Mains power puzzle

Yes, voltage regulation as well as saturation protection. This was also how Bob got to use such a small transformer in those amplifiers... You can't plug that amp into the outlet without the triac without blowing a fuse. I think it was a pretty cool way to do that atually. Except for added light dimmer style electrial noise that might be heard in other equipment around the house. Not sure if that method would fly in Europe these days with the lower PF ?

Speaking of FTC requirements, nobody seems to do that anymore. Even back in the 1980s, the M400 did not IIRC meet the full power at

With the teired power supply rails (both channels from the one supply), those amplifiers have more crossover distortion levels than just zero-crossing.

The M400 was fine as an amplifier practically speaking. I know how Bob Carver works having worked for him around 1973.

fredag den 6. december 2019 kl. 20.38.07 UTC+1 skrev snipped-for-privacy@gmail.com:

voltage across the outputs at the peaks of current. Now turn it down to sa y ten watts. That is a little over one amp going into eight ohms.

bly might dissipate 60 watts - making a little over a watt output.

exactly but it shares the load a different way than other amps. There is t he low, intermediate and high supply. The low supply is about +/- 40. the n ext around 60 and the high at about 80.

e headroom is what heats them up. In fact that is why testing on amps like by hersch-Houck was preceded by a warmup of an hour at one third power. It is about as hot as it can get then and some amps went into thermal shutdown because they were just running a continuous sine wave through it. Way diff erent than music, and specifically designed to beat on the amp.

e linear, tracking the audio and keeping the supply voltage ahead of it.

ctuations to screw that all up. The thing is right on the edge in the first place, but seems to hold up.

C like that and make a signal by changing the phase at which it fires asymm etrically. Since TRIACs are not the fastest thing on the planet it would be limited to servo control or possibly subwoofer amps. But we are talking on e output device fed by a switcher with some tuning to make it put out more of a sine wave at some frequency the TRIAC can handle.

bout which I had misconceptions. Forced to study in detail has revealed qui te a bit. For example, before I had the print I was taking some quick ohm/d iode tests for shorts right away and saw how it reads and thought WTF ? It was a Crown grounded bridge. Well that splains it...

Even if it was patented that surely has run out by now. I think most engine ers and manufacturers don't like the component count, because there is no c hip that does this.

Carvers dimmer might have been new, but the rest is just class-G (or H depe nding on who you ask)

fredag den 6. december 2019 kl. 20.38.07 UTC+1 skrev snipped-for-privacy@gmail.com:

voltage across the outputs at the peaks of current. Now turn it down to sa y ten watts. That is a little over one amp going into eight ohms.

bly might dissipate 60 watts - making a little over a watt output.

exactly but it shares the load a different way than other amps. There is t he low, intermediate and high supply. The low supply is about +/- 40. the n ext around 60 and the high at about 80.

e headroom is what heats them up. In fact that is why testing on amps like by hersch-Houck was preceded by a warmup of an hour at one third power. It is about as hot as it can get then and some amps went into thermal shutdown because they were just running a continuous sine wave through it. Way diff erent than music, and specifically designed to beat on the amp.

e linear, tracking the audio and keeping the supply voltage ahead of it.

ctuations to screw that all up. The thing is right on the edge in the first place, but seems to hold up.

C like that and make a signal by changing the phase at which it fires asymm etrically. Since TRIACs are not the fastest thing on the planet it would be limited to servo control or possibly subwoofer amps. But we are talking on e output device fed by a switcher with some tuning to make it put out more of a sine wave at some frequency the TRIAC can handle.

bout which I had misconceptions. Forced to study in detail has revealed qui te a bit. For example, before I had the print I was taking some quick ohm/d iode tests for shorts right away and saw how it reads and thought WTF ? It was a Crown grounded bridge. Well that splains it...

Even if it was patented that surely has run out by now. I think most engine ers and manufacturers don't like the component count, because there is no c hip that does this.

Carvers dimmer might have been new, but the rest is just class-G (or H depe nding on who you ask)

pending on who you ask)

No disagreement here, wiki has a page on it. There are so any topologies it is ridiculous. but the light dimmer analogy is valid, it is just controlle d by an opto instead of a pot.

