Author Topic: Snake oil  (Read 347256 times)

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Online Specmaster

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Re: Snake oil
« Reply #1000 on: March 14, 2018, 03:06:50 pm »
It's got a class D amplifier which makes that a perfectly credible specification. I cracked it open - has a Chinese IC in it. Possible to get THD down to 0.03% easily with those. Haven't measured it but it sounds pretty excellent even with shitty Fiat default speakers. And I'm throwing Ralph Vaughan Williams' Lark Ascending performed by the Royal Philharmonic Orchestra through it which has an excessively large dynamic range and no compression.  :-+

The thing is regardless of the promises, it delivers 99% of the performance of something 1000% of the cost which makes it a good value proposition. Good job China  :-+
Pink Floyd, The Division Bell, Dark Side of The Moon etc?
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Online coppice

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Re: Snake oil
« Reply #1001 on: March 14, 2018, 03:54:19 pm »
That's a really cheap unit and I bet it would struggle to deliver the quoted power output and has sky high distortion figures and has poor frequency response to boot.  :popcorn:
OK. How much are you prepared to bet and lose?

Class D amps are an area where Chinese silicon vendors hit a home run. They came up with some really good performers which are very cheap to make. Sometimes these devices get integrated into very poor amp designs, but there are other very respectable performers which are still quite cheap. Maybe in the long term their electrolytics won't prove to have the best longevity, but on day one they work well.
 

Online bd139

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Re: Snake oil
« Reply #1002 on: March 14, 2018, 04:16:19 pm »
It's got a class D amplifier which makes that a perfectly credible specification. I cracked it open - has a Chinese IC in it. Possible to get THD down to 0.03% easily with those. Haven't measured it but it sounds pretty excellent even with shitty Fiat default speakers. And I'm throwing Ralph Vaughan Williams' Lark Ascending performed by the Royal Philharmonic Orchestra through it which has an excessively large dynamic range and no compression.  :-+

The thing is regardless of the promises, it delivers 99% of the performance of something 1000% of the cost which makes it a good value proposition. Good job China  :-+
Pink Floyd, The Division Bell, Dark Side of The Moon etc?

Been there done that. Division Bell sounds good. One of the best pieces of recording in history is the first few seconds of Lost for Words.

That's a really cheap unit and I bet it would struggle to deliver the quoted power output and has sky high distortion figures and has poor frequency response to boot.  :popcorn:
OK. How much are you prepared to bet and lose?

Class D amps are an area where Chinese silicon vendors hit a home run. They came up with some really good performers which are very cheap to make. Sometimes these devices get integrated into very poor amp designs, but there are other very respectable performers which are still quite cheap. Maybe in the long term their electrolytics won't prove to have the best longevity, but on day one they work well.

Yes exactly. The implementation is pretty amazing in this if I'm honest. I've got a NAD C340 as well and it pretty much destroys that. Sounds the same, costs and weighs a hell of a lot less :)
 

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Re: Snake oil
« Reply #1003 on: March 14, 2018, 04:32:54 pm »
It's got a class D amplifier which makes that a perfectly credible specification. I cracked it open - has a Chinese IC in it. Possible to get THD down to 0.03% easily with those. Haven't measured it but it sounds pretty excellent even with shitty Fiat default speakers. And I'm throwing Ralph Vaughan Williams' Lark Ascending performed by the Royal Philharmonic Orchestra through it which has an excessively large dynamic range and no compression.  :-+

The thing is regardless of the promises, it delivers 99% of the performance of something 1000% of the cost which makes it a good value proposition. Good job China  :-+
Pink Floyd, The Division Bell, Dark Side of The Moon etc?

Been there done that. Division Bell sounds good. One of the best pieces of recording in history is the first few seconds of Lost for Words.

That's a really cheap unit and I bet it would struggle to deliver the quoted power output and has sky high distortion figures and has poor frequency response to boot.  :popcorn:
OK. How much are you prepared to bet and lose?

Class D amps are an area where Chinese silicon vendors hit a home run. They came up with some really good performers which are very cheap to make. Sometimes these devices get integrated into very poor amp designs, but there are other very respectable performers which are still quite cheap. Maybe in the long term their electrolytics won't prove to have the best longevity, but on day one they work well.

