Parasound A23 - Amazing comments from a self-proclaimed expert (part 2 - see part 1 on my earlier thread)

Mr Tripp

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Aug 1, 2019
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To provide contrast and perspective, below are excerpts from a review of the A23 written by another audiophile as presented in a well-known industry publication. I believe you will find the differences between these two reviews in regards to content, opinion and professionalism quite astounding. As this second review is lengthy, only selected excerpts from the printed article, along with samples of the lab data and testing results, are included.

“At Parasound, John Curl insists his designs use the finest parts possible, avoid the use of capacitors and inductors in the circuit path, while continuing to use balanced circuits despite the additional costs. Schram once said of Curl - "He wouldn’t last a week in a mass-market factory. The bean counters probably would reject every part he picked because it cost too much. At the same time, he knows how to make a very, very good product at what we consider to be a reasonable price. The challenge is to make very good amplifiers in a way that is cost-effective.”

“While the front panel of the Parasound A23 is almost devoid of controls, the rear panel offers far more controls and features than you’d expect including balanced and unbalanced inputs and a loop-through enabling the user to route an input signal to an additional amplifier. There are also two volume controls—one for each channel—so not only can you adjust volume, you can also adjust channel balance. These controls have a smooth action, rather than a ‘click-stop’ action, so if you need perfectly precise level adjustments, you’ll likely have to use test equipment. At the left of the rear panel is a suite of options for turning the A23 on and off. You can do this manually, or have the Parasound auto-sense the presence of an audio signal and switch on automatically in which case it will switch off automatically once it no longer detects an audio signal. In our opinion, these represent helpful and well-thought out design initiatives.”

“The speaker terminals are certainly serviceable, and they’re gold-plated multiway types, so they’re not exactly ‘budget’ terminals. Internally, the A23 contains a massive custom-made 1kVA encapsulated toroidal power transformer with independent secondary windings for each channel and two big aluminum heat sinks which eliminate the need for noisy fan-cooling. The amplifier is further protected from misadventure thanks to the use of d.c. servos, relays and fuses, along with thermal protection.”


In Use and Listening Sessions

“Operationally, everything worked perfectly, though the rotary controls for bass, treble and balance felt a little stiff. The input source encoder, on the other hand, rotates smoothly and with a sound that is automatically and momentarily muted during switching. When listening, I quickly came to appreciate the A23. The most obvious contribution was its dynamism - the A23 effortlessly delivered thunderous crescendos. During listening sessions the A23 was always audibly invisible - the music sounding better than I ever remember it. For me, there is no greater proof of superb amplification. I used 3 different speaker set-ups: a floorstanding pair, the same pair with a subwoofer, and a pair of bookshelves both with and without a sub. The A23 performed brilliantly across all 4 combinations, but excelled with the subwoofer in the mix, particularly with the floorstanders as I could set the X-over at a low frequency that perfectly integrated the subwoofer resulting in full range from the floorstanders and only sub-bass from the subwoofer. “

Laboratory Test Results


"NOTE - These test results cannot be compared to Parasound’s own specs because Parasound specs each of its amp separately while the lab tested the A23 together with its companion P5 preamp. Hence, the distortion results are the sum of the A23's THD and that of the P5. Separately, each component would have lower levels of distortion than shown here. Testing was done in this manner because, in practice, this is the way most people use their gear.”

“Frequency response (FR) - You can see that the overall bandwidth of the A23 / P5 combo is very wide, being just 3dB down at 4Hz and 116kHz. If the dB limits are constrained overall response extends from 9Hz to 57kHz ±0.5dB ... from 20Hz to 20kHz the response is even flatter. The A23’s FR when driving a load typical of a two-way system revealed the amp’s performance to be identical to that into an 8? load - meaning the A23 will sound the same no matter what speakers it is driving. Very few amplifiers, regardless of price, are capable of this high standard of performance. However, in the interest of full disclosure, the linearity of the FR does come with one proviso - the tone controls circuit needs to be defeated to achieve this response. With the controls switched out, the measured FR is very flat whereas with the control circuit active some minimal variances were detected. Output volume will increase when the controls are switched out so, if you are using tone controls, err on the side of caution since the bass control yields more boost and cut than most tone control circuits—around 17dB compared to the typical 10–12dB. The treble circuit also offers a high level of boost, but using modest levels of boost, will eliminate any potential issues. Channel separation was quite good, particularly at high frequencies where it was measured at 49dB. This result is more than required for the A23 / P5 combo to deliver audibly excellent imaging and channel separation. Level matching between channels was only slightly off, but the 0.5dB mismatch is tiny and completely inaudible. Inter-channel phase errors were likewise extremely low, particularly at low frequencies. Distortion levels were also very low across the board, particularly at lower output levels where the A23 would typically operate in most "real life" applications. The noise floor is significantly more than 120dB down over most of the audio band, increasing only at very lowest frequencies, where you can see it’s at around –100dB. Overall THD+N was an extremely good 0.004%. Distortion levels increased with increasing output but even at full rated output all harmonic distortion components were more than 90dB down and most were more than 100dB down (0.001%). Intermodulation distortion and noise were both also very low. Measured S/N ratio at 78dB (unweighted) and 85dB (weighted), but when referenced to rated output improved dramatically to 97dB and 102dB, respectively - outstanding results on both counts. The A23’s damping factor was measured at 800 - again, absolutely outstanding performance. This means the A23 will control even the most undisciplined loudspeaker cones thanks to a damping factor that is ten times greater than will ever be actually required. The same could also be said of power output - the A23 effortlessly delivered far more power than most of us will ever require no matter how inefficient the loudspeakers. As the A23 will deliver even higher output levels when only a single channel is driven mean that it’s capable of even higher levels of ‘dynamic’ power, so you’ll get even more power on musical transients. Importantly, the Parasound delivered these very high power output levels at the frequency extremes (20Hz and 20kHz). While the A23 revealed a limitation when driving 2? loads at 20Hz, the amp’s protection circuitry cut in to ‘limit’ power output to 200-watts, at which point the amplifier would otherwise have been delivering continuous current of 20 amps. Square wave performance was outstanding, as you’d expect given the A23's performance in the FR and damping factor tests. Nonetheless, the 100Hz oscillogram exhibited a slight bit of tilt due to the overall response being 2dB down at 4Hz. The 1kHz square wave verges on perfection, while the 10kHz square wave shows only the slightest rounding - expected given the measured 116kHz bandwidth. Performance into a capacitive load was likewise outstanding. As a result, and in conjunction with its proven performance into 2? loads, the A23 will be completely stable into even the most difficult and demanding loudspeaker loads.”


Conclusion

“Overall, the performance of the Parasound P5 / A23 combo was simply outstanding with particular kudos due the A23. Very few amplifiers, regardless of price, are capable of the high standard of performance noted during our testing. Parasound is a rare company - one with a world-wide reputation for state-of-the-art sound quality and engineering that also delivers superb value. Looking at the A23, it’s easy to see why - buy it and you’ll get a lot of power and incredible performance for what, quite frankly, is a ridiculously low price. But given the credentials of its designer, I would not have expected anything less!”
 

Macattack

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Aug 21, 2014
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Yin and Yang. For every action there is an equal and opposite reaction.

Good example of why I let my ears (and wallet) tell me what sounds good to me.
 

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