2. amps-preamps
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Amp newbie? Adcom GFA-555 vs Mcintosh 2505

Hi I'm definitely a newbie, and already know my initial choices in starting my first adult sound system will make experienced folks around here cringe...but I'm wondering if I might still garnish a bit of insight to help reduce additional "bad" choices or steepen the learning curve just a bit.

From the beginning; I went and auditioned speakers at Best Buy, and of course fell in love with Martin Logans...and decided to order a pair of Magnepan MMGs (not a bad start right?). Did some research and bought a HK3490, maybe not the wisest choice...kind of wish I had started with separates...but it should be able to handle the MMGs...I know I amjumping the gun a little because I have not even heard this combo due to some shipping issues with Magnepan...but my question is this...I'm thinking I can use the HK3490 as my preamp and add a separate amp?

And the real question how do you compare amps...I am looking at a few intro. affordability choices like the Adcom GFA-555 rated at 200w/channel vs. the Mcintosh 2505 rated at 50w/channel...but I'm under the belief it's not just the watts, but the amps that are driving them...otherwise my HK3490 at 120w/channel should have the juice to power the maggies...so how do I know which will deliver a better sound for the buck...and more importantly...how many watts do I really need?
windhorze
10 responses Add your response
blindjim
3,092 posts
 
I'll take a shot here and suppose the Maggies are monitors, not panels, right? Also that their impedance is above 4 ohms, right?

If so, then perhaps first things first... connect them (when they arrive) to the HK.... and go from there.

True, there are watts and then tere are WATTS, but the speakers needs for power and control as well as the room they're in pretty much determine what size amp should push them... your preffs will deteremine which size amps 'voice' will do it for you.

If you have preamp outputs, sure, another amp can be added/used instead of the rec's amps. As much as I'd probably prefer the Mac over the Adcom, the 50wpc bothers me a lot... but does depend on how much volume you want to get out of the speakers... and that's where your preffs and the room size comes into play.

I think the bulk of SS amps range around the 150 - 250wpc mark. Almost every amp maker out there makes one in that area. having one on hnad which has the numbers allows you more flexibility with speakers... and usually, only less power damges them, not more power.

Take you thesis a step further... a Krell KSA 50 OR LEVINSON ON THE SAME ORDER, SHOULD BE STILL MORE ADEPT THAN THE MAC...

Try the HK and go from there. Odyssey makes some great sounding amps and are routinely traded here for reasonable rates.
drumhead4
20 posts
 
You want to look at the specs for the rating at 4 ohms. This will give a clue as to the size of the power supply. If the rating from 8 ohms to 4 ohms doubles then you have very high current which what Magnepans need.
dilly
113 posts
 
Based on my preferences with the benefit of doubt to system synergy I would say Mac...mac...mac.

You can visit Audiokarma Mac forum to get a better idea on this particular amp. Good luck on your search & hope the learning cuve would be steep! Cheers.
bwp
114 posts
 
I think your HK will be fine for pushing the MMG, I would see how you like it before pulling the trigger on a new amp. Magnepans are actually an easy load for amplifiers due to the fact the that are purely resistive, none of the wild impedance curves typical of box speakers. If it turns out you really like planars then you will probably upgrade to the 1.6s at some point, that is when you will really need to upgrade your amp.
prpixel
876 posts
 
The mangepans are planars with a nominal 4 ohm load.
jult52
155 posts
 
Wind - I'm a relative newbie driving MMGs with a 200w (360w into 4 ohms) ss power amp. I think mine (a B&K) does the job well (smooth, warm sound) but haven't done the comparisons to have an informed opinion. I took a similar route as you with preamps and began by using the preamp output of a Rotel integrated. I am happy to have an e-mail discussion about this since we are in a similar boat, but 2 comments: 1) the preamp selection is very, very important; 2) MMGs are great. You are going to love them long time.
windhorze OP
1 posts
 
Thank all for your responses so far....as far as some additional concerns... Drumhead- HK3490 is rated at 120 wpc at 8 ohms, and only 150 wpc at 4 ohms, this was my first concern (although their literature says it is stable at 4 ohms)...and Bwp- yes, I am already eyeing some of the used 1.6's around here...and yes the final concern...I have a slightly addictive personality and I see potential problems down the road...is there an audiophile 12 step program in the LA area by any chance? ;-) I might need an intervention!
blindjim
3,092 posts
 
Windhorze

Power ratings of receivers won’t usually double when imp is halved… as some other amps will. That doubling down aspect is no reason to reject an amp either.

RE Audio 12 step

First things first…. Place a greater priority on what you have, rather than what you desire. It’ll always work itself out. Always. One day at a time.

Turning off the personal confuser and listening to your system will help immensely too.
hifitime
715 posts
 
I wouldn't push the volume too much on the HK. It only consumes 310 watts max.That sounds like they may be giving it a higher power rating than it can really give out.Be careful until you get a quality power amp capable of driving 4 ohm loads all the time.Maybe start a new thread asking for the best sounding lower price amp to buy for the Magnepans.Stating a price limit will help too.
kqvkq9's avatar
kqvkq9
120 posts
 
The receiver should be fine with the Maggies. While Maggies do like a lot of power, those are small ones. You should be okay there.

Now when you go off the deep end for bigger ones, which you will, it's nice to have preamp outs on the receiver so you can just sub in another amp.

The Mac at 50 wpc is clearly not going to have the power for bigger panels.The Adcom, nah. I've found that while Adcom preamps like the GFP 565 can be really nice, the amps tend to flat and boring. I'm overgeneralizing there but there are a lot of used power amps out there. Enjoy what you have for a bit before you join the amp of the month club.

Your newly found sickness, and that's what it is, is not easily cured.Best of luck there. Remember though, you could be drinking, gambling, or chasing Women...
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