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Speaker gurus, I need your help (re-speaking some cabs)!

Discussion in 'Amps and Cabs [BG]' started by andruca, Oct 28, 2005.


  1. andruca

    andruca

    Mar 31, 2004
    Madrid (Spain)
    Hi everybody!

    Ok, so after almost 10 years of playing thru Hartke gear i've grown a little tired of alluminium. The thing is I'm saving to get me a Schroeder 310212 cab (now, fortunately available in Europe thru an Italian distributor). But I also need to have two rigs so I'll keep my current Hartke (215XL + 4.5XL) setup. The thing about the Hartkes is that they go for very low prices used here. So maybe, it's no worth it to sell them if, with no more than 500€ I can replace the drivers with paper coned ones. I can get the complete line of Eminence drivers for (relatively) cheap, thru a german online store. I've been doing some playing around with some of these drivers and came to a final choice. First of all, my cabs' internal volumes are as follows:

    4.5XL -> 180liters / 6.36 cu.ft. (currently 8ohms)
    215XL -> 230liters / 8.41 cu.ft. (currently 4ohms)

    I power these cabs with one channel each of a stereo power amp (280W@8ohms/450W@4ohms / 700W@2ohms).

    So, first of all, and according to volume I could use Kappa Pros or Gammas for the tens (Legend BP102 speakers, could give me a much more "low" cabinet, i guess, but I'd need a couple more cu.ft. -am I right on this one?-) and Magnum HO or LF, Kilomax, Omega Pro, Kappa, Lappa LF, Kappa Pro, Kapa Pro LF, Delta LF, Delta, Gamma or Beta for the fifteens. Unfortunately Legend CB15 is one of the few I haven't available there.

    According to Eminence's speaker selection guide, and given that I always hi-pass my 4x10" (at around 100Hz), I could use Gamma 10s (read EBS uses speakers with identical specs for their 4x10). For the 2x15" it's a little tough, but according to said guide, Kappa 15LFs would be fine (Kappa 15s are claimed to be more specifical for bass, according to Eminence -may be less "sub-oriented"- but have too short Xmax -1.5mm?- and also need a smaller enclosure -once again, according to Eminence's site-). I definitely can't afford Kappa Pros, and they're a little poorer in terms of sensitivity.

    I've been playing around these in WinISD and it's doable with some minor re-tuning of my cabs. Now I can easily (relatively) match technical data and find drivers that "numerically fit" in my cabs, but I absolutely lack the experience and associated intuition as to not miss my goal completely, nor even dream about predicting how a cab could sound with a particular driver (although I understand pretty well how to analize group delay and such "sound predicting" data). So this is where I need your experience and advice. I'm particularly concerned in my 2x15 being reasonably low but tight at the same time (despite Hartkes' "signature" tone, they're not boomy at all now, I can't particularly complain about that, I'm ok with their "tightness").

    As an additional comment I normally run Stingray 5 -> SansAmp RBI -> Power Amp, with EQ almost flat (just taking off some hi mids to tame the Hartke speakers natural increase in that range -moreso with the Stingray, not so much with my Fernandes Gravity, which I seldom user thru this rig-) and definitely don't boost low frequencies (I have enough with the 15s' natural thickness). Generally I need to cut thru a ska-punk band (just one guitar, but three brasses) and a (2 loud guitars) rock&roll band. Don't have problems up to now, but I definitely don't need to get lost in sub-frequencies (and sometimes I boost around 125-150Hz -with a 1.5 octave Q- some 3dB to be present).

    Please, I just need to know if this is a reasonable alternative, and if not, what would you put in my cabs. But not missing my somewhat limited my budget (I cannot go throwing Kappa Pros everywhere nor can afford more power to feed them but maybe can climb up to 600€ maximum budget limit if something more adequate is worth the extra cash).

    Thanks so much for your help! I appreciate your valuable knowledge and learn from it every day!

    ANDRUCA
     
  2. andruca

    andruca

    Mar 31, 2004
    Madrid (Spain)
    Bump! Anybody? Thanks!

