The Audiophoolery Thread.

[Radio Wrangler]

Originally Posted by slidertogrid

The strange thing about this is that despite it being badly built and using cheap standard parts it must sound good.

What it illustrates is that making a good-sounding solid state amplifier is no longer difficult. You really do have to do something particularly bad to muck it up.

Of course, you can still make ones which sound good but which have hidden stings in their tails.... reliance on special operating precautions, going off-song as components age, just plain impromptu detonationk, and so on.

If, someone has worked hard to actually get impairments to cancel leaving only very low level residuals, then you have a system in which any small drift in characteristic in any component can spoil the cancellation, and the impairments increase dramatically. Subtractive processes can increase demands on stability hellishly.

Re Colossus... Yes, at one end of the racking in the re-creation at Bletchley, is a very nice triple-ganged variac transformer made and donated by Claude Lyons ltd. It is a monster! It is used to bring u the heater power gently. It isn't just a matter of leaving them on, it is also a matter of not shocking them at turn on, and being able to regulate their voltage.

A lot of 'high end' amplifiers discourage people going inside and they try to keep service info under lock and key... principally to stop people seeing how ordinary the innards are. Well here you have an amp planned to stop people seeing that they are rubbish.

Governments have spent billions on finding how to make electronics reliable. It's become open knowledge. It costs nothing to exploit what was hard-won. Would I pay a lot of money for something that threw it all away?

Nope!

David

[Craig Sawyers]

It started in 1963 with Leak and its Germanium transistor Stereo 30.

And ended up with this https://www.hifinews.com/content/dagostino-relentless-mono-power-amplifier

Each mono power amplifier weights a quarter ton, and costs £125k. That is right - a stereo pair is half a ton, and will set you back a quarter million quid.

And then you need a preamp and signal source of some description.

Yeesh.

Craig

I just love the bare metal mains terminals. Makes my DA90A look uber safe.

[greg_simons]

Originally Posted by knobtwiddler

https://www.youtube.com/watch?v=tKanR1aM16I&feature=emb_logo

I am in the process of heating up the rework tools so that I can replace all of those pesky NE5532s with this gem. It's a bargain at 80x the price (does it have 80 times the distortion?)

Hold the rework tools!, they might sound great in a guitar amp but not a hihi amp, plus i think he's had a bit too much of something!.
Greg.

[Ted Kendall]

Originally Posted by Craig Sawyers

It started in 1963 with Leak and its Germanium transistor Stereo 30.

And ended up with this https://www.hifinews.com/content/dagostino-relentless-mono-power-amplifier

Each mono power amplifier weights a quarter ton, and costs £125k. That is right - a stereo pair is half a ton, and will set you back a quarter million quid.

And then you need a preamp and signal source of some description.

Yeesh.

Craig

Is it for playing music or beating people to death?

In the BBC Bush House control room, there were valve distribution amplifiers which were not switched off, except for failure, in thirty years. Individual amps were made plug-in for speedy maintenenace should the need arise. During the refurbishment operation in the early 80s, the old amps were powered down rack by rack as their replacements were installed. One rack got powered down by mistake and stayed off for about an hour before being switched on again - whereupon six or seven of the eleven amps in that group failed. My name was mud with Shift Maintenance that day.

[jamesperrett]

Originally Posted by slidertogrid

The reason I say it must sound good is because whilst the purchaser cannot see inside it would have surely been demonstrated prior to purchase wet floor or not.. and surely the buyer would agree it sounded good enough to justify the price?

My experience of a somewhat similar amp (DNM) was that the owner was using it with such dreadful speakers that how it sounded didn't really matter. Apparently Dennis Moorcroft doesn't agree with screened cables so the whole system hummed pretty badly. The speakers consisted of a single driver with a whizzer cone in the centre to improve the high frequencies. Apparently losing the crossover reduces certain types of distortion but the poor reproduction of anything over about 4kHz meant that there could have been all kinds of distortion generated by the system and no-one would hear it.

[Radio Wrangler]

Relying on cone flexure (otherwise the whizzer could never move differently to the cone) is hardly going to be linear, but then that effect is less visible than crossover components you can actually see.

