I need to reduce the number of components to accommodate a smaller rack. Room size is 15 x 20 x 9ft. Currently using Arcam P1 monoblocks (175wpc @8ohms) with an Arcam AV8. The system is used for stereo listening and video. Speakers will be Ohm 1000's.
The preamp output impedance of the AV8 is 25 ohms. To obtain satisfying dynamics at low volume I want an amp with as much, or more power than the P1's.
Which SS amps should I consider that will pair well with the preamp section of my AV8? My budget is 2k, and recommendations for used amps are fine. Thanks.
Dante, For the smaller OHM 1000s, I think you have many very good options that would appear to match well to your pre-amp and outperform the Arcams:
Musical Fidelity A3CR $600-$700 used this is what I am using and can voutch it sounds great with the OHMs and it provides plenty of power and current for my OHM 100.3s in my 12X12 room and does a hard to fault job even with OHM 5s in a much larger 20X30 L shaped room (my largest).
Other larger amps I have seriously considered (more for the 5s in the larger room than the 100s):
Wyred 4 sound st/sx/250 - should be within your $2000 price range
Audio Research D400 mkii - one up for sale here currently that has caught my eye
Musical Fidelity A308CR (one up here currently by a local to me seller that I have considered)
Musical Fidelity A5CR - step up from my current A3CR
I also like Classe amps for use with SS pre-amps in particular though I cannot suggest the Classe models to consider in your range without further research.
Mapman, Bob, Maddoggy, and Butcherboy, Thanks for your responses and recommendations.
Bob, I am not an expert. I was under the impression that one of the benefits of having a lot of power improves dynamics. (Of course, if it's not on the original recording, that's another story.) Also, I have been following the discussion on the thread re Ohms over in the Speakers forum, and I seem to recall that the Ohm's perform best with a lot of power. This was the basis for my statement. My musical taste is very broad-I enjoy almost everything but rap. Also, I do not not listen at very loud levels, except for some rock (The Who, Led Zep., etc)
I believe it is true in general that you need more power to make the OHMs sing, but there is more to it tha that. Not all watts are created equal nor are all OHMs equally power hungry (though they are largely as a group). Some additional qualifications are needed
Here are the technical factors I know of that matter in selecting an amp for the OHMs:
1) input impedance. This is more of a factor with tube preamps which tend to have higher inherent output impedances in general than SS. Lower amp input/preamp output impedance ratios will theroetically tend to negatively affect low end (bass) performance and perhaps other areas as well. How much difference you might hear based on this spec alone is debatable, but higher is generally safer
2) watts. In general more watts will go louder but that is about all this alone assures.
3) amps - in general higher current delivery will enable the amp to take better control of the driver at any listening volume enabling better macro and microdynamics
4) efficiency/power delivery into 8 4 and perhaps even 2 ohms (power rating mostly doubles into these loads). Amps that do this better in general should be able to drive the OHMs consistently at various frequencies and deliver a more balanced sound even at lower volumes
5) Damping factor. This is the similar impedance matching issue but now from amp to speakers. Higher damping factors are generally considered better. If it were me I would avoid amps with less than 30:1 damping factor into 8 ohms unless there is an opportunity to listen first. Above this, I would not let this sway me, although in general higher damping factors should lead to tighter, more controlled bass, all other factors aside.
6) I have the biggest and hardest to drive OHMs (5s) and the smaller 100s. My Musical Fidelity A3CR amp at 120w/ch into 8 OHMs deos a very good job driving both, but has to work much harder for the 5s. In a good application (OHM is matched well to room size), I think there may be diminishing returns with 100s with more powerful amps than what I already have. I believe the larger OHMs in bigger rooms, like the 5s, can benefit from an amp that can deliver a well matched 250w/ch or even more.
BTW, I've had the big OHM5s in my smaller room where the 100s normally reside as an experiment and found no advantage soundwise there. In fact, the 100s worked better because they are smaller and had more room to breathe. Fitting the OHM to the room correctly is the other very important thing to consider beyond amp selection and such.
"In general, I'm a fan of more watts. They just don't help at low volume."
#4 above (efficiency into 8, 4 and perhaps even 2 ohms) is the main factor I have found that makes the biggest difference in regards to sound quality at lower volumes. You might not hear much difference at low volumes between a 60 w/ch amp and a 250w/ch amp at low volumes if they both do this well. #2 (Watts/Power) is probably the one factor out of these that is not a significant factor at lower volumes. Everything else can make a difference I believe.
BTW, I checked the specs on your Arcam amps, and it appeared to me that you can do much better in this regard as I did as well in my case, only in your case you might not benefit from more than 120w/ch, unless your goal is to go louder and cleaner than currently as well.
In my case specifically , I found my current 120w/ch Musical Fidelity A3CR does low to moderately high volumes (at which I mostly listen) much better than my prior 360w/ch Carver m4.0t, and the difference can be heard with all my speakers (OHM 5s, OHM 100.3s, OHM Ls, and Dynaudio Contour 1.3 mkIIs) which is why I made the change to 1/3 the watts I had prior. The Carver definitely went louder and sounded good loud, but that was it. The A3CR only cost me $600 used and was worth every penny.