    ANDRUCA
     
  3. Download my spread sheet. Sort the sheet by the Vb (box volume) and Diameter columns.

    Divide the cabinet net volume by the number of drivers. For example, your 215XL is 8.4 cubic feet, so volume is 4.2 cubic feet per driver.

    Find close matches in my spread sheet and see if they meet your needs.

    Note there are Vb columns for (3) vented alignments and (2) sealed alignments. The QB3 vented alignment is most popular, then the Optimal Flat alignment used by WinISD. The SBB4 gives a large box and lower tuning, with a corresponding higher F3, but better transients.
     
  4. andruca

    andruca

    Mar 31, 2004
    Madrid (Spain)
    Hi bgavin!

    Thank God you're there, man! I guess I'm ok then with the kapa 15LF for the 2x15" cab (4.15 cu.ft. each driver vs. my available 4.2 cu.ft.) for a QB3 alignment. I'm tuning this one a little lower than Fs (39Hz), at 34Hz, 'cause I play 5 string (sometimes even dropped to low A). I should change the ports for longer ones (easy). It works ok in WinISD, with a group delay of 17ms@27.5Hz, the lowest note I play (tight enough, AFAIK).

    Regarding tens, I think Gammas are not that ideal (although they are almost ideal in volume terms for a SBB4 alignment -1.56 cu.ft. vs. my available 1.59 per driver-) because they have this very short Xmax (1.6mm) which is exceeded (even doubled according to WinISD) at the around 90Hz excursion peak (takes only 100W to hit Xmax). I'd have to hi-pass the cab at around 150Hz to avoid it from hitting Xmax at very low power. This would leave my cab very inefficient in the midbass range, just where I need it most. So I tried the Legend BP102s and they work ok when I put tem in my 4x10" and tune to Fs (it's 40Hz, but it'd be tuned to 41.5Hz without even touching the box -better in this case as altering this cab's tuning would be a rather intrussive job-). Peak group delay is 14ms@27.5Hz (again, my lowest note). The best part of this is that this cab can go lower with BP102 drivers (I can even use it as a stand alone for small gigs!).

    What do you think? Am I in the right path or missing it completely? Are the described group delays "around standard"/"reasonably tight" or are they on the muddy side?

    Thanks so much!

    ANDRUCA
     
  5. Don't get too mired in group delay mud. Studies show humans can hear 25msec or more delay, but humans can tolerate more delay as the frequency goes even lower.

    In the audiophile arena, a sealed cab delivers the tightest bass, by far. It is also reproducing recorded music, and not producing live music in a band mix. Big difference.

    Depending on your bass, you may or may not have much fundamental. The best one can hope for is a fundamental of the same amplitude as the 2nd harmonic. I've seen much discussion and analysis of basses that are much stronger in the 2nd harmonic, meaning less or little fundamental. This is a prime factor in choosing your live music cabinet.

    If your bass fundamental is significantly weaker than the 2nd harmonic, your cab needs are easier. Look for a cab with rock solid performance to 62 Hz (B-string 2nd harmonic). I put my JBL E155 18" into a new cab that does this. It is tuned at 65 Hz for flat bass to 82 Hz, but it is WAY down -16dB at 41 Hz. This is the natural rolloff for this driver anyway, so I did a cab that fits it.

    You can test this with a 31-band EQ: drop all the sliders from 50 Hz and lower to full cut. If your sound doesn't change much, or at all, your bass is mostly 2nd harmonic and higher. If the bottom falls out, then you need something that will go lower.

    This is best done playing through a good HiFi stereo system which is designed to produce full range bass. I use the stereo to hear what my bass "really" sounds like... very much different than played through bass cab speakers.

    The Gamma is a driver for PA, not electric bass. The BP102 look good, but requires sufficient cabinet volume to reach full potential. If you stuff them into a smaller cabinet, you will get a mid bass hump in the 80 ~ 120 Hz range. You may, or may not, care for this. Eden XLT have this hump, and are very popular. It gives the (false) impression of strong bass.

