Watts vs Decibels is it worth it?

Discussion in 'Amps and Cabs [BG]' started by Moordoom, Nov 24, 2016.

  1. I'm surprised the lawyers didn't make them post it on the front of the cab where it belongs! (along with a bleeding ear symbol)

    I guess my stickers were taken off by the time I purchased them.
  2. hbarcat

    hbarcat Supporting Member

    Aug 24, 2006
    Rochelle, Illinois

    I agree 100%. If the guitarist's stage volume is too loud, then everything else I said about the bass and drums and vocals and PA is meaningless.

    Personally, I flat out refuse to play in a band that can't keep its stage volume under control. I use an SPL meter to make sure what we're doing on stage and in the room with my PA is quantified and therefore repeatable and reliable.

    I did say, in my 1st post, that the guitarist needs to turn way down. I was very clear about that being essential to the overall plan of getting proper stage volume and balance as well as controlling what goes into the PA.

    Someone said I was giving BAD advice. I repeat: this is accepted as best practice. The professionals do it this way for a reason.

    Question to the OP - Can you get your guitar player to turn his volume down to a reasonable level? If not, why? Is this a type of metal band where excessive stage volume is part of the image?

    If so, then my advice is totally different. You should get a monster amp that puts out 2,000 watts and upgrade your cabs to ultra duty drivers that can reliably pound out high volume low frequencies all night without failure. Wear hearing protection and also accept that your sound is going to be more loud than good.
    Last edited: Nov 26, 2016
  3. xk49w

    xk49w Supporting Member

    Apr 13, 2008
    That's good. You also stated the band has an acoustic instrument through the PA. I don't see how more bass volume will help that instrument get heard. As others have stated, to cut through add mids, maybe roll off the lows a bit. You could also add a dirt pedal, a Rusty Box, a Darkglass, something that can give you some tonal edge.
  4. BadExample


    Jan 21, 2016
    I don't think it' been asked or stated, but what model is the pair of 4x10's?

    The current BR handles 800 watts and the BRX 1200 watts. A pair of either would handle a very powerful amp.

    If you have older carvin cabs they could be rated differently. If not labeled check the carvin museum to identify and maybe find specs. Manuals with specs are also on the carvin website if you know the model.

    The current cabs are well received by those that own them and the BRX models are known for a hellofalota deep bass.

    Some speakers seem to want a certain amount of power before they wake up. These may be just a bit "underpowered" with your current amp. Thats not to say its harmful, but theres a very good chance they are operating well under their potential output. If they are not current BR/BRX and cant "handle" 1000 watts for the pair (500 Watts each), and you feel uneasy about the higher power several have said you need, go to the Peavy website and in the faqs there is a good paper on amp selection.

    From there take a look at the specs on some amps to see what puts you in the ballpark. You want to look at 4ohm output for one cab and 2 ohm output for 2 cabs.

    I would look at the Mesa D800, Carvin BX700 and BX1500/1600 (about the same thing).

    If you have trouble finding the stuff I mention, I can help when I'm not on my dumbphone.

    If you need help to ID the cabs post up a good clear pic of the front and a closeup of the dish and labels on back.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    As I have said before, it is essential to understand how the speaker cabinets are rated... ie. what units are used. For bass guitar, I tend to recommend matching the RMS power rating of the amp to the RMS power rating of the speaker unless the player has VERY good judgement and self control.

    If the speaker is rated using "program" power, that is usually defined as 2x the RMS power so divide by 2 gets you back to RMS.

    If the speaker is rated at "peak" power, that us usually defined as 4x the RMS power so divide by 4 to get you back to RMS.

    Amps are generally rated using RMS or peak units, in this case peak is NOT the same as peak for speaker ratings. Peak for amps is generally 2x the RMS rating.

    Apply the above correction factors and it will get you to a reasonably safe match. You can go above the 1:1 ratio (in RMS units), but it would be a good idea to understand that failure modes of a speaker and how lifespan can be decreased when operating this way.
    Al Kraft and BadExample like this.
  6. BadExample


    Jan 21, 2016
    Which way to go is somewhat described on the Peavey document, including benefits and drawbacks. I generally like the more power on tap philosophy. While I may lack common sense, judgment and self control, all three kick in pretty good when it comes to expensive audio gear. That is a personal preference... and risk.

