Carvin FET 450 vs. Mosvalve vs. ISP Stealth

stm113

Power User
So I am trying hard to make a decision on a solid state power amp so I can stop using my 5150 head. There is a Carvin FET 450 on ebay for $275 & free shipping the auction ends in like 6 hours. I see Mosvalve often so there is no urgency and then there's the ISP Stealth, I had one before and it was great until I got to gig volume then it started to saturate a bit much (but in a musical way).

I own 3 4x12 cabs, all are 16 ohms which is one of my concerns since it seems most solid-state poweramp seem to like 8ohms and below. I could use 2 of the cabs together to drop the load to 8 but...no thanks, my back nor my equipment trailer would appreciate that. None of the cabs are stereo either. There's not much info out there about the Carvin FET 450 other than Queensryche used the FET 1000 on the Empire tour. I want to say also that I read somewhere that FET amps are the Next best thing to a tube power amp. The Mosvalves look to be under powered but I seem to remember hearing good things about them. Then there's the stealth, its so portable.

I just dont know what to do... any help is appreciated.
 
Carvin power amps (like pretty much all of their products) are high quality. I have some experience with FET amps, including the MosValve amps. My recommendation is to go with a Class D power amp. Carvin sells several options in their DCM series that are both lightweight and powerful. I use one of their DCM2000LX amps with my FRFR Fractal rig and it sound amazing. The amp is very neutral in tone, and just lets my programmed tones be heard without any coloration. My power amp weighs about 12 pounds and never runs hot, even after a four-hour show.

If you're looking for the power amp stage to have its own tube tone characteristic, in addition to FET options, you might look at the Quilter power amp blocks. I have a Quilter Aviator 2x10 as my "grab and go" small gig amp, and it sounds terrific. It has very tube-like tone, and is incredibly lightweight for a 2x10.

About the speaker / amp resistance mismatch, here's some thoughts to consider: it's generally safe to mismatch the amp into a higher resistance speaker load, so for instance, running a power amp output marked "8 ohms" into a 16 ohm speaker cabinet won't harm it, but it will obviously not be as loud due to the higher resistance of the drivers. But you don't want to mismatch it the other way by plugging a 4 ohm load into an output expecting to see 8 ohms or higher. The amp may overheat - or worse. The lower the resistance (in ohms), the closer you are to a short-circuit across the amp's positive / negative speaker outputs. The amp is expecting to see a minimum amount of resistance across the outputs, so let that be your guide for a minimum rating*. Also, if your 4x12 speaker cabs are currently rated at 16 ohms, you could rewire them to be 8 ohm stereo; I do this with my 4x12 cabs and it sounds great.

* Electrical engineers will point out that resistance is not just a fixed / round number for speakers. It varies across the sound spectrum for any given driver, and the cabinet has some influence on this as well. For the sake of simplicity, the resistance value of speakers is generally expressed as nice round numbers like 4 / 8 / 16 ohms. Some subwoofers are rated for 2 ohms (!). Also "ohms law" has some other interesting behaviors when speakers are wired in series or parallel. You can generally use the guideline that "two 8 ohm speakers in parallel = 4 ohms", and "two 8 ohm speakers in series = 16 ohms". There's a handy diagram on this web page, which would be useful if you were considering rewiring your 16 ohm cabs for 8 ohm stereo.
 
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