    You can fuss over tuning +/- 0.001% and it will still change as the driver gets up to operating temperature, or the weather changes. Nit picking. Eminence drivers exceed Xmax before they exceed their input power rating. The Xmech (damage) spec is FAR higher, which is why they don't self destruct, but wind up melting the coils instead.
     
  6. andruca

    andruca

    Mar 31, 2004
    Madrid (Spain)
    I've already noticed this. My main bass is a Stingray 5 and it has way stronger fundamental than my second basses (2 of them) which are Fernandes Gravity Deluxe fivers. I have this cheap Behringer parametric EQ (PEQ2200) that has built-in 4th. order hi-pass and lo-pass filters. I did the 50Hz test last week and noticed no change with the Fernandes but it DID in fact sound different with the MusicMan. So I guess I'll get as much fundamental as I can.

    I'd already discarded Gammas because they're not "Xmax-safe" for my needs. I need clean strong bass. I also need to cut thru, so maybe the mid-bass hump ends up being a good thing for me (I use to reinforce a little around the 100-150Hz area).

    Yes I see that. That's bassically why my speakers will be WAY underpowered to obtain clean bass. The RMS handling of my boxes will end up being 800W (for the 4x10) and 1200W (for the 2x15) and I will power them with 450W each (don't even need half that power). The thing is I need them to be fresh where the current Hartke drivers give up (400W RMS each box is just the thermal limit, they fart WAY before that -although I seldom need to go that far-).

    Thanks so much again for your help! God bless you!

    ANDRUCA
     
  7. If your intent is producing clean bass at high loudness levels, buy or build Bill Fitzmaurice's Tuba and DR2xx bass horns.

    To make a lot of clean noise, you have to haul a substantial amount of gear. That can be a lot of direct radiator cabinets, or a few bass horns. The cubic volume will probably be about the same, either way. My two 1x15 subwoofers measure 7.5 cubic feet each. This is the same cubic volume as a single Tuba 30, which blows the doors off my two subs, and does it with MUCH less input power.

    One of the builders over on Bill's forum has a pair of Tuba30 for sale right now. I don't know the particulars, other than they are finished in truck bedliner, and have the recommended Magnum 12HO driver installed.

    Bass horns aren't for everybody, because they have a (lack of) coloration all their own. The sound is decidedly different than direct radiators, especially the absence of doppler distortion. The clean sound may, or may not, please you.
     
  8. mikemulcahy

    mikemulcahy

    Jun 13, 2000
    The Abyss
    I am gonna grow up and be as smart as Bruce someday.


    Mike
     
  9. Hey Mike, did I make you angry?

    If so, not intended.

    :confused:
     
  10. mikemulcahy

    mikemulcahy

    Jun 13, 2000
    The Abyss
    Absolutely not, was a sincere compliment, I am envious of you brilliance in speaker-ology. The best I can do is plug the damn thing in. Sorry for any confusion.

    Mike
     
  11. andruca

    andruca

    Mar 31, 2004
    Madrid (Spain)
    I've considered this for a future project. I'm developing a taste (reading and learning a lot) for speaker design (and DIY in general). Just trying not to literally have to give my Hartke cabs away for a few pennies here. Being in Europe I'll buy Bill's cab plans and, as I'm not woodskilled at all, I'll "subcontract" the woodworking to a carpenter I know. Thanks so much!

    ANDRUCA

    EDIT: Excuse my ignorance, but, isn't group delay (or muddyness in general) an issue on horns? Are Tubas articulate enough? Thanks!
     
  12. Dont worry about muddyness or group delay: horns have far less issues with this then bassreflex cabs. The only problem with horns tend to be some comb filtering issues, but i think Billfitzmaurice took care of that in his designs. Also remember that the carpenters costs could mount quickly: these horns take a lot of working hours to make. Some other horn plans can be found at: www.speakerplans.com .