Until I actually worked on one and had to really look at the print I though t the commutators just switched, but it seems they got them in like a semi class C mode, conducting variably though as needed. as wondering why they didn't generate a ton of distortion. The transistor's characteristics are t he transistor's characteristics. You do not get the same gain at any Vce in almost anything I have ever seen. Some come close but I though they handle d it all with negative feedback. I think some FETs would be linear enough t o do it but it is obviously easier that way. Another approach would be to m ake the gain so damn high it could pick up a CB radio in China. That and/or high feedback is hard to tame. And I have not done the math but those thin gs have a really high damping factor I think and you don't want all that to come from the feedback, you want really solid drive to the outputs.

They got so much now. like SMPS tracking the audio keeeping ahead of it and feeding a damnear class A output stage which pretty much acts as an active filter rather than using a coil and cap. Te we got certain Crowns that are class D but with a few more components have exceeded all the others in eff iciency. I'll never find it again but I could draw it, maybe even in LTSpic e. And decades ago Sansui had their class G, which was not much unlike the Carver design.

I am started to think nothing has been really invented in a long time.

Looks like he's gone walkabout !!

Is that the same as deceased? Or maybe diseased?

John S wrote in news:qsosk2$3ts$ snipped-for-privacy@dont-email.me:

It is like what Indian chiefs do here when they are done.

Remember "MacKenna's Gold"?

Damn! This dude has a treasure map too!

Give it up, old man. The sacred burial grounds haven't taken you yet!

Was the unanswered 'Mains Power Puzzle" Phil's final insult? Mikek PS, I now someone on the group knows Phil, any news?

I was thinking maybe Bill Sloman knew him ? But Australia is still a pretty big place !

And Phil seems to try and stay pretty well hidden for whatever reason.

Say something to make him call you names, he'll slither out of the woodwork. Mikek

I've seen it but I don't remember it.

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My bet is safe, no-one got the answer.

Jason Betts was the closest.

The "Eden" amplifier uses a 25 amp TO3 style triac in series with the primary of the mains tranny.

The front panel on/off switch is a mini rocker so not rated to take the fierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resistor from MT2 to gate of the triac to do the heavy work.

Works like a charm and the switch never burns out.

Seen the same scheme used on a few audio amplifiers and PSUs.

..... Phil

new condition. It uses a 600VA toroidal tranny in the PSU.

fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitted .

mary of the mains tranny.

ierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resisto r from MT2 to gate of the triac to do the heavy work.

I got to install an AC-excited contactor on one of Cambridge Instruments to deal with the same problem.

I made a hash of it. I sized the transformer to excite the contactor on the basis of it's sustained load, and it was marginal for the load presented w hile the contractor was closing. There was room for the slightly bigger tra nsformer that would deliver enough power to reliably close the contactor, s o it wasn't as embarrassing as it might have been.

Triac in series with the transformer was what I guessed too except I was thinking that it was being used as a light dimmer circuit for voltage regulation.

Where was Phil all this time anyway ?

He sounds kind of like Trump in his attitude of knowing everything about all things audio.

Don't top post.

Phil doesn't sound in the least like Trump, not least because he comes pret ty close to actually knowing everything about a lot of audio stuff - he doe sn't say much about digital audio, so "all things audio" isn't entirely fai r.

Trump's problem is that he hasn't got the attention span to sit through bri efings that are long enough to tell him as much as he needs to know, which

- combined with excessive self-belief - encourages him to get on with doing something, when that something is frequently ill-advised (because he would n't sit still long enough to absorb proper advice).

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ar new condition. It uses a 600VA toroidal tranny in the PSU.

s fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitt ed.

r 120 amps, either polarity.

rimary of the mains tranny.

fierce inrush surge of a 600VA toroidal so it just connects a 22 ohm resis tor from MT2 to gate of the triac to do the heavy work.

to deal with the same problem.

he basis of it's sustained load, and it was marginal for the load presented while the contractor was closing. There was room for the slightly bigger t ransformer that would deliver enough power to reliably close the contactor, so it wasn't as embarrassing as it might have been.

" Man thinking how to avoid embarrassment spend more effort than when makin g same embarrassment."

.... Phil

Why not ? :)