This has bad idea written all over it, but here goes... I have a dual 1 ohm voice coil speaker that my friend sold me for next to nothing (RE Audio 18") that can handle 5000 watts RMS. I've been contemplating building a box for it and wiring it up to my home system. I have an extra output I'm not using on my crossover. The problem I'm having (aside from how much overkill this is) is that I can't figure out how to properly power it: if the voice coils are in series, I get a reading of 1.7 ohms. I'm looking at feeding it 2000 watts ideally and I can't find the right power amp. Nothing seems to be stable below 4 ohms in bridged mono. Does anybody have any creative ideas?
Take out all fuses and any circuit-protection, then increase rail voltage to desired level and enjoy the show! Have fun!
ReAudio says 1500watt thermal powerhandling
Your best chance is to NOT bridge your amps
Besides, they promise 87db, so I dont think you need that much power
Crown XTi promise 700watt in 2ohm
Your best chance is to NOT bridge your amps
Besides, they promise 87db, so I dont think you need that much power
Crown XTi promise 700watt in 2ohm
Use a transformer? A 240VAC to 120VAC isolation or autotransformer could convert 1 ohm impedance to 4 ohms. That's how I run my Contrabass which has a 1 ohm voice coil.
Or, there's the brute force chip amp approach: use enough LM3886es in parallel or bridged to handle the load. They're almost as cheap as power transistors. This'll need a substantial power supply; maybe a rewound microwave oven transformer, or one from a car battery charger or arc welder.
And, something I've speculated about: take a stereo amp, disable one channel's driver section and add its output devices to the remaining channel. This may be least problematic with a MOSFET amp, since presumably at low frequencies the added capacitive load on the drivers won't be a factor. People who know something may shoot this idea down in flames.
Or trade the speaker for something that's easier to use.
Or, yeah, settle for much less power. Due to issues with the NAD2200, I'm currently running one Contrabass and a 1259 from a little 40 watt/channel DIY amp (Reg Williamson's 40/40). I haven't noticed any shortage of bass, but then I have been exercising some self-control with the volume knob ever since a neighbour informed me her house was shaking.
Or, there's the brute force chip amp approach: use enough LM3886es in parallel or bridged to handle the load. They're almost as cheap as power transistors. This'll need a substantial power supply; maybe a rewound microwave oven transformer, or one from a car battery charger or arc welder.
And, something I've speculated about: take a stereo amp, disable one channel's driver section and add its output devices to the remaining channel. This may be least problematic with a MOSFET amp, since presumably at low frequencies the added capacitive load on the drivers won't be a factor. People who know something may shoot this idea down in flames.
Or trade the speaker for something that's easier to use.
Or, yeah, settle for much less power. Due to issues with the NAD2200, I'm currently running one Contrabass and a 1259 from a little 40 watt/channel DIY amp (Reg Williamson's 40/40). I haven't noticed any shortage of bass, but then I have been exercising some self-control with the volume knob ever since a neighbour informed me her house was shaking.
For a low cost option, I suppose I could run a Behringer EP4000 on one channel at 2000 watts to 2 ohms (but it seems like a waste to leave that other channel just sitting there).
Where do I find more information about using transformers? I'm interested to see if I could make that work.
Where do I find more information about using transformers? I'm interested to see if I could make that work.
"Behringer EP4000 on one channel at 2000 watts to 2 ohms"
The EP4000 is only rated at 1250W/2R RMS, the 2KW rating is 'peak'.
It won't run very long at 2R before overheating.
The EP4000 is only rated at 1250W/2R RMS, the 2KW rating is 'peak'.
It won't run very long at 2R before overheating.
I wouldn't use the Behringer, but there's a lot of pro amps that fit your needs.
Look into QSC & Crown, you can mod the amps' fans with quieter ones if need be.
Or you could always get it re-coned with new soft parts and higher impedance VCs. If it's an older RE driver, Scott @ Fi can still work on them 🙂 Dual 1 ohm with 5kW power handling sounds like you have an MT 18", meant for SPL competition.
Look into QSC & Crown, you can mod the amps' fans with quieter ones if need be.
Or you could always get it re-coned with new soft parts and higher impedance VCs. If it's an older RE driver, Scott @ Fi can still work on them 🙂 Dual 1 ohm with 5kW power handling sounds like you have an MT 18", meant for SPL competition.
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What model 18" is the RE Audio driver? They do make more than one 😉 The driver with the highest power rating i know of is the "XXX" & there are two flavours of these. The earlier model had an xmax of about 35mm & had a glued on dustcap, the later model had a one piece cone & a 54mm xmax & higher power handling 🙂 I believe the later model would handle 2000W RMS, not quite sure about the earlier one but it'll be less.
The voice coil resistance doesn't sound right either as they are 2 ohm per coil, so again, what model is it?
If it's one of the custom jobs that they can supply like the MT series it might explain things.
The voice coil resistance doesn't sound right either as they are 2 ohm per coil, so again, what model is it?
If it's one of the custom jobs that they can supply like the MT series it might explain things.
Actually, now that I think about it...some of the MTs came with much tighter gap tolerances in the motor, so they weren't able to be reconed with different coils...for the purpose of maximizing performance for SPL "burps".
A good friend of mine in college (who works at Fi now, incidentally) ran a 15" BTL - basically an updated MT - as his home theater sub with a QSC RMX series amp. Thing had some attitude when playing Xbox, that's for sure 😉
A good friend of mine in college (who works at Fi now, incidentally) ran a 15" BTL - basically an updated MT - as his home theater sub with a QSC RMX series amp. Thing had some attitude when playing Xbox, that's for sure 😉
I believe it's an older MT with the glued on dust cap. I got it off of my friend 4 years ago and he had it for a while so it's got to be around ten years old. Supposedly it was a preproduction test speaker before he got his hands on it. It's a dual 1 ohm coil setup. The magnet is about 3" deep and 9 inches in diameter. He was powering it in his car with a 2400w RMS amp into it at 2 ohms. He was actually using 8 gauge as speaker wire. It's absolutely massive. Aside from that, I don't have that much info on it.
