I reworked my bridged LM4780 amplifier, changing the 4.7uF polypropylene caps to 47uF NP electrolytics, put in some load balancing resistors, kept the soft-start circuitry:
the PCB is a tad smaller -- gonna burn me some boards this evening.
jack
An externally hosted image should be here but it was not working when we last tested it.
the PCB is a tad smaller -- gonna burn me some boards this evening.
jack
the schematic is on page 6 of the National PDF for the '4780 -- i have found that the folks at National have done a pretty good job in the various configurations of the 4780, 3886, 3875.
this image might be a little clearer, but is large:
this image might be a little clearer, but is large:
An externally hosted image should be here but it was not working when we last tested it.
Member
Joined 2004
Re: LM4780
National doesn't pay attention to star-grounding in their layout, the space for the caps is smaller than the polypropylene ones used in real life and they also use a socket for the LM4780.
i cleaned up the layout, but the old GIF was over-written with the new one, sorry.
RCBandwidth said:
National doesn't pay attention to star-grounding in their layout, the space for the caps is smaller than the polypropylene ones used in real life and they also use a socket for the LM4780.
i cleaned up the layout, but the old GIF was over-written with the new one, sorry.
well, the boards just came back from the proto-shop -- here's the first one I've assembled:
the fit of parts is a bit snugger than I would like -- so when I have boards made it will be a bit more relaxed. the boards measure about 3.00 X 2.75"
An externally hosted image should be here but it was not working when we last tested it.
the fit of parts is a bit snugger than I would like -- so when I have boards made it will be a bit more relaxed. the boards measure about 3.00 X 2.75"
Hey Fellow Jerseyite.....
Just curious, but will you be offering these boards to the masses?
And what type of supply configuration will you be using?
I'm a curious newbie to this site, drooling over all of the different chipamp possibilities. Currently handwiring the 3875tf, but my heart is thumpin' o do the 4780
reever
Just curious, but will you be offering these boards to the masses?
And what type of supply configuration will you be using?
I'm a curious newbie to this site, drooling over all of the different chipamp possibilities. Currently handwiring the 3875tf, but my heart is thumpin' o do the 4780
reever
yeah, the people's republic of New Jersey --
I usually make up some boards for my own use and to figure out what needs fixin' -- then have a few hundred or so made with silk screen and soldermask and sell them at a little over cost -- the immediate imperfections I noted are that the trace for the mute function is too close to the mounting hole, there is a need to separate the caps by a few 0.010" so they seat themselves squarely, and the zobel and decoupling resistors could be spaced a bit more comfortably.
i am using my "generic" power supply board -- an easy single sided board -- with a quad of MUR860's and 10,000 uF filtration. i've had quite a few requests for a regulated version of this supply, so this might be in the works, along with a "quiet" switching supply for auto use. stay tuned, nothing goes onto my website until it's been thoroughly tested.
I usually make up some boards for my own use and to figure out what needs fixin' -- then have a few hundred or so made with silk screen and soldermask and sell them at a little over cost -- the immediate imperfections I noted are that the trace for the mute function is too close to the mounting hole, there is a need to separate the caps by a few 0.010" so they seat themselves squarely, and the zobel and decoupling resistors could be spaced a bit more comfortably.
i am using my "generic" power supply board -- an easy single sided board -- with a quad of MUR860's and 10,000 uF filtration. i've had quite a few requests for a regulated version of this supply, so this might be in the works, along with a "quiet" switching supply for auto use. stay tuned, nothing goes onto my website until it's been thoroughly tested.
Paraclone and Bridgeclone compared
this chart compares the THD+N% for the bridged amp and the parallel amp -- this chart will be updated as I finish the testing. The dotted lines represent the results for the parallel amplifier.
this chart compares the THD+N% for the bridged amp and the parallel amp -- this chart will be updated as I finish the testing. The dotted lines represent the results for the parallel amplifier.
An externally hosted image should be here but it was not working when we last tested it.
MORE
Here's more results, placing the amplifier in a steel cabinet:
Here's more results, placing the amplifier in a steel cabinet:
An externally hosted image should be here but it was not working when we last tested it.
Here's the amp with 8 and 4 ohm loads, 1,10,50 and 100W (and the bridged version at 120W)
An externally hosted image should be here but it was not working when we last tested it.
The boards are back -- sorry for the poor depth-of-field, but you get the idea -- all silk screened and solder-masked.
An externally hosted image should be here but it was not working when we last tested it.
4780
This is for jackinnj, Lsharptec1 and other conjurates of the
new republic of New Jersey. I´m in the norwest of this beautiful
and most envied state....
I have just one question related to the 4780 chip amplifier, is
it worth the work on this device?
I´ve been building discrete amps for so long that I forgot that
I have a few chips of these and respective boards professionally made to go along. Another words I have everything to build
the parallel version but I haven´t done anything because I
really don´t know about its quality.
Could you guys please tell me if I should heat up my iron for
this project?
This is for jackinnj, Lsharptec1 and other conjurates of the
new republic of New Jersey. I´m in the norwest of this beautiful
and most envied state....
I have just one question related to the 4780 chip amplifier, is
it worth the work on this device?
I´ve been building discrete amps for so long that I forgot that
I have a few chips of these and respective boards professionally made to go along. Another words I have everything to build
the parallel version but I haven´t done anything because I
really don´t know about its quality.
Could you guys please tell me if I should heat up my iron for
this project?
jmateus,
I am in the process of putting together an amplifier that will use both the parallel configuration and the bridged configuration.
It is not complete yet, but I have built other chip amps and am very satisfied with the sound quality.
The great part about this hobby is the thrill of doing it yourself.
If you are a noob to the hobby, I suggest that you stick with a kit or a finalized design.
If you are an experienced engineer or technician, you can experiment with the circuitry, changing component values to yield desired gains or bandwidth limits.
The simple answer to your question is YES ... it is worth it.
Larry
I am in the process of putting together an amplifier that will use both the parallel configuration and the bridged configuration.
It is not complete yet, but I have built other chip amps and am very satisfied with the sound quality.
The great part about this hobby is the thrill of doing it yourself.
If you are a noob to the hobby, I suggest that you stick with a kit or a finalized design.
If you are an experienced engineer or technician, you can experiment with the circuitry, changing component values to yield desired gains or bandwidth limits.
The simple answer to your question is YES ... it is worth it.
Larry
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