Now, my goal for my next amp, primarily for the benefit of the big OHM 5s in the bigger room, would be to get back up to or past the prior Carver's power levels but with an amp that can do the other things that matter at least as well as the 120w/ch A3CR. That in theory would put me in the best position I can be in at all volume levels, from lowest to highest, even with the OHM 5s. I'm thinking the difference with the OHM 100s in the room they are in will be more marginal at best, but we'll see. First, I have to convince myself to spend more money to improve the sound of a system that is already floating my boat just fine in most every regard these days.
Also remember that technical specs and optimizations alone still do not tell the whole story nor guarantee good sound. Different amps will still sound different or have their own distinctive sound. These are just the technical issues that you can control that if done will put in in the best position to reap maximum performance out of your system overall. Some amps may still sound bad and some good. Some of that is real and some is a result of individual preferences.
Efficiency in the sense that the power output doubles into 4 and then even into 2 ohms, not overall power delivered out versus consumed.
The Carver was a m4.0t, solid state, 360 watts/channel into 8 ohm but only marginally higher into 4 ohm (not even close to 720 w/ch), and not very high current delivery compared to most other "monster" amps with similar power specs into 8 ohm.
Mapman, in my opinion you've offered some really excellent, valuable comments.
The one thing I would add in the way of clarification is that your item 4 really equates to your item 3 + item 5. In other words, the reason that the ability to progressively double power as load impedance is halved is significant, is that it signifies that the amp has both high current capability (relative to its power rating) and high damping factor (which is the same as low output impedance).
"Efficiency" is probably not the best term to use for these capabilities.
Not sure about the output impedance of the Carver m4.0t.
I can't say for certain that bass levels were lower relative to other frequencies at lower volume than at higher volume for certain. It could be that the lower bass levels were just more noticeable as deficient at lower volumes. At high volumes, the rafters could be shaken by the 360 w/ch without any major tonal balance issues that I can recall. The differences in specs between Carver m4.0t and MF A3CR I recall that I could attribute this to were the power rating into 4 ohms, the damping factor, and/or the current levels available.
All, and I mean "all" of your responses to me and to one another have been a terrific little education. In addition to helping me with my question, (shoot-you helped me better understand my own question!)-now I can follow a lot more of the discussion within threads in this forum. Thank you.
In your search a useful strategy might be to go with a stereo amp that is bridgeable into mono. That may lower the cost initially but also provide the option to add a second similar amp later and double the power but only if needed. I may well end up going this way myself
If you're looking for a high power, compact amp to drive Ohms, I'd consider the Bel Canto (or similar ICE power designs). I've (briefly, but successfully) used their 150 WPC integrated with my Ohm 100s in a space similar in size to yours. I don't know, however, how your 1000s compare to my 100s in terms of sensitivity, or whether there would be any impedence matching issues with their power amp and your preamp(though I don't know why there would be).
Bob_reynolds: Do you have any idea what the output impedance is for the Carver amp? In the Sunfire amp Bob placed a 1 ohm resistor in series with the output and labeled those "Current" to provide a more tubish sound. I wonder if what you experienced with it versus the MF amp was the frequency response modification caused by the interaction between the amp's output impedance and the speaker's impedance.
Good point, Bob. I'm just about certain that the M4.0t was designed to emulate the sound of Carver's exotic Silver Seven tube amp. So it most likely did have a highish output impedance/low damping factor, with probable adverse effects on the bass, and increased sensitivity to variations in the speaker's impedance vs. frequency characteristics. And I don't think that on the M4.0t there was a choice of "voltage output" or "current output" as I believe was the case with the Sunfire's you referred to.
Mapman: It could be that the lower bass levels were just more noticeable as deficient at lower volumes. At high volumes, the rafters could be shaken by the 360 w/ch without any major tonal balance issues that I can recall. The differences in specs between Carver m4.0t and MF A3CR I recall that I could attribute this to were the power rating into 4 ohms, the damping factor, and/or the current levels available.
This strikes me as very likely. The bass weaknesses of the Carver would have been more noticeable at lower volume levels because they would have been accentuated by the Fletcher-Munson Effect, which GREATLY reduces the sensitivity of our hearing to deep bass frequencies (and also very high frequencies) relative to mid-range frequencies, when the overall volume level is low.
Martykl: I don't know ... whether there would be any impedence matching issues with their power amp and your preamp (though I don't know why there would be).
There wouldn't be. The preamp's 25 ohm output impedance is very low, and I suspect would be fully compatible with the input impedance of any power amp known to man (or woman). It's provisions for adjustable sensitivity on each input should also make it possible to avoid gain mismatches that might otherwise result in having to use the volume control near the bottom or top of its range.
AL, I think your assessment regarding the Carver m4.0t is right on target on all points. I do recall the damping factor to be quite low (which in addition to my ears led me to suspect it was not well matched for the OHM 5s) and yes it was a "Silver Seven" model.
Thanks again for all of your responses. It seems like I might be able to have success, and save some $, with either an MF AC3R (just missed one listed on CAM) or a Bel Canto es300. Any comments about differences between the two?
Haven't heard the Bel Canto so can't help you there. THe A3CR matches up nicely with OHM 100s in my system, plenty of natural sounding volume, huge soundstage, solid and defined low end, very good definition and detail, and not fatiguing. Some think the A3CR is a touch on the hot/forward side compared to some amps that are a bit softer on the top end perhaps, and there may be some truth to that.