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Low levels on line-out?
Low levels on line-out?

New MessageLow levels on line-out? (modified 0 times) Booker
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So I just finished the line-out mod from www.retina.net/~jna/iopener, and it seems that the levels are very low - i.e. if I A/B between my CD player and the iopener, I can barely hear the iopener at a decent volume for the CD. Anyone else notice this...?

I used 0.33mF tantalum capacitors to get rid of the DC bias, that's what was recommended...

03-04-2001 14:18:41

New MessageRE:Low levels on line-out? (modified 0 times) starfish
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Yamaha Sound Chip, Line Level Output, Version 1 ~ V4 (Not for V5) ButtonPuncher's Notes:
I have use this a Few Times. Follow Link For GREAT M$WORD Document with Color Photo !
Did You Use Electrolytic Caps ???

I-Opener Areas / I-Opener Technical Stuff

RE:HEY Roastbeef!! Help me out! Great audio out... ButtonPuncher

Well, I'm back from testing and...

I tried a 100uF capacitor and I found that it blocks the DC bias and has an excellent frequency response from
20Hz to 20kHz. On the bad side, I found out that the Yamaha chip has to have a buffer placed on the output.
If you connect the Yamaha to your stereo through a capacitor directly, THE AUDIO WILL BE VERY BAD. This is
because your stereo will place too large of a load on the Yamaha chip.

To fix this you need to wire up an Op-amp from radio shack. The part only costs a two bucks and is VERY
easy to wire up.

For all of the details on my testing and for the wiring diagram please download the Word document from the
link below:

http://www.execpc.com/~theshoes/bentemp/i-opener%20audio.zip

This should give you CD quality audio out of the i-Opener. Oh yeah, the zip file is about 200k and all of the
readings were taken with my Fluke 89 IV multimeter. (the peak to peak readings were calculated)

Once I borrow a scope from work for the weekend, I will post any new findings and results.

Also, please tell me if the word document works out for you.

If you need to contact me directly, my e-mail address is buttonpuncher@yahoo.com

05-31-2000 10:20:44 P.M.

03-04-2001 22:56:37

New MessageRE:Low levels on line-out? (modified 0 times) oproot
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Booker:

You used .33mF capacitors, the site recommends .33uF or .47uF (uF not mF)

.33mF = 330uF

I would recommend getting either some electrolitic (non polar), ceramic disc, or tantalum capacitors between .47uF and 1.0uF. (Preferably get the .47's, but if you can't kind find them (radio shack doesn't carry them, i had to get mine at a specialty electonics store), then anything under 1uF should work)

Make *SURE* they are in uF, and if they are not, here is a conversion table in case to figure out if they will work:

1uF = .001mF
1uF = 1,000nF
1uF = 1,000,000pF

*oproot*

03-04-2001 23:40:21

New MessageRE:Low levels on line-out? (modified 0 times) Booker
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Doh... yeah, they were .33mF tantalum caps... doh.

So... let's see... if I went way to high (330uF), then it should be cutting out more of the low frequencies? Well, I'll give it a shot with the right values (grumble...) and see if that fixes it. :)

03-05-2001 22:54:35

New MessageRE:Low levels on line-out? (modified 0 times) Booker
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Oh, and regarding the values... the spec sheet says .33uF to 1.0uF is ok...

Also, it says that the line out / docking pins "can drive loads greater than 1 kOhm rail to rail." Anybody know what the input impedance of a preamp is...?

03-05-2001 22:57:38

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