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Old 2nd January 2005, 01:53 AM   #11
Wyloch is offline Wyloch  United States
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NEW STATUS

Got sound coming through, but it's quiet and hallow sounding. This is because I haven't grounded anything yet, from what I understand. How do I ground the thing? I know I've got to ground the in and out jacks and the pot (which I've not implemented yet anyway, so I'll worry about it later), as well as the "virtual ground." What exactly is the virtual ground? I'm using Tangent's plans, with the 0170 board. I'm using the RS 274-0246 jacks. They have five pins, but I'm pretty sure I know which is the ground. Sum up - how do I ground the board?
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Old 6th February 2005, 05:07 AM   #12
lomtik is offline lomtik  Canada
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What wire gage is good for the project?
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Old 19th February 2005, 06:44 PM   #13
lomtik is offline lomtik  Canada
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Quote:
Originally posted by Wyloch
NEW STATUS

Got sound coming through, but it's quiet and hallow sounding. This is because I haven't grounded anything yet, from what I understand. How do I ground the thing? I know I've got to ground the in and out jacks and the pot (which I've not implemented yet anyway, so I'll worry about it later), as well as the "virtual ground." What exactly is the virtual ground? I'm using Tangent's plans, with the 0170 board. I'm using the RS 274-0246 jacks. They have five pins, but I'm pretty sure I know which is the ground. Sum up - how do I ground the board?
I've recently completed my amp.
Virtual ground is a point between capacitors on the schematic, so that if you place the negative terminal of your potentiometer there and the positive at positive side of capacitor, you'll get V/2 voltage (i.e +4.5V for 9V battery).
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Old 22nd March 2005, 07:16 PM   #14
Bose(o) is offline Bose(o)  Canada
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Alright, I'm not a noob and I'm having problems working with the circuit on my breadboard. Odd, since in theory most things will work on a bread board and not work on the chosen chassis.

Anyone available to help? I have access to any electrical equipment you can dream of, so shoot.
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Old 22nd March 2005, 09:38 PM   #15
Wyloch is offline Wyloch  United States
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Wow. My very first thread ressurected.

What exactly is the problem? You vaguely mentioned the chassis - does the amp not work when hooked up to the panel components?
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Old 23rd March 2005, 01:30 AM   #16
Bose(o) is offline Bose(o)  Canada
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I'm going to re-re-build the amplifier circuit on my bread board and re-re-read the article from Chu Moy to better understand the separate components, though, I'm sure I understand the application of the components.

I'll post up, with a report.
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Old 23rd March 2005, 02:07 AM   #17
Bose(o) is offline Bose(o)  Canada
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Alright, so I've removed R1 from the input because I don't need the attenuation since I'm not making any recognisable sound anyway. I've found that the DC blocking section is more or less causing a square wave type sound.

I have all grounds on the amp-section schematic connected to teh virtual ground. The audio ground is connected directly to the headphones. I'm using a gain of 11 and my power supply is using only 100uf caps (this ain't the problem), the supply is split relatively well +/- 0.02V

I've done far more complex stuff than this, so it's really bugging me to death here.
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Old 23rd March 2005, 02:40 PM   #18
Wyloch is offline Wyloch  United States
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Read this too. Might help.

http://www.tangentsoft.net/audio/cmoy-tutorial/
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Old 23rd March 2005, 02:59 PM   #19
Bose(o) is offline Bose(o)  Canada
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Well, I've taken everything out of the input chain, no attenuating resistor or DC blocking, but of course there is still the feedback loop.

I can get the chip to play for half a second or so while the supply is charging up and for a tenth of a second while the battery is being disconnected. I doubt that the op-amp would not enjoy more voltage or current. After that it's all about distortion and volume is -600 x what I've put in. It's like I'm using a subtractive and distorted filter.

thnx Wyloch, I've read that quite a few times already. My headphones are Bose triports and Sennheiser HD433s both are 32-ohm 'phones.
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Old 23rd March 2005, 03:40 PM   #20
Bose(o) is offline Bose(o)  Canada
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I've added bypass caps (0.1uF) on the power supply pins like the TI datasheet suggested and checked current draw. Every single thing is within spec.

If I change R3 absolutely nothing happens to the sound, same whisper quiet distortion.
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