Yes exactly. The implementation is pretty amazing in this if I'm honest. I've got a NAD C340 as well and it pretty much destroys that. Sounds the same, costs and weighs a hell of a lot less :)
When I said cheap, I meant at £22, it is cheap, I don't doubt for a moment that it is also capable of putting in a reasonable performance and when taking the low cost into consideration, its incredible really, and I for one would much rather sit and listen to it then I would that stereo in the the YouTube video  :-+ I would like to know about just how that 4 channel sound is measured, peak, music power or RMS and if it is actually capable of delivering that level of power without cooking itself as normally you need some pretty monstrous heat sinks and into what impedance?
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Online bd139

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Re: Snake oil
« Reply #1004 on: March 14, 2018, 04:49:20 pm »
Being class D, it is considerably more efficient than other amplifier topologies. The output is a PWM signal which is stuffed through a low pass filter. The MOSFET that controls the PWM is either on or off so there's as close to no power dissipation going on at all. The LPF is usually a purely reactive network i.e. L/C so there is no power dissipated there. Talking 90%+ efficiency easily. Make the traces thick, fast and low Rds(on) MOSFETs use decent inductors and you're done. Power is quoted RMS on the box into 4 ohms.

If you go back to the distant past of early 1990s, and take a look at the old MOSFET PWM RC speed controllers which are the granddaddy of the class D amps, this little bugger can shift 75A continuous and 300A peak!!! Just over an inch long. No heatsink. A lot has happened since then as well...

« Last Edit: March 14, 2018, 04:51:27 pm by bd139 »
 

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Re: Snake oil
« Reply #1005 on: March 14, 2018, 04:58:55 pm »
Being class D, it is considerably more efficient than other amplifier topologies. The output is a PWM signal which is stuffed through a low pass filter. The MOSFET that controls the PWM is either on or off so there's as close to no power dissipation going on at all. The LPF is usually a purely reactive network i.e. L/C so there is no power dissipated there. Talking 90%+ efficiency easily. Make the traces thick, fast and low Rds(on) MOSFETs use decent inductors and you're done. Power is quoted RMS on the box into 4 ohms.

If you go back to the distant past of early 1990s, and take a look at the old MOSFET PWM RC speed controllers which are the granddaddy of the class D amps, this little bugger can shift 75A continuous and 300A peak!!! Just over an inch long. No heatsink. A lot has happened since then as well...


Well there you go, thats my something new learnt for the day  :-DD
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Online bd139

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Re: Snake oil
« Reply #1006 on: March 15, 2018, 01:22:38 pm »
From Radcom this month :D

 

Offline McBryce

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Re: Snake oil
« Reply #1007 on: March 15, 2018, 01:40:03 pm »
Very funny, but it's a joke, not a real product.

McBryce.
 

Online bd139

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Re: Snake oil
« Reply #1008 on: March 15, 2018, 01:52:09 pm »
Of course it is. But it's better presented than half of the snake oil products are.
 

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Re: Snake oil
« Reply #1009 on: March 15, 2018, 02:16:08 pm »
Of course it is. But it's better presented than half of the snake oil products are.
I wonder how many people have tried to order one? Some people are so gullible that they will be asking for it, especially as it mentions RSGB members get a discount 🤣🤣🤣
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Online CJay

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Re: Snake oil
« Reply #1010 on: March 15, 2018, 02:59:34 pm »
Of course it is. But it's better presented than half of the snake oil products are.
I wonder how many people have tried to order one? Some people are so gullible that they will be asking for it, especially as it mentions RSGB members get a discount 🤣🤣🤣

I'm hoping that anyone who tries to order it gets their licence revoked.

It's a very old joke though, Pama Communications had a load of aerosol tins printed up with SWR Spray as an April fools back in the late 80s and gave them away.
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Offline Cyberdragon

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Re: Snake oil
« Reply #1011 on: March 15, 2018, 09:09:22 pm »
I would like to add to that "Alignment/Tuning Spray" and "Anti-DX Spray". >:D
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Offline djos

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Re: Snake oil
« Reply #1012 on: March 15, 2018, 10:05:38 pm »
From Radcom this month :D



 :-DD That was extremely funny!
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Offline Ice-Tea

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Re: Snake oil
« Reply #1013 on: March 15, 2018, 10:08:34 pm »
From Radcom this month :D



That's a joke, right?

Somebody please tell me this is a joke?
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Re: Snake oil
« Reply #1014 on: March 15, 2018, 10:09:36 pm »
From Radcom this month :D



That's a joke, right?

Somebody please tell me this is a joke?
Yes it's a joke
Who let Murphy in?
 

