pantherairsoft Posted October 21, 2011 Share Posted October 21, 2011 Hey folks. Venturing into my 1st pre & power set up. Manuals are rather techy so for those of you using set ups like this I wonder if you can answer the following questions... [b]1...[/b] Preamp has L/R outputs Jack only that can run in either mono or stereo Poweramp has L/R XLR inputs The power amp will be using in 'Bridged Mono' mode... so... I assume I have to connect left & right (to bridge them) rather than just one side of the setup (for regular mono)? Also, would the best connection be a Stereo (TRS) jack to XLR? [b]2...[/b] Power amp I'm looking at is the Crown XTi 1000 - [url="http://www.crownaudio.com/pdf/amps/139548.pdf"]http://www.crownaudi...amps/139548.pdf[/url] - I find much of what it says a little confusing regarding the Speakon outputs to the speaker. Should I be using 2-core, or 4-core cabling? I currently own a number of 2-core cables (but with Neutrik 4-pole plugs on) from both AudioSpares & Piranha. The diagrams seem to imply 2-core is fine, but the text implies it needs to be 4-core. Can anyone better minded in such things help? [b]3...[/b] If I use a pre amp that only has a single output, can the power amp still be used in Bridge mono mode (can you bridge channels without an incoming signal to each?) [b]4...[/b] I've read in places that when running an amp in bridge mono mode you have to specially wire a speakon lead differently at the amp end than the typical wiring that will be at the cab end... Is this correct? Shep Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted October 22, 2011 Author Share Posted October 22, 2011 Thanks for your input. I'm not generating regular bass tones etc... I'm generating huge boosts at 40-50hz similiat to that of PA subs. In fact what I do really is PA related. 1000w plus is totally needed. Boosting 50hz at 3db doubles the power requirement. My EBS amp head is clipping at the output stage causin audible distortion due to the huge 6.5ft wide effects chain which is being fed into it and the huge array of frequencies and sub it's needed to generate. I've spent some time at a local venue and borrowed a power amp to try out a few things and the huge increase in headroom sorts out everything. My application is quite specific and if I was playing 'bass' at any point I'd agree with your statement above, but really I'm a synth player. I do use a 'inefficient' Barefaced cab. This is the only cab which exploits the whole frequency spectrum of what I do as most cabs do not accurately produce 40-50hz in the same way as a PA sub, as most bassists wouldn't want that to muddy their sound - I do. The Big Twin has 2 low passed speakers that love 40hz! It reacts like a PA sub & top in 1 box, which is what I need, not a bass rig. As for buying gear I don't know how to use!? Everyone starts somewhere dude. I know how to use the functions etc, I'm just asking for clarification on some points that are. It accurately covered in most power amp manuals from other players that already use similar setups. Most of my questions have been answered helpfully by PM now anyway and I've used said answers to research further. I'm not in the habit of taking the advice of 'virtual friends' as gospel, but I figure that is kinda the point in a resource like BassChat! Shep Quote Link to comment Share on other sites More sharing options...
alexclaber Posted October 22, 2011 Share Posted October 22, 2011 I'll explain how to set your rack up on Monday. As you know your cab isn't 'very inefficient' like an Acme cab - if it was inefficient you'd have needed to turn your amp up much more than with your EBS neo 2x12". You'd need more than 3x the power to get a stack of two of the new Acme 1x12"s up to the same SPL (although they handle less power, not more, so max SPL would work out about 6dB lower). Few bass cabs exceed 95dB in the lows per 12" and when they do it's thanks to a mid-bass hump so you gain there but lose in the real bass. Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted October 22, 2011 Author Share Posted October 22, 2011 'inefficient' was in ' ' marks as it was a sarcastic comment. I've never used a cab with such immense sensitivity and output. I don't actually consider it remotely inefficient Quote Link to comment Share on other sites More sharing options...
