Any advice on building an ev Georgian Ii?
- Thread starter Bicyclist
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grindstone
Well-Known Member
Bicyclist
Super Member
Yes I am. On further investigation I see the top driver is a 12" and not a ten. Not sure a ten wouldn't be better though. The horn is generally crossed at 2k or so, so a fairly small midbass might be in order.
elitopus
Addicted Member
If you just want to build Georgian inspired speakers, the drivers don’t have to be exactly what they used. A 10” woofer should be able to go low enough to meet the 18” woofer, and high enough to meet the horn. I think it would work just fine.
What are you using for crossovers?
What are you using for crossovers?
Bicyclist
Super Member
Just spit balling right now but I would probably build crossovers to start with. I'd need to do some research on crossover points and what the slopes might be. The real issue will be where to put them when they are finished. I can build them in my garage but the house already has a lot of hifi in it.
grindstone
Well-Known Member
FWIW. Not much is known. From private conversations years ago, the EVSA engineer was named David Norman.
Bicyclist
Super Member
That helps, apparently they were crossing that horn at 1500.
Bicyclist
Super Member
That would be ideal, I don't really have the gear to do that. End game id like it to be driveable by 15 or so tube watts. I was thinking 200hz crossed to the 10 then 2k to the horn but that would mean the ten had better sound really great.
Bicyclist
Super Member
Salient questions! I have evm-18bs the 10inch drivers are actually from some old p.a. cabinets loaded with a 15" ev force, a stamped basket 10 with a really heavy magnet and the ht94s. I need to dig both of those out to get the particulars on them. Also I have a pair of sp12bs I could use instead of the 10s.
Post a picture of the 10". Can't place which cabinet that was (that they came from)...
If there's a label on the side of the magnet, be sure to post a picture of that. Especially if it has a number like 10xxxx or "67", followed by four more digits, on it.
Regards,
Gordon.
If there's a label on the side of the magnet, be sure to post a picture of that. Especially if it has a number like 10xxxx or "67", followed by four more digits, on it.
Regards,
Gordon.
Bicyclist
Super Member
I'll go out to the garage in a day or so. I really appreciate your sharing your knowledge!
That's definitely either a DH3 or a DH2010 (effectively the same thing, the so-called "witch hat" driver).
There's no reason you couldn't make an outstanding speaker with an EVM18B, a SP12B and a HT9040/DH3.
I'd probably use the 18B at about 125Hz and down, and the SP12B from about 125Hz to 1500Hz or so.
You could probably actually start with an E-Wave crossover (the greater-than-95dB version), for the mid-high crossover, and just add a crossover on the low out of the E-wave crossover to separate the 12" from the 18". A 20mH choke and 80uf cap, in both the lowpass and highpass parts, could work fine. I'd suspect that the sensitivity of the 18" and 12" would be pretty close- you might have to put a slight L-pad on the 12", if there's too much midrange compared to bass- then just adjust the L-pad on the E-wave crossover to blend in the horn...
Put the SP12B in about 2 cubic feet sealed, with the enclosure completely filled with fiberglass insulation.
The 18B needs a big box- optimally 12 cubic feet. Incorporating the 2 cubic feet for the midrange, into the enclosure volume, and building it out of commonly available 3/4" thick plywood- that would wind up being about a 2 foot by 2 foot by 4 foot enclosure, outside dimensions. You could reshape that, but the total internal volume would need to be between 13 and 14 cubic feet, all combined...
That speaker could easily be driven by 15 watts per channel. Easily a 98dB/1w sensitivity, or close.
Regards,
Gordon.
There's no reason you couldn't make an outstanding speaker with an EVM18B, a SP12B and a HT9040/DH3.
I'd probably use the 18B at about 125Hz and down, and the SP12B from about 125Hz to 1500Hz or so.
You could probably actually start with an E-Wave crossover (the greater-than-95dB version), for the mid-high crossover, and just add a crossover on the low out of the E-wave crossover to separate the 12" from the 18". A 20mH choke and 80uf cap, in both the lowpass and highpass parts, could work fine. I'd suspect that the sensitivity of the 18" and 12" would be pretty close- you might have to put a slight L-pad on the 12", if there's too much midrange compared to bass- then just adjust the L-pad on the E-wave crossover to blend in the horn...
Put the SP12B in about 2 cubic feet sealed, with the enclosure completely filled with fiberglass insulation.
The 18B needs a big box- optimally 12 cubic feet. Incorporating the 2 cubic feet for the midrange, into the enclosure volume, and building it out of commonly available 3/4" thick plywood- that would wind up being about a 2 foot by 2 foot by 4 foot enclosure, outside dimensions. You could reshape that, but the total internal volume would need to be between 13 and 14 cubic feet, all combined...
That speaker could easily be driven by 15 watts per channel. Easily a 98dB/1w sensitivity, or close.
Regards,
Gordon.
Correct. In 12 cubic feet, they go down to a rolloff frequency of about 38Hz.
If you shrink that to 8 cubic feet, they roll off at about 50Hz.
You can EQ that to go lower than 50Hz- but that would require more than 15 watts.
Regards,
Gordon.