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Headphone Systems Everything to do with Headphones

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Old 19th August 2014, 08:03 AM   #11
awty is offline awty  Australia
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Whats the output impedance rated to?
Will it work ok on 120ohm Headphones?
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Old 9th September 2014, 05:10 AM   #12
awty is offline awty  Australia
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Well the answer is yes.......just
Although the AKG's took about 50 hours to come good.

I built this amp's case out of junk I had in my scrap metal pile. Its going to be a gift for my son. VU's are cool.
This amp sounds very good, for what its worth......very happy.
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Old 9th September 2014, 08:15 PM   #13
MrSlim is offline MrSlim  Canada
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Quote:
Originally Posted by awty View Post
Well the answer is yes.......just
Although the AKG's took about 50 hours to come good.

I built this amp's case out of junk I had in my scrap metal pile. Its going to be a gift for my son. VU's are cool.
This amp sounds very good, for what its worth......very happy.
Very Cool Steam Punk look..
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Old 9th September 2014, 10:26 PM   #14
awty is offline awty  Australia
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Thanks, more junk than punk, but fun to build.
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File Type: jpg headphone amp 3.jpg (85.6 KB, 159 views)
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Old 10th September 2014, 06:49 PM   #15
phase is offline phase  United States
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I like it.
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Old 15th September 2014, 05:17 PM   #16
sfthurber is offline sfthurber  United States
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Originally Posted by ljm_ljm View Post
Does not need to be connected to earth, yellow green wire.

Only need to connect the power. Disconnect the line.

PCB through the screw and wire.

Normal HA-PRO connection. Signal to noise ratio is very good.
i see that the board has a relay and some circuits for the relay.
what are the protection features?
delay start?
over-voltage?
loss of one power rail?
etc.
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Old 15th September 2014, 05:29 PM   #17
sfthurber is offline sfthurber  United States
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Quote:
Originally Posted by awty View Post
Whats the output impedance rated to?
Will it work ok on 120ohm Headphones?
it is almost certainly OK.
but ultimately it depends on the voltage swing you need.
it goes roughly like this:
let's assume that 1.2 volts RMS is enough for the SPL (loudness) you want.
at 120 ohms the output current would be 10 ma and the output power would be 12 mw.
this is well below the board designer's claimed max current of 150 ma (at which point the opamps would still be considerably below their ratings for both current and power output).
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Old 22nd November 2014, 03:51 AM   #18
proid is offline proid
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Is the first stage inverting and the second stage non-inverting? So the output is inverting? Is that fine when powering a headphone? Sorry my knowledge is very limited
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Old 16th December 2014, 08:42 AM   #19
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by sfthurber View Post
i see that the board has a relay and some circuits for the relay.
what are the protection features?
delay start?
over-voltage?
loss of one power rail?
etc.
Yes it is . It has a DC voltage protection , as well as delay function. Of course, I recommend switching above 275V104 a capacitor in parallel . Thus even better , you can eliminate off sparks, abnormal noise voltage generated .
If you turn off the power does not generate abnormal noise, then you can ignore it .

Last edited by ljm_ljm; 16th December 2014 at 08:45 AM.
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Old 21st January 2017, 01:26 AM   #20
snoweater is offline snoweater
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Hello,
How did you configure the vu meter with the amp. Do you have separate DC power source for the VU meter?

Hopefully waiting for your reply.
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