Solid-State Power Amp Adventures

Back in the 1980s I toasted a number of amps (Linn LK2, pre-production LK75 and a Naim 160) trying to drive a pair of Linn Isobariks. I had a Perraux 1150 on loan that was up to the task, but I didn't think it sounded as good as the Linn or Naim. My second LK75 soldered on for some 10 years before giving up the ghost, after which I picked up a Bryston 3B. The Bryston never even broke a sweat driving the sub-4-ohm loads of the Isobariks.

At the time, I would have rated SQ as Naim > LK75 = Bryston > Perraux, but with so much time in between who knows how much of that was nostalgia.

I don't know anything about the Bryston preamp. (I went from the LK1 to a Rowland Consonance I picked up used for a song.)

 

Detailed third-party measurements of the Monoprice Monolith 7.
http://www.audioholics.com/amplifier-reviews/monoprice-monolith-7-channel-amplifier-review/3

 

The First Watts are a different company entirely and is a different use case for Nelson Pass. They have differing topologies, and do sound different, from model to model. Some of their designs have been released for public domain after their run, and people making clones have always bugged NP. There are new models that will come up all the time, but they're his hobby, so it can be hit and miss.

The Pass Labs series (from Pass Labs, the company) have differing sounds, and lineology. The X are class AB, the XA pure class A up to a point . The models were the original numbers, X100, XA100, etc. Changes in the topology brought forth the .5s, and the .8s.

The circuits have been refined and revised a long time, going back to at least the Alephs in the early 90s.

Pass Labs further had models that sounded alike, but had reserves of power. The XA 30.5 was class A for 30 watts then switched to class ab over that (up to 150 or so watts), the XA60.5 almost double that. The bigger the number the more ease you heard in the sound, so people matched the big ones with Maggies, etc. And the X are powerhouses also.

While the X series (I haven't had the .8s in the house yet) are good amps, they are still mid fi, I think. The XA100.5 and XA160.5 are very good, but you do need to match them well with cabling and speakers. They are warm, but detailed, like SET tubes. If you have inefficient speakers, the bass control in the XA60.5 and 100.5 wont be tight. The opposite in sound may be the Hegel, as a reference, and I am in the process of trying to verify that.
One last nuance, and I haven't heard this myself, but the XA60.5 and XA160.5 are supposedly more neutral than the XA100.5 and XA200.5.

I remember reading someone disparaging Pass Lab equipment, on the basis of price. I don't think they really mind or care. They continue to sell very well, though prices have started to go too stupidly high, lately. They're not D'Agostino, but they're not Parasound, either.

The one downside to them, is they sound best warm (as in been on for hours) and as they are class A, get hot. While that means seven or so hours running before they sound good, for convenience sake, you leave them on a lot. So your power bill can go up by half or more, if you are not careful. Plus all that ambient heat you have to get rid of.

You do have to match them to the speakers like headphones. You will see the XA used with neutral, revealing speakers, the X on more warm ones. It still needs to match, or isnt worth the price.

 

That's a very old pre and a slightly less old amp. It's a good price for the two together, but as with all things in that vintage they might need to be recapped.

 

Marv, you should know that Class-D is not digital. That's like saying that Class-A is analog, cuz it has the A.

Also, you don't listen to a signal amplification principle. One listens to a real world implementation of this principle which to some extent will exhibit the advantages and disadvantages of the said method. It is up to the engineer to emphasise the advantages of this method and lessen the cons via good design. And then one also needs to make sure that this design is faithfully realised in a real life product.

There are at least three Class-D topologies I know of. Most of the older designs really do strongly exhibit the disadvantages of this amplification principle. First of all - having the feedback loop before the output inductor will make the amp extremely load sensitive. Especially in the highs. Then there's the carrier signal - back in the day it used to be rather low frequency and thus bled into the audible range. Nowadays faster switches will get you higher frequencies which are less of a problem.

Only Sith deal in absolutes, Marv. I get why you wouldn't want to invest in Class-D again, because good Class-D is not cheap. I'd say that price wise it's on par with the better Class-AB products. The main advantage with good Class-D will be thermals, power consumption and thus form factor. And maybe performance with 2-ohm loads. I haven't heard a clear advantage in sound compared to Class-AB, but then again I haven't heard neither the nCores, nor NewclassD or whachacallem.

 

Since Class-D started rolling I will say that Ncore NC400 with it's accompanying switcher psu is worth a try. Only caveat regarding ''other NCores'' is that the commercial offerings are all over the place. I would trust the diy version with certainty, as this has all variables in place (psu and input stage).

