Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

boosting power handling on henry the 8x8?

Discussion in 'Amps and Cabs [BG]' started by jasonbraatz, Dec 8, 2001.


  1. jasonbraatz

    jasonbraatz

    Oct 18, 2000
    Oakland, CA
    hey, i may be getting a henry soon, finally, and i have a question. i love how it sounds, but i'd really like to be able to use it as my only cab, running my dcm bridged into it @ 1000 watts. i only probably need about 5-600 watts to be heard on stage, but i'd really dig that much headroom.

    is there any way i could put speakers with higher power handling capability in there? are there even any that would work/sound right? or are the power ratings conservative on the henry, and i'd be ok as it is running bridged? (lets see, for an example of how much volume...on my last gig, since my triad is still out of commission i ran bridged into an 8 ohm peavey 4x10 (700 watts) and was loud enough but i was hitting the clip light on the amp every once in a while, and the speaker was farting and jumping around like nothin else)


    also - does the new chrome grill work as a replacement for the old grille? i'd really like to switch that if i get it.



    jason
     
  2. BigBohn

    BigBohn

    Sep 29, 2001
    WPB, Florida
    I would just think the most obvious way to up the power handling is get new speakers up in there, but that changes tone and lots of variables that make what the cabinet is. I don't know many companies that use the 8" drivers except Bag End and SWR.

    About the chrome grille, that would be cool if they sold it separately because I would definetely buy it and put it on an Eden 410XLT, well maybe not, but it might look cool. I'm not sure if you could order that specific part, but call SWR and they'd gladly answer, I would think.
     
  3. jasonbraatz

    jasonbraatz

    Oct 18, 2000
    Oakland, CA
    well...so far i've found that eminence and carvin make 8" bass speakers. the henry goes down to like 35hz...does that mean i would need to put speakers that go down that far in there too?


    jason
     
  4. In order to get the max output from a speaker cab you have to fall back on a soundman's rule of thumb.... the power amp's RMS output should be twice that of the speaker cab's RMS rating. The Henry is rated at 480 watts RMS at 4 ohms so if your amp is putting out 1000 watts RMS into 4 ohms you're sitting right where you want to be.

    The reason you were clipping into the Peavey was because the Peavey cab is 8 ohms, 700 RMS. To power that cab properly your amp would have to put out 1400 watts RMS into an 8 ohm load. You were under powered with that cab and pushing the amp into clipping. You would have the same problem if you modified the Henry to handle more power. You don't have enough amp to drive more than a 500 watt cab without clipping.
     
  5. I'm an old soundman and I don't use that rule of thumb...:D. But you are pretty much correct that using a 1000 watt amp on a cab rated for 500 watts isn't much of a problem. The cab will take 1000 watt peaks without too much problem. However, if you're driving the amp really hard, ie more than just the occasional clip light, you would stand to damage the speakers.
    About the underpowering thing, well, there isn't really any such thing. The reason the amp was clipping has nothing to do with how much power the cab can take. If the same cab could only take 200 Watts, he'd still be clipping the amp to get to the same volume out of it (just doing more damage to the speakers).

    I'd suggest that if you were only occasionaly clipping the amp into an 8ohm 4x10, you'll be fine with the Henry. You'll get more clean power out of the amp at 4 ohms and the benefits of 4 more drivers. As for replacing the speakers in the Henry, I think that it would be more trouble than it's worth and would very likely make the cabinet sound worse and be less efficient. The cab is designed and tuned with the Theile-Small parameters of the original celestions in mind, so unless you could find 8's with better power handling that had very close to the same T-S specs you'd really be playing with fire. For example, last week, the owner of a bar I mix in occasionally replaced a 15 in a JBL W-Series cabinet with a 15 that could take more power but had a much lower resonant frequency than the drivers that are supposed to go in them. This 15 just about destroyed the cabinet because it was producing a lot of extra LF. It also just about destroyed itself because the box couldn't provide enough damping at the resonant frequency to damp the excursion of the cone. Bottom line: it's risky to put speakers in a cabinet if they aren't matched to it.
     
  6. Why would you want to change the classic Henry grill to the ugly Chrome grill? To make people think you own a SWR Sound cab rather then a SWR Engineering cab?

    It's super cool to remove the SWR logo from the diamond grill.

    The classic & beautiful 'diamond' Henry 8x8 grill is bent about 1/2 inch as a stand off. The Chrome grill has wood trim as the 1/2 stand off.

