Bass player wants to design a cabinet for a 350W head

[Juan Vallejo]

Good day!

I'm a bass player and I recently bought an Ampeg PF350 class D amp head and I want to build a cabinet with Eminence equipment. I'm able to make a baltic birch plywood cabinet in my work (we got a CNC and we use these kind of plywood in daily basis) so that would be the easy part for me, however I'm not familiar with driver units, crossovers and the whole nine yards (although I know what are they for).

Since my amp head delivers 350W @4 ohms and 250W @ 8 ohms, the first thing that comes to my mind is to get a 4 ohms 12 or 15" driver so I can put all the power in just one driver (would be great to squeeze all the power through just one driver so my gear won't be unnecessary heavy and roomy. I'm also thinking on getting a 450 - 600W rms driver thinking ahead on getting a more powerful amp without having to get a new cabinet.

One thing that I know is that the sound that I'm looking for needs also a supertweeter (like many brand bass cabinets) so I can get a nice low end response while keeping brightness, but while surfing the Eminence webpage I only can get 8 ohms supertweeters, so at this point I don't know if I'm looking for a nonsense, so here come the questions:

1. It would be possible to get a nice combination of crossover and supertweeter able to work in a cabinet with a single 4 ohms driver?

2. If no, that means that I have to go for a cabinet with a couple of 8 ohm drivers so I can get a supertweeter unit?

3. If anyone os familiar with this, could you suggest a crossover for this usage?

BTW, I was looking for this Eminence driver models:
KAPPALITE 3012LF-4
DELTA -12LF
DELTA PRO 12-450-4
DELTA -15LF-4
KAPPALITE 3015LF-4

This is the rear panel from the amp head that I got.

Thanks for your support!

 

[markw]

If you run two eight ohm supertweeters in parallel, it will be seen as a four ohm speaker.

 

[Swerd]

Welcome to Audioholics. There are several regular posters here who know a thing or two about designing and building audio speakers, but I know nothing about building speakers for guitar amps.

Knowing a little about the frequency range of bass guitars, I wonder how a 'super tweeter' could be of any use, but as I said, I know nothing…

One the internet sellers of Eminence drivers is Parts Express. They are known for giving good advice to audio speaker builders, and they might be able to help you with your questions too. Call them and ask for Tech Support.

 

[Swerd]

Since you did ask specific questions, I'll take a stab at answers.

Yes, a crossover can be made with a 4 ohm woofer and an 8 ohm tweeter. But before you pursue that, think about some different options.

Instead of one large 12" or 15" woofer, consider using two smaller 8" or 10" woofers. If you get two 8 ohm woofers, they can be wired in parallel making it a 4 ohm load for the amplifier. Two smaller woofers offer several advantages:

1. They can put out as much volume as one larger woofer, with less distortion.
   
   
2. Smaller woofers are capable of higher frequency sound than larger ones. With that you might not need a tweeter.

Obviously, smaller woofers may not go as deep as a larger one, but frequencies below roughly 40 Hz may not be the major concern for bass guitar.

 

[TLS Guy]

Good day!

I'm a bass player and I recently bought an Ampeg PF350 class D amp head and I want to build a cabinet with Eminence equipment. I'm able to make a baltic birch plywood cabinet in my work (we got a CNC and we use these kind of plywood in daily basis) so that would be the easy part for me, however I'm not familiar with driver units, crossovers and the whole nine yards (although I know what are they for).

Since my amp head delivers 350W @4 ohms and 250W @ 8 ohms, the first thing that comes to my mind is to get a 4 ohms 12 or 15" driver so I can put all the power in just one driver (would be great to squeeze all the power through just one driver so my gear won't be unnecessary heavy and roomy. I'm also thinking on getting a 450 - 600W rms driver thinking ahead on getting a more powerful amp without having to get a new cabinet.

One thing that I know is that the sound that I'm looking for needs also a supertweeter (like many brand bass cabinets) so I can get a nice low end response while keeping brightness, but while surfing the Eminence webpage I only can get 8 ohms supertweeters, so at this point I don't know if I'm looking for a nonsense, so here come the questions:

1. It would be possible to get a nice combination of crossover and supertweeter able to work in a cabinet with a single 4 ohms driver?

2. If no, that means that I have to go for a cabinet with a couple of 8 ohm drivers so I can get a supertweeter unit?

3. If anyone os familiar with this, could you suggest a crossover for this usage?

BTW, I was looking for this Eminence driver models:
KAPPALITE 3012LF-4
DELTA -12LF
DELTA PRO 12-450-4
DELTA -15LF-4
KAPPALITE 3015LF-4

This is the rear panel from the amp head that I got.