It was sort of a ''f**k your religion'' moment for me when I first tried it. Especially after hearing some real shitty/mediocre sounding Class-D amps (Devialet 120 being noticeable offender for it's price tag) and some class-AB bricks, which admittedly none have been very high-end. I certainly have loosened my hate towards switchers and class-D tech.

In speaker amp terms the NC400 has similar character as Jotunheim to headphones, only more mature in terms of tonality and staging.
I wouldn't expect SET-like qualities from it, but it does many things really well. Grips the drivers with vice, clean powerful transients, very good clarity. Black background, on bar with my EC2A3. Tone is natural, unlike any AB amp I have tried.
It is let down by lacking in ultimate microdynamic shading (it lacks color, inner life) and staging vs SET, while at it macrodynamics are not as good either. At the same time it's not completely fair to ask for all the SET strengths and 400W in one unit. Even less so at ~ 1500 $ mark.

As far as my own exp goes I have not encountered anything that trumps it below 5k€ (I have simply not encountered anything more expensive in PA world), disregarding flea-watters.

 

I'm using a Class-D Lyngdorf Sdai-2175 and this thing is the most neutral amp i have ever heard. It just completely disappears and sounds even and composed regardless of volume, i don't hear any distortion, luckily it has a volume display otherwise i might damage my hearing or get in trouble with the neighbors. I hear the same tonality through this as i heard on the T3, source being Lynx>Yggdrasil. Very transparant and pure sounding amp.

 

True. I found a used Emotiva XPA-2 Gen II (not the new modular dudes) for about the same price. Much less to worry about.

 

It would be great to have a meet with speakers also, to give everyone a chance to hear various amp topologies (like good Class D). I've never loved an amp the way I love my D-Sonic(s). I now have one in the living room system also.

 

I have experience with class d. Built 3 different class d amps

honestly, compared to even cheap mosfet amps. very detailed, amazing bass and tight, but thin midragne, unrealistic tonality, clinical sound, lack meat on the bones.

I know even the top class d design like Ncore or Anaview, compared to good class A/AB seem to have those same characteristic.

Id suggest to pair class d with Warm speakers.

 

The modules are only a part of the design, input modules are also critical. I've A/B'ed my Class D amp against very beefy class A gear (tube 100% class A) and there is no "thin midrange" or "unrealistic tonality". Most of this is just bias from folks who expect to hear something thin/digital sounding. FWIW the amps I compared to were these: https://www.ravenaudio.com/Silhouette-MK2-Monoblocks_p_16.html

I've also tried Emotiva A/B stuff, Parasound, Adcom and many others.

 

Anyone heard the Rogue hybrid implementations (Sphinx, Pharaoh, Medusa or Hydra)?

I'm curious how much the tube input section and/or linear power supplies impact the Hypex-based Class D output sections...

 

Based on your criticisms of the Class D that you've heard, I have a feeling that you won't like the nCore stuff. I have a pair of the DIY NC400 mono blocks and would describe them as very competent sounding solid state, but lacking in staging, microdynamics, and ability to convey nuance. I've only used them with digital sources, but I find that sources all sound very same-y through the NC400s, to the point where it's hard to hear the unique character of a DAC or tell them apart.

That being said, my NC400s are currently being unused and I would happily lend them out if you actually want to hear them, @Marvey.

 

Interested in trying ICEPower class D? This might be fun to test since I installed their latest tech (ICEPower 300ASC's) a year ago. The amp's my daily driver because I *can* hear differences in DAC's, nice nuance and good low volume performance, rich sound.

Anyway, if you're on a class D kick I'd love send it to you for a bit, have a few spare amps to use in the meantime!

Possibly a good comparison or alternate to Ncore for you?

Detail:
http://bit.ly/2p46UEW
(I reallllly need to edit down those videos, I've since learned final cut)

Amp detail: (It's a PSAudio Trio C100)
http://bit.ly/2oWE2Dp

*It uses gain cells (gilbert cells) to control volume, signal does not go thru a pot or stepped relays.

 

I'm also happy to loan one of my D-Sonic amps for the meet - the M3-800S http://www.d-sonic.net/products/stereo-amplifiers/

Let me know.

 

I'm happy to bring my ST-10 along to a meet, I'm pretty curious to hear it compared to other class-D amps.

 

I dub this Mini Meet.. The trial of class d!