Looking to build an OB based on Altec components that I have. So far I have a set of 511b horns with 908 compression drivers and a set of 921 speakers. Has anyone ever used those speakers in a OB build before? I'm going to use a miniDSP for a cross over. GPA said that the 921 speakers can be reconed as 416 speakers. One speaker needs reconing so I may go that way.
Any suggestions?
Thanks
BillWojo
Any suggestions?
Thanks
BillWojo
silverprout, when I look at the Altec spec sheet of the 921 it list the "maximum cone excursion" as 1/2" or about 12.5mm, am I missing something? I know little about speaker design but am trying to learn. This is a 16" LF driver with a power rating of 200W continuous of pink noise.
Thank you
BillWojo
Thank you
BillWojo
Oups, sorry you are right.
What a nice driver, you have a QTS of 0.25, a Fs of 34Hz and a light cone of 80Gr.
It is a great candidate but it depends a lot of your room size and your expectations, my 18" don't go deeper than 40 Hz and i don't expect any chest compressions.
Well I'd love to have VOTT speakers in my living room but that's not going to happen. So lets stay on the OB plan. Besides, I hear people raving about there OB builds so I figure there must be something to them. I have several pair of subs if I feel that they don't go low enough.
I have been offered a set of clean Altec 421 speakers with Alnico magnets for not much more than getting my 921's reconed. Any thought on the 421's?
Thanks
BillWojo
I have been offered a set of clean Altec 421 speakers with Alnico magnets for not much more than getting my 921's reconed. Any thought on the 421's?
Thanks
BillWojo
My 18" baffle is 0.5 x 0.5 x 0.01 meters (1ft 8in x 1ft 8in x 0.4in)
The volume occupied in my room is 25L= 0.88in
It look like a small electrostatic panel with its 0.4in thickness.
It's only my opinion (not really but...) but equalize an overdamped loudspeakers sound better in OB.
High Qts drivers lacks of cone control and seems a lot less detailed to my ears.
Altec Thiele-Small Parameters
Your 921 have officially 1.27mm of excursion.
This design is totally devoted to a horn application... i suspect yout to are already aware of that
silverprout your making me painfully aware of that. Speaker design is not near as easy as I thought. What's going to complicate this is that I was hoping to run the woofers off my 40W MC40 tube amps.
Today I ordered new aluminum diaphragms for my 908 drivers, basically turning them into 902 drivers. With the new diaphragms I'll be crossing at 800Hz.
Have any ideas for 15" high efficiency woofers that are good to over 800Hz? I'm just starting to look at whats out there.
Thanks
BillWojo
Today I ordered new aluminum diaphragms for my 908 drivers, basically turning them into 902 drivers. With the new diaphragms I'll be crossing at 800Hz.
Have any ideas for 15" high efficiency woofers that are good to over 800Hz? I'm just starting to look at whats out there.
Thanks
BillWojo
A thought just came to me. Sitting in a pile of boxes here is 8 original Carver 12" woofers from my Amazing Platinum ribbon speakers. They will need refoaming to use them. 4 ohm, maybe I could use 2 per side wired in series.
Direct replacements are the Dynavox WP-1220 drivers. They are not very efficient at 88db/w/m though. Might need to drive the low end with SS.
Any thoughts on this?
BillWojo
Direct replacements are the Dynavox WP-1220 drivers. They are not very efficient at 88db/w/m though. Might need to drive the low end with SS.
Any thoughts on this?
BillWojo
Properly implemented they can work well, if that's what you are looking for.
You will need them but you have now lost the advantage you are trying to gain from going boxless.
Same thing. You are ignoring that you need high Q drivers to make this work easily. A high Q driver has a hard time coming to a halt after the signal ends and a lot of people like the warmth that adds to the sound. Personally I prefer the opposite but let's move on. Low Q drivers are well damped and not at all suited for OB without oodles of power and heavy EQ. If possible, consider drivers with a Qts of 0.7 or higher. The one advantage you have is a tube amp. These have a low damping factor and are well suited to OB use.
Hi Cal, I'm looking at some woofers that I already have that need to be refoamed. I have a question up on THECARVERSITE to try and figure out the Qts of them. I know a replacement for a similar speaker that Bob used on another style of ribbon amazings has a Qts of over 3 so I suspect mine will be very close to that.
I'm not ignoring you guys, just trying to learn as I go. Thanks for pointing me in the right direction.
BillWojo
I'm not ignoring you guys, just trying to learn as I go. Thanks for pointing me in the right direction.
BillWojo
I'm sorry, these loudpeakers shoud be fantastic in a horn loaded baffle, but bass horns are very big.
A light cone of 15" should be ok for 800Hz and you should have no regrets for OB because you can add a large woofer to your configuration.
And keep your 15 in relatively small closed or BR enclosure... (IMHO there is no better sounding drivers avaliable in the 70-100Hz range)
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