Sunnyjim 6-21-2016 4:57 pm EDT
I have seen a used ARC 150.2 amp on ebay which is 150RMS. It looks clean but was, according to the seller was issued in 1993 which means it is 23 years old. It got mixed reviews, some loved it; some claim it is garbage. Seller wants $1400, but that is too much. I believe its market value may be $950 regardless of it ARC pedigree. It is either a tube or hybrid amp, and the seller claimed he upgraded two tubes.
Sunnyjim 6-25-2016 4:54 pm EDT
I am pretty much sold on either the ARC 100.2 or the ARC150.2. I like Odyssey amp products, but ARC always delivers high quality products. But this can change as I get closer to making a decision. According to ARCDB.WS the 150.2 was introduced in 2003 and discontinued in 2006. And it appears that it does not contain any tubes, and certainly not in the power stage which is class-T. Jim, I have no particular suggestions to offer in your price range, although over the years I’ve formed very favorable impressions of Odyssey products based on the comments I’ve seen. However I can’t help but express some skepticism about the ARC 100.2 and 150.2 (especially the class-T 150.2), regardless of the reviews and comments you have cited, and although I haven’t ever heard them. According to ARCDB.WS the 100.2 was discontinued in 2003 (having been introduced in 1998), and the 150.2 was discontinued in 2006 as I indicated. The class-T architecture that is employed in the 150.2 (and also the 300.2) is a proprietary variant of class-D. As we all know, class-D has come a long way in the last decade or so, and your Sphinx is a much more recent design utilizing a class-D power stage. It’s perhaps also worth noting that the company which developed class-T went bankrupt in 2007. And the only high end company other than ARC that I am aware of which produced class-T amplifiers, Bel Canto Design, has not utilized that technology in many years as far as I am aware (although I could be wrong about that). Also consider that ARC’s tradition of excellence, and presumably their area of greatest expertise, has primarily involved tube-based designs. And also consider the possibility of condition-related issues that might surface eventually if not sooner in a dozen or so year old amplifier. Apologies for the uncharacteristically negative post, but personally I would be surprised if either of those amps would turn out to be a meaningful upgrade relative to your Sphinx. Best regards, -- Al |
Hi Jim, Thanks for the comprehensive response, and the additional background. In addition to the suggestions the others have offered, if I were in your shoes, those shoes including the possibility of eventually replacing your GoldenEar Triton 7 speakers with a pair of Maggies, what I would consider doing is purchasing something like this Ayre V-5xe power amp, which is presently being offered here at $2900, apparently having cost $5950 originally. I would initially drive it with the preamp section of your Sphinx, and at a later time, if and when you feel the urge and finances allow, address the possibility of a preamp upgrade. The V-5xe is rated at 150W into 8 ohms, and would double that to 300W into the 4 ohm impedance of a Maggie. From Stereophile’s "Recommended Components 2012," in which this amp was rated "Class A," along with several other solid state amps costing up to $106K: The compact, beautifully built V-5xe delivers 150Wpc into 8 ohms and features single-ended and balanced inputs and speaker-wire terminals made by Cardas. Though it lacked some power in the bass and sacrificed “a little of that you-are-there-ness” produced by the best single-ended-triode amps, the V-5xe offered a highly resolving, dynamic, harmonically pleasing sound that was never fatiguing. “Open, airy, and sweet,” said ST. “What more do you want?” (Vol.29 No.5) My feeling is that pursuing a path such as that is likely to provide you with a more meaningful sonic upgrade at this time than investing a similar amount of money in at least most comparably powerful integrateds or preamp/power amp combos. While also being sufficiently powerful and of sufficient calibre sonically to be future-proof with respect to whatever speaker upgrade and/or preamp upgrade you may eventually choose to do. I have no affiliation with or knowledge of the seller. Good luck. Best regards, -- Al |
Hi Jim,
Before I submitted my previous post I had looked at a rear panel photo of the Sphinx, as well as at the manual, and subsequent to your response I did some further Googling on the question of driving a power amp from the Sphinx’s variable line-level outputs. I had also noted that the input impedance of the Ayre V-5xe is a very easy to drive 100K. And the Ayre’s sensitivity (the input voltage required to drive it to full power) can be calculated from its power rating and its specified 26 db gain to be approximately 1.7 volts, which seems reasonable.
