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Headamp Blue Hawaii Special Edition - Page 299

post #4471 of 6625
Quote:
Originally Posted by kevin gilmore View Post
 

spritzer and I ended up with about 500 fake parts from dalbani

(nikko-electronics.co.uk) very bad people to deal with.

they eventually replaced the parts with real parts, but charged

us additional to do so.

that is such ******** - how can they get away with that. Do you know straight away if the parts are fake? Is there a way of testing. Could they potentially ruin a build if it went unnoticed?

post #4472 of 6625

my understanding is the problem is much worse recently as the high V parts for CRT drive are discontinued, official distributor stock depleted

 

so for a build with parts bought 2-3 years ago the parts are more likely to be correct than if bought today

post #4473 of 6625

there are 2 transistor device testers you can buy on ebay that can verify

these devices. one measures beta and high voltage breakdown and the

other measures gate capacitance.  So for about $80 total, you are good

to go. Justin, and I have real curve tracers in addition because telling

real input jfets from fake switching input jfets is a lot tougher.

post #4474 of 6625
Quote:
Originally Posted by jcx View Post
 

my understanding is the problem is much worse recently as the high V parts for CRT drive are discontinued, official distributor stock depleted

 

so for a build with parts bought 2-3 years ago the parts are more likely to be correct than if bought today

 

dont forget all the low noise jfets 

HeadAmp Audio Electronics - home of the Pico and Gilmore amps.  Now with Audeze, Fostex, HiFiMAN, Sennheiser, and STAX.
Find us at www.HeadAmp.com

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post #4475 of 6625
Quote:
Originally Posted by magiccabbage View Post
 

that is such ******** - how can they get away with that. Do you know straight away if the parts are fake? Is there a way of testing. Could they potentially ruin a build if it went unnoticed?

 

several ways.

 

1) appearance, if you know what a real part looks like, the fake parts are usually different. however often the photos will show real parts.

2) basic tests with a transistor tester for max voltage, and gain, and of course assuming the pin-out is the same.

 

if you get this far and the part tests good, it will probably work in the circuit, just not to the same specifications which could mean higher noise or frequency response issues. there are probably many working amps out there with fake parts. 

 

as an example this is a fake 2SK216, a part used in the BHSE: http://www.ebay.com/itm/1pcs-2SK216-TO-220-Silicon-N-Channel-MOS-FET-/181048422761?pt=LH_DefaultDomain_0&hash=item2a2753b169

 

i have notified ebay about it and also asked the seller to remove their listing, but it has not has happened. you will see these have been sold and the buyers have left positive feedback, but they are very fake parts.


Edited by justin w. - 12/19/13 at 11:28am

HeadAmp Audio Electronics - home of the Pico and Gilmore amps.  Now with Audeze, Fostex, HiFiMAN, Sennheiser, and STAX.
Find us at www.HeadAmp.com

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post #4476 of 6625
Quote:
Originally Posted by justin w. View Post
 

 

several ways.

 

1) appearance, if you know what a real part looks like, the fake parts are usually different. however often the photos will show real parts.

2) basic tests with a transistor tester for max voltage, and gain, and of course assuming the pin-out is the same.

 

if you get this far and the part tests good, it will probably work in the circuit, just not to the same specifications which could mean higher noise or frequency response issues. there are probably many working amps out there with fake parts. 

 

as an example this is a fake 2SK216, a part used in the BHSE: http://www.ebay.com/itm/1pcs-2SK216-TO-220-Silicon-N-Channel-MOS-FET-/181048422761?pt=LH_DefaultDomain_0&hash=item2a2753b169

 

i have notified ebay about it and also asked the seller to remove their listing, but it has not has happened. you will see these have been sold and the buyers have left positive feedback, but they are very fake parts.

incredible, what goes on under your nose. 

post #4477 of 6625
Quote:
Originally Posted by magiccabbage View Post
 

that is such ******** - how can they get away with that. Do you know straight away if the parts are fake? Is there a way of testing. Could they potentially ruin a build if it went unnoticed?

 

When I got the parts I just put them into storage without giving them a second glance.  I had enough 2SA1968's at hand for the time being so it was a few months until I dug out the stash and realized they were all fake.  Dalbani spun some BS that I should have tested them on arrival but a quick reply stating that when dealing with reputable suppliers that isn't needed.  I've never had to test any part I've gotten from Mouser to see if it was real or not. 

post #4478 of 6625
Justin, can you comment on how components have changed (eg, using one brand of cap vs another), over the build lots?
Is this current lot using the same component brands that you used for the previous runs?
post #4479 of 6625
Quote:
Originally Posted by Surge74 View Post

Justin, can you comment on how components have changed (eg, using one brand of cap vs another), over the build lots?
Is this current lot using the same component brands that you used for the previous runs?

 

yes

HeadAmp Audio Electronics - home of the Pico and Gilmore amps.  Now with Audeze, Fostex, HiFiMAN, Sennheiser, and STAX.
Find us at www.HeadAmp.com

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post #4480 of 6625

I like it when Justin says the "yes" word.

post #4481 of 6625

After months of simply enjoying my system, with  no changes or tweaks, my tranquillity has been shattered by the most unnerving thing: Yep, it's the dreaded...…UNEXPLAINED NOISE :eek:.  In around 2 decades of Stax ownership, I've never had an Unexplained Noise before (discounting the Stax fart, obviously), so I'm quite worried about it.

 

It sounds like a sharp click, like a static discharge or pulse on the line, always in one channel. Hours may go before it happens, but when it does it's most likely to repeat within seconds. It's not the source and it doesn't appear to be affected by volume control, but it hasn't happened often enough for me to be sure. There is no channel imbalance and the SQ is fantastic. There was nothing unusual about heat or humidity when this problem started.

 

So suggestions please Sherlock on the most likely culprit?

 

To my mind it must be one of: the tubes, the BHSE or the headset. As my 007 Mk1 is the only electrostatic headset I have, my swapping options are limited. Removing and shorting the 007's pins made no difference.

 

I'm hoping it's the tubes because they are the easiest to replace. And these are the Psvane PH's after all, with their suspect quality control. So last night I pulled out the PH's (very carefully) and pushed in the Treasures. Result was no clicks that evening. But to be conclusive, I should swap the PH's back in to see if the noise returns. My question is: would it be very, very unwise to put the PH's back in? I.e. is the Unexplained Noise a warning of imminent tube failure?

post #4482 of 6625

Unexpected noise is most often one of two things, debris has found its way inside the drivers or the tubes are acting up. 

post #4483 of 6625

swap the tubes to the other channel and see if the noise moves with it

HeadAmp Audio Electronics - home of the Pico and Gilmore amps.  Now with Audeze, Fostex, HiFiMAN, Sennheiser, and STAX.
Find us at www.HeadAmp.com

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post #4484 of 6625

Doh! Good point Justin. I'll give it a try tomorrow.

 

One thing I should point out when going back to the Treasures after a long gap: It's confirmed that the PH's are still on a higher plain on the SQ front.


Edited by TheAttorney - 12/22/13 at 4:54am
post #4485 of 6625

well please let us know how Rachel responds to your questions about quality control.  I believe she sent a 32 page instruction manual to the boys in Hong Kong detailing how to test those tubes. Be careful of asking how she monitors compliance from Canada if she never actually touches the tubes that she sent to you. 

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