As usual, I’m a little late to the party, but in a sense I was one of the last to get an invitation! Actually I was one of the last to order the BHK 250 Signature, mainly because I struggled with the financial impact of buying the amp, so it took me a little extra time to commit, but Paul and Scott convinced me it was the right thing to do. Boy, were they right! Thanks Paul and Scott! Further delaying me was the amp arriving a day after I went out of town for nine days. PS Audio really tried to get it delivered the day before I left, but Fed Ex would not cooperate and deliver on Saturday (am I not special to Fed Ex? (tongue planted firmly in cheek)).
Now for a little background. I’ve been an “audiophile” for a long time, starting with a Creek integrated, VPI HW-19, and Fried Beta speakers. A modest sytem that told me there were good things down this audiophile road. Over the years I have had for amps a PS Audio Elite integrated (bought new), a modifed Bedini amp (bought used), and for the past 13 years an Audio Research Classic 60 (bought used). For speakers I’ve been a Vandersteen fan for over twenty years, starting with 2Ci (bought new), then 3A Signatures (bought used), and now Model 5 (original model, bought used). While I have been reading audiophile magazines since the early 80’s, my expereince in upgrading has not mirrored the usually over the top effusing from the reviewers. That, in combination with my tendancy to be, uh, a little “frugal”, has kept me from practicing the Audiophile revolving door scenario of regular equipment swap outs. It has also driven me to pursue high value used components. Which brings me back to the Classic 60, it was a high value component and I have been pretty happy with it, though, in all honesty I never tried anything else, well at least anything that was supposed to be better. Now along comes this here amp…
I have been watching the development of the new amp for some time and I was very intrigued with the inital Hypex design in that it was very energy efficient (remember, I’m frugal). While the significant energy cost savings of the prototype Hypex amp was a good thing (the Classic 60 draws 370 watts at idle, 500 watts at rated output), my main concern was driven by my typical operating scenario of turning the amp on in the morning and leaving it on most or all of the day, at least in the cooler months when I tend to stay indoors more. (Side note, tube amps make great room heaters in colder months, a plus in my cold basement room). Aside from energy use, the long operation hours depleted the tube life. Audio Research doesn’t seem to believe in “stand by” where tube bias is reduced or shut off. Frequent turning off and on was not a good idea either, tubes tend to fail more often with start up current rather than steady state operation. While I have been a tube lover, I was fully aware of the dawbacks so I was still on board when Paul changed over to a more traditional solid state design, but my interest rose when decided to go with a tube front end. Front end tubes have a longer life and are more affordable (try pricing an octet of quality 6550’s), but get you some of that “tube magic”. The allure was just too strong to deny…
Now, onto some sound observations. When I returned home the massive box was just begging me to do something with it. I couldn’t unpack it then let it sit and idle with no load for a while or hook it up to another system, it went straight into the main system. After all, I’ve been waiting a while for this moment! On first listen I was quite surprised at how good it sounded right out of the box. There wasn’t any nasty harshness which seems to be a common trait of break-in. Just nice smooth sound with good bass and a nice wide soundstage. perhaps the run-in that PS Audio did ameliorated the worst part of break-in. I’ve been running it continuously since this past Tuesday, so just over 100 hours, and it has improved a small amount, but I’m not hearing any huge improvements. We shall see if further improvements come about. What I hear at this stage from the BHK 250 Signature, relative to my Classic 60, is (in no particular order), better bass, wider soundstage, better articulation, and greater ease. I’ll summarize each of these below.
Bass: My Vandersteen Model 5’s have a built in subwoofer, so they require a high pass filter between preamp and amp that starts rolling off around 140Hz and is 3 dB down at 100 Hz. As such, one might think the bass performance of the amp was not as critical as the rest of the frequency range. One might be wrong. I was surpised at the improvement in the bass, in terms of overall frequency performance I actually noticed the bass more than anything else. I wouldn’t say it is deeper, the subwoofer handles those double digit frequencies after all, but definitely cleaner and better defined.
Wider soundstage: Tube amps are known to offer a more three dimensional soundstage, whether that is accurate or an artifact, I don’t know and won’t go there! But the BHK 250 Signature provides a wider and more realistic soundstage compared to the Classic 60. Several of the recordings I have listened to so far have soundstages outside the confines of the speaker, something that was rare with the Classic 60. I will say my room is small, 13’ wide (at the speakers, but 16’ wide at the listening position) and 14’ deep, with a 7’ ceiling, so my ability to get a huge soundstage is, sadly, limited.
