| Fryguy |
this is going to be my first building of anything electronic, and I want to go straight to a bridged setup, so I can get the power I desire first try.
The towers I'm using will most likely be 8ohm (still being designed), so I'm guessing a pair of lm3875s bridged will do what I want? |
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| cdoggy81 |
If you trya pair of lm3875s bridged it will require a balanced driver (think DRV134). Parallel would be easier (just add output resistors).
If you can, I would wait for Brian's LM4780's. I think this would be the answer for you. |
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| mAJORD |
though fairly new and not widley tested by any1 , early reports from the guys on here suggest the 4780s are a good chip. and would be great for what you need... single chip 60x 2 that could give you 120 x 2 if u use 2 chips . configured in paralel.
I beleive someone is sharing a nice compact PCB design for such a chip.. (paralell).
-oops sorry i didnt see your post,,, yes that would probably be brians boards im thinking of |
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| Fryguy |
| I thought that parallel only yielded more stability at 4ohms, not more power at 8? |
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| MWP |
| quote: | Originally posted by Fryguy
I thought that parallel only yielded more stability at 4ohms, not more power at 8? |
You are correct. |
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| Fryguy |
| So then wouldn't mAJORD's suggestion not work for me? I'm looking for 100x2 @ 8ohms, and I don't care about 4ohm stability... |
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| mAJORD |
| My appologies , I meant Bridge mode |
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| theChris |
fryguy, i am attempting to finally finish my lm4780 board. if you don't solder much i wouldn't suggest it. it's not that hard, but it takes patientice and the ability to keep a clean tip...
the board allows for bridge operation, and is pretty featureful, but not as small as other boards. it's meant to be very versitile. in anycase, i may be selling a limited number of them soon. i plan to get prototypes made for a setup similar to your's tomorrow.
i'm not sure if brianGT is making a non-parallel board as well?
in anycase, if you want an easy time, i may be able to get you a copy of the final amp board that me and my friends will use in our amps -- a quad lm3886tf board with features.
here is my breakdown of chips:
lm3875tf -- the easiest chip to work with, giving great results
lm3886tf -- a great chip giving extra power and handling some tougher loads better then the 3875tf.
lm3886t -- an non-insulated version, allowing for better heat dissipation and hopefully more power.
lm4780 -- a big chip. i'd use it for parrallel amps, though it;ll work for bridged or stereo!
for you, i suggest 2x lm3886tf's. |
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| netgeek |
| quote: | Originally posted by theChris
for you, i suggest 2x lm3886tf's. |
I believe you could use Brian's existing LM3875 boards with the LM3886s with some very minor mods (I'll have to check, but I believe you just need to run -V to an additional pin on the 3886)...
Bill |
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| theChris |
the +in and -in are different pins. the lm3875 has no mute, the 3886 does. the 3875 doens't have a ground pin.
the 3876 and 3886 and 2886 are about interchangeable, but the 3875 isn't. the 3785 board might be fixable, but traces would likely have the be cut and wires added... IMO more trouble then it is worth. |
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