Amps and cabs

Discussion in 'Amps and Cabs [BG]' started by Yrag, Jun 17, 2022.

  1. Yrag


    Jan 19, 2019
    Hi all. I’m new to the world of Amp heads and cab combos. I want something small and transportable as I’m giging again now after many years off.
    I like the TC electronic bc208 cab and I’ve found two second hand for quite a good deal just local to me. Now they are 200w each. Do I need a 400w head to supply the correct amount of power?
    Please excuse my ignorance. When I was giging back in my youth I got whatever I could afford and at the time and it was a combo fender rumble 100(birthday present), Then onto a 300w valve marshal with two cabs but this was second hand and I bought it all together without really understanding it or the watt range etc.
    I like the look of the Eden head terra nova. Or the bugera veyron. Also the TC electronic bam 200w. My budget isn’t huge.
    So confused of what I could get away with. I really Look forward to some suggestions from the experts. :)
  2. In general, I think it's commonly recommended to have the same or lower powered head than your cab's/cabs' total power handling. So in the case of the two BC208s, yes, 400w or less is generally acceptable.

    Do you also understand Ohms and how that interaction between amps and cabs work? Not trying to be a jerk, just wanting to make sure you are taking that into account as well. :)

    Also: I regularly disregard this "common wisdom" and take massively overpowered amps (now that 800w Class D amps can be small and weigh about 6lbs!) along with a tiny 300w cab for jams/practice. Being wise and careful with volume knobs and low EQ boost is very important here, but as long as you are realistic and paying attention to what's going on with your speaker cab it will all be fine.
    Last edited: Jun 17, 2022
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  3. Yrag


    Jan 19, 2019
    no not really. I was under the impression that the 200w TC electronic would work for two 8 ohm cabs (200w) each.
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  4. Barry Vestal

    Barry Vestal

    Nov 24, 2015
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  5. Yes, your given combination should be fine in theory. However, it's good to have an understanding of WHY that is, and the knowledge to weigh other options as you might start adding/swapping cabs of potentially different ohm ratings.

    The cabs you are talking about are 8 ohm cabs, so two of those plugged in to an amp that can tun at 4 ohms is fine. But if you get two 4 ohm cabs to use with that same 4 ohm head, you WILL fry it.

    Here's a crash course: Ohms FAQ
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  6. spatters


    Mar 25, 2002
    Quick Musician's Guide To Ohms:

    If you have multiple cabs, divide the ohms by the number of cabs.
    8 ohm cabinets / 2 cabinets = 4 ohms.
    It's nearly impossible to find an amplifier that won't drive 4 ohms.

    Where people run into trouble is when they buy two 4 ohm cabinets.
    4 ohm cabinets / 2 cabinets = 2 ohms.
    Most amplifiers WILL NOT drive 2 ohms.
    They might work at low volume, but you're likely to blow something up if you crank it up.

    Cabinets that have two drivers in them, like 2x10, 2x12, and 2x15, are most likely to be 4 ohm.
    Only buy 4 ohm cabinets if you're absolutely sure you will never use more than one of them at a time, or if you own an amp that you know can drive a 2 ohm load.

    (Yes, this is an oversimplification! Cabinets don't always have the same ohm rating...but then it's usually a bad idea to mix and match them. It's possible to connect cabs in serial, instead of parallel, with the correct cables. And output impedance can be more complicated with tube amps that have impedance selectors, especially when via normalling jacks. However, for 90%+ of people, this simple rule answers their questions.)
  7. Yrag


    Jan 19, 2019
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  8. Pulverizor


    Jun 14, 2018
    New Zealand
    Buy as much power as you can afford mate, you might need to upgrade those cabs when you get super popular ;)
  9. Rip Van Dan

    Rip Van Dan DNA Endorsing Artist Supporting Member

    Feb 2, 2009
    Duvall, WA
    I can tell you about the Eden Terra Nova class D amps because I have one. I bought their TN226 (225-watts rms) because I needed something small and light to run an Eden EX-112 cab for a small venue where we hosted open-mic nights on most Friday nights. I have two other Eden amps, a Nemesis RS400 (400-watts rms into 4Ω), and a WT500/800 (400-watts per channel into 4Ω or 800-watts bridged into 8Ω. I certainly could have used those (and have) with that 112 cab, but when a friend of mine decided to sell his TN-226, he offered me a good price on it and I snagged it. It works fine for small venues but the 500-watt version (TN-501) is a much better and far more versatile choice.

