http://www.chipamp.com/lm4780.shtml
Could someone please confirm that this kit is using 2x stereo chips in mono mode. (It says x2 in the kit list). And hence is capable of 2x 120W (8ohm).
This looks perfect to drive my dual voice coil driver ???
Jim
Could someone please confirm that this kit is using 2x stereo chips in mono mode. (It says x2 in the kit list). And hence is capable of 2x 120W (8ohm).
This looks perfect to drive my dual voice coil driver ???
Jim
I will put the transformers(s) and amps in 1 box and wire a single rca socket to both amp inputs.
??What VA rating of transformer would you recommend ?
ie for 2x120W should I use 240VA or something bigger?
My AV amp handles gain and phase. So I probably don't need gain control (although I might add a passive attenuator just for the hell of it - as I've not built one before)
But I would like an adjustable rumble filter to protect the excursion on ported subs.
??How do I build in an adjustable rumble filter?
I'm guessing this is such a simple thing that no-one has asked it before!
cheers
jim
??What VA rating of transformer would you recommend ?
ie for 2x120W should I use 240VA or something bigger?
My AV amp handles gain and phase. So I probably don't need gain control (although I might add a passive attenuator just for the hell of it - as I've not built one before)
But I would like an adjustable rumble filter to protect the excursion on ported subs.
??How do I build in an adjustable rumble filter?
I'm guessing this is such a simple thing that no-one has asked it before!
cheers
jim
is it a newer tempest? cause the originals were dual 8's but i think the ones they are shipping out now are either dual 8 or dual 4
also make sure you are feeding the same signal to both amps.
a rumble filter i just a variable high pass, look up active cross overs or digital filters and you will find tons of info.
what alignment are you using with the tempest?
also make sure you are feeding the same signal to both amps.
a rumble filter i just a variable high pass, look up active cross overs or digital filters and you will find tons of info.
what alignment are you using with the tempest?
You're right, the old Tempest is 2x8ohm.
The current alignment is EBS(?). It's in a 220l ported sonotube tuned to 17Hz.
Currently it is being driven by a 2x80W Pioneer stereo amp which has proven adequate so far. Although this alignment would be happy up to 300W.
My main concern is going beyond xmax if i crank it up and it gets fed some sub 15Hz signals.
Can I build a passive high pass filter ?
The current alignment is EBS(?). It's in a 220l ported sonotube tuned to 17Hz.
Currently it is being driven by a 2x80W Pioneer stereo amp which has proven adequate so far. Although this alignment would be happy up to 300W.
My main concern is going beyond xmax if i crank it up and it gets fed some sub 15Hz signals.
Can I build a passive high pass filter ?
Its not practical to make one you need alot of mH so you would have to buy several like 10mH coils and series. Active is the way to go. sub sonic filter has a good one I would like to build sometime but havent got around to it.
You cannot get 120W into 8 ohms with a single chip in parallel mode. The most you can get in the 60W range.
For your application, I think the best thing would be bridge parallel into 4 ohms. With 25V rails, this delivers about 230W. The only simple options are 2x60W (two chips, 35V) into 8 ohms or 1x120W into 4 ohms (one chip, 25V).
As you can see, the decision you make is important because it will determine the transformer you buy.
For your application, I think the best thing would be bridge parallel into 4 ohms. With 25V rails, this delivers about 230W. The only simple options are 2x60W (two chips, 35V) into 8 ohms or 1x120W into 4 ohms (one chip, 25V).
As you can see, the decision you make is important because it will determine the transformer you buy.
Running VC in parallel he will be running a 4 ohm load, which to my knowledge will pull 120w out of one 4780 when the chip is configured in parallel mode.
Personally i have a tempest in a 9 cuft box roughly ported to 20hz running off a PE 250w plate amp, it was more then enough to bottom it out even though i never bottomed it out.
I think if you are happy running with 80w per coil right now, you might want to go for the bridged parallel mode, two chips going to one output, which will be very similar in output to the PE plate amp.
Also typical "rumble" filters are 18dB/oct and you could very easily build those filters using an dual op amp, BB has a few, if not on a solderless bread board you have plenty of room to mess around with it.
Personally i have a tempest in a 9 cuft box roughly ported to 20hz running off a PE 250w plate amp, it was more then enough to bottom it out even though i never bottomed it out.
I think if you are happy running with 80w per coil right now, you might want to go for the bridged parallel mode, two chips going to one output, which will be very similar in output to the PE plate amp.
Also typical "rumble" filters are 18dB/oct and you could very easily build those filters using an dual op amp, BB has a few, if not on a solderless bread board you have plenty of room to mess around with it.
WorkingAtHome said:
Not into 8 ohms. ((35-3)^2/2)/8=64
G4ME said:
No. You can get 120W into 4 ohms in parallel mode. You cannot run the chips in bridge mode into 4 ohm loads without paralleling, at least not for any useful powers.
Regardless, Brian's boards are setup for parallel operation, not bridge mode. You can however easily bridge parallel two ICs using DRV134. Digi01 and others have PCBs for this purpose.
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