Sjonnie Posted October 22, 2011 Share Posted October 22, 2011 [quote name='pantherairsoft'] Hey folks. Venturing into my 1st pre & power set up. Manuals are rather techy so for those of you using set ups like this I wonder if you can answer the following questions... [b]1...[/b] Preamp has L/R outputs Jack only that can run in either mono or stereo Poweramp has L/R XLR inputs The power amp will be using in 'Bridged Mono' mode... so... I assume I have to connect left & right (to bridge them) rather than just one side of the setup (for regular mono)? Also, would the best connection be a Stereo (TRS) jack to XLR? [/quote] TRS to XLR should do, but for bridged mono you should connect only one channel. Usually on the amp it is indicated what channel to use. The Crown manual you link to mentiones you should use input one for bridged mono. Bridging in this case is done by combining the two channels of the power amplifier. [quote name='pantherairsoft'] [b]2...[/b] Power amp I'm looking at is the Crown XTi 1000 - [url="http://www.crownaudio.com/pdf/amps/139548.pdf"]http://www.crownaudi...amps/139548.pdf[/url] - I find much of what it says a little confusing regarding the Speakon outputs to the speaker. Should I be using 2-core, or 4-core cabling? I currently own a number of 2-core cables (but with Neutrik 4-pole plugs on) from both AudioSpares & Piranha. The diagrams seem to imply 2-core is fine, but the text implies it needs to be 4-core. Can anyone better minded in such things help? [/quote] According to the manual you have a number of options stereo mode; - use two regular two core cables and use both speakons - use one four core cable connected to speakon one. This is still stero mode, so both channels are present on the other side of the cable where they should be connected to separate speakers. This can be convenient if you have biampable speakers. Bridge mode - use one two core cable that is wired specifically for bridge mode. Cores should be connected to 1+ and 2+ [quote name='pantherairsoft'] [b]3...[/b] If I use a pre amp that only has a single output, can the power amp still be used in Bridge mono mode (can you bridge channels without an incoming signal to each?) [/quote] Yes it can. [quote name='pantherairsoft'] [b]4...[/b] I've read in places that when running an amp in bridge mono mode you have to specially wire a speakon lead differently at the amp end than the typical wiring that will be at the cab end... Is this correct? Shep [/quote] Depends on the amp in question. But for the crown this is correct. Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted October 22, 2011 Author Share Posted October 22, 2011 Cheers bud! I'd already had 1,2 & 3 answered and your answers confirm my conclusions... Shep Quote Link to comment Share on other sites More sharing options...
Rich Posted October 22, 2011 Share Posted October 22, 2011 Shep, I used to have this power amp and can highly recommend it. It's a very powerful tool, both in terms of, errm, power and in terms of facilities and features. Most of which I never even got round to trying. If you do want to run it in bridge mono, then yes you'll need to bugger about with specially wired 4-pole speakons. I used to run mine in 2-channel stereo, with the preamp output plugged into both channel inputs. Thus allowing me to use ordinary 2-pole speakons and cable etc. Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted October 22, 2011 Author Share Posted October 22, 2011 I have just finished rewiring a speakon as described. +1/-1 at the cab and, +1/+2 at the amp end. I think my initial confusion was trying to decipher the manuals at 1am in the morning! Thankfully I own 4 Speakon-Speakon leads, all with NL4 connectors so it was easy to change around. Shep Quote Link to comment Share on other sites More sharing options...
alexclaber Posted October 22, 2011 Share Posted October 22, 2011 Make sure you mark which end is which: We use 4-pole at the amp end and 2-pole on the cab end of bridging cables to avoid mistakes! Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted October 22, 2011 Author Share Posted October 22, 2011 [quote name='alexclaber' timestamp='1319309102' post='1412638']Make sure you mark which end is which: We use 4-pole at the amp end and 2-pole on the cab end of bridging cables to avoid mistakes![/quote] Yeah - bright green electrical tape around the cable at the amp end. It'll likely stay connected to the amp end within the amps case anyway. I assume the +1 remains connected to +1 via one core, then the -1 is connected to +2 via the other? One question I haven't found an answer to is that the pre I have been looking at has 2 outputs labeled L and R. Should I just take the TRS-XLR from one side to the channel 1 input of the power amp, or should I use a splitter which is wired 2x TRS - XLR so L & R run into the one channel, or - will it make little difference Shep Quote Link to comment Share on other sites More sharing options...
Lfalex v1.1 Posted October 22, 2011 Share Posted October 22, 2011 Sjonnie's responses reflect my experience with wiring up a QSC to run in bridged mono... Seems that most manufacturers follow the same basic pattern. As for 1kW (or however much) being too much power, I beg to differ. The extra poke (tech term ) offers other benefits beyond perceived loudness gains. More current, headroom and (often) larger damping factors all combine to improve the way in which the power amp controls the behaviour and performance of the cabinet. My QSC power amp hammers my poor old Trace, even with only a Korg Pandora or a cheap mixer used as a pre-amp. Quote Link to comment Share on other sites More sharing options...
