pabbi1

Blue Hawaii Special Edition

1,439 posts in this topic

On 4/14/2016 at 6:08 AM, jpelg said:

Would strategically placed silica gel packets help?

That's actually brilliant.

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Although the KGSSHV in question is one of Geoff’s beautiful builds I doubt there is any stupidity in there. :D

5 hours ago, spritzer said:

If you do something stupid then the KGSSHV has more than enough potential to fry any Pro bias headphones. 

Edited by johnwmclean

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It has nothing to do with the build, it's built in into the circuit.  Any peaks that are double the bias voltage will run a high risk of damaging the drivers.  That's why the old transformers were fitted with clamp circuits.  Run an active preamp into the KGSSHV and you can have enough gain for this to happen...

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13 hours ago, spritzer said:

If you do something stupid then the KGSSHV has more than enough potential to fry any Pro bias headphones. 

What kind of "stupid" are you talking about here?

1 hour ago, spritzer said:

It has nothing to do with the build, it's built in into the circuit.  Any peaks that are double the bias voltage will run a high risk of damaging the drivers.  That's why the old transformers were fitted with clamp circuits.  Run an active preamp into the KGSSHV and you can have enough gain for this to happen...

 How would a clamp circuit help?

 

 

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Both of those are very obvious... :huh:

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so with any fully dc coupled circuit, if you put a balanced signal on both inputs say -1 volt, the output of both drivers will go to -VCC (400,450...)

resulting in a dc bias on the headphones of 1kv

early srm717's had a protect circuit for this, but it did not work as the relays ended up arcing thru.

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What about having a simple circuit that loads down the BIAS voltage if excessive DC is present on the output?

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not a good idea to do that to the diaphram

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19 minutes ago, kevin gilmore said:

not a good idea to do that to the diaphram

also if the "load" is placed before the 4.7M balast resistor? 

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23 hours ago, spritzer said:

If you do something stupid then the KGSSHV has more than enough potential to fry any Pro bias headphones. 

No idea what caused the failure in my 009s. It was the left driver that started fading output. No distortion and the right driver was ok. I don't think it was the amp, but I will measure the bias value anyway from the pad on the PS board, and the DC offsets at the socket.Most probably it is the dreaded 009 imbalance thing again. The only thing in my car is it took 23 months to appear, most cases I have heard about happen inside 3 months.

My input is actually an RCA line out of 2V standard into a convertor plug RCA/XLR so actually is less than the expected 5/6v of an XLR input. I ran the pot at around 12 o'clock for loud listening, 11oclock for normal.

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Visiting Osaka, and it seems they take thier audio very seriously here. Running a Blue Hawaii is not simply a choice, but a Lifestyle! 

IMG_1112.JPG

5 people like this

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Any hint about what Justin is cooking ?

Ali

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Knowing Justin, probably burgers.

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So he's sending me something...  ;)  He'll get that joke...

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