UCD180 questions

[mr_push_pull]

That was just a (bad?) joke.

All I'm saying is that for 180 euros/pair it's a hell of a deal.

[Yves Smolders]

personally? For the money i'm willing to spend, yes!

I never heard it head to head with other amps (except for my own, which aren't expensive, a '99 midrange japanese reciever...)

The things I like most are the effortless dynamics, the soundstage and most of all, higher frequency sounds are just that much better and calmer - any other amp was harsh on my ears before I heard this one.

Krells would better be an improvement on the UcD's if you look at the cost of these!

When totally finished, I'll take my amp to the high-end shop to audition new B&W's, where i'll put it up against some high priced gear, and see what it gives.

I'm not going to say that this amp is the "mother of all amps" but for the price I paid, I can't imagine anything better - except newer and better class-D designs.

Maybe it's very subjective, but it's... my kind of sound.

I think these amps, if modded with new caps and such (weakest link I guess), can give any amp a run for their money, except for extreme low-ohm speaker situations, then the amp limit comes in to play. really expensive amps can pump a lot more amperes.

Then again, UcD has 2 transistors to amp the signal, some of these big bad boys have 8 or more.

[ewildgoose]

OK, sorry I misunderstood.

I haven't owned all that much in the way of seriously high end gear, but I think my UCD400's with decent caps and powersupply are probably weighing in with £2,000 to £4,000 gear.

That said, it's a qualified comment because I think in terms of stereo imaging and bass control the UCD is probably one of the best things I have *ever* heard, and certainly would compete with £10,000+ amplifiers that I have heard. It grabs speakers and takes hold of them in an Iron grip and produces incredible imaging and solid bottom end (true of nearly all Class D amps though)

The only area which I think it is not in the *unlimited* price bracket is the very top end treble. Howeve, that said I just built a new amp (pictures on the way), again with UCD400, and this time using normal aerovox caps (not the T things). I put 40,000uF per module (20,000 per rail) and each module has a seperate powersupply. This seems to pip my previous amps in quality terms and in particular the treble is even sweeter.

My test is whether you can turn the amp up to shocking levels and then whether it *sounds* loud, ie whether distortion is setting in. Really low distortion speakers and amps will let you ruin your hearing very easily because they don't *sound* as loud as a distorting boom box.

So actually with this high end powersupply (which probably cost as much as the modules), these amps really take a step up in quality.

In case a potential buyer is reading and assuming I am criticising - far from it. This is by far the best amp I have ever owned, and it competes with the best I have *ever heard* regardless of price. My comment is only that it doesn't perhaps compete with *unlimited* priced amps at the very top end of the treble and perhaps a tube or SET amp would be *slightly* better for the top end?

I took my older Zappulse and UCD400 amps to the local hifi meet where they were up against a serious Class A Pass Labs design and I think they more than held their own - according to the group! The new UCD amp will be going along to the next meet and hopefully be up against even stiffer competition.

I'm looking forward to seeing more commercial amps based on the UCD. I think it's a very high end amp, even more so when you consider the low price.

[maxlorenz]

Well said, ewildgoose

I also think that UCD's are forgiving with not-so-good sources but obviously sound excellent with better ones, wich will appeal to a larger audience
I think it has to be with some kind of HF noise rejection. At first you think that it has lower HF extension and later you realize that you only hear natural sounding highs

OK, some of you will say that it's only "geting used" to the sound but I think that the "relaxing factor" that is perceived with UCD's is maybe due to our brain's recognition of a "naturally reproduced" sound. Maybe I'll move to the "perception and reality forum"

Enjoy.

[Yves Smolders]

I think it has to be with some kind of HF noise rejection. At first you think that it has lower HF extension and later you realize that you only hear natural sounding highs

Yes, that's the first thing I noticed as well.

Firstly... "Hey, high sounds different... like less?"

A bit further on the listening test: "Hey, highs are so clear now!"

The secret sauce of the UcD is the harmonic distortion that is the same across all the bandwidth of the amp. That's what sets it apart from typicall class AB sound - which you don't "know" until you heard UcD.

Getting used to? Listen a few 100 hours on your amp and then go back to your former amp (I did, as I tested the UcD's on my receivers' PS and then moved it to another case) - it was really shocking, the highs were blown, staging gone, and the dynamics flat. It's worse going back than going forward.

[classd4sure]

Hi,

Really a 100 hours? I'd think it wouldn't take more than a few dozen to disgust you with the tinny and fake sound most other amps have.

I understand the UcD is not unique in it's harmonic ability/frequency response, but they are rare and the others who do manage it haven't done it cheaply.

Regards,
Chris

[DSP_Geek]

Originally posted by maxlorenz
Well said, ewildgoose

I think it has to be with some kind of HF noise rejection. At first you think that it has lower HF extension and later you realize that you only hear natural sounding highs

Originally posted by Yves Smolders


Yes, that's the first thing I noticed as well.

Firstly... "Hey, high sounds different... like less?"

A bit further on the listening test: "Hey, highs are so clear now!"

I suspect reduced RF susceptibility might have something to do with it.

Wendy Carlos has a studio in New York City, where RF noise levels are quite high, and in desperation installed a Faraday cage around the control room. Lo and behold, the noise floor on every piece of gear decreased, in some cases dramatically.

What does this have to do with amplifiers? In downtown Montreal, another RF rich zone, I found shielded speaker cables seemed to provide a blacker background for music. It's as you mentioned - there appeared to be a bit less highs, but listening further showed what was missing was a sense of "fuzz" between the notes.

Why would class-D amplifiers be less prone to this than standard amplifiers? There has been some speculation that RF noise on the speaker lines could get injected into the feedback path and get rectified at the junction of the differential pair. Why not UcDs? Take a look at the output stage: the very last component is a largish capacitor, which would tend to soak up stray RF coming in off the speaker leads before it comes close to the feedback path.

I suspect, just on a hunch, that class-Ds might also be relatively insensitive to speaker cable variations, but that's a topic for another day.


Cheers,
Francois.

[mr_push_pull]

Originally posted by Yves Smolders
It's worse going back than going forward.

Yeah, back at ya. This applies to all audio gear, when you're in doubt about the difference just switch back to crap and you'll see.
Btw, I have listened to the UCD's (although NE not AD version) with some tweaks (I suspect upgraded caps) and the feeling about the high was the same. Btw, speakers were Infinity RSII (reference series from the eighties, open baffle tweeter and mid, ribbon tweeter, closed - I think - bass section, 2 x 8 inches poly drivers, some say that among the first PP in the world). Anyway, that thing still sells for around $2000, original price I think was around $10k, maybe more? Ah, and source was M-Audio soundcard. At any rate, Dire Straits made my skin crawl on this setup.

[mr_push_pull]

Originally posted by ewildgoose
But they are also fairly high bandwidth amps, so you will get out what you put in up to I think it was around 45Khz?

Is the filtering done by the input opamp? Does Bruno give any details about this?

[ojg]

Originally posted by ojg


You're right. There's a review of it with full measurements in the August edition of Stereophile.

And now the review is up on their webpages:
http://www.stereophile.com/amplifica...cia/index.html

Interestingly Mr. Atkinson took some new measurements after CI Audio fixed a "bug" in the original amp that limited the current output. The original sample only achieved 55W into 4ohm!. Even more interesting that the distortion at 1W/8ohm also improved by 20dB in the new version.

Sooo.... Maybe Jan Peter or Bruno have some comment on this? If I buy a UcD from Hypex today, which version do I get? And what versions have already been sold?