If a bass can destroy a guitar cab… what does low f# do to a bass cab?

Discussion in 'Amps and Cabs [BG]' started by TTA, Jul 4, 2022.


  1. TTA

    TTA

    Jun 10, 2021
    If a bass can destroy a guitar cab… what does low f# do to a bass cab?

    If nothing… does porting save cabs? I ask cause i thought i understood why a bass kills a guitar cab/speakers… but maybe i dont fully understand.
     
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Bass speakers are constructed very differently, and cabinets are either ported or sealed. There’s math behind ported and sealed cabinets that govern the performance.
     
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  3. I tried it on July 4th, 2055.

    Next thing I know, I see your post exactly 33 years earlier.

    Looks like it opens a wormhole through time.
     
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  4. TTA

    TTA

    Jun 10, 2021
    long story short they will be fine… just wont make the lower fundamentals?

    Basic terms… What it the difference? Ir is it not basic? Curious to understand. My understanding was that guitar speakers would try to make the movements required for low freq… but they physically could not… so death. When volume and travel got too high.
     
    thunesBARROW likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    A bass cabinet designed with suitable low frequency extension will reproduce the note with a greater proportion of fundamental to harmonics, will do so louder and with (much) higher reliability.
     
  6. Wasnex

    Wasnex

    Dec 25, 2011
    Not necessarily true.

    Info taken from Why are Ampeg SVTs so popular?


    "Here you are with a cab simulation of 215 3015LF vers a 810 B810 modelling.
    System input power equals 800 Watt for each system"
    [​IMG]
    I believe this is intended to be similar to the Ampeg 810E (yellow trace) and fEARflul 1515/66 (white trace).

    Neither cab has usable response to low F# (23.12hz), so there is really no point in feeding them power that low. It just goes to waste. IMHO apply and HPF and save the power to be used in the passband.

    [​IMG]
    As you can see the 810 can handle 800W down to the Low F#, so at least it is not a risk of damage. This not necessarily 100% representative of all sealed designs.

    The pair of 3015LFs run out of excursion just above 30hz with 800W. This is where the trace turns from white to gray. If you feed this design 800W below 30hz, the drivers will be destroyed.

    FYI the "S"-shape of the excursion plot is typical of ported bass cab designs. Excursion begins to increase as the frequency drop below about 500hz. Somewhere below 100hz the excursion starts to decrease. This is because the port is becoming resonant. Port resonance suppresses cone excursion. Maximum suppression occurs at the port tuning frequency (Fb). Also at Fb the port is producing almost all of the sound. As the frequency drops below Fb, system output drops quickly, and excursion increase quickly towards Xmax. It's wise if not essential to apply an HPF to prevent the cab from being fed too much power below its passband.
     
  7. TTA

    TTA

    Jun 10, 2021
    I wont pretend that i understand everything but i think i get it. My understanding is that a bass speaker has the excursion for low f#… it is just pointless due to such low real world output. But you wont fry the speaker for doing it. Except maybe you can if the passband is exceeded.

    Do most bass cabs have hpf’s built in? Or is it trial and error?
     
    Last edited: Jul 4, 2022
    gebass6 likes this.
  8. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Most bass speakers do not reproduce low F# unless they are designed specifically to do so. That would be a very large cabinet and drivers with powerful motors, high moving mass, low Fs and large Xmax. The trade off would be low sensitivity and poor mid extension.
     
  9. Wasnex

    Wasnex

    Dec 25, 2011
    The HPF must be inserted in the signal path to prevent the amp from sending power below the cabs intended cut off.s

    I don't know of any bass cabs that can play down into the 20hz range. I own a couple of homemade EV TL405 setup in step-down mode that have response that low, but they won't produce much volume or take much power that low.
    upload_2022-7-4_22-58-7.png

    Most pro-level subs only have response down to the mid 30hz range.

    Here's a sub that would work for you: DTS10 | Danley Sound Labs
    RATED IMPEDANCE
    4 Ohms

    POWER RATING
    1,000 W continuous
    2,000 W program

    OPERATING FREQUENCY RANGE
    15 Hz- 70 Hz – 3dB
    12 Hz -10dB

    CONTINUOUS OUTPUT
    127 dB SPL

    DIMENSIONS
    59.5 x 44 x 16 inches

    WEIGHT
    285 lbs

    [​IMG]

    127dB is pretty loud, however the Fletcher Munson curve is working against you.

    [​IMG]

    A phon is a measure of perceived loudness. 110 phon = 110dB at 1000hz. Looks like you need 136 dB to produce 110 phon at 20hz.

    You get +6dB if you double the number of subs. This brings you to 133dB with two, and four will give you 139dB. The weight of four is 1140lbs.
     
  10. 12bass

    12bass

    Jan 2, 2003
    Victoria, Canada
    Most ported bass enclosures are tuned well above 23Hz (often close to double that), meaning the drivers will be unloaded when trying to operate at a low F#, so no, they don't have the ability to safely produce sound that low and will fail if pushed. Bass amps often have a HPF filter built in, not cabinets, at least not for the woofers; tweeters in a two/three-way cabinet will have a HPF.
     
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  11. TTA

    TTA

    Jun 10, 2021
    So what you guys are saying is… take my bass and test cabs at the gc before i buy. :-D

    all joking aside no one playing a low F# cares about reproducing the fundamental. That is crazy talk. Never mind cabs ability to produce notes that low… look at the range of hearing of humans. There are people tuning even lower than humans can hear.

