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Used Affordable Power Amp Suggestions

ScooterMcTav

ScooterMcTav

I know less than I think
Hi All,

In tweaking with my McIntosh MA-6100, one thought I had was to try using it as a power amp as it is just missing "something". So, I thought hooking it up to something with some digital ins might not be a bad thing either.

The eBay Gods were good to me, and I was able to reasonably purchase a quite nice Rotel AVR (RSX-965) that had digital ins, pre-ous, and a phono stage to try out this experiment. All of my inputs were moved to the Rotel to use it as a pre, and the Mc was set up just to provide power.

Sound was kind of "meh". Some warmth disappeared, and I was duly underimpressed.

So, I tried switching things around, and rehooked all of the sources to the Mc, then used its pre-out to the Rotel power in.

Holy s*%#snacks!

The extra weight and authority picked up by moving the amplification offboard was immediate and palpable. Despite the Rotel being only 75WPC (vs 70WPC for the MA-6100), the sound was cleaner, had fuller and tighter bass, and was cleaner at low volumes. Apparently I like the sound of the Mc as a pre, but it must be a bit weak as an integrated.

Sometimes as audio fans, we try and talk ouselves into something sounding better (even if the improvement is marginal). However, for me this was one of those "a ha!" moments, when we easily hear an audible improvement in what we're listening to.

However, I don't have much interest in leaving a huge AVR (with "Tape 1" on its display) hooked up as a power amp, so was wanting to solicit opinion as to where there is good value in power amps. Budget will be a constraint, as I am in Canada, so am forced to buy US gear with $0.75 dollars.

Based on the Rotel experience, I am guessing 75WPC is a good minimum, unless you guys know something I don't about specific brands of power amps. I'd like to spend between $200-$250 US, though less is better.

I am familiar with Rotel (listening to an RX-600A as I type this), but am unsure about their power amps - they seem to sell for less than I'd expect on eBay. I've also seen lots of Adcom, Onkyo, Hafler, Integra, and a few different generations of Marantz.

A couple that have caught me eye are:
Marantz SM-500dc - Nice kind of retro chic, and vu meters, but is it really 100 WPC?
Integra ADM 2.1 - Affordable, 100 WPC, and Integra used to be good, right?
Rotel - RB951 - usually reasonable, but only 50 WPC
Rotel - RB1050 - a little more angry looking, 70 WPC
Big Onkyos, like the M-501 or M-5150 - look impressive but kind of ooze BPC

Never heard an Adcom, though research suggests I wouldn't be happy with one in my price range. Hafler also seems to have earned mixed opinion.

What say you A-Kers?
 
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You just found out that the signal frequencies are determined by the technical capabilities of a preamp. Name brand recognition is nothing as you just proved specifications do count. The point is equipment that reproduces the same frequencies that were recorded and not just some of them. Then it's silly to think that only one brand can do that...
 
Adcom, Emotiva. Outlaw Audio, Yamaha, Denon, HK...Your budget and availability will be what determines the choice. Personally, I'm rather impressed by my little twin transformer Adcom GFA-535L. A lot of people dislike Adcoms because they have no speaker protection, but Stereophile gave them a great review for sound quality.

BTW, has your Mc been serviced?
 
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I've used Crown amps in my hi-fi systems for over 45-years. Currently my favorites to drive nearly every speaker system I own are the PS-400 and PS-200. They can often be found in your price range. I also own Soundcraftsmen Pro-Power-Four, Carver, and Adcom, but the Crowns are my favorites. :dunno:
 
The Mc is a solid and quality piece (I am not a Mc fan, but respect them--just not my cup of tea). I do agree with others that perhaps it is time for a "tune-up"--can make a world of difference with any aging amplifier.

Another factor is "synergy"--you will see/hear that term bantered about quite a bit--here and on other forums, and IMHO it is a very real effect--some gear just "does not play well with others". Your Mc amp may not "like" your speakers and vs versa. The Rotel amp may pair better with your speakers--just something else to consider.
 
Thanks for the feedback guys. The Mc was serviced last year, but I should review the paperwork to see what exactly the previous owner had done to it.

One possible compunding issue is the mains, which are Soliloquy 6.2 - lovely sounding speakers, but they do require some juice to move them with their nominal 12ohm impedance and 89db efficiency. I wonder if this is the biggest gain, in that the separate amp placed a little less stress on the Mc. Not that the Mc alone sounds bad (it doesn't), it just sounded better with the Rotel added in.

And yes, I agree wholheartedly with synergy. Before the Mc I had a Musical Fidelity a3.2. Paired with the Soliloquys, it was enough to make one want to rupture their own ear drums. Simply ghastly.

