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#1031 | |
diyAudio Member
Join Date: Dec 2009
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Quote:
Just curious what sensitivity number would be considered low to medium? I'm building a pair of speakers with dayton Classic 8's. The sensitivity is around 88 db. I'm hoping a Audiosector classic LM3875 will match up OK. |
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#1032 |
R.I.P.
Join Date: Jul 2004
Location: Scottish Borders
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I'm using 88dB sensitivity 8ohm speaker on a 3886. It plays low level and medium level nicely.
It becomes "loud" if the SPL is raised too high. It clips transients.
__________________
regards Andrew T. |
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#1033 |
diyAudio Member
Join Date: Dec 2009
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Thanks Andrew!
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#1034 |
diyAudio Member
Join Date: Nov 2009
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Hi everybody,
I just finish my second chipamp with the lm3875 kit. This time, I made a separated PS and a passive preamp. When the amp is connected with the preamp there's no noise, but when the cd is connected to the preamp I can hear a little buzz. But, when my ipod only is connected with the preamp there's no noise. The preamp is made with an 20K pot and a grayhill switch for channel selection. To connect the amp with the preamp, I decided to try xlr 3 pins (not balanced) pins 2 and 3 for left and right signal and pin 1 for ground. The ground signal (xlr pin 1) at the amp is connected at ground star on a copper bar connecting the 2 boards. I don't know what is the problem. 1-Ground loop ? 2-My xlr setup ? 3-impedance matching ? I will be glad to have some suggestions. |
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#1035 | |
diyAudio Member
Join Date: Nov 2009
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Quote:
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#1036 |
diyAudio Member
Join Date: Jul 2005
Location: Hoensbroek
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Attached you can see the progress of my gainclone with the LM4780 kits from Peter Daniel. The LM4780's will be bridged and are mounted on their heatsinks (left & right) with stips. Power supply star ground is on the heat sink.
The enclosure will be complete aluminium. The rest of the enclosure is being painted. But i did not find a solution yet for a nice front panel. http://www.diyaudio.com/forums/attac...1&d=1268338696 http://www.diyaudio.com/forums/attac...1&d=1268338696 An identical second amp will be built. After that i will use them in an active setup. |
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#1037 |
diyAudio Member
Join Date: Nov 2009
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Hi,
I want to know if the value(22k) for r1 and r2 in the lm4780 is critical. I want to use resistors I actually have in my bin and the nearest value I have now is 21.5K with 1% tolerance. Will it be ok to use 21.5K ? |
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#1038 |
diyAudio Member
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The resistor values you have on hand are perfectly fine.
__________________
www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC |
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#1039 |
diyAudio Member
Join Date: Dec 2003
Location: New England
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Has anyone ever measured the peak to peak current of the LM3875 / LM3886 / and LM4780 gainclones?
Thanks |
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#1040 |
R.I.P.
Join Date: Jul 2004
Location: Scottish Borders
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I have not, the specification guarantees 7Apk when Tc=25degC.
__________________
regards Andrew T. |
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Thread | Thread Starter | Forum | Replies | Last Post |
Commercial complete Gainclone kit for a beginner? | gychang | Chip Amps | 371 | 20th January 2015 08:07 AM |
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