And simply add a different Subwoofer (different in everything, from the size of the driver, the enclosure design, everything!) the manufacture said it will add a bottom end (again no low pass filter inside) and without worrying the group delay and phasing problem?

I got explaination from Mr. Wayne Parham, that there will be a problem, but in small room and with few driver I can't ignore that. But in the case of bass guitar cabinet, even for the stadium size concert?

Is that OK?

Regards,
Gabriel

I'd like to mention that there was a discussion on the HE forum a while back, mainly among bass guitar players, concerning how low they should go. Most agreed that the boxes didn't have to go very low, some even said that it actually tended to muddy the sound if they did, especially at gigs. It was also mentioned by a poster that the best sounding bass gear he ever heard from a stage had a roll-off already below 90Hz - more than one octave over the lowest fundamental...

Just my two cents, Gabriel :-) Good luck with your project!

Quote:"...didn't use a passive crossover, actually the have only hi-pass filter for the piezo?"

Well, one of the tricks that's in using a piezo is that it doesn't need a cross-over - it cuts off lower frequencies by itself, because of it's electrical/mechanical behaviour. How low the piezo goes depends on model - so you can simply choose one that only works over the area where the LF unit automatically rolls off. Then you have a cross-over less two way system.

Quote:"And simply add a different Subwoofer (different in everything, from the size of the driver, the enclosure design, everything!) the manufacture said it will add a bottom end (again no low pass filter inside) and without worrying the group delay and phasing problem?"

The only way to make shure the two systems won't interact in a negative way is to use an active (electronic) crossover & let them handle different frequencies. A socalled band-pass subwoofer will have a roll-off of ~12dB/oct over it's working area - but one still will have to make sure the other box don't interfere with it. No matter what the manufacturers say...

Having said that, I do recall having seen bass systems comprised of a box with four 10" units placed on top of another box with one 15" (or maybe 18"?) unit - but how they work, I don't know. If I know musicians, they may well ignore if there are problems of interferrence & such & simply run them in parallel, probably with two different amps. To musicians, it's more a matter of 'sound' - they usually don't care too much about all the tech problems the hifi/audiophile/whatever crowd finds important. The solution with two boxes makes ot possible for the musician to only take one box (prolly the 4X10) to smaller venues, & then supplying it with the 15-18 box a bigger ones.

Quote:"But in the case of bass guitar cabinet, even for the stadium size concert?"

Huh? At such large venues there's usually a big PA system solely devoted to directing sound to the audience. The people on stage then have various monitor speakers to be able to hear themselves & the rest of the band proberly. Without being an expert, it's my impression that the bass players at such venues simply use their own equipment (including speaker!) as their 'monitor' - if they (the bass players I mean) play such large gigs they usually have systems of their own large & loud enough to be able to 'compete'. So if that's the direction you're goin', be ready to build something big! Or do as described above, build two smaller ones - I'd still go for making two that are alike, though.

And I still don't see why you wanna complicate things overly with a 'sub'...

Thank's again

Well, the typical 'hifi' speaker & the typical instrument amp speaker are different for various reasons. An instrument speaker have to be durable & able to withstand hard use & at the same time be able to play loud enough, at least to compete with acoustical instruments (Which in themselves can be surprisingly loud!). So usually, instument speakers are pretty large & efficient, with the drivers having proberties to meet the demands - furthermore instrument speakers (& amps) often have a certain 'sound' that acts as a prolonging of the sound of the instrument itself. The typical 'hifi' speakers are much smaller & at least try to be neutral in their sound, + be able to deliver bass from small boxes. And so, they are also much less efficient than most instrument speakers. There's a lot more to it than this, but this is the short version. :-)

A typical driver (speaker unit) for instrument use will be quite large & have a light diaphragm & a stiff suspension.

A typical driver (for bass/midrange) for hifi is smaller & have a heavy diaphragm & a soft suspension.

I should add that the people you meet in this forum & the High efficiency forum to a certain extend contradicts the above! They often use professional drivers & correspondingly large boxes in order to achieve a more dynamic sound, &/or be able to reach reasonable loudness levels with small tube amps. They still try to achieve a neutral sound, though I do think it's fair to say that they probably emphasize other aspects of the sound than your average audiophile...

Quote:"...lately I know that it because of the delay."

Quote:"....and also eliminate all the problem in the gig."

Uhhh - as far as I can see the problem simply is that the sound from your rig mixes with the sound from the PA when you crank it up - but because of the distances in question, the sound from yours arrives a bit later & screws up the sound heard by the soundman (& audience!). It's a bit hard to see how that problem can be solved - I mean, regardless of the type of rig you use the problem will occur as soon as you turn the volume up loud, right? & that's the same also if we only talk bottom end.

It's true that the idea of a stacked set comprising one 4X10 on top of a 1X15, covering by & large the same frequencies looks terrible from a hifi point of view. But it might well work fine as an instrument speaker! You cannot compare the two uses totally, you know.

I really think you should go into the High Efficiency Forum & post a message called "Bass guitar speakers - help" or something. As I mentioned, several of the posters there are bass guitarists AND very knowing about the technical aspects of speakers, too. Be sure to make it as clear as possible what your problems are, also mention what gear you like/dislike & what you want a solution to do - they are a helpfull bunch, & the more specific you are, the better help they can give!

The High Efficiency Forum is a part of this site & can be accessed from the main page - there's also a link to it here:

• HE-forum