Mid-Fi Power Amp Comparisons

daddyjt

F1nut wrote: »

slbenz wrote: »

I would recommend having the MKII opt2 upgrade done to your amp. Will take it to a whole new level and more than double the output while making the amp sound more refined and life-like.

It should be noted that Mr. Carver does not approve of that mod. Something about overtaxing the power supply, IIRC and I know I've seen comments about some of the modded amps failing.

Bob (Carver) spent a good deal of time with a mkII opt2 M1.0t at Carverfest this past year, and absolutely loved it. He was impressed with the engineering behind the modification as well.

It should be noted that much of the actual modification is derived from the Carver TFM55(x) amp, which shares much of the same topology as the older M1.0t. The mkII opt2 achieves its increased power by increasing the rail voltage, and increasing the voltage handling capacity of the parts in the entire chain down stream.

If you were to sup-up the engin in a '60s muscle car, then beef-up the transmission, drive line, differential, tires and breaks, would you still say "there's no free lunch"?

I've been running a pair of mkII opt2 M1.0t amps on a pair of Infinity Kappa 9 speakers (a FAR more difficult load than ANY Polk) for a couple of years now, and I push them HARD. I have had zero issues - none. As with anything of this nature, there are hacks out there performing the modification. If you stick with Greg (nahash5150) or Wayne (wrf) on the carver site, you'll be fine. The warranty their work, and they are booked out for a year... That should tell you something.

OldmanSRS

jdjohn wrote: »

I would interested to get opinions and sound characteristics on these mid-fi power amps for driving SDA-2Bs.

Adcom GFA-555
Carver M1.0t
I have the Adcom 555 already and a Carver 1.0 in-transit. I have read that the Adcom is bright, and I can't disagree with that so far. I've read that the Carver might be warmer, but will find out soon enough.

I have a TFM-35 and an M10.t they have run SRS1.2's and 2B's They are indeed consistently warmer, due to IMO, the bass end. The highs are good but they sound a little loose in the bass control. They have a 9 damping factor and they are supposed to emulate tube amp sound...

My GFA555 has been modded by (me) and Musical Concepts and comparing it to a non modded 555, it's tighter and more dynamic. I prefer listening to it over the Carvers. I prefer the non modded 555 over the Carvers as well. Some speakers might like the Carvers better if they lack bass or like less damped woofer movement.

littlewoodboats

I am with OldmanSRS on this one. Rick at Big Sky Audio did a full rebuild/modification on my GFA-585se and the last word I would use to describe the sound is "harsh".

No idea what your budget might be but here is the page with info on your amp. Rick works by himself so does not normally answer the phone but does answer his e-mail. He could tell you what the changes in sound might be with the new parts.
http://bigskyaudiomt.com/index.php?pr=ADCOM_GFA_555_II

Timothy Smith

I have owned most of those amps and would personally rank them as follows from best SQ to least:
1. PS Audio Delta 250
2. Sumo Andromeda (two different examples)
3. Parasound 1200
4. Rotel RB 1080
5. Adcom 555 (two)
6. Carver TFM-35

jdjohn

Thanks for all the latest input. Lots of good discussion on the mods of the various amps, and Timothy has thrown some new players into the discussion. I assume those are all common ground?

I got the McCormack working tonight. Turns out it was sloppy soldering on the big black replacement resistors(?) in the attached pic. Looks like those are coming from the RCA input jacks. I noticed that these were a bit loose, and when I looked underneath, the left channel in particular had crappy solders. I added a bit of new solder, and it worked! You can see in the pics of the underside how the solders in the upper right (left channel) and bottom left (right channel) are kind of ugly. They're still ugly after my touch-ups, but they work. I'm sure they broke loose during the shipment since they were marginal already, and the cold temps during transit didn't help. I may still take the amp to a tech to let them clean up those connections (and any other suspect ones). Any tips on how to clean them up better myself? Anyway, glad I got it working without any additional cost, and now I can keep it

Time to start doing some serious comparisons. One design difference I've noticed is that the McCormack is the only one with a removable power cord, and it's the only cord that is three-pronged. I've also noticed that the B&K gets pretty hot compared to the others.

tonyb

The B&k should not be running hot. That might be an indication of the bias needing to be adjusted. Glad you got the McCormack up and running. Steve McCormack himself says his amps respond very well to upgraded power cords. Something to think about should you decide to keep it.

slbenz

daddyjt wrote: »

F1nut wrote: »

slbenz wrote: »

I would recommend having the MKII opt2 upgrade done to your amp. Will take it to a whole new level and more than double the output while making the amp sound more refined and life-like.

