Hlly t-90 (cheap class D amp with actual power)

Ever since I first fell for the Sonic Impact t-amp, I've been intrigued about the prospects of a higher-powered Class D amp. As most people who follow these things know, Tripath went under a couple years ago, but they made higher-power chips. Sonic-Impact was promising one a couple years ago as was Mark Schifter's av-123, X-electronics. It's just that both turned out to be vaporware. PopPulse has also marketed an amplifier based on the Tripath 2022, a higher-powered chip, but I still haven't found a serious review.

Hlly electronics is a Chinese company that has offered a handful of Tripath-based amplifiers via E-bay and a North American distributor p-mac audio. They aren't the only Chinese company that has tried to capitalize on the success of the Sonic Impact and the Trends Audio, a more audiophile t-2024-based amp that was reviewed very positively. In many ways, they typify the joys and frustrations of doing business with Chinese audio companies.

My first experience with Hlly was with their T-2020 based amp, similar to the Trends but slightly more powerful (nothing significant). It sounded good initially, but it suddenly fried on me. They were glad to either refund me or replace, but wanted me to pay shipping to China. Unfortunately, the amp was 68 dollars and the shipping was 22. I give Hlly credit though, we worked something out and I wound up having them ship me a T-90, Hlly's own t-2022-based amp which boasted a promising 90 watts into 4 ohms. In other words, it promised to deliver tripath sound to speakers that aren't either horn-loaded, single driver, or meant to play from two feet away.

Unfortunately Hlly's original release of the t-90 was premature. It made a noise at idle and the muting circuit may or may not have been overly finicky. A few weeks earlier, the company had announced the implementation of new board for the t-90 and apparently dealt with the persistent hiss/noise issue.I was in one of those what the hell moods, so I took the chance. Hlly was very good about returning e-mails and was very straight in their dealings with me though there was a bit of a language barrier.

Before I review the t-90, I also want to mention that Hlly has landed their new amp in a peculiar market spot. The Virtue Audio One, 30 watts/channel (the Hlly is 60 into 8 ohms btw), but numerous rave reviews, is $250.00 which is more than the Hlly $180, delivered from China. I haven't heard the Virtue, but my guess is that a lot of people might prefer the “known quantity” aspect of the Virtue for what's not that big a price difference. Incidentally, the Virtue recently sold out all of its stock, either a clever marketing ploy or a sign of terrific marketing success in a tough market for audiophile toys.They rather ingeniously sold their products as a budget amp or a second audiophile-level amp for your computer.

When my Hlly-t90 arrived I was surprised by the size and weight of the package. The t-20 was well-built, but resembled a headphone amp in size. The t-90 was hefty and quite deep, maybe a little too deep to stick on a desktop next to your computer. Instead of including a switch mode power supply that plugged into the body, the t-90 has a toroidal transformer in the case, a surprisngly heavy transformer. Like the t-90, it has a solid metal case with a thick-milled aluminum front. The power switch is on the front and it includes a volume pot for possible use as an integrated amp.

I started the t-90 on my office system through a run of the mill laptop soundcard and a pair of Radio Shack Lx-5 speakers (late version). I loved the sound, but was surprised to find that the Hlly didn't sound a lot “louder” than the Sonic-Impact. My laptop soundcard doesn't have a lot of gain and I had noticed that the Sonic Impact had surprisingly good sensitivity. My initial impression was that the Hlly t-90 sounded very different. Where the SI T-amp is beguilingly light and airy, notably so, the Hlly is darker and more solid sounding. It may be that it restores the bottom octaves while the little t-amp had a filter below 100 hz. I was favorably impressed with the Hlly though, just wasn't sure that it's a good match for low end low output sound cards or medium-sized desks. Cards like the m-audios and even middling fare like the sound blaster audigies would probably do fine btw.

I took the Hlly home to try it in a higher-end system. For me, that's a relative term. I haven't bought big money equipment in years, but have had two great but very different amps in the past (both died). I had an early Richard Marsh-Bill Westerfield amp Mosfet AB huge power, incredibly fast, terrific authority (though not in the bottom bottom octave a mosfet thing), and unbelievable clarity. I also had a 300B with Western Electrics (NOS) push-pull from Canary Audio that one day stopped working (still have the tubes, though there are some brown spots on top of the glass) 18 watts but as harmonically beguiling as anything I've ever heard, wondrous midrange, pretty but slightly rounded bass, and clear-sweet highs. I've also built speakers for years and had design help with my Scanspeak monitors from Brian Smith.

I first tried the Hlly with a tubed preamp, the Scanspeaks (6.5 inch Kevlar 2 ways with a Revelator tweeters), and my older Sony ES CD player. Even with a pre-amp, the Hlly did better with the volume pot well past 12 O'clock, but it has plenty of subjective power. I noticed the following.

There's something about this amp and the human voice. Voices as different as Louis Armstrong, Rickie Lee Jones, Joni Mitchell, Johnny Hartman, and James Taylor sounded both distinct from one another and natural. For instance, I noticed that I understood lyrics and heard phrasing much more readily than I usually do. Where some, amps reproduce voices with tonal purity, the Hlly has that sonic quality that leads you to believe that you can see the shapes the singer makes with his or her mouth. Even more impressive, you can pick up the number of voices in a chorus and overdub effects to prevent older singers voices from sounding thin on the higher notes. With one singer I won't name, they were doubling her voice with just a touch of echo.

