Picked up a Carver MXR-150 "The Receiver" last month from the same guy I got my SX-1980 from. I've been distracted with the Pioneer but finally got around to attending to the Carver.
I've always been a bit suspicious of the Carver gear - maybe it's just that he was so ingenious sometimes that it's hard to believe the hype - but I've never been one to shy away from the Kool Aid so lets give this one a chance.
The Carver utilizes an unusual "Magnetic Field Power Amplifier" which I think is Bob Carver talk for a switching power supply akin to your computer's power supply.
The most noticeable aspect of this is that it doesn't have a large (heavy & expensive) power transformer like other amps.
I'm curious to hear how this compares at 150 watts x 2 with my other receivers in that category - I don't imagine it could have the dynamic headroom and 'punch' of conventional amps but then Caver has been known to be a magician so I'll keep that mind open.
Big problems with these are the output / speaker relays.
They're not up to the task apparently and commonly need to be replaced. Typical symptoms are that you get no audio output or some audio output at high volume levels. The contacts get toasted & pitted. I believe that the relays are configured such that when you select 2 pair of speakers the load is in series versus in parallel which is more typical. Presumably this is to avoid a low impedance load across the outputs. As a result of this I think the load is alway across both relays with either 1 or 2 pair of speakers.
The original relay is part number 621D024 - a 24 volt low current coil and DPDT (2-form "C").
There is a gentleman on ebay selling a pair of these for $20 + shipping but I sourced these from www.mouser.com. The Mouser part number is 677-OMI-SH-224D and the manufacturer's part number is OMI-SH-224D,594. Oh, they're a bit cheaper at $2.46 each - not that cost is an issue with any of us !
Replacing the relays is only a bit tricky as you have to unsolder the 8 legs holding the speaker binding posts to the assembly and then replace the relays. At least there is plenty of room to work in.
Next project will be to replace and slightly relocate some 2-watt resistors with 5-watt versions. These tend to burn the PCB so I'll be getting them up and away a bit more than stock.
For now, some sexy (nude) family pictures.
The pretty face...
The clear one is the original relay and it's $2.46 replacement...
Mounted on the PCB...
Reassembled and back into the chassis...
I've always been a bit suspicious of the Carver gear - maybe it's just that he was so ingenious sometimes that it's hard to believe the hype - but I've never been one to shy away from the Kool Aid so lets give this one a chance.
The Carver utilizes an unusual "Magnetic Field Power Amplifier" which I think is Bob Carver talk for a switching power supply akin to your computer's power supply.
The most noticeable aspect of this is that it doesn't have a large (heavy & expensive) power transformer like other amps.
I'm curious to hear how this compares at 150 watts x 2 with my other receivers in that category - I don't imagine it could have the dynamic headroom and 'punch' of conventional amps but then Caver has been known to be a magician so I'll keep that mind open.
Big problems with these are the output / speaker relays.
They're not up to the task apparently and commonly need to be replaced. Typical symptoms are that you get no audio output or some audio output at high volume levels. The contacts get toasted & pitted. I believe that the relays are configured such that when you select 2 pair of speakers the load is in series versus in parallel which is more typical. Presumably this is to avoid a low impedance load across the outputs. As a result of this I think the load is alway across both relays with either 1 or 2 pair of speakers.
The original relay is part number 621D024 - a 24 volt low current coil and DPDT (2-form "C").
There is a gentleman on ebay selling a pair of these for $20 + shipping but I sourced these from www.mouser.com. The Mouser part number is 677-OMI-SH-224D and the manufacturer's part number is OMI-SH-224D,594. Oh, they're a bit cheaper at $2.46 each - not that cost is an issue with any of us !
Replacing the relays is only a bit tricky as you have to unsolder the 8 legs holding the speaker binding posts to the assembly and then replace the relays. At least there is plenty of room to work in.
Next project will be to replace and slightly relocate some 2-watt resistors with 5-watt versions. These tend to burn the PCB so I'll be getting them up and away a bit more than stock.
For now, some sexy (nude) family pictures.
The pretty face...
The clear one is the original relay and it's $2.46 replacement...
Mounted on the PCB...
Reassembled and back into the chassis...
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