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Chip Amps Amplifiers based on integrated circuits

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Old 13th May 2004, 08:24 PM   #311
carlosfm is offline carlosfm  Portugal
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Quote:
Originally posted by air
Carlos: What differences have you made in the design between the headphonamp and the preamp? (except the different ops) Other gain? Output impedance?
1. Other op-amp (the beautiful OPA2132).
2. More gain (I don't remember, but I think that I set the gain at around 10x).
3. 100 ohm output resistor
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Old 26th May 2004, 02:19 PM   #312
KT is offline KT  United States
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If anyone makes a finalized version of the board, any interest in selling one or two? I think there are a bunch of us who would like to give it a try.

Regards,
KT
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Old 26th May 2004, 02:29 PM   #313
TeePee is offline TeePee  United Kingdom
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I'll take 5
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Old 26th May 2004, 08:04 PM   #314
jonclancy is offline jonclancy  United Kingdom
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....perhaps with provision for paralleled output buffers???

Jon
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Old 26th May 2004, 09:02 PM   #315
Alcaid is offline Alcaid  Norway
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I've made a PCB layout (continuesly modifying it, though), but I haven't buildt it yet (exams ). Currently discussing it here.

Current status:
Attached Images
File Type: jpg preamp.jpg (91.0 KB, 1198 views)
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Old 26th May 2004, 09:43 PM   #316
skilpad is offline skilpad  South Africa
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Hi Alcaid,

Some comments on your BUF pre,

This is probably splitting hairs but ideally the current charging
the main reservoir caps C11,12 should not be conveyed by tracks passing right underneath the opamp
If however you plan to do a copper pour on say the top layer connected to GND then you might get
away with routing only +15, -15 on the bottom layer below the opamp
This sed I still believe that you could gain from supplying power from the BUF's side of the board and
moving C11,12 to either side of the BUF so as not to increase the distance between the opamp and the BUF

I hope this helped

Regards
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Old 26th May 2004, 09:56 PM   #317
Alcaid is offline Alcaid  Norway
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Quote:
Originally posted by skilpad
Hi Alcaid,

Some comments on your BUF pre,

This is probably splitting hairs but ideally the current charging
the main reservoir caps C11,12 should not be conveyed by tracks passing right underneath the opamp
If however you plan to do a copper pour on say the top layer connected to GND then you might get
away with routing only +15, -15 on the bottom layer below the opamp
This sed I still believe that you could gain from supplying power from the BUF's side of the board and
moving C11,12 to either side of the BUF so as not to increase the distance between the opamp and the BUF

I hope this helped

Regards
Don't know if I understood you correctly, or you understood me. The red layer is the top layer, and it is a groundplane. The blue is the bottom layer, and it only contains V+, V- and signal routing.
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Old 26th May 2004, 10:15 PM   #318
skilpad is offline skilpad  South Africa
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Hi Alcaid,
I was revering to the smaller version of the board without the pot
but I see that the final version is done quite differently and I can't spot any problems there.

Best of luck

Skilpad
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Old 8th June 2004, 05:49 PM   #319
jhead is offline jhead  United States
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Default PCB's

When you should get around to finializing your design and have boards made I would be interested in possible two or more I'm sure others will also have like interest in what your doing
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Old 8th June 2004, 06:56 PM   #320
air is offline air  Finland
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carlosfm:

Thank you,

I built one of these (opa627 + buf634, gain ~10)

I have tested the preamp, and it sounds great. But, it sounds even better without the buf634 Maybe this is because I dont need the buf, when my preamp is close to my poweramp, or some other cause. Also tried it with headphones, and it sounded great too.. havent tried headphones with only opa627 yet, but someday I will..
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