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Old 6th Aug 2020, 5:55 pm   #1701
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Default Re: The Audiophoolery Thread.

I have just ordered the most expensive resistor I have ever, a 100W 10 ohm wire wound free air job, that was 19 quid. Saved a lot of money and time, the other chap was going to go for a metal clad and a heatsink. Same money for a two watter, you are 'avin a larf!
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Old 6th Aug 2020, 6:57 pm   #1702
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Default Re: The Audiophoolery Thread.

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... Right. I am talking about common or garden solid state hifi amps, not esoteric valve stuff which are greatly outnumbered by the former by a massive magnitude. So, for me, given what I've just said, amp speaker matching is largely (not uniquely) an audiophoolery thing.
I don't know how common common or garden solid-state hifi amps are these days. I suspect you'll find the old-fashioned sort have been almost entirely wiped out in the general public's homes by computer and phone audio. However if you have a number for their sales, greatly massive or not, I'd be genuinely interested to hear it.

In the meantime you restarted this thread after it'd been slumbering for a couple of weeks with a report on your visit to an audio forum. I don't know which one it was but again I suspect you'd have found more valve amp owners there than you might imagine. It's any kind of hifi ownership at all that's 'esoteric' these days, not whether the active medium is vacuum or silicon.

By way of a check I thought I'd look through the last 3 issues of HiFi News (Jul-Sept) and see what modern power amps look like these days. I think HFN is the largest circulation mag (but please correct me if that's wrong) so maybe it represents the hifi community best ? The ones reviewed were

Musical Fidelity M8xi - Solid State but not exactly common or garden at 940W/ch into 4ohms

Vinnie Rossi L2i-SE - Solid State but with a 300B triode gain stage which can be switched in and out, so really it's a Hybrid

Arcam SA30 - Solid State with what the manufacturers call a Class G output stage, although it seems it's really a type of Class AB, 220W/ch into 4ohms

NAD M33 - Solid State Class D (strictly UcD), 430W/ch into 4ohms

Copland CSA100 - Solid State but with just one valve in there (a 6922) which can't be switched out, so we do have to label this a Hybrid, 180W/ch into 4ohms

Ayre AX-% Twenty - Solid State but with an esoteric output stage (Diamond Circuit - patented by MIT in the 1960's apparently), 250W/ch into 4ohms

Emotiva XPA HC-1 - Solid State with the manufacturers now calling the output stage Class H, but it seems it's much the same as Class G (see above), 415W/ch into 4ohms

So four were Solid State and two were Hybrid. I was genuinely surprised there wasn't an all-valve one in there, although we are promised the EAT E-Glo i tube for next month. But I don't think the silicon ones were exactly conventional ... .

Cheers,

GJ
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Old 6th Aug 2020, 7:15 pm   #1703
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Default Re: The Audiophoolery Thread.

Why do they all have such ludicrous power output capabilities?

Alan
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Old 6th Aug 2020, 7:20 pm   #1704
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Default Re: The Audiophoolery Thread.

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Let's shoot a sacred cow. What gets called Damping Factor in an amplifier isn't. If you designed an amplifier with zero output impedance, it would be as perfect a voltage source as you could want. It is impossible to dissipate energy in a zero resistance, so it CANNOT do any damping at all. THe damping of cone motion at resonances come from the resistance of the voice coil, crossover windings, wiring.
I'm glad you pointed that out David.....
Craig
Yes, thanks from me too - I've torn my hair out in the past trying to convince folks of this fact.

Steve.
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Old 6th Aug 2020, 7:25 pm   #1705
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Default Re: The Audiophoolery Thread.

In response to David's point on crossovers, there is a rather tricky crossover approach based on conjugate impedances, which means that the load on the amplifier is very close to resistive. Lots of parts are needed to make this happen.

KEF went this route at one stage with massively complicated crossovers.

This shows the sort of approach needed with modern software, and the complexity of the resulting crossover. They say that a conjugate crossover will cost as much as the drivers, or even more.

https://www.physical-lab.com/images/...ShopApp_04.pdf

Craig
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Old 6th Aug 2020, 8:05 pm   #1706
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Default Re: The Audiophoolery Thread.

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Why do they all have such ludicrous power output capabilities?
I'd guess because power is dirt cheap and a bit of a selling point - no-one wants to feel that their amp might be struggling. In fairness most of them are only 3-6db more powerful than the very respectable Quad 405, which was released in 1976.

Modern valve amps tend to be in the tens of watts per channel, although there are single-ended triode ones delivering just a few watts and also the odd behemoth (parallel push-pull, mostly) capable of a few hundred watts.

Cheers,

GJ
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Old 6th Aug 2020, 10:08 pm   #1707
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Default Re: The Audiophoolery Thread.

