 3020HT and might have to contact Peavey for that but from some of the Peavey crossover manuals from that era that reference the 3020HT it looks like they suggest a sub to low crossover around 100Hz, a low to mid crossover around 400Hz and mid to high crossover around 1.5kHz. Of course that is with their crossovers and whatever filter types and slopes they used, so your results may vary.

The 3020HT is a full range box so I am not sure why you have the MFX-1 horns on top or how they are wired, but that could be part of the problem, I'd start by pulling those and seeing if it helps.

You might also try setting the crossover with the EQ flat and just one speaker turned up to make sure you are setting it for the speaker and not getting the EQ or any speaker interactions involved.

You may also want to verify driver polarity, if some drivers were repaired or replaced and wired backward that could cause some odd results.

[Sasquatch]

I have the manual for the 3020HT. It has a full range in and then low, mid, and high in for triamping. Using the MFX-1 horns because in my opinion they sound better. I run the highs into the MFX-1 horn and then out of it into the high input on the 3020HT. Just started doing this as an experiment. The tweeter in the 3020HT does provide a certain "crispness". The crossover settings you mention is right around where I have it set by my ear. I'm still wanting to use both channels of my EQ. Should I just upgrade to a 3 way stereo xover? Then I could use left/right out on the board to channel 1 and 2 on EQ then into xover. Just came back from my rehearsal space. Anywhere from 1.5 to 2.5 for the mids sounds pretty good. Still get some dropout when sweeping the knob. I'm thinking this is a dirty pot. I've attached the 3020HT manual as a jpeg. Thanks for any suggestions. Just started rehearsing again after a 6 year layoff. So I'm learning again. It's like riding a bike, You never really "forget" you just have to get up and going again. I've tried to upload the 3020HT manual as an attachment but can't get it to work. I can send it you by email. Thanks.

[museav]

I'm concerned that because they use totally different drivers and horns and because the 'high' input on the 3020HT still uses part of the internal crossover in the 3020HT (, then the MF1-X in parallel with the 3020HT high input along with acoustic interactions between the horns is likely at least part of the problem (and also likely presenting a low load to the amp).

The 3020HT is actually a four-way box that can be run full range or tri-amped. When run full range the is a 6dB/octave low pass filter at 400Hz for the lows (the dual 15"). Then a matching 6db/octave, 400Hz high pass filter and a 12dB/octave, 2.2kHz low pass filter for the mids (dual 10" drivers). The 'high' section actually has two components, a compression driver on a horn and a 'super tweeter'. The compression driver an horn gets an 18dB/octave high pass at 2.2kHz, however there is also an 18dB/octave low pass at 8kHz that is part of the internal crossover and is in the loop even when tri-amping. There is also a 24dB/octave high pass at 8kHz for the 'super tweeter' that is part of the internal crossover and always in the signal path.

So the 8kHz 18dB/octave low pass and 24dB/octave high pass internal crossover is always in the signal path even when tri-amping. When you wire the MF1-X in parallel, which should have a 600Hz, 12db/octave high pass, you have added another complex device in parallel, which probably messes with the internal crossover. That could certainly be part of problem. Adding to this, with the MF1-X in parallel you have two devices with different ranges, different impedances and different sensitivities in parallel, so the resulting combination cause variations in the output of the different devices over frequency.

Finally, with the MF1-X overlapping in frequency with two devices in the 3020HT and being separated from them by some phsyical distance, you are also likely getting some relative phase interactions between the sources. The effect of summation and combfiltering might audibly affect the response as you change the crossover point.

[Sasquatch]

I see. So either one or the other. Got it. What about stereo 3-way? Still using either the MFX-1 horns or the 3020HT horn and tweeter. This would then allow me to use both outs on the board and EQ. Or what about another 3-way mono crossover and run each stack with it's own crossover? To me this sounds like it would present problems trying to get both stacks to match up. Just asking. You don't know if you don't ask. When having the CS1000x turned down (low amp) and the CS800 turned down (high amp) leaving only the CS800 used for mids turned up, while adjusting the croosover point I hear dropout in the 2 tens in the 3020HT. Do you believe this is part of the problem of having the MFX-1 horn and 3020HT horns patched together? Is it also being caused by the internal crossover of the 3020HT? I understand your post about presenting a low load by patching both horns together and had not considered that Thanks for your help.

[Blah067]

sorry for a slight change of subject...

Why pan everything right? Is there no mono out?

[TimmyP1955]

There will be no advantage to using the second channel of the EQ. One board out into one EQ channel into one XO channel into as many amp channels per output as you want is fine.

If you have the Alesis dual analog EQ - which is hated by more pros than any other - you should is replace it with a dbx1231. Or, use this as an excuse to find a deal on a clean used DriveRack PA or DriveRack 260.