The second real glory of the amp is that it reproduces classical woodwinds with the same level of articulation. It's very good with timbres and you can identify things like bassoons, oboes, and clarinets quite easily while also picking up differences between the real thing and sythesized versions of these sounds dropped into the mix. This is often a sign of very good control of intermodulation distortion, something it shares with the lower-powered Tripath amps and my old 300 B-based amp.

Utterly unlike lower-powered amps though, the Hlly90 has real bass. Electric bass in particular has authority and bloom as does the bowed string bass. If there's one place I'd fault it here though, it's that the attack isn't as good with percussion as I've heard with the best AB and Class A transistor amps, though the Hlly is much less rubbery than low-powered tubes or the Tripath 2024.You feel like the amp really does control the woofer, I just wouldn't say that it has the slam of a really well-designed AB amp or maybe even my gainclone amps (3886-based powered speakers).

Conventional wisdom is that tubes are great on the back-end (overtone) end of the sonic envelope and that transistors are much better with the attack or the front-end. A lot of people note that the Tripaths and other digital amps split the difference. There's a bloom and airy quality to the sound of tubes at which even relatively inexpensive tubed amps excel. Transistor amps have traditionally done things like drums with authority, but you often have to pay serious money to get a transistor amp that breathes well, either that or you have to go to low-power Class A. The Hlly actually does both well, though not world class well (what do you expect for $180?)

One sign of a good amp is that it doesn't get confused with complex musical passages. There are points in say Prokofiev where the different sections of orchestra do very different things. A really good amp lets you hear the pluck of massed strings and the metal in unison brass sections. The Hlly not only lets you hear the sections of the orchestra as distinct and tonally different, but it lets you hear the different timbres and overtones within that section. It does equally well with rock music. It's quite good with detail, but intriguingly doesn't sound “detailed”. A lot of times, I was just really surprised to listen in and pick things up like which drum the drummer was hitting and with what or whether the pianist was using the sustain pedal. While it's not an overtly fast amp, I really did like it with rock and roll and with full orchestra at least partly because the Hlly tends to sound more open and fuller as you turn up the volume. The image is big and wide, but it's not super deep. For instance, the brass in an orchestra should sound several feet behind the soloist and it doesn't quite reproduce the depth and the height, though that could be a function of my source equipment.

I also brought the Hlly into the living room to test with my 8” 3 way floor standers (accuton mid and tweeter with cabasse woofer, about 88 db) . I didn't use a pre-amp here and matched it with a very inexpensive vhs-dvd player from Toshiba (89 dollars from Best Buy) with a variety of CD sources and a bunch of movies. This is simply a great amp for video. I also find that movies make for a very good test of audio equipment, at least in part because you become much less aware of “listening”. Men's speech didn't have hissing sibilants, dialogue was very understandable, and sound effects held both their position and level of loudness. Interestingly, my cheapo DVD player had plenty of output for the Hlly to sing without a pre-amp though I still recommend a pre-amp (micro-dynamics are better).

A lot of amp lovers like to brag that their amp is completely neutral sounding. That's not the case with the Hlly. It has a basic character of being dark, creamy, and a little bit more solid-sounding than airy (you actually want both the body and the air). Musicians and instruments are definitely there, it's not notes reverberating in air (my sense of the Sonic -Impact). It's vaguely euphonic, but unlike a lot of euphonic amps it's capable of surprising detail and pace. Contributing to the creaminess, it's arguably just a bit smoother or rounded sounding with rhythmic transients than would seem completely natural, but I'm talking about a hundred and eighty dollar amplifier. I've never had anything this inexpensive that sounded this good with real world speakers at performance-level volumes.

That said, I've had one issue with the amp and it's a bit troubling. It's got a very persnickety mute circuit. Hlly insists that it's an over-voltage issue. I probably don't have the cleanest 110 volt lines in my house, but nothing else here turns off spontaneously. On several occasions, I've had to do a bit of a dance getting it to play music again once it mutes. I did discover that it does better when I turn the Hlly volume way down when I turn it back on. I've also considered the possibility that the Tripath overvoltage circuit is actually protecting the amp in a good way. The tolerance is supposed to be 5 percent which in the US wold be 116 volts. I have measured the AC in my lines here and it wasn't 110 always, but it was never quite that high, but who knows. It does continue to raise the specter that Hlly maybe should test its products a bit more thoroughly before taking them to market, the feedback on the earlier verison of the t-90 had to hurt the model and brand some.

Assuming the over-voltage issue doesn't come back to haunt me, I have to give the Hlly t-90 a very strong recommendation at any price. For $180, it's an outstanding bargain though I'd still recommend checking out the Virtue One as well with its better pedigree and reasonably competitive price with the Hlly. In the meantime, Hlly has announced a full digital amp soon and I look forward to finding out more about it.

I've mentioned in the past that the best listening test of any equipment comes with time as in just what do you find yourself listening to with an amp and what do you start avoiding. With my 300B's small ensemble jazz and movies sounded incredible. With my Parasound 1200, I started listening to rock and roll a lot. With my Super T and Sonic T, I got into chamber music and acoustic small group stuff and avoided full orchestra and driving rock. With the Hlly t-90, it's orchestras, rock and roll, any kind of vocals, solo piano, chamber music, and movies. If I'm not leaving out much, there's a reason. It's simply a great real-world amp at a very affordable price. My other guess is that it has much more potential for tweaking than do the Virtue Audio designs.

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