HELP!!!! :Bass Guitar Cabs

[moose54]

Just to let u know the 15" will be a Kappa Pro 15 mounted in a 120L vented and tuned to 50Hz... Seems to be consistent with other bass cab designs.

hmm yeah the tweeter might not be necessary. The band I’m with is a punkier rock type style so I don’t know if the horn would be necessary. That's y I wanted peoples opinions. But if mounting a horn in series with a cap is all I'd need to do then that would be simple enough. The horn is just for simple attack and plucking noises... sometimes upping the high end on the amp can give enough with out a horn... hmmm I guess the horn was more of a challenge so I'd still like to know how to do it... I guess I could build it with out the horn and if I decide later I want one then I could add it...

y the 600 and not the 300 model??? Well the local music guy usually does me a good deal and it’s either $1200 for the 300W or $1550 for the 600W so y not have the head room????

To follow that sangram (I could chase up the calcs) but what frequency would the -3db point of the horn be?? How would that affect the impedance of the box?? The woofers are in a nominal 8ohm alignment. Let me know if I am correct here, but as the frequency increases the resistance of the woofers increases. By the time the high frequency driver (if 8ohm nom) kicks in, the resistance of the woofers would be high enough that the nominal resistance of the box would stay at 8 ohm.

Thanks for the ideas... keep them rolling

[moose54]

opps for got again.... I had a go at soem configuratrions with the Kappa Pro 10 and i can't get a nice response in my calcs.... the gamma 10 has a much nice response.... hmmm i know what you are saying about cast framse but it just doesn't look too pretty...

[Le Basseur]

About the horn decision:you look rather undecided about this....As long as you play the music you said you do,honestly I don't see any reason for having a tweeter....unless you want a Victor Wooten-like tone in your band
The 1st order filter recomended by sangram has the only advantage (beside of being a 6 dB/oct,not 3 dB/oct,as you wrote) of having the best behaviour regarding the phase and transient response.The BIG problem with these filters is that the cutoff freq must be calculated far away,maybe at an ensuring 4,5~5 KHz.Remember,there is a special category of horns for PA,able to withstand big power (the so-called "ring").The construction (and the price) of these horns are a totally different story.
As you said,it looks fair enough to build the cabinet without horn,wich can be added later (and tested outside the box,for that matter).
About the amp,OK,go for the bigger one,if the price argument prevails.As you said,you'll have some more headroom,not to speak that your guitarisd wouldn't dare to compete with a 600 W bass amp...
Don't worry too much for the specs of the Kappa Pro 10's...what's on paper can oftenly be non-realistic in real life.If I were you,I'd pay more attention on sound,not on specs.After all this isn't a very picky issue,it's a bass cab,not a high-end box!

Please do some reading on how a crossover network works,what are the implications regarding the impedance,etc,etc.In short,the points you mentioned aren't of concern,everything is OK:
1.the overall impedance doesn't suffer at all because the existence of a passive crossover.
2.The rising impedance of a woofer can be liniarised by using a so-called "zobel filter",but in your case,it's more like a suplimentary pain in the a...Once more,the drivers have a specific construction,different of the hifi woofers.

[Le Basseur]

Originally posted by sangram
A 2.2 uF film cap rated at 1000 volts will be a nice 6 dB/octave XO for the horn, even at many hundred watts. If you're only playing bass on the rig, not much chance of blowing up the horns because HF content will be very low - just finger noise if at all - unless the amp is oscillating.

Inductors in a Passive XO for bass rated at 1000+ watts is ridiculous. Bass boxes don't need that - actually a terrible idea since bass runs closer to rated RMS ratings than a full music spectrum - a 600 watt RMS amp is some sort of a minimum for gigging, specially with a lot of drums and distorted guitars around... Enough to melt a coil or a dozen of them.

Maybe a steeper slope for the tweeter can be used 12 dB/ 18 dB, but the natural rollof of the driver at the top end should be used if pairing with a tweeter - no series inductor is necessary. If you're really worried about frying a tweeter you can add a fusible R in series, rated to blow at tweeter overload...

Right,folks,WITHOUT the inductance in a hi-cut network running at high power.Unless you want a free smoke machine..
The cutout response should be solved by a special design of the cab itself.

[usekgb]

I would recomend goind without the horn. The frequency of the bass guitar only goes so high anyway. Also, are you building a full range PA cab, or a bass cab? A lot of the sound of the instrument comes from the cab. If you add the horn, you will hear a lot of string noise, hiss, and electronic garbage. There's a good reason that most bass amplifiers don't have horns. They just sound better without them. BTW, the last time I saw the Flectones, Victor Wooten didn't have a horn in his bass rig.

As for as the Kappa Pro's go, try tuning the enclosure higher. You've already got that big 15" doing the low end. Let the 10's handle the mids and highs. I haven't run the numbers on them yet, but it should work pretty well. In my eminence book, I have a volue recommendation between 5.6 and 8.5 liters. For 4 speakers, that would be between 22.4 and 34 liters. Give it a try with these volumes, and don't worry about making the cab go down to 20 Hz. You should be pretty happy with the results.

