Star Gazing

Hi all, real newbee here.

Quickly. I have some drivers that came out of old (70's I guess, plastic multiconnectors) Magnavox and Penncrest consoles. Most of them have the small bent magnet that I associate with alnico speakers. While trying to look up part numbers, alnico speaker info and stuff about how to make/buy a crossover for them, I came upon the Linkwitz Orion page. I like it!!

So, for my first DIY speaker I starting construction on a simplified Orion style speaker with the 10" drivers mounted on one sheet of 3/4 birch plywood, not semi-boxed like the original. After I registered I searched 'alnico' and 'open baffle' and came across a picture similar to what I was mocking up in the garage. I don't have the post but the picture was titled orionsservosub011. Thank you.

I'm using old alnico speakers because I have them already, but I'm hot on alnicos anyway because I believe (remember,limited experience here) they have some points I like;
-I like the old tube radio sound and, in testing these drivers unmounted with my 15wpc Pioneer 4050 garage tuner, I still get that sound.
-I think they're louder than a lot of other speaker for a given watt of power (although after looking on Partsexpress I'm seeing there a quite a bit of mid-90db speakers available at friendly prices).

So I guess my first question is:

-What kind of sound should I expect from these old alnicos in an open baffle design?
My first thought is that they won't be able to go very low, maybe 100Hz and that they'll absolutely need a crossover to sound anywhere near 'good'.

All these drivers (4/10", 2/8", 4/4", 2/2.5" and 2 1"(?) horns) cost me less than $40 and so are perfect for the learning phase of this DIY speaker. I can experiment between the 4"/2.5" combo for the tweeter vs the horns, etc. I know a crossover will be the key here and it will tax my brain to the limit if I have to build one.

Next question would be:

-What would be a good, simple, relatively inexpensive crossover for these speakers?
I can solder well. I just don't have a good grasp on the electronics part of it all.

Finally, thoughts for the FUTURE:

I currently use a pair of Boston CR8's and a 65wpc Carver HR-742 reciever. IIRC the CR8s only go down to 48Hz and I'd like to get down closer to 40Hz.
-In order to do this should I consider going to 12" drivers for this instead of staying with 10"?

For instance- The Jensen P10R 10" has an Fs of 97 (Jensenvintage.com) and the Eminence Legend 1028k 10" (Partsexpress.com) has an Fs of 95. Where as the Jensen P12R 12" has an Fs of 75 and the Eminence Legend 1228k has an Fs 67.

-Could any of these speakers even get down to my current 48Hz in open baffle?

Or I guess what I'm asking is; Should I consider going to ceramic drivers or maybe a mix of ceramics and alnicos to get down to 40Hz and still have a vintage tone?

FWIW- I listen to all most anything except rap/hip hop and opera. I only use stereo, no DSP or home theater. My room(s) are...... smallish. I have a 1931 home with wood floors.

Boy that's a lot of info / questions? Any responses would be of help. Thank you.

R/

Jim
 
2litre said:
Hi all, real newbee here.

Quickly. I have some drivers that came out of old (70's I guess, plastic multiconnectors) Magnavox and Penncrest consoles. Most of them have the small bent magnet that I associate with alnico speakers. While trying to look up part numbers, alnico speaker info and stuff about how to make/buy a crossover for them, I came upon the Linkwitz Orion page. I like it!!

So, for my first DIY speaker I starting construction on a simplified Orion style speaker with the 10" drivers mounted on one sheet of 3/4 birch plywood, not semi-boxed like the original. After I registered I searched 'alnico' and 'open baffle' and came across a picture similar to what I was mocking up in the garage. I don't have the post but the picture was titled orionsservosub011. Thank you.

I'm using old alnico speakers because I have them already, but I'm hot on alnicos anyway because I believe (remember,limited experience here) they have some points I like;
-I like the old tube radio sound and, in testing these drivers unmounted with my 15wpc Pioneer 4050 garage tuner, I still get that sound.
-I think they're louder than a lot of other speaker for a given watt of power (although after looking on Partsexpress I'm seeing there a quite a bit of mid-90db speakers available at friendly prices).

So I guess my first question is:

-What kind of sound should I expect from these old alnicos in an open baffle design?
My first thought is that they won't be able to go very low, maybe 100Hz and that they'll absolutely need a crossover to sound anywhere near 'good'.

All these drivers (4/10", 2/8", 4/4", 2/2.5" and 2 1"(?) horns) cost me less than $40 and so are perfect for the learning phase of this DIY speaker. I can experiment between the 4"/2.5" combo for the tweeter vs the horns, etc. I know a crossover will be the key here and it will tax my brain to the limit if I have to build one.

Next question would be:

-What would be a good, simple, relatively inexpensive crossover for these speakers?
I can solder well. I just don't have a good grasp on the electronics part of it all.

Finally, thoughts for the FUTURE:

I currently use a pair of Boston CR8's and a 65wpc Carver HR-742 reciever. IIRC the CR8s only go down to 48Hz and I'd like to get down closer to 40Hz.
-In order to do this should I consider going to 12" drivers for this instead of staying with 10"?

For instance- The Jensen P10R 10" has an Fs of 97 (Jensenvintage.com) and the Eminence Legend 1028k 10" (Partsexpress.com) has an Fs of 95. Where as the Jensen P12R 12" has an Fs of 75 and the Eminence Legend 1228k has an Fs 67.

-Could any of these speakers even get down to my current 48Hz in open baffle?

Or I guess what I'm asking is; Should I consider going to ceramic drivers or maybe a mix of ceramics and alnicos to get down to 40Hz and still have a vintage tone?

FWIW- I listen to all most anything except rap/hip hop and opera. I only use stereo, no DSP or home theater. My room(s) are...... smallish. I have a 1931 home with wood floors.

Boy that's a lot of info / questions? Any responses would be of help. Thank you.

R/

Jim


low bass is completely dependent on baffle size (wider the better for bass)

read up on mocking up xovers... also you need to do some testing to see how far those speakers can play accurately (this will help you choose xover points)

www.partsexpress.com for the inductors and capacitors for the xvoer... resistors too (if you research enough to make a good decision)