PWM Amps (a.k.a. Digital Amps) - Some info for you.

Sniper · 31-08-2005, 4:04 PM

I came across this:

http://www.psaudio.com/articles/sdat.asp

Very interesting read.

gavp · 07-09-2005, 11:18 AM

http://europe.rotel.com/products/specs/rmb1077.htm
http://www.hometheatersound.com/equi...a_intrepid.htm
http://www.hometheatersound.com/equi...esign_evo6.htm
http://www.psaudio.com/products/gcamc_overview.asp
http://stereophile.com/amplificationreviews/405yamaha/

From what I can gather toroidal amps sound better when being pushed whilst digital are able to sound more cohesive at lower levels, of course these are all very expensive, but is this the future?

I like the look of the ps audio one muself mmm 7000 watts....

pcavelle · 09-09-2005, 8:09 AM

I have one of these amps - a PS Audio GCC500. It's the stereo 'integrated' which is 500w/8 ohms and (supposedly) 1000w/4 ohms. I got it to replace a Krell pre/power and it's a decent amp.

A friend has just bought a GCC250, replacing a Primare something or other, and he's also delighted with it.

They're good amps, really well made, startlingly clear and punchy sound.

Any questions, please ask! I've been following this type of technology (especially IcePower) for a while now in a eerily geeky manner, so know almost too much about it!

Paul

Sniper · 09-09-2005, 10:47 AM

Interesting idea the GCC amp - like a poweramp with 'volume control'!

What exactly are you powering with those 500w ??

pcavelle · 09-09-2005, 11:17 AM

Martin Logan Ascent i's.

Wish I'd bought the lower model though, it's too powerful almost.

chedmaster · 09-09-2005, 12:05 PM

Quote:

Originally Posted by gavp

From what I can gather toroidal amps sound better when being pushed

Pretty sure toroidal is the type of circular power supply supposedly giving out less electromagnetic interference.

GaryG · 09-09-2005, 12:16 PM

Did you compare the CGA with the Bel Canto range? Also, how much of an improvement is it over the KAV250?

pcavelle · 09-09-2005, 12:27 PM

I didn't compare with Bel Canto, assuming it's me you're asking. The amp wasn't replacing a Krell KAV250, it replaced a different Krell stereo amp. It's a different presentation altogether, less warm.

Not sure what toroidal has to do with all of this anyway, it's only a type of transformer, nothing to do with an amplifier class.

Steve.EX · 09-09-2005, 12:28 PM

Quote:

Originally Posted by chedmaster

Pretty sure toroidal is the type of circular power supply supposedly giving out less electromagnetic interference.

Generally speaking i not a fan or rather perhaps weary of any switched mode supply, they tend to be electrically noisey, chucking (at times) large amounts of noise/current back onto the mains. In my field we occasionally have problems caused by said supplies.
Invariably what you gain in efficiency you may lose in other components being compromised by the mains quality. This is most certainly measurable, even with fairly unsophisticated monitoring kit. This sort of interference can upset performance at mains level, toroidals don't like it as well as sensitive low level stuff.

GaryG · 09-09-2005, 12:45 PM

pcavelle

(Paul, Meridian 596 years ago?) You've got me interested in this. I just read about the control amp, this would be ideal for me and allow me to use my DAC at full volume, however, after buying and selling a Bel Canto eVo4 as a replacement for my Krell MDA 300 monoblocs I'd like to be sure that it was an upgrade or a least a sideways step.

pcavelle · 09-09-2005, 1:04 PM

Hello Gary - yes to the 596. You still using it?

I bought the PS Audio amp to replace a Krell FPB600 & KRC HR as although they sounded great, they were too bloody hot, and massive. I also had a KAV250/a3 to power centre & rears, but altogether it was too many boxes, cables, space. Too much hassle.

I don't think it's a downshift necessarily, just a sideways shift, for about a tenth of the cost of the Krell stuff, some of which I still have in the attic. I was considering the Tripath based stuff (Bel Canto, ESL Labs etc) but wanted more watts for my ML speakers so I started looking at the IcePower based products like Jeff Rowland & Acoustic Reality - they both had products based on the 500ASP & 1000ASP boards. Then the PS Audio product turned up at the right price & with the right features.

It's a very controversial subject, Class D vs 'Old Skool', for some reason, with lots of debate on what sounds 'best'. All I can say as a former Krell owner (and a current one for that matter) is that I'm happy with the choice I've made & don't view it as a compromise at all. I'm certain the same applies to the Bel Canto's too, which I've heard are excellent.

Regards

Paul

Sniper · 09-09-2005, 4:15 PM

Quote:

Originally Posted by pcavelle

Martin Logan Ascent i's.

Wish I'd bought the lower model though, it's too powerful almost.

hehe... yeah just had a look at them speakers - nice! i'd say the 250w version would have done - but it's always nice to have some reserve power (100%

)

GaryG · 09-09-2005, 10:48 PM

Paul

Thanks for your comments. Do you know of any UK dealers stocking the Control amp? (other than Ulitmate Sonics)

Steve.EX · 09-09-2005, 11:33 PM

Quote:

Originally Posted by pcavelle

I have one of these amps - a PS Audio GCC500. It's the stereo 'integrated' which is 500w/8 ohms and (supposedly) 1000w/4 ohms. I got it to replace a Krell pre/power and it's a decent amp.

A friend has just bought a GCC250, replacing a Primare something or other, and he's also delighted with it.

They're good amps, really well made, startlingly clear and punchy sound.

Any questions, please ask! I've been following this type of technology (especially IcePower) for a while now in a eerily geeky manner, so know almost too much about it!

Paul

I am sure i would love to hear one.

pcavelle · 10-09-2005, 7:53 AM

No, only Ultimate Sonics have them in the UK & they're a shower of *****

**alexs2** · 11-09-2005, 6:38 PM

Quote:

Originally Posted by chedmaster

Pretty sure toroidal is the type of circular power supply supposedly giving out less electromagnetic interference.

No it isnt....it's as has been said...a transformer on which the primary and secondary windings are around a soft iron toriod(or doughnut shape).

It is as capable of giving out as much interference as the traditional shaped transformers,if poorly designed and screened,but has the major advantage of being relatively compact.

chedmaster · 11-09-2005, 6:41 PM

i was the first one to bring it up

when i said power supply i meant transformer. i was thinking computer style psu.

Steve.EX · 11-09-2005, 8:28 PM

Quote:

Originally Posted by alexs2

No it isnt....it's as has been said...a transformer on which the primary and secondary windings are around a soft iron toriod(or doughnut shape).

It is as capable of giving out as much interference as the traditional shaped transformers,if poorly designed and screened,but has the major advantage of being relatively compact.

I am of the opinion that "better"(?) toroidals offer several advantages (electrically speaking or, with regards to flux to be precise) over similarly sized frame transformers. But i'm kind of guessing a chap like you knows this.

Regards

Steven

**alexs2** · 12-09-2005, 6:06 AM

Quote:

Originally Posted by Steve.EX

I am of the opinion that "better"(?) toroidals offer several advantages (electrically speaking or, with regards to flux to be precise) over similarly sized frame transformers. But i'm kind of guessing a chap like you knows this.

Regards

Steven

Hopefully Steve!....the ones in my Krells are good....no noise,either mechanical or electrical,but their size and casing makes the amps the sort of thing you don't want to lift.

On the other side,I've come across some awful examples of each type....ones that have high levels of mechnical noise,and some you cant have within several feet of more sensitive bits of equipment(the PSU on a phono preamp springs to mind).