Online coppice

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Re: Snake oil
« Reply #1015 on: March 15, 2018, 11:47:34 pm »
From Radcom this month :D


Its a pity they didn't actually produce tins of that stuff. I think its something every lab should have a tin of, just so you can watch who tries applying a little of it to their problems.  :)
 

Offline Don Hills

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Re: Snake oil
« Reply #1016 on: March 17, 2018, 10:26:41 am »
That looks a lot like a can of paste flux.
 

Offline SeanB

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Re: Snake oil
« Reply #1017 on: March 17, 2018, 04:16:27 pm »
Looks more like a can of dielectric grease, actually very useful in outdoor applications to keep the plugs and sockets from corroding into a mess, though of course for best results you apply it, tighten up the plug and socket then wrap it with a layer of PVC tape and overwrap with self amalgamating tape for full weather protection.

Got the cans, got the grease........
 

Offline kjr18

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Re: Snake oil
« Reply #1018 on: March 21, 2018, 09:08:03 am »
When I connect my headphones to front panel of my pc i can hear some strange noises, even when I scroll pages or do anything. You think this can help me??? Something like this can actually work in some cases or it's total pure chinesium snake oil?
 

Offline Richard Crowley

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Re: Snake oil
« Reply #1019 on: March 21, 2018, 09:32:11 am »
I suspect that plug-in capacitor filter board actually has a chance of reducing (or removing) that kind of noise, especially if you can some how locate it close to the audio circuits.  But 50USD seems like a opportunistic price for a simple concept.

OTOH, any audio circuit built on the computer motherboard (or anywhere inside the box, for that matter) is operating in "hostile territory".  Most people who are serious about audio use external audio interfaces.  There are likely several effective choices that cost less than that board full of cheap capacitors.
 

Online bd139

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Re: Snake oil
« Reply #1020 on: March 21, 2018, 09:41:57 am »
That's quite funny actually. I wish I'd thought of it.

It's going to be no help whatsoever. Most of the noise from the headphone port on cheap PCs is due to poor design on the analogue circuits and proximity to the switching regulators resulting in pick up from the bus, power lines etc.

As a contrast, I used to have an M-Audio 2496 card inside my PC, right in the thick of the noisy problems. Nada, nothing, not a sausage. No fancy shit or capacitors here:



External DAC doesn't save you from the noise; it merely allows you to not use the lowest cost design for audio output the mobo manufacturer could get away with.
 

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Re: Snake oil
« Reply #1021 on: March 21, 2018, 10:27:47 am »
I've always used soundblaster cards made by Creative as the heart of my computer sound system and I must say that it works pretty well though expensive. I currently have a Asus with built in Realtek HD 7.1 sound system and the sound from that via my Altec Lansing ADA995 Lucas Film THX certified 5.1 speaker system with 5 channels @21w (woofer and tweeter in each) and the sub woofer 94w with 2 subs in the cabinet and the power amps weighing in at 17kg alone.

The sound from that setup is awesome and I often chuckle while listening to it because it was being offered for free on the local freecycle site a few years ago and I was the lucky sod who got it, never before heard sound like it from a computer. I know have fitted a bluray drive to the computer and often watch films on it in my workshop  :-+

Still struggle to understand how anyone could give it away, I've had it many years now and its never been any problem whatsoever, love it.  :popcorn:
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Offline kjr18

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Re: Snake oil
« Reply #1022 on: March 21, 2018, 10:47:23 am »

OTOH, any audio circuit built on the computer motherboard (or anywhere inside the box, for that matter) is operating in "hostile territory".  Most people who are serious about audio use external audio interfaces.  There are likely several effective choices that cost less than that board full of cheap capacitors.

Problem disappears when I connect headphones to the "back" (not really back as I have another audio port on top of my desk, connected with cheap cable). This card would not work, probably because the problem is flimsy cheap cables connecting hdaudio connector and front panel. So many things to go wrong in these, it's crazy.
 

Online bd139

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Re: Snake oil
« Reply #1023 on: March 21, 2018, 10:57:32 am »
Probably not even shielded cable.
 

Online Specmaster

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Re: Snake oil
« Reply #1024 on: March 21, 2018, 11:11:38 am »
Probably not even shielded cable.
I agree, by plugging the headphones in the back port, not only are plugging directly into the audio card but the PC case itself effectively becomes a screen so the headphone cable is less prone to picking up spurious signals.
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