    If going the larger amp route, I recommend playing alone, out of the group context, and listening to the quality of the sound. Listen for fart out and play below that level when with the band later where you may not hear it. If you are one to crank up eq or otherwise pump up the signal to the amp, such as with a pedal or built in features of the preamp, that needs to be tested too. The idea is to learn where you can have the master/volume under your playing condition without exceeding mechanical limits. This does not mean you can't exceed the thermal/wattage limits of the voice coil, but most quality speakers can handle normal music up to the point of fart out. If you play a continuous sine wave or even continually strike a low B for a long time at this maximum "safe" level, I have no doubt things will get hot.

    On the other side of the coin, if you go with the safer sized amp and dime all the knobs, it will likely put out more power than what is safe (and sound bad).

    I am no where near Andy's level. Not on the same floor. Probably not even in the same building. I am not arguing what he said, but hopefully augmenting. Andy can scold me and I'll take my lumps as usual :D

    The back dish label on both current BR and BRX are labeled "Continuous."

    Now I'm on a real computer: https://peavey.com/support/technotes/poweramps/HOW_MUCH_POWER.pdf

    The Carvin Museum ID those cabs if you don't already know what you have and you will likely get some more accurate advice on amp wattage.

    This one is interesting too: https://peavey.com/support/technotes/concepts/THE_LOUDSPEAKER_SPEC_SHEET_GAME_2005.pdf
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The first white paper was written by Don Boomer, an old friend of mine from the pro audio world. If you read carefully, he addresses the increased risk within bass guitar applications by qualifying everything based on proper high pass filtering and the potential for mechanical damage. Thermal ratings are not all that useful except that they tend to roughly correspond to the maximum mechanical power handling unless additional measures or investigation is done and understood.

    Bass guitar applications are somewhat unique in that slapping creates dynamics that are purely mechanically limited while heavy compression (including driving a tube amp or tube amp simulated output into limiting/clipping) tends to represent the more thermally limited end of the spectrum. This is why there is no hard and fast rule and why I base my recommendation on approx. the "RMS" rating as it pretty much falls in the middle of the mechanical and thermal limitations under more conditions. I have analyzed a lot of driver failures, including those that I intentionally tested to destruction in order to obtain data for high pass filter algorithms as well as for effective methods on managing output overdrive and simulation conditions. The last thing I want is folks damaging speakers with amps (and/or speakers) that I have designed.

    Also, it should be noted that most of the speaker ratings used consider that the speaker needs to last only 2 hours and can be way off spec. after the end of the testing period. My ratings generally consider a 200 hour "must survive" period, and less than 10% shift in (meaningful) TS parameters. For example, if we were to substitute the more common 2 hour "must survive" time period and less stringent parameter tolerances, the 400 watt Subway 115 might end up at 500 or even 550 watts RMS... yes a more impressive marketing number but not very conservative at all. This is the reason for the (conservative) math used in determining the real world power handling, especially when 5 year transferable warranties are concerned.
    JohnMCA72, Al Kraft and BadExample like this.
  8. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    These are the kind of insights into design philosophy and approach that I wish every company/designer felt comfortable sharing. Of course, I'm guessing that a number of companies would rather use numbers to impress rather than to transparently inform. Impressive numbers can become much less impressive bordering on meaningless unless viewed in the context of actual test conditions including a full disclosure of "test passed" criteria.

