WD Class D Amps?

[mikew27]

Well, I have to say that I'm quite pleased with the response to my first posting.Thanks for coming in Peter on this Peter. BTW my first proper pair of speakers were HB1s on the dedicated stands.
Ive been a passive member of this forum for a while & have found the advise & opinion on here most useful & entertaining.

I read somewhere(else) that the NuForce units put out a lot of RF does anyone have experience of this?
Also, I thought I read somewhere (or was it a dream?) that switch mode power supplies put a lot of noise into the mains. Does this means lots of power conditioning or AC regeneration to protect delicate signals upstream?

I just want something with enough current to drive 2.8 ohms between 50 & 400 hz without melting. Maybe if they matched gain & input sensitivity of some nice valve device I could use valves for mid & highs & Class D for the bass dept. (as this is what a lot of subwoofers use isn't it?)

BTW I asked B&W for impedance & phase plots for my 703s & they were unwilling to help.
All of this comes from an article in HFN&RR this month (the only thing worth reading so my subscription comes to an end soon) about power & current requirements to drive loudspeakers.

I case you all are wondering why i dont out the B&Ws for something more valve friendly they were a present from my wife so I don't want to discourage her from such acts of generousity in the (hopefully very near) future.

Michael

[charly]

The necessary parts from Hypex would appear to cost about £500.

[Ianm2]

slightly interesting, but my next foray may well be a pair of active speakers, with class D amps inside them and meant to be rather good, by someone who's ears I trust.

http://www.maudio.co.uk/products/en_...itor-main.html

they say they use pwm technology, I don't know if that's fully digital or not, but that combined with a smps could be superb.

efficient, cool and powerful

I am past lots of big boxes and wires everywhere, defo. going back to self contained powered speakers, with warrantee.

you'll be surprised how good they can be, having feasted off the caviar of the highest end, I can live with them very happily, its just a plug n play solution

[Greg.]

.....until you flex your butterfly wings once again......

Let us know how you get on, Ian.

Best wishes (as ever)

Greg

[alnewall]

Looks interesting Ian.
Be good to get another different angle on things.

[Black Stuart]

Using a hybrid h/amp which has a beautiful sound and in shootout beat 20 others including a Singlepower, I have no doubt that I would love to have a valve pre going into a class D power amp, better still two monos to use with an active x/over.

What I don't need is 100W jobbies - 15W per channel would do me fine. I'm glad that Leo likes the sound from his Hypex modules. It will also be good when he gets together with Richard and they can post their reactions.

[leo:)]

You can alter the signature of the Hypex modules just by changing a few components.
What would be very interesting is to totally remove the input buffer/gain op-amp and feed the amplifiers modulator direct with some nice valves.
I've tried a few different op-amps in mine and they all added a different signature, the LM4562 is about the most neutral, signal DC blocker caps are also bypassed.

[Black Stuart]

Leo,
in the Bada, the feed is from the 6SN7s into mosfets, there are no op-amps involved at all. Perhaps that's why it sounds so good.

[leo:)]

It could be Stuart its easily done with the UCD, its a case of simply removing the op-amps and fitting some valve stage and your done, Hypex use the op-amps because they are cheap and easy, more compact etc, the beauty is you can remove them altogether and add what you like, you can probably do it with some of the Tripath chips too but I think most of those have the input stage built into the same chip unlike the discrete UCD's.
You also have the input DC bias of the tripath chips to mess about with

You got the details for the amp you mentioned?

[leo:)]

Is this the amp you mean? http://wduk.worldomain.net/forum/showthread.php?t=3145

Can't you try something like this but instead of using the Bride of Zen as a pre use your 6SN7 stage http://www.pha.inecnet.cz/macura/follower_e.html
Its a simple circuit although you have to use the big coupling cap on the output

Maybe something like one of the Passlabs designs would be better, problem with the mosfet power follower is its only x1 gain