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Old 9th October 2004, 07:55 PM   #1
m127 is offline m127  Hungary
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Default Gainclone for an active subwoofer

Hi All,
I have built a Gainclone with LM1875s, and I am very pleased with its performance. Its sound is excellent and its power is far enough for me and my room.
The next step I want to take is try to get those 2 octaves which are too low for my speakers. I am planning to build an active sub. What I want is fast, clean bass, not big power. I like the gainclone idea very much, and I know (I've seen it on my oscilloscope) that my Gainclone is able to produce nice low frequency sounds. This gave the idea of building an active subwoofer with a (mono) gainclone. I tried to search through the forum for this, but didn't manage to find anything. Has anyone tried this? Should the LM1875 be able to handle this or should I try to get an LM3875 instead (they are not easy to get here)? Are there any possible problems just because it will drive a subwoofer? What special things should I take care of? Does anyone have some schemas showing how to connect the input signal of that amp? Is there any simple solution for the low-pass filter?
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m127
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Old 9th October 2004, 09:18 PM   #2
Nuuk is offline Nuuk  United Kingdom
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I am powering my TL woofers with LM3875's but with the addition of 10,000 uF per rail. I am surprised at how well this works (-3 db at 22 Hz) although I will also try a bridged GC to see if that is any better.
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Old 28th October 2004, 08:30 AM   #3
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Im interested to know if anyone else runs the LM3*** chips to power a sub?

I currently have a stereo LM3875 igc but no where near enough bass. So i need and active sub. Plus i have loads of these chip's
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Old 28th October 2004, 03:41 PM   #4
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I have 2 lm3886's that power each coil of an Adire Shiva. It's more power then it can use in the box it's in.

There are a few pictures of it on my site.
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Old 28th October 2004, 04:06 PM   #5
flubug is offline flubug  United States
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Thumbs up LM3886 subwoofer amp

I am using a ParaPix subwoofer amp I picked up on eBay to power a Dayton 10'"DVC woofer in a sealed cabinet. This amp uses two LM3886 ICs which can supposedly be bridged though I haven't tried that. I got it sans xformer and hooked it up with a 24-0-24 initially followed by a 20-0-20 as the final choice. This amp was sold by Apex Jr. some time back and his site (http://www.apexjr.com/parapixinfo.html) has very thorough documentation including schematics.

I like it so much I'm now building my own using LM3886's.
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Old 28th October 2004, 08:30 PM   #6
joensd is offline joensd  Germany
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Quote:
What I want is fast, clean bass, not big power.
Then you MIGHT be satisfied with just one chip.
If you havenīt got it already you should buy a LM3886 preferably due to bigger output current in comparison to LM3875.
You can of course also parallel 2-3 LM1875 to get about the same power.
Will it be an 4Ohm sub? 20W is the limit with one chip.
With an 8Ohm sub you get about 30W max.

Quote:
I am powering my TL woofers with LM3875's but with the addition of 10,000 uF per rail. I am surprised at how well this works (-3 db at 22 Hz) although I will also try a bridged GC to see if that is any better.
Any info on the woofers? Havenīt found them on your webpage.
Guess they are 8Ohm if you thinking about bridging?

Cheers
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Old 28th October 2004, 09:22 PM   #7
mateo88 is offline mateo88  United States
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Use the lm3886. In my opinion the bass sounds much better than with an lm3875. It's much tighter and punchier.
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Old 29th October 2004, 02:15 AM   #8
Aunkst is offline Aunkst  United States
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I have a single lm3886 running my sub. it has more power than I can realistically use. because seriously. 40-50 watts of REAL power is pleanty for all but really big rooms.

sounds great. I use a tl084 for a simple line level crossover. again sounds great. simple to work with.
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Old 19th November 2004, 12:05 PM   #9
aeon is offline aeon  Poland
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Default tl084 for a simple line level crossover

Hi, could you provide me some more info about that line level xover? Some schematics, PCB diagram etc?

I'm not very good in electronics, but I can follow instructions, can read diagrams, I know what parts doing, can solder and do PCB

Thanks

AeoN
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Old 19th November 2004, 01:15 PM   #10
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Quote:
Originally posted by Scribble
Im interested to know if anyone else runs the LM3*** chips to power a sub?

I currently have a stereo LM3875 igc but no where near enough bass. So i need and active sub. Plus i have loads of these chip's
Here is the example I have using BrainGT's LM3875 kits
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