Living in the RF world, I have to do a lot of conjugate matching.

One trick is to design an impedance transforming network to go between a transmitter's output transistor and the antenna feeder. There is a filter after the transforming network to stop harmonics getting radiated by the antenna. However, if you design the filter and the transforming network together, you can present impedances at each harmonic which reflect the harmonic energy with such a phase shift that the chopping action of the sort-of-class-C transistor transletes the harmmonic energy back to the fundamental frequency in phase with what is being transmitted!

In theory, a perfect class C stage can just reach 66.6666% efficiency. The harmonic recycling trick can push this to well over 80% and this is at over 100MHz. The difficulty is keeping it on song over a needed bandwidth.

Circuits like crossovers are used to split the signals from a single, multi-band antenna amongst several quite different receivers. Because there are cables and filters on the go, you need to be able to do the splitting while maintaining good impedance matches at all ports.

.................................................. .....................

Valve amplifiers clip smoothly, progressively and don't sound terribly bad.

Good transistor amplifiers clip abruptly and then come out of clipping after the overdrive has ended. This does not sound good. So it is usual for transistor amplifiers to be sized much larger than valve ones for the same job.

Bad transistor amplifiers clip abruptly and then get hung up for much longer than the overdrive. They can recover with bumps and lurches. This really sounds awful, so they need sizing to never get into this area. If you chose to design with transistors, it is relatively easy to design for ridiculously high power, but then, there are reasons for doing so.

Bob Carver designed some amplifiers with excessive looking power supply foltages. They could give dramatic amounts of power for short transients, but neither the power supply nor the heat sinking were man enough to keep it up for long. It was a case of designing around the probability density function of power in sound. I suspect they would melt down with some of the processing applied to today's programme material.

David
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Old 7th Aug 2020, 10:58 am   #1708
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Default Re: The Audiophoolery Thread.

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There are two reasons that Option 1 was not a commercial success. First, it was expensive - about 2.5 times the price of a Quad ESL63 at the time - so around £6k to £8k in the mid-late 80s, so around £18k - £25k in today's prices. It was more than an order of magnitude more expensive than any other Wharfedale speaker.

So there was a stigma attached to having a Wharfedale speaker costing that much. There was certainly competition at that price point from Magnaplanar, Martin Logan, Apogee etc that were also dipole speakers with no brand baggage.

Therefore Wharfedale missed a trick. Creating a special brand name for Option 1, and possibly a range of speakers and amplifiers at a high price point.
And Option 1 was a truly awful name for a loudspeaker!

By the time I came on the scene it had been discontinued. They retained one pair, and it sounded superb, with spookily accurate imaging. I think they sold less than ten pairs all told. At a time when the Diamond (probably III) was selling 50,000 pairs a year.

Craig
That's interesting to hear from someone who has first hand experience of the Option One - they've always fascinated me. It seems that Wharfedale weren't the only more budget-oriented company who were experimenting with posher stuff at the time, as Goodmans came up with the 'Graduate' series of two different speaker designs plus a subwoofer unit around the same time - a pair of Graduate Alphas cost £500 when the Mezzos were £130.

Sadly, they were reviewed in an A5 Hi-Fi Choice and the conclusion was that, although they showed promise, the Mezzos sounded better! It seems that they were dropped after this as they never appeared on the market and were seemingly never spoken of again. My efforts in trying to find out anything more about them has drawn a complete blank.

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Originally Posted by mark_in_manc View Post
B&O had a rather nifty product which tried to do something like this by measuring its own radiation impedance - the acoustic impedance (pressure / velocity) looking into the room at the location of the source - using not a mic and accelerometer, but a single mic which moved out on a motorised 'stick', to provide an impedance estimate based on a two-microphone finite difference velocity approximation. I suppose this would be around late 1990s, and if I remember correctly, it was on sale in shops.
This wasn't a standalone product but a facility built into the Beolab 5 loudspeakers for room tuning below 200Hz.

https://beocentral.com/beolab5
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Old 9th Aug 2020, 3:36 pm   #1709
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Default Re: The Audiophoolery Thread.

I tried to attach the Option 1 instruction manual, but it is far too big for the forum. And being a pdf does not zip down more than 10% or so.

If anyone is remotely interested in this fascinating piece of audio history, pm me your email address and I send you it.

Craig
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Old 9th Aug 2020, 5:09 pm   #1710
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Default Re: The Audiophoolery Thread.

A user manual for the Option 1 can be found here: <LINK>

Cheers
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Old 9th Aug 2020, 5:27 pm   #1711
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Default Re: The Audiophoolery Thread.

I'd not come across them before this.

Quite a bold move to market them, and sufficiently outlandish that few people would buy them without hearing them, and few of those people would have been able to have afforded them. Multiply in that only a proportion of people who could afford them and did come across a pair on demo would like them, and they wouldn't catch on.