Better articulation: It’s still early in the evaluation, but my thought here is the BHK is just so much faster than the Classic 60 that everything is articulated much better. After listening to some music the first day I pulled out the Sheffield/XLO Test & Burn-in CD, my intent being to run the burn-in track on repeat overnight. Rather than jumping direct to that track I started at the begining to see if I noticed anything. For reference, I had played this disc not that long ago with the Classic 60 so I had some aural memory of it’s performance. I didn’t notice anything major with the first three tracks, but then I got to Track 4, the “clap” track. I nearly jumped out of my chair the claps were so sharp. To me the rise time of the signal is so much faster you get that sharp transient that goes right through you and elicits the involuntary jump! This shouldn’t be too surprising since tubes are a little slow and tend to add some fuzziness to the sound (which can be a good thing some times). I hear this same thing in regular music tracks, though to a somewhat lesser degree (probably due to recording technique). Things like bells and delicate cymbals just sound so clear, it’s wonderful.
Greater ease: I think this comes down to power. The Classic 60 is a 60 watt push-pull triode. Definitely not a power house but more power than you think and I thought enough. I have been told the Vandersteens need more power, and well, they’re right (duh). I’m not normally a high volume listener (trying to preserve what hearing I have left), but I did notice with the Classic 60 classical music at realistic volumes had congestion, distortion, and general unpleasantness that I do not hear in the concert hall. Given this I was hesitant to go to higher power tubes since I wasn’t sure I needed the power and it means either pentode operation (or a variant thereof) and/or more tubes (side note: the Audio Research Ref 110 was my “target” amp, yes I know it’s not a triode). With the BHK 250 Signature I get the power I need and some tubes so I got the best of both worlds. Most importantly, now the strain is mostly gone! There remains some, but almost certainly that is an artifact of my room. I really should do some work on that room…
Now for a few, uh, comments.
First the packaging. First off, when the box arrived it had one strap and four edge supports in place. The one strap was off center so I thought it had slid over. Turns out there are supposed to be two straps, one must have fallen off in transit. I was able to slide off the one strap without too much difficulty, didn’t want to cut it not knowing what lie beneath. Not sure this is an indication the straps should be tighter or Fed Ex likes to mess with their customers (unthinkable!). It is defintiely a sturdy box, but on opening I was a little surprised that the only thing keeping the top on was the strap. Everything inside was intact, the amp was inside a well sealed plastic bag with plenty of rigid foam cradling it, so no issues with the elements, but from the standpoint of security the straps seem a little lacking. I was able to get the amp out of the box with a grunt or two, but after removing I noticed some odd little “clips” on two sides of the inner box. Not sure what they are for, but seem to be some sort of lock. No instructions saying what to do with them either.
Operational issues. I only had one, my Classic 60 is single ended, so my first hook up of the BHK was with single ended cables. Got a nasty buzz, so must of had a ground loop. This didn’t occur with the Classic 60, so I tried a different set of interconnects to make sure nothing went wrong changing out the cables, alas, same problem. It was a constant level, not impacted by volume or if the DS (no preamp) was muted or not. Removing the cables from the BHK stopped the buzz. The good news is I have wanted to switch to balanced operation since I got the Vandersteen 5’s. They came with balanced crossovers, but I couldn’t use them with my Classic 60 (it’s single ended). I have been using a homemade crossover of high quality capacitors so switching to the Vandersteen crossovers probably introduced a small improvement on its own, but I don’t think it was anywhere near the change the BHK introduced. Thankfully, with balanced operation no buzz. I’m not sure if I would call the single ended ground loop a defect at this point, more experimenting is required.
In summation I am very pleased with the BHK 250 Signature, it is a wonderful upgrade to my system. To put it into perspective, I think it is a more significant upgrade than going from PWD Mk II to DS. That’s not a knock against PS Audio, but rather the PWD is an excellent product, whereas my Classic 60 was an excellent product 20 years ago, now long surpassed. I think it also confirms for me Pauls position that the amp is one of the most important pieces in the chain. Well done and highly recommended!
? When will they be available ?