    I think threads like this one are especially valuable for helping people become better educated consumers/product users. My own technical background in unrelated areas helps me a bit in noodling through this kind of stuff, but when experts share their perspectives, experience and hard science it becomes obvious how much more is involved than just understanding that Volts push Amps through Ohms. :)
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The tradeoff of being conservative is that some customers will not understand (or even attempt to understand) and go with the more impressive numbers regardless of actual performance... and no amount of education attempt will have any effect on their opinions or beliefs. I have battled with marketing folks about this for most of my career.
    Cirk likes this.
  10. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    That's one reason I chose to spend my life working in government/military aviation and weapons programs where marketing folks are only involved in glossy pictures that show up in magazines/TV ads and "customers" want to a talk to engineers about every last detail.
    agedhorse likes this.
  11. BadExample


    Jan 21, 2016
    Yah, Don did a good job on that document. If you look at my siggy, it's quoted. He emphasizes the effects of eq/freq more than once in this and other writings. I think it was he who said something like the smile on your equalizer is the amp smiling at the speakers it's about to kill :D
    Al Kraft likes this.
  12. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Don and I participated on another pro audio forum years ago, and he ran a sound company a hundred miles or so south of me before he worked for Peavey, Line 6 (and others). One of the good guys, talks the talk and walks the walk.

    He gave up this rat race maybe 18 months ago and is running a form of rock and roll music fantasy camp:
    Take2 - Rock n Roll Reality | Facebook

    Rumor also has it that he is doing some wireless mic application consulting.
    BadExample likes this.
  13. Ant Illington

    Ant Illington I'm Anthony but I'm only illin' Inactive

    Awesome story! It's surprising that such a much-lauded band would be kept out-of-touch for so long by whoever their handlers/sound-people are! On that note, though, I wonder if it is the nature of the big concert beast, especially the big, LOUD, metal concert beast. The audience demands LOUD (at least much of the audience seems to want it) but with loud, especially in a big room, it seems a big mess comes. I have never been to a hard rock concert in a big venue (including Rush) where I thought the sound was particularly good- sure you recognize the songs and your brain fills in the blanks and you get to see your heroes...

    Yes, in smaller clubs it can work, even if you might have to go to the sound guy and say "hey, can you maybe boost some x. Also, I've seen Anita Baker twice and Rod Stewart twice, both in big venues and the sound was great and even the bass was distinct. But overall not tremendously loud. Is there a correlation between both loud and big and bad sound? All that I do know is I LOVE concert DVD's more than concerts!!!!
  14. StayLow


    Mar 14, 2008

    [Off Main Thread Topic]

    All agreed. In this case there were some egos or power plays involved for quite awhile. Basically sound crew were left to do what they could with what they were given. Then again many pro sound men in metal are blowing out the mix by running ridiculously loud triggered kicks (seems less fashionable now than a few years ago, thankfully) and with a lot of bands down-tuned it just makes one big sludgy reverberating eigentone. Some are bitter lifers. Some have their ears blown and would benefit from just looking at a spectrum analyser.

    The vast majority are cool and capable, but may never think to have a dialogue with the band. Maybe they just really need the gig and would rather not risk raising ire. Maybe once bitten, twice shy? I've seen that first-hand.

    You can do loud and reasonably clean, but it might not be that loud onstage. It might take in-ears and maybe even no amps onstage at all. Or fake ones of course. But that's not "cool" or "metal" in a lot of minds. TSO sounds loud and clean. Not an amp onstage. The recent Dope tour had zero amps onstage and sounded totally pristine. Some dudes just have the ego or childish machismo going on, or maybe just don't think it all through, which isn't exclusive to that genre but it's sadly common in my experience.

    [On Main Thread Topic]

    An acquaintance is sound man for a heavy band that fills large theaters and mid-sized arenas in most of the world. On festivals I've heard bands sound rubbish, then for their set he mans the board and it sounds great, then next band/soundman steps up and it's mud again. In this case the band trusts him to tell them what sound and volume they can get away with onstage without subverting the mix out front. As he put it to me, "We have mutual respect, and they help me to do my job which is to help them sound good. That usually means cutting, not boosting, volume and EQ, both onstage and at the board."

    I've heard very unflattering comments about this guy from bands that don't care enough to check their egos so he doesn't get re-hired by them. In turn he doesn't recommend them for better/bigger gigs and tours. It's that easy. He's mixed a few of my bands and I'm relieved when I find out he's working, especially if he knows the stage or venue and I don't.
    Ant Illington likes this.
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