David
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Old 9th Aug 2020, 11:50 pm   #1712
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Default Re: The Audiophoolery Thread.

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A user manual for the Option 1 can be found here: <LINK>

Cheers
Thanks for finding that - not sure where I downloaded mine. Could have been from there.

Craig
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Old 10th Aug 2020, 4:26 am   #1713
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Default Re: The Audiophoolery Thread.

For younger people the tool of choice for music seems to be the telly with a sound bar or mobile phone or iPad in the home, or phone linked into a car system on the road.

Subscription services are replacing record and CD collections. CD shops seem to have vanished apart from the same easy listening titles in every larger supermarket.

Mr Consumer seems to be stuck with switch-mode amplifiers and dodgy marketing claims intended to move their class letter as close to the end of the alphabet as possible.

Serious hifi has been subsumed by the esoteric 'high end' with all it's amusing claims.

It looks like there is a large hole in the market. Is no-one making straight-forward class A-B stuff anymore?

It's quite apparent that the majority of people have never heard high quality sound reproduction. Visitors point to the pair of transmission line speakers in my lounge and ask about them. A simple demo of nothing spectacular, whatever is in the CD machine at the time, usually causes surprise bordering on amazement.

David
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Old 10th Aug 2020, 4:54 am   #1714
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Default Re: The Audiophoolery Thread.

People can often hear good sound reproduction in cinemas these days, both indoor and outdoor, if it's set up correctly. Some of the best sound I've heard has been at outdoor cinemas where there is little to no room contribution.

On the other hand, some of the worst has also been at cinemas where say the sub woofer system has not been balanced against the rest of the system. So often the gear is fantastic and it's, sadly, the local technicians who dont seem to know what they are doing, or are not called in because the problem is not reported to them by the staff, who in some cases are generous volunteers who not only sell tickets, run the drinks and sweets bar but also press the "go" button to start the projection.
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Old 10th Aug 2020, 6:24 am   #1715
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Default Re: The Audiophoolery Thread.

I note well TIMTAPE's comment re sub woofers!! I have YET to hear a system where they are not clipping continuously. I also find digital cinema to have just as bad clipping of the video!! the picture flicker is horrible to watch and hurts ones eyes. Dolby Audio is similar!! you can hear the car keys rattling EXACTLY as car keys do. Gravel crunching under a leather soled shoe is EXACTLY as gravel sounds under a shoe. Normal speech is more like Blubbly garbleba. Which as everybody knows means Dolby Audio ®.
AHH the wonders of modern science ??

Joe
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Old 10th Aug 2020, 7:44 am   #1716
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Default Re: The Audiophoolery Thread.

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It looks like there is a large hole in the market. Is no-one making straight-forward class A-B stuff anymore?

David
Among others https://emotiva.com/pages/gen3-amplifiers . Their stereo 300 WPC (why do even they use "RMS power"?) version is just shy of $1000, although they do both lower cost and higher cost versions. They do 5 or 7 channel modular versions for home cinema (or powering active speakers).

They have moved away from a monster toroid and regular supply to a chunky switched mode unit, and dynamically switched power rails. So it is conventional AB, with a bit of class H too.

They used to provide a link to Audio Precision plots of their amp's performance, but they seem to have discontinued that. Too much information to confuse the public.

They also of course quote the useless "damping factor", which as we've already discussed is a useless number.

Craig
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Old 10th Aug 2020, 10:39 am   #1717
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Default Re: The Audiophoolery Thread.

Thats a spelling mistake Craig!!,, Its really DUMPING factor

Joe
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Old 10th Aug 2020, 2:21 pm   #1718
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Default Re: The Audiophoolery Thread.

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It looks like there is a large hole in the market. Is no-one making straight-forward class A-B stuff anymore?
Off the top of my head:

Cambridge Audio
Naim Audio
Exposure
Yamaha
Sony
Leema
Marantz
Denon
Densen
Electrocompaniet
NAD
Pioneer
Rega
Primare
Tangent

There are many others but I kept it to companies that make stuff with reasonably sane price tags!
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Old 10th Aug 2020, 4:05 pm   #1719
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Default Re: The Audiophoolery Thread.

But are they shifting that much product? considering the prevalence of phones. I fear many on that list are close to the edge.

The phones are even close to taking out the camera makers.

David
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Old 19th Aug 2020, 4:36 pm   #1720
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Default Re: The Audiophoolery Thread.

The speakers are drop dead gorgeous (and a normal house mortgage price). Add an array of subwoofers and you talking a million quid.

But look at the cable prices further down the page

https://audiofederation.com/brands/k...rma-price-list
https://kharma.com/

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