Bass Amp Idea

[Ripcord]

Ok, I've had an Altec 515B woofer and a Morel MDM55 dome midrange laying around for a couple of years and started wondering if the combination of the two would make a cool bass amp. Something in the practice/ studio/small gig size. Would like to make it a tube amp but not locked in to that. Some nice wood, combo amp, small. What do you think?

 

[Chris Daly]

Hi
Looks like a nice project, you could look up history info about Marshall or Fender
for what goes into designing a bass amp.. that works

The Altec 515B is a 16 ohm speaker
http://www.lansingheritage.org/images/altec/specs/components/414a-515b-803b/page2.jpg

it would best suit a valve amp for reasons explained here:
Valve Amps: Valve verses Solid-state amps

As for a crossover for the midrange, design appropriately for that driver,
Some ideas for crossover here based on the excellent midrange of the Gale
GS401a GS401 Speaker | galeaudio.com

Cheers / Chris

 

[sreten]

Hi,

The 90dB dome is going to struggle used with any 15" good for bass.

In theory you could make a great small combo with a 15" (or 12")
suited to the Morel (i.e. more a hifi driver), for the more laid back
styles of bass. But neither driver has the presence peak of rock bass.

Or the mind numbing +110dB sensitivity of this around 5KHz :
http://www.eminence.com/pdf/BGH25_8.pdf
Now that is the sort of thing you want connected to a valve amplifier.
Too much that you can cut is always better than not enough.

rgds, sreten.

 

[Loudthud]

The 515B might not do well in a small enclosure. Some of these old speaker designs want a 10 cubic foot box for a maximally flat alignment. Try to find the Thiele-Small parameters or measure them, then do a simulation. You want to find an alignment with a controlled mid-bass peak (1 or 2dB) and gentle roll off to perhaps -10dB at 40Hz. Resist the temptation to tune the box higher than 40Hz to keep the cone from farting out.

 

[Ripcord]

Thanks Guys. Loudthud, I did find the thiele-small parameters for the Altec 515B. Attached is the suggestion of the online bass box software that I used. I'm not locked in to the 515B, I just have one. I also have two of the Morel MDM55's. I'm not a bassist but have always wanted to build a bass guitar amp. Sreten, thanks for the ideas. I love that bass horn. I was trying to use up stuff that I have but it is pretty cool.

 

[Loudthud]

The low Qts of the 515B makes it suitable for a small box. I would build the 3.27 cu ft box and tune it to 40Hz. Power capability is limited. Something like the old Ampeg B15N would be cool.