Modifying Behringer CX3400 crossover - Page 2

Moondog55 · 17th August 2007, 07:26 AM

try these links
http://www.allansmusic.com.au/Product.aspx?p=53281

http://www.allansmusic.com.au/Product.aspx?p=53890
Still reasonably cheap
Ted

jeff mai · 18th August 2007, 03:19 AM

The unit I borrowed had minor (but significant) level discrepancies when both channels were set to the same level by the dial markings: 2-3db differences in some positions. Additionally, the crossover frequencies between the two channels were as much as 25% different when the dials were set to the same position.

This isn't necessarily easy to hear in a multichannel system until you fix the issue. These crossovers are great for what they are, but if I were leaving one in my system long term or evaluating other system components or changes, the problems need attention.

Moondog55 · 18th August 2007, 06:16 AM

Hi Jeff, must say that that isn't audible to my aging ears, differences in X-over freqency that i had noticed I was attributing to the power that I was using with each band.
But that said; perhaps there have been different manufacturing batches with somewwhat of a quality control issue

jeff mai · 18th August 2007, 07:24 AM

I agree it's tough to hear what's wrong - until it's corrected! I set each channel's dial set to the same position as best as I could at what I thought would be 500Hz. When I measured one channel was actually crossed at 700Hz and the other was crossed at nearly 900Hz! I measured the unit alone with a laptop soundcard - no amps in line to mess things up.

If you have the patience to measure when you want to change something, this isn't a problem. The unit performs fine when properly configured by measurement. I agree that my sample may have been out of spec, but the tolerances of typical cheap pots aren't fantastic so this could be typical.

OzMikeH · 20th August 2007, 11:48 PM

I decided it's not for me. I downloaded the manual, the delay adjust is for the low channel only. I want time adjustment in the highs as well. I'm doubtful the adjustment is fine enough for 10kHz wavelengths, it's 41 steps from zero to 2ms.

I'll measure my speakers then build a line level 24dB/oct XO to suit, Delay circuit (if required) can be incorporated in the XO box at the same time. I may even stick a T amp in there for the tweeters.

rockermtnman · 2nd November 2007, 01:09 PM

Jeff, Do you still have your movie theater speakers?
-Manny

DonoMan · 6th January 2008, 05:33 PM

I have the CX3400 and it's horribly noisy. I have to keep the input gain knobs down a lot and send it a higher level signal to compensate to get an acceptable SNR. It's not my receiver or amp.

thinking of replacing some op amps. Don't feel like taking it apart until I know what I'm doing. Anyone do this, or at least got pics of its guts?

17th August 2007, 07:26 AM	#11
Moondog55 Dilletante, tinkerer and beggathoner supreme diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	try these links http://www.allansmusic.com.au/Product.aspx?p=53281 http://www.allansmusic.com.au/Product.aspx?p=53890 Still reasonably cheap Ted __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

18th August 2007, 06:16 AM	#13
Moondog55 Dilletante, tinkerer and beggathoner supreme diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	Hi Jeff, must say that that isn't audible to my aging ears, differences in X-over freqency that i had noticed I was attributing to the power that I was using with each band. But that said; perhaps there have been different manufacturing batches with somewwhat of a quality control issue __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

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18th August 2007, 03:19 AM	#12
jeff mai diyAudio Member Join Date: Aug 2002 Location: Melbourne	The unit I borrowed had minor (but significant) level discrepancies when both channels were set to the same level by the dial markings: 2-3db differences in some positions. Additionally, the crossover frequencies between the two channels were as much as 25% different when the dials were set to the same position. This isn't necessarily easy to hear in a multichannel system until you fix the issue. These crossovers are great for what they are, but if I were leaving one in my system long term or evaluating other system components or changes, the problems need attention.

18th August 2007, 07:24 AM	#14
jeff mai diyAudio Member Join Date: Aug 2002 Location: Melbourne	I agree it's tough to hear what's wrong - until it's corrected! I set each channel's dial set to the same position as best as I could at what I thought would be 500Hz. When I measured one channel was actually crossed at 700Hz and the other was crossed at nearly 900Hz! I measured the unit alone with a laptop soundcard - no amps in line to mess things up. If you have the patience to measure when you want to change something, this isn't a problem. The unit performs fine when properly configured by measurement. I agree that my sample may have been out of spec, but the tolerances of typical cheap pots aren't fantastic so this could be typical.

20th August 2007, 11:48 PM	#15
OzMikeH diyAudio Member Join Date: Mar 2007	I decided it's not for me. I downloaded the manual, the delay adjust is for the low channel only. I want time adjustment in the highs as well. I'm doubtful the adjustment is fine enough for 10kHz wavelengths, it's 41 steps from zero to 2ms. I'll measure my speakers then build a line level 24dB/oct XO to suit, Delay circuit (if required) can be incorporated in the XO box at the same time. I may even stick a T amp in there for the tweeters.

2nd November 2007, 01:09 PM	#16
rockermtnman diyAudio Member Join Date: Oct 2007	Jeff, Do you still have your movie theater speakers? -Manny

6th January 2008, 05:33 PM	#17
DonoMan diyAudio Member Join Date: Feb 2005 Location: Massachusetts	I have the CX3400 and it's horribly noisy. I have to keep the input gain knobs down a lot and send it a higher level signal to compensate to get an acceptable SNR. It's not my receiver or amp. thinking of replacing some op amps. Don't feel like taking it apart until I know what I'm doing. Anyone do this, or at least got pics of its guts?