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  1. #1

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    Default I need help trying a power amp

    Just getting into this stuff and I have an opportunity to jump on an Acurus 250 power amp but I have no way of testing it. The owner is pulling it out of storage and has no preamp to try it with. Problem is, I have no preamp either. Is there another way I can test it audibly without a Preamp to see how it works? Can I use a receiver? I don't know much about multimeters, etc. Thanks.

  2. #2

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    You can hook up a cd player. And some speakers of course
    It's better to burn out, than poop your pants


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    You can use "any" receiver IF it has PRE-OUTS on the back! Do you have one of those.

    Another way to do it is if you have a source, like a CD player that has "variable" L/R outputs and a gain or volume control of some kind on it. In this case you can hook up the CD player directly to the power amp and wire the amp to the speakers and have some control of the loudness. It might not be SUPER clean but it will give you an idea of if there are any "major" problems?

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    A TV with variable RCA outputs could also work. Make sure the TV volume is set to zero before turning on the amp.
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    How about you phone using a headphone jack with RCA terminals and control the volume with the phone.

    Make sure the volume is at zero and connect the phone before powering the amp.
    Can this work....

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    Hope I don't sound like an idiot, Brusco, does the owner have any idea how long the amp has been sitting in storage? Electronics have a funny way of popping caps when powering up if it's been many years. This is where a variac can come in handy for a controlled power up.

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    Quote Originally Posted by Irrenhaus View Post
    How about you phone using a headphone jack with RCA terminals and control the volume with the phone.

    Make sure the volume is at zero and connect the phone before powering the amp.
    Can this work....
    A phone doesn't have the line voltage to drive an amp.

    Bring a receiver that has preouts and a couple rca cables to hook it up. You could also use a cdp as long as it had volume control. Without any volume control it will be full blast audio.

    Now, personally I'd shy away from this. Any seller should give a buyer a way to confirm it works. Just sayin' is all.

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    Quote Originally Posted by tonyb View Post
    A phone doesn't have the line voltage to drive an amp.

    Bring a receiver that has preouts and a couple rca cables to hook it up. You could also use a cdp as long as it had volume control. Without any volume control it will be full blast audio.

    Now, personally I'd shy away from this. Any seller should give a buyer a way to confirm it works. Just sayin' is all.
    I stand corrected thanks tonyb....
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    I had tested an amp using a 1/8" stereo plug to RCA cable and my Droid phone and a pair of small speakers. It happened to be an Acurus 100-3. I know this is not ideal but if you have nothing else it will work. By the way, the Acurus 100-3 was a very sweet sounding amp. I only passed as it was known not to handle low impedance very well and the price was too high. The A100-3 was beefed up to handle low impedance.

    Bring a good DVM if you have one available to check the dc offset at the speaker terminals before connecting speakers. Before the guy offered me the Acurus, I had gone there to look at a Hafler 220. One channel had a big dc offset so I passed on that one too.
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    Quote Originally Posted by Polkie2009 View Post
    Hope I don't sound like an idiot, Brusco, does the owner have any idea how long the amp has been sitting in storage? Electronics have a funny way of popping caps when powering up if it's been many years. This is where a variac can come in handy for a controlled power up.
    ^^^^^^
    This +1
    Electrolytic Capacitors are not like fine wine, they don't get better with age.
    Sitting un-used for years is bad for Electrolytics.
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  11. #11

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    I Concur... I pulled this Kenwood KR5150 out of the shed. Woohoo It has the PREOUTS! Inside's not looking too pretty. I plugged speakers into the KR5150 alone to see if it's working. The Left channel on the KR5150 is weaker than the right. Should give it a good over with DeOxit?
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  12. #12

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    Plan B i guess. I have a CD recorder that has analog outs and headphone volume on front. 1/4" out to rca > power amp?
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  13. #13

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    You will be able to drive the amp with the headphone jack on your smart phone, just not to full power. Personally, if the DC offset looks good & the amp prduces sound when powered by your phone, it's probably fine.

  14. #14
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    Quote Originally Posted by Irrenhaus View Post
    How about you phone using a headphone jack with RCA terminals and control the volume with the phone.

    Make sure the volume is at zero and connect the phone before powering the amp.
    Can this work....
    This does work, and I often use my iPhone with 1/8" to RCA to test amps and preamps.

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    Quote Originally Posted by DaveHo View Post
    You will be able to drive the amp with the headphone jack on your smart phone, just not to full power. Personally, if the DC offset looks good & the amp prduces sound when powered by your phone, it's probably fine.
    True, and that maybe ok to see if it powers up but why test a quarter of the amp ? You won't get any clue as to how it's suppose to sound which I think is the whole reason for buying one to begin with. Maybe it crackles at higher volume, maybe it shuts down under a heavier load, who knows. Getting the amp home after testing with a cell phone and finding out it sounds like arse doesn't do you any good. Unless you need a new boat anchor.

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    This is why I have an android phone with voodoo mod - can output insane levels of clean signal. Preamp is the best way but in a pinch my Galaxy Infuse works very well playing flac at full volume. I just never use it as a phone!
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  17. #17

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    No smart phone here. It will have to be the headphone preamp on my CD recorder. ok thanks everyone.

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