    Both the 225-watt and the 500-watt amps share the exact same preamp and it's a very nice preamp. Sound is very clear, clean and articulate and with a Bass EQ at 30Hz, a semi-parametric (choose your frequency) for the low-mids with another one for the hi-mids, and a Treble control for everything above 2KHz. You can dial in just about any sound you want. It also has an Enhance control that boosts the bass, cuts the low-mids, and boosts the treble. That's nice for bedroom practice at low levels where your ears don't hear the bass and treble as well. However if you turn it up over about 9 o'clock to 9:30 in a group you'll start dialing yourself right out of the mix because the bass owns the low mids and that's what gives your bass definition and presence playing in a group.

    Good news is that is also has a bass boost button, which does add some deeper bass without adding any mud to your sound. another really nice feature that it has is an auto-compressor. When you have it engaged you control the threshold point (where the compressor starts compressing) with the gain knob and the gain-set light will flash when it is compressing.

    Had to use that once when our 5-pc group got too loud in that small brewpub because my power clip light was flashing. Engaged the compressor and turned up the gain to make it engage sooner and it worked wonderfully well, compressing my peaks without killing my dynamics and attack. I was impressed because my big Eden amp has that same feature but it is far harsher and in my opinion good for slap and that's about it. So I never use the feature on my big Eden amp. The TN auto-compressor is very musical and a real plus in my opinion.

    Finally, I was concerned that it wouldn't sound as warm as my big Eden amp which has a tube in the preamp specifically to add warmth to the sound. My Nemesis RS400 does not have the tube and the sound is really good, but it doesn't have that warmth to the sound. I was afraid the TN wouldn't have the warmth but it sounds every bit as warm as my Big Eden amp. So I'm really impressed with it and have no trouble recommending it to you.

    Street price on the Eden TN-501 is usually around $649 new. I did see one the other day down at $499, which is closer to what you would pay for a used one. Weight for that amp is 5.3-lbs. The TN501 often shows up on Reverb so that's worth checking.

    Here's a shot of my small venue set-up using my TN226 into an Eden EX-112 cab. Notice how nicely it fits into a chair! I can put the amp in its shoulder bag over one shoulder, put my gig bag over my other shoulder, grab my bass in one hand and my cab by its handle on the top and carry it all out or in with just one trip...I like that part a lot!

    Last edited: Jun 18, 2022
  10. S.F.Sorrow


    Dec 6, 2014
    200w is a bit on the low side for gigging IMO. Of course it wouldn't be if we were talking about a Hiwatt DR201 but I've never found one of these micro sized amps below 400(ish) watts to give me anywhere near enough power. It will depend a LOT on the cab too of course (but with cabs it's usually a matter of bigger is better..).

    It will also depend on the type of gigs and type of music you're playing but I will strongly advice you to try before buying and preferrably in the context of your band. Amps can sound amazingly powerful when playing alone and still get buried when playing with a full band.

    Maybe look for something used?
  11. Barry Vestal

    Barry Vestal

    Nov 24, 2015
    I use a custom 15 cab(4ohm) with the bam as well as a Markbass Nano and I've never had a problem being heard on a small or big stage...It's nice having two amps that weigh a total of 5 pounds in my gig bag:thumbsup::thumbsup:
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  12. BlueTalon

    BlueTalon Happy Cynic Supporting Member

    Mar 20, 2011
    Inland Northwest
    Endorsing Artist: Turnstyle Switch
    That describes most of us at some point. No need to excuse ignorance. If you like the TC Electronics head you have, go ahead and get the speakers. You may outgrow that rig at some point, but it should get you through practices and small/medium gigs.
  13. el murdoque

    el murdoque

    Mar 10, 2013
    The one thing that you really need to watch out for is impedance.
    Here's the impedance for common cabinet combinations:
    8 Ohms + 8 Ohms = 4 Ohms
    8 Ohms + 4 Ohms = 2,6666667 Ohms
    4 Ohms + 4 Ohms = 2 Ohms

    Solid State heads usually deal with impedance on their own, but they do have a minimum impedance, which is usually printed on the back of the amp, right next to the speaker outlet. Most common is a minimum of 4 ohms.