It's all in the mind.

Terry Pratchett called it 'Headology' when his witches were fooling people.

Some good old 50Hz hum makes yer average punter think a system is more powerful than it really is. "Just listen to the power!"

Maybe it's my impish sense of humour, but I can just imagine: "Would you put these wellies on, please, we're going into the listening room!" before the giggle-fit hits.

David

[GrimJosef]

Originally Posted by jamesperrett

... but the poor reproduction of anything over about 4kHz meant that there could have been all kinds of distortion generated by the system and no-one would hear it.

No-one who'd got to that stage in their life where they had enough money to afford the kit would hear it (OK, premiership footballers excepted).

Cheers,

GJ

[Radio Wrangler]

Originally Posted by Craig Sawyers

And ended up with this https://www.hifinews.com/content/dagostino-relentless-mono-power-amplifier

Each mono power amplifier weights a quarter ton, and costs £125k. That is right - a stereo pair is half a ton, and will set you back a quarter million quid.

And what do you get?

1) An output power meter which the designer admits is not truthful. The reviewer said it read 400W at a measured 2W out.

2) They make a point of "No Zobel"

3) At those power levels, if real, shouldn't it have its own 30A mains spur per channel, not those scoddy bits of wire under the terminals? Certainly if 4 and 2 Ohm loads are entertained.

4) 5kW toroid did the man say? For CE marking at those power levels, I thought PFC was mandatory. Certainly Bill at Linn said some of their amps were pushed into it.

A triumph of appearance and fashion.

If someone gave me a pair, would I use them? No. I wouldn't be able to stop laughing. The obvious thing would be to sell them, but the chances of finding someone sufficiently rich, yet dim means second generation riche. They'd get given to a museum of industrial design without my name as a donor.

David

[radioman]

O.A.P. Hi-Fi


Andy

[Ted Kendall]

Not far from the bandwidth of the original Western Electric recording system, and the results from that on a silent surface pressing can be incredibly lifelike.

[stevehertz]

Originally Posted by radioman

O.A.P. Hi-Fi


Andy

If there was one, I would have just just pressed the 'like' button. Or even the button.

[knobtwiddler]

And the lab results from the 125K monster suggest that it's well below Benchmark's AHB-2, at 100th of the price for a stereo amp.

To my knowledge, there are only about 2 firms still making MC meters that are even vaguely accurate (Hoyt and Simpson - even the Sifam ones now are rebadged Chinese jobs). If its meters aren't accurate, maybe they sourced them on alibaba.com... There are plenty of meters there, and they'll flap around and have pretty colours.

The mains connector...Is that legal anywhere? What if you and friends stagger back from the pub one evening for some listening to your new 250K amps, and there's an issue with the system... So, you're faffing around behind the rack, trying to work out what's wrong...wiggling the RCAs... A solution looking for a problem. Of course, terminals sound better than IEC sockets...

Our AP SYS-2722 analyser states that it needs 15 minutes to stabilise. I've never noticed worse readings on switch on, though. I think they're covering their backs. I haven't had it on for a year...the R+S ones are the workhorses. They tend to give best THD+N readings when they've been on for a while, but I haven't given thought to whether this is R+S or the DUT. Could be the latter. And modern test gear is so sensitive (when you're looking at below -100dBV THD+N), other factors such as noise sources in the bulding come into play. If I'm looking for a headline spec, I do it at the weekend, when the building is quiet.

[knobtwiddler]

>Some good old 50Hz hum makes yer average punter think a system is more powerful >than it really is. "Just listen to the power!"

A friend of mine cuts records for a living. He reckons that rumble is a large factor in why people think vinyl sounds 'fuller'. I think he could have a point. When I was a lad, and amps with sub filters were common, I always thought it sounded weaker when engaged...