The bottom line is that it seems to me to be very unlikely that what I proposed would not be a suitable approach. But when you speak to Mark at Rogue you might ask him the following:
1)Are we correct in assuming that the variable line-level outputs on your version of the Sphinx are functional, e.g., that the RCA jacks are not internally connected to nothing?
2)How much gain is there between the phono inputs and those outputs?
3)How much gain is there between the line-level inputs and those outputs?
4)Would running the Sphinx with nothing connected to its speaker-level outputs have any adverse sonic effects on the variable line-level outputs?
5)Would running the Sphinx with nothing connected to its speaker-level outputs pose any threat of damage?
It seems slightly conceivable to me, although unlikely, that question 2 could turn out to be an issue, in terms of having enough gain to be able to drive the external amp to full power when using a phono source. I would be very surprised, though, and it would not speak well of the design, if the answers to any of the other questions conflicted with my suggestion.
Best regards,
-- Al
|
Hi Jim, Thanks for the nice words. Regarding: I shot off an e-mail today to specifically to Mark O’Brien about whether any of the inputs numbered 1, 2, 3, can be used as true pre-amp out. I’ve been assuming that the rear panel of your Sphinx looks like the following, which is how it is described in the manual and is how it appears in numerous other rear panel photos I’ve seen: http://rogueaudio.com/Images/sphinxrearlrg.jpgIt would be the "Output Var" jacks that would be used to connect to an external power amp, assuming those are present on your version of the Sphinx. I would definitely not expect inputs 1, 2, or 3 to be suitable for that purpose. Regarding the weight of the Ayre V-5xe, while the ad I linked to indicates 75 pounds, apparently for its shipping weight, both the manual and the description at the Ayre website indicate that the amp weighs 55 pounds. I would think that the magic of good sound would lie first in the pre-amp, not necessarily the power amp, unless it grossly under powered. Though, from my limited understanding of power amps having owned a few, power high current, low noise and especially low THD and IMD are the requirements to make a qualitative jump in sound quality. First, I would ignore THD and IMD specs in just about all cases, as they have little if any correlation with sound quality. Although I would be cautious about a power amp having THD numbers that are extremely "good," as that may be indicative of heavy-handed application of feedback in the design. Which in turn can result in excessive Transient Intermodulation Distortion (TIM), which is not normally specified, as well as excessive amounts of the specific components of harmonic distortion that are most objectionable (even though the TOTAL harmonic distortion may be very small). Second, I am not a believer in generalities about the relative importance of preamps and power amps. It depends on the specific case, IMO. And in the case of a modestly priced integrated amp employing a tube-based line stage and a class D solid state power stage, my instinct is that it is more likely than not to be the power stage that is the sonic weak link. Regarding the ARC 100.2, my biggest concern would have been the possibility that due to its age it would no longer sound as good as it once did, and/or that it would develop age-related problems in the not too distant future. Finally, I have no particular knowlege of AVA products, but you may want to seek out posts on one of their products that have been made here by member "Schubert," who owns and has raved about one of them (I don’t recall which). I have particular respect for his sonic judgments. To add a bit of context to that, btw, I'll mention that as in my case most of his listening is to classical music. Good luck. Best regards, -- Al |
FWIW I would hesitate to replace a newer amp based on switching technology (Class D) with any older ones.
I agree completely. To be sure it's clear to everyone, though, the ARC 100.2 (which was introduced in 1998) is not a class D or other switching design. As I mentioned earlier, though, the ARC 150.2 that was also being considered, which was introduced in 2003 and discontinued in 2006, is a "class T" design, that being a proprietary variant of class D. Best regards, -- Al |
He indicated that the variable input ( pre-out) was used to connect a second amp or subwoofer.
