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Chip Amps Amplifiers based on integrated circuits

Joe Rasmussen "Trans-Amp" - 40 Watt Transconductance "Current Amplifier"
Joe Rasmussen "Trans-Amp" - 40 Watt Transconductance "Current Amplifier"
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Old 7th March 2015, 03:02 PM   #121
superpete is offline superpete  Canada
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Hi Joe, can I use a lm3886 in the same circuit? I have 10 of them I never got to use...
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Old 7th March 2015, 04:31 PM   #122
yu3ma is offline yu3ma  Serbia
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Here is one similar approach published in 2012, not exactly transconductance amplifier but similar in a way of wiring in order to reduce DC offset as some components in input/FB stage are removed in order to get better performance.
Wiring is very very import and need to keep it as shown on schematic.
Same rules apply and for Joe's version.

More info about this design here (use Google translate):
HQ modifikacija za TDA7294 – HiFi Audio Amplifier 5Hz – 200Khz YU3MA
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Old 7th March 2015, 07:41 PM   #123
AndrewT is offline AndrewT  Scotland
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Yu,
all the Signal wiring should not be taken to that star type Power Ground.

All the Signal wiring should remain close coupled Flow and return Pairs with low Loop Area.
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Old 31st March 2015, 07:46 AM   #124
kp93300 is offline kp93300  Malaysia
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Default this amp compatible with markaudio 12 P

I have ordered the Lm 3875 chip .
I attached the spec for my speaker.
Is this speaker compatible ?
Do I need a dc detection relay in the out put ?
What is the range of input Voltage power that will work without changing other part value ?
thanks

kp93300
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Old 31st March 2015, 08:26 AM   #125
syklab is offline syklab  United States
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My friend had the PCB made for us to experience this current amp, I am using the Power supply board from PD's chipamp with a 300VA 26VAC x 2 R-core transformer and it is working nicely. I have been using it to drive a pair of the CHN70 for 2 weeks already and it sounded much better than my class D amp. No speaker protection yet, I don't think it is needed, no power on/off pop.
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Old 31st March 2015, 11:16 AM   #126
kp93300 is offline kp93300  Malaysia
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Hi syklab,
Can you post a picture of the amp ?
Can you elaborate on the sound signature of the amp ?
what size heat sink ?
Any dc offset?
I have send you a PM
thanks
kp93300
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Old 31st March 2015, 02:50 PM   #127
syklab is offline syklab  United States
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Click the image to open in full size.

Click the image to open in full size.

The DC is measured about 0.016V

Last edited by syklab; 31st March 2015 at 02:53 PM.
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Old 31st March 2015, 09:24 PM   #128
thiagomogi is offline thiagomogi  Brazil
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Article based on Elliott

Variable Amplifier Impedance

not tested
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Old 1st April 2015, 07:44 AM   #129
padamiecki is offline padamiecki  Poland
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how does it sound comparing to pure current drive?
is there big difference?
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Old 1st April 2015, 01:12 PM   #130
Joe Rasmussen is offline Joe Rasmussen  Australia
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Quote:
Originally Posted by AndrewT View Post
Yu,
all the Signal wiring should not be taken to that star type Power Ground.
Absolutely. I noticed that straight away.

.
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