I have just finished my first LM3886 dual Mono Amp. It is based on the BrianGT PCB. For the PSU I use a 160 VA toroid transformer (2x22VAC) with the Carlosfm inspired snubberized design. Since I use a 9-pin Sub-D for the interconnection I have the option to power each channel with a separate PSU. There are also two 1800uF caps for each channel near the chips power pins.
(I am not so happy with the Sub-D connector. The contacts are rated with a maximum of 3A/pin. Maybe I will use the high-current-version for my next design.)
The enclosure is simply built with two heat-sinks (Fischer SK85 -160x40x50(mm)) and 4 aluminium plates The overall dimension are 50x180x160 (mm) (H-W-D) without the knob, connectors and spikes. I think that the heat-sinks are a bit oversized for this design. For the connectors (Speaker and RCAs) I,ve used types that I’ve found in the nearest store. Cardas or WBTs are not really an option for my budget.
The last think I have finished was the knob for the volume control. It is built in massive brass wit 40 mm in dia. Now I go and search for a nice enclosure for the PSU that match to the Amp-design and will – with respect -not be a copy of the great 47 Lab design.
For me the best sound impression for this Amp-design is without any cap in the signal path and the additional caps near the LM3886 power pins. Since the output offset voltage for both channels are below 30 mV I’ve removed the offset compensation cap too.
Finally:
Without the inspirations and experiences from all the great people in this forum I’d never started this Chip Amp project.
I hope I don’t boring you if I add some pictures of my finished Amp.
Thank you all.
Bernd
(I am not so happy with the Sub-D connector. The contacts are rated with a maximum of 3A/pin. Maybe I will use the high-current-version for my next design.)
The enclosure is simply built with two heat-sinks (Fischer SK85 -160x40x50(mm)) and 4 aluminium plates The overall dimension are 50x180x160 (mm) (H-W-D) without the knob, connectors and spikes. I think that the heat-sinks are a bit oversized for this design. For the connectors (Speaker and RCAs) I,ve used types that I’ve found in the nearest store. Cardas or WBTs are not really an option for my budget.
The last think I have finished was the knob for the volume control. It is built in massive brass wit 40 mm in dia. Now I go and search for a nice enclosure for the PSU that match to the Amp-design and will – with respect -not be a copy of the great 47 Lab design.
For me the best sound impression for this Amp-design is without any cap in the signal path and the additional caps near the LM3886 power pins. Since the output offset voltage for both channels are below 30 mV I’ve removed the offset compensation cap too.
Finally:
Without the inspirations and experiences from all the great people in this forum I’d never started this Chip Amp project.
I hope I don’t boring you if I add some pictures of my finished Amp.
Thank you all.
Bernd
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how did you engrave the wordings on the back?
Hi homer09,
I worked with the Front Panel Designer witch you can get for free from http://www.frontpanelexpress.com. With this smart tool it is easy to add some engraves to the panels.
Regards,
Bernd
Hi homer09,
I worked with the Front Panel Designer witch you can get for free from http://www.frontpanelexpress.com. With this smart tool it is easy to add some engraves to the panels.
Regards,
Bernd
well atleast ur chips will stay nice and cool. In computer overclocking ur heatsink is never to big!
thats really nice
thats really nice
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Joined 2004
DIY amplifier cabinet (wood)
This project started out as a way to use up some scrap veneer I had in the shop..most of the case is veneered MDF(cherry),the posts are solid cherry,the overlays under the knobs are walnut..I'm finishing up the amps(LM4780)..I am also in the process of building a matching case for a pre-amp. Bob C.
This project started out as a way to use up some scrap veneer I had in the shop..most of the case is veneered MDF(cherry),the posts are solid cherry,the overlays under the knobs are walnut..I'm finishing up the amps(LM4780)..I am also in the process of building a matching case for a pre-amp. Bob C.
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Joined 2004
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