That would be "variable output," of course, not "variable input." Also, I found that the AVA amp which I mentioned has been highly praised by member Schubert is the Synergy 450, which I see lists at $1999. He posted the following comments in this thread which you had originated about 3 years ago: Schubert 4-10-2013:
I bought myself a new AVA Synergy 450 for XMAS, it much outclassed the
Odyssey amp I was using, very dynamic and enables me to hear every line
in the Symphonic music I primarily listen to. My biggest complaint is
cheap plastic speaker terminals placed in tight space pretty much limits
you to banana plugs....
Schubert 12-31-2014:
I have had a Synergy 450 for 2 years, first time in 40 years I haven't been looking for a different amp. Sounds like a high-quality 100 watt tube amp using NOS output tubes better than any currently available. Easily betters the Hafler, Odyssey, Belles, McCormack and Quad amps I used before.
Best regards, --Al |
Does the NuPrime ST-10 digital amp (150 RMS) qualify as a Class D amp, or a variant of Class D?? It is apparently a proprietary variant of class D. The mention in its description of a 600 kHz switching frequency, 85% output stage efficiency, and its power-to-weight ratio (150 watts per channel, weight of about 13 pounds) all point to class D or something similar. And this, from the TAS review that is linked to at the NuPrime site: Although the ST-10 is a “digital” power amplifier, it is not a standard Class D switching amplifier. According to NuPrime’s owner’s manual, “Instead of the conventional sawtooth configuration, NuPrime’s patented circuit design uses an analog-modulating signal that adds neither noise nor jitter. Rather than reverting to off-the-shelf solutions, NuPrime’s in-house advances have further unlocked the switching amp’s potential without the difficulties pure digital-switching amplifiers simply cannot avoid.” The cliché that should follow would be, of course, “Not your father’s Class D amplifier.”
If you look at the first figure in this Wikipedia writeup on class D amplifiers, I would speculate based on this comment that the "triangular wave generator" shown in the figure is probably replaced in the NuPrime design by some sort of signal having less abrupt transitions between its positive-going and negative-going segments. Otherwise I’d imagine that at a conceptual level the design is generally similar to what is shown in the figure. BTW, despite the reviewer’s reference to the ST-10 as a digital power amplifier, and despite popular misconception, class D amplifiers and similar variants are not digital amplifiers. As stated in the Wikipedia writeup: The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time. The smallest amount of noise, timing uncertainty, voltage ripple or any other non-ideality immediately results in an irreversible change of the output signal. The same errors in a digital system will only lead to incorrect results when they become so large that a signal representing a digit is distorted beyond recognition. Up to that point, non-idealities have no impact on the transmitted signal. Generally, digital signals are quantized in both amplitude and wavelength, while analog signals are quantized in one (e.g. PWM) or (usually) neither quantity. Basically, class D is an analog process. Regards, -- Al |
Hi Jim, As you may be aware op amps ("operational amplifiers") are solid state integrated circuit devices that are often looked upon with disdain by audiophiles. In part because op amp-based implementations tend to be less costly than other approaches. That disdain is justified in many cases, but certainly not always IMO. As is usual in audio, it comes down to the quality of the particular device and the particular design. As well as to the resolving power of the rest of the system. I was also informed by the Rogue tech that the sound may not be quite as good through the op-amp device, but he also claimed the op-amp is a very good device. In the absence of a basis upon which to "calibrate" this statement, my guess is that it would still be a reasonable plan to initially upgrade to a separate power amp, and consider a preamp upgrade at a later time. But obviously that’s just my guess, FWIW. The 10K minimum load recommendation, btw, is very reasonable, and most amps will meet that requirement. Best regards, -- Al |
P.S: Regarding "if I connect a separate power amp to line 3 which is a variable output ...," this still strikes me as incorrect, as well as being in conflict with statements in the manual. As can be seen in the rear panel photo I linked to earlier, line 3 is clearly marked as being an input, not an output. The variable line-level output corresponds to the pair of jacks labelled "Output - Var." Or at least it **should** correspond to those jacks, unless someone made a completely dumb mistake in the design, which I doubt, or if your unit is somehow different than what is shown in the photo and described in the manual. Best regards, -- Al |
