Hi fi Amp for Studio Monitors

Which model are they? Also do you have a soundcard for the Mac Pro?

Also what will you be using them for? Are you just listening to music or are you recording/mixing racks? If the latter you probably want to go for a studio amp.

And finally what's your budget?

Something like this:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=310-312

might work for you, depending on your power needs. It's got a USB DAC built in, and the form factor is hard to beat for convenience.

The little Tripath T-amps have a good reputation. I've been using a cheaper but similar amp and it's been quite good to me for desktop listening. If you search around for t-amp you'll find a lot of options, both more and less expensive.

What are the output options?

I'd run least 150 watts rms a channel through those. I'd be looking for an older power amp with around 200 -250 watts a channel power.

mitoman212 said:

Thanks for the suggestion unfrotunatly that amp wouldn't be able to power my speakers as they need something around 150 watts rms.

But thank you! This amp might work for another set I have lying around.... to many speakers in my house lol

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Too many speakers... I hear ya.

Just FYI -- you don't need to run the maximum rated wattage through a pair of speakers. Sometimes people think that speaker power ratings need to be matched to the amp; the speaker's power rating is more of a "don't go above this" rating rather than something which must be matched exactly.

Your monitors can handle a lot of power, but a quality 20 watt amp could make them sound great. The tradeoff of course would be that a bigger amp could get louder. And depending on the listening levels, you might not ever draw anywhere near the maximum. In typical home situations, you're only drawing about 1 watt from an amp at any given time, though peaks rise well above that.

I use monitors which can handle 100 watts, but since I'm running them nearfield I get by fine with a 15 WPC amp -- it's actually painful to turn it up more than halfway, and I don't get anywhere near clipping the amp.

Anyway, if you want the headroom or you like it loud, by all means get the bigger amp. Just saying that using a smaller amp isn't a problem in and of itself.

Wattage is very overrated.

100 watts provides twice the volume of 10 watts

1,000 watts provides twice the volume of 100 watts.

mitoman212 said:

My question is what would give me the best sound reproduction? Would it be best to get an amp marked as Hi Fi or one of the amps that has a USB input with its own card?

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That'll depend mostly on the design and how well it was executed. These days even very inexpensive amps can sound quite good.

These speakers cost around $5 grand new for a pair I'm sure mine aren’t worth near that anymore but they are really high quality monitors even though they are old I just want to use them how they were intended.

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They're definitely high-end; your choice of amp will have far less influence on the sound.

I was under the impression that using an optical input would give me the best sound quality, I'm probably mistaken tho.

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Optical and USB should be equivalent -- they both carry the same information. If you used the analog outputs you'd be using your computer's converters, but they would still probably be good; I'd only be worried about noise and interference in that scenario, and Apple typically does a decent job in my experience (unlike some of the PC's I've previously owned, where the analog outputs were unusable).

I reckon the amplifier is of vital importance.

Underpowering an amp is not a good idea. You are far more likely to burn out a voice coil using an underpowered amp, because once the low powered amp reaches a point where it can't output any more power, it will start outputting DC current.

I'd quite happily run a 250 WC amp with bookshelf speakers rated at 80 watts.

What is yout budget OP?

You could pick an 80's power amp like the Yamaha M series, Onkyo Integra M series or Kenwood basic M series. Maybe a larger NAD integrated or power amp?
Carver mono blocks? Save up and get a second hand larger Bryston?

For a DAC, i'd suggest the old fw400 Apogee Duet that should be available second hand for $200-300. this is a brilliant DAC.

mitoman212 said:

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I had to replace the midrange due to the suspension being rotted. However I couldn’t afford the $250 each for the stock driver so I put in a replacement. Not sure if there is a better option the midrange didn’t really fit the box but it sounds better than the old one. My budget is pretty low but I am interested in it so will be setting money aside as I can.

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THen why not simply replace the suspension. It s an easy job. Cheap too, you can have it done for $30 or DIY for the cost of the parts.

With a random replacement that only "sort of" fits you have totally eliminated the possibility of "audiophile" quality sound from these. I'd repair the old driver and swap it back in. There is a LOT more to choosing a new driver then just if it fits in the hole.

If you need an amp the best bang per buck for your needs right now is the AMPP100 by Audiosourece. It's a pretty good amp and not expensive.
http://www.amazon.com/AudioSource-AMP-100-Stereo-Power-Amplifier/dp/B00026BQJ6

You can conect the "line out" from the Mac to the "line in" on this amp and be on the air for under $100.