Sjonnie Posted October 22, 2011 Share Posted October 22, 2011 [quote name='pantherairsoft' timestamp='1319309314' post='1412641'] Yeah - bright green electrical tape around the cable at the amp end. It'll likely stay connected to the amp end within the amps case anyway. I assume the +1 remains connected to +1 via one core, then the -1 is connected to +2 via the other? One question I haven't found an answer to is that the pre I have been looking at has 2 outputs labeled L and R. Should I just take the TRS-XLR from one side to the channel 1 input of the power amp, or should I use a splitter which is wired 2x TRS - XLR so L & R run into the one channel, or - will it make little difference Shep[/quote] Only if you have a real stereo signal you should use both outputs, but in that case you probably don't want bridge mode. If you really need the two channels use a simple mixer, but never use a 'Y' cable. Look here : http://www.rane.com/note109.html for the details. Quote Link to comment Share on other sites More sharing options...
Sjonnie Posted October 22, 2011 Share Posted October 22, 2011 [quote name='Lfalex v1.1' timestamp='1319310567' post='1412656']Sjonnie's responses reflect my experience with wiring up a QSC to run in bridged mono... Seems that most manufacturers follow the same basic pattern. As for 1kW (or however much) being too much power, I beg to differ. The extra poke (tech term ) offers other benefits beyond perceived loudness gains. More current, headroom and (often) larger damping factors all combine to improve the way in which the power amp controls the behaviour and performance of the cabinet. My QSC power amp hammers my poor old Trace, even with only a Korg Pandora or a cheap mixer used as a pre-amp.[/quote] I use a QSC as well. I run it in stereo mode into two Aguilar 2x12 cabs and love it that I'm capable of adding more bass to my tone without clipping the amp. Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted October 22, 2011 Author Share Posted October 22, 2011 [quote name='Sjonnie' timestamp='1319314458' post='1412719'] Only if you have a real stereo signal you should use both outputs, but in that case you probably don't want bridge mode. If you really need the two channels use a simple mixer, but never use a 'Y' cable. Look here : http://www.rane.com/note109.html for the details. [/quote] Very interesting article. I'm saving that link. Very very interesting. [quote name='Sjonnie' timestamp='1319315071' post='1412724'] I use a QSC as well. I run it in stereo mode into two Aguilar 2x12 cabs and love it that I'm capable of adding more bass to my tone without clipping the amp.[/quote] Exactly why I'm making this move - boosting of 40-50hz and EQ'ing back in what my huge effects chain takes away causes clipping at the output stage. I'm purely after headroom and clarity Quote Link to comment Share on other sites More sharing options...
Soliloquy Posted October 22, 2011 Share Posted October 22, 2011 (edited) [quote name='bass_by_name' timestamp='1319274472' post='1412040']??? Buying lots of expensive gear that you dont know how to use seems to be a recipie for disaster. I am not sure following the advice of virtual friends on the internet will prevent it. You should not need 1,000 watts unless you are using very inefficient cabs like Acme or Barefaced.[/quote] Acme cabs aren't inefficient. They just don't lie about the efficiency of their cabs like most other manufacturers do. I own two Acme's and I've owned pretty much every other cab that it's possible to own. Acme's are no less inefficient in real life than any other. Sorry for side tracking this otherwise interesting thread. I'm putting together my own pre/power amp rig at the moment. Remember that a 1000 watt amp is always a 1000 watt amp, regardless of how you have the volume set. It's still able to produce 1000 watts if it gets a hot enough signal. Edited October 22, 2011 by Soliloquy Quote Link to comment Share on other sites More sharing options...
pantherairsoft Posted November 24, 2011 Author Share Posted November 24, 2011 Been loving this set up - So much umph tot he frequency response and a much richer tone. I've had a few oddities with the behaviour of the clip lights on the power amp but its seems to be playing ball. I'm working to a 'trust' my ears rule The pre amp has taken some time to get 'my' sound back - it's filter section works quite differently to the EBS amps and is not as instinctive, but I've got it down to a tee now! Quote Link to comment Share on other sites More sharing options...
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