Possibly the most ridiculous scam Ive seen in audio

[avian]

Ok I cant keep it in any longer, I'm frustrated and need to vent , and Ive come to the only place where people would appreciate just how insane what Im about to say is.

Im guessing the majority here know what a common cathode circuit is, and the basics of how to calculate its various components, if you were using say a 6922 or similar.

But imagine this situation if you will.. Now I'd like you all to pretend there is a magical land, where an amazing voodoo designer has built a TDA1541 based dac using generic easily available PCBs (not of his design), coupled with a simple 6922 - with both triodes in parallel wired as a common cathode. I also want you to pretend this manufacturer is charging around $5000 for this dac. One day in this fantasy land this manufacturer is asked what the output impedance of his dac is. This simple question causes great confusion, and results in the designer and his minions coming up with about 5 wildly different figures, some of them derived from webpages that work it out for him. This designer sadly didnt manage to use this website correctly, nor bother reading any text on tube design such as morgan jones or similar.

The designer and some clients then notice his choice of coupling caps (200V Duelunds) are dying. And to "his amazement", didn't know B+ would be applied across the cap during start up and didnt rate the cap appropriately. But "its okay" the designer says, let us all buy higher rated duelunds and keep our 200V ones for something else in the dac that we will conjure up shortly.

One of the merry little minions that admires this designer has decided to follow in his footsteps, and try to create an amazing clock to go with the dac. After looking around he found someone on eBay selling kit LM317 boards and decided it was a good place to start. But what to do with those generic power supply caps? I know, lets replace them with duelunds! His product is now complete, an LM317 powered crystal, with duelunds in the power supply. The designer and all the other minions celebrate in joy.

In this magical world, people are still interested in the dac and clock, that these stunning examples of engineers have produced, and happily ignore the fact none of them know what they are doing, and by building and selling equipment, they are putting homes and lives at risk. Sound too far fetched to be true? think again!

[wwenze]

Link please?

[Xoc1]

If it is true then I don't see why you should not supply us with a link so that others can check it out. Obviously the designer is not embarrassed by his product. So what is to be gained by denying the rest of us the chance to check it out and give a second opinion.

[avian]

Originally Posted by Xoc1

If it is true then I don't see why you should not supply us with a link so that others can check it out. Obviously the designer is not embarrassed by his product. So what is to be gained by denying the rest of us the chance to check it out and give a second opinion.

Sure. The product is the "KillerDac". They dont have their own product page, but they do have their own forum, a bunch of paying customers, and the attention of many on stereo.net.au forums.

Dying duelunds due to being run out of spec -
duelund caps issues

A super clock made with an lm317 and duelund caps -
kajak12; diy clock

Confusion over the output impedence of this killer $5000 dac -
Lightspeed Attenuator

[AndrewT]

except for George dropping in to help these "Blind leading the Blind" tribe, it appears that "Killer Dac" could well be a very appropriate title.

[Greg Erskine]

hi avian,

I know exactly what you are referring to and understand your frustration. I have been spent the last few days looking at TDA1541 and 6922 datasheets, SRPP circuits, Lampizator, Tube CAD Journal etc.

There is no scam going on here. The people involved have the opportunity to hear this DAC (and compare) before they layout their money. I have meet a few of the people involved (including the designer) and they are genuine, well meaning people IMHO. You need to let it go.

This DAC also won a recent shootout (almost unanimously) to people that had little previous knowledge of what they were listening too.

BTW: The technical issues you refer to do seem hard to comprehend and understandably raise alarm bells among engineering types.

regards

[AKSA]

This is no scam, but it is overpriced. I know well the background of this product, it's been put together from an original design done right here in Melbourne, with input from a good friend who is outstanding technically.

It is very easy to condemn anything if it seems expensive. And it is no effort at all to question something that a lot of passionate people say 'sounds good', particularly in the absence of technical measurement, which may or may not relate to the quality of the sound.

OTOH, very few technical types can explain why things sound as they do. I think this sort of criticism therefore cuts both ways.

Hugh

[avian]

Im not questioning its sound, Im questioning the ability of the designers to put together a product that is safe, and wether or not something like this should even be on the market in such a condition.

Nothing to do with the whole measurement vs sound debate thats been rehashed in other places countless times.

I tried to keep my vent as short as I could, I omitted details such as solid core cat5 being used to carry large current bending around little posts (you know how cat5e has that nagging 1m radius spec unlike any cable that can safely be used to carry current).

I ask what wouldve happened if one of those duelunds failed when used with a solid state pre/amp combo that can pass DC to the speaker terminals? Heck do you even know if they have wired ground/earth in a way thats safe?

For $5k, Id not only expect the product to not damage itself, Id expect it to not damage equipment around it, people around it, and perhaps have a rating or two to show its tested and safe for consumer use.

[AKSA]

Avian, that's a fair call. I will speak with my Sydney friend, see if he can influence the safety issues you refer to. Certainly they should be resolved swiftly, no argument there, but since we assume a properly earthed and fused trafo lies between the mains and the audio circuitry the danger is not so great as it could be, for example with power tools.

Hugh

[AndrewT]

Originally Posted by AKSA

........ since we assume a properly earthed and fused trafo............

is that a fair assumption in view of the apparent lack of basic electricity knowledge among the tribe members?