Cheers,
Zach

[Le Basseur]

Originally posted by usekgb
I would recomend goind without the horn. The frequency of the bass guitar only goes so high anyway. Also, are you building a full range PA cab, or a bass cab? A lot of the sound of the instrument comes from the cab. If you add the horn, you will hear a lot of string noise, hiss, and electronic garbage. There's a good reason that most bass amplifiers don't have horns. They just sound better without them. BTW, the last time I saw the Flectones, Victor Wooten didn't have a horn in his bass rig.


Cheers,
Zach

Having or not a horn mounted in a bass cab remains an open question.I'd not say that the bass guitar freq response stops where you think they do...it depends enormously on the bass itself,strings,pick-ups,effects and so on.Also,deciding wether to use or not a horn is,as I already said,a matter of taste and,before all,of the style of playing.Just think about Anthony Jackson,Lincoln Goines,Mathew Garrisom and others who use the tandem Fodera-Epifani.It's something wrong with their sound?I don't think so...
As for the Victor Wooten's tone,I never saw him "live",so I cannot have any comment on what he uses.When I referred to him,I actually meant on his "slap" sound and way of playing.If you're a slapper,a tweeter mounted in your cab definitively brings in another "flavour".

[moose54]

34L???? that’s tiny.... its actually inconveniently small. 138L is around the minimum volume I’ll be looking at. That’s a standard 615x615x450mm guitar cab. I want the two to able to fit together nicely... hmmm the tuning frequency...

Some one answer me this and this may sound like a stupid question. OVER EXCURSION... this is what kills drivers yes??? other then clearly over powering them which will in turn have the same effect... now... when producing frequencies below the tuning point there is less resistance on the drivers cone movement yes??? thus reducing its power handling capabilities and i could destroy the driver.... tell me if i am correct here... that may be wrong but i'd like to know. (I lent my speaker design book to someone so i can't look it up)....

If this is the case, what is the max freq I should be looking to tune the box to?? As this is one of my first vented enclosure I’m a little timid about blowing the drivers.... and i really don’t want to have to pay for some new ones.... i know i need to expect some errors in learning this stuff but I’ll try to avoid any problems i can...

Thanks again

[sangram]

To be honest the only reason I suggested that particular value was that that was exactly what I used for building a little home practice rig for my Bassist. I haven't the calc here, but I guess the XO point would be somewhere near 5 or 6 KHZ, which gives the horn some relief from handling very low freqs. I also added a 10 ohm resistor in series to tone down the high end - this is to taste, YMMV.

I find the bass sound to be much better with the horn. There is definitely an added flavour by bringing in some some string noise. The overall impedance of the box does go a little haywire but the Zobel is pretty heavy duty (It's an amp based on TDA 7294 non-inverting config of course) so the dips and nulls in the impedance at higher frequencies are well taken care of - also because it's PA the Zobel (1 R/ 100 nF) can be a little 'stronger' to cure instabilities of long leads, etc.

This also takes care of the rising impedance of the woofer. The advantage we guitarists and bassists have is we can concentrate on 'tone' rather than 'hi-fi' so some speaker non-linearity may not really matter too much - I have unfortunately no way of telling you about the impedance curve - the entire setup was made with parts I had left over except for a transformer - and I have no measurement gear at all.

I know the horn will never get damaged because of the huge attentuation - it barely gets any energy anyway - except when my stupid little pianist plugged his yamaha into the amp one day. The tweeter wasn't damaged, but it was about 110 dB sensitive. The pianist suffered quite a bit of damage.

Again, I think the most sensible suggestion is to build without the horn - save the money, then add it and see if you need it at all, especially for the tone you want. That's more important than theory and guessing. Tone is everything when you're making music, and only you know what tone you want...

[Le Basseur]

Originally posted by sangram




- except when my stupid little pianist plugged his yamaha into the amp one day. The tweeter wasn't damaged, but it was about 110 dB sensitive. The pianist suffered quite a bit of damage.

This is a good one,I like it!
YES!!!YES!!!!
But..don't pretend too much....remember the old saying:"..Please don't shoot the pianist! It's the only one left!"
Cheers,

[moose54]

hmmm sounds decent sangram.... might have a look into it. As for padding the high end?? I think i'm going to have to if i go for the horn, or it will be too sensitive.. I'm tipping you need a fairly high wattage resistor too yes???

Some cabs have a variable pad on the horns. I guess they simple use a pot, but once again wouldn't the power handeling have to be fairly high?? that is something that would be nice to incorporate as well...... so many ideas

hmm looks like you guys didn't see my last post either... I'm still on "probation" mode... if you have a chance and could look back (when it gets past security) and reply that would be awesome..

out

mark