Indeed. Might be enough for the OP though. We don't know how big their room is or how loud they like to listen! At least it's a cheap and easy experiment to consider.
Can you wire the 2 subs in parallel ? At least then the amp has to work into 37.5 ohms.
Might be worth doing an impedance measurement sweep to see what they are actually doing between 20 - 100Hz as well.
Rob.
Might be worth doing an impedance measurement sweep to see what they are actually doing between 20 - 100Hz as well.
Rob.
There is virtually zero chance that the DC resistance of the subwoofer driver is 75ohms in this system. There are a number of reasons for that.
Start by putting a very large capacitor across the subwoofer terminals, then use a DVM to measure the DC resistance of the VC. The capacitor will help smooth out the measurement variations, because especially when the subwoofer is mounted in the enclosure, it will act like a mic at low frequencies.
Start by putting a very large capacitor across the subwoofer terminals, then use a DVM to measure the DC resistance of the VC. The capacitor will help smooth out the measurement variations, because especially when the subwoofer is mounted in the enclosure, it will act like a mic at low frequencies.
Be interesting to see photo of the 15" speaker driver.
Seen a few BP2000 15" speakers for sale on Ebay.
seem to be a 4 ohm eminence.
looks like typical stamp steel pro audio eminence speaker
with different cone.
I would say just keep the system original
find someone that can repair the plate amplifier.
Seen a few BP2000 15" speakers for sale on Ebay.
seem to be a 4 ohm eminence.
looks like typical stamp steel pro audio eminence speaker
with different cone.
I would say just keep the system original
find someone that can repair the plate amplifier.
Betcha it says "7.5 Ohms" (seven point five)
If conventional 4-8 Ohms, then DC resistance likely 5 Ohms or so. If 75 Ohms, then maybe 60 Ohms. Just guessing.
B.
If conventional 4-8 Ohms, then DC resistance likely 5 Ohms or so. If 75 Ohms, then maybe 60 Ohms. Just guessing.
B.
Ben,
Like the others in this thread that doubt the Turboegt's (the OP) measurement or make guesses about the impedance or DCR of the Definitive Technology 75Ω BP2000TL 15" woofer (P/N:1866A100-1, code #:4ABF), your "betcha guessing" is wrong.
Definitive Technology also uses drivers with DCR (DC resistance) of 4Ω, 24Ω, 30Ω, 32Ω, 60Ω, 64Ω, 100Ω, 108Ω, and 110Ω, (no 7.5Ω) as can be seen in this document from their website:
https://rn.dmglobal.com/usdefinitive/Subwoofer_grillsock_DCR_and_Raw_v1.1.pdf
Unusual, would be interesting to see what Definitive Technology's amp circuits are for the very high DCR drivers used.
Art
A few years back I repaired a DefTech amp for 75ohm woofer.(schematics attached)
Basically the power amp is a bridge arrangement powered directly from rectified mains, and is housed on a chassis separate from the backplate with preamp and controls. The only connection with the power amp is thru an optoisolator that carries PWM signal. Seems a lot of effort to avoid the cost of a beefy power transformer. Nowadays, a switch mode supply and class D amp are likely a better path.
I didn't take any pics at the time, but here are a few I found with a quick search that shows the 2 separate parts, and how the "Live" board was housed internal to the sub away from prying fingers.
I completely understand there are two boards. I actually sent both pair (amp and control board) them out to Beltronics in IL for repair but they couldn’t do anything with them. I ended up modifying the cabinets to house a Rockford Fosgate P2 15”. There is about 2.6ft of air space inside the DefTechs and the port is tuned to about 22hz so the Rockford sub should work perfectly. I debated modifying a plate amp to mount to the OEM black plate, but as I read reviews on different plate amps available all seems to have issues like turn on/off pop, too high of a turn on threshold, unreliable, ect. I ended up buying an AB International Precedent Series 600A which is rated at 450watts per channel at 4 ohms, perfect for the 400watts Rockfords. I’m currently waiting on new grills to be made before I reassemble everything and get them playing again. I will keep you posted on the results!