    SWR will void you warranty (if yours is still active) if more then 500 watts is applied to the Henry. I've seen the Celestion voice coils roast when powered by a SWR 750. I've had all eight of my 8" drivers replaced because of warped voice coils from over powering. You won't really get THAT much volume increase from 500 watts to 1,000.

    But... to each their own.:cool:

    Classic SWR Engineering Beauty
    [​IMG]
     
  7. That's the point. If you're driving a 500 watt cab with a 1000 watts, the amp should be able to give all the cab can take without the clip light ever comming on. It's not too much power that blows speakers, it's pushing an amp that's too small (underpowered) so hard that it clips and it's a clipped signal which eats speakers alive.

    The speakers see a clipped signal as DC current and and during the time period the speakers are receiving a clipped signal they move neither in nor out and they produce no sound, they just sit in a locked postition and generate heat which is what fries the voice coils and is what accounts for the "farting" sound you hear. You will kill a 500 watt cab faster with a 100 watt head than you ever will with a 1000 watt head and that's a fact. If the clip light is comming on then you're feeding DC current to the speakers and pushing your amp too hard. The answer is you need more amp, not more powerful speakers.
     
  8. EString

    EString

    Nov 20, 2000
    Los Altos, CA
  9. BigBohn

    BigBohn

    Sep 29, 2001
    WPB, Florida
    Not necessarily. The speakers can go down to whatever ever frequency they go to, yet SWR rated the actual output frequency of the cab being 35Hz. I would assume the tuning frequency of the cabinet alone would be around the same frequency, so any driver you install in it will still get a similar low end response, not exact because clearly the cab was designed for those Celestions.

    If you know the technique of soldering and electricity, you should have the basic understanding of doing this whole procedure yourself. If you know you're not this, then get a pro to do it. Better be safe than sorry, once you plug up your amp to it and the speakers blow, as do your ears by the sound the speakers make.
     
  10. Chrome = Truck Bumper
     
  11. Trust me, it's too much power that blows speakers. That and driver fatigue. You'd need to drive an amp a looong way into clipping to see anything like DC at the speaker. Most amps clip lights come on at 1-2% THD, so that's a pretty gentle squaring off of the waveform. If distortion is audible, the amp is probably being driven many dB into clipping and actually producing way more than its rated clean power. Just think about it. If you ran a .1 watt amplifier massively overdriven so that the distortion was well audible and ran it into a 500 Watt speaker, would you blow the speaker? Nope. The 500 watt speaker would easily dissipate the power. Guitar players do it all the time, a distorted guitar sound has loads of clipped off waveforms, but guitarists don't blow speaker after speaker after speaker. Clipping amps does blow speakers but it ain't because of the distortion, except for extreme cases. I've never seen an amp clipped so hard that the speakers didn't move and produced no sound. I suspect the amp would cak pretty rapidly if it was driven that hard. True DC, like the high voltage DC you get when a power transistor in an amp shorts, will blow speakers, but we're talking in the range of 100 volts at 10 Amps here.

    The upshot is that if you have a 100 watt amp and you don't have to drive it hard you could hook it up to a cab that can take any amount of power greater than 100 watts without ever being concerned about blowing the speakers. If you're clipping the amp all the time, then yes, you need more power, but there's nothing intrinsically wrong with powering a cab with an amp that's less powerful than the cab's rated power, it only becomes a problem if the amp's not loud enough.

    I'll say it again, blindly shoving replacement speakers into a cab is not a good idea, unless they have very similar specs to the originals. So if you think the Henry can't take enough power, get something else. Or two Henrys:D
     
  12. This is simply not true.
     
  13. Thank you. :D
     
  14. If the the amp is clipping enough to make the speaker start farting, then it's enough DC to lock the cone into position for the duration of the clip and destroy it. A 1 watt amp can't blow a 500 watt cab because it doesn't put out the current to get the voice coil hot enough, but a 100 watt amp does. I have a soldering iron that melts metal with only 100 watts.

    My Crest V1100 in bridged mode puts out at peak 1400 watts and 158 volts across the speaker termainals, if that starts clipping you can bet it'll eat through a voice coil in short order regardless of the speaker's power rating.

    OK, let's use your example and say you're driving a 1000 watt amp at max but it's clipping only 2% of the time. 2% of 1000 is 20, that means 20 watts of power is being converted directly into heat by the voice coil and that twenty watts of heat is over and above it's normal operating conditions. That's just when the clipping light just starts to come on.

    Guitar players get away with it because they use tube amplifiers. Tube amplifiers don't produce DC current when they clip. Guitarists using solid state amps, such as Line 6, are suseptable to the same clipping problems as anybody else using a solid state amp.
     