I'm not looking at breaking the bank to power it, because it will see pretty limited use (I have a feeling the neighbors may complain).
I'm not looking at breaking the bank to power it, because it will see pretty limited use (I have a feeling the neighbors may complain).
Those specs don't add up 😉 Just for starters i have never heard of any amp that'll more than double the output power into precisely half the load impedance (look at 8 ohm & 4 ohm per channel).
The current draw is wrong to unless my maths is seriously amiss, 2000W per channel & a max of 84% efficiency looks like 20A+ to me, yet they are claiming 15A with a 4 ohm load per channel which would be 4000W+ per channel RMS & at least 40A+ @ 230V....
Yeah right, pmsl 😀
In my workshop at the moment I have an early example of a Rauch DVT 250 M (Mono) Internally this is a Stereo Lateral Mosfet PA Amplifier. It has 2 x 1KVA transformers and 16 Hitachi lateral fets. The 2 Output boards are linked with stout wires. There is only one driver board that runs all 8 pairs of output fets.
The Rauch DVT 250S is rated at 550W per channel into 4 Ohms Stereo
The Rauch DVT 250M is rated at 1100W into 2 Ohms Mono.
It would seem perfectly practical to take a good quality stereo mosfet amp that was rated for 4 ohm per channel and mono it for a 2 ohm load.
Indeed some crown amps can be configured as linked mono, to drive 2 ohm speakers.🙂
Frankly I have got no idea how they do it but given that it is an extremely highly regarded pro amp (and not cheap at £3.5k) it would be all over the respective fora (forums?) like a wildfire if it would not deliver what MC2 promises. If anything MC2 is usually rather conservative with their specs given that the vast majority of their customers run their amps flat out for years and insist on total reliability. For touring amps MC2 and LabGruppen is as good as it gets but unlike LabGruppen MC2 are also used in studios. I got one of my own MC2s from Abbey Road mastering when Abbey Road started to get sponsored to use other amps.
Now i know LabGruppen are serious bits of kit 😀
I had a thought & wondered what class of amp this MC2 is, the 4.5KW might have been a misprint which would even things up a tad. If the amp was a 3 or 4 stage class H or class D it might be able to do those power specs & if so i suspect that when the say "nominal" they mean playing music & not pure sign waves.
£3500 you say 😱 It wants to be on spec at that price..
It's MC2s first ever class D amp, designed by Duncan Hamilton (design engineer of MC2 and XTA). All of their other amps were designed by Terry Clarke (who founded Klark Teknik) and Ian McCarthy and are regular class AB jobs. E90s seem to be quite popular as they are frequently sold out and MC2 has the capacity to produce something like 10 000 amps per annum. Then again may be not that surprising as the equivalent LabGruppen amp is listed at £6.6k!
I use three MC2 amps in my little home stereo: a T500, an MC750 and an MC450.
The 450 is black and badged Tannoy (Tannoy used them until they got bought by TC Group who also own LabGruppen), the 750 is badged as Quested Audio (that's the one from Abbey Road). DynaudioAcoustics also used MC2 until they too were bought by TC Group, doubled the prices for spare parts and stopped supplying the diy speaker market. MC2, Quested Audio and XTA merged a few years ago and manufacture all their gear in Honiton, Devon AFAIK.
I use three MC2 amps in my little home stereo: a T500, an MC750 and an MC450.
The 450 is black and badged Tannoy (Tannoy used them until they got bought by TC Group who also own LabGruppen), the 750 is badged as Quested Audio (that's the one from Abbey Road). DynaudioAcoustics also used MC2 until they too were bought by TC Group, doubled the prices for spare parts and stopped supplying the diy speaker market. MC2, Quested Audio and XTA merged a few years ago and manufacture all their gear in Honiton, Devon AFAIK.
Ah, that changes things just a tad 😉 In that case it's quite possible that 4.5KW into 4 ohm wasn't a misprint. With the output filter being required to work between 8 & 2 ohm it's possible it's most efficient at a 4 ohm loading.
Cheers for the heads up 🙂
So it seems this could get pretty expensive pretty quick... I'm still interested in the transformer idea though. Where would I find a resource for information on that?
My other thought is to take my old JBL 4646As on my current amp, run them parallel at 4 ohms on one channel at 750 watts and run the single channel to the RE Audio sub at 2 ohms to get 1250 watts. That approach happens to be free...
My other thought is to take my old JBL 4646As on my current amp, run them parallel at 4 ohms on one channel at 750 watts and run the single channel to the RE Audio sub at 2 ohms to get 1250 watts. That approach happens to be free...
2000W?....Thats a lot.
As it s about 90V peak, you ll need +-100V rails.
Best is to use two amps bridged, cuting in two the
supply voltage requirements, but then, each amp will
have to stand 1000W on a 1 ohm load, that is 45A peak.
This require each amp to have at least 12 ouput power
devices pairs to be reliable..
Quite an ambitious project.
As it s about 90V peak, you ll need +-100V rails.
Best is to use two amps bridged, cuting in two the
supply voltage requirements, but then, each amp will
have to stand 1000W on a 1 ohm load, that is 45A peak.
This require each amp to have at least 12 ouput power
devices pairs to be reliable..
Quite an ambitious project.
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