It should be noted that Mr. Carver does not approve of that mod. Something about overtaxing the power supply, IIRC and I know I've seen comments about some of the modded amps failing.

Bob (Carver) spent a good deal of time with a mkII opt2 M1.0t at Carverfest this past year, and absolutely loved it. He was impressed with the engineering behind the modification as well.

It should be noted that much of the actual modification is derived from the Carver TFM55(x) amp, which shares much of the same topology as the older M1.0t. The mkII opt2 achieves its increased power by increasing the rail voltage, and increasing the voltage handling capacity of the parts in the entire chain down stream.

If you were to sup-up the engin in a '60s muscle car, then beef-up the transmission, drive line, differential, tires and breaks, would you still say "there's no free lunch"?

I've been running a pair of mkII opt2 M1.0t amps on a pair of Infinity Kappa 9 speakers (a FAR more difficult load than ANY Polk) for a couple of years now, and I push them HARD. I have had zero issues - none. As with anything of this nature, there are hacks out there performing the modification. If you stick with Greg (nahash5150) or Wayne (wrf) on the carver site, you'll be fine. The warranty their work, and they are booked out for a year... That should tell you something.

I can vouch for Wayne (wrf) for the work he did for both my Carver M-1.0ts, Carver M-500t, Carver C-1, and Carver C-9. All of which works perfectly and the workmanship was first rate. Luckily he is only 20 minutes from my house. Great guy.

11tsteve

That third pic looks like the trace is damaged.

Nahash5150

F1nut wrote: »

slbenz wrote: »

I would recommend having the MKII opt2 upgrade done to your amp. Will take it to a whole new level and more than double the output while making the amp sound more refined and life-like.

It should be noted that Mr. Carver does not approve of that mod. Something about overtaxing the power supply, IIRC and I know I've seen comments about some of the modded amps failing.

I'm not sure where the 'non-approval' comes from, but he's never voiced such a thing in my presence. On the contrary, there is a YouTube video from Carverfest 2009 (I think?) where he displays no concern whatsoever for the modification. He's had an M1.0t mkII opt002 in his hands (2013) and I explained all of the features of the mod, and all he said was, 'wow, he (Rich) did everything right'.

I've never asked for Bob's 'endorsement' because it's really not necessary. The amps perform just fine, and if it weren't for the bump in rail voltage, which is still very small in comparison (10% increase) there would be no fuss about this modification at all (at least on a technical basis). It's just a glorified repair/refurb that brilliantly upgrades the performance of the amp.

Rich has been doing this mod since 2008, and I have taken over the project (and thus, all of his repairs) for the last two years and have received a total of 2 amps during that time that needed repair (both repairs were small stuff - blown resistor, etc - they are vintage amps after-all). I have NEVER seen one where the power supply failed. So this mod has an 8 year record of proof that the rumors of power supply failure are false.

I should note however, that Russ Kall, who was doing the mod for several years, used inferior part - some of which turned out to be counterfeit, and that must be the reason for most of the recorder 'failures'. Some of my partners and I still get Kall amps that are indeed failed - at the output though, not the power supply, mostly due to extremely cheap **** parts. Well, those of us who honor a lifetime warranty use the best parts we can find, and they don't fail.

So even when the modification is performed by an amateur, with inferior parts, one cannot brick the stalwart (and underrated) power supply of the M1.0t (or M500t for that matter).

So to the point, while the mkII does increase the power rating and longevity of the amp, it also increases its value significantly. So even if you don't find the M1.0t or M500t to your tastes, you can sell it and 'upgrade' to a Sunfire or other entry level hi-fi amp which often cost over $1000 (unserviced!). In addition, if you own an mkII, you'll never pay labor for a repair - ever. And I'm confident claiming that because guess what - my bench has no repair backlog for mkII amps whatsoever, but I'm 18 months out for stock upgrades and repairs!!!

Cheers!

halo

So, how do you like the McCormack DNA 125 @jdjohn ? Which of the amplifier(s) did you end up keeping?

jdjohn

halo wrote: »

So, how do you like the McCormack DNA 125 @jdjohn ? Which of the amplifier(s) did you end up keeping?

