Melos SHA-1 arrival

The Melos arrived today. To early to post sonic impressions. However, I was struck by one thing. I've seen Melos/ZOTL comparisons here, but the amps are completely different beasts. The Melos is hybrid: 6DJ8/6922 gain stage with solid state output. The ZOTL is a pure tube amp: the driver tube is the 6SN7.

However, I've got another hybrid here: the X-Can V2. Runs on the same tubes as the Melos, also has solid state output...this seems to be a more valid comparison. Essentially, the Melos is a bigger, better, X-Can. As it is, I've got a quad of Amperexi that I can use to tube the Melos and X-Can identically, so it should be possible to compare the sonics without having to worry about coloration introduced by different tube types...hmmm....

Incidentally, the SHA-1 I have is very basic. On the back: three line level inputs and one output. Also a captive power cord. On the front, a power switch, LED, input selector, volume control, and two headphone jacks. Simple and to the point.

I agree completely that it is both acceptable and necessary to compare amps of any design, and fully intend to do so. However, it's usually impossible to compare tube amps without comparing the sounds of the tubes. What's the real sound of the amp, and what's the sound of the tube? The commonality between the X-Can and the Melos will let me tube them identically with high-quality tubes. So, with the tubes the same, the differences I hear will be those of amp design, rather than tube choice. It will be an interesting experiment.

The ZOTL has very little in common with either. It's a true tube amp, not a hybrid. Further, it uses Berning's Zero-Hysteresis technology, which so far is unique to Berning's products, so it's very different from other tube amps as well. One of the major problems that tube amps face is the high output impedance of tubes. Conceptually, both the Melos and the X-Can address this problem in the same way, by using solid state output. The execution may be radically different, but the approach is the same. Other tube amps address this by using an output transformer. Other amps are are OTL designs...

Traditional OTL amps lowered impedances by using a LOT of tubes in parallel, to get the output impedance low enough to drive a speaker with some power behind it. Headphones represent a good place for OTL design development, since even low impedance cans have higher impedances than most speakers, and power requirements of headphones are lower than most speakers. However, did you notice that most OTL amps still seem to work better with high impedence cans? Berning did something completely different, and invented a way to reduce tube output impedence that doesn't affect the tube sonics, as it works at radio frequencies. The ZOTL has an output impedence of 2 ohms...without solid state and without a traditional output transformer. It's a completely different technology than that used by anyone else, and one of the few true innovations to occur in tube technology in years.

You're right though, that in the end, all that matters is the sound.

Could I own the Melos for 24 hours before rolling the tubes?

No. I didn't make it that long. Switched to Amperex "A" frames. That clears up the high end just enough...cymbals now sound like metal instead of cardboard (stock Sovteks). That high-end was bothering me...new tubes fixed it. A very nice amp so far.

If my sig actually shows up, you'll see the weird setup I'm using to feed a single source to both amps. A switch would have been too easy...

Way too soon for a detailed comparison. One or two word impressions: Melos: power, authority ZOTL: transparency, grace

The Melos drives the HD-600 in a way that the ZOTL simply couldn't. It's not that ZOTL sounded bad, it's simply that the HD-600 and the 6SN7 tube seemed to never be completely comfortable together. If this was the only can I had, sorting this out would be easier. However, there's also the CD3K. Plug this into the Melos, and the life goes out of it. Lots of highs and lows, nothing in the middle. With the ZOTL, this can comes to life. The highs and lows are retained, but the midrange goes from lifeless to glorious...and the CD3K is almost indifferent to which 6SN7 I use...it shows the differences between them, but manages to sound good with all of them.

More to come...

Melos: the inside story

Click here to see image.

What I don't see is how Melos got a reputation for reliability issues. Interior construction of this unit appears solid. The big electrolytic capacitors are mostly Elna's, which are a high quality cap. Some are Philips, which I know less about, but still, there doesn't seem to be any skimping on part quality. Lots of space between the transformer and the circuit board, which is good (an outboard power supply would have been better). I've seen smaller toroids in power amps. 100-200 wpc power amps. That's one mother of a toroid for a preamp/headphone amp...no wonder the HD-600 sounds like it's serious when it's driven by that.

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EDITED BY JUDE 03-08-2002 02:58 EST: Changed the [img]-tagged photo to URL to prevent loading within the thread (mostly to prevent sideways scrolling).