Benchmark AHB2 Tests and Evaluations: Part-2
Incorporation in Multichannel Multi-Amplifier System and Listening Sessions
Note: I am an end user audio enthusiast and I have no conflict of interest at all with any of the manufacturers, import companies, distributors and audio shops relevant to this post. This post is not intending to intensively share objective and/or subjective evaluations of the candidate amplifiers, but I would like to share about how I would test and try candidate amplifiers in this project.
Hello friends,
I assume all of you may agree with me that, in my current project, the extremely low distortion (almost zero distortion)
Benchmark AHB2 should directly and dedicatory drive the extremely low distortion YAMAHA Beryllium mid-range squawker driver (Be-SQ). Yes, yesterday and today, for the first time, I incorporated
AHB2 in my multichannel multi-amplifier system for intensive listening sessions.
As now I have one
AHB2 for my tests and trials, and I would like to drive woofers (WOs) by my ACCUPHASE E-460, this time I tentatively use YAMAHA A-S301(B) integrated amplifier to drive Be-tweeter (Be-TW) and super tweeter (ST) FOSTEX T925A, as I carefully considered in
my post #251.
Since A-S301(B) has only RCA unbalanced input and I do not like to use any of the XLR-to-RCA adaptors or cables, I applied the DAC8PRO's AES/EBU (CH1+CH2) digital out into my ONKYO DAC-1000(S) and the RCA unbalanced out of DAC-1000(S) into A-S301(B) to drive Be-SQ and ST. Only one low-cut 1.5 microF capacitor (AUDYN Cap 1.5 uF 630V) is in the SP line for ST for -6 dB/Oct at around 8,800 Hz.
Furthermore, just only for current trials with
AHB2, I dared to use OPPO SONICA DAC with its ASIO driver to give RCA unbalanced input to sub-woofer (SW) YAMAHA YST-SW1000. The main reason for this is that I do not like to have overlapped low signal of 15 - 55 Hz with the signal (45 - 600 Hz) for WO. I know well that, in this case, DAC8PRO and SONICA DAC is not in full sync and there would be possibility of drift into out of sync between the two DACs for the long music tracks. In my current trials, however, I rather frequently reset DAC-1000(S) to prevent the possible "out-of-sync", and it worked just fine.
Consequently, the total scheme of the tested system is like this;
View attachment 79469
You may look at the SP cabling boards;
View attachment 79470
On each board, you can see three blue protection capacitors (68, 10, 10 uF Jantzen Standard Cap 400V), one small black low-cut capacitor AUDYN-CAP 1.5 uF 630V, and three Jantzen Audio 22.00 Ohm 10W SuperRes resistors.
The software crossover EKIO's configurations remained unchanged;
View attachment 79471
and,
View attachment 79472
I did intensive listening sessions for two days with this setup, and I found and confirmed that the combination of
E-460 for WO and
AHB2 for Be-SQ is really amazingly wonderful giving extremely high quality sound all the way.
I also found that the use of an integrated amplifier YAMAHA A-S301(B) for Be-TW and ST was well fit for the sound of WO and Be-SQ, and it would be also convenient to control the Be-TW and ST volume level by the volume of A-S301(B) using the remote controller. This finding is now well encouraging me to further evaluate rather small power but high quality integrated amplifiers with XLR balanced input, like SOULNOTE A-0, in this project for Be-TW and ST.
Before finishing my two-day listening sessions, I carefully bypassed the three protection capacitors for Be-SQ, Be-TW and ST to check the possible audible effect by them;
View attachment 79473
Fortunately, I found little, almost no, inferior effect of these protection capacitors (Jantzen Audio Standard Caps). As I really would like to protect my treasure Be-SQ and Be-TW, I decided to use these protection capacitors at least all the way throughout my coming tests with several other amplifiers.
Let me just share with you a little bit of my subjective evaluation and impression. At the end of today's listening session with
AHB2 in above scheme, I seriously listened to this nice album which I always use as a reference of full orchestra sound with soprano solo and chorus,
Schubert "Rosamunde (Complete)", Kurt Mazur (conductor), Gewandhausorchester Leipzig, with Elly Ameling (sopraso) and Rundfunkechor Leipzig (Leipzig Radio Choras), Philips ASIN: B00000E2SS;
View attachment 79474
This album was recorded in December 1983 with really amazing recording quality. The first track
"Overture" is
pp to
fff full orchestra sound with very nice 3D perspectives, and with
E-460 for WO and
AHB2 for Be-SQ, together with SW and ST, the sound is really amazing; I feel as if I am sitting on the best seat in the Neues Gevanndhouse Leipzig. Among the very comfortable silky but vivid and gentle orchestra sound, now I can identify each individual violinist in the full orchestra. Really excellent sound quality by the audio system with
AHB2, and again amazing recording quality.
Elly Ameling sang only in track-5
"Romance" for just 3 min 47 sec and her posture and beloved voice were best seen and heard ever before, even though I have listened to this album more than hundred times. My tears really down.
The famous
ppp orchestra piece of track-7
"Ent'acte to Scene 3" is always a great challenge to audio system for orchestra string sound in good S/N without distortion; I cannot find suitable words how beautifully
ABH2 and my system played this track also...
Track-9
"Chorus of Shepherds" is another challenge to audio system for the balance of 4-part chorus and orchestra sound in the nice acoustic hall. In the middle of the track, each of the solo singer from soprano, alto, tenor and bass sing in the center-back of the stage, and we need excellent 3D perspectives and sound resolution for very much impressive listening experience which were perfectly achieved by the audio system with
AHB2.
I will continue testing
AHB2 for coming weeks. One of my audio enthu friends will bring his ROTEL RB-1852 MkII to my home in the middle of September for similar evaluation.
Hopefully, I would like to summarize my exploration for amplifiers in late October.