I like the McCormack very much...best of the bunch. I actually still have all five of the amps right now. I got side-tracked with some tt's that I rescued from my dad's garage, so it has kept me too busy to try and sell any of the amps yet, but I have the McCormack hooked up for daily driving.

I had a little write-up prepared reviewing all of the amps, but I lost it due to a computer system restore I do plan on recreating it, though.

tonyb

I knew you'd like the McCormack. Looking forward to your review anyway.

BTW....you saying that all amps don't sound the same ? Blasphemy....LOL

halo

I'm glad to hear that you liked the McCormack.

I just purchased a un 8 year old, pre owned, DNA 125 and I'm picking it up tomorrow morning. Bob Backert of RHB Sound Dezign upgraded the signal path caps (Black Gate) and power supply.

Given all the positive comments surrounding this amplifier, I am eager to get it into my set up.

I will, eventually, be looking to add a preamplifier as well. Possibly a Peachtree unit that will accommodate my digital, PC based, media server as well as the analog outputs on my Pioneer SACD.

tonyb

Is that the same Bob Backert from Backert Labs, who we are doing the demo round of the Rhumba with ?

Interested in hearing your thoughts too, so by tomorrow, 3pm ? lol

halo

tonyb wrote: »

Is that the same Bob Backert from Backert Labs, who we are doing the demo round of the Rhumba with ?

Interested in hearing your thoughts too, so by tomorrow, 3pm ? lol

lol. I didn't know that when I bought it, but it looks like it. That's pretty

Unfortunately, I don't have a dedicated preamp in house, just the Marantz NR1402 with a set of pre-outs for the front speakers. I don't think that this is going to give a great impression of the amplifier's true potential or sound signature.

Any of the Illinois Polkies want to stop by Chicago with a pre for a listening session?

We can wait until I get the UniFi UB5 speakers in house and compare them to the RC10 and/or the RC70 speakers as well.

Oh, ya, it's a little chilly today so I'm going to have to let the McCormack acclimate before I can hook it up.

erniejade

If I had more time, I would bring the Joule 150.

halo

erniejade wrote: »

If I had more time, I would bring the Joule 150.

I'm in no hurry. They had the amplifier inside at my local FedEx since yesterday so, no need to wait for it to acclimate!

Got it hooked up and I am running pure direct through the NR1402.

Thus far, I am very impressed. First disc spinning on the Pioneer is Fiona Apple's The Idler Wheel Is Wiser Than the Driver of the Screw and Whipping Cords Will Serve You More Than Ropes Will Ever Do.

Her vocals are wonderful. She's right here in the room with me. It's haunting. So many layers and details in this recording brought to life with authority. This CD sounds good through the Marantz but it was a bit sloppy in the low end. When the funds allow for it, I'll be looking to add a separate preamp into the set up. Like I mentioned earlier, I may be looking for a Peachtree pre/DAC to control the Pioneer and the PC media server. I still have my SB3 so I may play with the idea of running it through the Micca OriGen DAC or through the built in DAC on the Peachtree.

There are other preamps that I have my eye on but the lack of funds has me window shopping for now.

The DNA 125 is really amazing. The amplifier runs very cool to the touch as well. I was very sad the day that I had to sell my Sanders Sound System ESL amplifier. I'm happy that I came across the McCormack brand and the reviews here on the forum. I don't think that it's an apples to apples comparison between the two but I do like what I'm hearing with the McCormack.

Cheers everybody and my apologies to the OP for the sidetrack.

halo

Oh, I am using a super beefy signal cable power cord with it as well as signal cable speaker cables and analog II interconnects between the Marantz and the McCormack.

I had that stuff left over from my previous hi-fi set up with the InnerSound hybrid ESLs so I dusted it off and got it all connected.

Today is also my first day of spring break. Sadly, I only have a week off

tonyb

Nice bro, the Sanders is no slouch by any measuring stick either. The thing I also like about McCormack amps is their sound signature doesn't change as you move up the chain. You just get more of it. You could be happy though with that puppy for a very long time. I would love to hear Ern's Joule mated to it, I think it might be a match made in heaven.

halo

erniejade

Nice!!!!

halo

erniejade wrote: »

Nice!!!!

Thanks It's a man's amp for sure (it's not going to win any beauty contests - it's all business).