Appreciate the suggestions though. A few more items to go look at on eBay.
 
ScooterMcTav said:
Yup. 12 nominal, 9 minimum.
Click to expand...
Hmmm . . . your MA6100 won't make a lot of power at 12 Ohms nor would it drive such speakers particularly well. Really, what you need is a SS Mc amp with autoformers with 16 Ohm taps. Here are some options that have both:

MC50s / MC250 / MC2505
MC100s / MC2100 / MC2105
MC2120 / MC2125

I realize that none of these are within the budget you're discussing, but any of them can be had at a good price if you're patient and would make an excellent upgrade from where you are currently. Personally, I'd buy and MC2300 and never look back but that's just me . . .

The proposition of purchasing an inexpensive direct coupled SS amplifier that would drive 12 Ohm speakers well would take a lot of trial and error.
 
damacman, I think you hit on what I was thinking - the 6100 just doesn't have enough juice for the job. I could literally hear the speakers open up with the use of the Rotel. However, I'm not sure I'd mail order Mc gear, and we have very few pieces locally for me to look at. Actually never thought I'd ever own a piece of Mc gear, until a fellow local audio enthusiast decided he was as unhappy with his 6100 as I was with my Musical Fidelity a3.2.

That being said, it looks like the Rotel of the early 2000s vintage might not be a bad fit based on the experiment already conducted, and budgetary constraints. At some point in my life, I will have the budget for all the lovely gear you detail, but that day won't likely come until we get the kids through University.

Maybe I can answer my own question, and keep the scope out for the right piece of min 75w/channel Rotel power amp.
 
And to tie a knot on the thread, a six-channel Rotel RB-976 just came available locally at a reasonable price. The six 60W channels are bridgeable into 3 x 150W into 8ohms. Should hopefully be enough power as I only need two of the channels. Can hopefully get the woofers dancing.
 
Well funny enough, the guy said the unit had volume problems, but he was unsure if they were with the power amp, or the preamp (RSP 980) that came with the power amp. The issue was apparent when I tried to bridge the channels. Switching the sections to stereo operation, I could test that both channels on the A system were working and were bridgeable, only one channel on the B system was working, and neither channel on the C was working.

A quick look under the hood revealed that the three channels were down as each of their output fuses were shot. Something shorted somehow in a very bad way - almost like someone decided to change speakers while the unit was on, or maybe a wild party ended up with speaker wires ripped out. Who knows. A little bit of dried brown crud is also under two of the caps by the power switch - doesn't look like leaking caps, but almost more like someone spilled a rye and coke by them.

Off to try and find some fuses today to see if we can get the item back up to speed. Very curious about the pre as well even though I was planning to eventually toss it - it's retail was $1,200 US back in the day.
 
And so I was able to source fuses yesterday to get the power amp up and running. Looks like the output fuses were the only issue, with them blowing likely being caused by the god-awful binding posts.

When testing the amp using each 60w channel independently, it was kind of meh. With the bridged 150W, it wakes up the speakers fantastically. Great value for a 150W/channel power amp.

But of course I needed to try out the RSP-980 preamp. AllI can say is it is really good. Less warm than the McIntosh's preamp section, a little more sterile and refined, and fantastically detailed. I now understand what people mean when they say "holographic" sound.

Not sure if I'll find it fatiguing over the long haul, but the Mc is now on vacation for a little bit.
 
I ran into a similar situation with a MC2100. even after gone through by Terry DeWick it just did not give me what I wanted from my Magnapan 1.6 QR's at the time. My thought's were the Autoformers on the MC2100? On the advice of Roy at Green Mountain Audio I picked up a Acurus A200 and have never looked back. I now run 3 of them. Lot's of current and run barely warm with any impedance. Look for a A100 or A200. The A150 and A250 have more grain and a cheaper build. FWIW
Regards,
Jim
 
Well maybe I spoke too soon about the Mc. Or maybe I needed to listen to a few more of my demo discs with the Mc and the fully functioning power amp before putting the Rotel pre in the chain.

Regardless, after putting some banana plugs on the speaker wires (the RB976 has the worst speaker terminals I've ever seen - I can see how the speakers could easily short), I gave it a more extensive listen.

And it appears my concern about fatigue was real. The mid-forward nature of the sound with the Rotel was detailed. And tinnitus inducing. When I started to think about hooking up an EQ, I figured it was time to try the Mc again.

Listening to a couple of the songs where I had a wow moment with the Rotel, and it became apparent the improvement in dynamics was very much a product of the power amp. Except with the Mc, the mid is dialed back just enough to keep it listenable.

The pre is obviously an extremely good piece of gear - just a little too hot for my mid-forward Soliloquys.
 
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