  15. Tubes effectively clip the same as solid state devices except that they produce different harmonics. Are you saying that hard clipped tubes don't produce square waves? Put a tube amp on a scope and see for yourself.

    I've read that article and many others regarding this subject. I'll just say that the world of sound reinforcement and/or audiophile hifi is full of half truths and pseudoscience. I'm basing my point of view on a large volume of material I've read and from conversations I've had with speaker and amplifier engineers as well as a considerable amount of experience. If what you're saying was true, the act of reproducing a distorted electric guitar in a PA system would inevitably blow up the speakers. I don't think so.;)
     
  16. Davemell0

    Davemell0

    Nov 19, 2001
    SW Virginia
    ok you're getting too wound up in your arguement to give any really practical advice. you might as well be argueing about whether solid state amps can sound good. So just for the fun of it, I'll throw in my opinion too. first, I wouldn't reccommend replacing the speakers in your cab, if a cab is incapable of producing the volume you need, you should just buy a new cab. Speaker cabinets are tuned to work best with a certain speaker, and it would take a lot or research to find replacement speakers that would give you a better preformance level.
    Also everyone posting to this topic is right. overpowering a speaker will blow it up, and driving an amp into clipping, especially a solid state amp, puts more strain on the speaker, will you blow the speaker right away? maybe, maybe not, but with a solid state amp it probably won't sound good. and it means you run the risk of damaging them.
    So use the 1000 watt power amp with the Henry 8x8, but remember not to turn it up all the way, if you don't turn it up so much that its distorting the speakers it won't blow, no matter how powerful your amp is. I've found that I can seperate the sound of speaker distortion from the sound of amp distortion, its really not that hard, so if you hear your speakers distorting, turn your amp down, its simple, if this doesn't give you enough volume, then I'd suggest getting another cabinet.
     
  17. captainpabst

    captainpabst

    Mar 18, 2001
    Tennessee
    i have a henry with a bass 750. i haven't had any problems, but i also haven't played the amp with the clip light constantly on either. i took swr's advice in the owner's manual - adjust the gain to the point that the clip light barely flashes when you play your loudest note (thumb slap, for example). then adjust the volume to your liking. i always use the limiter, and i'm afraid to turn the volume past six or seven because i don't get much more apparent volume, just more cone movement, and i don't like that. so i think as long as you're sensible about it, it'll be fine bridging 1000w into the henry. but why not try running the henry off of one side of them amp and your goliath jr. off of the other? not much more to haul to the gig, you could use the g. jr. as a monitor to hear yourself better, and wouldn't run the risk of frying the henry with too much current - just keep the amp below clipping and there shouldn't be any danger.

    oddly enuf, i've found that if i run the bass 750 at 2.67 ohms (its rated minimum impedance - henry (4 ohm) plus another 8 ohm cab) vs. 4 ohms (just henry), keeping all settings the same, the clip light hardly ever comes on and the limiter is alot less active at 2.67. plus adding another cab gives me all the volume i could possibly ever want - it's nearly over the line. bridging the 1000w into two 8 ohm cabs may be the answer, even if you don't want to haul around two cabs. i dunno. good luck. and btw - i dig the phat phunkton album! :cool:
     
  18. Sorry, I do have to take exception to this....
    I'll challenge anyone to prove that a solid state amp driven into clipping is more harmful to speakers than a tube amp driven into clipping. This simply isn't true. The two different types of amps do sound different when driven beyond their linear range, but it's generally believed that the differences are based on differences in harmonic content.

    Again, speakers only get fried voice coils when they are not capable of dissipating the energy put into them. Even if you put pure DC into them. If the driver can dissipate the energy it won't fail. Incidentally, 90% of the speaker failures I've seen (and I've seen lots) have been due to overexcursion, not melted voice coils. Stuff like the basket seperated from the surround, voice coil blown out of the gap, etc. The only cone drivers I've seen with melted voice coils had amps short an output device and send 100 odd volts DC through them. Compression drivers see a bit more heat failure, because they just can't dissipate that much power. You'll fry a voice coil by overpowering it with clean power as well. I will admit that at a certain power level (say 1000 watts, for example) a clipped wave form will do more damage than a clean one. That is assuming the speaker can't dissipate 1000W. There is some truth in what Mudbass is saying, he's just missing some of the subtlties.
     
  19. leper

    leper

    Jun 21, 2001
    seriously, the easiest way to boost the power handling is to simply buy another...twice the power handling X twice the speakers = 4 times as good :)