Members jwu Posted October 9, 2008 Members Share Posted October 9, 2008 Hi all, When pairing a bass head with cabs, how do I figure out the power capacities to look for? More specifically, I have a SWR SM-400S, which puts out 250W into 16 ohms, 400W into 8 ohms, and 500W into 4 ohms. I'm planning on running it into a SWR Son of Bertha, which is rated at 350 watts at 8 ohms. Would the amp be overpowering the cab, or is it designed to handle the excess wattage? Or would I be better off running into a Goliath 410, rated at 700W at 4 ohms? Also, would it be safe to run another cabinet in parallel? How would I figure out the effective ohms/wattage of the cabinets? For example, if I wanted to run another 2x10 cab together with the Son of Bertha, would I want to get another 8-ohm cabinet? And if so, what wattage capacity should I be looking for? Thanks! Link to comment Share on other sites More sharing options...
Members JeffBass Posted October 9, 2008 Members Share Posted October 9, 2008 You could use either cab just as long as you don't crank the Son of Bertha too high and bang away with excessive noise. If you start hearing distortion, back off the volume or even adjust the EQ reduce the noise. That being said I would likely go with the 410 standalone over the 1x15. Depends on what you like. If you run both you have to make sure your amp can run safely below 4 ohms, otherwise you have to pick one cab. Link to comment Share on other sites More sharing options...
Members xOriginalNinjax Posted October 9, 2008 Members Share Posted October 9, 2008 The SM-400S with the Bertha should be just fine. Unless you're playing with the volume and gain all the way up... Link to comment Share on other sites More sharing options...
Members jwu Posted October 9, 2008 Author Members Share Posted October 9, 2008 Thanks for the responses! I think I'll go with the Goliath 4x10. I really like how the 10-inch speakers sound in the Redhead, and don't think I'll be disappointed in the Goliath, either. Link to comment Share on other sites More sharing options...
Members JeffBass Posted October 9, 2008 Members Share Posted October 9, 2008 I actually like the way a single 15" cab sounds when rehearsing or playing small gigs because it sits in well with the band. The 410 will give you more sound in louder situations though. You may find yourself using either cab, depending on the situation. Link to comment Share on other sites More sharing options...
Members WynnD Posted October 9, 2008 Members Share Posted October 9, 2008 If 400 watts isn't enough power for a club, your band is too loud. I'm still playing small to medium sized clubs with less than 150 watts on bass. Link to comment Share on other sites More sharing options...
Members JeffBass Posted October 9, 2008 Members Share Posted October 9, 2008 If 400 watts isn't enough power for a club, your band is too loud. I'm still playing small to medium sized clubs with less than 150 watts on bass. It's not the band as much as some clubs are so loud that you would never hear yourself with 150w, single cab amp. Some clubs will compensate with good monitor coverage but others won't. It's a matter of being prepared for those types of situations. Link to comment Share on other sites More sharing options...
Members Crescent Seven Posted October 9, 2008 Members Share Posted October 9, 2008 A good way to think about it is, your volume knob is the power output knob. As long as you're not cranking it to where the speakers are distorting, you won't have an issue. Power output also increases with spikes in dynamics, and with lower frequency notes, so if you're playing soft and then hammer a note really hard, or you pound the B string, it will increase the amount of power the amp is pushing for that particular note. A 1000w amp turned up to 2 will only be putting out a fraction of that 1000w, so as long as you're reasonable with the volume and bass control on the EQ, you won't have a problem. Expect someone to come and clarify this post a little bit, I don't know if I explained it well... C7 Link to comment Share on other sites More sharing options...
Members jwu Posted October 9, 2008 Author Members Share Posted October 9, 2008 My main concern was about running an amp into a higher-rated cab, and the concern isn't about having enough volume, but more about matching the cab and head. For example, if I run a 400-watt head into a 700-watt cab, what are the downsides? I always thought that the higher-rated speaker would "suck" more power, making the amp work harder than it needs to, even at lower volumes. Fortunately for me, the Goliath II is rated at 500w at 8ohm, so it's close enough to the SM-400S's 400w at 8ohms that I don't think I need to worry. And besides, I won't be pushing the amp too hard anyways. Link to comment Share on other sites More sharing options...
Members WynnD Posted October 10, 2008 Members Share Posted October 10, 2008 Too much power is always OK. It only becomes a problem with too much ego in the mix. In my own experience, it wasn't my playing that was a problem. It was when I lent my amp to someone else that having more head than speakers became a problem. (Some people just don't know when to stop turning up.) I'm with the others. That amp/cab combination isn't a problem if you listen for trouble. It would be a problem if you loan it to someone else. Good luck. Link to comment Share on other sites More sharing options...
Moderators Kindness Posted October 10, 2008 Moderators Share Posted October 10, 2008 I always thought that the higher-rated speaker would "suck" more power, making the amp work harder than it needs to, even at lower volumes. That's a common misconception. However, the thermal rating and/or displacement limit of a cabinet is independent from the sensitivity (i.e., efficiency) of the cabinet. Have you looked in the FAQ at Agedhorse's post? It is linked in my signature as well. Link to comment Share on other sites More sharing options...
Moderators Kindness Posted October 10, 2008 Moderators Share Posted October 10, 2008 A good way to think about it is, your volume knob is the power output knob. As long as you're not cranking it to where the speakers are distorting, you won't have an issue. Power output also increases with spikes in dynamics, and with lower frequency notes, so if you're playing soft and then hammer a note really hard, or you pound the B string, it will increase the amount of power the amp is pushing for that particular note. A 1000w amp turned up to 2 will only be putting out a fraction of that 1000w, so as long as you're reasonable with the volume and bass control on the EQ, you won't have a problem. Expect someone to come and clarify this post a little bit, I don't know if I explained it well... C7 This is fine except for one clarification. No matter where you have your volume knob set, it is possible for an amp to put out its full power if you have a strong enough signal coming into the input. For example, an amp on 2 with a passive bass plugged into it is never going to be an issue. But an amp on 2 with a bass into a booster pedal, into a preamp, into the front end of the amp might be a problem. In other words, the volume knob isn't acting as a limiter on the output section. Link to comment Share on other sites More sharing options...
Members jwu Posted October 14, 2008 Author Members Share Posted October 14, 2008 Thanks for dispelling the myths.... and the pointer to the FAQ. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted October 14, 2008 CMS Author Share Posted October 14, 2008 Only 50w above the speaker capacity is no problem at all. You'll never get anywhere near the maximum rated power on anything remotely approaching a continuous basis while playing bass. Link to comment Share on other sites More sharing options...
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