[Craig Sawyers]

I have been having a recent discussion on the Linkwitz forum regarding someone who wants to extend the bass EQ of the LX521.4 (these are open baffle) to 20Hz instead of the design 30Hz. I pointed out to him that the lowest note on a bass guitar or double bass is 41Hz. You only ever need lower than that if you listen to music with a synth bass line that goes lower, or movies. In which case a subwoofer crossed over at maybe 50Hz might be desirable, rather than pushing the excursion limit on the open baffle drivers unnecessarily.

Of course there is also organ music, but any half way affordable loudspeaker cannot move enough air to reproduce low organ pedal notes realistically.

While I'm on this topic, it is next to impossible to reproduce the volume of an orchestra in full flight. A single trombone at 1 metre can generate 135dB when the player is giving it full beans, with a full orchestra capable of >120dB at typical audience position.

Craig

[Ted Kendall]

Originally Posted by knobtwiddler

>Some good old 50Hz hum makes yer average punter think a system is more powerful >than it really is. "Just listen to the power!"

A friend of mine cuts records for a living. He reckons that rumble is a large factor in why people think vinyl sounds 'fuller'. I think he could have a point. When I was a lad, and amps with sub filters were common, I always thought it sounded weaker when engaged...

Rumble, whether cut, pressed or produced by the reproducing turntable, can add an LF "bloom", particularly in stereo. Spurious, of course, and Doug Self's Devinyliser neatly removes most of this by applying a sophisticated steep cut filter to the difference signal.

[Radio Wrangler]

If you do try a movie with a pair of speakers having a serious and flat LF response, you'll really, really want to put a bass cut in. Movie soundtracks come pre-bumped at the LF end to compensate for the fact that movie moguls know no-one really has big enough speakers for the level of impression they want to make.

No cable grip, so that amplifier's very naughty with a flexible cable connected to it... Just one trip over that cable and you have bare, live, ends on the loose.

HFN&RR spoke to the designer about that meter. Seemingly his previous model had a reasonably accurate meter, but he got complaints that it didn't move much and people thought the amplifier might be faulty (obviously not trusting the evidence of their ears ) So in this model he dispensed with any pretense of accurate measurement and just made it bounce around a lot as an entertainment. An insight into what for all of us is an unaffordable world.

David

[knobtwiddler]

Originally Posted by Ted Kendall

Rumble, whether cut, pressed or produced by the reproducing turntable, can add an LF "bloom", particularly in stereo. Spurious, of course, and Doug Self's Devinyliser neatly removes most of this by applying a sophisticated steep cut filter to the difference signal.

And bless Mr Self, for presenting the theory behind his device at an AES lecture (was it 2016?). It must've been the first AES presentation pertaining to vinyl since about...

...1982?

DS is everything the subject matter in this thread is not. Sadly, this puts him in a minority in audio.

[knobtwiddler]

Originally Posted by Radio Wrangler

If you do try a movie with a pair of speakers having a serious and flat LF response, you'll really, really want to put a bass cut in. Movie soundtracks come pre-bumped at the LF end to compensate for the fact that movie moguls know no-one really has big enough speakers for the level of impression they want to make.

No cable grip, so that amplifier's very naughty with a flexible cable connected to it... Just one trip over that cable and you have bare, live, ends on the loose.

HFN&RR spoke to the designer about that meter. Seemingly his previous model had a reasonably accurate meter, but he got complaints that it didn't move much and people thought the amplifier might be faulty (obviously not trusting the evidence of their ears ) So in this model he dispensed with any pretense of accurate measurement and just made it bounce around a lot as an entertainment. An insight into what for all of us is an unaffordable world.

David

It's intriguing that he's open about this fact... 'I compromised the objective quality of the product due to demands from the peanut gallery'. Were you the cynical type, you could argue that he isn't being totally truthful, and is justifying the use of a cheap movement from Shenzhen... Movements from Hoyt and Simpson typically cost 10-20 times that of the bouncy ones from Alibaba.com... I happen to think he probably is telling the truth, albeit depressingly.

NB - in my job I have seen the same problem... I have to explain regularly to clients that a meter has to 'mean something' and have a reference for 0VU...

[The Philpott]

(Long pause, chews gum, looks at amplifier, then back at interviewer.)

'Yeah, but this one goes up to eleven'