    Lucky for us, Bass has always been, and always will be about the mids (harmonics). The low tuning guys are paradoxically cutting actual lows to gain clarity in those muddy frequencies. The listener brain, harmonics (including overdrive), and compressors do the rest.

    Here is my question put another way… why can my f# bass destroy a marshal stack. Do guitar amps not use a hpf? (Note: my favourite bass amp is actually a guitar amp).

    Or am i safe running a f# bass into a guitar amp… into a guitar cab?

    Or are we back to limitations of speaker travel? My guess is a guitar setups hpf saves it from the low stuff… but a bass so easily drives the lower frequency potential of a guitar cab that once you start adding volume… you get a lot of heat… and eventually failure.
     
    Last edited: Jul 5, 2022
  12. devnulljp

    devnulljp

    Oct 13, 2009
    BC, Canada
    Admin on the D*A*M Forum
    Please, the cool kids call it an Einstein-Rosen bridge now
     
  13. Wasnex

    Wasnex

    Dec 25, 2011
    AFAIK the problem with guitar cabs is primarily limited Xmax, so you need to run a fairl agressive HPF on them to keep the safe at high power. But it varies somewhat by cab and driver.

    For example I own a 1960AX/BX full stack loaded with greenbacks. These cabs are rated at 100W each. Thermally I think they are probably fine with 100W, but I wouldn't want to feed one of the 100W of bass. My understanding is one of these cabs would be stressed a bit with a 100W Marshall cranked to the max with guitar.

    The 1960A/B stack is loaded with G12T-75 and rated for 300W. This is the thermal rating. You should be fine cranking bass through one or two of these cabs as long as you use a suitable HPF. Running full-range bass will still easily push them beyond Xmax with far less than 300W.

    I learned to play bass through a blackface Fender Twin. I eventually loaded it with JBL E120. I believe these were rated 150W RMS, so the pair had a 300W RMS power rating. As long as I kept the Bass control on the amp below about 4, I could use almost all of the amp's clean power. It's considered an 85W amp. So the drivers were hitting Xmax at about 28.3% of their RMS power rating.


    This should be inspirational/aspirational for you.

    [​IMG]
    Image from :Let's See Your Current Rigs!

    I believe he runs his DR201 through the 215 cab and the DR103 through the pair of 412s.

    I have a pair of Hi-Tone HT4121 which were modeled on vintage Hiwatt cabs. They are rated for 300W each. If I crank my DR103, I can push both beyond Xmax. Hiwatts do produce huge, extended lows.

    If you want to run guitar cabs I would suggest true biamping with an electronic crossover. Use whatever cab is necessary to safely produce the lows you need. Crossover the guitar cab over at 150hz or higher, and you should be relatively safe.

    I have experience with this. I used to run an Ampeg SVT and 810 crossed over at 200hz into the Fender Twin I mentioned earlier. It was a pretty phenomenal sounding rig, but it was totally impractical.
     
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  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    My earlier posts answerd your questions.
     
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  15. dabis

    dabis

    Mar 27, 2016
    Barcelona
    Hi @TTA! I've never tried it (at least conciously) but the experts do not support this:
     
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  16. paskisti

    paskisti

    Jan 20, 2005
    Notice that even you have such low F# tuning, you don't have too much fundamental in your signal. I would say nature of bass guitar is in upper harmonics more than the lowest fundamentals. I'm playing in Drop A tuning and indeed I'll cut the bass around 80hz with bass cab to make it clear and clean, without hum and mud. Probably you want punch and mids to make your bass sound good, and none of them live below 50hz IMO. If I'll play DI and IEM then I'll leave 80hz flat.
     
  17. J Wilson

    J Wilson

    Apr 22, 2022
    An Undisclosed Location
    none
    I'd also suggest that guys playing basses with the bottom string tuned to F# in national touring acts with vast FOH traveling systems and professionals to run them with huge power and subs big enough to park a minivan on . . . . are a world away from trying to build a bass rig to do this playing clubs. That F# is just about an octave below the open E string, and the difference in an amp stack carrying that open E vs. open F# is vast.

    In simple terms, it's 'do-able' if you spend a lot of money with Meyer Sound, not with MarkBass, Mesa, or anyone else in terms of contemporary bass guitar amps and speakers. There is a tremendous difference in performance between professional sound reinforcement gear and guitar and bass amps. In touring sound, this would be handled in a 3- or 4-way system with commercial crossovers and subwoofers. This sort of modularity does not exist, nor is there much of a market for it in bass amps and cabinets.

    Low F# is simply not designed into bass amps and cabs, for any number of reasons, and if needing to seriously and capably make F# and the rest of the notes down there, you have to go to the touring sound side of the house. Yep, that door, right there, C-Ya.
     
  18. TTA

    TTA

    Jun 10, 2021
    no one worries about making the fundamental though. It is about harmonics.
     
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  19. Ampslut

    Ampslut

    May 15, 2017
    Barrackville WV
    I don't think there are many bass amps that will reproduce the fundamental from a low B string let alone a low F#. Most bass cabinets don't go much lower than 40hz. One of the big calling cards of the Acme speakers was their ability to reproduce the 32hz of a low B string. (IMHO) those room shaking frequencies below 40hz are useful musically when used very sparingly.
     
    TTA likes this.
  20. CJC6

    CJC6 Supporting Member

    Jun 19, 2020
    I’ve been playing low F for a little while now. My Barefaced one10 is the best sounding cab I own for F# and below, it goes down to 30HZ.

    I can hear a usable difference. The Barefaced is being compared to a Subway 2x10, Aguilar SL112 and DB112.
     

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