contrabass Posted October 10, 2009 Share Posted October 10, 2009 Hi All, I'm looking for advice on a new power amp for my double bass rig. At the moment I have a Headway EDB1 preamp + Crown XLS 202 power amp + Schroeder mini 12L cab. The theory was to let the preamp deal with EQ then beef it up with a power amp. This all seems to be ok at low volume but I'm lacking power in louder situations. [url="http://www.crownaudio.com/amp_htm/xls.htm"]http://www.crownaudio.com/amp_htm/xls.htm[/url] [url="http://www.headwaymusicaudio.com/product_edb1_acoustic_preamp.php"]http://www.headwaymusicaudio.com/product_e...stic_preamp.php[/url] [url="http://www.schroedercabinets.com"]http://www.schroedercabinets.com[/url] thanks in advance Quote Link to comment Share on other sites More sharing options...
samej Posted October 13, 2009 Share Posted October 13, 2009 I would guess the preamp doesn't provide enough output signal to fully drive the power amp. Despite the name, many instrument preamps aren't designed to be plugged directly into a power amp requiring a pro-audio level signal. Which is pretty annoying! If you have access to a mixer you could put that between the pre and power amps and set the level on that to provide a full signal to the power amp (0dB on the meter I think) and see if that makes a difference. If so then that is the problem. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted October 13, 2009 Share Posted October 13, 2009 If you're not doing so already, try bridging the XLS202 to give you another 6dB gain. Alex Quote Link to comment Share on other sites More sharing options...
contrabass Posted October 13, 2009 Author Share Posted October 13, 2009 To quote the headway website "Outputs are via a balanced XLR D.I. out and a line out Jack" I am using the xlr into the power amp - I don't think that is the problem - It distorts if I increase the preamp gain. I experimented some more at a couple of gigs over the weekend - I got better results (a bit more volume) by rolling off the bottom end. Maybe I need a high pass filter? Also, I have been using it bridged mode. I was expecting a lot more power - the spec is 600w at 8ohm bridged. Quote Link to comment Share on other sites More sharing options...
samej Posted October 13, 2009 Share Posted October 13, 2009 The preamp output specs are: OUTPUTS • Line Output: Nominal 0.5V RMS @ 100 Ohms • Balanced Output via XLR : Nominal 1.0V RMS @100 Ohms Electronically Balanced And the XLS input sensitivity is 1.25V for full power. I suspect that 0.25V can make quite a difference, but I don't really know. The distortion will almost certainly be the preamp not the power amp. You can happily send an underpowered distorted signal to the power amp. Maybe someone else will be along with a better answer soon.. 600W should be plenty. Quote Link to comment Share on other sites More sharing options...
contrabass Posted October 14, 2009 Author Share Posted October 14, 2009 thanks samej - I hadn't looked that far into the specs. It sounds possible that the 0.25V would make a difference although I'm not sure what to do about it. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted October 14, 2009 Share Posted October 14, 2009 Try the 1/4" line-out - many XLRs are set to mic level which is a lot quieter than line level. Alex Quote Link to comment Share on other sites More sharing options...
contrabass Posted October 14, 2009 Author Share Posted October 14, 2009 I will - thanks Alex. Just need to get the right lead. Quote Link to comment Share on other sites More sharing options...
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