View attachment 18484

Thanks for your support!

Is this for a four or five string bass? It makes a difference as a five string needs a frequency response of 30Hz to 5 KHz. A four string 40 Hz to 5 KHz. Those extra 10 Hz complicate matters immensely.

You don't need the smoothest speaker for guitars. A 15" woofer and piezo horn mid and tweeter make a good cheap and cheerful set up.

I have designed instrument speakers before. I'm busy at the moment, but I can design this for you if you can be a little patient.

This is very different from audio speaker design. We have never got into instrument speaker design on this forum before I do not believe.

 

[highfigh]

Since you did ask specific questions, I'll take a stab at answers.

Yes, a crossover can be made with a 4 ohm woofer and an 8 ohm tweeter. But before you pursue that, think about some different options.

Instead of one large 12" or 15" woofer, consider using two smaller 8" or 10" woofers. If you get two 8 ohm woofers, they can be wired in parallel making it a 4 ohm load for the amplifier. Two smaller woofers offer several advantages:

1. They can put out as much volume as one larger woofer, with less distortion.
   
   
2. Smaller woofers are capable of higher frequency sound than larger ones. With that you might not need a tweeter.

Obviously, smaller woofers may not go as deep as a larger one, but frequencies below roughly 40 Hz may not be the major concern for bass guitar.

Never heard a bass player try to get a decent sound on the low string of a 5 or 6 string bass, eh? The E string fundamental is 41.2Hz and the B is around 31Hz. With PA system support, it's not a problem because the amp is DI'd, but the player still needs to hear something from the low strings on stage. Then, there's the that the bass guitar, drums and possibly, keyboards can all occupy some of the same low frequency range and if all three are producing sub-50Hz notes, it gets ugly in a hurry. This is part of the reason most PA systems don't do much below 50Hz, unless it's for a specific reason. Almost all of what a bass player hears from their rig is mid-bass because they may be too close. Some like to feel the rumble, some don't need it and some like to hear their sound at higher SPL, some don't.

Granted, the sound we perceive as "deep bass" is the first harmonic but as in a music reproduction system, if the driver can't produce enough energy at the lower frequencies, it's useless. Also, the excursion for a 31Hz note is more than most 8" drivers want to experience.

 

[highfigh]

Good day!

I'm a bass player and I recently bought an Ampeg PF350 class D amp head and I want to build a cabinet with Eminence equipment. I'm able to make a baltic birch plywood cabinet in my work (we got a CNC and we use these kind of plywood in daily basis) so that would be the easy part for me, however I'm not familiar with driver units, crossovers and the whole nine yards (although I know what are they for).

Since my amp head delivers 350W @4 ohms and 250W @ 8 ohms, the first thing that comes to my mind is to get a 4 ohms 12 or 15" driver so I can put all the power in just one driver (would be great to squeeze all the power through just one driver so my gear won't be unnecessary heavy and roomy. I'm also thinking on getting a 450 - 600W rms driver thinking ahead on getting a more powerful amp without having to get a new cabinet.

One thing that I know is that the sound that I'm looking for needs also a supertweeter (like many brand bass cabinets) so I can get a nice low end response while keeping brightness, but while surfing the Eminence webpage I only can get 8 ohms supertweeters, so at this point I don't know if I'm looking for a nonsense, so here come the questions:

1. It would be possible to get a nice combination of crossover and supertweeter able to work in a cabinet with a single 4 ohms driver?

2. If no, that means that I have to go for a cabinet with a couple of 8 ohm drivers so I can get a supertweeter unit?

3. If anyone os familiar with this, could you suggest a crossover for this usage?

BTW, I was looking for this Eminence driver models:
KAPPALITE 3012LF-4
DELTA -12LF
DELTA PRO 12-450-4
DELTA -15LF-4
KAPPALITE 3015LF-4

This is the rear panel from the amp head that I got.

View attachment 18484

Thanks for your support!

Are you trying to limit the cabinet size, too? The Delta-12LF (is it the LF-A?) doesn't work with a tiny cabinet if you really want it to rumble. It can be pretty punchy, though.

Have you looked on the TalkBass forum? Two of the members are pretty well-known for their cabinet designs and one (Bill Fitzmaurice) designs cabinets that are lightweight and easier to move. Greenboy (who designs 'Fearful' cabinets) has some excellent designs, too. Both have very happy users.

Greenboy-
http://greenboy.us/fEARful/

Bill Fitzmaurice-
http://www.billfitzmaurice.com/