Hey all, I recently picked up an ultimax 18, and I need roughly 550 watts into 3.2 ohms to drive it. Ive got a gfa 555 ii I thought would be plenty ran in mono, but boy does it protest when running the sub. Distortion lights stay lit, and eventually I blew the dc rail fuses in one channel. My nad 2200 wouldnt even go out of protection with the sub connected in bridged mono. Either amp does OK running on one channel, but I didnt buy an 18" to have "OK" Performance, and I dont love the idea of pushing one channel right up to the brink constantly.
I have restored/fixed/built every amp ive owned, so im not afraid of getting my hands dirty, but im not exactly sure what direction to go. I want something monoblock that will honestly run a 2 ohm load, and make at least 400w into 4 ohm, preferably even more for some headroom. Quite the task as Im now realizing. I looked at inukes and crowns, and im just not willing to put something so crass into my system after meticulously choosing and building my main amps for low distortion. Buying and fixing and adcom gfa 565 (roughly $900) or a hypex 1200 module (slightly more expensive) are my first 2 ideas. But I cant help but feel like im missing something. If you have a suggestion for another amp, vintage or diy prefered that I can get into for under a grand please let me know.
I have restored/fixed/built every amp ive owned, so im not afraid of getting my hands dirty, but im not exactly sure what direction to go. I want something monoblock that will honestly run a 2 ohm load, and make at least 400w into 4 ohm, preferably even more for some headroom. Quite the task as Im now realizing. I looked at inukes and crowns, and im just not willing to put something so crass into my system after meticulously choosing and building my main amps for low distortion. Buying and fixing and adcom gfa 565 (roughly $900) or a hypex 1200 module (slightly more expensive) are my first 2 ideas. But I cant help but feel like im missing something. If you have a suggestion for another amp, vintage or diy prefered that I can get into for under a grand please let me know.
That power is achievable. I worked for a company (Jands Electronics) that made 2 x 2kW amplifiers for PA applications, rock concerts and similar. They also made a MOSFET amplifier 2 X 800W that measured & sounded very nice. The local (Australian) production stopped after I left the company... some 25 years ago. They now have a 2 x 1.8kW amplifier that may be of interest to you... NOT made by Jands.... I do not have any info or experience on this model:
https://www.jands.com.au/dynacord-power-amplifier-2-x-1800w-at-4-ohms-intergal-dsp-dyn-l3600fd.html
... it seems it will drive 2 ohms at 3kW.
https://www.jands.com.au/dynacord-power-amplifier-2-x-1800w-at-4-ohms-intergal-dsp-dyn-l3600fd.html
... it seems it will drive 2 ohms at 3kW.
I have a Peavey PV-1.3K that is rated at 1000 w/ch into 2 ohms. Bridged rated 2000 w into 4 ohm. Designed about 1994.
10 output transistors per channel. MJ15024/25 . 8" diameter fan. Transformer is about 30 lb. Rails are +-85 v.
Protection mode is the downfall, no relay. Protection is a crowbar triac that detects DC and shorts the output to blow all the already hot output transistors. Crowbar will not blow the mains breaker. Just melts the lands to the triac off the board instead.
I was trying to stuff a NFET rail cutoff in the chassis ahead of the output transistors, but when my home was burglarized work stopped. My audiences aren't that big. A CS800s driving SP2(2004) is entirely too loud for my audiences. They are happy at 50 watts on a bogen speaker and the elder complains if the bass can be heard. His wife will not touch the pedals on the organ.
10 output transistors per channel. MJ15024/25 . 8" diameter fan. Transformer is about 30 lb. Rails are +-85 v.
Protection mode is the downfall, no relay. Protection is a crowbar triac that detects DC and shorts the output to blow all the already hot output transistors. Crowbar will not blow the mains breaker. Just melts the lands to the triac off the board instead.
I was trying to stuff a NFET rail cutoff in the chassis ahead of the output transistors, but when my home was burglarized work stopped. My audiences aren't that big. A CS800s driving SP2(2004) is entirely too loud for my audiences. They are happy at 50 watts on a bogen speaker and the elder complains if the bass can be heard. His wife will not touch the pedals on the organ.
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Most things rated for 4 ohms are right at the limit - 3.2 ohms load suggests finding an amp that's happy to drive 2 ohms, as the driver's impedance curve will drop well below the DC value at resonance. Class D might be wise at those power levels and impedances.
I have a NAD 2200 and if your's is not going out of protection I think their might be a problem with it. I don't believe the NAD is a good amp for subwoofer use. There are many better amps to choose from. The NAD is only a 100 watt @8ohms amp with great headroom but the power supply and outputs are only designed for 20 milliseconds so trying to use it a a subwoofer amp is really leaning on its design.