One More Thing: If you care a lot about the sound, first thing about the listening area. NOTHING matters more then the greenery of how this is set up, the placement of the speakers and you and the distance from the walls and acoustical properties of the room To mmany beginners ignore this and simply buy equipment and wonder what's wrong. In order of importance to sound quality you have:

1) the room itself and the placement of the litenter and speaker in the room
2) the kind and brand of speaker
3) the amplifier

Also once you get to a certain quality level the difference in sound between amps is subtle, at least.

In your case, (1) think abuot the listing area, do as best you can to kill early reflections and so on. (2) fix the old driver. (3) order a moderate size amp for $100 or less. (4) buy the CORECT cable, no adaptors get a 1/8" TRS to dual RCA cable.

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quasinormal said:

I reckon the amplifier is of vital importance.
..
What is yout budget OP?

You could pick an 80's power amp like the Yamaha M series, Onkyo Integra M series or Kenwood basic M series. Maybe a larger NAD integrated or power amp?
Carver mono blocks? Save up and get a second hand larger Bryston?

For a DAC, i'd suggest the old fw400 Apogee Duet that should be available second hand for $200-300. this is a brilliant DAC.

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What is the OP's budget. I could not afford to replace a $250 driver.

Why bother with a external DAC. The one build into the Mac is very good and he will NOT hear the difference on a "hacked" monitor. He has some random driver in the box the dose not even fit in the hole exactly. You really think a $300 DAC is going to improve that?

OP, go to the audiokarma forums to the "digital audio" section and there will prboably be a bunch of similar threads there.


for listening, i run my output through a tascam DAC (was like $100 or something, i got it mostly to record vocals and guitar) out via AUX to a late 70s technics receiver that I got on craigslist for $50.

Also I would imagine whatever soundcard a mac pro has probably has a good DAC on it so you'd probably be ok with line out.

quasinormal said:

Underpowering an amp is not a good idea. You are far more likely to burn out a voice coil using an underpowered amp, because once the low powered amp reaches a point where it can't output any more power, it will start outputting DC current.

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Sadly, no, this "clipping outputs DC" is a persistent myth. Can clipping cause damage? Yes. But not this way. This myth is propagated by people who think that a square wave has flat parts, so it must be "DC for a short period of time". This is just a straight misunderstanding from a Fourier analysis point of view. I don't think this is the forum to get into the details, but it's been discussed to death on <put your favorite enthusiast forum here>.

Basically, if you don't push the amp into clipping, you don't need to worry about it.

Anyway, +1 to good advice from ChrisA and mjn.

SteppingStone said:

Sadly, no, this "clipping outputs DC" is a persistent myth. Can clipping cause damage? Yes. But not this way.

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Good eyes. I only read the part about how an underpowered amp can "clip" and figured it was right. ANY amp will clip if you drive it hard the only question is "when". (It is almost exactly the same as with a car. ANY car has a maxium speed on level ground.)

But I stopped reading before I got to the "DC" part. In order for that to happen the amplifier would have to be broken in some very uncommon way that just never happens. Actually when a sine wave is clipped (made flat on top) the clipping introduces a lot of high frequency power in the form of odd harmonics. exactly to opposite of DC.

Yes people have blown tweeters using a low-end amps. As I said the clipping process puts power into higher frequency and if the tweeters are sensitive they are at risk. But this is not common and just is not an issue here, not with these speakers and the AMP100 or one like it. Just don't worry about it. THis WAS an issue when peole used those big 1970's vintage low sensitivity (say 81 dB/W @ 1M) speakers with a low-end 25WPC transistor amp. But today such a mis-match is uncommon.

The high power amp can blow up speakers too, simply turn it up loud and run it a while and you basically melt the voice coil the woofer. So you are doomed either way if you go with an amp that is either way to big or way to small. The "safe" thing to do is buy an amp that is reasonably matched to the speakers and the intended volume level. The AMP100 at 50WPC is about right.

The other option is to use a vacuum tube amp. They don't "hard clip" But I assume this is not a reasonable option in this case.

The high power amp can blow up speakers too, simply turn it up loud and run it a while and you basically melt the voice coil the woofer. So you are doomed either way if you go with an amp that is either way to big or way to small.

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With one minor caveat: if you go with an amp which is way, way too small (e.g. a 12 WPC amp on a speaker with tweeters rated for 25 watts) then you're probably safe as well. Even under massive clipping, the amp just can't put out enough juice to exceed the tweeter's power handling.

Not disagreeing with anything you recommended, BTW.

I upset some audiophiles.

I will leave any advice on underpowering speakers in the future to the experts.

quasinormal said:

I upset some audiophiles.

I will leave any advice on underpowering speakers in the future to the experts.

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No. You upset some physicists. Most "audiophiles" would believe the part about DC current and argue that Joseph Fourier was wrong.

But you are right about some small amps being able to blow speakers. Usually it is the tweeters that get blown.