    In layman's terms: The output of an amp is like a tap, running water. If you match the minimum impedance, the tap is running full, at 100%. If you do double the impedance (one 8 Ohm cab at a min 4 Ohm amp), you attach a hose to the tap and give it a squeeze. Less water is running, but it's fine.
    If you undercut the minimum load (2 Ohms cabinet at minimum 4 Ohm) you take the tap from the example and increase the water flow to 150%. While this could be possible for a short while, you can be sure that the pipes in the wall will not agree with that treatment for more than a very short while. Something will give. You will need to find a qualified repair person. This will be expensive.

    With tube amps, it's different. In a nutshell, while a SS amp runs fine without a cab, a tube amp does not. You need to attach the right cab to the right outlet at all times.

    Apart from that, you can combine any kind of cabinet with any kind of amplifier, as long as you use your ears and your common sense.
    Put a 5W mini amp on top of a 8x10 1600W cabinet.
    Or put a 4,5kw poweramp on top of a 200W cabinet.
    Both will work. The former holds no danger for anything while in the latter example, the poweramp can easily blow the speaker if you turn it up too much - so you need to use your brain and your ears. Determine the point where the speaker starts to strain and never push past it. Never play such a setup in an environment that might be too loud for the speaker. When you can't hear yourself properly and turn up the amp, you won't hear the farting sounds or the death rattle of your speaker either. As uncle Ben said in Spider Man: "With great power comes great responsibility".

    Power ratings is another issue. Some companies have real engineers in real labs that determine real figures and they get printed on the box.
    Some companies figure that bigger numbers are better numbers and let the marketing department have their way with the people in the lab and come up with numbers on the box that are more a product of happy rainbow wishful thinking than the product of a sober reading of the instruments.
    Happy wishful company has an amp that does 1000W and a cab that can take 1200W and these should be a good fit.
    Sober engineer company has an amp that puts out 500W and a cab that can take 600W and these should also be a good fit.

    Now what is entirely in the realm of the possible is that when you hook up the sober engineering company 500W amp head to the happy wishful company 1200W cabinet and crank it, the speakers get ripped to shreds with your first low note - because happy wishful company arrived at their numbers by looking at the voice coil, which melts at 600W and decided that that means 600W Program and Peak is double Program, so they print 1200 on the box.
    Meanwhile, over at the Sober Engineer office, measurements show that the amp puts out different wattages under different circumstances, but it's safe to say that it manages a little more than 500 in any scenario, so they do the opposite and print 500 on the box. In a good scenario, the amplifier does a little more than 600 watts and that's more than enough to kill the happy speaker because a speaker usually dies from mechanical over excursion long before the voice coil melts and the real limit of the happy speaker is closer to 400 Watts.
    So it is entirely possible that a real world 500 Watts amp kills a real world cabinet that is rated at more than twice than that - you just have to pick the right (wrong) companies to mix.

    Why am I telling this? The numbers printed on the box don't help you unless you know how that particular company arrived at them and what to read into them.

    The concept always stays the same: Unless you have reliable (by that I mean empirical, because trust no one) information that suggests otherwise, assume that your amp will blow your speakers when you dime it and approach your volume goal carefully. If possible, fathom out how much headroom you have. Never turn your head to volume levels in a band mix you have not tested out alone unless you are 100% sure that your gear can take it.

    Note: Turning up the bass knob on any of your EQs means you will increase the Watts pushed through even without touching the volume knob.
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  14. Lots of “wall-o-text” posts, TL; DR.

    I want to impress on OP that cabinet power ratings are a maximum limit: you don’t need to provide the cabinet that much power.

    There is a fallacy, or myth, that you can harm cabinets by “underpowering” them but it is very safely ignored.
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