I have an opportunity to purchase a pair of Amber Series 70 amplifiers. They work well, no hum, or other audible issues in stereo mode. I plan on using them in a shop/outdoor area as mono blocks, they have a switch stereo/mono. One amp has instructions to run in mono, mainly using left input and using the 2 red (positive) outputs. this does not work, no output. If speakers are hooked up to the left outputs, positive and negative, I get output. The amps run barely lukewarm at moderate sound levels, but need to know if this method of speaker connections for mono use is okay. Hate to blow them up, decent sounding amplifiers I'm sure they will need recapping, due to age.
Any help would certainly be appreciated, the manuals on HiFiEngine do not have any recommendations for mono use speaker hookup that I could find.
Thomas
Any help would certainly be appreciated, the manuals on HiFiEngine do not have any recommendations for mono use speaker hookup that I could find.
Thomas
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They both have the stereo/mono switch. as 4A line fuse amps, they must not be particular powerful in stereo. 60 W/ch maybe? 1/2 1A*120 VAC? 120 W in, 60 W out per channel.
One way to double power in mono, is for the mono switch to invert the left input and present it to the the right input. Then left amplifies straight through, right inverts with an op amp, the speaker between hots of both channels sees double the voltage.
Do both amps work at full power in stereo mode on both channels? That has to work for mono to work this way.
If both work that way, then mono not working must mean the switch is dirty (likely after 30 years) or the signal is not making it through the connectors to the inverting op amp. Tin or brass oxide can be cleaned off connectors by removing & replacing, but dirty switches have to be sprayed out with contact cleaner or replaced. I like CRC cleaner myself. Warning, contact cleaner is flammible, no smoking, open flame, electricity turned on or off within 30 feet. Set up a fan beforehand to dissipate the fumes.
Or the inverting op amp has shorted input causing both channels to go dead when mono switch turned on. Not very likely.
Never heard of Amber, but respect the Made in Charlottsville, VA label. I tried to get a job in Staunton 38 years ago, ended up here instead.
One way to double power in mono, is for the mono switch to invert the left input and present it to the the right input. Then left amplifies straight through, right inverts with an op amp, the speaker between hots of both channels sees double the voltage.
Do both amps work at full power in stereo mode on both channels? That has to work for mono to work this way.
If both work that way, then mono not working must mean the switch is dirty (likely after 30 years) or the signal is not making it through the connectors to the inverting op amp. Tin or brass oxide can be cleaned off connectors by removing & replacing, but dirty switches have to be sprayed out with contact cleaner or replaced. I like CRC cleaner myself. Warning, contact cleaner is flammible, no smoking, open flame, electricity turned on or off within 30 feet. Set up a fan beforehand to dissipate the fumes.
Or the inverting op amp has shorted input causing both channels to go dead when mono switch turned on. Not very likely.
Never heard of Amber, but respect the Made in Charlottsville, VA label. I tried to get a job in Staunton 38 years ago, ended up here instead.
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